Encyclopedia of Invasive Species 2 volumes : From Africanized Honey Bees to Zebra Mussels

n Encyclopedia of Invasive Species

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n Encyclopedia

of Invasive Species From Africanized Honey Bees to Zebra Mussels Volume 1: Animals

Susan L. Woodward and Joyce A. Quinn

Copyright 2011 by ABC-CLIO, LLC All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, except for the inclusion of brief quotations in a review, without prior permission in writing from the publisher. Library of Congress Cataloging-in-Publication Data Woodward, Susan L., 1944 Jan. 20– Encyclopedia of invasive species : from africanized honey bees to zebra mussels / Susan L. Woodward and Joyce A. Quinn. p. cm. Includes bibliographical references and index. ISBN 978–0–313–38220–8 (cloth : alk. paper) — ISBN 978–0–313–38221–5 (ebook) 1. Introduced organisms—Encyclopedias. I. Quinn, Joyce Ann. II. Title. QH353.W66 2011 2011026543 578.60 2—dc23 ISBN: 978–0–313–38220–8 EISBN: 978–0–313–38221–5 15 14 13 12 11

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This book is also available on the World Wide Web as an eBook. Visit www.abc-clio.com for details. Greenwood An Imprint of ABC-CLIO, LLC ABC-CLIO, LLC 130 Cremona Drive, P.O. Box 1911 Santa Barbara, California 93116-1911 This book is printed on acid-free paper Manufactured in the United States of America

n Contents General Introduction: Invasive Species—Concepts and Issues n xiii VOLUME 1: INVASIVE MICROORGANISMS, FUNGI, AND ANIMALS Preface n xxxv Alphabetical List of Invasive Microorganisms, Fungi, and Animal Entries n xxxix Microorganisms Avian Malaria (Plasmodium relictum capistranoae) n 1 Lyme Disease Bacterium (Borrelia burgdorferi) n 3 West Nile Virus (West Nile Virus) n 7 Fungi Bat White-Nose Syndrome Fungus (Geomyces destructans) n 11 Chestnut Blight Fungus (Cryphonectria parasitica) n 14 Chytrid Frog Fungus (Batrachochytrium dendrobatidis) n 18 Dutch Elm Disease Fungi (Ophiostoma novo-ulmi and O. ulmi) n 21 Sudden Oak Death (Phytophthora ramorum) n 25 White Pine Blister Rust (Cronartium ribicola) n 29 Invertebrates Bryozoan Lacy Crust Bryozoan (Membranipora membranacea) n 36 Tunicates Chain Tunicate (Botrylloides violaceus) n 39 Colonial Tunicate (Didemnum vexillum) n 42 Cnidarian Australian Spotted Jellyfish (Phyllorhiza punctata) n 45

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Annelid worms European Earthworms (Lumbricus terrestris, L. rubellus, Aporrectodea caliginosa, Dendrobaena octaedra, and others) n 48 Mollusks Asian Clam (Corbicula fluminea) n 53 Asian Green Mussel (Perna viridis) n 56 Chinese Mystery Snail (Cipangopaludina chinensis malleata) n 58 Common Periwinkle (Littorina littorea) n 61 Giant African Snail (Achatina fulica) n 64 Golden Apple Snail (Pomacea canaliculata) n 67 Naval Shipworm (Teredo navalis) n 70 New Zealand Mud Snail (Potamopyrgus antipodarum) n 73 Quagga Mussel (Dreissena rostriformis bugensis) n 76 Veined Rapa Whelk (Rapana venosa) n 79 Zebra Mussel (Dreissena polymorpha) n 82 Crustaceans Chinese Mitten Crab (Eriocheir sinensis) n 86 Green Crab (Carcinus maenas) n 90 Rusty Crayfish (Orconectes rusticus) n 93 Spiny Water Flea (Bythotrephes longimanus) n 95 Arachnids Honeybee Tracheal Mite (Acarapis woodi) n 99 Varroa Mite (Varroa destructor) n 102 Insects Africanized Honey Bee (Apis mellifera scutellata) n 106 Argentine Ant (Linepithema humile) n 110 Asian Longhorned Beetle (Anoplophora glabripennis) n 113 Asian Tiger Mosquito (Aedes albopictus) n 116 Brown Marmorated Stink Bug (Halyomorpha halys) n 120 Common Bed Bug (Cimex lectularius) n 123 Emerald Ash Borer (Agrilus planipennis) n 127

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Formosan Subterranean Termite (Coptotermes formosanus) n 131 Glassy-Winged Sharpshooter (Homalodisca vitripennis) n 134 Gypsy Moth (Lymantria dispar) n 138 Hemlock Woolly Adelgid (Adelges tsugae) n 142 Japanese Beetle (Popillia japonica) n 146 Multicolored Asian Lady Beetle (Harmonia axyridis) n 148 Red Imported Fire Ant (Solenopsis invicta) n 152 Vertebrates Fish Alewife (Alosa pseudoharengus) n 157 Asian Swamp Eel (Monopterus albus) n 160 Bighead Carp (Hypophthalmichthys nobilis) n 163 Brown Trout (Salmo trutta) n 166 Gizzard Shad (Dorosoma cepedianum) n 168 Grass Carp (Ctenopharyngodon idella) n 172 Lionfish (Pterois volitans / P. miles) n 175 Mosquitofish (Gambusia affinis and G. holbrooki) n 178 Northern Snakehead (Channa argus) n 182 Rainbow Trout (Oncorhynchus mykiss) n 185 Round Goby (Neogobius melanostomus) n 187 Sea Lamprey (Petromyzon marinus) n 190 Silver Carp (Hypophthalmichthys molitrix) n 194 Spotted Tilapia (Tilapia mariae) n 196 Walking Catfish (Clarias batrachus) n 198 Amphibians African Clawed Frog (Xenopus laevis) n 201 American Bullfrog (Lithobates catesbeianus) n 205 Coqui (Eleutherodactylus coqui) n 208 Cuban Treefrog (Osteopilus septentrionalis) n 211 Reptiles Brown Anole (Norops [=Anolis] sagrei) n 214 Burmese Python (Python molurus bivittatus) n 217 Green Iguana (Iguana iguana) n 221

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Nile Monitor (Varanus niloticus) n 225 Birds Cattle Egret (Bubulcus ibis) n 228 Common Myna (Acridotheres tristis) n 232 Eurasian Collared-Dove (Streptopelia decaocto) n 234 European Starling (Sturnus vulgaris) n 237 House Finch (Carpodacus mexicanus) n 240 House Sparrow (Passer domesticus) n 243 Japanese White-Eye (Zosterops japonicus) n 246 Monk Parakeet (Myiopsitta monachus) n 248 Mute Swan (Cygnus olor) n 252 Rock Pigeon (Columba livia) n 256 Mammals Black Rat (Rattus rattus) n 259 Feral Burro (Equus asinus) n 262 Feral Cat (Felis silvestris catus) n 265 Feral Goat (Capra hircus) n 268 Feral Horse (Equus caballus) n 271 Feral Pig (Sus scrofa) n 275 House Mouse (Mus musculus) n 281 Indian Mongoose (Herpestes javanicus) n 284 Norway Rat (Rattus norvegicus) n 287 Nutria (Myocastor coypus) n 290 State-by-State Occurrences of Invasive Microorganisms, Fungi, and Animals n 295 Glossary n 311 Index n I-1 VOLUME 2: INVASIVE PLANT SPECIES Preface n xiii Invasive Plants in the United States: A Brief Overview n xvii Alphabetical List of Invasive Plant Entries n xxiii

CONTENTS n ix

Aquatic Plants Eurasian Watermilfoil (Myriophyllum spicatum) n 321 Giant Salvinia (Salvinia molesta) n 326 Hydrilla (Hydrilla verticillata) n 331 Water Chestnut (Trapa natans) n 335 Waterhyacinth (Eichhornia crassipes) n 339 Forbs Canada Thistle (Cirsium arvense) n 344 Chinese Lespedeza (Lespedeza cuneata) n 349 Common Mullein (Verbascum thapsus) n 353 Common St. Johnswort (Hypericum perforatum) n 358 Dyer’s Woad (Isatis tinctoria) n 362 Fig Buttercup (Ficaria verna) n 366 Garlic Mustard (Alliaria petiolata) n 369 Giant Hogweed (Heracleum mantegazzianum) n 372 Goutweed (Aegopodium podagraria) n 376 Halogeton (Halogeton glomeratus) n 379 Ice Plant and Crystalline Ice Plant (Carpobrotus edulis and Mesembryanthemum crystallinum) n 383 Japanese Knotweed (Fallopia japonica) n 387 Kahili Ginger (Hedychium gardnerianum) n 391 Leafy Spurge (Euphorbia esula) n 395 Musk Thistle (Carduus nutans) n 399 Perennial Pepperweed and Hoary Cress (Lepidium latifolium and Cardaria draba) n 404 Prickly Russian Thistle (Salsola tragus) n 409 Purple Loosestrife (Lythrum salicaria) n 414 Spotted Knapweed (Centaurea stoebe) n 417 Toadflax (Linaria dalmatica ssp. dalmatica and Linaria vulgaris) n 421 Yellow Starthistle (Centaurea solstitialis) n 427 Graminoids Asiatic Sand Sedge (Carex kobomugi) n 432 Buffelgrass (Pennisetum ciliare) n 435

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Cheatgrass (Bromus tectorum) n 439 Cogongrass (Imperata cylindrica) n 443 Common Reed (Phragmites australis ssp. australis) n 447 Cordgrasses and Their Hybrids (Spartina alterniflora, Spartina densiflora, Spartina patens, Spartina anglica, and Spartina alterniflora x foliosa n 452 Crimson Fountain Grass (Pennisetum setaceum) n 458 Giant Reed (Arundo donax) n 462 Japanese Stilt Grass (Microstegium vimineum) n 466 Johnsongrass (Sorghum halepense) n 469 Jubata Grass and Pampas Grass (Cortaderia jubata and Cortaderia selloana) n 472 Kikuyugrass (Pennisetum clandestinum) n 478 Medusahead (Taeniatherum caput-medusae) n 481 Quackgrass (Elymus repens) n 485 West Indian Marsh Grass (Hymenachne amplexicaulis) n 489 Shrubs Asiatic Colubrina (Colubrina asiatica) n 493 Brooms (Cytisus scoparius, Spartium junceum, Genista monspessulana, and Cytisus striatus) n 496 Exotic Bush Honeysuckles (Lonicera maackii, L. morrowii, L. tatarica, and L. x bella) n 502 Gorse (Ulex europaeus) n 508 Japanese Barberry (Berberis thunbergii) n 512 Koster’s Curse (Clidemia hirta) n 515 Lantana (Lantana camara) n 518 Multiflora Rose (Rosa multiflora) n 522 Rattlebox (Sesbania punicea) n 527 Tropical Soda Apple (Solanum viarum) n 530 Yellow Himalayan Raspberry (Rubus ellipticus) n 535 Trees Australian Pine (Casuarina equisetifolia) n 540 Brazilian Peppertree (Schinus terebinthifolius) n 544

CONTENTS n xi

Carrotwood (Cupaniopsis anacardioides) n 548 Chinaberry (Melia azedarach) n 551 Fire Tree (Morella faya) n 554 Melaleuca (Melaleuca quinquenervia) n 557 Paper Mulberry (Broussonetia papyrifera) n 562 Princess Tree (Paulownia tomentosa) n 565 Russian Olive (Elaeagnus angustifolia) n 568 Silk Tree (Albizia julibrissin) n 572 Strawberry Guava (Psidium cattleianum) n 576 Tamarisk (Tamarix chinensis T. ramosissima, T. parviflora, and T. gallica) n 579 Tree of Heaven (Ailanthus altissima) n 585 Velvet Tree (Miconia calvescens) n 589 Vines Chocolate Vine (Akebia quinata) n 594 Climbing Ferns (Lygodium japonicum and Lygodium microphyllum) n 597 English Ivy (Hedera helix) n 602 Field Bindweed (Convolvulus arvensis) n 606 Japanese Dodder (Cuscuta japonica) n 610 Japanese Honeysuckle (Lonicera japonica) n 614 Japanese Hops (Humulus japonicus) n 618 Kudzu (Pueraria montana) n 622 Mile-A-Minute (Persicaria perfoliata) n 626 Oriental Bittersweet (Celastrus orbiculatus) n 629 Porcelainberry (Ampelopsis glandulosa var. brevipedunculata) n 633 Swallow-Worts (Cynanchum rossicum and Cynanchum louiseae) n 636 Winter Creeper (Euonymus fortunei) n 640 Wisteria (Wisteria sinensis and Wisteria floribunda) n 644 Tables and Lists about Invasive Plants Common Names and Scientific Names n 649 State-by-State Designations of Invasive or Noxious Weeds n 665

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Pathways of Introduction for Plants n 673 Impacts of Invasive Plants n 678 Major Organizations and Publications Concerned about Invasive Plants n 687 Plant Species Listed as Invasive or Noxious by Organizations and State and Federal Governments n 689 Set Appendices Appendix A: American Species That Are Invasive Abroad n 695 Appendix B: Major Federal Legislation and Agreements Pertaining to Invasive Species n 699 Appendix C: Selected International Agreements and Conventions Pertaining to Invasive Species n 707 Appendix D: ISSG’s 100 of the World’s Worst Invasive Alien Species n 710 Glossary n 713 General Bibliography: Selected Classic and Contemporary Works and Major Internet Data Sources n 723 Index n 727

n General Introduction: Invasive

Species—Concepts and Issues

Just What Is an Invasive Species? Many different words are used to refer to those species that cause great concern among land managers, ecologists, and ordinary folk dealing with the consequences of organisms that have been transported from their places of origin and released to go wild in the waters, forests, grasslands, and deserts of the United States. Some are synonyms, others are not. Some terms may have subtle value-laden connotations, while others are attempts at scientific objectivity. “Plant people” use different words than “animal people.” There is as yet no consensus among scientists on what are the best terms to use, so the literature remains inconsistent and definitions sometimes vague. Several terms merely imply populations existing outside their native range and can be used more or less interchangeably: alien, exotic, nonnative, and nonindigenous. The term “alien” may be viewed as pejorative, causing unwarranted bias—and unnecessary actions—against all foreign species. Nonetheless, the official legal definition of “alien” was put forth by President Clinton’s Executive Order 13112 (February 3, 1999), which states that an alien species is, “with respect to a particular ecosystem, any species, including its seeds, eggs, spores, or other biological material capable of propagating that species, that is not native to that ecosystem.” This means that a species native to one part of the United States can be alien to another region of the country, as is the case with so-called native transplants or “domestic exotics” such as the American bullfrog (Lithobates catesbeianus) in western waterways, smooth cordgrass (Spartina alterniflora) in western salt marshes, or the House Finch (Carpodacus mexicanus) in eastern states. What constitutes a native species is open to question. Native species are generally considered “natural” and in their place of origin, i.e., the place where they belong. In the United States, native species are often those considered to have been here when Europeans first colonized the North American continent in the sixteenth century. This qualification, however, is based on two questionable concepts: (1) that North American environments were pristine before the arrival of Europeans in the fifteenth century, and (2) that only habitats not influenced by human activity are natural. Realizing that aboriginal peoples may have had profound impacts on North American ecosystems through their use of fire, their hunting, their trade, and their agriculture, some argue that the date dividing pristine from disturbed environments should be pushed back a few tens of thousands of years to when humans—the most invasive species of all—first set foot on the continent. Biogeographers tend to define native range as that geographic region where a species evolved to its contemporary form and to which it was long restricted by natural barriers. In the history of life, overcoming such barriers is a common occurrence, as is the removal of barriers. Species constantly disperse from their place of origin as their populations grow, as they evolve, as continents move and oceans shrink, as drainage systems pirate headwater streams from other river systems, and so forth. Long-distance migrant species populated distant oceanic islands and led to the exchange of plants and animals among continental

xiv n GENERAL INTRODUCTION

About Range Maps

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ange maps are usually constructed from records of species occurrence compiled in museum and herbaria collections. Each verified specimen is represented by a dot on a map, and usually the outermost dots are connected to form the range boundary. Adjustments are often made based on knowledge of the specific environmental conditions of the area and of the habitat requirements and ecological tolerances of the species in question. A given species thus does not occur everywhere in its mapped range, but only where conditions are suitable within the designated region. Information on the distribution of many species is often a matter of presence or absence in a particular area. Much of the information available for invasive plants, especially, comes as records of occurrence (or absence) in a political unit such as an entire state. Maps based on this information necessarily provide highly generalized distribution patterns. Larger political units, such as Texas or China, mean even more generalization. Absence of a species according to the maps may be because it is not yet recognized or recorded at a particular location. In order to present the best possible depiction of a species’ range the authors have consulted a variety of sources and synthesized often-conflicting information. Native ranges may be especially problematic because biological surveys are not advanced in many parts of the world and reliable range maps did not exist. In many cases the place of origin of a species that is invasive in the United States is simply not known or at best uncertain. Such instances are indicated by question marks on the maps. Plants, animals, fungi, and microorganisms have been carried around the world with humans for millennia, obscuring the history of their origins. Some have undergone subsequent evolution that complicates the picture further. Increasingly, genetic studies are confirming earlier scientific conclusions or shedding new light on the past travels of species and pinpointing their starting points with increased accuracy. Maps, like the species themselves, are dynamic. As new sightings and collections are made, the range maps may change. The reader wanting the most up-to-date information or more detailed information than can be derived from the small maps in this work is encouraged to seek out recent publications and local experts in the field. When comparing maps from different sources, the reader is cautioned that the appearance of distribution areas will vary when different map projections—methods of converting the spherical globe into a flat map—are used. Distortions in size, shape, or cardinal direction (N, S, E, W) are inevitable. The projections chosen for this volume (Eckert III for the world and Albers Equal-Area Conic for the United States) display fairly accurately true area or size relationships with minimal shape distortion. Areas closer to polar regions, as indicated by Greenland, are increasingly more distorted in shape and direction.

landmasses many times in the geological past. Species are still on the move, actively and passively, in the same manner as in the past. Those that arrive “on their own,” such as the Cattle Egret (Bubulcus ibis), are referred to as adventive species. The vast majority of species today, however, are transported, deliberately or accidentally, by humans. Such newcomers to a region are known as introduced species.

GENERAL INTRODUCTION n xv

Not all nonnative species are invasive; in fact, most are not. Legally, that term should be reserved for “an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health” (Executive Order 13112 of February 3, 1999). A legally defined term that predates “invasive” is nuisance species, which appeared in the Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990 (Public Law 101-636) and continues in use. An aquatic nuisance species was defined as a nonindigenous species that “threatens the diversity or abundance of native species or the ecological stability of infested waters, or commercial, agricultural or recreational activities dependent upon such waters.” It is the same thing as an invasive species. Some scientists dislike having the definition of invasive species dependent on negative impacts and prefer a more neutral definition that focuses on the population growth and range expansion of certain nonindigenous species. They would argue that impacts can be somewhat subjective and vague, and that range expansion or spread is the main process that distinguishes some nonnative species from others. For example, many a nonindigenous species arrives, reproduces, and establishes a population that is self-sustaining over several generations and perhaps for a very long time in natural and seminatural habitats at or near the point of entry; but it never spreads beyond the immediate areas of its introduction— i.e., it never become “invasive.” Such alien plants and animals may be categorized as established. Where they have become regular, functioning parts of a recipient ecosystem, even if far from the point of entry, they are considered naturalized. Some invasive plants are identified as “noxious” species, a category defined in the 1974 Federal Noxious Weed Act as “any living stage, such as seeds and reproductive parts, of any parasitic or other kind of plant, which is of foreign origin, is new to or not widely prevalent in the United States, and can directly or indirectly injure crops, other useful plants, livestock, or poultry or other interests of agriculture, including irrigation, or navigation, or the fish or wildlife resources of the United States or the public health.” Noxious plants are so designated by federal and state laws. For animals, the term injurious is used to describe those “species, including offspring and eggs, determined to be injurious to the health and welfare of humans, the interests of agriculture, horticulture or forestry, and the welfare and survival of wildlife resources of the U.S.” (Branch of Invasive Species, U.S. Fish and Wildlife Service). Under the Lacey Act (see Appendix B), the designation of such species is made by the U.S. Department of the Interior; and the importation and interstate transport of wild mammals, wild birds, fish, mollusks, crustaceans, amphibians, and reptiles so designated are regulated by the secretary of the interior. (Currently, no amphibians are on the list of injurious species, but in September 2009, the Defenders of Wildlife petitioned Secretary Salazar to place all amphibians on the list unless certified free of the chytrid frog fungus [Batrachochytrium dendrobatidis].)

The Size of the Problem According to many resource managers and ecologists, invasive species and potential invaders together constitute one of the major environmental threats facing the United States in the twenty-first century. Preventing or controlling the establishment of nonindigenous species is complicated by a number of uncertainties, including how many and which of the nonnative species will become abundant and widespread and inflict significant impacts on natural ecosystems; national, regional, and/or state economies; or public health. According to one estimate, some 50,000 species of plant, animal, fungi, and microbe have

xvi n GENERAL INTRODUCTION been transported to the United States. Of these, perhaps 6,500 have established viable, selfsustaining populations and 500 or so have become invasive in the sense both of demonstrating rapid population growth and range expansion and of causing harm or altering natural ecosystems. Actual numbers are difficult to obtain and are more reliable for some classes of organisms than others. Attention focused earlier and with greater federal funding on agricultural pests and nonnative aquatic species than on others, so more data are available for those groups. Inconsistent use of terms often further muddies the waters of how many species are invasive as opposed to simply introduced or naturalized. The figures that follow should only be considered indicators of the size of the problem and not definitive, accurate measures. Invasive Plants Plants in the United States consist of approximately 18,000 native species and 5,000 nonindigenous species. As is true for most if not all types of invasive species, the greatest numbers occur in Florida and Hawai’i. Florida is home to more than 900 naturalized plant species; Hawai’i reports 946. However, only some are invasive. Most plants that have become invasive were intentionally brought to the United States as ornamentals or for uses as varied as erosion control or herbal medicine. Others were accidental introductions, primarily as contaminants in crop seeds or hay or carried in ship ballast. Many nonnative plants alter natural ecosystems, displacing native species, many of which are rare or endangered, but impacts are far-reaching and varied. Nonnative plants are estimated to comprise 73 percent of the weeds of cultivated farmland and 45 percent of pasture weeds. Some plants may be easily contained in drier western climates where limited water prevents their spread, but may be unstoppable in the rainier eastern states. Others may be invasive in grasslands or deserts, but not in ecosystems where competition from other plants keeps them under control. Overall, 138 trees and shrubs are considered invasive in the United States. Some of the most notorious trees are salt cedar or tamarisk (Tamarix spp.), Australian melaleuca (Melaleuca quinquenervia), and Brazilian peppertree (Schinus terebinthifolius). Tamarisk depletes surface and groundwater supplies and makes soils so salty that other plants are unable to grow. Melaleuca infestations are not only threatening the Everglades’ unique ecosystem, but the tree is also detrimental to human health and causes increased incidence of fire. Brazilian peppertree is ranked with melaleuca as one of the worst invaders of the Everglades. In Hawai’i, unless checked, velvet tree (Miconia calvescens) could devastate native forests and alter hydrology as it has in Tahiti. Shrubs can be equally devastating. Tropical soda apple (Solanum viarum), from South America and now invasive in the southeastern United States, is a competitive plant in agricultural fields, both pasture and cropland. It also harbors insects or pathogens that severely damage and reduce yields of food crops. Gorse (Ulex europaeus), a large bushy shrub with many attractive yellow flowers, forms thorny thickets that impede passage and degrade the quality of recreational activities. The oily foliage and deep accumulation of dry matter cause fires to occur more frequently and to burn hotter. The common garden plant lantana (Lantana camara) is also a fire hazard in southeastern states, where it invades citrus groves. Its leaves and unripe fruit are toxic to animals and can cause death. More than 500 introduced forbs and graminoids are considered noxious weeds. Forbs may be as small as the 12 in. (30 cm) tall fig buttercup (Ficaria verna) or grow as large as giant hogweed (Heracleum mantegazzianum), which can be 25 ft. (7.6 m) tall with leaves

GENERAL INTRODUCTION n xvii

The Problem with Common Names and Why Scientific Names Are Surer Bets

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he common names of plants and animals are not always reliable indicators of what species is being discussed. Different names may be used by people in different parts of the country. For example, in the eastern United States the leafy weed known in most places as Japanese knotweed is called Japanese bamboo, although it is not even a relative of true bamboos, which are grasses. The misnomer points to another difficulty: common names frequently do not reflect the true identify of a plant or animal. Among the many tiny invasive animals causing problems in the Great Lakes is the spiny water flea, not an insect like real fleas but a crustacean. Scientific names may at first be strange tongue-twisters because they have been latinized, but they have been approved by international committees and linked to one species and one species only. Often the name provides insights into the nature of the organism or, the place where it was first discovered. Scientific names are revised from time to time as scientists come to new understandings about a species’ evolution and relation to other species, but while in current use they leave no doubt what plant, animal, fungus, or microorganism is being discussed. Each scientific name has two parts. The first word refers to the genus into which biologists have classified the species and the second identifies the particular member of the genus. Both words must be used to correctly designate a particular species. In the Encyclopedia’s species accounts, common names appear as the title of each entry, and entries are arranged within major categories alphabetically by common name. More frequently used alternate names, especially those of regional prominence, are given as appropriate. The scientific name—and some others that have been used in older literature (synonyms)—follow. A reader seeking more information should search according to the scientific name, or at least verify that the scientific name is the same, to be sure he or she is gathering data about the same organism as the one described in a particular entry.

as wide as 5 ft. (1.5 m). Fig buttercup displaces plants that are important sources of pollen and nectar for pollinating insects, threatening their existence. Contact with the sap of giant hogweed, a plant recently invasive in New England and the upper Midwest, causes a person’s skin to be susceptible to severe sunburns. Several thistles and thistle-like knapweeds degrade range and pasture land, and some, especially yellow star-thistle (Centaurea solstitialis), are very poisonous to livestock. Prickly Russian thistle (Salsola tragus), more commonly recognized as tumbleweed in the arid western states, looks more like a shrub than a forb. As an annual, however, it lives only one year, leaving behind the woody skeleton of its branches that rolls away in the wind, distributing seeds. Many alien grasses alter the fire regime of rangeland or desert scrub, destroying native plant species that are not fire adapted, and in turn displacing the animals dependent on that ecosystem. These include the infamous cheatgrass (Bromus tectorum) that plagues western grazing lands, lowering the nutrient value of rangeland and injuring livestock with their sharp awns. The feathery plumes of fountain grasses (Pennisetum spp.) and Pampas grass (Cortaderia selloana) that make them desirable as ornamental plants in the garden often make it difficult to convince horticulturalists of the harm those plants can do when they escape

xviii n GENERAL INTRODUCTION into the natural landscape, where they displace native plants and create fire hazards. Dense stands of giant reed (Arundo donax), with vast intertwined root systems, clog stream channels, altering hydrology and water flow. Several vines grow so efficiently that they completely cover the ground and overtake shrubs and even tall trees. Probably the best known is kudzu (Pueraria montana), which blankets acres of land in southeastern states, not only smothering vegetation but breaking trees and utility lines with the weight of the vines and foliage. Alien swallow-worts (Cynanchum spp.) endanger monarch butterflies because eggs laid on the plants, in the absence of the butterfly’s preferred host, do not survive. Japanese dodder (Cuscuta japonica), a parasite just beginning to gain a foothold in California, poses such a significant threat, not only to natural landscapes but also to crops, that it could affect international trade of crop seeds. Among the 160 or so aquatic plants that are nonindigenous, the best known and most troublesome invasives are probably waterhyacinth (Eichhornia crassipes) and hydrilla (Hydrilla verticillata). Both species grow into dense mats that alter natural ecosystems, downgrade water quality, impede water transportation, and limit recreational activities. Invasive Mammals Introduced mammals include all domesticated livestock; some of their feral descendents that run free in natural habitats are among the world’s worst invaders. In the continental United States, feral pigs (Sus scrofa) are a particular scourge; on Hawai’i and islands in general, feral goats (Capra hircus) are other voracious destroyers of native plants and the habitats supporting endemic birds and other animals. Other mammals that were never domesticated but nonetheless transported to the United States by humans, either deliberately or accidentally, include such invasive species as the black or roof rat (Rattus rattus), Norway rat (Rattus norvegicus), nutria (Myocastor coypus), and the Indian mongoose (Herpestes javanicus). Introduced birds are some of the better-studied species as well as the animals perhaps most familiar to the American public. The urban Rock Pigeon (Columba livia) is actually a feral bird first brought to the country in colonial times as a food animal. Two other common avian pests in cities and towns today were deliberately released to “enhance” the wild bird fauna of the United States: the House Sparrow (Passer domesticus) and the European Starling (Sturnus vulgaris). The most abundant bird in Hawai’i, the Japanese White-eye (Zosterops japonicus), came from eastern Asia. Reptiles introduced from other continents include the huge Burmese python (Python molurus bivittatus)—now rapidly increasing its numbers in the Everglades and spreading beyond the park boundaries to invade other parts of Florida—as well as the brown anole (Norops sagrei), a small lizard that appears to be spreading out of Florida. Among invasive amphibians is the annoying little Cuban treefrog (Osteopilus septentrionalis), which gets into peoples’ houses, but the most ecologically damaging is a native frog from the eastern United States introduced into western waters, the American bullfrog (Lithobates catesbeianus). As further indication of how aquatic ecosystems have been affected by so-called native transplants like the bullfrog, almost two-thirds of the fishes found in American drainages were introduced by people from other U.S. waterways, sometimes in the same state and sometimes from across the continent. Examples of such native invasive fishes are the alewife (Alosa pseudoharangus) in the Great Lakes, the western mosquitofish (Gambusia affinis) in states west of its native range limits in Texas, and rainbow trout (Oncorhynchus mykiss), native to Pacific drainages but now stocked throughout the United States and indeed much

GENERAL INTRODUCTION n xix

of the world. Alien invasive fish include various Asian carps and such strange creatures as walking catfish (Clarius batrachus) and the northern snakehead (Channa argus). Invertebrates, fungi, and microorganisms pose an even greater challenge when estimating numbers of invasive species. We do not even know how many native species exist in most taxonomic groups. According to one estimate, some 4,500 arthropods have been introduced to the United States, more than 2,500 of them to Hawai’i. The hemlock woolly adelgid (Adelges tsugae) has decimated hemlocks in natural forests and opened forest streams to sunlight, while the Asian longhorned beetle (Anoplophora glabripennis) threatens shade and ornamental trees in New York and Chicago but could become a forest pest on a par with the invasive gypsy moth (Lymantria dispar) if it invades eastern broadleaf deciduous forests. Some invading insects, such as the Formosan subterranean termite (Coptoptermes formosanus), cause devastating structural damage to buildings; while others, such as the common bed bug (Cimex lecturius) and brown marmorated stink bug (Halyomorpha halys), are simply serious annoyances inside man-made structures. Among the more potentially damaging insect invaders are those that could disrupt crop pollination by negatively affecting European honey bees—themselves an introduced (domesticated) species. Africanized honey bees (Apis mellifera scutella) hybridize with European honey bees and take over their hives. Two introduced arachnids, the honeybee tracheal mite (Acarapis woodi) and the varroa mite (Varroa destructor) parasitize bees and lead to the demise of bee colonies. Snails, clams, and mussels are among other significant invertebrate invaders. Zebra mussels (Dreissena polymorpha) can transform freshwater communities and clog water intake and distribution pipes. Their rapid spread through Great Lakes and into the Mississippi River drainage in the 1980s was a major stimulus to the development of interest in exotic species in general in the United States. Invasive fungi are largely associated with diseases affecting trees, such as Dutch elm disease and sudden oak death, but a fungus is also responsible for a disease infecting frogs and toads in many parts of the United States. One of the newest invaders, the fungus Geomyces destructans, is implicated in bat white-nose syndrome, a condition currently ravaging bat colonies in the eastern United States. The smallest of invasive species, the microorganisms, are represented by only three entries in this encyclopedia. Humans have been transporting protists, bacteria, and viruses as long as human migrations have taken place. The human diseases brought by early settlers from overseas—smallpox, influenza, measles, to name a few—decimated Native American populations. More recently, HIV and new strains of influenza have run rampant through the U.S. population. Emerging infectious diseases such as dengue fever or ebola may be just around the corner. These are more appropriately dealt with in a book on epidemiology than one on invasive species. The three organisms chosen for inclusion here have close ties to natural habitats and infect wild animals (as well as, in some cases, humans). Avian malaria threatens rare, endemic birds in Hawai’i. The bacterium Borrelia burgdorferi has a complicated life cycle involving two mammalian hosts and expresses itself as Lyme disease in humans. The West Nile virus infects birds, horses, and humans. It is now controlled in horses by vaccination; its long-term impact on wild bird populations remains to be seen. To put the above information in some perspective, it should be noted that about 200,000 species are believed to inhabit the United States. About 91,000 have been described, leaving a large number of plants, animals, fungi, and microbes yet to be discovered. As of the latest count, plants account for nearly 19,000 of the native species, and vertebrates for about 3,000. (According to one count, there are 1,154 native fishes, 295 amphibians, 311, reptiles, 784 birds, and 428 mammals.)

xx n GENERAL INTRODUCTION Native aquatic species—mussels, fishes, salamanders, and turtles—are quite diverse by global standards, as are habitats for both terrestrial and aquatic life. Nearly one-third of our species are considered at risk, including almost 70 percent of freshwater mussels and more than 50 percent of native crayfishes. Natural vegetation has been removed or greatly altered in more than 60 percent of the land area in the lower 48 states. Experts generally agree that destruction of habitat is the greatest threat to our native species, but that the introduction of nonnative species is the second greatest cause of decline and disappearance of native plants and animals.

The Invasion Process For a nonnative species to gain a foothold and become an abundant and widespread inhabitant in an area beyond its native range, several steps or stages are required. Each step involves overcoming some sort of barrier. Species are normally held in their native ranges by geographic barriers to dispersal, such as an ocean, a different and inhospitable (for them) climate region, a drainage divide, a mountain range, distance, wind or ocean current direction, or some other natural feature of the planet. The first stage, the transport stage, requires getting through or over the unfavorable conditions imposed by what is normally a geographic barrier and entering a new site. Plants and animals have done this successfully on their own over millions of years, either by chance or because changes to the environment weaken or remove the barriers. Thus, species have colonized oceanic islands and moved from one continent to another. When humans began to migrate and then to engage in trade, they accelerated the process by either deliberately or unintentionally providing plants, animals, and microorganisms safe transport to new areas in their provisions, packing materials, ships, and other vehicles. Some organisms became desirable commodities in their own right as exemplified today by the pet trade and horticultural industry. Getting to a new site is only the first step. Once a species has arrived or “been introduced,” it must be able to reproduce and establish a self-sustaining population before it can be in a position to become invasive. Surmounting limitations imposed by small founding population sizes and environmental barriers in the new location are the challenges of the second or establishment stage. Typically, only a small number of individuals of a given species occur in the new area, a factor that by itself makes them vulnerable to extinction. The so-called Allee effect depresses reproductive rates since the few individuals present may be sparsely distributed and have difficulty finding mates, or the sex ratio may be skewed toward one gender or the other, both limiting the number of offspring that can be produced during the first few generations. In many instances, a new species persists in an area only because it is repeatedly introThe three stages of the invasion process, showing population status and duced and not because the spedispersal patterns in each. cies is reproducing at the site.

GENERAL INTRODUCTION n xxi

Since the new environment will not be identical to that of the native range, the species may need time to adapt to a new climate, substrate, ecological community, or other aspect of the receiving habitat before its success is assured. If a population does not evolve, it remains highly localized or goes extinct. Even when the demographic and environmental barriers are overcome, it can take 10–25 years for a new species to become numerous enough for people to detect its presence. Success in the establishment phase means reproduction occurs regularly and not only sustains the population, but allows for population growth. The species nonetheless remains near the initial point of introduction at this stage. When the number of individuals increases, the tendency is for a species to expand its distribution area—that is, to spread. Eventually, it will have to overcome local geographic barriers to dispersal. As it spreads into new regions in its adopted home, it enters the invasive stage and begins to produce viable offspring at some distance from the original place of introduction. During the invasive stage, a species continues to increase in abundance and expand its range. Typically, it will first occupy sites disturbed by human activities (such as farmland and settlements) and then be found in seminatural and natural ecosystems. If the new species is perceived to harm or change native ecosystems, it may be deemed officially an “invasive species.” Some ecologists prefer that infliction of ecological and economic harm on the recipient region be considered an additional, fourth stage in the invasion process. Species can spread without causing harm, as has happened with the Cattle Egret. It is frequently stated that, on average, about 10 percent of species actually move from one stage to the next. This means that one in ten of those transported to a new area actually survives and will be found outside of captivity or other controls (i.e., is introduced). One in ten of those will establish self-replacing populations (i.e., become established), and one in ten of established species will spread and become invasive. The result is that very few species arriving in areas they previously have not occupied pass through all the barriers and become invasive. Most species fail to gain even a temporary foothold, let alone invade new regions. Studies have shown that this so-called “tens rule” describes the history of nonindigenous terrestrial vertebrates, fishes, insects, mollusks, and plant pathogens in the continental United States fairly well, but fails to accurately describe nonnative birds in Hawai’i, where more than half of all birds known to have been introduced have become established. It should be noted that the original work that proposed the tens rule focused on plants introduced into the United Kingdom; 10 percent was the average of a range running from 5 to 20 percent. Research examining only those vertebrates coming into the United States from Europe determined that 25 percent became invasive. At this point, it remains unknown how many actually can be expected to succeed, or what makes a species a successful invader, or what allows a native ecosystem to resist, accommodate, or succumb to invasive alien species. For species that do become “invasive,” the process proceeds in a typical pattern. Initially, only a few individuals are spotted in a new area. There is a long lag time before, suddenly, what seemed like an innocuous new member of an ecological community explodes in numbers (irrupts) and becomes a major nuisance or pest and may even begin to transform native ecosystems. Very often, at least in non-island situations, after the initial irruption, the nonindigenous population declines; and the native system accommodates the newcomer. When this happens, the exotic becomes a naturalized member of the community. Recognition of stages in the invasion process helps resource managers design control and mitigation programs. The easiest and most cost-effective control scheme is to intercept arrivals and prevent establishment and/or spread in the first place. This involves detecting incoming species through inspection and quarantines. Constant monitoring is necessary to

xxii n GENERAL INTRODUCTION measure the success or failure of such measures. Once a population is growing and spreading, management becomes problematic and eradication nearly impossible. Pathways of Introduction The means by which species are introduced into new areas are known as pathways. These are generally separated into deliberate or intentional pathways and accidental or unintentional pathways (Table 1 and Table 2). Escapes from confinement or captivity may be thought of as a third, hybrid pathway in which the initial importation was intentional, but the release of free-living individuals or populations was an accident. Generally speaking, most plants and vertebrates have been introduced deliberately; most invertebrates and microorganisms arrived by accident. Plants naturally disperse by sending forth spores and seeds and, for a few, seedlings or parts capable of sprouting vegetatively. These propagules are transported by wind, ocean and stream currents, or animals to places beyond the parent plant and sometimes beyond the range limits of the species. If they land in new territory, they may or may not survive and establish a colony. Humans may have first changed the dispersal process for some plants (and animals) by creating disturbed habitats around campsites and unintentionally carrying seeds on their bodies or in their digestive tracts—just as other animals do. They also harvested and stored seeds and deliberately transported them as they moved from site to site. Some plants adapted to the new dispersing agent and became “camp-followers,” showing up unbidden at each new settlement. Cannabis sativa (marijuana) was such a plant in the Old World. The precursors of many crops may have acted similarly. Mammals such as the dog and pig may have also joined the retinue of people on the move along with arthropods such as cockroaches, lice, silverfish, and other such species that came to live in close association with human beings. Once domesticated crops and livestock were available, people deliberately transported them to far-off places. Seeds and cuttings were traded first among neighboring villages and later to distant shores. With rafts and sailing ships, people helped terrestrial and freshwater species overcome the geographic barrier of the sea. Plants and animals were carried intentionally and accidentally around the world, especially by Europeans and Polynesians. As seagoing technology improved, more distant parts of the planet became connected. Sailing ships were pretty much confined to the natural routes determined by wind and current. But sea-lanes were cut across these old routes when steamships came of age. Seaports were the first point of entry for many species new to an area. Accidental travelers were hidden in the dry or solid ballast of ships under sail. Others, such as shipworms, burrowed in the wooden hulls. During the colonial period, the flow of goods ran largely from the Americas to Europe. Ships from England, France, Spain, and Holland sailed without full loads and took on needed ballast at their home ports. The ballast was offloaded at the port of destination, and if nonnative species had survived the journey, they might become established near wharves and piers and at ballast dumping grounds. Botanists looking for “new” species hunted in these locations. Seeds and insects also stowed away in the hay and straw carried aboard ships as packing material or as fodder and bedding for livestock. Rats climbed the mooring lines at one port to sail to and disembark at another. Everything was on the move. From seaports, a few new arrivals were able to move inland along the canals built to tie the port city to its hinterland. Purple loosestrife (Lythrum salicaria), for example, a plant that came to dominate marshes in New England, was first collected from wetlands near the Erie and Delaware-Ruritan canals. Railroads penetrated even farther inland; their right-of-ways

GENERAL INTRODUCTION n xxiii

Table 1. Examples of Invasive Species That Have Been Introduced by Intentional Pathwaysa Aesthetic amenities, sentiment, or nostalgia

Aquarium trade

Bait bucket releases Biological controls

Bioterrorism (potential) Botanical gardens

Domestic use (dyes, fish poisons)

Erosion control/bank stabilization

Food and beverage

Forage fish Furbearers Livestock abandonment

Livestock forage or fodder

Medicinal herbs or seasonings

European Starling (Sturnus vulgaris) House Sparrow (Passer domesticus) Ornamentals, including but not limited toLantana (Lantana camara) Multiflora rose (Rosa multiflora) Strawberry guava (Psidium cattleianum) Wisterias (Wisteria sinensis, W. floribunda) Common salvinia (Salvinia minima) Hydrilla (Hydrilla verticillata) Lionfish (Pterois volitans) Nightcrawler (Lumbricus terrestris) Rusty crayfish (Orconectes rusticus) Common myna (Acridotheres tristis) Grass carp (Ctenopharyngodon idella) Mosquitofish (Gambusia affinis, G. holbrooki) Multicolored Asian lady beetle (Harmonia axyridis) Indian mongoose (Herpestes javanicus) Infectious diseases Bush honeysuckles (Lonicera spp.) Japanese barberry (Berberis thunbergii) Velvet tree (Miconia calvescens) Common mullien (Verbascum thapsus) Dyer’s woad (Isatis tinctoria) Yellow toadflax (Linaria vulgaris) Australian pine (Casuarina equisetifolia) Giant reed (Arundo donax) Ice plant (Carpobrotus edulis) Japanese knotweed (Fallopia japonica) Kudzu (Pueraria montana) Asian clam (Corbicula fluminea) Chinese mitten crab (Eriochor sinensis)b Chinese mystery snail (Cipangopaludina chinensis malleata) Fire tree (Morella faya) Golden apple snail (Pomacea canaliculata) Himalayan blackberry (Rubus armeniacus) Northern snakehead (Channa argus) Alewife (Alosa pseudoharengus) Nutria (Myocastor coypus) Feral goat (Capra hircus) Feral horse (Equus caballus) Feral pig (Sus scrofa) Buffelgrass (Pennisteum ciliare) Cogon grass (Imperata cylindrica) Gorse (Ulex europaeus) Common St. Johnswort (Hypericum perforatum) Garlic mustard (Alliara petiolata) Giant hogweed (Heracleum mantegazzianum) Japanese hops (Humulus japonicus) (Continued )

xxiv n GENERAL INTRODUCTION

Table 1. (Continued) Packing material

Pet abandonment

Pet trade

Research Sport fishing Timber/reforestation/firewood Wildlife habitat or food Windbreaks/fencerows

a

Japanese stilt grass (Microstegium vimineum) Princess tree (Paulownia tomentosa) Smooth cordgrass (Spartina alterniflora) Burmese python (Python molurus bivittatus) Feral cat (Felis silvestris catus) Nile monitor (Varanus niloticus) Burmese python (Python molurus bivittatus) Giant African snail (Achatina fulica) Nile monitor (Varanus niloticus) African clawed frog (Xenopus laevis) Gypsy moth (Lymantria dispar) Brown trout (Salmo trutta) Rainbow trout (Oncorhynchus mykiss) Carrotwood (Cupaniopsis anacardioides) Melaleuca (Melaleuca quinquenervia) Chinese lespedeza (Lespedeza cuneata) Russian olive (Elaeagnus angustifolia) Melaleuca (Melaleuca quinquenervia) Russian olive (Elaeagnus angustifolia) Tamarisk (Tamarisk chinensis, T. ramosissima)

See table “Pathways of Introduction for Plants,” in Volume 2, for a more complete listing of plant pathways. Probable means of introduction.

b

became avenues of expansion for weedy plants, while other organisms rode the rails as hitchhikers in cargo and packing materials to almost all parts of the country. Airplanes now reach the most isolated places, so nowhere is immune to the introduction of nonnative species. Sometimes military traffic is implicated in the transport of unwanted species to American shores. Perhaps the most notorious example is the arrival of the brown tree snake (Boiga irregularis) on the U.S. territory of Guam after World War II. But a noxious weed, Canada thistle (Cirsium arvense), had also moved on Union military steamships during the American Civil War, reaching its southern limits at the Virginia town of Remington. More recently, the Argentine ant (Linepithema humile) arrived in Hawai’i on military ships during World War II, and the Formosan subterranean termite (Coptotermes formosanus) reached Houston, Texas, on ships returning from the Pacific theater. Shipping remains an important pathway for the entry of new species. Fouling organisms such as lacy crust bryozoan (Membraniphora membranacea), chain tunicates (Botrylloides violaceus), and colonial tunicates (Didemnum vexillum) made their way to U.S. waters in this manner. Today, seawater is used as ballast, and both larval and adult aquatic organisms, plants as well as animals, have been transported from one port across an ocean to another port, where the ballast water is discharged. The zebra mussel (Dreissena polymorpha) and the spiny water flea (Bythotrephes longimanus) both presumably made their way to the Great Lakes in this manner. Canal construction opened the Great Lakes to invasion by such fish as sea lamprey (Petromyzon marinus) and round goby (Neogobius melanostomus). The shipment of used tires on cargo ships provided shelter and breeding sites for Asian tiger mosquitoes (Aedes albopictus), allowing their entry into the United States.

GENERAL INTRODUCTION n xxv

Table 2. Examples of Invasive Species That Have Been Introduced by Unintentional Pathwaysa Ballast and bilge water discharge

Asian green mussel (Perna viridis) Common reed (Phragmites australis spp. australis) Eurasian watermilfoil (Myriophyllum spicatum) Purple loosestrife (Lythrum salicara) Quagga mussel (Dreissena rostriformes bugensis)b Smooth cordgrass (Spartina alterniflora) Spiny water flea (Bythotrephes longimanus) Zebra mussel (Dreissena polymorpha) Crop seed/plant contaminants Canadian thistle (Cirsium arvense) Cheatgrass (Bromus tectorum) Prickly Russian thistle (Salsola tragus) Quackgrass (Elymus repens) Yellow starthistle (Centaurea solsititialis) Dry (solid) ballast Earthworms Common periwinkle (Littorina littorea) Escapes from aquaculture American bullfrog (Lithobates catesebianus) Bighead carp (Hypophthalmichthys nobilis) Giant salvinia (Salvinia molesta) Grass carp (Ctenopharyngodon idella) Water chestnut (Trapa natans) Waterhyacinth (Eichhornia crassipes) Escapes from fur farms Nutria (Myocastor coypus) Escapes from gardens Chocolate vine (Akebia quinata) and most others that originated as ornamental plants Escapes from pet owners Feral cat (Felis silvestris catus) Monk Parakeet (Myopsitta monachus) Mute Swan (Cygnus olor) Escapes from research labs Africanized honey bee (Apis mellifera scutellata) Gypsy moth (Lymanatria dispar) Fish stock contaminants African clawed frog (Xenopus laevis) New Zealand mud snail (Potamopygrus antipodarum)b Hull fouling Chain tunicate (Botrylloides violaceus) Colonial tunicate (Didemnum vexillum) Lacy crust bryozoan (Membranipora membranacea) Ocean currents Asiatic colubrina (Colubrina asiatica) West Indian marsh grass (Hymenachne amplexicaullis) Round goby (Neogobius melanostomus) Removal of natural barriers once Sea lamprey (Petromyzon marinus) separating bodies of water Zebra mussel (Dreissena polymorpha) (e.g., canal construction) Stowaways in cargo Asian tiger mosquito (Aedes albopictus) Stowaways in clothing, bedding, and Common bed bug (Cimex lectularis) luggage Stowaways in equipment, including Canada thistle (Cirsium arvense)a Formosan subterranean termite (Coptotermes military formosanus) Argentine ant (Linepithema humile) Stowaways in grain shipments Argentine ant (Linepithema humile) Stowaways in packing materials Asian longhorned beetle (Anoplophora glabripennis) Brown marmorated stink bug (Halyomorpha halys) (Continued )

xxvi n GENERAL INTRODUCTION

Table 2. (Continued) Stowaways in wood products, including firewood Stowaways on live plants, bulbs, or root balls

Stowaways on ships

a

Dutch elm disease fungus (Ophiostoma novo-ulmi) Emerald ash-borer (Agrilus planipennis) Glassy-winged sharpshooter (Homalodisca vitripennis) Hemlock wooly adelgid (Adelges tsugae) Coqui (Eleutherodactylus coqui) Chestnut blight fungus (Cryphonectria parasitica) Earthworms Japanese beetle (Popillia japonica) Red imported fire ant (Solenopsis invicta) Black rat (Rattus rattus) Cuban treefrog (Osteopilus batrachus) Norway rat (Rattus norvegicus)

See table “Pathways of Introduction for Plants,” in Volume 2, for a more complete listing of plant pathways. Probable means of introduction.

b

Most fungal pathogens arrive with their natural host plants. In the case of the chestnut blight fungus (Cryphonectria parasitica), live plant material was involved. Dutch elm disease arrived on veneer logs. Fungi may also be inadvertently transported in soil and in root balls. Insects, too, infest plants, including wood products, seed supplies, and grain shipments. Terrestrial vertebrates are mostly imported and transported deliberately. Amphibians and reptiles are often valued as bait and pets and used for biomedical research. They may also hitchhike on plants; the coqui (Eleutherodactylus coqui), which has invaded Hawai’i, is a case in point. Nonnative birds have been released as game animals, but most come in as pets and either are released or escape captivity. Many of the more troublesome invasive mammals were deliberately imported as livestock and then deliberately released to the wild (e.g., goats and pigs). Some, such as the Indian mongoose (Herpestes javanicus), were deliberately released as potential biological controls for agricultural pests. Terrestrial invertebrates have been introduced as aquarium novelties, food, pets or ornamentals, and biological control agents. Freshwater aquatic vertebrates (primarily fish) are often deliberately stocked in ponds and streams for sport fishing or as future food sources. Some (e.g., alewives) were released to serve as forage fish for larger game fishes. Invasive aquatic amphibians and reptiles tend to result from pet releases, bait bucket releases, or biological control efforts. Contamination of fish stock by the African clawed frog (Xenopus laevis) led to the establishment of that amphibian in parts of California, but American bullfrogs in western waters stem from releases for food and escapes from aquaculture facilities.

Impacts Invasive species are associated with a variety of ecological, economic, public health, and aesthetic impacts. Sometimes, whether these are positive or negative lies in the eye of the beholder. Usually “impact” is assumed to be negative, and known or potentially negative impacts are the reasons why invasive species are receiving so much attention in the twenty-first century. Indeed, the official definition of “invasive” in the United States includes reference to the harm a species can or does do. Yet it should be remembered that many

GENERAL INTRODUCTION n xxvii

Table 3. Potential Ecological Impacts of Invasive Speciesa Genetic

Individual Population Community Ecosystem

Change in genetic information in a native species through introgression Hybridizing with native species to produce offspring (or new species) that outcompete parents Changes in foraging, pollination, or reproductive behavior Reductions in population size; niche shifts; local extinction Changes in species composition and interactions Changes in nutrient cycles and disturbance regimes

a

See table, “Impacts of Invasive Plants,” in Volume 2, for the complete listing of impacts of invasive plant species.

species are initially introduced because someone foresees a benefit, be it a beautiful blossom, a challenging game animal, a fascinating pet, or a way to control a pest or ameliorate an environmental problem. Ecological Impacts in Natural and Semi-natural Ecosystems As new species spread into the wild and semi-wild habitats of the United States, they have the potential to affect life in our forests, grasslands, and deserts at all biological/ecological levels (Table 3). Native organisms may respond as individuals to a new predator or competitor by altering their behavior. A case in point is the avoidance of some rodents to areas infested by the red imported fire ant. As a result, the mice may forage in less protected areas and become more vulnerable to predation by owls. Individual organisms can also be affected by introduced pathogens, predators, or competitors for limited resources to the extent that the impact becomes evident at the population level, when increased mortality rates threaten the survival of the entire population of a given organism. Avian malaria threatens to decimate several endemic honeycreepers in Hawai’i. West Nile virus caused significant population declines in songbirds such as crows and chickadees when it first spread through eastern states. In the Great Lakes, the round goby (Neogobius melanostomus) displaces native fish such as the mottled sculpin (Cottus bairdi) from its customary spawning grounds and competes with it and other fish for food. Certainly the most notorious recent invader is the predatory brown tree snake, which arrived in Guam sometime between the end of World War II and 1952 and, in the next 20 years, caused the extinction of 10 species of native forest birds and decimated lizards, causing the local extinction of 4 species. In addition, the brown tree snake is implicated in the loss of two species of bat from Guam. While the example of the brown tree snake is unusually dramatic and illustrative of what can happen when a new predator is introduced to an island previously lacking predators, it does serve as a cautionary tale of how wrong things can go. The zebra mussel (Dreissena polymorpha), through its rapid population growth and ability to grow on the shells of native unionid mussels, can physically overwhelm the host and reduce its access to nutrients. Among plants, spotted knapweed (Centaurea stoebe), a perennial forb, is an introduced competitor species. It produces an allelopathic chemical that depresses the germination or growth of native plants, such as the endemic Mt. Sapphire rockcress (Arabis fecunda), and thereby preserves a greater share of light, water, and nutrients for the invader.

xxviii n GENERAL INTRODUCTION Native populations may also be affected at the genetic level through hybridization and introgression. Hybridization involves the cross-breeding of members of two species. When viable offspring are produced, they may exhibit hybrid vigor and grow faster or larger than either parent and reproduce more quickly than either. If sterile offspring are produced, the parent species have wasted their gametes, a practice that may be costly if their numbers are already low. The rainbow trout (Oncorhynchus mykiss), a native transplant to western waters, produces fertile offspring when it mates with the California golden trout (O. mykiss aguabonita) and the threatened Paiute cutthroat trout (O. clarki seleniris). The hybrid offspring of rainbow trout and golden trout can backcross with both parent species and contaminate the gene pool of golden trout by introducing genes of rainbow trout, a process known as introgression. Through this means the native genotype can disappear. Smooth cordgrass (Spartina alterniflora), another native transplant to California, readily hybridizes with the native California cordgrass (Spartina foliosa). The first-generation hybrids have higher growth rates and greater reproductive success than either parent. The hybrids also tolerate a broader range of salinity and invade open mudflats, changing the physical environments in an estuary. Loss of one or more species, as well as the addition of new species, has repercussions for an entire ecological community. Mutualistic relationships such as predator/prey and pollinator/host can be disrupted. Niche shifts can occur as new species are accommodated. Where the brown anole is present, the native green anole (Anolis carolinensis), which customarily seeks prey on the ground or lower regions of tree trunks, forages higher in the tree canopy. Chestnut blight fungus (Cryphonectria parasitica) essentially eliminated the American chestnut from the tree layer of eastern forests. The relative abundance of other trees in the forests changed as white oak (Quercus alba), chestnut oak (Q. prinus), and red oak (Q. rubra) increased in the absence of chestnut. The red imported fire ant has changed the composition of ant communities in areas it has invaded, which in turn may have reduced the dispersal of seeds and thereby affected the plant community as well. Competition for nutrients, water, shelter, or breeding grounds most affects those natives already threatened with extirpation from other forces. Among the more than 950 species listed as endangered or threatened in the United States, some 400, or about 42 percent, are believed to be at risk in part due to the impacts of invasive species. Interestingly, despite the demise of some species, at the local level, species richness usually increases, as invaders more than make up for the loss of natives. When abiotic as well as biotic elements are affected, impacts are occurring at the ecosystem level. Two important ecosystem-level changes involve nutrient cycles and disturbance regimes. By filtering such huge amounts of water, dense populations of zebra mussel increase the amount of nitrogen and phosphorus in the water column and reduce the amount of carbon, which migrates down to the bottom-dwellers in the mussels’ pseudofeces. On Hawai’i, a plant alters the nitrogen cycle, with ecosystem-wide consequences. The fire tree (Morella faya) fixes nitrogen from the atmosphere, which allows it—unlike any native trees—to live on the nitrogen-poor volcanic substrates of the islands. Fire trees add nitrogen to the soil and provide suitable conditions for a variety of other plants to colonize the area, thereby giving rise to a whole new community of plants. On western rangelands, the dominance of cheatgrass has altered the disturbance regime from one where fires occurred on average once every 6–10 years to a burn cycle of 3–5 years. Such frequent fires eliminate shrubs, forbs, and native grasses and produce a monoculture of cheatgrass, an annual grass with low forage value. At a regional or landscape scale, the mixing of species from all over the globe leads to the homogenization of the world’s biota and a loss of global biodiversity. While locally, the total

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number of species may increase, the same species tend to be added everywhere. At the same time, geographically restricted and unique species tend to be disappearing. This impoverishment of the variety of life on earth is viewed with alarm, for homogenization is occurring at all levels—genetic, species, community, and ecosystem—potentially interfering with ecosystem functioning, ecosystem services, and the ability to evolve and adapt to changing environmental conditions. Furthermore, the world becomes a less interesting place as a great sameness spreads across not only our human-made townscapes and cityscapes, but the natural world as well. The impacts of new invasive species are often not as much of a problem as initially feared. A case in point is the Monk Parakeet (Myiopsitta monachus), which had the potential of becoming a major agricultural pest based on the habits of its extinct relative, the Carolina Parakeet (Conuropsis carolinensis). However, the Monk Parakeet has not spread beyond urban areas, where many people are pleased to have these colorful birds visit their feeders. Unfortunately, it is still impossible to predict which introduced species will become invasive and which invasive species will become major ecological problems.

Economic Impacts of Invasive Species Estimates of the costs of invasive species to the United States are commonly reported at well over $100 billion a year, but it is impossible to know the exact figure, which is likely much higher (Pimental et al. 2000; Pimental et al. 2004). It is difficult to put a dollar value on ecological damages or to separate the financial impacts of the combination of factors affecting agriculture, forestry, fisheries, industry, land values, and human well-being, not to mention the price of control and measures directed at preventing introductions, managing invasive species, and implementing remediation measures to repair the damage. In agriculture, direct damage to crops and pastures affect yields and the quality of the product, which in turn can have repercussions on market value. Weeds, insects, and pathogens cost agriculture about $25 billion each year in lost production and another $3 billion for pesticides to control them (Pimental et al. 2000). Measures set up to protect plant and animal life and human health in the United States can become trade barriers and violate World Trade Organization (WTO) agreements, causing costly boycotts among international buyers. The inspections, quarantines, monitoring, and response to introduced insects and pathogens are all expensive but necessary to protect our food supply as well as our farmers. Forestry suffers financial loss not only when trees sicken and die, but also when quarantines prevent sales of wood products. Some 9 percent of lumber, pulpwood, and other forest products are thought to be lost to insect damage at an annual cost of $7 billion. The “Slow the Spread Program” for gypsy moth costs the federal government $8–10 million a year, with additional funds provided by affected states (Tobin 2008). Similar programs are needed for the emerald ash borer (Agrilus planipennis) and other invasive insects. The green crab (Carcinus maenas) is assumed to have caused the demise of the soft shell clam (Mya arenaria) fishery in New England in the 1950s and is also implicated in declines of the commercially important northern quahog (Mercenaria mercenaria), a scallop (Argopecten irradians), and other shellfish with annual harvests worth $44 million in 2000 (Perry 2000). Fouling damage by Asian clams (Corbicula fluminea) in the United States reportedly causes $1 billion a year. The damage by zebra mussels and control of those mollusks at raw water-using and electricity-generating industries in the Great Lakes region are estimated to cost more than $100 million a year (Wisconsin Department of Natural Resources, 2004). Other Great Lakes invaders affect the recreation industry in the region, where losses from sport fishing

xxx n GENERAL INTRODUCTION alone reach an estimated $200 million a year. In Florida, hydrilla clogs waterways and costs $14.5 million a year to control, but there are still financial impacts on the recreation and tourism industries (Pimental et al. 2000; Pimental et al. 2004). Public Health and Well-Being Impacts The most obvious impacts to human health are new pathogens. Global epidemics are expected to become more common with ever-increasing international travel and the globalization of world trade. Such pathogens, past and future, are not covered in this encyclopedia, but they have followed or will follow the same pathways as other invasive species. For some, their virulence depends on finding reservoirs and transmitters among both native and nonnative animals, as in the case of the West Nile virus and the bacterium that causes Lyme disease. A warming climate and invasive mosquitos likely mean the establishment of (currently) tropical diseases like dengue fever in the near future; but the ubiquity and rapidity of air travel opens the U.S. population to all sorts of emerging infectious diseases. A host of simply annoying species have invaded the United States. Asian multicolored lady beetles and brown marmorated stink bugs are two recent examples, while the common bed bug represents a very old traveler now experiencing a resurgence. For folks living in parts of Hawai’i, the noisy coqui can be added to the list, and for people in Florida, the Cuban treefrog lurking in the toilet fits the bill. Such annoyances can be expensive. The din of calling coquis can lower property values. Bug-bitten customers sue hotels and landlords, adding to the costs incurred in trying to eradicate bed bugs.

Invasion Science: A Brief History The seminal work in the scientific study of biological invasions is generally considered to be Charles S. Elton’s 1958 book, The Ecology of Invasions by Animals and Plants, which called attention to some of the most damaging of invaders in various parts of the world. Among featured invasive organisms were the chestnut blight fungus, which had ravaged forests in the eastern United States, and the sea lamprey, which had rapidly spread through the Great Lakes after the opening of the Welland Canal and decimated native fisheries. He described the impact of the American smooth cordgrass on the tidal flats in his native England, where it had hybridized with another cordgrass (Spartina maritima) to create a new species now known as common cordgrass (S. anglica). The hybrid was replacing both parent species and spreading quickly in wetlands on both sides of the English Channel. (Today, smooth cordgrass is causing similar problems in California.) He also noted how the European Starling had expanded its range across the United States and Canada in little more than 60 years after the first pairs had begun to breed in New York’s Central Park. Elton’s compendium obviously drew on earlier work by others, including classic papers by M. T. Cooke (1928) on the spread of the starling between 1891 and 1926 and by J. C. Phillips (1928) on the history of the spread of nonnative birds across the continent. Probably the earliest records of European plants growing in North America were published by the English traveler John Josselyn in 1672, when he catalogued plants observed in New England. Nonetheless, Elton’s work was especially influential, and he became the “Father of Invasion Ecology.” He had sounded the alarm about the disruptions to native ecosystems that can or could occur from successful invaders and called for renewed efforts in the conservation of native biodiversity, in studying the effects of invasive species, and in learning how best to control them and increase the resistance of both natural and human-dominated ecosystems to invasion.

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For those with a more “objective,” less value-driven perspective on invasive species, Joseph Grinnell’s 1919 paper, “The English House Sparrow Has Arrived in Death Valley: An Experiment in Nature,” is a harbinger of the study of invasives as a way to understand basic biogeographical, ecological, or evolutionary processes. Three papers by Richard Johnston and Robert Selander (1964, 1973, 1973) demonstrated that evolution in nonnative populations could be fast. They focused on the House Sparrow, which in a little more than 100 generations had diverged into distinct regional morphs based on size and plumage, displaying well-known biogeographic patterns described by Bergmann’s Rule and Gloger’s Rule, respectively. In 1964, H. G. Baker and G. L. Stebbins convened a conference on “The Genetics of Colonizing Species” and published contributed papers the following year. The 1960s also saw publication of the paradigm-changing book The Theory of Island Biogeography by Robert MacArthur and E. O. Wilson, which modeled how new species fit into existing communities, envisioning an equilibrium number of species on an island that meant that a new colonizer would cause the extinction of a previously established species. Experimental work by Daniel Simberloff and others tested this hypothesis, which dominated ecological research and thought for a couple of decades. On the conservation/management side of the invasive species issue, George Laycock’s 1966 Alien Animals set the tone. Laycock condemned the negative consequences and the human foibles associated with transplanting animals to new locations and strongly advocated against future introductions. Laycock helped bring exotic animals in general to the attention of the public and to resource managers, but may also have biased opinions against all nonnative species. Nonetheless, he stimulated research on nonnatives at a time when scientists were focusing their efforts on supposedly pristine or natural ecological systems. By the 1970s, many scientific journals began to accept articles on invasive species, although some range and wildlife management journals still refused manuscripts on nonnatives. Invading plants and animals increasingly became important research subjects in efforts to discover and understand ecological and evolutionary patterns and processes. International interest in invading species as modifiers of natural communities with the potential to drive or at least exacerbate system-wide changes was growing at the same time research was developing in the United States. In the early 1980s, the Scientific Committee on Problems of the Environment (SCOPE), part of the International Council of Scientific Unions (ICSU), launched a program on the “Ecology of Biological Invasions.” The program sponsored scientific meetings in Great Britain, South Africa, Australia, and the Netherlands, as well as a major symposium in Asilomar, California, and a final convention to synthesize results in Hawai’i in 1986. This global initiative resulted in 15 volumes, including Ecology of Biological Invasions of North America and Hawaii, edited by H. A. Mooney and J. A. Drake (1986). The program addressed two questions that remain at the core of invasion ecology today: what makes a good invader, and what determines whether an ecosystem is prone to, or resistant to, invasion. Invasion ecology had gained a separate space within ecology by the beginning of the twenty-first century, as attested to by a spate of recent textbooks and other works devoted to invasion ecology or invasion biology (e.g., Cadotte et al. 2006; Lockwood et al. 2007; Ruiz et al. 2003; and Sax et al. 2005). Increasingly, invasive species were also being seen as a component of global environmental change, expected to both affect and be affected by climate change, altered nutrient cycles and disturbance regimes, and changing land-use patterns. Another project of SCOPE, Invasive Species in a Changing World (Mooney and Hobbs 2000), highlighted some of these problems and also brought attention to the implications of social views, monetary costs, and the global economy to the management and control of invasive species.

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The Human Factor Species that are invasive today depended on human choices, values, activities, and systems for their initial introduction as well as establishment and further spread. As outlined above, almost all arrived in their receiving habitats as a consequence of their association with humans. (The Cattle Egret is a major exception and, according to some definitions, may not really be “invasive.”) They have followed people from place to place either surreptitiously or as desired members of the human entourage. Most gained their first footholds in or near human habitation or sites of commerce and then found suitable habitats in areas where native plant and animal communities had been disturbed or destroyed by forest clearing, cultivation, domestic livestock grazing, or urban development. In continental situations in particular, their successful entry into wild and semi-wild ecological communities is more likely when some native elements have already been removed or weakened by, for example, predator control, fire suppression, selective grazing, trampling, or a changing climate. Invasive species reflect us: our history of colonization, exploitation, and trade; our changing technology; our human curiosity and aesthetics. Even our love of life and freedom come into play when we release domesticated and pet animals to the wilds. How one views invasive species and deals with them also reflects human values. Individual rights, property rights, animal rights, the right to make a living, all influence whether or not we take measures to prevent introductions, eradicate populations before they begin to spread, or manage species that are beyond the stage where eradication is possible. Some of the largest offenders today in terms of bringing new species into the country are the pet trade and horticultural/nursery trade. Inspection and quarantine are expensive, and it is difficult to prove cost savings from species that do not make it through our ports of entry and to gain public support for such measures. Conflicting viewpoints between conservationists and animal rights groups can make management programs unwieldy at best. But who is right? It depends on what Americans want and value as the natural heritage they pass to future generations. Informed decision making is paramount. People should at the very least know the risks and trade-offs. In the entries contained in the two volumes of this encyclopedia, we try to present a sample of species, pathways, and impacts—actual and potential—so the reader can be better able to make these decisions. Many problems arise because we simply do not understand or are unaware of the consequences of our actions. The species accounts that follow will help the reader identify invasive species and learn some of the ways each of us can slow their spread or best manage them as fellow inhabitants of our land. The choice to do something or nothing is ours.

References Baker, H. G., and G. L. Stebbins, eds. The Genetics of Colonizing Species. New York: Academic Press, 1965. Benson, A. J. “Documentation over a Century of Aquatic Introduction in the United States.” In Nonindigenous Freshwater Organisms: Vectors, Biology, and Impacts, edited by R. Claudi and J. H. Leach, 1–31. Boca Raton, FL: Lewis Publishers, 1999. Cited in Lockwood, Julie L., Martha F. Hoopes, and Michael P. Marchetti. Invasion Ecology. Oxford: Blackwell Publishing, 2007. Cadotte, Marc William, Sean M. McMahon, and Tadashi Fukami, eds. Conceptual Ecology and Invasion Biology: Reciprocal Approaches to Nature. Invading Nature, vol. 1. Dordrecht: Springer, 2006. Cooke, M. T. “The Spread of the European Starling in North America (to 1928).” Circular of the U.S. Department of Agriculture 40: 1–9, 1928. Davis, M. A. “Invasion Biology 1958–2005: The Pursuit of Science and Conservation.” In Conceptual Ecology and Invasion Biology: Reciprocal Approaches to Nature, edited by Marc William Cadotte, Sean M. McMahon, and Tadashi Fukami, 35–64. Invading Nature, vol. 1. Dordrecht: Springer, 2006.

GENERAL INTRODUCTION n xxxiii Elton, Charles S. The Ecology of Invasions by Animals and Plants. London: Chapman and Hall, 1958. Evans, Edward A. “Economic Dimensions of Invasive Species,” Choices, 2003. http:// www.choicesmagazine.org/2003-2/2003-2-02.htm. “Executive Order 13112 of February 3, 1999. Invasive Species.” Federal Register 64, no. 25 (February 8, 1999). http://www.invasivespeciesinfo.gov/laws/execorder.shtml. “Exotic, Invasive, Alien, Nonindigenous, or Nuisance Species: No Matter What You Call Them, They’re a Growing Problem.” Great Lakes Environmental Research Laboratory, NOAA, 2007. http:// www.glerl.noaa.gov/pubs/brochures/invasive/ansprimer.pdf. Federal Noxious Weed Act of 1974. Public Law 93-629. Sections 2801–2814, enacted January 3, 1975. (Superseded by the 2000 Plant Protection Act, except for Sec. 2814.) Fritts, Thomas H., and Dawn Leasman-Tanner. “The Brown Treesnake on Guam: How the Arrival of One Invasive Species Damaged the Ecology, Commerce, Electrical Systems, and Human Health on Guam: A Comprehensive Information Source.” U.S. Geological Survey, Fort Collins Science Center, 2001. http://www.fort.usgs.gov/resources/education/bts/bts_home.asp. Grinnell, J. “The English House Sparrow has Arrived in Death Valley: An Experiment in Nature.” American Naturalist 53: 468–472, 1919. Huennecke, L. “SCOPE Program in Biological Invasions: A Status Report.” Conservation Biology 2: 8–10, 1988. “Injurious Wildlife.” Branch of Invasive Species, U.S. Fish and Wildlife Service. http://www.fws.gov/ fisheries/ans/ANSInjurious.cfm. “Invasiveness in Exotic Plants: Immigration and Naturalization in an Ecological Continuum,” In Conceptual Ecology and Invasion Biology: Reciprocal Approaches to Nature, edited by Marc William Cadotte, Sean M. McMahon, and Tadashi Fukami, 65–106. Invading Nature, vol. 1. Dordrecht: Springer, 2006. Johnston, R. F., and R. K. Selander. “Evolution of the House Sparrow. I. Intrapopulation Variation in North America.” The Condor 69: 217–258, 1967. Johnston, R. F., and R. K. Selander. “Evolution of the House Sparrow. II. Adaptive Differentiation in North American Populations.”Evolution 25: 1–28, 1971. Johnston, R. F., and R. K. Selander. “Evolution of the House Sparrow. III. Variation in Size and Sexual Dimorphism in Europe and North and South America.” American Naturalist 107: 373–390, 1973. Johnston, R. F., and R. K. Selander. “House Sparrows: Rapid Evolution of Races in North America.” Science 144: 548–550, 1964. Josselyn, John. New England’s Rarities, discovered in Birds, Beasts, Fishes, Serppents, and Plants of that Country, 1672. Reprint, Boston: William Veazie, 1865. Republished, Bedford, MA: Applewood Books, n.d. Laycock, George. The Alien Animals. The Story of Imported Wildlife. New York: Ballantine Books, 1966. Lockwood, Julie, Martha F. Hoopes, and Michael P. Marchetti. “An Introduction to Invasion Ecology,” Invasion Ecology, 1–17, 2007. Lockwood, Julie L., Martha F. Hoopes, and Michael P. Marchetti. “Ecological Impacts of Invasive Species.” Chapter 9 of Invasion Ecology. Oxford: Blackwell Publishing, 2007. Lockwood, Julie L., Martha F. Hoopes, and Michael P. Marchetti. Invasion Ecology. New York: Blackwell Publishing, 2007. Mooney, H. A., and J. A. Drake, eds. Ecology of Biological Invasions of North America and Hawaii. New York: Springer-Verlag, 1986. Mooney, H. A., and R. J. Hobbs, eds. Invasive Species in a Changing World. Washington, DC: Island Press, 2000. Murphy, Helen T., Jeremy VanDerWal, Lesley Lovett-Doust, and Jon Lovett-Doust. “Invasiveness in Exotic Plants: Immigration and Naturalization in an Ecological Continuum,” In Conceptual Ecology and Invasion Biology: Reciprocal Approaches to Nature, edited by Marc William Cadotte, Sean M. McMahon, and Tadashi Fukami, 65–106. Invading Nature, vol. 1. Dordrecht: Springer, 2006. “Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990.” As Amended through P.L. 106–580, December 29, 2000. http://www.anstaskforce.gov/Documents/nanpca90.pdf. Osborn, Liz. “Number of Native Species in the United States.” Current News Nexus. Research News and Science Facts, 2010. http://www.currentresults.com/Environment-Facts/Plants-Animals/ number-of-native-species-in-united-states.php.

xxxiv n GENERAL INTRODUCTION Perry, Harriet. “Carcinus maenas.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2008. http://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=190. Phillips, J. C. “Wild Birds Introduced or Transplanted in North America.” Technical Bulletin of the U.S. Department of Agriculture, 1928. Pimentel, D., L. Lach, R. Zuniga, and D. Morrison. “Environmental and Economic Costs of Non-Indigenous Species in the United States.” Bioscience 50(1): 53–65, 2000. Pimentel, David, Rodolfo Zuniga, and Doug Morrison. “Update on the Environmental and Economic Costs Associated with Alien-Invasive Species in the United States,” 2004. Available online at http:// ipm.ifas.ufl.edu/pdf/EconomicCosts_invasives.pdf. Richardson, David M., Petr Pysˇek, Marcel Rejma´nek, Micahel G. Barbour, F. Dane Panetta, and Carol J. West. “Naturalization and Invasion of Alien Plants: Concepts and Definitions.” Diversity and Distributions 6: 93–107, 2000. Ruiz, Gregory M., and James T. Carlton. Invasive Species: Vector and Management Strategies. Washington, DC: Island Press, 2003. Sax, Dov F., John J. Stachowicz, and Steven D. Gaines. Species Invasions. Insights into Ecology, Evolution, and Biogeography. Sunderland, MA: Sinauer Associates, Inc., 2005. Simberloff, D. “A Rising Tide of Species and Literature: A Review of Some Recent Books on Biological Invasions.” Bioscience 54: 247–54, 2004. Stein, Bruce A., Lynn S. Kutner, and Jonathan S. Adams. Precious Heritage: The Status of Biodiversity in the United States. New York: Oxford University Press, 2000. Tobin, Patrick C. “Cost Analysis and Biological Ramifications for Implementing the Gypsy Moth Slow the Spread Program.” USDA, Forest Service, Northern Research Station, General Technical Report NRS-37, 2008. http://nrs.fs.fed.us/pubs/9238 Williamson, Mark, and Alastair Fitter. “The Varying Success of Invaders.” Ecology 77(6): 1661–66, 1996. Wisconsin Department of Natural Resources. “Zebra Mussels (Dreissena polymorpha),” n.d. http://dnr .wi.gov/invasives/fact/zebra.htm.

n Preface Invasive species have gained our attention in different ways. Susan Woodward, who wrote about invasive microorganisms, fungi, and animals in Volume 1, had her interest in invasive animals first sparked as a student of biogeography in the 1970s. Birds such as the European Starling and House Sparrow were featured in textbooks to demonstrate how animals spread in an environment that was new to them or how quickly they evolved adaptations to varying local conditions across a whole continent. Graeme Caughley’s work on irruptions of red deer in New Zealand was new, and the modeling of invasions and management of exotics in their infancy. As a doctoral student at UCLA, she studied feral burros along the lower Colorado River, viewing them as an example of humans “changing the face of the earth” (the buzzwords of those days) by transporting domesticated and wild animals around the world. Under contract to the Bureau of Land Management (BLM) at that time, she collected baseline data on population dynamics, diet, home range size, and other aspects of burro behavior and ecology that would help that agency devise policies and practices for the animals’ management. With an applied aspect to her work, she straddled what has become two main perspectives on invasive species in general: an academic interest in the science of invasions and a management interest in preventing arrivals, eradicating or controlling the spread of those species that were able to establish populations, and managing those whose numbers and distribution were for all practical purposes already beyond eradication. Joyce Quinn, a biogeographer whose research dealt with distribution of plants and their relationships with the natural environment, such as climate and soils, wrote the invasive plants section in Volume 2. In spite of her experience, she found that researching and writing this book led her to learn more. Some plants that she had thought were an integral part of the “natural” landscape, such as common mullein, are actually alien plants that had become naturalized and are now widespread in the United States. She notes: Several years ago, an uninvited plant sprouted unexpectedly in my yard. I tried for years to get rid of it, dutifully pulling off the little sprouts as they emerged. After four or five years, I gave up and decided to let the plant grow. In a couple of years, it became an attractive tree about 10 ft. (3 m) tall. It had smooth speckled bark, long lacy compound leaves, and clusters of small purple star-shaped flowers. As I was doing research for this Encyclopedia, I discovered that my new plant was a chinaberry tree. While attractive, it had few redeeming qualities so I decided to eliminate it. A friend helped me saw the trunk, about 8 in. (20 cm) in diameter, slightly below ground level. I immediately poured undiluted glyphosate on the freshly cut stump, thinking that was the end of it. I paid no attention until four months later when I saw a 6 in. (15 cm) sprout! I sprayed it with herbicides, but another sprout soon emerged. I sprayed again, but at the time of this writing, I still do not know if I have managed to kill the invader. I fear that it will be an on-going process. If I have had such trouble with just one alien invasive plant, the challenges that land managers, conservationists, and agriculturalists have in battling invasive species seem insurmountable.

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Scope The purpose of the Encyclopedia of Invasive Species is to provide an introduction to the species, issues, and management options involved with invasive animals, fungi, microorganisms, and plants. The number of plants and animals introduced into the United States is staggering. Only a relatively few establish self-sustaining populations, and very few of these actually become invasive (in the scientific sense of greatly and rapidly expanding their range in the United States). Still, there are hundreds of invasive species—too many to be included in a reference book of this sort. For many species, much remains to be learned, and it is premature to develop full entries for them, but this still leaves many to choose from. In selecting the 168 species for inclusion in the Encyclopedia, we have tried to offer a wide spectrum of invasive species that includes some present in the United States from colonial times, and some that have just been detected; some that completed their spread across the country long ago, and others that are in the midst of rapid population growth and range expansion. We also wanted to include some species that are found throughout the country, and some that are limited to a region or single state. For animals, we aimed to include representatives from all major classes of vertebrates and a good variety of invertebrates. The reader will find common, well-known invaders and others that may be a surprise. We also wanted to showcase a few fungi, especially those that have been major transformers of urban, suburban, and natural forests, and at least acknowledge the presence of invading microorganisms with a tiny sample of those threatening the health of native animals and, in some cases, humans as well. Finally, we wished to have a geographically broad selection of invasive animals, with all 50 states and Puerto Rico having some members of their nonindigenous fauna represented. Florida, Hawai’i, and California have the largest numbers of officially recognized invasive species. Residents of these states will undoubtedly find nonnative organisms causing significant impact in natural and artificial ecosystems missing from our accounts. This was necessary in order to include some organisms limited to other states. For plants, we also tried to include a little bit of everything. Volume 2 addresses a variety of growth forms, ranging from aquatic plants to trees and vines, and all regions of the United States. Some plants are widespread throughout the country, while others are localized. Many plants were deliberately brought to the United States as ornamentals or for some useful characteristic, while others were accidentally introduced. The length of entries dedicated to each species is variable. The taxonomic relationships of some plants and similar species are not always clearly defined. Some plants, for example, hybridize so freely that it becomes difficult to distinguish different species. A few accounts of invasive plants treat two or more related species in the same entry because their effects and management are similar. As with animals, we could always find “one more” species that should be included, but it was not possible to include all. A wealth of information from various sources can be accessed by the reader wanting to know more. The General Bibliography at the end of Volume 2 has a list of recommended resources, including websites. The Encyclopedia is specifically meant for high school and college students, but addresses many of the informational needs of the curious naturalist, horticulturalist, or any homeowner or environmentally concerned citizen who is interested in the origins and consequences of invasive plants and animals. Although some invasive species have been part of the landscape of the United States for literally hundreds of years, the wide-reaching effects of most are only beginning to become realized. Some invasive species are detrimental to native ecosystems and threaten biodiversity, others are more economically damaging to crops and livestock, and a few pose a danger to

PREFACE n xxxvii

human health. Invasive species are a major part of current global environmental change. Experts consider them the second-greatest threat to native species after habitat destruction and fragmentation. The control and interdiction of invasive species coupled with the damage some incur on crops, pastures, livestock, native ecosystems, and human health and wellbeing costs billions of dollars each year. The invasive species problem is dynamic—as those in the Mid-Atlantic states weathering their first onslaught of the brown marmorated stink bug know well—and endlessly fascinating.

How to Use the Encyclopedia Volume 1 begins with an introduction to inform the reader of the nature and scope of issues related to invasive species in the United States. Separate sections deal with the terminology related to invasive species, the invasion process from an ecological point of view, the pathways by which nonnative species have been and continue to be introduced to the United States, some of the ecological and economic impacts of invasives, and a brief outline of the history of modern invasion science. A final section of the introduction describes the human factors that determine what species come in, where they succeed, and if and how they are managed. The introduction is followed by 88 entries describing microorganisms, fungi, invertebrates, and vertebrates. Entries are arranged alphabetically within major taxonomic groups. The species described represent the large number introduced and invasive in the continental United States, Hawai’i, and Puerto Rico. Each entry in both volumes includes the following elements, unless noted otherwise: Native Range Distribution in the United States Description Related or Similar Species Introduction History Habitat Diet (animals only) Life History (animals, fungi, and microorganisms only) Reproduction and Dispersal (plants only) Impacts Management Selected References Additionally, each entry in both volumes is accompanied by at least one photograph and maps that show the original and invasive range of the species in question according to the best information available. Often range maps are, by necessity, approximate. This is especially true for organisms not native to the United States or Europe, where biological surveys are more complete than on other continents. In Volume 1, the entries are followed by a list of state-by-state occurrences of invasive animals, fungi, and microorganisms; a glossary; and an index to both volumes. Volume 2 begins with a brief overview of invasive plants in the United States, which loosely follows the organization within species accounts, describing in general the scope of

xxxviii n PREFACE the invasive plant problem, including the ways, both intentional and accidental, that plants were brought into the country; and some of the effects invasive plants have on native plant and animal species, natural ecosystems, agricultural or fishing industries, recreational activities, or human health. The ways in which invasive plants reproduce and expand their range is summarized, as is information on management and prevention of invasive plants species. A sidebar on herbicides accompanies the overview. The 80 entries on invasive plants are arranged by growth form categories: aquatics, forbs, graminoids, shrubs, trees, and vines. Photographs of each species show different parts of the plant. Interesting facets of a plant’s use or history or of strategies attempted for its control are related in sidebars. Several supplementary lists follow the invasive plant entries to provide background information, and various tables summarize plant data in different, easily accessible ways, including a table of common and scientific names of both plants and animals briefly mentioned in the text of Volume 2, and a list of organizations concerned with invasive plants in the United States. Two tables of noxious or invasive plants, one organized by state and the other by species, as well as a table of species listed by type of impact are also available. Volume 2 concludes the set with these appendices to the Encyclopedia: a list of American species that are invasive in other parts of the world; a list of federal laws related to the prevention and management of invasive species; international agreements and conventions dealing with invasive species; and the IUCN/SCC Invasive Species Specialist Group’s list of 100 of the “World’s Worst Invasive Alien Species,” with an indication of those covered in the Encyclopedia. The glossary, a selected bibliography of classic and contemporary writings and online information sources, and the index to the set complete Volume 2. It is our hope that our efforts will stimulate thought and make the natural world more accessible to the general public. Informed readers can help make the decisions that will curtail the spread of species that have only recently arrived, prevent the arrival of yet others, and manage those that are currently invasive

Acknowledgments Both authors thank the photographers who graciously allowed their photos to be used, often donating them, or sometimes providing them at a reduced fee. They deserve our special thanks for giving life to the species descriptions. Bugwood.org and its associated personnel at the Center for Invasive Species and Ecosystem Health, University of Georgia, deserves special mention as a clearinghouse for providing informational sources and photographs. Joyce Quinn prepared the excellent maps for the species accounts. Each author is most appreciative of the other’s contributions to the development of the project, the overall organization of the volumes, and constructive critiques of text and illustrations throughout the manuscript preparation process. We complement each other and work well as a team. We acknowledge Kevin Downing, originally of Greenwood Press and now serving the broader ABC-CLIO community as editorial operations manager, who initiated the proposal for the Encyclopedia set, and David Paige of ABC-CLIO, who guided us through subsequent discussions and organizational details. Anne Thompson, development editor, later offered guidance in the specifics of the manuscript, and Erin Ryan helped with the specifications for the illustrations. We thank all four for creating a positive and flexible working environment and offering valuable suggestions all along the way.

n Alphabetical List of Invasive

Microorganisms, Fungi, and Animal Entries

Entries in the encyclopedia are arranged by categories. Following are the entries in Volume 1 in alphabetic order. African Clawed Frog (Xenopus laevis) Africanized Honey Bee (Apis mellifera scutellata) Alewife (Alosa pseudoharengus) American Bullfrog (Lithobates catesbeianus) Argentine Ant (Linepithema humile) Asian Clam (Corbicula fluminea) Asian Green Mussel (Perna viridis) Asian Longhorned Beetle (Anoplophora glabripennis) Asian Swamp Eel (Monopterus albus) Asian Tiger Mosquito (Aedes albopictus) Australian Spotted Jellyfish (Phyllorhiza punctata) Avian Malaria (Plasmodium relictum capistranoae) Bat White-Nose Syndrome Fungus (Geomyces destructans) Bighead Carp (Hypophthalmichthys nobilis) Black Rat (Rattus rattus) Brown Anole (Norops[=Anolis] sagrei) Brown Marmorated Stink Bug (Halyomorpha halys) Brown Trout (Salmo trutta) Burmese Python (Python molurus bivittatus) Cattle Egret (Bubulcus ibis) Chain Tunicate (Botrylloides violaceus) Chestnut Blight Fungus (Cryphonectria parasitica) Chinese Mitten Crab (Eriocheir sinensis) Chinese Mystery Snail (Cipangopaludina chinensis malleata) Chytrid Frog Fungus (Batrachochytrium dendrobatidis) Colonial Tunicate (Didemnum vexillum) Common Bed Bug (Cimex lectularius) Common Myna (Acridotheres tristis) Common Periwinkle (Littorina littorea)

xl n ALPHABETICAL LIST OF INVASIVE MICROORGANISMS, FUNGI, AND ANIMAL ENTRIES Coqui (Eleutherodactylus coqui) Cuban Treefrog (Osteopilus septentrionalis) Dutch Elm Disease Fungi (Ophiostoma novo-ulmi and O. ulmi) Emerald Ash Borer (Agrilus planipennis) Eurasian Collared-Dove (Streptopelia decaocto) European Earthworms (Lumbricus terrestris, L. rubellus, Aporrectodea caliginosa, Dendrobaena octaedra, and others) European Starling (Sturnus vulgaris) Feral Burro (Equus asinus) Feral Cat (Felis silvestris catus) Feral Goat (Capra hircus) Feral Horse (Equus caballus) Feral Pig (Sus scrofa) Formosan Subterranean Termite (Coptotermes formosanus) Giant African Snail (Achatina fulica) Gizzard Shad (Dorosoma cepedianum) Glassy-Winged Sharpshooter (Homalodisca vitripennis) Golden Apple Snail (Pomacea canaliculata) Grass Carp (Ctenopharyngodon idella) Green Crab (Carcinus maenas) Green Iguana (Iguana iguana) Gypsy Moth (Lymantria dispar) Hemlock Woolly Adelgid (Adelges tsugae) Honeybee Tracheal Mite (Acarapis woodi) House Finch (Carpodacus mexicanus) House Mouse (Mus musculus) House Sparrow (Passer domesticus) Indian Mongoose (Herpestes javanicus) Japanese Beetle (Popillia japonica) Japanese White-Eye (Zosterops japonicus) Lacy Crust Bryozoan (Membranipora membranacea) Lionfish (Pterois volitans /P. miles) Lyme Disease Bacterium (Borrelia burgdorferi) Monk Parakeet (Myiopsitta monachus) Mosquitofish (Gambusia affinis and G. holbrooki) Multicolored Asian Lady Beetle (Harmonia axyridis) Mute Swan (Cygnus olor) Naval Shipworm (Teredo navalis) New Zealand Mud Snail (Potamopyrgus antipodarum) Nile Monitor (Varanus niloticus)

ALPHABETICAL LIST OF INVASIVE MICROORGANISMS, FUNGI, AND ANIMAL ENTRIES n xli

Northern Snakehead (Channa argus) Norway Rat (Rattus norvegicus) Nutria (Myocastor coypus) Quagga Mussel (Dreissena rostriformis bugensis) Rainbow Trout (Oncorhynchus mykiss) Red Imported Fire Ant (Solenopsis invicta) Rock Pigeon (Columba livia) Round Goby (Neogobius melanostomus) Rusty Crayfish (Orconectes rusticus) Sea Lamprey (Petromyzon marinus) Silver Carp (Hypophthalmichthys molitrix) Spiny Water Flea (Bythotrephes longimanus) Spotted Tilapia (Tilapia mariae) Sudden Oak Death (Phytophthora ramorum) Varroa Mite (Varroa destructor) Veined Rapa Whelk (Rapana venosa) Walking Catfish (Clarias batrachus) West Nile Virus (West Nile Virus) White Pine Blister Rust (Cronartium ribicola) Zebra Mussel (Dreissena polymorpha)

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n Microorganisms n Avian Malaria Scientific name: Plasmodium relictum capistranoae Family: Plasmodiidae Native Range. Eurasia. The exact place of origin is unknown, but genetic evidence strongly suggests it arose somewhere in Eurasia, and it is known to infect Eurasian birds such as House Sparrows (Passer domesticus) and Common Mynas (Acridotheres tristis), both of which have been introduced to Hawai’i. Distribution in the United States. Hawai’i. Avian malaria is most common at elevations of 3,000–5,000 ft. (900–1,500 m) on the moist windward sides of all the main islands. Description. This parasitic protozoan requires microscopic examination of blood and tissues for identification. The clinical symptoms of malaria in Hawai’i’s endemic honeycreepers (Drepaniidae) include weight loss, lethargy, lack of appetite, and high death rates. Infected birds will have a prominent sternum or breast bone (keel). Necropsies reveal enlarged, chocolate-brown or black livers and spleens and thin, watery blood; up to 50 percent of circulating red blood cells are infected by the microorganism. Related or Similar Species. Other Plasmodium species are responsible for malaria in reptiles, birds (including poultry), and mammals, including humans. Different subspecies of P. relictum are known to infect birds in other parts of the world. Introduction History. The introduction of avian malaria to Hawai’i required the arrival of both the parasite and a vector. The mosquito vector was unintentionally brought to Hawai’i in 1826. It seems to have reached Maui first and may have come in water barrels aboard a ship sailing from Mexico. The hundreds of exotic birds released in the islands likely led to the accidental introduction of Plasmodium relictum in the early twentieth century. Species such as the House Sparrow and Common Myna, from Europe and India, respectively, are the most probable sources. With no prior exposure to the parasite, native birds quickly fell victim to avian malaria. Habitat. Avian malaria occurs where its vector species live. In Hawai’i, the vector is the southern house mosquito (Culex quinquefasciatus), itself an introduced species. This mosquito is most common at elevations below 5,000 ft. (1,500 m), and avian malaria is most prevalent among native birds in moist lowland forests. Cool temperatures prevent the development of mosquito larvae, and temperatures below 55°F (13°C) restrict the development of malarial parasites in adult mosquitoes. Recent studies, however, suggest that the mosquito—and hence the disease—is beginning to occur at higher elevations in the islands. This may be a product of warmer summer temperatures. The disease is found in dry habitats if water is seasonally available. Mosquito breeding sites occur in standing water, including ditches, stock ponds, the artificial containers commonly found in human settlements, tree fern cavities, pools in intermittent streams, and wallows made by feral pigs. Cavities in lava flows also trap water and create corridors for mosquitoes to move between forest fragments.

2 n MICROORGANISMS Life History. P. relictum undergoes both sexual and asexual reproduction at different stages of the life cycle in both its bird and mosquito hosts. When a mosquito bites an infected bird, it will ingest gametocytes, the male and female reproductive cells of the protozoan. In the gut of the mosquito, the gametocytes produce encysted cells that develop into motile spores (sporozoites) which move to the salivary gland and are injected into a bird when the mosquito again feeds on blood. Thus the sporozoites are the infectious stage of the protozoan. In the bird, sporozoites attack red blood cells and develop within them, replicating their nuclei and other organelles. The resulting multinucleated cells, called schizonts, grow and cause the red blood cell that they have infected to burst. The schizonts then break apart and release single-nucleus daughter cells (sporozoites) into the bloodstream. (These daughter cells produce toxins that, in human malaria, cause the characteristic Top: The place of origin of the protozoan that causes avian malaria is chills and fever.) Impacts. Avian malaria inunknown, but somewhere in Eurasia is likely. Bottom: Avian malaria currently only affects birds in Hawai’i. fects passerine (perching) birds, which in Hawai’i include the Hawaiian Crow (Corvus hawaiiensis) and honeycreepers, a group of 57 birds (half of which are now extinct), all believed to have evolved from a single finch-like ancestor and all endemic to the islands. The introduction of avian malaria to the Hawaiian Islands has been implicated in a modern wave of population reductions, range restrictions, and possibly extinction of a number of Hawai’i’s rare birds. Only native bird species, having evolved during a long period of isolation, seem to be deleteriously affected by the parasite. For some of them, such as the ‘I’iwi (Vestiaria coccinea) and the Maui ‘Alauahio (Paroreomyza montana), infection by the malaria parasite is almost always fatal. Other honeycreepers, such as the ‘Omao (Myadestes obscurus), show greater resistance to the disease. Lowland populations of Hawai’i ‘Amakihi and O’ahu ‘Amakihi (Hemiagnathus virens complex) in the Puna area of the Big Island appear to have evolved some resistance to avian malaria since coming into contact with the parasite. Most surviving honeycreepers today live at elevations above 5,000 ft. (1,500 m), where both Culex mosquitoes and the malaria protozoan have difficulty reproducing. The

LYME DISEASE BACTERIUM n 3

Akiapola’au (Hemignathus munroi), for example, once occupied forests as low as 1,600 ft. (500 m) on the island of Hawai’i, but the remnant populations of this endangered species are now found only in high-elevation forests. On Maui, the six remaining endemic passerines (four are extinct) inhabit a narrow strip of high-elevation rainforest on the slopes of Haleakala¯ Volcano. Efforts are underway to reestablish some of Hawai’i’s threatened and endangered honeycreepers in protected patches of high-elevation forest. If mosquitoes continue to expand their distribution into higher and higher elevations as climate changes, these efforts could be doomed. Development of resistance to Plasmodium relictum seems to be occurring in some populations and may help some bird species survive; however, resistant birds still harbor the parasite and can transmit it to mosquitoes. They serve as reservoirs for the disease, further threatening vulnerable species. Management. Control measures are directed at the vector, the southern house mosquito. The most effective way of preventing the disease from spreading is to eliminate or reduce populations of the mosquito by removing man-made habitats of standing water where the mosquito breeds or applying Bt (Bacillus thuringiensis israelensis) to impoundments such as horse watering troughs that cannot be removed. This attack on mosquitoes has also targeted feral pigs (see Vertebrates, Mammals, Feral Pig), which dig in the forest floor in search of food and leave behind depressions that catch rainwater and harbor mosquito larvae. The pigs also push over tree ferns and eat the starchy pith, creating water-holding cavities for mosquitoes to breed in.

Selected References Atkinson, Carter T. “Ecology and Diagnosis of Introduced Avian Malaria in Hawaiian Forest Birds.” USGS FS 2005-3151. Pacific Island Ecosystems Research Center, U.S. Geological Survey, 2005. http://biology.usgs.gov/pierc/Native_Birds/Avian_malaria.pdf. Atkinson, Carter T., and Dennis A. LaPointe. “Plasmodium relictum (Micro-organism).” ISSG Global Invasive Species Database, 2005. http://www.invasivespecies.net/database/species/ecology.asp ?si=39&fr=1&sts. Beadell, Jon S., Farah Ishtiaq, Rita Covas, Martim Melo, Ben H. Warren, Carter T. Atkinson, Staffan Bensch, Gary R. Graves, Yadvendradev V. Jhala, Mike A. Peirce, Asad R. Rahmani, Dina M. Fonseca, and Robert C. Fleischer. “Global Phylogeographic Limits of Hawaii’s Avian Malaria.” Proceedings of the Royal Society B: Biological Science, 272(1504): 2935–44. Published online August 22, 2006. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1639517/. doi:10.1098/ rspb.2006.3671. LaPointe, Dennis A. “Feral Pigs, Introduced Mosquitoes, and the Decline of Hawai’i’s Native Birds.” USGS FS 2006-3029. Pacific Island Ecosystems Research Center, U.S. Geological Survey, 2006. http://biology.usgs.gov/pierc/Fact_Sheets/Pigs_and_mosquitoes.pdf.

n Lyme Disease Bacterium Scientific name: Borrelia burgdorferi Phylum: Spirocheates Native Range. North America and Europe. B. burgdorferi sensu stricto occurs in the United States, while two other strains—B. burdorferi garinii and B. burgdorferi afzelli—are found in Europe. Distribution in the United States. Maine to Virginia; Great Lakes region; northern California.

4 n MICROORGANISMS Description. B. burgdorferi has the characteristic corkscrew appearance of spirochetes in general. Its clinical manifestation as Lyme disease in humans is marked first by a diagnostic bull’s-eye rash that usually surrounds a tick bite and expands with time (erythema migrans). The rash may last for 2–3 weeks and be accompanied by flu-like symptoms. Untreated, stage 2 symptoms develop, including intermittent inflammatory arthritis, facial palsy, and extreme fatigue and malaise. In stage 3 of the disease, inflammation of the brain (encephalitis) and spinal chord (myelitis) and weakening of the lower limbs (paraparesis) occur; symptoms of fibromylagia can develop. The microscopic spirochete is transmitted to humans when they are bitten by infected ticks. In the eastern and midwestern United States, the black-legged or deer tick (Ioxodes scapularis) is the vector; in the Pacific Northwest, the western blacklegged tick (I. pacificus) is Top: The spirochete responsible for Lyme disease is known from both involved. Adult deer ticks are North America and Europe, but the disease was first reported in Europe, teardrop-shaped and 0.1 in. making that continent the more probable place of origin. Bottom: (3 mm) long, about the size of Borrelia burgdorferi infects ticks throughout the lower 48 states, but it is an apple seed. Females, the only most prevalent in the Northeast, western Great Lakes region, and parts ones that seek blood meals, have of northern California. (Adapted from American Lyme Disease black heads and dorsal shields Foundation, “U.S. Maps and Statistics,” http://www.aldf.com/usmap and dark red abdomens. In .shtml.) males, the hard shield or scutum covers the entire back, and the head and whole body are black. The nymphs of these tiny arachnids are about the size of a poppy seed, have black heads and translucent bodies; they are most apt to transmit Lyme disease to people because they are so small that they may not be noticed and removed. Western black-legged ticks are very similar in appearance. Introduction History. Lyme disease was first recognized in 1975 by Dr. Allen Steele of Yale University, when about 50 children in the town of Lyme, Connecticut, developed rashes and joint pain, swelling, and inflammation similar to arthritis. Indeed, the new disease was originally called “Lyme arthritis.” It was soon determined that the symptoms were similar to a tick-borne infection that had been known in Europe since at least 1883, when

LYME DISEASE BACTERIUM n 5

it was reported by the German physician Alfred Buchwald. It was not until 1982, however, that Dr. Willy Burgdorfer discovered the causative agent of the disease in black-legged ticks. The spirochete was named in his honor. Since 1975, the incidence of the disease has increased and spread in the United States, where it is now the most common tick-borne illness. More than 20,000 new cases are reported each year. Ten states account for more than 90 percent of occurrences: Delaware, Maryland, Massachusetts, Minnesota, New Jersey, New York, Pennsylvania, Rhode Island, and Wisconsin. The increasing prevalence of the disease is due to a variety of factors, including better identification and record keeping; encroachment of residential areas into tick habitats; exploding deer and tick populations associated with suburban sprawl and forest fragmentation, as well as reforestation in the northern United States; and the range expansion of black-legged ticks into newly available habitats. Habitat. The tick vectors of Lyme spirochetes inhabit the understory of moist, deciduous forests and open grassy areas with tall vegetation. It is often found along paths and roadsides. Diet. Blacklegged ticks are external parasites on warm-blooded animals. They require a blood meal in order to molt and develop to the next stage of life. Field mice, especially the white-footed mouse (Peromyscus leucopus), serve as important hosts for larvae. Nymphs and adults feed on deer, dogs, and humans. Life History. The bacterium B. burgdorferi circulates between ticks and a variety of vertebrates, each species affecting the survival of the spirochete because of varying competence as host species and different rates of infestation by ticks. Ticks can obtain the spirochete as larvae. Hatching during the summer, a larval tick waits on the ground for a small mammal or bird to come into contact with it, whereupon it attaches to the passing animal and begins feeding, sucking blood for a few days. If the host, most commonly a white-footed mouse, is infected with the pathogen, the larval tick will likely also become infected. (Mice serve as “reservoir hosts”: they easily acquire the spirochete and sustain viable bacteria in their blood, allowing it to increase in numbers. They accept tick larvae again and again, and

A. The corkscrew shape of the Borrelia spirochete. (Centers for Disease Control and Prevention.) B. Black-legged or deer tick (Ioxodes scapularis), the vector for Lyme disease in eastern and central states. (Hardin MD/University of Iowa and CDC, http://www.lib.uiowa.edu/hardin%5Cmd/cdc/ 1669.html.) C. Western black-legged tick (I. pacificus), adult female. This arachnid is the vector for Lyme disease in western states. (Hardin MD/University of Iowa and CDC, http://www.lib.uiowa.edu/ hardin/md/cdc/ticks5.html.)

6 n MICROORGANISMS thereby can transmit the bacteria to other larvae. Mice themselves show no signs of disease.) Once the larva has gorged itself, it will not feed again, but drops off its host and, in the fall, molts into a nymph. Nymphs remain inactive until early the following spring. When the nymphs become active, they wait in ambush on vegetation for a new host to brush past them. They attach to a deer, person, dog, or cat and feed for 4–5 days. If they were already infected with the Lyme spirochete as larvae, they may transmit it to the host. If they were free of infection, they may become infected during this time should the host already carry the pathogen. Peak activity for nymphs is spring and summer, and this is when humans are most apt to acquire Lyme disease. Once the nymph is fully engorged with blood, it drops off the host and molts into an adult. Adults are active throughout the fall and wait on grass or leaf tips about 3 ft. (1 m) above the ground to attach to deer or other larger mammals, including people. Adult deer ticks are most active in late fall, but humans are less apt to become infected at this time of year because the adults are large enough to be seen and picked off before the spirochete can be transmitted. Adult ticks without hosts become inactive when temperatures drop below 45°F (7°C) and typically find shelter in leaf litter on the forest floor. With warming temperatures in early spring, the adults seek a final blood meal, usually on deer, that will allow them to mate. Mating occurs on or off a host. The female lays some 3,000 eggs under leaf litter and then dies, completing the two-year life cycle. Infection of humans by B. burgdoferi requires that a tick be attached for at least 24 hours and more likely for 2–3 days. Only small numbers of the spirochetes occur in a tick until it feeds. With the intake of blood, the bacteria multiply in the tick’s gut. After 2–3 days, they migrate to the salivary glands, where they are injected into the host as the tick completes its feeding. This is why undetected nymphs usually spread the disease to humans. An estimated 85 percent of infected persons received the bacteria from nymphs in the spring; the other 15 percent obtained the infection from adults in autumn. Only about 1 percent of tick bites in an area where Lyme disease is prevalent result in infection. Impacts. Some people are able to clear the infection without developing any symptoms. In others, the bacteria spread through the body and elicit inflammatory responses in the skin (erythma migrans) and joints, tendons, and bursae, especially in the knees, ankles, and wrists. These may be accompanied by fever and general malaise. Untreated, the conditions last a week or more and often reoccur for up to 10 years. The most common neurological condition associated with Lyme disease is facial paralysis, which may last for a couple of months. More serious manifestations of the disease include inflammation of the brain, a form of meningitis presenting as a headache, stiff neck, and sensitivity to light. It can be quite debilitating for a long period of time. Most cases are successfully treated with antibiotics. Management. Control is aimed at preventing infection of humans. People should try to avoid tick habitats, particularly in spring when the nymphs are active. Removal of vegetation that is prime tick, mouse, and/or deer habitat—tall grass, brush, and dead leaves—from housing and work areas is also advisable. Precautions such as wearing light-colored clothing, long-sleeved shirts, hats, and closed shoes, plus tucking pant legs into socks or boots, can delay the attachment of ticks to skin and make them more visible. Insect repellent on clothing and skin (except on the face) also helps. After outdoor activity, a careful body inspection should be done, and any ticks should be removed with tweezers. Deer ticks and western black-legged ticks seek body folds such as armpits, groin, back of the neck, and back of the knee. Shower and wash clothes in hot water. Vaccines to prevent Lyme disease are now available for dogs and cats.

WEST NILE VIRUS n 7

Selected References “Deer Tick Ecology.” American Lyme Disease Foundation, Inc., 2006. http://www.aldf.com/ deerTickEcology.shtml. Meyerhoff, John O. “Lyme Disease.” Medscape, 2009. http://emedicine.medscape.com/article/330178 -overview. Todar, Kenneth. “Borrelia burgdorferi and Lyme Disease.” Todar’s Online Textbook of Bacteriology, 2008. http://www.textbookofbacteriology.net/Lyme.html.

n West Nile Virus Also known as: WNV West Nile Virus Family: Flaviviridae Native Range. Uncertain. West Nile virus was first described in Uganda and then found in other parts of Africa as well as in Europe, Southwest and Central Asia, and Australia. Whether it was native or introduced to these regions has yet to be determined. Distribution in the United States. West Nile virus has been reported in all of the 48 contiguous states, although outbreaks do not occur in every state every year. Description. This small flavivirus consists of a positive-sense single strand of RNA (ribonucleic acid) containing between 11,000 and 12,000 nucleotides. The RNA is surrounded by a protein coat (nucleocapsid) that is encased in a lipid membrane. The complete structure or virion is spherical and measures 40–65 nm in diameter. Related or Similar Species. Other flaviviruses cause human diseases, including St. Louis encephalitis, yellow fever, dengue fever, and Hepatitis C. Introduction History. West Nile virus was first described from Uganda in 1937. Subsequently, it was discovered in many parts of the Old World and in Australia and found to be one of the most widespread flaviviruses in the world. Confirmation of the virus in New York City in 1999 marked its first appearance in the Americas. Early in the spring of 2000, it showed up again in mosquitoes and birds and quickly spread to other parts of the eastern United States. In 2000, it ranged from New Hampshire to North Carolina; by 2001, it had crossed the Mississippi River; and by 2004, it was in every state except Alaska and Hawai’i. The source of the initial introduction is unknown. Genetic studies point to origins in the Mediterranean or Middle East. The strain that reached the United States seems to have evolved into a more virulent form through the mutations of amino acids in a single gene. How it reached the United States is a mystery. Once on the continent, the virus spread geographically in migrating birds. Habitat. West Nile virus cycles between two hosts, birds and mosquitoes. Other vertebrates act as dead-end hosts; for though the virus may cause illness in them, it never reaches high-enough levels in the blood to be transmitted to mosquitoes. The virus thrives in environments where mosquitoes, especially of the genus Culex, breed: wetlands, urban areas with artificial containers that collect rainwater, and wherever else standing water persists for several weeks or more. Recent epidemics are correlated with unusual hot, dry periods. Life History. West Nile virus replicates best in certain bird species that become the major amplification hosts. The virus has been isolated in well over 100 different species. Some are extremely susceptible to infection and die, while others are very tolerant of infection and show no signs of impairment. The West Nile virus is transmitted from bird to bird by

8 n MICROORGANISMS mosquitoes, the most competent vectors in the United States being the southern house mosquito (Culex quinquefasciatus); the northern house mosquito (C. pipiens); the whitedotted mosquito (C. restuans); C. salinarius, a mosquito of salt marshes; and in the western United States, the encephalitis mosquito (C. tarsalis). These mosquitoes feed preferentially on birds, but also feed opportunistically on the blood of other vertebrates and can transmit the disease to humans, horses, and other species. Other mosquitoes such as Culex nigripalpus, a common mosquito in Florida; the Asian tiger mosquito, Aedes albopictus; the inland floodwater mosquito (Aedes vexans); and the eastern treehole mosquito (Ochlerotatus triseriatus) may also spread West Nile virus. Some evidence suggests that squirrels (Sciurus spp.), eastern chipmunks (Tamias striatus), eastern cottontails (Sylvilagus floridanus), and alligators (AlliTop: The West Nile virus was first described in Uganda, but its origins gator mississippiensis) may build remain unknown. Bottom: The West Nile virus has been reported in all up sufficiently high levels of of the lower 48 states. the virus in their blood to serve as reservoirs. Impacts. During periods in 1999 and 2002–2003 when rates of human infection with West Nile virus were epidemic, high mortality rates were experienced among several common songbird species. Indeed, the widespread American Crow (Corvus brachyrhynchos) is so susceptible to fatal infection that dead individuals serve as indicators of the virus’s presence in a given area. In some regions of the country, 45–100 percent of crows died during past outbreaks. Among other birds studied in the eastern United States, sharp population declines correlating with WNV epidemics occurred in the Blue Jay (Cyanocitta cristata), the Tufted Titmouse (Baeolophus bicolor), the American Robin (Turdus migratorius), the House Wren (Troglodytes aedon), the Black-capped and Carolina Chickadee (Poecile atricapillus and P. carolinensis, respectively) and the Eastern Bluebird (Sialia sialis). The Common Grackle (Quiscalus quiscula) was hard hit in Maryland. Others species showed great tolerance. These included Mourning Dove (Zenaida macroura), Northern Cardinal (Cardinalis cardinalis), Baltimore Oriole (Icterus galbula), Chipping Sparrow (Spizella passerina), and

WEST NILE VIRUS n 9

A. Image of West Nile virus particle produced by cryoelectron microscopy. (Purdue University Department of Biological Sciences.) B. The southern house mosquito transmits the West Nile virus from bird to bird. (U.S. Geological Survey.)

Catbird (Dumetella carolinensis). Populations of Blue Jays and House Wrens had rebounded by 2005, after the epidemic in humans had subsided, but populations of other birds remained low. In the western states, Black-billed Magpies (Pica hudsonia), House Finches (Carpodacus mexicanus), and Greater Sage Grouse (Centrocercus urophasianus) have been severely affected. The ecological impacts of rapid changes in bird populations is unknown, but shifts in species abundance and therefore possibly ecosystem functioning can be expected. Crows, for example, are important scavengers and are also predators of the nestlings of other birds and thereby control population sizes. Many humans infected with the West Nile virus will develop no symptoms, but about 20 percent of infected people experience flu-like symptoms, including high fever, headache and body aches, general fatigue, rash, vomiting, and diarrhea. For relatively few—fewer than 1 percent of those known to be infected—the disease is fatal. The virus invades the nervous system and presents as encephalitis, meningitis, limb paralysis, or acute respiratory failure. In horses, the symptoms of West Nile virus include weakness in the hindquarters, tremors, muscle rigidity, and paralysis. Between 1999 and 2002, the disease affected some 20,000 equines in the United States and was fatal in an estimated 38–57 percent of cases. Vaccination became available in 2002, but infection rates remained high. Management. Control measures focus on eliminating breeding sites for the mosquitoes that are the vectors for the virus. This is primarily an urban and suburban problem and

10 n MICROORGANISMS means removing containers such as old tires, drums, bottles, and cans in which standing water accumulates; repairing leaky pipes and outside faucets; unclogging gutters; and replacing water in birdbaths, watering troughs, and the like several times a week. People can minimize their risk of being bitten by mosquitoes by using insect repellent, wearing clothing that covers arms and legs, and minimizing outdoor activity at dusk and dawn when mosquitoes are most active. A vaccine is available for horses, but still under development for humans.

Selected References LaDeau, Shannon L., A. Marm Kilpatrick, and Peter P. Marra. “West Nile Virus Emergence and LargeScale Declines of North American Bird Populations.” Nature 447: 710–13, 2007. doi:10.1038/ nature05829. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “West Nile Virus (Micro-organism).” ISSG Global Invasive Species Database, 2006. http:// www.issg.org/database/species/ecology.asp?si=304&fr=1&sts. Weiss, Rick. “Bird Species Plummeted after West Nile: National Survey Finds Losses Among Many Songbirds.” Washington Post, 2007. http://www.washingtonpost.com/wp-dyn/content/article/ 2007/05/16/AR2007051601032_pf.html. “West Nile Virus.” National Institute of Allergy and Infectious Diseases, 2009. http://www .niaid.nih.gov/topics/westnile/understanding/pages/what.aspx. “West Nile Virus Detected in Arizona.” Agency Directive, Arizona Game and Fish Department, 2003. http://www.azgfd.gov/w_c/diseases_west_nile.shtml.

n Fungi n Bat White-Nose Syndrome Fungus Scientific name: Geomyces destructans Phylum: Ascomycota Family: Heliotiaceae Native Range. Unknown. The fungus associated with bat white-nose syndrome may be native to Europe or may represent a soil fungus that has recently mutated in the northeastern United States to become a pathogen of hibernating bats. Distribution in the United States. Geomyces destructans occurs from Vermont south to Virginia and west into Tennessee and Missouri. It probably also occurs in northwest Oklahoma. Description. This fungus manifests itself as a white coating on the nose, ears, and wing membranes of hibernating bats. The dense covering of fine hyphae can be removed through grooming, but scars often remain. Under a microscope, the fungus is distinguished by asymmetrically curved conidia, the asexually produced spores. These conidia and the fact that the fungus has very low optimal temperatures for growth confirmed G. destructans was a new and separate species in the genus Geomyces. Introduction History. Bat white-nose syndrome was first reported from Howe’s Cave near Albany, New York, during the winter of 2006–2007. Three years later, its presence was confirmed in caves and mines in Connecticut, Massachusetts, New Jersey, Pennsylvania, Vermont, Virginia, and West Virginia. In February 2010, the disease was reported in Tennessee. It has also expanded into eastern Missouri, as well as eastern Canada. Its origins and potential for further spread remain unknown. Habitat. G. destructans proliferates on many organic surfaces in the dark, cool, highhumidity environments of caves and underground mines, where it colonizes the skin of hibernating bats. It fails to thrive at temperatures in excess of 68°F (20°C). Thus this coldloving fungus finds optimal growing conditions in the hibernacula used by nonmigratory bats that must over winter in a dormant state at latitudes above 40° N or at higher elevations in the southeastern United States. Life History. Much is yet to be learned about this recently described fungus. It can grow on a variety of organic substances and seems to persist year round in caves and mines. It apparently becomes established in the skin tissue of bats when their body temperatures are lowered to 35°–50°F (2°–10°C) during torpor in the winter. The hyphae penetrate tissue by entering hair follicles and sebaceous glands. No inflammation or immune response seems to be elicited in the bat. Although G. destructans produces what is known as white-nose syndrome, penetration of the wing membranes by the fungus may be the most detrimental aspect of the disease to bats. Current high mortality rates are one sign that it is a new pathogen that has not achieved a balance with its host. G. destructans is spreading rapidly from bat to bat and hibernacula to hibernacula. Spores easily attach to skin, hair, ropes, and clothing; it is not known for how long they remain viable outside their subterranean home or just how they disperse to other

12 n FUNGI caves. Migrating bats and cavers likely disperse the fungus to new caves and underground mines. Impacts. White-nose syndrome has killed some 500,000 insect-eating bats since it was first discovered in 2006. Dead bats are usually emaciated, but exactly how, or indeed if, the fungus kills them is still to be determined. In addition to the tell-tale white encrustations on ears and wing membranes and around the nose, affected bats display unusual winter behaviors. They tend to come out of torpor much more frequently than normal and fly around the cave or mine in which they have been hibernating or leave the hibernacula during the day to fly around outside. Bats are found closer to the cave entrance than normal, and large numbers of dead bats are clustered near or just outside the entrance. It may be that the fungus is such a skin irritant that it rouses the bats from hibernation. When they arouse from torpor and fly around, they use Top: It is not known if Geomyces destructans originated as a mutation in a vital body fat reserves, which soil fungus native to the northeastern United States or if it is native to cannot be replenished because Europe. Bottom: Areas in the United States where bat white-nose insects are not available for them syndrome had been reported as of June 2010. (Adapted from map by to feed upon during the winter. Cal Butchkoski, Pennsylvania Game Commission.) Ultimately, the bats may starve to death. Infection of the wing membranes may exacerbate the situation since the membranes play important physiological roles in regulating body temperature, blood pressure, water balance, and gas exchange. It may also be that infected bats disturb other nonaffected bats in the colony and rouse them from hibernation, too. Bats that have been sampled as they enter hibernacula in the fall seem to be healthy, strongly suggesting they acquire the pathogen in the winter cave. Currently, six species of bats are known to be affected by white-nose syndrome. The most dramatic losses have been suffered by the little brown bat (Myotis lucifugus), which has undergone population declines of 93 percent in some caves. The Indiana bat (Myotis sodalis), a federally endangered species, has seen declines of 53 percent in certain hibernacula. Other bats affected include northern long-eared bat (Myotis septentrionalis), tri-colored bat

BAT WHITE-NOSE SYNDROME FUNGUS n 13

A. Little brown bat (Myotis lucifugus) affected by white-nose syndrome, Greeley Mine, Vermont. (Marvin Moriarty, U.S. Fish and Wildlife Service.) B. Hibernating bats with white-nose syndrome, New York. (Nancy Heaslip, New York Department of Environmental Conservation.) C. Geomyces destructans infection on wing membrane of bat. (Ryan von Linden/New York Department of Environmental Conservation.)

(Perimyotis subflavus; formerly known as Eastern pipistrelle [Pipistrellus subflavus]), eastern small-footed myotis (Myotis leibii) and big brown bat (Eptesicus fuscus). The fungus has recently been found in caves used by another endangered species, the Virginia big-eared bat (Corynorhinus townsendii virginianus), although white-nose syndrome has not (yet) been reported on this bat. In Tennessee, there is concern that it will affect the endangered gray bat (Myotis grisescens). Most of these bats reproduce slowly, having only a single young each year, so populations are not expected to rebound quickly from the devastating impacts of white-nose syndrome. Such sudden and widespread death among hibernating bats was previously unknown. Lethal fungal skin infections are rare among mammals, but more common among “coldblooded” vertebrates whose body temperatures hibernating bats approximate. Chytridiomycosis in amphibians (see Chytrid Frog Fungus below) may be an analogous condition. Bats have an enormous capacity for consuming flying insects, including moths, mosquitoes, and many plant pests. Their loss would represent a major change in natural, suburban, and agricultural ecosystems in the eastern United States. Management. While direct bat-to-bat transmission of the fungus is difficult if not impossible to prevent, it is likely that humans transfer G. destructans spores from cave to cave, and steps can be taken to reduce or halt that process. The U.S. Forest Service has closed caves and mines to recreational cavers in national forests in 33 states, and many states, caving clubs, and private owners have followed suit. The public should honor all cave closings in affected states and adjoining areas to control the spread of this deadly pathogen. Those entering caves for scientific purposes should carefully decontaminate all clothing and gear

14 n FUNGI with household bleach or commercially available antibacterial cleaners. Ropes and harnesses should not be used at all or, if essential, should be dedicated to use in only a single cave. The U.S. Fish and Wildlife Service has issued containment and decontamination protocols and provides an online listing of cave closures at http://www.fws.gov/northeast/wnscavers.html.

Selected References Gargas, A., M. T. Trest, M. Christensen, T. J. Volk, and D. S. Blehert. “Geomyces destructans sp. nov. Associated with Bat White-Nose Syndrome.” Mycotaxon 108: 147–54, 2009. Available online at http://botit.botany.wisc.edu/toms_fungi/147gargas9-73.pdf. “White Nose Syndrome: Could Cave Dwelling Bat Species in the Eastern US Become Endangered in Our Lifetime?” Bat Conservation and Management, 2010. http://www.batmanagement.com/wns/ wns.html. “White-Nose Syndrome Threatens the Survival of Hibernating Bats in North America.” USGS Fort Collins Science Center, 2010. http://www.fort.usgs.gov/wns/.

n Chestnut Blight Fungus Also known as: Chestnut bark disease fungi Scientific name: Cryphonectria parasitica Synonym: Endothia parasitica Class: Pyrenomycetes Order: Diaporthales Family: Valsaceae Native Range. Mountainous areas of China and Japan. Distribution in the United States. Eastern states throughout the range of the American chestnut (Castanea dentata), roughly from Maine west to Michigan and south to Georgia and Mississippi. It also occurs outside the tree’s range wherever chestnuts have been planted. Description. This fungus causes cankers, localized areas of dead tissue, on the trunks of American chestnut trees. On the surface of the tree, both swollen and sunken cankers form above the infection; the sunken type expands to girdle the tree. Often orange or yellow fruiting bodies the size of pin heads cover the canker. During moist weather, spores ooze out of the fruiting bodies, looking like tiny curled orange horns. Early symptoms of infection include reddish-brown patches on the bark that later develop into cankers. The bark may crack, and yellow fruiting bodies appear on the surface. Leaves on affected branches turn brown, but do not fall from the tree for months. The entire tree above the infection will die as the canker grows, but the roots are not killed. An American chestnut will continue to resprout from the root collar for decades after the above-ground part of the tree has died. Introduction History. The blight was first identified in the United States in 1904 at the Bronx Zoo in New York City. It may have entered the country as early as 1876, when Japanese chestnut trees (Castanea crenata) were first imported. By the end of the nineteenth century, the Japanese species was being offered for sale by most U.S. mail-order nurseries. In 1904, the blight was actually widespread north of Virginia. By 1926, it occurred throughout the natural range of the American chestnut. Its impact had been so devastating that in 1912, the U.S. Congress passed the Plant Quarantine Act, the first legal action to stem the flow of

CHESTNUT BLIGHT FUNGUS n 15

nonnative species into the United States, in an attempt to prevent future catastrophes. The law gave the federal government the authority to establish inspection stations and quarantine areas to intercept and prevent the spread of exotic pests and pathogens. Today, the Animal and Plant Inspection Service (APHIS), part of the U.S. Department of Agriculture, is in charge of these activities. Habitat. In North America, Cryphonectria parasitica occurs almost exclusively in American chestnut trees. It infected mature trees in natural forests as well as those planted as ornamentals, and now attacks the saplings that still sprout from old stumps and root systems. The fungus does also attack Allegheny chinkapin (Castanea pumila) and bush chinkapin (C. alnifolia). Several oaks (Quercus spp.) also serve as hosts; but cankers usually remain small and superficial on them and do not kill the tree. Only the post oak (Q. stellata) seems to be seriously damaged by the fungus. Other trees on Top: The chestnut blight fungus originated in mountain forests of China which chestnut blight has been and Japan. Bottom: The former range of the American chestnut reported include shagbark (Castanea dentata), shown on the map, is a surrogate for the range of the hickory (Carya ovata), red maple blight fungus; although the blight also affects chestnuts planted beyond (Acer rubrum), and staghorn the tree’s native range. (Adapted from Saucier 1973.) sumac (Rhus typhina). Life History. The chestnut blight fungus produces small, sticky spores in the sexual fruiting bodies visible on the bark’s surface. These so-called ascospores are forcibly ejected during warm rains and dispersed by the wind or on the feet of birds and insects. Nonmotile asexual spores called conidia are also produced. The fungal spores enter a tree through wounds or cracks, often at a branch crotch. The junctions of limbs and the trunk are particularly vulnerable because the movement of branches in the wind creates small ruptures in the bark in the crotches. The spores germinate in the inner bark and cambium, where masses of thread-like hyphae (mycelia) form into small brown fans. The cushionlike masses of solid mycelia (stromata) interfere with the flow of nutrients through the phloem and with the growth of the cambium. On American chestnut, stromata can reach densities of 8 per in2 (50 per cm2). First the leaves die, then the branches above the point

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A. Developing cankers on young American chestnut tree. (USDA Forest Service-Region 8-Southern Archive, USDA Forest Service, Bugwood.org.) B. Leaves of the American chestnut. The once-mighty tree is now represented by root sprouts in the understory. (Linda Haugen, USDA Forest Service, Bugwood.org.) C. A row of dead American chestnuts after the blight struck. The split rail fence in the foreground is likely constructed of chestnut timber. (USDA Forest Service-Northeastern Area Archive, USDA Forest Service, Bugwood.org.)

of infection. The sunken cankers can expand enough to girdle the tree within a single growing season and kill the entire above-ground portion of the tree, or it may take several years. C. parasitica continues to live in dead wood, but is unable to enter the roots. Chestnuts continue to resprout for decades. While the sprouts may live for 5–10 years and attain heights of 25 ft. (8.0 m), they rarely live long enough to mature and flower or bear nuts before they, too, succumb to the blight. Impacts. The chestnut blight fungus eliminated the American chestnut as a major tree in eastern forests. These trees were the largest in the broadleaf deciduous forests in the southern Appalachians, where they commonly grew to heights of 60–90 ft. (18–27 m) and diameters at breast height (DBH) of 3–5 ft. (1–1.5 m). Exceptional specimens were 120 ft. (35.6 m) tall and 7 ft. (2 m) in diameter. The crown of a single tree could be nearly 100 ft. (30 m) wide. Its sweet nuts were produced in great abundance every year and nourished deer, turkeys, squirrels, and other wildlife as well as people. The fruits that fell to the ground after the first frost were an important cash crop for many Appalachian families. The wood was slow to decay and was therefore used for building barns, fences, log cabins, furniture, and coffins. Split-rail fences made of chestnut still persist in woodlands grown up in abandoned pastureland. The bark and wood was rich in tannic acids and preferred over the bark of other trees for tanning leather. Large trees with their spreading branches and

CHESTNUT BLIGHT FUNGUS n 17

reliable nut harvests had been favored shade trees in towns and on farms in and beyond the native range of the chestnut. Forest structure and composition changed dramatically with the loss of this major tree in the forest canopy. Various oaks (Quercus spp.), red maple (Acer rubrum), and hickories (Carya spp.) assumed dominance in the forest canopy. By 1940, most large chestnut trees—an estimated 3.5 billion trees—had been killed. Lumber could be salvaged from dead trees for 10 years after the blight, and bark and wood was harvested for tannin until the late 1950s. Standing ghost trees became infested with small boring insects that left pin-sized holes in the wood. This so-called “wormy chestnut” is still valuable whenever it is discovered; it is used largely for making small craft items. IUCN has nominated the chestnut blight fungus as among 100 of the world’s worst invasive species. Management. Control of the chestnut blight fungus has followed two routes, one trying to reduce the virulence of the fungus, and the other trying to increase the resistance of the tree. A strain of the fungus first identified in Italy was discovered that had been weakened by the presence of a virus. The spores of these so-called hypovirulent fungi can be inoculated into cankers on American chestnuts to slow their growth or, for a time at least, have the fungus produce only the swollen, nonlethal type of canker. A drawback of this procedure is that hypovirulent fungi spread much more slowly in nature than the virulent strains. Cross-breeding resistant Asian chestnut species with American chestnut can impart a degree of resistance to the fungus in the hybrid generation. Several researchers are repeatedly back-breeding hybrids with American parents in an attempt to produce a tree with good forest form, high-quality timber, abundant and good-tasting nuts, and resistance to chestnut blight. Some naturally resistant individual American chestnut trees survive both within and outside the original range of the tree. Attempts to graft scions from them to existing root stock are also part of restoration efforts.

Selected References Anagnostakis, Sandra L. “Revitalization of the Majestic Chestnut: Chestnut Blight Disease.” American Phytopathological Society, 2000. http://www.apsnet.org/publications/apsnetfeatures/Pages/ ChestnutBlightDisease.aspx. “Chestnut Blight.” Missouri Botanical Garden, 2001–2010. http://mobot.org/gardeninghelp/plant finder/IPM.asp?code=283&group=39&level=s. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Cryphonectria parasitica (fungus).” ISSG Global Invasive Species Database, 2006. http:// www.issg.org/database/species/ecology.asp?si=124&fr=1&sts. Rellou, Julia. “Chestnut Blight Fungus (Cryphonectria parasitica).” Introduced Species Summary Project, Columbia University, 2002. http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/ inv_spp_summ/Cryphonectria_parasitica.htm. Saucier, Joseph R. “American Chestnut . . . an American Wood. (Castanea dentata (Marsh.) Borkh.).” FS-230, U.S. Department of Agriculture, Forest Service. Washington, DC: U.S. Government Printing Office, 1973. Available online at http://www.fpl.fs.fed.us/documnts/usda/amwood/230 chest.pdf. Treadwell, Judy C. “American Chestnut History.” NCNatural.com, 1996. http://www.appalachian woods.com/appalachianwoods/history_of_the_american_chestnut.htm.

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n Chytrid Frog Fungus Also known as: Chytrid fungus, Bd Scientific name: Batrachochytrium dendrobatidis Order: Rhizophydiales Family: Chytridiaceae Native Range. Unknown. Africa may be the source of this fungus, because the earliestknown case of infection is on a museum specimen of the African clawed frog (Xenopus laevis) collected in 1938. The disease caused by this fungal agent, chytridiomycosis, was endemic to sub-Saharan Africa 23 years prior to its being found elsewhere in the world. However, recent genetic research suggests that chytrid frog fungus may have originated in Japan. Distribution in the United States. Throughout. Description. Chytrid frog fungus is an invisible external parasite of amphibians. Positive identification requires examination of tissue or water and sediment samples in a laboratory. The several symptoms of chytridiomycosis are not unique to this disease but can alert one to the possibility of infection by Batrachochytrium dendrobatidis. These include behavioral changes in the infected animal such as lethargy, inability to right itself if turned on its back, failure to flee from humans, and failure to seek shelter from the sun. Frogs and toads may sit in the water all the time. Redness can appear on the belly skin, and wet skin may slough off. The bodies of toads and frogs can become bloated from retention of fluids. Toe curling, head held in a tucked position, and other signs of mild paralysis may occur. Sudden mass die-offs occur in infected populations. No single symptom applies to all affected species, Top: Africa has been suspected as the place of origin for the chytrid frog fungus, but genetic evidence now points to Japan as the possible source making definitive field identifiarea. Bottom: The chytrid frog fungus is found throughout the United States. cation impossible.

CHYTRID FROG FUNGUS n 19

Related or Similar Species. Batrachochytrium dendrobatidis is the only chytrid fungus known to infect living vertebrates. Other species decompose cellulose and chitin. Introduction History. It is unknown when or how the chytrid frog fungus entered the United States. Two hypotheses are being tested. The first poses that the fungus probably originated in Africa and only began to spread rapidly around the world during the twentieth century. The African clawed frog, a known host, was exported in large numbers for medical research beginning in the 1940s and again in the 1960s and 1970s, when its use in human pregnancy tests became popular. The first documented lethal outbreaks of chytridiomycosis did not occur until 1998, when reports came simultaneously from Australia and Central America. The fungus was not scientifically described and named until 1999. Today, it has been identified on over 350 species of amphibians on all continents except Antarctica. A second hypothesis states that the chytrid frog fungus has been widely distributed, but not recognized, around the world for a very long time, and the sudden outbreaks that began in the late 1990s in disparate locations have been triggered by recent global environmental changes. The synchronous nature of the outbreaks supports this hypothesis, as does evidence from preserved museum specimens and field analyses that show low-level infections without lethal consequences on many amphibian species in the eastern United States. Examination of preserved museum specimens of North American amphibians reveals that the fungus was in the United States long before it gained the world’s attention in the late 1990s. The earliest record dates to 1974 and a leopard frog (Rana pipiens) collected in the Rocky Mountains in Colorado. The fungus was also found on a specimen from the Sierra Nevada in California dating to the same year. (It was found on specimens from Que´bec, Canada, collected in the 1960s.) Whatever its origins, chytrid can be dispersed on live amphibians sold for food, pets, or research animals. The American bullfrog (Lithobates catesbeianus) could be an effective vector, since it is a popular food internationally. Poison dart frogs (Dendrobates spp.) from South and Central America could carry the fungus into zoo collections, where they are prized exhibits. Contaminated habitat material such as water and sediment can transfer zoospores to new bodies of water if lodged in tires or on boots or even possibly in the hooves of livestock. Much research is still needed to unravel the mystery of the distributional history of this fungus. Habitat. This is an aquatic fungus, and it requires water as well as suitable hosts. It will survive in any body of water from streams and lakes to artificial containers. Chytrid frog fungus prefers cooler temperatures (in laboratory trials, it grows best in water temperatures of 63–73°F [17–23°C] and dies at temperatures above 82°F [28°C]) and permanent flowing water. It is more apt to be found in streams than ponds, because the former are cooler and help to transfer spores over long distances. Batrachochytrium dendrobatidis lives on the skin of adult frogs and treefrogs, toads, and lungless salamanders. It is most prevalent on the more heavily keritanized skin of the abdomen, especially near the pelvis, on hind limbs, and on feet. It is also found on the oral discs (the structures surrounding the mouths) of tadpoles. Chytrid frog fungus is found in wild populations as well as among captive amphibians held in zoos, aquaria, and aquaculture facilities. Diet. It apparently feeds on keratin, since it is only found on the keratinized tissues of amphibians. Some research suggests that it may also have non-amphibian hosts or live on dead tissues as well. Life History. This fungus has two life stages: an attached spherical zoosporangium that is the reproductive stage, and a motile zoospore that disperses to new locations on the same host or to a new host organism. No resting stage has yet been discovered. The zoospore has a single

20 n FUNGI

Chytrid Frog Fungus

T

he global decline in amphibian species is an alarming trend with many possible causes. Among them are habitat destruction, climate change, air pollution, increased UV radiation, chemical contamination of water, and the introduction of nonnative competitors and predators. The chytrid frog fungus may be a major new player. Or it may have been there all along and only now reaches fatal levels of infection when a frog or toad population is already severely stressed by other environmental factors.

flagellum with which it moves through water. It attaches to the keratinized outer layers of skin of its host, absorbs its tail, and burrows below the surface. In four days, it will mature into a zoosporangium that has root-like rhizoids that both secrete enzymes to break down keratin and absorb the digested organic products. The zoosporangium forms a single discharge tube that protrudes out of the host’s skin and through which each zoosporangium will release as many as 300 zoospores to start the cycle again. Reproduction is asexual or clonal; like many other chytrid fungi, Batrachochytrium dendrobatidis seems to lack a sexual stage. Impacts. Chytrid frog fungus has been implicated as one of several causes of declining amphibian populations around the world. In the United States, regular low-level infections without deleterious effects seem to have occurred since at least the 1960s. Yet particularly in western states, severe chytrid infections have occurred as populations of several frog species have been decreased dramatically. In Arizona, a rapid die-off in 1997 of the lowland leopard frog (Rana yavapaiensis) and its subsequent extirpation at many of its past locations may have been due in part to chytridiomycosis. In the Sierra Nevada, die-offs of the mountain yellowlegged frog (Rana mucosa) correlated with the presence of Batrachochytrium dendrobatidis; but in and around Pinnacles National Monument, California, few dead frogs were encountered during surveys in 2006–2007 even though the fungus was discovered infecting Pacific tree frogs (Pseudacris regilla), western toads (Bufo boreas), California red-legged frogs (Rana aurora draytonii), and foothill yellow-legged frogs (Rana boylii). Some populations of the Oregon spotted frog (Rana pretiosa), a species in decline in the Pacific Northwest, are persisting even though heavily infected with the fungus. On the other hand, dead and dying boreal toads (Bufo boreas boreas) in Rocky Mountain National Park, Colorado, were found to be infected with the chtyrid fungus, a likely cause of their demise. Die-offs linked to chytrid also are reported in Wyoming and Washington. Susceptibility to the disease is highly species specific and perhaps site specific. It may be more virulent at higher elevations with cooler temperatures. Some more tolerant species such as the American bullfrog and some salamanders may act as transmitters of the parasite. It remains to be discovered how chytrid frog fungus kills its host. Various hypotheses exist, including the possibility that respiration through the frogs’ skin may be affected or that the fungus produces a toxin. Recent research showed that the skin of infected frogs was less able to transport sodium and chloride ions and maintain proper balances of sodium and potassium in the blood. Severe electrolyte imbalances lead to heart stoppage. Much is yet unknown about the impacts of chytrid frog fungus and just how great a risk it is to amphibian populations worldwide. Management. Little can be done to eradicate the fungus once it invades a body of water. To prevent the spread of this potentially lethal parasite, care should be taken to disinfect all equipment, footwear, and clothing before entering a stream or pond. Do not move

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amphibians from one source area to another. Never release captive animals into wetlands, ponds, lakes, or streams.

Selected References Daugherty, Matt, and Kim Hung. “Chytrid Fungus, Batrachochytrium dendrobatidis.” Center for Invasive Species Research, University of California, Riverside, 2009. http://cisr.ucr.edu/chytrid_fungus.html. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Batrachochytrium dendrobatidis (Fungus).” ISSG Global Invasive Species Database, 2006. http://www.issg.org/database/species/ecology.asp?fr=1&si=123. Ouellet, M., I. Mikaelian, B. D. Pauli, J. Rodriguez, and D. M. Green. “Historical Evidence of Widespread Chytrid Infection in North American Amphibian Populations.” Conservation Biology 19(5): 1431–40, 2005. Padgett-Flohr, G. E. “General Amphibian Disease Information.” California Center for Amphibian Disease Control, 2002. http://ccadc.us/docs/AmphibianDiseasesPresentation.pdf.

n Dutch Elm Disease Fungi Scientific name: Ophiostoma novo-ulmi and O. ulmi Synonym: Ceratocystis ulmi Class: Sordariomycetes Order: Ophiostomatales Family: Ophiostomataceae Native Range. Uncertain; probably eastern Asia. The disease was first identified and scientifically described in the Netherlands in 1921 and thus became known as Dutch elm disease. Distribution in the United States. The disease occurs throughout the 48 contiguous states except for the desert regions of the American Southwest. Description. Dutch elm disease is caused by one of two closely related fungi. O. ulmi is becoming less prevalent as it becomes replaced by the more aggressive O. novo-ulmi, believed responsible for most elm mortality from the 1950s through the 1970s. The fungi grow inside the xylem of living trees, where white fruiting bodies may be visible if the xylem is exposed in cross-sectioning; they may be positively identified only in a laboratory. Outward symptoms of this wilting disease of elm trees develop quickly, usually within a month, and are obvious. Leaves on a branch of an apparently healthy tree yellow and wilt, a process known as “flagging.” This is caused by the clogging of xylem tubes by the growing fungi and prevention of water transport; flagging usually becomes evident in late spring, when the tree’s leaves have reached full size. They will eventually turn brown and drop prematurely. Wilting proceeds from the tips of branches downward through the crown, unless the fungus has entered the tree from its roots. In that case, the signs of infection appear first in the lower crown and quickly envelope the entire crown. Often it takes only one year for the whole tree to be affected; but sometimes it takes two or more years. Internal symptoms are the result of dead xylem tissue, revealed by a brown streaking of infected sapwood. These streaks run with the grain and are evident when the bark is stripped from a branch. In a cross-sectional cut of the branch, the vascular damage appears as a ring of brown spots. Two beetles are the vectors for Dutch elm disease, and management often targets these species in order to slow the spread of the fungi. The native elm bark beetle (Hylurgopinus rufipes) is a brownish-black coleopteran sparsely covered with stiff yellow hairs and about

22 n FUNGI 0.08–0.12 in. (2–3.5 mm) long. Its wing cases (elytra) are deeply pitted. The larvae are small, white grubs that produce distinctive galleries beneath the bark of elms. Egg-laying galleries of adults run across the grain, while the smaller tunnels made by larvae come off the main gallery parallel to the grain. H. rufipes burrows into the bark on branches and trunks of elm trees, so the infections it introduces start in major branches. The second vector is an introduced insect, the smaller European elm bark beetle (Scolytus multistriatus). This beetle is slightly larger than the native elm bark beetle and reddish brown. A prominent spine extends from the underside of its concave abdomen. It constructs galleries in the opposite manner of the native elm bark beetle: the egg-laying gallery runs along the grain of the wood, while the larval galleries are cut perpendicular to it across the grain. Since the Top: Eastern Asia is the likely place of origin for the fungi that cause smaller European elm bark beeDutch elm disease. Bottom: The distribution of Ophiostoma novo-ulmi, tle feeds in the crotches of small the chief fungus implicated in Dutch elm disease today. (Adapted from twigs, infections transmitted by “Pest Distribution Map: Dutch Elm Disease, Ophiostoma novo-ulmi.” it occur first in twigs. Alien Forest Pest Explorer, USDA Forest Service, Northern Research Related or Similar Diseases. Station http://www.fs.fed.us/ne/morgantown/4557/AFPE). Two other diseases of elms may be mistaken for Dutch elm disease. Elm yellows (elm phloem necrosis) causes all the leaves of the crown to turn yellow, usually between July and September. Leaves do not wilt or turn brown. No streaking occurs in the sapwood, but the inner bark will be discolored and characteristically develops a wintergreen scent. Bacterial leaf scorch, like Dutch elm disease, infects and clogs the xylem; however, this disease results in a slow decline of the tree over many years. The older leaves on a branch are first to show symptoms of stress. In summer and early fall, the margins of the leaves turn brown, with a yellow area appearing between the green tissue and the scorched outer edge of the leaf. No visible changes to sapwood or inner bark occur. Introduction History. Dutch elm disease was first identified in the United States in Ohio in 1931. O. ulmi had been introduced a few years earlier on diseased elm logs imported from

DUTCH ELM DISEASE FUNGI n 23

France to be used as veneers in furniture making. The smaller European elm bark beetle had arrived ahead of it. O. ulmi probably had been introduced to Europe from Asia around 1910. It is believed responsible for the first epidemic of Dutch elm disease that swept across eastern North America as well as Europe. The more aggressive O. novo-ulmi was likely introduced to the southern Great Lakes region in the 1940s or 1950s; it probably has caused most of the widespread loss of elms since then. The disease spread north and south through the eastern United States and reached the West Coast in 1973. It continues to expand its distribution area and kill off urban and wild elms. However, many seedlings and saplings escape infection long enough to reproduce, so elms are not threatened with extinction. The fungi are spread short distances by elm bark beetles. These insects fly only a few hundred feet away from the tree in which they hatched to feed on another elm. Dispersal distance may be 2 miles (3 km) or more to breeding sites. The rate of spread seldom exceeds 4–5 miles (6–8 km) a year. When trees grow close together (within 25–50 ft. [7.5–15 m] of each other) in pure stands, the usual pattern along city streets, spores from the fungi can be transferred from tree to tree via the roots. Where roots from neighboring trees cross each other, they fuse to create a root graft and allow the passage of the Dutch elm disease pathogen. The spores will carried up the new host tree with the sap in the xylem. Habitat. Urban forests, natural forests, and landscape trees along streets and in yards. O. novo-ulmi and O. ulmi infect only elms (Ulmus spp.). American elm (U. americana) is highly susceptible to the fungus, while other native elm species show a range of resistance; but none is immune to Dutch elm disease. Diet. The fungi that cause Dutch elm disease are both parasites feeding on living tissue of elm trees and saprotrophs living off dead elm tissues. They produce enzymes that digest plant cell walls and perhaps toxins that kill the parenchyma cells of xylem. It is the death of xylem parenchyma that causes the diagnostic discoloration of the sapwood. Life History. Dutch elm disease fungi are introduced into an elm tree when elm bark beetles contaminated with spores bore into the bark to feed or to create egg-laying tunnels. The spores become dislodged and germinate in the galleries to produce thread-like cells, the hyphae, that penetrate into the xylem, where they grow and form the fruiting bodies of the fungus. The fruiting bodies produce millions of white oval spores. These move through the xylem, where they reproduce asexually by budding and spread the disease through the tree. In dying and recently dead trees, a different type of asexual fruiting structure is produced asexually in the bark and in the galleries just beneath the bark: Round, sticky white spores are attached to the top of dark stalks less than 0.1 in. (1–2 mm) tall. The spores adhere to adult beetles and are carried to new elms, when the beetles exit the tree. Sexually produced spores also occur. These accumulate in sticky droplets that can also attach to elm bark beetles to be carried to new host trees. Newly emerged adult beetles first feed on healthy elms. Later, they move to sick or dead elms to breed. Beetles usually have two broods a year, the second of which overwinters and emerges in early summer. The second brood is responsible for the majority of new infections. Impacts. Dutch elm disease has destroyed many millions of elm trees in the United States. The stately, vase-shaped American elm once lined the streets of towns and cities in the eastern part of the country, their arching canopies providing welcome summer shade. The elm was favored as a landscape and urban forest tree because it was beautiful, long-lived, and tolerant of poor air quality and compacted soils. The urban landscape is totally altered with the demise of these trees. The American elm was most susceptible to the disease, but other species, including those in natural forests, are also vulnerable to varying degrees.

24 n FUNGI

A. Smaller European elm beetle, the primary vector for this pathogen. (Gerald J. Lenhard, Louisiana State Univeristy, Bugwood.org.) B. Fruiting bodies of the Dutch elm disease fungus. (William Jacobi, Colorado State University, Bugwood.org.) C. American elms lined many city streets in days past. The vase-like structure of this native species was one of its desirable characteristics. (Joseph O’Brien, USDA Forest Service, Bugwood.org.) D. Galleries made by the smaller European elm bark beetle. (John A. Williams, USDA Forest Service, Bugwood.org.)

Trees are more resistant under drought conditions, and slower-growing individuals are less susceptible than vigorously growing ones. Management. Reducing losses of urban trees from Dutch elm disease requires a community-wide campaign to remove and destroy diseased branches and trees. Root grafts also must be destroyed. Application of systemic chemicals can prevent and treat infections in individual specimen trees, but must be repeated every 2–3 years. Insecticides may control beetle populations, but they must be synchronized with the beetles’ life cycles and can be expensive, and there are potential hazards in handling these products. American elms continue to be planted because of their desirable properties. If arborists avoid large plantings of the same species and space elms well apart from other elms, infection rates and tree losses may be reduced significantly.

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The best long-term solution is the breeding of resistant strains of the elm. Hybridization between American elms and Asian species resistant to or tolerant of the fungus provided resistance but failed to produce the elegant structure of the American tree. Scientists with the Agricultural Research Service and the U.S. National Arboretum discovered and nurtured some old surviving American elms with the necessary resistance and through careful breeding produced varieties that preserved the tall vase shape of the original species; some are now available commercially. They include such cultivars as American Liberty, Princeton, Independence, Valley Forge, New Harmony, and, most recently, Jefferson elms.

Selected References D’Arcy, C. J. “Dutch Elm Disease.” The Plant Health Instructor. American Phytopathological Society, 2000. Revised, 2005. http://www.apsnet.org/edcenter/intropp/lessons/fungi/ascomycetes/Pages/ DutchElm.aspx. doi:10.1094/PHI-I-2000-0721-02. “Fact Sheet: Dutch Elm Disease (Ophiostoma novo-ulmi).” Cornell University, Plant Disease Diagnostic Clinic, 2009. http://plantclinic.cornell.edu/FactSheets/dutchelmdisease/DED.htm. Haugen, Linda. “How to Identify and Manage Dutch Elm Disease.” Northeastern Area State and Private Forestry, USDA Forest Service, n.d. http://www.na.fs.fed.us/spfo/pubs/howtos/ht_ded/ht_ded.htm. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Ophiostoma ulmi sensu lato (fungus).” ISSG Global Invasive Species Database, 2010. http:// www.issg.org/database/species/ecology.asp?fr=1&si=130.

n Sudden Oak Death Also known as: Ramorum blight, SOD Scientific name: Phytophthora ramorum Class: Oomycetes Order: Pythiales Family: Pythiaceae Native Range. Unknown. Two mating types exist, A1 in Europe and A2 in North America. It is presumed that they have a common ancestor, perhaps from Asia. On both continents, the pathogen acts like a new or emerging disease, supporting the idea that it originated somewhere else. (Ramorum blight was first recorded in Europe, on ornamental rhododendrons in Germany in 1993.) Distribution in the United States. Sudden oak death occurs in 14 counties of coastal California stretching 300 mi. (480 km) from Monterey County north to Humboldt County. It is also in neighboring Curry County in southwestern Oregon. Description. The fungus is best described according to the symptoms shown on host plants, which manifest themselves in two groups according to the response to the parasite: bark canker hosts and foliar hosts. Tanoaks (Lithocarpus densiflorus) fall into both categories. On the first group, which includes coast live oak (Quercus agrifolia), California black oak (Q. kelloggii), Shreve oak (Q. parvula var. shrevei), and madrone (Arbutus menziesii), the twigs show the first signs of infection, with discolored patches of dead tissue beneath the bark separated from healthy tissue by a black line or reaction zone. This zone is the advancing front of infection. As the fungus grows in the twig, it spreads into larger branches and causes cankers that lead to branch die-off. With continuing expansion, the infection reaches the stem, where cankers may become more than 6 ft. (2 m) long and girdle the cambium, quickly killing the tree. Characteristically, a red or black sap-like fluid oozes from the canker, staining the bark and

26 n FUNGI killing any lichen or mosses growing on the trunk. The canker attracts western oak bark beetles (Pseudopityphthorus pubipennis) and ambrosia beetles (Monarthtum dentiger and M. scutellare) in abnormally large numbers. The abundance of such beetles is one of the distinct signs of sudden oak death. The dead wood of the canker hosts a saprophytic fungus, Hypoxylon thouarsianum; its fruiting bodies are flattened khaki-green domes that turn black with age and are another indication of infection by sudden oak disease. On small tanoaks, which are both bark canker hosts and foliar hosts, the first signs of the disease are wilting of the branch tips. When the branch dies, the response of the tree is to resprout with multiple new shoots. Tanoaks often display several cankers at different heights above the ground. As with all bark canker hosts, within a few weeks of girdling of the trunk, the crown suddenly browns. Death of evergreen trees such as live oaks may take one or Top: The place of origin of the fungus responsible for sudden oak death two years after infection, with the remains a mystery, although somewhere in Asia is likely. Bottom: Areas brown leaves remaining on the known to be affected by Phytophthora ramorum in 2009. (Adapted from tree during that period. One does map by M. Kelly, University of California, Berkeley. http://www.sudden not find single isolated trees oakdeath.org.) infected by the disease; instead, many trees in close proximity will be killed. Another field observation has been that oak and tanoak trees with bark cankers are always growing near infected bay laurels, which are foliar hosts. Foliar hosts such as coastal redwood (Sequoia sempervirens), Douglas fir (Pseudotsuga menziesii), bay laurel (Umbellularia californica), rhododendrons, and huckleberries are not killed by the fungus; and their infections are often referred to as ramorum blight. The main symptoms of the disease are brown or black spots on green leaves, browning leaves, and sometimes twig dieback. Despite these several signs, sudden oak death cannot be reliably determined in the field, but requires sophisticated laboratory analyses. Related or Similar Species. The symptoms of several ailments may resemble those of sudden oak death including canker rots, leaf scorch, freeze damage, and herbicide damage.

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In the eastern United States, where sudden oak death is not as yet present outside the occasional infections in nurseries, oak wilt presents without cankers or bleeding bark; it is caused by a different fungus, Ceratocystis fagacearum. Oak decline, another disease of eastern oaks, kills many trees, but slowly. It is believed to be brought on by the interactions of multiple stresses such as drought, infections of root fungi such as Armillaria mellea, and infestations of inner bark borers such as two-lined chestnut borer (Agrilus bilineatus) and red oak borer (Enaphalodes rufulus). The red oak borer by itself causes dark, wet stains, but stains on the inner bark show no black zones and are accompanied by beetle burrows filled with fine frass. All other Phytophthora species in temperate areas infect roots and root crowns and spread as soilborne or waterborne spores. Introduction History. The sudden death of large swaths of tanoaks was initially reported in 1995 in Marin and Santa Cruz counties, California. The cause was not identified until 2000, when University of California scientists determined it was as a previously unknown species of the fungus Phytophthora. Later that same year, a researcher in the United Kingdom determined that it was the same fungus that had been affecting rhododendrons in Germany and the Netherlands since 1993. On both continents, the origins of the infections are unknown. In 2001, P. ramorum was discovered on ornamental rhododendrons in a Santa Cruz nursery, and Oregon reported a 40-acre outbreak in Curry County. By 2002, the presence of the fungus was confirmed in natural forests in 10 counties in California. Today, it occurs in 14. In subsequent years, P. ramorum was detected in other nurseries in California and Oregon, and many other states established outright bans on the import of plants from California, or temporary quarantines, inspection, and treatment of imported nursery stock. A major scare occurred in 2004 when infected plants from the huge Monrovia nursery showed up in Colorado, Georgia, Louisiana, Maryland, North Carolina, Texas, and Virginia, as well as Canada. P. ramorum continues to turn up in nurseries across the country. (It has also spread across Europe.) Habitat. The disease is most prevalent in the mild, moist habitats exemplified by the fogswept coasts of California. Temperatures of 64–68°F (18–20°C) and humidity close to 100 percent increase the chances of infection. The fungus that causes sudden oak death is common in the understory of coastal redwood forests on tanoak, in Douglas fir–tanoak forests with understories of huckleberry or other Vaccinium species, and in coastal broadleaf forests on coast live oak, California black oak, Shreve oak, madrone, and bay laurel among at least 100 species known to be susceptible to bark canker or—much more frequently—leaf infections. It lives primarily in the phloem tissues of trees, shrubs, and perennial herbs in natural forests, parklands, and residential areas. Life History. This fungus shows little genetic variability throughout its range in the United States, where it exists as a clone that reproduces only asexually. (Both mating types, A1 and A2, are needed for sexual reproduction.) The fungus forms sporangia, the sacs that produce zoospores, mostly during California’s rainy season between December and June. The sporangia break off and may be carried by the wind some 15 ft. (5 m) away from the original infection site. Sporangia apparently form only in infected leaves, and not on the bark of oaks or tanoak. Zoospores are released when the sporangia land on a new host; they are motile and can swim in water or a water film on the leaves and bark. The cankers on susceptible oaks are usually either close to the soil line, suggesting that rain splash may be a means of dispersal; or adjacent to the leaves of infected bay laurels, suggesting airborne dispersal. No wound in the bark appears necessary to allow infection of those plants that are bark canker hosts, nor can they reinfect themselves since the sporangia develop on fungi infecting leaves.

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A. Canker with zone lines caused by infection by Phytophthora ramorum. B. Canker bleeding. C. Oaks defoliated as a consequence of sudden oak death. (Joseph O’Brien, USDA Forest Service, Bugwood.org.)

Spores can be found in streams all year, so sporulation must occur during the dry season. P. ramorum also forms larger, thick-walled resting spores (chlamydospores) that survive through unfavorable environmental conditions. Much remains to be learned about the life history of P. ramorum, but in some other Phytophthora fungi, the resting spores can remain dormant up to six years. Impacts. In infested areas, high mortality is experienced by tanoaks; and major losses are incurred by coast live oak, Shreve oak, and California black oak. These trees may be dominants in the canopies of the forests in which they occur and many times make up pure stands. When these trees die, the forest floor is no longer shaded, and soils become less permeable to water, changing hydrologic conditions. Gone too are food (acorns) and shelter for wildlife. The dead trees and litter increase the fuel available for wildfires and may change the

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fire regime. Possible changes in species composition in affected forests are yet to be determined. Foliar hosts, although not killed, serve as reservoirs for the disease and are necessary components in the spread of the fungus. This is particularly a problem in ornamental rhododendrons and camellias in California’s nursery trade, which sells plants to other states and countries, and also for companies exporting Christmas trees and redwood mulch. The economic toll of import bans, quarantines, and inspections could be significant. Experiments have shown that northern red oak (Quercus rubra), northern pin oak (Q. palustris), and mountain laurel (Kalmia latifolia) are highly susceptible to sudden oak disease. Many Midwestern and southern forests would be threatened were the fungus to become established in them. Most vulnerable may be forests in the Ozark-Ouachita highlands, live oak stands in Florida, and pin oak sand flats in the Great Lakes area. Management. No way exists to control the disease in the wild. The main management strategy is to prevent its spread via the nursery trade. Since the resting spores survive in soil and leaf litter, it is also important to clean the tires of vehicles and boots of hikers that have been in affected areas and to prohibit the transport of plant debris, including bark, wood, and mulch, from infected areas. In nurseries and individual landscape plants, the infected plant is either treated with a special fungicide or cut down and burned.

Selected References Alexander, J. M., and S. V. Swain, Pest Notes: Sudden Oak Death UC ANR Publication 74151, UC Statewide IPM Program, University of California, Davis, Ca, 2010. http://www.ipm.ucdavis.edu/ PMG/PESTNOTES/pn74151.html. Garbelotto, Matteo. “Sudden Oak Death: A Tale of Two Continents.” Outlooks on Pest Management, 85–89. Research Information Ltd., 2004. http://www.ufei.org/ForesTree/files/collected/Pesticide Outlook.pdf. doi:10.1564/15apl12. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Phytophthora ramorum (fungus).” ISSG Global Invasive Species Database, 2008. http:// www.issg.org/database/species/ecology.asp?si=563&fr=1&sts=sss. O’Brien, Joseph G., Manfred E. Mielke, Steve Oak, and Bruce Moltzan. “Sudden Oak Death” Pest Alert. U.S. Department of Agriculture, Forest Service, State and Private Forestry, Northeastern Area, 2002. http://na.fs.fed.us/spfo/pubs/pest_al/sodeast/sodeast.htm.

n White Pine Blister Rust Scientific name: Cronartium ribicola Division: Basidiomycota Class: Teliomycetes Order: Uredinales Family: Cronartiaceae Native Range. Asia. The natural range of this fungus is unknown but presumed to be Asia, since the disease was unknown in Europe prior to the introduction of eastern white pine (Pinus strobus) from North America in the 1600s. White pine blister rust was first discovered in Europe in the Baltic provinces of Imperial Russia in 1854. From there, it spread westward across Europe. It is supposed that the rust infected native pines in Asia without significant symptoms but when a naı¨ve nonnative species became widely planted, it found a new host and gained virulence.

30 n FUNGI Distribution in the United States. This parasite occurs throughout the range of white (five-needled) pines in the eastern United States, the Great Lakes area, and the mountains of the northwest. It can be found in at least 33 states and continues to expand its range in the Southwest and in southern California. Description. The white pine blister rust fungus requires two hosts, white pines and gooseberries or currants (Ribes spp.; but see below under Habitat) to complete its life cycle; the most visible signs of its presence appear on the pines. Early symptoms of infection occur in late summer or fall as small yellow spots on live pine needles. The fungus spreads down the needle into the vascular system of the twig and, during the next growing season, produces a slight swelling and yellowing of the bark as a diamond-shaped canker forms on the branch. Within a year or two of infection, yellow blisters (aecia) up Top: The place of origin of white pine blister rust is unknown but to 0.25 in. (3 mm) wide erupt presumed to be in the pine forests of Asia. Bottom: White pine blister through the bark in early rust affects both western and eastern pines in the lower 48 states. spring. When the blisters rup(Adapted from map by the Global Invasive Species Team [GIST], the ture, they release vast quantities Nature Conservancy. http://www.invasive.org/gist/photos/crori03.gif.) of yellow-orange spores (aeciospores) and then dry up, leaving a rough patch of bark on the branch. In late spring and early summer, another form of blister (pycnia) appears on the canker. It oozes a sticky yellow-orange fluid that contains pycniospores. Both the blisters and the fluid harden and blacken, and remain on the tree for several weeks. The blisters form again in following years around the margin of the canker, creating a distinctive orange perimeter and expanding the canker until the stem is invaded and girdled and the tree above the canker killed. Rust-infected bark is high in sugar content and attracts rodents; their gnawing at the bark produces copious amounts of pitch (resin) that run down the tree trunk and is another sign of rust infection. The progression of the disease is visible from a distance: chloritic (yellowed) needles, stunted or dead branches (flagging), and eventually dead crowns or dead trees. On gooseberries and currants, the symptoms of rust infection are less obvious. The lower surfaces

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of leaves lose their green color and within a few days become covered with minute orange fruiting bodies (uredinia); these tiny bumps produce yellow-orange spores. In late summer, a different type of fruiting body (telium) covers the underside of the leaves with short yellow-brown hair-like structures. Related or Similar Species. This fungus is the only stem rust of white pines in North America, and it affects only members of the white pine group. Similar symptoms may appear on lodgepole (Pinus contorta) and ponderosa (P. ponderosa) pines, but these are caused by the western gall rust (Endocronartium harknessii). Pine bark adelgids (Pineus strobi), an aphid-like insect introduced from Europe, cover themselves in white, woolly, and waxy secretions; heavy infestations could be mistaken for the pitch-dripping cankers on white pines infected with white pine blister rust. So could Armillaria root rot disease, caused by the fungus Armillaria mellea. When the lower trunks of conifers host this fungus, large amounts of resin are exuded. Introduction History. White pine blister rust first entered the eastern United States on eastern white pine seedlings imported from Germany sometime between 1898 and 1908. The U.S. Forest Service had sent seeds to France and Germany, because American nurseries could not meet the demand when replanting cutovers became the vogue, and then encouraged the planting of millions of imported seedlings across the northeastern states from New England to Minnesota. The blister rust invaded the northwestern United States after having been introduced accidentally in 1910 to Vancouver, British Columbia, Canada, on eastern white pine seedlings from France; however, it was not diagnosed until 1921. During this time period, Americans were beginning to understand that they could no longer cut down forests and move ever westward, but had to practice forest management and make efforts to reforest cutover areas. Europeans had faced these problems much earlier and become accomplished nurserymen, producing seedlings of American white pine as well as European species. Europe thus became a valuable source of seedlings for American foresters. The first outbreak of the disease occurred in 1906 in Geneva, New York, where it was discovered on currants. In 1909, it was found at several eastern locations on eastern white pine seedlings from European nurseries and, by 1915, on native seedlings. By 1922, some areas of New Hampshire saw 50 percent of white pines infected; the rust quickly spread through the forests of the Appalachians and into the Great Lakes region, infecting most major pine regions by 1950. In the west, the blister rust had spread east in western white pine as far as Idaho as early as 1923, and south to Oregon—infecting sugar pine—by 1929. The disease was observed in the northern Sierra Nevada in 1941 and had reached the southern Sierra by 1961. In 1970, it was discovered on southwestern white pine in New Mexico and limber pine in southern Wyoming. It showed up in northern Colorado on limber pine in 1998. The most recently documented range expansion is into central Colorado in 2003, where for the first time it was observed on Rocky Mountain bristlecone pine. It continues to spread through the Great Basin, the southern Rocky Mountains, and the Southwest. Habitat. White pine blister rust infects pine trees that have five needles per bunch. It attacks trees in natural forests as well as those grown in plantations or as ornamentals. Cool, moist weather in summer and early fall is necessary for the infection of the pine host, so it tends to be restricted to more northerly latitudes or high elevations. In the eastern United States and the Great Lakes area, eastern white pine (Pinus strobus) is the sole host. In western states, western white pine (P. monticola), sugar pine (P. lambertiana), whitebark pine (P. albicaulis), limber pine (P. flexilis), and southwestern white pine (P. strobiformis) are hosts. In 2002, the rust was detected on Rocky Mountain bristlecone pine (P. aristata) for the first time.

32 n FUNGI All currants and gooseberries, both wild species and cultivars, are susceptible to some degree to infection as the alternate hosts required by the rust. Most susceptible is the domesticated European black currant (Ribes nigrum). Some red-currant varieties are highly resistant, perhaps immune to the disease. Recently, two western members of the broomrape family (Orobanchaceae), sickletop lousewort (Pedicularis racemosa) and giant red Indian paintbrush (Castilleja miniata), have also been found to serve as alternate hosts. Life History. The white pine blister rust has what is known as a macrocyclic, heteroecious life cycle. It is extremely complex and involves five spore types and requires two alternate host species. Germ tubes from basidiospores released from the life stage of the rust

A. Earlier stage of infection with oozing blisters. (John W. Schwandt, USDA Forest Service, Bugwood.org.) B. Fruiting bodies of Cronartium ribicola. (USDA Forest Service Archive, USDA Forest Service, Bugwood.org.) C. Well-developed canker on eastern white pine. (Minnesota Department of Natural Resources Archive, Minnesota Department of Natural Resources, Bugwood.org.) D. Uredinia on underside of currant leaf. (Petr Kapitola, State Phytosanitary Administration, Bugwood.org.) E. Dead crowns are among the more conspicuous symptoms of white pine blister rust. (Joseph O’Brien, USDA Forest Service, Bugwood.org.)

WHITE PINE BLISTER RUST n 33

that lives on a member of the genus Ribes enter the stomata (pores through which a leaf exchanges gases with the atmosphere) of a white pine needle. They grow down the length of the needle and establish mycelia in the vascular tissue of the twig to which the needle is attached, parasitizing living cells. Blister rust cankers expand with time to the branch and eventually the main stem (trunk) of the tree. A year or two after infection, pycnia develop at the margin of the canker and produce pycniospores. Pycniospores result in mycelia that produce aecia (a cuplike fruiting body) the next year. Aecia break through the bark, covered by white membranes that create blisters. When the membrane ruptures, quantities of orange aeciospores are released. Pines cannot directly infect other pines; the aeciospores must find an alternate host for the next phase of the rust’s life cycle. The wind can carry them over hundreds of miles, and if conditions are optimal, they will survive for several months until they land on and infect a wild or cultivated currant or gooseberry. Mycelia grow in the Ribes leaf, and within a few weeks of the initial infection, the rust produces tiny pustules (uredinia) on the underside of the Ribes leaf; from these fruiting bodies urediospores are released, spreading the rust to other currants or gooseberries nearby. These spores cannot infect pines. The rust has entered what is known as the repeating stage, when reinfection of the same alternate host species occurs over and over. In late summer, after two weeks of cool, moist weather, hairlike telial fruiting bodies emerge from the underside of the Ribes leaf. These release basidiospores that are wind-dispersed a distance usually less than 1,000 ft. (300 m) and that, if successful, land on a white pine. Their germ tubes enter the needles’ stomata to begin the cycle again. The rust overwinters in the pine; it dies in Ribes or outside a living host. The disease progresses from needle to twig, to branch, to the trunk of the tree as the mycelia grow through the vascular system and absorb water and nutrients from the living cells. Cells of the host pine die as they become undernourished or the flow of nutrients is blocked. Once a branch or trunk is girdled by the canker, the tissues beyond the infection point are cut off from water and nutrients, and they die. It may take 15 years for a tree to be killed. Ribes shrubs, on the other hand, are not killed by the fungus, but severe infections may lead to defoliation. Impacts. In the early twentieth century, when the white pine blister rust was introduced, American commercial forestry revolved around the harvest of white pine. When the eastern white pine was logged out of New England and other northeastern states, the industry had shifted westward to the Great Lakes region. By 1900 it was beginning to cut western white pine and sugar pine from the northern Rocky Mountains to the Cascades and Pacific Northwest. Eastern white pine was being replanted in the eastern United States, often with inexpensive seedlings from France and Germany. The rust is especially lethal to young trees of sapling and pole size. Efforts to protect these valuable timberlands began almost immediately and influenced the impacts of the fungus on native forests. White pine blister rust has caused more damage and had more money spent on its control than any other disease of conifers in the United States. Thousands of stands became unsuited for lumber production or were lost entirely. The initial invasion in the Northeast resulted in high rates of infection and mortality but also selected for existing resistance in eastern white pine. In New Hampshire in the first half of the twentieth century, for example, disease incidence ranged from 20 to 80 percent in sampled stands. By the end of the century, the rate of infection was 7 percent or less. The maturing of surviving white pine probably affects the rate, since young trees are more susceptible to infection. Today, the rust is widespread but not frequent, and not a major concern. Eradication of wild and cultivated Ribes as a primary management strategy (see under Management), probably shifted the relative abundance of wild currants in natural forests, although increased forest cover also reduces the abundance of these sun-loving shrubs.

34 n FUNGI Sugar pine and western white pine are valuable timber trees that have been severely affected by the rust in the western United States. The harvest of western white pines accelerated when white pine blister rust was discovered in the Pacific Northwest. White pines were selectively removed in salvage operations, leaving shade-tolerant conifers such as western hemlock (Tsuga heterophylla) and grand fir (Abies grandis) to become dominants in the forest canopy. Regrowth of white pines was impeded not only by the rust, but by fire suppression policies, which eliminated the burns pines often require for germination. High-elevation white pines in the west, especially whitebark pine and limber pine, provide food and cover for a variety of wildlife and plant species. Several produce large seeds that are important elements of the diets of Clark’s Nutcrackers (Nucifraga columbiana), and other birds, as well as grizzly bear (Ursus arctos) and black bear (U. americanus). Squirrels could be negatively affected if these forests decline, as would their predators. The demise of white pines that occupy steep, dry slopes may turn these sites into treeless areas. The loss of trees will change slope stability and hydrologic patterns and also alter fire and other disturbance regimes and forest succession. These trees also have scenic value and contribute to the attractiveness of several national parks as well as the tourist economy of the region. Stands of dead whitebark pine occur in Crater Lake, North Cascades, and Glacier national parks. Some scientists believe that all whitebark pines in Glacier National Park may be dead by 2015. White pine blister rust is an important disease in terms of the history of forest pathology and became one of the most famous tree diseases in the world. Since it struck valuable timber trees, and since it was discovered early on that something could be done to control its spread (unlike the Chestnut blight fungus), it fostered new pest management agencies and techniques including regulations against importing exotic species and establishment of quarantine zones. The devastation wrought by white pine blister rust and chestnut blight in the first decade of the twentieth century led to the passage of the Plant Quarantine Act by the U.S. Congress in 1912. It was the first law aimed at preventing the introduction of foreign pests into the United States. Management. The earliest strategies to control the spread of white pine blister rust focused on the eradication of Ribes as an alternate host. This was somewhat successful in the eastern United States, where cultivated currants and gooseberries were the chief hosts, since only a few wild species in the genus occurred there. Planting, possessing, or importing Ribes is still forbidden in some counties that remain in quarantine districts, although such laws are rarely enforced. In the West, where many native species occur in the wild, the strategy was totally impractical and soon abandoned. Site management for new plantings grew in importance and included the hazard rating of areas according to conditions that support basidiospore production. High-hazard sites usually are low areas where moist, cold air settles at night. Small openings in a forest also have high potential for basidiospore production, because dew often persists on pine seedlings in such areas. A thin overstory can be maintained to prevent dew formation and still allow sufficient sunlight to reach pine seedlings. Pruning the lower branches of saplings up to 10 ft. (3 m) above the ground keeps fungal infections from extending into the trunks of young trees, and it has the added commercial advantage of providing knot-free timber. In natural forests, the greatest hope lies in the development of resistant trees. Natural selection for such trees seems to have occurred in the Northeast, where the rust entered after mature trees had been removed and many young trees were planted. Breeding programs based on some naturally resistant individuals are progressing throughout the country. Seedlings of resistant western white pine are available to the public; for other species, such as eastern white pine and sugar pine, programs are still in experimental stages.

WHITE PINE BLISTER RUST n 35

Selected References Cox, Sam. “White Pine Blister Rust: The Story of White Pine, American Revolution, Lumberjacks, and Grizzly Bears.” 2003. http://landscapeimagery.com/wphistory.html. Geils, B. W. “Impacts of White Pine Blister Rust.” In Proceedings, U.S. Department of Agriculture interagency research forum on gypsy moth and other invasive species 2001, ed. S. L. C. Fosbroke and K. W. Gottschalk. January 16–19, 2001, Annapolis, MD. Gen Tech. Report NE-285. Newton Square, PA: U.S. Department of Agriculture, Forest Service, Northeastern Research Station: 61–64, 2001. Available online at http://www.rmrs.nau.edu/rust/Geils2001/text.html. Laskowski, Michele. “White Pine Blister Rust.” High Elevation White Pines. http://www.fs.fed.us/rm/ highelevationwhitepines/Threats/blister-rust-threat.htm. Maloy, O. C. “White Pine Blister Rust.” In The Plant Health Instructor. American Phytopathological Society, 2003. Updated, 2008. http://www.apsnet.org/education/LessonsPlantPath/WhitePine/ symptom.htm. doi:10.1094/PHI-I-2003-0908-01. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Cronartium ribicola (Fungus).” ISSG Global Invasive Species Database, 2005. http:// www.issg.org/database/species/ecology.asp?si=550&fr=1&sts=sss. Nicholls, Thomas H., and Robert L. Anderson. “How to Identify White Pine Blister Rust and Remove Cankers.” North Central Research Station, Forest Service, U.S. Department of Agriculture, 1977. http://www.na.fs.fed.us/spfo/pubs/howtos/ht_wpblister/toc.htm. “White Pine Blister Rust Factsheet.” Plant Disease Diagnostic Clinic, Cornell University, 2005. http:// plantclinic.cornell.edu/FactSheets/wpineblister/wpineblister.htm. Worrall, James J. “White Pine Blister Rust.” Forestpathology.com, 2009. http://www.forestpathology .org/dis_wpbr.html.

n Invertebrates n Bryozoan n Lacy Crust Bryozoan Also known as: Sea moss, white lace bryozoan Scientific name: Membranipora membranacea Family: Membraniporidae Native Range. Lacy crust bryozoans are native to the temperate, coastal waters of Europe, where they are found in the northeast Atlantic Ocean, Baltic Sea, and Mediterranean Sea. They also occur naturally along the Pacific Coast of North America from Alaska to Baja California. Distribution in the United States. The lacy crust bryozoan is a nonnative invasive in the coastal bays of New England; it is established in Connecticut, Maine, Massachusetts, New Hampshire, and Rhode Island. Description. This epiphytic bryozoan forms white, circular colonies that are about 0.04 in. (1 mm) thick and 0.5 in. (1 cm) in diameter. The colonies grow outward, with the oldest member at the center and younger individuals, or zooids, radiating in rows away from it to form lacy or net-like encrustations on seaweeds. Each zooid, about the size of a pin head, is rectangular and box-like and has short knob-like spines at each corner that make the colony feel like sandpaper. The side walls of the zooid are thin and only slightly calcified; the top is transparent, allowing light to reach the seaweed that it encrusts. Related or Similar Species. Native bryozoans of the Northwest Atlantic do not have rectangular zooids. Sea mat or horn wrack (Electra pilosa), the encrusting bryozoan with which lacy crust bryozoans might most easily be confused, has egg-shaped zooids surround by spines (4–12; usually 9); a large central spine protrudes from the zooid, giving E. pilosa a spiny appearance. Colonies of sea mat form snowflake- or star-shaped colonies. Introduction History. This bryozoan first appeared on sugar kelp (Laminaria saccharina) in the Gulf of Maine at the Isles of Shoals in 1987. It likely arrived in a ship’s ballast water or as a fouling organism on the hull of a ship. It spread north and south from its point of introduction and, by 1990, was the dominant epiphyte on kelp off the shores of Maine and New Hampshire. It has since reached Cape Breton, Nova Scotia. Habitat. Lacy crust bryozoan colonies encrust kelps and other macroalgae in the shallow subtidal zone of temperate seas. They are most common on Laminaria kelps. These bryozoans will also attach to other smooth, hard surfaces such as rocks, glass, and floats. They flourish where there is fast-flowing water or a high tidal exchange. Diet. These filter-feeders sieve phytoplankton from seawater with a ring of tentacles called a lophophore. Life History. After the initial zooid becomes attached to a kelp frond, new zooids bud off (asexual reproduction); the colony grows several millimeters a day beginning in late spring. Growth continues throughout the summer, and by fall, large crusts may be apparent as

LACY CRUST BRYOZOAN n 37

several colonies merge together. Unlike many other bryozoans, in which different types of zooids perform different functions for the colony, only one type of zooid occurs in the lacy crust, and it is involved in feeding, reproduction, and defense. Sexual reproduction usually occurs in spring and summer, when zooids produce eggs and release them into the water. The individual animals may be hermaphroditic in that eggs are fertilized before they are shed. The free-floating eggs quickly develop into tiny triangular larvae (cyphonautes) that become part of the plankton. They settle when they contact an algal frond and grow toward its base, the most stable part of the seaweed. Different colonies compete for space and interact both aggressively and cooperatively, and they can communicate with each other by means of electrical signals. Sea slugs (nudibranchs) such as Onchidorus muricata are the primary predators of lacy crust bryozoans. Top: The lacy crust bryozoan is native to the coastal waters of Europe and Impacts. Lacy crust bryo- the Pacific coast of North America. Bottom: The lacy crust bryozoan has zoan colonies weigh down the invaded coastal waters off New England. (Both maps adapted from kelp fronds that they heavily “Membranipora membranacea,” USGS 2009.) encrust and make the fronds especially susceptible to breakage during storms. This has caused a reduction and, in some cases, total loss of kelp beds in the waters off New England. They apparently also exclude native encrusting animals from kelp and other suitable attachment substrates and interfere with the host kelp’s spore production. Kelp beds are important habitat and nursery areas for a variety of marine organisms, including sea urchins, lobsters, and finfish, all of which are therefore threatened by the invasion of this bryozoan. The green or northern sea urchin (Strongylocentrotus droebachiensis) in particular has declined in numbers since the introduction of lacy crust. Where kelp beds have been denuded in the Gulf of Maine, a nonnative green algae called oyster thief or dead man’s fingers (Codium fragile tomentosoides) has invaded and prevented the restoration of kelp beds. Management. There is no effective way to prevent the spread of this organism.

38 n INVERTEBRATES (BRYOZOAN)

A. Colony of lacy crust bryozoans, showing the box-like zooecia. B. Close-up of zooecia with knobby spines clearly visible at each corner. C. Rings of tentacles or lophophores are extended when the zooecia are filtering food particles from sea water. (Dave Cowles: http://rosario.wallawalla.edu/inverts.)

Selected References Cowles, Dave, and Jonathan Cowles, “Membranipora membranacea (Linnaeus, 1767),” 2007. http:// www.wallawalla.edu/academics/departments/biology/rosario/inverts/Bryozoa/ Class_Gymnolaemata/Order_Cheilostomata/Membranipora_membranacea.html. “Lacy Crust Bryozoan.” Project UFO (Unidentified Foreign Organisms), n.d. http://www.projectufo.ca/ drupal/Lacy_Crust_Bryozoan. “Membranipora membranacea (Linnaeus 1767).” Nonindigenous Aquatic Species Program, U.S. Geological Survey, 2009. http://nas3.er.usgs.gov/taxgroup/Bryozoans/. “Membranipora membranacea.” Species Identification Card, Gulf of Maine Research Institute, n.d. http://www.gmri.org/upload/files/VS_Membranipora_membranacea.pdf. Telnack, Jennifer. “Membranipora membranacea: The LacyCrust Bryozoans.” Intertidal Marine Invertebrates of South Puget Sound, n.d. http://www.nwmarinelife.com/htmlswimmers/m _membranipora.html.

CHAIN TUNICATE n 39

n Tunicates n Chain Tunicate Also known as: Chain sea squirt, orange or red sheath tunicate, violet tunicate Scientific name: Botrylloides violaceus Family: Styelidae Native Range. East Asia, from southern Siberia to southern China and Japan. Those in the United States are believed to have come from Japan. Distribution in the United States. Chain tunicates have invaded both coasts of the continental United States. Along the Pacific Coast, they occur in disjunct locations in Prince William Sound and Sitka, Alaska; Puget Sound and Willapa Bay, Washington; Coos Bay, Oregon; and Humboldt Bay, Bodega Harbor, Tomales Bay, San Francisco Bay, Half Moon Bay, Monterey Bay, Elkhorn Slough, Morro Bay, Santa Barbara, Channel Islands Harbor, Port Hueneme, Marina Del Rey, King Harbor, Santa Catalina Island, Alamitos Bay, Huntington Harbor, Mission Bay, and San Diego Bay, California. On the Atlantic Coast, they are established from Maine south to the entrance to the Chesapeake Bay and possibly to Florida. Description. The chain tunicate is a sessile, colonial sea squirt consisting of many individual small animals or zooids arranged in elongated clusters or double-rows and chains called systems. Individual zooids are about 0.1 in. (1–2 mm) long; the largest colonies may be about 1 ft. in diameter (0.3 m) and sometimes develop lobes. All the zooids in a given colony Top: The chain tunicate Botrylloides violaceus comes from waters off East are the same color: red, orange, Asia. Bottom: Chain tunicates are invasive on both coasts of the yellow, purple, or tan. continental United States. (Adapted from Fuller, P., “Botrylloides Each zooid is vase-shaped violaceus.” USGS Nonindigenous Aquatic Species Database, Gainesville, and sits upright on the substrate. FL. http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=2418.)

40 n INVERTEBRATES (TUNICATES) It separately draws water into its body through its own siphon but expels it into a common space from which the waste water leaves the entire colony. The zooids are connected together by a vascular network that ends in small sacs (ampullae) at the edge of the colony. These tiny blobs are pigmented and the same color as the zooids. A clear, firm matrix forms between the systems and surrounds the whole colony. This invertebrate is the only chordate known to be able to regenerate its entire body from pieces of the colony’s vascular network. Related or Similar Species. The golden star tunicate (Botryllus schlosseri) is another invasive colonial tunicate found on both coasts of North America. As its common name suggests, its zooids are arranged in star patterns and not in chains. Colonies display two colors rather than just one. On the Pacific Coast, from Baja California to San Francisco Bay, one can find Botrylloides diegensis, the individual zooids of which are dichromatic; the ring around the oral siphon is a pale or bright white, yellow, or orange and contrasts with the darker color of the body. A recently introduced colonial tunicate in San Diego and Mission bays, Botrylloides perspicuum, is distinguished by a thicker and firmer matrix that forms ridges between systems of zooids. There are also microscopic differences among these tunicates and diagnostic characters in their larvae. The chain tunicate might be mistaken for various red or orange sponges, but it is more rigid than a sponge. Introduction History. The earliest record of the chain tunicate in the United States is from the Pacific Coast, where it was reported in 1973 in San Francisco Bay. It likely arrived as a fouling organism on a ship from Japan, but could have been introduced with Japanese oysters (Crassostrea gigas). It was first reported in Puget Sound in 1997 and in Prince William Sound in 1999. However, the organism may have arrived earlier. Collection was limited prior to the 1970s, and until 1997, the chain tunicate was not recognized as a form distinct from the very similar B. diegensis. It was first reported on the Atlantic Coast in 1981, although again, confusion with B. diegensis may have obscured an earlier arrival in the 1970s. In 1981, it was in Great Bay, New Hampshire, in the Gulf of Maine; by the mid1990s, it was in Penobscot Bay. Early records in the lower Chesapeake Bay date to 2000 and 2001. (In 2004, it had expanded northward and was reported on cultured mussels being grown on Prince Edward Island, Canada, in the Gulf of St. Lawrence.) Dispersal to new areas along the coasts of North America may occur in contaminated oyster shell and spat associated with the oyster industry, as fouling organisms on the hulls of ships, or by rafting on debris. Since the planktonic larval stage is so brief, it is unlikely that it spreads far if at all in ballast water. Habitat. Chain tunicates occur in sheltered areas of the shallow subtidal zone. Adults and juveniles attach to submerged surfaces such as rocks, pilings, ropes, boat hulls, macroalgae, eelgrass (Zostera marina), and the shells of mussels, oysters, and barnacles. They will also grow over encrusting bryozoans and solitary tunicates. Chain tunicates can live in a range of salinities (24–34 ppt) and temperatures (46–77°F [8–25°C]). It reportedly tolerates polluted water. Diet. Adults and juveniles are suspension feeders that filter phytoplankton and bacteria from seawater. Life History. Chain tunicates reproduce both sexually and asexually. The zooid is hermaphroditic and viviparous. It has a brood pouch that extends out from the body wall into the matrix. The egg is ovulated into the brood pouch, where it is fertilized. The embryo develops into a relatively large (0.08–0.12 in. [2–3 mm] long), brightly colored, tadpolelike larva. Gestation is longer than four weeks. Each pouch will hold one egg; each zooid may have one or two pouches.

CHAIN TUNICATE n 41

Upon release from the brood pouch, the larva is freeswimming for a very short time. In just a few hours, metamorphosis takes place, and the juvenile (oozoid) attaches head first to a hard surface. The newly attached oozoid metamorphoses into a zooid and starts to reproduce asexually by budding the next day. A new colony is thus begun. All the zooids of a given generation grow and die synchronously. As the oldest generation disintegrates, it is absorbed into Individual vase-shaped zooids of the chain tunicate are arranged in rows and connected by a vascular system that ends in tiny sacs at the edge of the colony’s vascular system. Impacts. Chain tunicates the colony. (Dann Blackwood, U.S. Geological Survey.) may compete for settling space and food with other native and introduced fouling organisms, but generally its ecological impacts are unknown. It has become a nuisance species in mariculture operations producing mussels in Canada, where it overgrows and smothers the bivalve; so it could become a pest in oyster operations in the Chesapeake Bay or wherever other shellfish are cultured. As it becomes more abundant, it will become a problem, fouling fishing and boating gear and requiring time and expense to remove. Climate change may alter the story. Studies show that chain tunicates settle earlier and grow faster than natives in warming waters. As natives decline in face of winter warming, these tunicates may become dominant. Management. Similar species have followed the typical pattern of a new invader: rapid population growth followed by a period of decline and adjustment of the fouling community without the loss of native species. It appears that the chain tunicate also will not replace natives, and that management or eradication measures are unnecessary and would likely be unsuccessful anyway.

Selected References “Botrylloides violaceus.” Chesapeake Bay Introduced Species Database NEMESIS: National Exotic Marine and Estuarine Species Information System, Smithsonian Environmental Research Center (SERC), 2005, 2009. http://invasions.si.edu/nemesis/CH-INV.jsp?Species_name=Botrylloides +violaceus. Cohen, Andrew N. “Botrylloides violaceus Oka, 1927.” Guide to the Exotic Species of San Francisco Bay. San Francisco Estuary Institute, Oakland, CA, 2005. http://www.exoticsguide.org/species_pages/b _violaceus.html. Pleus, Allen, and Pam Meacham. “Botrylloides violaceus (Chain tunicate),” Invasive Species Fact Sheets, Aquatic Nuisance Species, Washington Department of Fish and Wildlife, n.d. http://wdfw.wa.gov/ fish/ans/identify/html/index.php?species=botrylloides_violaceus. “Tunicate, Botrylloides violaceus.” Non-indigenous Aquatic Species of Concern for Alaska, Fact Sheet 15. Prince William Sound Regional Citizens’ Advisory Council, 2004. http://www.pwsrcac.org/ docs/d0016000.pdf.

42 n INVERTEBRATES (TUNICATES)

n Colonial Tunicate Also known as: Didemnid, colonial ascidian, colonial sea squirt, marine vomit Scientific name: Didemnum vexillum Synonym (in older literature): Didemnum sp., Didemnum sp. A. Family: Didemnidae Native Range. Uncertain; possibly Japan. Distribution in the United States. East Coast, from Maine to New Jersey and offshore on Georges Bank; West Coast, California and Washington. Description. Didemnid colonies take various forms. Where the current is weak, they hang from hard structures in long stringy lobes resembling ropes or beards. This is the usual morphology on pilings, ship hulls, ropes, and the like. Where the current is strong, they grow in dense flat mats with low protruding lobes or tendrils and encrust rock outcrops, pebbles, and cobbles. Colonies are tan, cream-colored, white, or yellow and may attain a diameter of 3 ft. (1 m) or more. Thousands of individual zooids comprise each colony. Each is about 0.1 in. (2.5 mm) long. They are embedded in a clear, firm matrix, the surface of which is dotted with tiny white calcareous balls, each covered with spines. These may not be visible to the naked eye. All zooids in a given colony are the same color. Related or Similar Species. On the Pacific Coast, all three related colonial tunicates (D. carnulentum, D. albidum, and Trididemnum apacum) have spiny balls throughout the matrix and not limited to the surface as in D. vexillum. Their colonies are never lobed, but always flat and encrusting; they are usually white or gray. On the East Coast, the colonial tunicate could be confused with the chain tunicate, Botrylloides violaceus (see Tunicates, Chain Tunicate), but Top: The colonial tunicate Didemnum vexillum may come from the waters the colonial tunicate is never the off Japan. Bottom: D. vexillum has invaded both coasts of the continental red or orange color of chain United States. (Adapted from “Species Didemnum vexillum.” USGS 2010.) tunicates.

COLONIAL TUNICATE n 43

Colonial tunicates could also be mistaken for sponges, but they have a smoother texture than a sponge. Introduction History. The first documented occurrence of the colonial tunicate on the East Coast was in Fort Island Narrows on the Damariscotta River in Maine in 1993. It was likely present but unidentified prior to that time. Reports of a similar organism in Walpole, Maine, date to 1988; and it is suspected that the tunicate was in New England waters by the 1970s. Didemnum vexillum was first collected in Shinnecock Bay, Long Island, New York, in late 2004. The first records on Georges Bank date to 2003 and are the first evidence of invasion of offshore habitats. On the West Coast, D. vexillum was collected from San Francisco Bay in 1993. It was recovered from Elkhorn Slough, Monterey Bay, California, in 1998, but originally misidentified as a native species, D. carnulentum. Since then, it has been collected in Bodega Harbor, Humboldt Bay, Tomales Bay, Morro Bay, and Port San Luis. On the Washington coast, it was first documented on a sunken wooden boat in Puget Sound in March 2004. Colonial tunicates were most likely carried to the coasts of North America as fouling organisms on transoceanic vessels. They also may have arrived as colony fragments in ballast water. On the Pacific Coast, it is possible that they were accidentally introduced with oyster or mussel stock or with equipment delivered to aquaculture facilities. Why this species has suddenly become invasive is not known. However, fragments capable of starting new colonies are easily broken off by bottom-fishing dredges, by divers, and by local boat traffic. These pieces may then drift in currents over long distances to new sites. Habitat. Colonial tunicates are usually associated with man-made structures in the subtidal zone of coastal waters. They have been found on docks, moorings, metal and wooden pilings, ropes and steel chains, discarded automobile tires, and polythene plastic. They also foul shellfish aquaculture gear and ships’ hulls. On the seabed, they encrust hard substrates such as rock outcrops, cobbles, pebbles, and boulders and overgrow sessile benthic organisms such as hydroids, solitary tunicates, sponges, barnacles, mussels, and oysters, as well as seaweeds. They occur in shallow coastal waters and also on the continental shelf to depths of about 200 ft. (65 m). These tunicates tolerate water temperatures ranging between 28° and 75°F (−2°–24°C) and apparently require a salinity greater than 26 ppt. Diet. These filter-feeders siphon seawater into their bodies and consume the phytoplankters and zooplankters, including the larvae of oysters and mussels, held in it. Life History. The colony broods its larvae within its matrix and then releases them into the water column. They are part of the plankton for only a few hours before they attach head down to a firm surface. Larval settlement occurs in spring and fall. The settled larva quickly metamorphoses into a zooid, which becomes the founder of a new colony. The colony expands through budding (asexual reproduction). Young zooids reach sexual maturity in just a few weeks. A new colony can also form via fragmentation when a fragile lobe of the colony breaks off and drifts to a new location, where it either settles to the bottom or becomes entangled in marine structures. Such stray pieces may attach to a new substrate within six hours of arrival and start overgrowing it. Impacts. Colonial tunicates overgrow hard substrates and the native organisms attached to them and thereby threaten to change benthic marine habitats. The high acidity of their tunics may inhibit settling of the larvae of shellfish such as scallops. The overgrowth of gravelly bottoms could reduce habitat in which fish such as Atlantic cod (Gadus morhua) and haddock (Melangrammus aeglefinus) deposit their eggs. The tunicates can smother bivalves,

44 n INVERTEBRATES (TUNICATES)

Colonies of the colonial tunicate Didemnum vexillum take a variety of forms. A. Thousands of individual zooids, each about 0.1 in. long, make up a colony. (Dann Blackwood, U.S. Geological Survey.) B. Stringy lobes occur where currents are weak. Here Didemnum covers metal piling and a mussel shell. (Paul Barter, Cawthron Institute, New Zealand.) C. Stiffer lobes protrude when currents are strong. Here the colonial tunicate has encrusted a mussel shell. (Dann Blackwood, U.S. Geological Survey.) D. Mats overgrow the gravelly bottom of Georges Bank. (Dann Blackwood, U.S. Geological Survey.)

so concern exists for oyster (Crassostrea spp.), bay scallop (Argopecten irradians irradians), sea scallop (Placopecten magellanicus), and mussel fisheries, both natural and cultured. Studies on Georges Bank show an increase in two polychaete species in areas infested with the colonial tunicate, suggesting a change in native species composition on the seafloor. Fouling of aquaculture gear, moorings, ships’ hulls, and so forth requires expensive maintenance procedures and makes this a major nuisance species. Management. Wrapping pilings in plastic may suffocate colonial tunicates, but this is only of local significance as a method of control. Vacuuming colonies from the water has been tried, but it did not succeed in eradicating the species. Prevention or slowing the spread of the animal is difficult because of its fragile tunic and ability to rapidly reproduce asexually. Boaters, divers, fishermen, and aquaculturalists could slow the invasion by keeping equipment clean and not discarding bivalve shells in noninfested waters.

Selected References Cohen, Andrew N. “Didemnum sp. A.” Guide to the Exotic Species of San Francisco Bay. San Francisco Estuary Institute, Oakland, CA, 2005. http://www.exoticsguide.org/species_pages/didemnum .html.

AUSTRALIAN SPOTTED JELLYFISH n 45 Lengyel, Nicole L., Jeremy S. Collie, and Page C. Valentine. “The Invasive Colonial Ascidian Didemnum vexillum on Georges Bank—Ecological Effects and Genetic Identification.” Aquatic Invasions (4): 143–52, 2009. doi:10.3391/ai.2009.4.1.15 http://www.aquaticinvasions.net/2009/AI_2009_4_1 _Lengyel_etal.pdf. Morris, James A., Jr., Mary R. Carman, K. Elaine Hoagland, Emma R. M. Green-Beach, and Richard C. Karney. “Impact of the Invasive Colonial Tunicate Didemnun vexillum on the Recruitment of the Bay Scallop (Argopecten irrradians irradians) and Implications for Recruitment of the Sea Scallop (Placopecten magellanicus) on Georges Bank.” Aquatic Invasions (4): 1: 207–11, 2009. doi:10.3391/ai.2009.4.1.22 http://www.aquaticinvasions.net/2009/AI_2009_4_1_Morris_etal.pdf. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialty Group (ISSG). “Didemnum spp. (Tunicate).” ISSG Global Invasive Species Database, 2007. http:// www.issg.org/database/species/ecology.asp?si=946&fr=1&sts=sss. “Species Didemnum vexillum.” Marine Nuisance Species, USGS National Geologic Studies of Benthic Habitats, Northeastern United States, 2010. http://woodshole.er.usgs.gov/project-pages/stell wagen/didemnum/.

n Cnidarian n Australian Spotted Jellyfish Also known as: Spotted jellyfish, white-spotted jellyfish Scientific name: Phyllorhiza punctata Order: Rhizostomeae Family: Mastigiidae Native Range. Before the 1950s, the Australian spotted jellyfish was only known from the Indo-Pacific region. Its native range is believed to have extended from the south-central coast of eastern Australia northward into Southeast Asia and the Philippines. Distribution in the United States. Populations are becoming established along the Gulf Coast from Galveston Bay, Texas, to Orange Beach, Alabama, east of Mobile Bay. Another permament population occurs on the Atlantic Coast in Indian River Lagoon, Florida. In the summer of 2007, swarms of medusae were sighted off South Carolina, but these may not represent a permanent population. In Hawai’i, populations occur in Pearl and Honolulu harbors and in Kaneohe Bay, O’ahu. Australian spotted jellyfishes are also established in Boqueron Bay, Puerto Rico. Description. This is a large jellyfish with a somewhat flattened semi-globular gelatinous bell or umbrella. In much of its natural and introduced range, it is bluish white or brown due to symbiotic zooxanthellae; however, in the Gulf of Mexico, it is clear or white due to the absence of these photosynthetic algae. Crystalline opaque white inclusions appear as evenly spaced spots. Eight thick, branching oral arms surround the central mouth area; each ends with a large brown bundle of stinging cells. Transparent ribbons of tissue hang from each oral arm. The average bell diameter of an adult is 14 in. (35 cm), but in the Gulf of Mexico, they are much larger than elsewhere, with an average diameter of nearly 18 in. (45 cm). The largest reported was 24.4 in. (62 cm) in diameter. These large specimens can weigh up to 25 lbs. (11 kg). They are only mildly venomous and not dangerous to humans. Related or Similar Species. The native moon jelly (Aurelia aurita) is of similar size but otherwise very different in appearance. Introduction History. Australian spotted jellyfish likely entered the Atlantic Ocean and Caribbean Sea on ships passing through the Panama Canal sometime in the early 1950s, if not earlier. Polyps attached to the hulls of ships and/or young medusae held in ballast water could

46 n INVERTEBRATES (CNIDARIAN) have survived the journey from the Pacific. The first colonies appeared off northeast Brazil in 1995. Populations have been established in Puerto Rico and in other lagoons in the Caribbean since at least the early 1970s. The Australian spotted jellyfish was first documented in the Gulf of Mexico by a single specimen collected in 1993. The natural circulation pattern of ocean currents from the Caribbean into the Gulf of Mexico could have carried them northward to the Gulf Coast of the United States, where small populations such as that in Terrebonne Bay, Louisiana, became established in the mid-1990s. They could also have been introduced as attached polyps on ships and towed structures. The proliferation of oil platforms in the Gulf of Mexico may have improved the habitat for these jellyfish and facilitated establishment of local populations by providing attachment sites for the polyp stage and allowing for natural dispersal northward. Overfishing could Top: The Australian spotted jellyfish was limited to the Indo-Pacific also have released resources preregion prior to the 1950s. Bottom: Australian spotted jellyfish are cur- viously tied up by native species. The spectacular 2000 invarently established along the Gulf Coast of the United States and off O’ahu, HI, and western Puerto Rico. (Adapted from Perry 2010.) sion of thousands of medusae along the Gulf Coast, like the later 2007 one, appeared to have come from the Caribbean though the Yucata´ n Straits into the Gulf of Mexico, although recent genetic studies do not strongly support this scenario and suggest that the Caribbean jellyfishes may be another species altogether. Gulf Coast jellyfish are more similar to those from Australia or the West Coast, suggesting an invasion via transoceanic shipping. Medusae were observed in Galveston Bay in 2006. The Australian spotted jellyfish was first identified on the Atlantic Coast in Indian River Lagoon near Melbourne, Florida, in 2001. The 2007 sightings off the coast of South Carolina represent the first known occurrence of the jellyfish north of Florida. In Hawai’i, the jellyfish entered Pearl Harbor from the Philippines during World War II (1941–1945). It appeared in Kaneohe Bay in 1953–1954. The first reports of Australian

AUSTRALIAN SPOTTED JELLYFISH n 47

spotted jellyfish in coastal waters off the continental United States actually came from the Pacific Coast, from southern California in 1981. Habitat. Australian spotted jellyfishes usually inhabit warm coastal waters and lagoons and may float into estuaries and bays on flood tides. They appear to prefer water temperatures above 68°F (20°C) and salinities greater than 25 ppt. During the polyp stage of the life cycle, hard substrates are needed for attachment. Diet. These jellyfish use stinging cells to capture zooplankters, including the eggs and larvae of many fish and shellfish. They feed almost constantly since they can digest the entire content of their gut in two hours. They filter prodigious amounts of water each day, removing most of the small suspended particles. Except in the Gulf of Mexico, they also probably benefit from the primary production of zooxanthellae living in their umbrella tissues. Life History. Jellyfish undergo alternate generations with asexual and sexual stages in the life cycle. The visible organism is the adult medusa stage. Medusae occur as separate sexes that reproduce via external fertilization and produce freeswimming flat, ciliated larvae (planula). The planulae settle and attach to hard substrates and begin the polyp stage of the life cycle. Polyps develop into a form (strobila) that asexually produces free-swimming immature medusae (ephyrae). The young medusae mature over several weeks. Weak-swimmers, they become part of the plankton and are at the mercy of wind, currents, and tides. Australian spotted jellyfish in the Gulf of Mexico experienced huge population explosions in 2000 and again in 2007. During these episodes, the medusae appeared in large numbers along the Gulf Coast of the southeastern United States, apparently carried in the Loop Current and eddies of the Gulf Stream. In contrast to these irruptions, small populations are maintained year after year in places such as Terrebonne Bay, In the Gulf of Mexico, this large jellyfish is white because it lacks the Louisiana, and Indian River symbiotic algae that make it brown or bluish white elsewhere in its range. (Dwight Smith/Shutterstock.) Lagoon, Florida.

48 n INVERTEBRATES (ANNELID WORMS) Impacts. The 2000 invasion was costly to the Gulf of Mexico shrimp industry. The large gelatinous masses clogged nets and damaged gear and led to the closing of some productive areas to commercial fishing. Concern exists that such large infestations of jellyfish that coincide with the spawning season of many marine organisms could increase predation on fish eggs and the larvae of mollusks and crustaceans to such a degree that forage fish such as bay anchovy (Anchoa mitchilli) and oyster and crab populations in Mobile Bay and Mississippi Sound could be affected. With their massive consumption of zooplankton, the jellyfish potentially compete with native shrimp and fish for food and direct energy flow in aquatic ecosystems to themselves, a dead end in the food chain since jellyfish have few predators. Management. There seem to be no strategies for control or eradication currently available.

Selected References “Australian Spotted Jellyfish.” Field Guide to the Indian River Lagoon. Smithsonian Marine Station at Fort Pierce, n.d. http://www.sms.si.edu/IRLFieldGuide/Phyllo_punctat.htm. Burkhard, Elizabeth. “A Survey of the Relationship of the Australian Spotted Jellyfish, Phyllorhiza punc tata, and OCS Platforms.” GulfBase.org, n.d. http://www.gulfbase.org/project/view.php ?pid=asotrotasjppaop. Masterson, J. “Species Report: Phyllorhiza punctata von Lendenfield, 1884.” Smithsonian Marine Station at Fort Pierce, 2007. http://www.sms.si.edu/irlspec/Phyllorhiza_punctata.htm. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Phyllorhiza punctata (Jellyfish)”. ISSG Global Invasive Species Database, 2006. http:// www.invasivespecies.net/database/species/ecology.asp?si=992&fr=1&sts. Norris, Scott. “Australian Jellyfish Invade U.S. Waters.” National Geographic News, 2007. http:// news.nationalgeographic.com/news/2007/08/070827-jellyfish-invasion.html. Perry, Harriet. “Phyllorhiza punctata.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2010. Revised June 20, 2006. http://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=1192. “Phyllorhiza punctata von Lendenfeld, 1884.” Hawaii Biological Survey, Bishop Museum, 2002. http:// www2.bishopmuseum.org/HBS/invertguide/species/phyllorhiza_punctata.htm.

n Annelid Worms n European Earthworms Also known as: Nightcrawlers, red worms, leaf worms, red wrigglers, grey worms, angle worms Scientific names: Lumbricus terrestris, L. rubellus, Aporrectodea caliginosa, Dendrobaena octaedra, and others Family: Lumbricidae Native Range. The four species described below came from Europe. Of the known alien earthworms in the United States, 25 are European and 14 are of Asian origin. Not all are invasive. Distribution in the United States. Lumbricus terrestris and L. rubellus are found in two disjunct areas. The eastern invasion region extends from the Atlantic coast of North Carolina north through Maine and westward to the edge of the Great Plains. The western part of the distribution area reaches along the Pacific coast of California north through Washington and eastward to the foothills of the Rocky Mountains. Dendrobaena octaedra

EUROPEAN EARTHWORMS n 49

has a continuous distribution across the United States, avoiding the Atlantic and Gulf Coastal plains, Texas, the central Great Plains, most of New Mexico, and the southern parts of California and Arizona. Complete and accurate distribution data for Aporrectodea caliginosa are not available, but it is widespread in northern forests. Close relatives occur in grasslands, including the Palouse. Other exotic earthworms, including some from Asia such as the Alabama jumper (Amynthas agrestis), occur in south- Many of the alien earthworms in the United States, including the nightcrawler, red worm, angle worm, and octagonal-tail worm came from ern forests. Description. This entry per- Europe. tains to several different annelid or segmented worms from Europe, only a few of the 45 or more species introduced into the United States. Basic earthworm identification can be based on gross characteristics such as size, color, and the depth at which a species is found or the ecological group to which it belongs (see under Habitat). A more precise and advanced analysis of the species that are described in this entry relies on such anatomical details as the shape, size, and position of the clitellum and the setae, tiny bristles on the body used for locomotion. All of the adult worms are characterized by a smooth band or collar, the clitellum. The nightcrawler (Lumbricus terrestris) is the largest of the common invasive earthworms, attaining lengths of 5–8 in. (12.5–20 cm) or more. This reddish-brown anecic worm makes permanent vertical burrows to depths of 6 ft. (2 m). Its presence may be evidenced on the surface by a pile of casts (fecal material) and leaf stems some 2 in. (5 cm) across and 0.5– 0.75 in. (12.5–19 mm) high. The red or leaf worm (L. rubellus) is a medium-sized annelid ranging from 1–4 in. (2.5– 10.5 cm) long. Its back is reddish brown and irridescent; the underside is pale. This is an epi-endogeic species that occupies both the leaf litter and the uppermost few inches of the mineral soil. This is the species commonly sold as fish bait. The grey or angle worm (Aporrectodea caliginosa) is 2–6 in. (5–15 cm) long. It is unpigmented, but its internal organs and ingested food gives it a color ranging from gray or brown to greenish. This species is endogeic and makes horizontal burrows in the topsoil layer. The very small octagonal-tail earthworm (Dendrobaena octaedra) reaches lengths of only 0.6–2.5 in. (1.7–6 cm). They are reddish brown, darker on the back and head than the belly. An epigeic species, this earthworm is only found in the leaf litter or duff of the forest floor. Introduction History. European earthworms arrived in North America with early European settlers beginning in the sixteenth century. They were likely carried in soils used as ballast in ships and on the root balls of plants brought to the New World. Reinforcements continue to arrive in contaminated shipments of ornamental plants and intentional, permitted importations of live bait and composting worms from Canada, nightcrawlers, and red wrigglers (Eisenia veneta = E. hortensis), respectively.

50 n INVERTEBRATES (ANNELID WORMS) Northern forests developed after the Ice Age without native earthworms and are thus particularly vulnerable to invasion by hardy species from similar climate regions in Europe. On their own, earthworms spread very slowly, by an estimated 35 ft. (10 m) a year. In the 10,000 years that regions glaciated during the Pleistocene have been ice-free, native earthworms have been unable to recolonize most of the area from which they were eliminated by continental ice sheets. HowTop: Distribution of the octagonal-tail earthworm in the United States. ever, nonnative species have Bottom: Distribution of the nightcrawler (L. terrestris) and the red worm been deliberately and widely (L. rubellus) in the United States. (Both maps adapted from Proulx 2003.) introduced to agricultural areas and garden plots, where they are generally beneficial. Only recently have they invaded undisturbed forests and grasslands. In glaciated regions, numerous lakes attract sport fishermen, and they seem to be responsible for much of the spread of nightcrawlers and leaf worms into northern forests, as they often dump unused live bait on the ground. The construction and logging industries also move worms from place to place when cocoons and young worms become lodged in truck tires. Earthworm concentrations tend to be highest near roads and recreation areas. Homeowners bring composting worms and other garden worms to the forest edge as settlement spreads into new areas. Earthworms only reached central Minnesota, for example, as recently as the 1930s. Habitat. Many of the European earthworms now found in the United States are closely linked to disturbed and artificial habitats such as lawns, gardens, cultivated fields, and pastures. They have recently been invading hardwood forests. Creatures of the underground, they sort themselves into three main soil habitats. Anecic or deep-burrowing earthworms excavate vertical burrows as deep as 6 ft. (2 m), but feed on the surface. Enogeic species burrow into the topsoil to depths up to 20 in. (50 cm) and come to the surface to feed. They are responsible for much of the mixing of soil layers. Epigeic worms live in the litter and first inch or so of forest soils. They do not excavate burrows. A succession of earthworm species characterizes invasions of previously undisturbed forests. Epigeic species such as Dendrobaena are the pioneers; they are followed by endogenic types such as L. rubellus that prepare the soil for latecomers, the anecic nightcrawlers. Diet. Earthworms eat and decompose leaf litter and also consume decaying organic matter and microorganisms. Nightcrawlers pull leaf debris down into their burrows; stems and leaf fragments accumulate at the burrow entrance along with casts deposited by the burrow’s inhabitant and form what are called middens. The leaf worm and grey worm feed on surface litter, on organic material in humus-rich topsoil, and probably on fungi and bacteria in the

EUROPEAN EARTHWORMS n 51

rhizosphere, that nutrient-enriched area surrounding the roots of plants. The octagonal-tail earthworm feeds mainly on the bacteria and fungi of the litter layer. Life History. Earthworms are hermaphroditic, each individual possessing both testes and ovaries. They usually mate sexually with another individual, however, lining up “head to toe” so that the clitellum of one worm lies against the segments of the other that contain the male reproductive organs. The clitellum secretes a large amount of slime that encases the two worms in a slime tube. The sperm are released into the slime and carried in special grooves back to the sperm receptacles of the other individual. The worms then separate. A second mucous ring is secreted from the clitellum, and it slides forward over the body. As it passes the openings to the female organs, several ripe eggs are ejected, sticking to the ring. The ring continues to move forward and brings the eggs into contact with the sperm, which fertilize the eggs. The entire ring then passes over the head and away from the worm. Its ends seal to make a cocoon. The cocoon lies in the soil, into which tiny young worms emerge when the eggs hatch. Impacts. Earthworms are well known as beneficial additions to garden and agricultural soils, where they help decompose organic matter and accelerate nutrient cycles, aerate the soil and increase water infiltration with their burrowing, and mix soil layers to return nutrients to the root zone. They are the focus of a multimillion-dollar vermiculture industry that produces worms for composting and for live bait. It is therefore surprising to many people that they become a major ecological disaster when introduced to northern hardwood forests. In deciduous hardwood forests, invasive earthworms are “ecosystem engineers” that alter the habitat. They increase decomposition rates of the leaf litter to the degree that they destroy the duff and humus. These organic soil layers not only store nutrients until the spring growing season, but provide insulation and protection from predation for seeds and seedlings. In their absence, nutrients such as nitrates are leached, and seeds do not germinate; bare spots open to erosion develop. Exotic weeds such as garlic mustard (See Volume 2, Forbs, Garlic Mustard) (Alliaria petiolata) and Japanese barberry (See Volume 2, Shrubs, Japanese Barberry) (Berberis thunbergii) that evolved in the presence of earthworms can invade. The loss of the herb layer of native wildflowers such as trilliums (Trillium spp.), bloodroot (Sanguinaria canadensis), trout lily (Erythonium americanum) and blue cohosh (Caulophyllum thalictroides) has been noted in forests in The various introduced earthworms resemble each other but tend to be the Great Lakes area as a result found at different depths in the soil. (Vinicius Tupinamba/Shutterstock.)

52 n INVERTEBRATES (ANNELID WORMS) of earthworm invasions. The rare goblin fern or moonwort (Botrychium mormo) has been extirpated from some areas The litter is also habitat to a number of small vertebrates, invertebrates, and microbes. When it disappears, so do they. A more direct link may be made between earthworm invasions and declines in native salamanders that feed on worms. Larger worms such as leaf worms and nightcrawlers will be consumed by adult salamanders, but are too big to be ingested by juveniles. If the exotic earthworms replace native species, salamander recruitment could be significantly reduced. White-tail deer (Odocoileus virginianus) and earthworms may be connected to changes in the species composition of forest communities. Where deer yard up during winter, their feces accumulate and attract and nourish earthworms. An increase in earthworms reduces the litter layer and makes forest herbs more vulnerable to deer browsing. Together, they contribute to the loss of herbaceous plants and tree seedlings. Their deposition of casts, cementing together of soil particles while burrowing, displacement of other bioturbating organisms, and consumption of bacteria and fungi are some of the means by which earthworms alter the soil environment. With time, earthworm activities lead to soil compaction at depth. Compaction can bind some nutrients, prevent root penetration, reduce aeration and available soil moisture, and increase runoff and removal of phosphorus. The mixing of soil layers may change both the soil structure and its biochemical properties. It may increase weathering rates, but studies have yet to determine if the result will be a greater release of greenhouse gases to the atmosphere or increased storage of carbon in soils. Either negatively or positively, earthworms may be involved in climate change processes. Management. Prevention of the introduction of new species to the United States and the spread of existing invasive earthworms are paramount. Gardeners should not dispose of compost in natural areas, and fishermen should not dump unused live bait. Inspection of vermiculture products could ensure that the species being sold is truly the one intended and not some other that entered a batch through misidentification or contamination. The horticultural trade in live plants needs better control of accidental migrants in pots and root balls. Vehicle tires could be hosed down or otherwise sanitized before entering areas most vulnerable to invasion.

Selected References Baskin, Yvonne. Under-Ground. How Creatures of Mud and Dirt Shape Our World. Washington, DC: Island Press, 2005. Blatchford, John. “Earthworms Spread by Human Activity: Worms Improve Soil Fertility but Invasive Species do Damage.” Suite 101.com, 2009. http://zoology.suite101.com/article.cfm/ earthworms_spread_by_human_activity#ixzz0eJavfI9t. Dunne, Niall. “Invasive Earthworms—A Threat to North American Forests,” Plants and Gardens News: 19(1): 2004. http://chicagoconservationcorps.org/blog/wp-content/uploads2/2009/06/L40 %20Vermicomposting%20and%20Invasive%20Earth%20Worms.pdf. “Earthworm Ecological Groups.” Natural Resources Research Institute, University of Minnesota, Duluth, 2006. http://www.nrri.umn.edu/worms/identification/ecology_groups.html. Halsey, Daniel. “Invasive Earthworms: Affects on Native Soils.” Soil5125, University of Minnesota, 2009. http://southwoodsforestgardens.blogspot.com/2009/01/paper-on-invasive-european -worms.html.

ASIAN CLAM n 53 Proulx, Nick. “Ecological Risk Assessment of Non-Indigenous Earthworm Species.” Final draft. Minnesota Department of Natural Resources, 2003. http://www.nrri.umn.edu/WORMS/research/ publications/Proulx%202003.pdf.

n Mollusks n Asian Clam Also known as: Asiatic clam, gold clam Scientific name: Corbicula fluminea Family: Corbiculidae Native Range. East Asia, from southeastern China to Korea and southeastern Russia. Distribution in the United States. The Asian clam has established populations in all states except Alaska, Maine, Montana, New Hampshire, North Dakota, Rhode Island, South Dakota, and Wyoming. It also occurs in Puerto Rico. Description. This small freshwater bivalve is distinguished by a rounded to somewhat triangular shell with concentric, evenly spaced ridges. The umbo or raised area above the hinge is high and centrally positioned on the shell. On the inside of the valves, long, straight, serrated ridges, the lateral teeth, emanate from the hinge area, two on each side of the right valve and one on each side of the left valve. Three cardinal teeth project below the umbo on each valve. Two color morphs occur in the United States. In most parts of the country, shells are yellowbrown, but in the southwest, they are black. In the lighter-colored specimens, the inside of the shell is a glossy light purple nacre (mother-of-pearl); in dark morphs, the nacre is deep blue. Adult shell length rarely exceeds 1.5 in. (40 mm); usually it is less than 1 in. (25 mm). Related or Similar Species. Asian clams could be confused with native fingernail or pea clams (Family Sphaeriidae). Fingernail clams lack both lateral teeth and cardinal teeth and are typically less than an inch (25 mm) long. The Asian clam has a heavier shell than most native species. Introduction History. Asian clams were first collected in the United States in 1938 in the Columbia River near Knappton, Washington, but it is believed that they had probably occurred in some West Coast drainages since at least 1924. The clams were an important food for Chinese people, who may have deliberately brought them along when they emigrated to North America. It is also possible that they arrived accidentally in contaminated imports of the giant Pacific oyster (Crassostrea gigas), a shellfish first imported into Washington from Japan in 1903 and now the basis of a major aquaculture industry. Asian clams were discovered in the Ohio River in 1957 and quickly spread throughout the Mississippi River drainage system and into Lake Erie and Lake Michigan. On the Atlantic slope, they were first reported from Delaware in 1972, New Jersey in 1982, and Long Island, New York, in 1984. They were not expected to be able to survive New England’s cold winters, but were found in the lower Connecticut River in 1990 and in several Massachusetts reservoirs in 2007. In Hawai’i, the Asian clam first appeared at a farmer’s market on O’ahu in 1977. Within a few years, it was established in many streams and reservoirs on O’ahu as well as on the islands of Kaua’i, Maui, and Hawai’i.

54 n INVERTEBRATES (MOLLUSKS) One of the most recently documented invasions has occurred in Lake Tahoe. From a relatively few individuals spotted there in 2002, the population had exploded by 2009. These mollusks can disperse naturally within a water body, since juveniles float on currents. Overland transport is accomplished on contaminated boats, trailers, and aquatic sports gear, or, since they are used as fish bait, when unused bait is dumped into a stream, lake, or reservoir. Habitat. Asian clams inhabit the bottom sediments of streams, rivers, lakes, and ponds of all sizes, and will also invade irrigation canals. The substrate can be silt, sand, or gravel. They require well-oxygenated water, so they prefer flowing water and are intolerant of polluted water. However, they can withstand brackish water with salinities up to 13 ppt for short periods of time; and estuarine populations occur in the Chesapeake Bay and in San Top: Asian clams came from eastern Asia. Bottom: The Asian clam is Francisco Bay. Water temperainvasive in almost all states as well as in Puerto Rico. (Adapted from tures above 60°F (16°C) are USGS 2001.) needed for spawning and release of young. Asian clams can tolerate water temperatures as high as 86°F (30°C); they do not survive when temperatures drop below 35°F (2°C). In cold-weather regions such as the Great Lakes, there may be large fluctuations in population size from year to year. Diet. These filter-feeders are herbivores, consuming mostly phytoplankters sieved from the water column. Life History. Asian clams are hermaphrodites and capable of self-fertilization. Sperm are released into the water column and are taken in by other individuals. Eggs are fertilized in the inner gills, and there the larvae are incubated. Juveniles are released through the excurrent siphon when about 0.04 in. (1 mm) in size. They are poor swimmers and sink to the bottom, where they begin their adult stage. Reproduction and release of juveniles usually occurs twice a year, in the spring and again in late summer or fall. Juveniles become sexually mature at shell lengths of 0.2–0.4 in. (6–10 mm). Lifespan is one to four years.

ASIAN CLAM n 55

A. This small clam, usually less than 1.0 in. across, has a rounded shell with concentric, evenly spaced ridges and a high, centrally positioned umbo. (U.S. Geological Survey.) B. Asian clams with a nickel for scale. (Shawn Liston, Bugwood.org.)

Impacts. Asian clams are notorious biofouling organisms, clogging intake pipes of power plants and other facilities. The weak-swimming juveniles descend to the base of the water column from whence intake pipes usually withdraw water. Live animals, empty shells, and dead clam bodies are sucked in. This has proved to be a particular problem at nuclear power plants, where water is used for fire protection. Another type of economic consequence occurs where stream beds are dredged for sand and gravel to use as an aggregate in cement, as happens in Ohio and Tennessee. The clams end up in the cement but worm their way to the surface as it starts to set, leaving empty tunnels that weaken the structure. Large congregations of Asian clams can alter the benthic habitat, which they may come to dominate, and may compete with native fingernail clams for food and space. Recent studies in Lake Tahoe, for example, show an increase in a filamentous green alga (Zygnema sp.) in clam beds, probably thriving on the bivalves’ waste products. Management. Prevention of introduction to new bodies of water is the most effective way to slow or stop the invasion of Asian clams. Boats and equipment should be inspected, cleaned of any obvious attached plants and animals, and drained of all water on land before they leave the launch area. Bait buckets should be emptied on land, not in water. Before launching into another body of water, boats and all equipment should be cleaned in hot water and dried for several days. Chemical (bromine and chlorine) and mechanical (screens and traps) treatments can control infestations in intake pipes.

Selected References Balcom, N. C. “Aquatic Immigrants of the Northeast, No. 4: Asian Clam, Corbicula fluminea,” Connecticut Sea Grant College Program, 1994. Foster, A. M., P. Fuller, A. Benson, S. Constant, and D. Raikow. “Corbicula fluminea.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2009. http://nas.er.usgs.gov/queries/ FactSheet.aspx?speciesID=92. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Corbicula fluminea (Mollusc).” ISSG Global Invasive Species Database, 2005. http:// www.issg.org/database/species/ecology.asp?fr=1&si=537.

56 n INVERTEBRATES (MOLLUSKS) USGS. “Asian clam, Corbicula fluminea (Muller, 1774) (Mollusca: Corbiculidae)”. Nonindigenous Species Information Bulletin, Florida Caribbean Science Center, 2001. http://fl.biology.usgs.gov/ corbicula4.pdf.

n Asian Green Mussel Also known as: Green mussel, green-lipped mussel Scientific name: Perna viridis Synonyms: Mytilus viridus, Chloromya viridis Family: Mytilidae Native Range. Coastal waters of southern Asia from the Persian Gulf to southern China and the Philippines. Distribution in the United States. Gulf and Atlantic coasts of Florida northward through coastal Georgia as far as Charleston, South Carolina. Description. This large marine bivalve has a smooth, elongated, fan-shaped shell. The thin valves clearly show concentric growth rings; the ventral margin is concave on one side. The entire shell of juveniles is bright green, but in adults, it is brown with green margins. The inner shell surfaces are smooth and iridescent blue or blue-green. The beak, at the hinge, has interlocking teeth: two on the left valve and one on the right. Juveniles and adults secrete hairlike byssal threads with which to attach to hard substrates. Related or Similar Species. A number of native mussels in the same family as the Asian green mussel occur in states infested with this nonnative bivalve. They have similar shapes, but none are green. The scorched mussel (Brachidontes exustus), ribbed mussel (Guekensia demissa), and hooked mussel (Ischadium recurvum), the native species most apt to inhabit the same sites as Asian green mussels, have ribbed rather than smooth shells. The shells of the smaller horsemussels (Modiolus spp.) are brown on the outside and white on the inside. The smooth outer shell of the tropical charru mussel (Mytella charruana), another nonnative mussel found (rarely) in Florida’s waters, has a dark-brown wavy pattern on a lighter background; the inner shell is iridescent purple. Introduction History. Asian green mussels were first reported in Florida in Tampa Bay in 1999, when they clogged intake pipes at a power plant. This was probably the result of a discharge of ballast water carrying larvae by a ship coming from the Caribbean. Asian green mussels had arrived in Trinidad in 1990 and rapidly spread through the Caribbean. Drifting in currents, larval green mussels have dispersed southward as far as Marco Island, near Naples. A separate invasion event occurred near St. Augustine on the Atlantic side of the Florida peninsula in 2002. They likely arrived on a recreational or fishing boat transported overland from the Gulf coast without proper decontamination of hull, live wells, or gear. Northward-flowing ocean currents dispersed the mussel to Jacksonville, Florida, and along the entire Georgia coast by the end of 2003. In 2006, they were reported at Charleston, South Carolina. Mussels also dispersed southward; their range currently extends to near Titusville, Florida. Habitat. Asian green mussels inhabit coastal and estuarine waters in the intertidal and subtidal zones to depths near 35 ft. (10 m). They tolerate a wide range of salinities, from hypersaline (80 ppt) to brackish (12 ppt). Optimal salinity is reportedly 27–33 ppt. They also tolerate a wide range of temperatures between 50° and 95°F (10–35°C), but do best in water temperatures of 79–90° F (26–32° C). Juveniles appear to prefer to settle in areas of high water flow about 1 ft. (30 cm) below the low-tide mark. They seem to seek crevices or the undersides of floating objects. Diet. These mollusks are sessile filter-feeders. An incurrent siphon draws in seawater that is moved by cilia to the branchial cavity. Phytoplankters, zooplankters, and other organic

ASIAN GREEN MUSSEL n 57

particles are filtered out. Mucus is secreted to bind the food items into a bolus that is directed by cilia to the mouth. Water exits via an excurrent siphon. Life History. The sexes are separate animals that release eggs and sperm into the water column during spawning episodes that peak in spring and autumn. Fertilization takes place externally. The presence of gametes in the water stimulates other individuals to release eggs and sperm to synchronize spawning within a local population. The dilution of seawater, such as what happens at the onset of a rainy season, also seems to trigger spawning. Within 8 hours of fertilization, the embryos become ciliated, free-swimming larvae and, 8–12 hours later, have a shell and ciliated membrane called a velum. The larvae metamorphose into juveniles and settle 8–20 days later. The juveniles secrete byssal threads and attach to hard surfaces. In Tampa Bay, they reportedly become sexually mature in Top: The Asian green mussel is native to coastal waters of southern Asia. 1–2 months when shell length Bottom: In the United States, the Asian green mussel is invasive along is 0.6–1.2 in. (15–30 mm). both the Gulf and Atlantic coasts of Florida and has currently expanded its range as far north as South Carolina. (Adapted from McGuire and They live about three years. Impacts. Asian green mus- Stevely 2009.) sels are marine biofouling organisms, acting much like the freshwater zebra mussel (see Mollusks, Zebra Mussel). They can clog intake screens and pipes of power and desalinization plants and cover the hulls of boats and submerged parts of buoys, bridges, piling, and seawalls. Not only do they block the flow of water, but they also damage pumps, reduce heat transfer efficiency, and accelerate the rate of corrosion of metal surfaces. Economic impacts of increased plant maintenance can be significant. Since the Asian green mussel can rapidly build up large populations that form mats on the seafloor, it is suspected that they will complete for space and possibly for planktonic food supplies with native bivalves. In Tampa Bay, green mussels seem to have expanded at the expense of native oysters (Crassostrea virginica). Elsewhere, for example in Georgia, where oysters live in habitats where they are exposed at low tide, such replacement does not seem to be happening.

58 n INVERTEBRATES (MOLLUSKS)

A. Asian green mussel shell shows distinct beak and concentric growth rings. (U.S. Geological Survey.) B. The concave ventral margin and smooth inner shell surfaces are visible on some of these specimens. (U.S. Geological Survey.)

The success of the invasion of Asian green mussels in the coastal waters off Florida suggests they would be equally successful if accidentally introduced to other sites along the Gulf coast or to southern California. Management. Currently, most management consists of mechanically removing mussels from intake screens and pipes or flushing those systems with chlorinated water. The main focus is to prevent further introductions of the organisms by educating commercial fishermen and recreational boaters and fishermen to inspect and clean the hulls of their vessels and to drain live wells and bilges on land after taking their boats out of the water.

Selected References Masterson, J. “Species Report: Perna viridis.” Smithsonian Marine Station at Fort Pierce, 2007. http:// www.sms.si.edu/irlSpec/Perna_viridis.htm. McGuire, Maia, and John Stevely. “Invasive Species of Florida’s Coastal Waters: The Asian Green Mussel (Perna viridis).” Publication #SGEF 175, Florida Sea Grant College Program. Institute of Food and Agricultural Sciences (IFAS), University of Florida, 2009. http://edis.ifas.ufl.edu/sg094. Powell, Cindie. “Asian Invader Musseling in on U.S. Habitats.” Texas Sea Grant and NOAA, 2005. http://www.oar.noaa.gov/spotlite/archive/spot_greenmussel.html. Thornton-DeVictor, Susan, and David Knott. “The Asian Green Mussel: Recent Introduction to the South Atlantic Bight.” Species of the Month, Southeastern Regional Taxonomic Center, South Carolina Department of Natural Resources, n.d. http://www.dnr.sc.gov/marine/sertc/The% 20Asian%20Green%20Mussel.pdf.

n Chinese Mystery Snail Also known as: Asian applesnail, Japanese mystery snail, black snail, trapdoor snail Scientific name: Cipangopaludina chinensis malleata Synonyms: Bellamya chinensis, Viviparus chinesis, Viviparous stelmaphora, Paludina malleata et al. Family: Viviparidae

CHINESE MYSTERY SNAIL n 59

Native Range. Southeast Asia. It occurs in Myanmar (Burma), Thailand, Indonesia (Java), Vietnam, China, Korea, Japan, and the Philippines. Distribution in the United States. Chinese mystery snails are reported in 27 states. In the eastern United States, populations occur in New England and the Great Lakes region, and on the West Coast, they can be found from the San Francisco Bay area north to Seattle. Mid-continent records come from Colorado, Iowa, Nebraska, Oklahoma, Texas, and Utah. Description. These gastropods are distinguished by their large size, adults reaching lengths of 1.5 in. (60–65 mm) from the tip of the whorl to the lip of the shell. The shell has 6–7 whorls with rounded shoulders and indented sutures; in adults, it is a uniform olive green, greenish brown, brown, or reddish brown without banding on the outside and white to pale blue on the inside. The dark solid operculum, a func- Top: The Chinese mystery snail is native to Southeast and East Asia. tioning “trapdoor,” is marked Bottom: Chinese mystery snails are reported from 27 states. (Adapted with concentric rings. The outer from Kipp and Benson 2007.) lip is round to oval and black. Related or Similar Species. Taxonomic confusion exists as to whether there are two forms of the Chinese mystery snail in the United States, or whether the Japanese mystery snail (C. japonica) is a separate species with a more elongate shell and other subtle morphological differences. The banded mystery snail (Viviparus georgianus), native to some parts of the United States but an introduced species in the Great Lakes region and eastern states north of the Carolinas, is smaller than the Chinese mystery snail, with a maximum shell length of 1.75 in. (45 mm); its shell is encircled with obvious reddish-brown bands. The brown mystery snail (Campeloma decisum), native to the eastern United States, only rarely grows as large as the Chinese mystery snail and is much narrower than either the Chinese or banded mystery snails. Its shell is usually olive green. The brown mystery snail is one of very few native snails with an operculum. Introduction History. The earliest record of Chinese mystery snails in the United States dates to 1892 and San Francisco, where they were imported for the live-food market.

60 n INVERTEBRATES (MOLLUSKS) By 1911, a free-living population was thriving in San Francisco Bay. Snails may have been accidentally introduced into Massachusetts in the early 1900s with goldfish released to control mosquitoes. A population was established in Boston by 1915, perhaps a by-product of the local Asian food market. Snails entered Lake Ontario from the Niagara River between 1931 and 1942. Chinese mystery snails were reported in Florida in 1950 and were established in Texas and Lakes Erie and Michigan and their drainages by 1965. Snail The shell of the Chinese mystery snail has indented sutures between the introductions initially seem to rounded whorls. (Pieter Johnson, University of Colorado.) have been intentional releases either to develop a local food supply or from the freshwater aquarium trade, in which Chinese mystery snails are used to keep fish tanks clean of algae growths. They may be unintentionally moved from one body of water to another as contaminants in live bait (e.g., minnows and crayfish) or on plants and in water transported on recreational watercraft and boat trailers. It takes only one pregnant female to start a new population. Habitat. These freshwater snails prefer quiet waters with soft substrates of silt, sand, or mud. They can be found in lakes, ditches, rice paddies, and slow-moving streams at water depths of 1.5 to 15 ft. (0.5 to 5 m). They can tolerate pollution and may thrive in stagnant water, but they cannot survive very low oxygen levels and experience major die-offs under a combination of warm water and algal blooms that reduce dissolved oxygen content. Diet. Chinese mystery snails feed on organic and inorganic material on the bottom of water bodies and scrape algae from hard surfaces. They also consume zooplankters and phytoplankters. Life History. These snails are live-bearers. In the eastern United States, embryos develop in the female between May and August, and the young are born in shallow water from June through October. After birthing, females retreat to deeper water for the winter months. Each female may produce as many as 100 tiny snails in a single brood. (It is the sudden appearance of tiny, perfectly developed snails that may be the “mystery” of these snails.) Females live up to five years and tend to have their largest broods in their later years. Males live on average three years. Impacts. The ecological impacts, if any, of this introduced species remain unknown. It is possible they could compete with native snails for food and space, but little indication exists that this is happening. Chinese mystery snails do carry parasites, including one that can infect humans, but do not seem to be a vector for “swimmer’s itch” as some have feared. The species can clog the screens of even large water-intake pipes. Management. Prevention of new infestations is the best control measure available. Eradication of existing populations is likely impossible. People should refrain from dumping

COMMON PERIWINKLE n 61

bait and aquarium contents and should sanitize fishing and boating equipment before entering another body of water. Live animals of any sort should never be released into the wild.

Selected References “Aquatic Invasive Species: Chinese Mystery Snail.” Indiana Department of Natural Resources, 2005. http://www.in.gov/dnr/files/CHINESE_MYSTERY_SNAIL.pdf. Kipp, Rebekah M., and Amy Benson. “Cipangopaludina chinensis malleata.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2007. http://nas.er.usgs.gov/queries/FactSheet.asp ?speciesID=1045. “Mystery Snail Monitoring Protocol.” Aquatic Invasive Species Monitoring Manual—Citizen Lake Monitoring Network, 2009. http://www.uwsp.edu/cnr/uwexlakes/clmn/.

n Common Periwinkle Also known as: Edible periwinkle, wrinkle winkle Scientific name: Littorina littorea Family: Littornidae Native Range. Europe, from the coast of northern Spain, throughout the British Isles, and north to Scandinavia and Russia. Distribution in the United States. Established along the coast of the northeastern United States, from Maine to Virginia and the Chesapeake Bay. On the West Coast, individuals have been collected from California to Washington. Description. This small marine snail has a conical shell that comes to a point at the apex. Shells of young animals show distinct ridges spiraling up to a prominent point; in adults, the ridges become indistinct and the shell appears smooth. Five or six somewhat swollen whorls are outlined by shallow sutures. The base color of the shells is usually grayish brown or black, getting paler near the top. Dark lines form a spiral pattern on much of the shell, but the central axis or columella is white, as is the inside of the shell. The thick inner lip of the aperture is bent over the columella. Average shell height is 0.6–1.5 in. (16–38 mm), but it may be as great as 2.0 in. (52 mm). Juvenile stages have black barring on their flat, broad tentacles. Related or Similar Species. The ridged shells of young common periwinkles could be mistaken for those of the rough periwinkle (Littorina saxatilis), which is native to the coasts of eastern North America from the Chesapeake Bay northward. Rough periwinkles have 4–5 whorls and grow to only about 0.7 in. (18 mm). The exterior of the shell may bear a checkered pattern; the inside is brown. They tend to inhabit salt marshes, but can be found on rocky coasts. Rough periwinkles have been introduced to San Francisco Bay Introduction History. Live common periwinkles were first identified in North America in 1840 at Pictou, Nova Scotia, Canada. From this site in the Northumberland Straits of the southern Gulf of St. Lawrence, it moved to the Atlantic Coast, being discovered in Halifax, Nova Scotia, in 1854. By 1861–1862, it had appeared at Eastport, Maine. Soon thereafter, it was found on Cape Cod (1872), and by 1890, it had reached Cape May, New Jersey. It appears that a separate introduction occurred sometime in the early 1950s on the Delmarva Peninsula. Southward expansion from this point of entry was relatively slow; it took about 25 years to reach the entrance to Chesapeake Bay (1978), its current southern range limit.

62 n INVERTEBRATES (MOLLUSKS) It is generally agreed that the common periwinkle arrived in Nova Scotia from Great Britain on rocks used as ballast in transoceanic ships, possibly those involved in the early and midnineteenth-century timber trade. The initial inoculation was followed by rapid population growth and range expansion along the rocky coasts and salt marshes of New England. However, not all agree with this scenario and raise the possibilities that (a) the periwinkle was actually native to northeast Canada and experienced a range expansion only after European settlement; or (b) that it was carried to Canada by the Vikings in pre-Columbian times. Most evidence to date, including information from prehistoric and historic archaeological sites and modern genetic analyses, support a nineteenth-century introduction. Habitat. These mobile gastropods inhabit coastal and estuarine environments. The most typical habitat for common periwinkles is on all but Top: The common periwinkle is native to the Atlantic and Baltic coasts of the most exposed rocky coasts Europe. Bottom: The common periwinkle is a dominant member of rocky in the intertidal zone from the coast communities in the northeastern United States and has been spray zone of the upper littoral collected in California and Washington State. (Adapted from Benson 2009.) to the sublittoral zone that is exposed only during the lowest low tides. In sheltered areas, they may found in salt marshes and on mudflats. Diet. Common periwinkles are herbivores and graze on benthic diatoms and dinoflagellates as well as macroalgae such as sea lettuce (Ulva lactuca) and other large green algae and young and ephemeral red and brown algae. While grazing on rocks, they may ingest small invertebrates such as barnacle larvae. Life History. Common periwinkles have separate sexes and reproduce annually. Females release their fertilized eggs into the ocean in horny capsules about 0.03 in. (1 mm) wide. Each capsule is convex on both sides and usually contains 2–3 eggs, although as many as 9 eggs may be inside. The shedding of egg capsules coincides with spring tides (i.e., when the tidal range is greatest). The larvae exit the capsules and settle within six weeks. Juveniles mature at 2–3 years of age when shell height is about 0.4 in. (10 mm). The lifespan of a common periwinkle is 5–10 years.

COMMON PERIWINKLE n 63

A. Common periwinkles are one of the most common mollusks in intertidal communities north of New Jersey. (J. Pederson. Reprinted with permission of the MIT Sea Grant College Program.) B. The conical shell spirals up into a prominent point, while the inner lip of the aperture folds over the columella. (Amy Benson, U.S. Geological Survey.)

Impacts. Common periwinkles quickly became one of the most common mollusks on the Atlantic Coast north of New Jersey and an ecological dominant in intertidal communities. In both exposed rocky coast habitats and estuarine situations densities may reach 20–45/sq. ft. (200–500/m2). Its consumption of green algae has allowed Irish moss (Chondrus crispus), a slow-growing foliose red alga, to proliferate. Constant grazing by periwinkles of young algae prevents the reestablishment of the original algal canopy on rocks and removes a key food item of native marine snails. On rocky coasts, common perwinkles have displaced the eastern mudsnail (Nassarius obsoletus) from many habitats and caused a niche shift and population reduction in the rough periwinkle (Littorina saxatilis). In estuarine habitats, its bulldozing of soft sediments slows the accumulation of fine materials and stifles the growth of the root mat of salt marsh cordgrass (Spartina alterniflora). Management. Few management practices have been developed to deal with common periwinkles, and little research is conducted on them. They are today well-established members of intertidal communities. Indeed, they may gain value as a bio-indicator of contaminated marine habitats.

Selected References Benson, A. J. “Littorina littorea.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2009. http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=1009. Chapman, John W., James T. Carlton, M. Renee Bellinger, and April M. H. Blakeslee. “Premature Refutation of a Human-Mediated Marine Species Introduction: The Case History of the Marine Snail Littorina littorea in the Northwestern Atlantic.” Biological Invasions 9: 737–50, 2007. doi:10.1007/s10530-006-9073-x. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Littorina littorea (Mollusc).” ISSG Global Invasive Species Database, 2005. http:// www.issg.org/database/species/ecology.asp?si=400&fr=1.

64 n INVERTEBRATES (MOLLUSKS)

n Giant African Snail Also known as: Giant African land snail Scientific name: Achatina fulica Family: Achatinidae Native Range. East Africa, particularly the coastal areas of Kenya and Tanzania. Distribution in the United States. Established only in Hawai’i, but its potential to invade the continental United States is a source of major concern. Snails have been collected in California, several southern states, and in Michigan, Ohio, and Wisconsin. A small but rapidly expanding population in Florida was eradicated in 1973. Description. This large terrestrial snail can reach lengths near 8 in. (20 cm). The coneshaped shell makes up roughly half the total length. An adult giant African snail stands about 3 in. (7–8 cm) high. The shell is usually reddish brown with cream and dark-brown streaks running perpendicular to the whorls, but a light “cafe´ au lait” color is also common. The shells of adults narrow toward the apex, which is barely drawn out. They have 7–9 whorls with indented sutures. The semielliptical opening takes up less than half the shell length and has a sharp, thin outer lip. The inner lip (columella and parietal callus) is pale blue or whitish. This land snail is much larger than any native species. Related or Similar Species. Other large African land snails could invade the United States. These include the world’s largest land snail, the Ghana tiger snail (Achatina achatina); margies or West African land snail (Archachatina marginata); and the Nigerian land snail (Limicolaria aurora). None of these have been Top: The giant African snail comes from coastal regions of East Africa. found free-living in the United Bottom: The giant African snail is an invasive species only in Hawai’i at this time, but it is frequently smuggled into other parts of the United States to date. Introduction History. Twice, States, risking establishment of new populations elsewhere. giant African snails were illegally

GIANT AFRICAN SNAIL n 65

A. Darker forms of the giant African snail infest this tree. (David G. Robinson, USDA APHIS PPQ, Bugwood.org.) B. This large terrestrial snail can reach lengths of 8 in., making it much larger than any native snail species. (Forest and Kim Starr.)

imported into hatcheries on Maui, Hawai’i, in 1936, once by mail and once brought in luggage from Japan. It was bred there and, shortly afterward, on O’ahu. By the time they were discovered by authorities, escapees had established large colonies on both islands. In 1958 the snails appeared on Kaua’i and Hawai’i. By 1963, they had been discovered on Moloka’i and possibly Lana’i. Between 1948 and 1958, snails were intercepted by quarantine officials on cargo coming into San Pedro and other California ports at least 50 times. However, children returning from visits to Hawai’i were more successful in smuggling the snails into Arizona (Mesa) and Florida (Miami) in 1958 and 1966, respectively. The contraband was released outside when discovered by family members. In Arizona, the snails were quickly eradicated, but the case in Florida became a cautionary tale that still argues against allowing this species anywhere in the United States. The Miami family decided to keep the snails as pets and set them out in the family garden. Within seven years, more than 18,000 giant African snails occupied 42 city blocks in Miami. Another infestation was reported north of the city in Hollywood. It took 10 years and a million dollars for Florida to eradicate them, mostly by hand collection. Snails still arrive at U.S. ports as part of an illegal pet trade and unintentionally in shipping containers and on plants imported from Hawai’i. Snails appeared in the Midwestern states of Michigan, Ohio, and Wisconsin as part of the pet and shell trades and in response to requests from teachers looking for classroom animals and unaware of the threats posed to agriculture, horticulture, and possibly human health by these attractive, easy-to-care-for gastropods. Local dispersal of eggs, and snails if populations were established, would be facilitated by the movement of garden waste, rubbish, construction materials, vehicles, and other equipment away from contaminated areas. The snails themselves are capable of moving 150 ft. (50 m) a night. It only takes one gravid female to start a new population. Habitat. Native to humid tropical forests, the giant African snail is highly adaptable and could survive in temperate climates, even those with snow. It can also withstand drier environments because it can seal itself inside the shell and aestivate in loose soil during

66 n INVERTEBRATES (MOLLUSKS) unfavorable conditions. It is active at temperatures of 48–84°F (9–29°C); at lower temperatures, it becomes dormant. In the tropics, this land snail inhabits disturbed forests and forest edge, shrublands, and wetlands and has invaded agricultural areas, gardens, and urban areas. It is nocturnal; sunlight can be lethal. Diet. Giant African snails are herbivores and detritivores and reportedly consume some 500 different types of medicinal and ornamental plants as well as food crops, including such temperate-zone species as beans, cucumbers, melons, peanuts, and peas. Young snails with shells up to an inch (3 cm) long are almost completely vegetarian; older individuals increasingly feed on detritus and decaying plant material, although they still feed on live plants. Life History. The giant African snail is hermaphroditic, each individual possessing both male and female reproductive organs, but must breed with other individuals to produce fertile eggs. Snails lay their first eggs at six months and are able to produce eggs for another 400 days, with as many as three clutches a year. During their first year, they may lay 100 eggs, and in their second year, up to 500. After that time, fecundity decreases. The usual lifespan of a snail is 5–6 years. The large eggs are about 0.2 in. (4.5–5.5 mm) in diameter and deposited in nests excavated in the soil or under leaves and loose stones. They hatch from a few hours to 17 days after laying, depending upon temperature. They require temperatures above 59°F (15°C). The hatchlings remain below ground for 5–15 days, where they consume their egg shells and organic detritus. They remain close to the nest during this time, but within two months will establish a new home range and begin feeding aboveground on green plants at night. Impacts. The greatest threat posed by giant African snails is to commercial agriculture because they are capable of devouring tree crops, ornamentals, and vegetables. Florida’s tropical plant industry would be particularly vulnerable. The snails could also transmit parasites to humans. They are carriers for rat lungworm (Angiostrongylus cantonensis), a nematode that produces eosinophilic meningitis in humans. In natural island habitats, such as in Hawai’i, they may compete with native snails. Because of its voracious appetite and importation into many tropical islands in the Pacific and Caribbean as well as Southeast Asia, these snails are considered the world’s worst pest snail and have been nominated by IUCN as among 100 of the world’s worst invaders. Management. In Hawai’i and Florida, a number of biocontrol measures were tried, the more successful ones involving the importation of carnivorous snails from various parts of the world, including Euglandina rosea and Gonaxis quadrilateralis. These seemed to depress recruitment in giant African snails but did not eliminate them altogether. Success in Florida came with labor-intensive and thus expensive baiting and hand collection. (In other parts of the world, pesticides are used to control populations.)

Selected References Davis, C. J., and G. D. Butler Jr. “Introduced Enemies of the Giant African Snail, Achatina fulica Bowdich, in Hawaii (Pulmonata: Achatinidae).” Proceedings, Hawaiian Entomological Society, 60(3): 377–89, 1964. Available online at http://scholarspace.manoa.hawaii.edu/bitstream/10125/10889/ 1/18_377-390.pdf. IUCN/SSC Invasive Species Specialist Group (ISSG). “Achatina fulica (Mollusc).” ISSG Global Invasive Species Database, 2006. http://www.issg.org/database/species/ecology.asp?si=64&fr=1&sts=sss. Robinson, D. G. “Identity: Achatina fulica Bowdich, 1882.” U.S. Department of Agriculture, Animal and Plant Health Inspection Service, 2002. http://www.aphis.usda.gov/plant_health/plant_pest_info/ gas/downloads/achatinafulica.pdf.

GOLDEN APPLE SNAIL n 67 Stokes, Heather. “Giant (East) African Snail (Achatina fulica).” Introduced Species Summary Project. Columbia University, 2006. http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/ inv_spp_summ/Achatina_fulica.htm.

n Golden Apple Snail Also known as: Channeled apple snail, applesnail Scientific name: Pomacea canaliculata Family: Ampullariidae Native Range. South America, from temperate Argentina into the Amazon basin. It occurs in Argentina, Paraguay, and Uruguay in the La Plata basin and in Brazil and Bolivia in the Amazon basin. Distribution in the United States. Established on Maui, Kaua’i, O’ahu, and Hawai’i islands in Hawai’i; a couple of isolated sites in southern California; northern Florida near Jacksonville; a threecounty area in southeastern Texas at the heart of the state’s rice-growing region; and a site near Fort Worth in northern Texas. It has been reported from Mobile, Alabama; Yuma, Arizona; Georgia; Louisiana; North Carolina; and Oklahoma. Description. This freshwater snail is fairly large; its globular shell measures 2.75–3.6 in. (7.0–9.0 cm) high. Deeply indented sutures or channels separate one whorl from the next. The apical spire progresses in steps to a prominent point on top; the spire has nearly flat shoulders. Shell color in wild forms is olive brown to yellowish brown, often with dark bands; those bred in captivity may have yellow and green shells. The large opening (aperture) may be round or

Top: The golden apple snail is native to the Amazon and La Plata basins of South America. Bottom: Golden apple snails are established on Hawai’i and in isolated locations of southern California and northeastern Florida. They have been found not far from Texas’s rice-growing region, where they would pose a major threat to the crop. (Adapted from USGS. “Pomacea canaliculata.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2010. http://nas.er.usgs.gov/queries/ FactSheet.asp?speciesID=980.)

68 n INVERTEBRATES (MOLLUSKS)

A. The shell of this immature golden apple snail shows the indented sutures between whorls and the flatshouldered apex that distinguish this species. B. The large apertures are visible on specimens in this group of adult snails. (Susan Ellis, Bugwood.org.)

oval. The thick, retractable operculum has a concentric structure with the nucleus near the center. Eggs are bright pink. Related or Similar Species. The taxonomy of apple snails is not completely resolved, and it may be that a complex of closely related species exists. Several common and scientific names have been used in the literature, and misidentification of invaders has added to the general confusion. In Florida, there are four other apple snails, one of which, the Florida apple snail (P. paludosa) is native to peninsular Florida. It has a distinctively low, rounded shell spike and is much smaller (shell height 1.6–2.75 in. [4.0–7.0 cm]) than the golden apple snail. The eggs of Florida apple snails are white and relatively large. Genetic studies reveal that the most common introduced apple snail in that state is the island apple snail, P. insularum, and not P. canaliculata as previously thought. The two are very similar in canaliculata appearance. Introduction History. Golden apple snails were brought to Southeast Asia in 1980 as a potential food source for local peoples and possibly an export to the gourmet markets of Asia. They were taken to Hawai’i from the Philippines for similar reasons in 1989. Elsewhere in the United States, they entered as part of the pet and aquarium trade, of which they became part in the 1950s. It is likely that infestations in the continental United States are the result of escapes or releases of pet snails. The snail (or a close relative) was in Palm Beach County, Florida, in 1978 and in three other central Florida counties by the late 1990s. A small population existed in a reservoir in Rockingham County, North Carolina in 1993, but did not become established. Golden apple snails were found to be established in Lake Miramar in San Diego County and in a small pond at the Norton Simon Museum in Pasadena, California, in 1997. Live snails and egg masses were retrieved from a canal near the Salton Sea in Riverside County, California, in 2001. Texas Parks and Wildlife discovered the snail in a rice irrigation canal near Houston in 2001, and surveys revealed their presence in canals and bayous in three counties in the southeastern part of that state. Flooding resulting from Tropical Storm Alison in June of that year probably dispersed them to other sites in the area.

GOLDEN APPLE SNAIL n 69

Habitat. Native to lakes and swamps, in the United States, the golden apple snail is found in urban ponds, drainage and irrigation ditches, natural streams, bayous, wetlands, and rice and taro fields, which are regularly flooded. It feeds at night and spends the day submerged among aquatic plants. This apple snail withstands periods of drought by burrowing into the bottom and retracting its operculum to seal the shell. They may aestivate as long as five months and can also hibernate for long periods of time during cold weather. Diet. Golden apple snails are herbivores and consume most types of aquatic vegetation. They show a strong preference for taro and rice. Unfortunately, they will not feed on two invasive aquatic plants, hydrilla (See Volume 2, Aquatic Plants, Hydrilla) and waterhyacinth (See Volume 2, Aquatic Plants, Waterhyacinth). Life History. Golden apple snails are sexually mature when they are about 1 in. (2.5 cm) in size or between three months and two years of age. Females crawl out of the water at night and deposit clusters of pink eggs on just about any solid surface protruding above the waterline. The eggs are 0.09–0.14 in. (2.2–3.5 mm) in diameter, and each clutch may contain 200–600 eggs or more. Depending upon ambient temperature, the eggs will hatch in 7–15 days. A female will produce a new clutch every few weeks and can breed throughout the year, although reproduction is depressed in cooler months. Golden apple snails will live about four years. Impacts. The golden apple snail is a major agricultural pest in Hawai’i, where it attacks taro and rice. They feed on the corm and create holes that give access to bacteria and other plant pathogens, either killing the plant or greatly reducing its yield. They also consume young shoots of taro, rice, and other water plants. Elsewhere in the United States, they have not become a problem yet because they are generally in nonagricultural areas or, as near the Salton Sea, in areas where the crops grown are not those likely to be attacked by these gastropods. Only the populations in southeastern Texas, close to rice fields, are cause for concern and have prompted more widespread recognition of the potential harm caused by these invaders. So far, crop damage has not been observed in Texas. (It should be noted that golden apple snails have been very destructive of rice and taro crops in Southeast Asia. For this reason, they have been nominated by the IUCN as one of 100 of the world’s worst invasive species.) In Florida, there is concern that exotic apple snails could outcompete the native apple snail, P. paladosa, which is the primary food of the rare and endangered Everglades Kite (Rostrhamus sociabilis). Golden apple snails can transmit rat lungworm (Angiostrongylus cantonensis) if they are improperly cooked, causing severe headache, fever, and even death in people who eat them. Management. In Southeast Asia, where the golden apple snail is such a threat to agriculture, several methods of biological control have been attempted with little success. Among the predators brought in to eat snails are ducks, carp, Nile tilapia, and red ants, which eat snail eggs. Toxic plants grown in rice paddies or left to float on the surface did kill the apple snails, and control of water levels helped. Laborious hand-picking appears to be the most effective means of control, but eradication is nearly impossible. Blocking new introductions is the best way to prevent the spread of this pest.

Selected References Cowie, R. H. “Ecology of Pomacea canaliculata.” ISSG Global Invasive Species Database, 2004. http:// www.issg.org/database/species/ecology.asp?si=135&fr=1&sts=.

70 n INVERTEBRATES (MOLLUSKS) Ghesquiere, Stijn A. I. “Pomacea (pomacea) canaliculata (Lamarck, 1819).” The Apple Snail Website, n.d. http://www.applesnail.net/content/species/pomacea_canaliculata.htm. Howells, Robert G., and James W. Smith. “Status of the Applesnail Pomacea canaliculata in the United States.” The Seventh International Congress on Medical and Applied Malacology (7th ICMAM) Los Ban˜ os, Laguna, SEAMEO Regional Center for Graduate Study and Research in Agriculture (SEARCA), Philippines, 2003. http://www.applesnail.net/pestalert/conferences/icam07/country _report%20_usa.pdf. Mohan, Nalini. “Apple Snail (Pomacea canaliculata).” Introduced Species Summary Project. Columbia University, 2002. http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/inv_spp_summ/ Pomacea_canaliculata.html. Strange, Lionel A., and Thomas R. Fasulo. “Apple Snails of Florida.” University of Florida, 2004. http:// entnemdept.ufl.edu/creatures/misc/gastro/apple_snails.htm.

n Naval Shipworm Also known as: Atlantic shipworm, great shipworm Scientific name: Teredo navalis Family: Teredinidae Native Range. Naval shipworms have been transported around the world in the hulls of wooden sailing ships for centuries. It is difficult to know, therefore, just what their native range is. The Atlantic coast of Europe from Iberia to Scandinavia is the most likely place of origin. Today the species is cosmopolitan, found in tropical and subtropical waters of the Atlantic and Pacific oceans in both the Northern and Southern hemispheres. Distribution in the United States. Naval shipworms are found in all coastal regions of the United States. Description. Although called a worm, this animal is mollusk, a somewhat bizarrely formed bivalve adapted to boring into and living in wood. The reddish body is long and wormlike and topped by a very small shell that serves to chip away wood. Most contemporary information on them comes from the Baltic Sea, where they regularly attain lengths of 8–12 in. (20–30 cm) and a width of 0.4–0.8 in. (1–2 cm). In tropical waters, they reportedly become nearly 20 in. (50 cm) long. The shell is ridged and covers but a small part of the body; it is usually 0.5–0.8 in. (12–20 mm) in length. Frequently, the burrows that shipworms dig in submerged wood are the chief indication that the animals are present. Each burrow is a long cylindrical tube lined with a calcareous coating secreted by the shipworm. It is blocked near the entrance by a pair of calcareous structures or “pallets” that are paddle-shaped. Burrows excavated by adults can be as much as 3 ft. (1 m) long, but larvae with diameters of 0.04 in. (1 mm) also bore into wood. The shipworm extends two siphons from its anterior end through a small opening between the pallets for feeding, respiration, and excretion of wastes. Related or Similar Species. There are native species of shipworm in several genera, including six species in the genus Teredo, found along the Atlantic coast; and others that are introduced or of unknown origin. Introduction History. The naval shipworm was first reported in the United States in 1839, when it was detected in the sheathing of a foreign wooden ship in Massachusetts Bay. Within 100 years, it was common all along the Atlantic coast north of the bay. Naval shipworms showed up in Long Island Sound in 1869 in the hull of a sailing ship, and within a few decades, they were common in New York Harbor. The first naval shipworms were

NAVAL SHIPWORM n 71

detected in Chesapeake Bay in 1878, but it remained rare. Later, it was collected from North Carolina south to Florida and along Texas’s Gulf coast, as well as in Puerto Rico. An invasion on the Pacific coast in San Francisco Bay occurred in 1913 with drastic results (see under Impacts). Today, the naval shipworm is less abundant as a result of many fewer wooden-hulled ships and the widespread use of chemically treated timbers in waterfront construction. Habitat. Shipworms live in timbers submerged in seawater, including the hulls of wooden ships and pilings, piers, and other wooden waterfront structures. They tolerate a wide range of salinities (5–45 ppt), so they also thrive in estuaries. Larvae probably die in salinities less than 5 ppt. Shipworms reproduce at water temperatures ranging from 52–86°F (11–30°C), but are known to survive in water temperatures as low as 33°F (0.7°C). They are found in tropical seas as well as cool tem- Top: Naval shipworms are found around the world as a consequence of perate waters. They survive up global trade and explorations, especially in the days of wooden-hulled to six weeks in oxygen-poor sit- ships. Their origins are obscured but are likely to have been in the uations by sealing themselves Atlantic waters off Europe. Bottom: Shipworms are found in all coastal into their burrow and metaboliz- waters of the United States. ing stored glycogen. Diet. Shipworms feed almost exclusively on wood with the aid of symbiotic bacteria that digest cellulose and fix nitrogen. The bacteria reside in special cells in the gills. The specially sculptured shell rasps away wood that is then transported to the mouth by cilia. Shipworms may also be filter-feeders of plankton, drawing in water through the incurrent siphon. Life History. Adult shipworms occur as separate males and females. Spawning apparently depends on temperature. It reportedly occurs from April to September in New Jersey and from May to October at Woods Hole, Massachusetts. Males release sperm into the water column. Other individuals take them in through their incurrent siphons, and fertilization

72 n INVERTEBRATES (MOLLUSKS) occurs internally in the chamber housing the gills. Larvae are brooded in the gills until the velum (a ciliated organ that provides locomotion) and a straight-hinged shell form. Then the larvae are released into the water column, where they begin a planktonic stage lasting up to four weeks. During this phase, they form siphons, gills, and an obvious foot. The tiny (0.04 in. or 1 mm) final-stage larvae detect wood chemically and swim toward it, attaching themselves with byssal threads. It is not known how the soft-shelled larvae bore into wood; maternal enzymes may aid in softening the surface. The settled larvae rapidly metamorphose into This peculiar bivalve has a long wormlike body and a tiny shell used to juvenile shipworms. They bebore into wood. (U.S. Geological Survey.) come sexually mature adults six weeks after settlement. Impacts. In the past, this animal was so abundant in harbors around the world that they determined the lifespan of a wooden ship. It was reported in Wales that submerged ship timbers were destroyed in eight years. The presence of shipworms necessitated covering ships’ hulls in tar or cladding them in copper. The outbreak in San Francisco Bay from 1919 to 1921 destroyed untold numbers of wharves, piers, and other waterfront structures. On average, a major structure was lost every two weeks with enormous economic consequences. In the Baltic Sea area, there is concern today that thousands of ancient shipwrecks lying on the seafloor and of great archeological value could be destroyed if naval shipworms invaded the sites. If and how this species affects native or other introduced shipworms has not been studied, but competition for food is possible. Management. The naval shipworm is less of a problem today than in the past as a result of many fewer wooden-hulled ships and the widespread use of chemically treated timbers in waterfront construction. However, in the absence of these defenses, it will still destroy wooden structures below water.

Selected References Masterson, J. “Teredo navalis.” Smithsonian Marine Station, 2007. http://www.sms.si.edu/irlSpec/ Teredo_navalis.htm. NIMPIS. “Teredo navalis Species Summary.” National Introduced Marine Pest Information System, edited by C. L. Hewitt, R. B. Martin, C. Sliwa, F. R. McEnnulty, N. E. Murphy, T. Jones, and S. Cooper, 2002. Available at http://www.frammandearter.se/0/2english/pdf/Teredo_navalis.pdf. “Shipworm (Teredo navalis).” Wreck Protect, n.d. http://wreckprotect.eu/fileadmin/site_upload/ wreck_protect/pdf/shipwormspdfnew.pdf.

NEW ZEALAND MUD SNAIL n 73

n New Zealand Mud Snail Also known as: Jenkin’s spire shell Scientific name: Potamopyrgus antipodarum Synonyms: Hydrobia jenkinsi, Potamopyrgus jenkinsi Family: Hydrobiidae Native Range. Freshwater streams and lakes and brackish habitats in New Zealand and adjacent islands. Distribution in the United States. Populations are found in all western states except New Mexico and in four of the Great Lakes: Ontario, Michigan Erie, Michigan and Superior. Description. This very small aquatic snail typically measures 0.25 in (4–5 mm) in the western United States, although it may be twice that large in its native range. The cone-shaped shell has right-handed coils and contains 5–6 whorls separated by deep indentation. A retractable plate (operculum) covers the oval opening to the shell and protects the animal when it retreats into its shell. Shell color ranges from gray to light or dark brown. Different morphs appear among introduced populations. Many from the Great Lakes and western states have a slight keel in the middle of each whorl, whereas others from the Great Lakes have spines on the whorls. One morph found in the West is wider than usual and so pale and transparent that internal structures are visible. Related or Similar Species. The New Zealand mud snail could be confused with a number of native snails in the western United States and may be confidently identified only by experts. The shell is longer and narrower than most native snails of the same family and has more whorls. No native western snails Top: The New Zealand mud snail is native to fresh and brackish water have keels. Most native species habitats in New Zealand. Bottom: New Zealand mud snails have have fewer whorls than the New invaded almost all western states and four of the Great Lakes. (Adapted Zealand land snail. (The Aquatic from Benson and Kipp 2009.)

74 n INVERTEBRATES (MOLLUSKS)

A. The retractable plate or operculum and deep indentations separating whorls are clearly visible on this common form of the New Zealand mud snail. B. Spines occur on the whorls of many individuals from the Great Lakes region. C. The living animal (D. L. Gustafson, Montana State University.)

Nuisance Species Research Program of the U.S. Army Corps of Engineers presents comparative photos of native snails at http://el.erdc.usace.army.mil/ansrp/potamopyrgus_antipodarum.pdf.) Introduction History. The exact means of introduction to U.S. waters is unknown, but the snails likely arrived with shipments of fish eggs and live game fish from New Zealand to some western states. Introduction to the Great Lakes, on the other hand, probably occurred with the discharge of ballast water by ships coming from Europe. First records of the snail came from the Snake River, Idaho, in 1987. Populations were reported near the mouth of the Columbia River in Oregon in 1997, and they were established in the lower Columbia in Washington by 2002. First reports from California come from the Owens

NEW ZEALAND MUD SNAIL n 75

River; it is now widespread in that state. In 2002, the snails were in the Colorado River in northern Arizona; in 2004, they were discovered in a small creek near Boulder, Colorado. An established population existed in Lake Ontario in 1991 and in Lake Erie by 2005. They were also found in Duluth harbor on Lake Superior in 2005. The tiny New Zealand mud snail may be inadvertently transferred from one body of water to another on boats, boots, waders, clothing, and other recreational gear. They may possibly be spread by animals, because they can pass unharmed through the guts of fish and birds. Even cattle wading in streams and ponds could transport these mollusks, since they are able to withstand desiccation for a short period time by withdrawing into their shells behind a closed operculum. Within a river or lake system, the snails may float downstream or become attached to floating mats of algae. They have also been shown to be capable of moving upstream under their own volition. Since most New Zealand mud snails reproduce asexually, it takes only one snail to begin a new population. They spread rapidly and now have access to the eastern United States via the Great Lakes. Habitat. The New Zealand mud snail is found in a variety of freshwater and brackishwater habitats at depths up to 150 ft. (45 m). It inhabits streams, lakes, estuaries, lagoons, canals, ditches, and water tanks on just about any type of substrate, from mud and sand to concrete and within many types of vegetation. It prefers the littoral zone of lakes and slowmoving streams, but because it can burrow into sediments. It tolerates fast-moving water. These snails thrive in salinities of 0–15 ppt and for short periods of time will tolerate salinities near that of seawater. They also tolerate a wide range of temperatures from 32° to 110°F (0–34°C). They are preadapted to live in degraded water systems with high nutrient content and/or heavy siltation. Diet. This small gastropod is a scraper/grazer that feeds nocturnally on plant and animal detritus and on living algae and other organisms attached to the substrate (the periphyton). Diatoms are prominent in its diet. Life History. Most New Zealand mud snails in the United States are members of all female populations, meaning that individuals in a population are clones and genetically identical. Males are not needed for reproduction; indeed, the female is born with 20–120 developing embryos already in her reproductive system. Sexual reproduction does occur, but sexual males and females are very rare. Females generally release live young in summer and autumn. Average lifespan is about one year. Sexual males and females are mature when about 0.1 in. (3 mm) in size. New Zealand mud snails have a high reproductive potential and it is not unusual for population densities to exceed 5,290/ft.2 (100,000/m2). In the Madison River near Yellowstone National Park in Montana, densities three times greater are reported. Impacts. The New Zealand mud snail has had negative impacts in other parts of the world and is expected to have them in the United States as well. Concerns center on its potential to decrease populations of native herbivorous invertebrates—including native snails—through competition for food and space and to reduce the periphyton cover that serves as nourishment and substrate for some aquatic organisms. Evidence from Montana suggests a decrease in larval mayflies, stoneflies, caddisflies, and black flies when the snails become abundant. These insects are important food for native trout and other fish, and their loss could negatively impact the important recreational fishing industry in many western states. In the Snake River, Idaho, five native mollusks (Utah valvata snail [Valvata utahensis], Idaho springsnail [Pyrgulopsis idahoensis], Snake River physa [Haitia natricina], Banbury

76 n INVERTEBRATES (MOLLUSKS) Springs lanx [Lanx sp.], and Bliss Rapids snail [Taylorconcha serpenticola]) are listed as threatened or endangered, possibly as a consequence of competition from New Zealand mud snails. A decrease in the periphyton would alter the physical environment and affect ecosystem processes beginning with primary production. Very dense populations of the mud snails could clog intake filters at facilities withdrawing lake or river water. Management. Little can be done to eradicate established populations of the New Zealand mud snail. Management is focused on the prevention of its spread to additional bodies of water. Boats and fishing and other gear should be scrubbed before leaving an infested body of water and thoroughly dried for at least 24 hours or treated with heat ( > 85°F [30°C]) before being used elsewhere.

Selected References Benson, A. J., and R. M. Kipp. “Potamopyrgus antipodarum.” Nonindigenous Aquatic Species Fact Sheet, U.S. Geological Survey, 2009. http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=1008. Crosier, Dani, and Dan Malloy. “New Zealand Mudsnail (Potamopyrgus antipodarum).” United States Federal Aquatic Nuisance Species Task Force, 2005. http://www.anstaskforce.gov/spoc/nzms.php. Crosier, Danielle, and Daniel P. Molloy. “New Zealand Mudsnail–Potamopyrgus antipodarum.” Aquatic Nuisance Species Research Program, U.S. Army Corps of Engineers, n.d. http://el.erdc.usace .army.mil/ansrp/potamopyrgus_antipodarum.pdf. Richards, David C., Billie L. Kerans, and Daniel L. Gustafson. “New Zealand Mudsnail in the Western USA.” Montana State University-Bozeman, 2004. http://www.esg.montana.edu/aim/mollusca/nzms/.

n Quagga Mussel Scientific name: Dreissena rostriformis bugensis Family: Dreissenidae Native Range. Dnieper and Bug rivers and Dnieper-Bug Estuary, Ukraine. Distribution in the United States. Established in all of the Great Lakes. Also found in inland bodies of water in Arizona, California, Colorado, Illinois, Iowa, Kentucky, Michigan, Minnesota, Missouri, Nevada, New York, Ohio, and Pennsylvania. Description. The quagga mussel is a small freshwater bivalve with asymmetrical valves and a convex ventral side that prevents it from maintaining a stable upright position. The byssal groove on the ventral side is small and positioned near the hinge, and the angle between the ventral and dorsal surfaces is rounded. There are usually dark concentric bands on the shell that fade near the hinge, but shell patterns are quite variable and the bands may be black, cream, or white. In Lake Erie is a type that is completely white. Two distinct forms are found in the Great Lakes. One type, the so-called “epilimnetic” or shallow water form, has a high flat shell; the other, the “profunda” or deep, cold-water form, has a somewhat elongated, globular shape. The epilimnetic type attaches to hard surfaces with hairlike byssal threads and forms dense colonies or druses; they may attach to the shells of other quagga mussels and create mats 4–12 in. (10–30 cm) thick that encrust or clog pipes and other manmade features. The profunda type, while it can attach to objects with byssal threads, may also partially bury itself in soft sediments and extend a long incurrent siphon above its shell to draw in suspended organic matter. Quagga mussel shells grow to lengths of about 1.5 in. (4 cm). Related or Similar Species. Quagga mussels are quite similar to the closely related zebra mussel (Dreissena polymorpha; see Mollusks, Zebra Mussel). In fact, the two were not immediately identified as separate species. The quagga mussel shell has a convex ventral side

QUAGGA MUSSEL n 77

in contrast to the flat or convex ventral side of zebra mussels. The quagga mussel shell is rounded, whereas that of the zebra mussel is more triangular. The zebra mussel also is distinct by virtue of bilateral symmetry along a midventral line and a long byssal groove in the middle of the ventral side. The Asian clam (Corbicula fluminea), another small invasive bivalve (see Mollusks, Asian Clam), lacks byssal threads and has a thicker, ridged shell. It is light-yellowish brown to dark brown and usually is not striped. Introduction History. The first known occurrence of quagga mussels in the Great Lakes dates to September 1989, although at the time the collected specimen was believed to be a form of zebra mussel. The specimen was obtained near Port Colburne, Lake Erie. In 1991, a mussel taken from the Erie Canal was positively identified as a new species and dubbed the quagga mussel after a less-striped relative of the Plains zebra that is now extinct. Top: Quagga mussels are native to the Dnieper and Bug rivers and estuary The mussel was most likely in Ukraine. Bottom: Quagga mussels are established in all of the Great introduced in discharged ballast Lakes and in many inland bodies of water across the lower 48 states. water from transoceanic freight- (Adapted from Benson, Richerson, and Maynard 2010.) ers. The mussel spread through the lower Great Lakes and reached Duluth Harbor, Lake Superior, by 2005. Quagga mussels were discovered in the Mississippi River between St. Louis, Missouri, and Alton, Illinois, in 1995. Larvae can float downstream in rivers or on currents in lakes. They can leapfrog from lake to lake attached to boats and boat trailers or in anything that holds water. Adults are able to withstand exposure to air for 3–5 days. In January 2007, quagga mussels showed up in the major impoundments on the Colorado River, first in Lake Mead, near Boulder City, Nevada, and then in Lakes Mohave and Havasu along the lower Colorado River. The same year, they entered the Colorado River Aqueduct, which diverts water from the Colorado River to southern California. Since then, they have been found in 15 reservoirs in southern California and also in six reservoirs in the state of Colorado. They are also in the Nevada State Fish Hatchery on Lake Mead and at Willow Beach National Fish Hatchery, just downstream from Hoover Dam on the

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A. Quagga mussel shells are asymmetrical; pattern and color vary. (U.S. Geological Survey.) B. The living animal. (M. Quigley, GLERL.)

Colorado, which raises trout and threatened native fishes to stock Lakes Mead and Mohave and to restock the Colorado River. Habitat. Quagga mussels are found in the upper reaches of estuaries, in lakes and reservoirs and connecting waterways. They do best in freshwater with salinities less than 1 ppt, but can still reproduce in brackish water with salinities near 3 ppt. (They die in salinities greater than 6 ppt). Quaggas apparently have a broader range of temperature tolerance than zebra mussels and hence inhabit a wider range of water depths. As a consequence they occupy both shallow warm waters and deeper cold-water habitats. In North America they are colonizing waters where the temperature remains between 39° and 48°F (4–9°C) all year. Adults attach to natural hard surfaces of rock, shell, and wood or to large aquatic plants as well as to manmade structures of concrete, metal, nylon, fiberglass, and wood. Some morphs also bury themselves in soft lake bottoms. Diet. Filter-feeders, quagga mussels ingest food particles by pulling water into the shell cavity with cilia. The water passes into an incurrent siphon where phytoplankters, zooplankters, and other suspended organic matter are extracted. Indigestible particles are cemented together with mucus and ejected from the incurrent siphon as pseudofeces; water is discharged from an excurrent siphon. Life History. Individuals are either male or female and reproduce externally when eggs and sperm are released into the water column. Microscopic embryos develop into larvae in a few days. The larvae soon sport tiny bivalve shells and drift as part of the plankton for 3–4 weeks. When suitable substrates are found, juveniles settle and attach themselves with byssal threads. Adults are also sessile, but able to detach and move to new sites. Spawning usually peaks in spring and autumn in the Great Lakes, but elsewhere may occur throughout the year. In Lake Havasu on the Colorado River, quaggas reportedly spawn six times a year. The average lifespan is five years. Impacts. Major alteration of aquatic ecosystems can result from heavy infestations of quagga mussels. Their removal of much of the phytoplankton and other suspended organic matter from the water column reduces the food supply of zooplankters and thereby affects the rest of the food chain. Their production of large amounts of pseudofeces transfers much of the energy in the system from the upper parts of the water column to benthic habitats. Bottom-feeding fish increase at the expense of plankton-feeders. In addition, when large accumulations of pseudofeces decompose, oxygen is withdrawn from the water. In the central basin of Lake Erie, dead zones of oxygen-depleted water have appeared for decades in late summer at depths greater than 40 ft. (12 m). Even with the general amelioration of severe nutrient pollution problems that affected the lake in the 1970s, these dead zones

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persist. One hypothesis is that changes in nutrient cycles brought on by the introduction of quagga and zebra mussels may be a cause. The reduction of planktonic green algae increases water clarity and allows greater growth of macrophytes in shallow waters, changing the species composition of the plant community and the physical structure of the aquatic environment as well as available food sources. Emergent and floating plants become nursery areas for a variety of aquatic organisms. Indications are that quagga mussels outcompete their close relative the zebra mussel and are replacing them in shallow waters. They also foul native mollusks and other hard-shelled invertebrates, but their presence in American waters is too brief for any impacts to be realized. Mussels bioaccumulate pollutants in the water. These pollutants collect in pseudofeces and from there can pass up the food chains to game fish and other wildlife. The bivalves themselves are consumed by some crayfish, fish, and diving ducks, offering another pathway for concentrated toxins to move into food chains. Quagga mussels biofoul organisms and clog the pipes and screens of water intake structures. This can reduce pumping capacity and damage equipment and cost industries and communities millions of dollars to mitigate. Fouling of water-intake screens and sluice gates has rapidly become a major problem along the Colorado River, which supplies drinking and irrigation water via long aqueducts to the major cities and agricultural regions of southern California, southern Nevada, and southern Arizona. Management. A variety of control methods are available, but so far none has proved both effective and environmentally sound. Biological controls that would target quagga (and zebra) mussels and interrupt their reproductive cycle or interfere with the settling of the larvae are being researched.

Selected References Benson, A. J., M. M. Richerson, and E. Maynard. “Dreissena rostriformis bugensis.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2008. http://nas.er.usgs.gov/queries/FactSheet.asp ?speciesID=95. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Dreissena bugensis (Mollusc).” ISSG Global Invasive Species Database, 2006. http:// www.issg.org/database/species/ecology.asp?si=918&fr=1&sts=sss. Richerson, Myriah. “Dreissena species FAQs, a closer look.” USGS, 2009. http://fl.biology.usgs.gov/ Nonindigenous_Species/Zebra_mussel_FAQs/Dreissena_FAQs/dreissena_faqs.html.

n Veined Rapa Whelk Also known as: Asian rapa whelk Scientific name: Rapana venosa Synonym: Rapana thomasiana Family: Muricidae Native Range. Estuarine and marine waters of the western Pacific Ocean. It is known from Vladivostok, Russia, south to Taiwan in the Sea of Japan, the Yellow Sea, the Bohai Sea, and the East China Sea. Genetic studies of whelks from the Chesapeake Bay suggest they arrived in American waters via the Black Sea, to which they were introduced in the 1940s.

80 n INVERTEBRATES (MOLLUSKS) Distribution in the United States. Established in Chesapeake Bay from the mouth of the Rappahannock River south to the bay’s entrance. Based on water temperatures similar to that of their native distribution area, and the existence of a high volume of coastwise trade out of Hampton Roads, their potential range extends from Cape Cod, Massachusetts, to Charleston, South Carolina. Description. This large marine snail is most readily identified by the bright orange color of the inside of its shell, visible at the large, oval aperture that opens on the right side of the shell. The heavy shell is globular in shape and has a short spire, broad flat columella, and deep umbilicus (the hollow on the ventral side). Smooth spiral ribs terminate in blunt knobs adorning the shoulder, and the edge of the outer lip is finely toothed. The outer shell ranges from gray to brown and bears dark brown lines that create an interrupted pattern over the entire shell. Top: The veined rapa whelk is native to estuarine and marine waters from Dark veining may occur on the southeastern Russia to Taiwan. Bottom: Veined rapa whelks have been inside of the shell. In their native found in the Chesapeake Bay. (Adapted from International Council for range, they reach a length of 7 in. the Exploration of the Sea 2004.) (180 mm). Adults slightly over 6.5 in. (170 mm) have been collected in the Chesapeake Bay. The egg cases of the veined rapa whelk are also distinctive, usually described as resembling a yellow shag rug. They are about 1.2 in. (30 mm) high and individually attached to the seafloor to form a mat. Related or Similar Species. Two large native whelks inhabit the potential range of the veined rapa whelk along the East Coast of the United States. Neither the knobbed whelk (Busycon carica) nor the channeled whelk (Busycon canliculatum) has a broad flat columella or the dark veining on the shell. Both native whelks are more elongated, have thinner shells, and display less ribbing on the outside of their shells than does the veined rapa whelk. Egg cases of the knobbed whelk are strung together in a long chain, a “mermaid’s necklace.” Introduction History. The first scientific evidence of veined rapa whelks in Chesapeake Bay came in 1998, when researchers from the Virginia Institute of Marine Science collected

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a specimen in Hampton Roads, Virginia. The large whelk was probably 10 years old, strongly suggesting the presence of whelks in the bay since 1988, a fact confirmed anecdotally by local watermen. The species likely arrived in ballast waters in empty coal vessels returning from the eastern Mediterranean, since Norfolk, Virginia, is a major coal-exporting port. Genetic studies support this contention. The long larval period when the whelk floats in the water column facilitates the long distance dispersal of this gastropod by currents Adult veined rapa whelks found in the Chesapeake Bay have reached just in the bay and by container over 6.5 in. long. Larger specimens occur in their native range. (George Chernilevsky.) ships and other vessels that take up ballast water before heading to ports all along the East Coast. Habitat. Subtidal zones of coasts and estuaries. Adults prefer sandy bottoms into which they burrow, but juveniles tend to dwell on hard substrates, including oyster reefs, and only migrate to areas with sandy bottoms when shell length is about 2.75 in. (70 mm). In its native range, it tolerates a wide annual range of temperatures, from 39–80ºF (4–27ºC); in cooler climates, it may migrate to deeper and warmer water during winter. Adults and larvae can withstand low salinities and polluted and/or oxygen-poor water. Diet. Larvae consume phytoplankters, but juveniles and adults are carnivores. Prey includes other shellfish that live in soft sediments (the infauna), such as clams and mussels, and oysters. Most vulnerable in the Chesapeake Bay are native hard clams (Mercenaria mercenaria), but mussels (Mytilus edulis), soft-shell clams (Mya arenaria), and oysters (Crassostrea virginica) are also taken. The whelk engulfs its prey whole; and, when the bivalve opens, it sucks out the soft body of the victim, leaving behind a clean shell with few telltale scars. Life History. In its native range, mating occurs during winter and spring, and eggs are laid from April to late July. Each egg case is attached by its base to a hard substrate. From 200 to 1,000 eggs are contained in each case; each mat may consist of 50- to 500-egg cases. A female can lay several mats a year from a single mating. Initially, the egg cases are white, but as the larvae become visible swimming inside, they turn yellow. After an incubation period of 14–17 days (depending upon temperature), the egg cases blacken, open, and the larvae swim free out of the top of the case to become part of the plankton. The larval stage lasts for a variable length of time, extending as long as 80 days. Upon metamorphosis, they settle onto attached invertebrates such as bryozoans and barnacles and become tiny, hardshelled, cryptically colored whelks. The young whelks grow quickly so that within three weeks, their shell’s length approaches 0.02 in. (0.5 mm); within a year, they are more than 2.4 in. (60 mm) long. Veined rapa whelks begin to reproduce at two years of age, when they have a shell length of about 3 in. (74 mm). The largest whelks collected from the Chesapeake Bay are estimated to be about 10 years old.

82 n INVERTEBRATES (MOLLUSKS) Impacts. The veined rapa whelk has a history of negative impacts in European waters, especially in the Black Sea, where its predation was implicated in the rapid decline of native edible bivalves and near extinction of oysters (Ostraea edulis) on the Guadata oyster bank. Concern is therefore high that similar impacts could ensue at commercially important fisheries in the Chesapeake Bay and elsewhere along the East Coast of the United States. In the Chesapeake Bay, it appears that hard clams are most threatened, since oysters are confined by disease to very low-salinity sites. These nonnative whelks might compete with the native oyster drill (Urosalpinx cinerea), a species struggling to recover from a massive die-off caused by an influx of freshwater related to Hurricane Agnes in 1972. A shift in relative abundance of hermit crab species is also possible. The shells of the veined rapa whelk are well suited to house the striped hermit crab (Clibanarius vittatus), but less so to the currently dominant flat-clawed hermit crab (Pagurus pollicaris). The former is predator of oysters, and its increase would add to pressures already affecting the bay’s remaining oyster populations. Management. It appears unlikely that established populations can be eradicated, so the emphasis of research is on identifying sites vulnerable to invasion and trying to prevent the organism’s spread. Several states on both coasts of North America have issued alerts for their citizens to be on the lookout for veined rapa whelks and report any sightings to authorities. For a time, researchers on Chesapeake Bay offered a bounty on whelks caught by fishermen, in part to monitor the status and spread of the whelk population and in part to discourage fishermen from throwing the by-catch back into the water.

Selected References Chesapeake Bay Introduced Species Database. “Rapana venosa.” NEMESIS (National Exotic Marine and Estuarine Species Information System). Smithsonian Environmental Research Center, 2009. http:// invasions.si.edu/nemesis/CH-TAX.jsp?Species_name=Rapana%20venosa. International Council for the Exploration of the Sea. “Alien Species Alert: Rapana venosa (Veined Whelk),” edited by Roger Mann, Anna Occhipinti, and Juliana M. Harding. ICES Cooperative Research Report No. 264, p. 14, 2004. http://www.ices.dk/pubs/crr/crr264/crr264.pdf. Richerson, Myriah. “Rapana venosa.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2006. http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=1018. Southeast Ecological Center. “Veined Rapa Whelk, Asian Rapa Whelk, Rapana venosa (Valenciennes, 1846) Mollusca: Gastropoda, Muricidae.” Nonindigenous Species Information Bulletin, U.S. Geological Survey, 2009. http://fl.biology.usgs.gov/Nonindigenous_Species/Rapa_whelk/rapa _whelk.html.

n Zebra Mussel Scientific name: Dreissena polymorpha Family: Dreissenidae Native Range. Eastern Europe and western Asia in the drainage systems of the Black and Caspian seas and the Sea of Azov. U.S. populations originate from mussels transported from the southern limit of their range. Distribution in the United States. Zebra mussels are now found in waterways in or bordering at least 30 states in the continental United States. They are established in all of the Great Lakes and in most navigable drainages in the Mississippi River system, including the Missouri River in Nebraska and South Dakota. They are also established in the Hudson

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River and found in numerous inland lakes in the Midwest. The most recent introductions have occurred in San Justo Reservoir in central California, two reservoirs in Colorado, Lake Texoma on the TexasOklahoma border, and a lake in western Massachusetts. Description. Zebra mussels are small freshwater bivalves with triangular shells. The bottom of the shell where the hinge lies is flat or concave, and the shell margin is sharply angled. When placed upright on a flat surface, they are stable. Many bear dark stripes on the shell, but this pattern can be quite variable and even absent. Some will be plain and creamcolored; others black. Filaments or byssal threads extend from the bottom of the shell and bind them to each other or to hard surfaces. Usually zebra mussels occur in dense clusters or colonies known as druses. Shells of adults generally range in length from 0.2–1.8 in. (6–45 mm), with a maximum length of about 1.9 in. (0.5 cm). Top: Zebra mussels are native to the drainage systems of the Black, Azov, Related or Similar Species. and Caspian seas. Bottom: Zebra mussels are a scourge in at least 30 states Two other dreissenids occur in and are established in all the Great Lakes and much of the Mississippi North America, the native false River system. (Adapted from Benson and Raikow 2009.) dark mussel (Mytilopsis leaucophaeata) and the introduced quagga mussel (Dreissena rostriformis bugensis; see Mollusks, Quagga Mussel). Each has a convex bottom edge and a rounded shell margin, which prevents it from balancing in an upright position. Introduction History. The introduction of zebra mussels probably stems from a single exchange of ballast water by a commercial ship entering the Great Lakes from the northern Black Sea. The first reports came from Lake St. Clair, which connects Lake Erie and Lake Huron, in 1988. It is likely they had been in the lake for 2–3 years before having been detected. By 1990, the passive drifting of larval mussels and the ability of juveniles and adults to attach to barges and other vessels had allowed them to disperse into all the Great Lakes. In 1991, they were in the Illinois River, gateway to the Mississippi River, and within a year they were established in the Arkansas, Cumberland, Ohio, and Tennessee rivers. They were also in the Hudson River and the Finger Lakes of New York by 1991. Overland

84 n INVERTEBRATES (MOLLUSKS)

A. Zebra mussels overgrow the shells of native mollusks. (Eric Engbretson.) B. A living zebra mussel is in a stable position when placed upright on its hinge. (M. Quigley, GLERL.) C. The dense clusters in which zebra mussels usually congregate are called druses. (Eric Engbretson.) D. Some of the variation found in shell patterns of Dreissena polymorpha. (U.S. Geological Survey.)

dispersal has undoubtedly been facilitated by recreational boaters trailering their watercraft from infested bodies of water to pristine waters without decontaminating hulls, trailers, livewells, and engines. Zebra mussels were first recorded in Virginia in a quarry pond in 2002. Other states with first records in the twenty-first century include Kansas (Perry Lake and the Kansas River) in 2007; California (San Justo Reservoir, San Benito County) and Colorado (Pueblo Reservoir—an impoundment on the upper Arkansas River near Pueblo and four reservoirs west of Denver) in 2008; and Texas and Oklahoma (Lake Texoma), and Massachusetts (Laurel Lake, Berkshire County) in 2009. Habitat. Zebra mussels can be found in freshwater lakes, ponds, and rivers. Usually they occur in shallow, algae-rich water at depths of 6–30 ft. (2–9 m). They require hard substrates for settling and attachment. They thus may occur on rocks; in and on metal, concrete, or other manmade structures; on the shells of other mollusks and the exoskeletons of

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crustaceans; and even on the cases of caddisfly larvae. In soft sediments, they may attach to pieces of shell or wood and other plant material or to stones and still be able to establish a druse. Adults do not survive freezing temperatures and die when water temperatures are above 75°F (24°C) for extended periods of time. They also do poorly in oxygen-poor waters. Optimal calcium-ion concentrations for zebra mussels are 45–55 mg/l, and optimal pH for adult growth lies between 7.4 and 8.0. Diet. Larval, juvenile, and adult zebra mussels are filter-feeders, capturing primarily algae and zooplankters in the water column. They also feed on bacteria and detritus. Life History. Female mussels release eggs into the water column, where they are fertilized by sperm released by males. Most spawning occurs between June and September, when water temperatures are at an optimal 54–68°F (12–20°C). Three distinct periods characterize the life cycle of the zebra mussel. The microscopic larvae are part of the plankton and undergo four stages when they are essentially clam-like in shape. In the final larval stage, a larva settles on a substrate and crawls to a suitable attachment site. There it undergoes metamorphosis and begins its juvenile period with a small (1–3 mm), triangular shell. Gametes become fully developed juveniles in 8–180 days; the colder the water, the slower the development time. The adult period starts when the mussel becomes sexually mature, usually at one year of age and a shell length of 0.3–0.35 in. (8–9 mm). A zebra mussel lives on average 2–3 years after attachment. Impacts. Dense populations of zebra mussels have the potential to alter freshwater ecosystems and change the physical environment by eliminating or reducing the numbers of native organisms. The great filtering capacity of these small mussels reduces the phytoplankton and increases water clarity. This allows large, rooted aquatic plants to increase and changes not only the food supply, but the physical structure of the system. In some instances, the sessile juveniles and adults even outcompete zebra mussel larvae, which rely upon phytoplankters for nourishment. A diminished supply of phytoplankters such as diatoms leads to a reduction in the zooplankters upon which many fishes depend. Larval stages of fish such as the bluegill (Lepomis macrochirus) in inland lakes may be strongly affected. At the same time, the prodigious amount of feces and pseudofeces produced in large druses increases the food supply for macroinvertebrate bottom feeders and thus for fish that feed on these animals. Bacterial productivity also increases to break down the mussels’ wastes, which may increase food available to the mussels themselves. Zebra mussels are eaten by native mollusk-eating fish such as freshwater drum (Aplodinotus grunniens), lake sturgeon, yellow perch, and catfish, which have been shown to increase in heavily infested waters. Thus, a change in the composition of the fish community occurs as benthic-feeding fish replace planktivorous species.

Zebra Mussels

T

he invasion of zebra mussels in the 1980s sparked new interest in the problems associated with exotic species. The new science of invasion biology developed within the discipline of ecology, the Nonindigenous Aquatic Nuisance Prevention and Control Act was passed, and public perception of the threats posed by introduced species to both aquatic and terrestrial ecosystems grew. Invasions became a common topic in the media and increasingly a subject of scientific research. For some, the zebra mussel is the “poster child” of biological invasions.

86 n INVERTEBRATES (CRUSTACEANS) The attachment of zebra mussels to the shells of native clams (unionids) makes it more difficult for the clams to move through sediments in search of food and optimal concentrations of oxygen. In contrast, encrusted bivalves in wave-impacted areas are easily dislodged and washed away from prime sites. Furthermore, mussels can obstruct the openings of the clams’ shells and prevent food intake and the release of gametes or prevent defensive closing of the shell. During the very early invasion of Lake Erie, reports came of thousands of zebra mussels on a single unionid. Native clam populations in the western basin of Lake Erie and in Lake St. Clair have plummeted. The zebra mussel is the most serious biofouling organism to have been introduced into American waters. It clogs water intake and distribution pipes in industrial and power plants that withdraw water from lakes and rivers, increases the corrosion rates of iron and steel pipes and rivets, and obstructs pumps, valves, weep holes, screens, and the like, damaging equipment and entire facilities. After storms on the Great Lakes huge windrows of mussel shells accumulate on beaches; the decaying mollusks release methane and produce a noxious stench. The razor-sharp shells are hazards to beachgoers. Management. Control of zebra mussels is problematic. Chemical molluscicides; manual removal; ultraviolet, hot water, and CO2 treatments; filters; screens; and electrical currents all have been tried. Preventing their spread into new waterways is the target of most management schemes. This can be best achieved through the decontamination of diving and fishing gear and of boats and boat trailers, and stopping the dumping of unused bait in lakes and rivers.

Selected References Benson, A. J., and D. Raikow. “Dreissena polymorpha.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2009. http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=5. Nichols, S. Gerrine. “Zebra Mussel Identification.” Zebra Mussel Research Program. Zebra Mussel Information System, Environmental Laboratory, Engineer Research and Development Center, United States Army Corps of Engineers, 2002. http://el.erdc.usace.army.mil/zebra/zmis/zmishelp4/ zebra_mussel_identification.htm.

n Crustaceans n Chinese Mitten Crab Scientific name: Eriocheir sinensis Family: Varunidae (formerly Grapsidae) Native Range. Subtropical East Asia, from Fukien Province, China, north to the Korean Peninsula. Distribution in the United States. The Chinese mitten crab is established only in California, where it occurs in the Sacramento-San Joaquin Delta and tributary streams. Specimens have been collected in Delaware, Louisiana, Maryland, New York, Ohio, and Washington. Until 2007, all those collected outside of California were males; but recently females with eggs have appeared in the Mid-Atlantic states, so breeding populations may now exist there. Description. The Chinese mitten crab is most easily identified by the character that gives it its name: light brown, hairy claws of equal size that have white tips and make it look like

CHINESE MITTEN CRAB n 87

the animal is wearing mittens. The brown hairs (setae) are evident in juveniles when the carapace is about an inch (25 mm) wide. The carapace is round in outline and convex, but bumpy on the dorsal surface. There is a distinct notch between the eyes. On the edges of the front part of the carapace are four spines, the fourth of which is quite small. Females have a wide abdominal flap shaped like a beehive; males have a narrow, bell-shaped abdominal flap. These differences are apparent in animals larger than 0.4 in. (10 mm). The legs are more than twice as long as the carapace is wide. The crab is brownish orange to greenish brown in color. Carapaces of adults are 1.2–4.0 in. (30–100 mm) wide. In California, adults reach about 3 in. (80 mm). Juvenile Chinese mitten crabs will dig burrows into vertical, clay river banks within the intertidal zone. The burrows have oval openings and may be 1–3 in. (2.5–7.6 cm) wide and as much as 8 in. (20 cm) deep. Top: The Chinese mitten crab is native to subtropical regions of east Asia. They slope downward and may Bottom: The Chinese mitten crab is invasive only in California, although have two entrances. individuals have been collected elsewhere. Females with eggs have been Related or Similar Species. reported from Mid-Atlantic states, suggesting populations may be becomThe Harris mud crab (Rhithro- ing established there. (Adapted from Benson and Fuller 2007.) panopeus harrisii), similar in size and general appearance and native to the Atlantic coast of North America, could be mistaken for a young Chinese mitten crab. However, it lacks the hairy claws and the notch between the eyes and is most commonly found in estuaries. The Harris mud crab has ridges on the back of the carapace, which is brown or black. Maximum carapace size is 0.75 in. (19 mm). The entrances to its burrows are circular and about 1.5 in. (38 mm) wide. Occasionally, the very similar Japanese mitten crab (Eriocheir japonicus) is reported in the United States, but this species is not widely established outside its native range. (Some scientists think it is the same species as the Chinese mitten crab.) The Chinese mitten crab is the only crab found in freshwater in the United States. Its carapace shape differs from all other true crabs that occur here.

88 n INVERTEBRATES (CRUSTACEANS) Introduction History. A single Chinese mitten crab was taken by a shrimp trawler in South San Francisco Bay in 1992. They were captured in San Pablo Bay in 1994, Suisun Marsh in 1996, and the Delta in the fall of 1996. Several dozen were trapped upstream at the U.S. Bureau of Reclamation’s Tracy Fish Collection Facility at the Delta Mendota canal in 1996. Migrating crabs in the fall of 1997 numbered in the tens of thousands; and the following year, the population Chinese mitten crabs get their name from their hairy claws. (© N. Sloth/ was estimated to be 775,000 Biopix.) and threatened to shut down fish salvage operations at the canal pump station. By 2000, Chinese mitten crabs were reported 30 mi. (50 km) upstream from the Bay-Delta, with no halt to their expansion expected. It is likely that this popular Asian delicacy was deliberately introduced as live crabs for human consumption or to develop a local food resource, although the release of untreated ballast water could also disperse these animals. Specimens collected in other parts of the United States suggest that the illegal import and release of live crabs continues, although so far, populations have not become established outside of California. The crab was found in Hawai’i in the 1950s; and Chinese mitten crabs have been reported from the mouth of the Columbia River, Washington, from Yaquina Bay in central Oregon, and from the Great Lakes region since the 1960s. More recently they have shown up in Chesapeake Bay (2005–2007), Delaware Bay (2007), the Hudson River in New York, (2007–2009), and the Shrewsbury River in New Jersey (2008–2009) on the East Coast of the United States. Only in New York have both male and female adult and juvenile crabs been collected. Live crabs have not been detected in Chesapeake and Delaware bays since 2007. Habitat. The Chinese mitten crab is catadromous and spends most of its life cycle in freshwater. Juvenile and adult crabs are also able to walk on dry land. Adults live in the bottoms and banks of freshwater streams, but they reproduce in the brackish water of estuaries. Late larval stages float in the upper part of the water column and are transported by currents toward the mouths of estuaries. Settling and metamorphosis into juveniles occurs on the seafloor along coasts and in embayments. A temperate-zone species, it is adapted to changing water temperatures and salinities and thus tolerates pollution. Optimal temperatures are 75–82°F (24–28°C) for juveniles, 59–64°F (15–18°C) for larvae. Larvae in early stages of development tolerate a wide range of salinities. Diet. Usually described as opportunistic omnivores, Chinese mitten crabs consume algae, macrophytes, detritus originating on land, and invertebrates. They scavenge dead fish and are notorious for stealing fishermen’s bait. Life History. In San Francisco Bay, Chinese mitten crabs mate in the late fall and winter when water salinity is greater than 20 ppt. Some 24 hours later, a female spawns eggs, which

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are affixed underneath her abdominal flap. A female will carry 250,000 to one million eggs through the winter until they hatch in the spring or summer. Hatchlings become part of the plankton for 1–2 months. They settle in salt or brackish water in late spring or early summer, and the juveniles migrate to freshwater, perhaps aided by tidal currents. When living in tidal freshwater rivers, the juveniles congregate in dense colonies and burrow into the bank for protection against predators and desiccation at low tide. In nontidal areas, they apparently do not burrow. Older juveniles occur farther upstream than younger ones. While migrating upstream, crabs will leave the water and walk across banks and levees to bypass dams and other obstacles. When 1–4 years old, the males and females migrate downstream in late summer or fall to brackish water, where they become sexually mature. The males arrive first; mating begins as soon as the females arrive. Adults die soon after mating. Impacts. In the San Francisco estuary, Chinese mitten crabs may compete for food and shelter with such commercially important species as the red swamp crayfish (Procambarus clarkia) and the signal crayfish (Pacifasticus leniusculus). However, it is primarily a nuisance species for shrimp trawlers and both commercial and recreational fishermen, stealing bait, tearing nets, getting entangled in gear, and eating the catch. During downstream migrations, the large numbers of crabs involved will clog water intakes, reducing water flow and potentially causing power plant systems to overheat. The burrowing of juveniles can accelerate river bank and levee erosion and collapse. Chinese mitten crabs are intermediate hosts of a mammalian lung fluke (Paragonimus spp.) that could affect humans. However, neither the parasite nor its primary hosts, Asian freshwater snails, have been found in the United States. In China, the mitten crab is an agricultural pest in rice paddies, eating young shoots and damaging levees. There is concern that should the crab become established in the ricegrowing areas of the Gulf coast, it could have similar negative impacts. Management. In Germany, where these crabs have become a major problem, some success in controlling them has been achieved with traps on the upstream side of dams capturing juveniles during their upstream migration. Similarly, the use of traveling screens and trash racks at water intakes can capture large numbers of migrating crabs. Periodic backflushing can remove crabs from water intakes.

Selected References Benson, A. J., and P. L. Fuller. “Eriocheir sinensis.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2010. Revised July 20, 2007. http://nas.er.usgs.gov/queries/FactSheet.aspx ?speciesID=182. “Chinese Mitten Crab.” ProjectUFO, 2009. http://www.projectufo.ca/drupal/Chinese_Mitten_Crab. Chinese Mitten Crab Survey Program. “Chinese Mitten Crab Update, U.S. Atlantic Coast Bays and Rivers.” Smithsonian Environmental Research Center, 2009. http://www.serc.si.edu/labs/marine_ invasions/news/CHINESE_MITTEN_CRAB_UPDATE_APR21_09.pdf. Chinese Mitten Crab Working Group. “National Management Plan for the Genus Eriocheir (Mitten Crabs).” Aquatic Nuisance Species Task Force, 2003. http://www.anstaskforce.gov/Species %20plans/national%20mgmt%20plan%20for%20mitten%20crab.pdf. “Life History and Background Information on the Chinese Mitten Crab.” California Department of Fish and Game, 1998. http://www.dfg.ca.gov/delta/mittencrab/life_hist.asp.

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n Green Crab Also known as: European green crab, European shore crab Scientific name: Carcinus maenas Family: Portunidae Native Range. The green crab is native to the western Baltic Sea and the Atlantic coasts of northwest Europe and North Africa from Iceland and Norway to Great Britain and south along Spain and Portugal to Morocco and northernmost Mauritania. Distribution in the United States. On the Pacific coast, the green crab is established in most bays and estuaries from Monterey Bay, California, north to Grays Harbor, Washington. Populations, however, have remained small. Along the Atlantic seaboard, green crabs are established along the coast of New England. They are found south along the Atlantic coasts of Maryland and Virginia, but have not been collected in Chesapeake Bay. A single green crab was collected in Hawai’i in 1973. Description. The green crab has a somewhat hexagonal carapace. Five “teeth” or blunt spines edge the carapace behind each eye. Three bumps or rounded teeth lie between the eyes. The carapace has a granular texture and is usually a mottled dark green or brown with white or yellowish spots. The carapace is broader than it is long; its width is 2.4–3.9 in. (6–10 cm). The ventral surface varies in color from green to yellow, orange, or red, depending on molt status. The second and third pairs of walking legs are the longest and are almost twice as long as carapace length. The fourth pair is the shortest; they are relatively flat and bear hairs (setae). Top: Green crabs are native to the Atlantic coast of Europe and North Related or Similar Species. Africa. (Adapted from map by National Introduced Marine Pest System [NIMPIS], Australia.) Bottom: The green crab is established in bays and On the West Coast, some native estuaries from Monterey Bay, California, northward along the west coast crabs are green and could be and from Maine to the mouth of the Chesapeake Bay along the east mistaken for green crabs. One coast. (Adapted from Perry 2010.)

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such native is the helmet crab (Telmessus cheiragonus), which is distinguished by six spines behind each eye, a pair of long antennae and a body covered in stiff hairs. The green crab is the only shore crab on the Pacific coast with five spines at the edge of the shell behind each eye. Introduction History. Green crabs arrived in the United States in the early 1800s at or near Cape Cod, Massachusetts. The first known report dates to 1817. They began to extend their range northward in the early twentieth century, entering Maine’s waters in the 1950s, and reaching Nova Scotia, Canada, in the 1960s. They were first collected in New Jersey in 1929 and later in Maryland and in Chincoteague Bay, Virginia. East Coast introductions could have come The green crab occupies a wide variety of habitats on sheltered coasts. (P. in ballast water or by crabs Erickson. Reprinted with permission of the MIT Sea Grant College living amongst fouling organ- Program.) isms on the hulls of transoceanic vessels or in the burrows of shipworms living in wooden sailing ships. The green crab was first reported on the Pacific coast in 1989 in Estero Americano, Sonoma and Marin counties, California. About the same time, it appeared in San Francisco Bay. Genetic analyses suggest they came from the east coast of North America and did not represent a direct introduction from Europe or North Africa. It is probable that they arrived in algae used to pack New England baitworms (Nereis virens and Glycera dibranchiata). Green crabs were first collected in Bodega Harbor in 1993 and Humboldt Bay, 1995. They appeared in Oregon, first in Coos Bay (1997), then in Tillamook, Netarts, and Yaquina bays in 1998. Also in 1998, they were first collected in Grays Harbor and Willapa Bay, Washington. It is believed that strong El Nin˜o–derived currents transported green crab larvae northward in 1997–1998. In many of the invaded areas, populations have remained small or have died out. The highest densities occur in Bodega Harbor, but these are slight compared to East Coast infestations. Habitat. Green crabs can be found on protected and semi-protected coasts under both marine and estuarine conditions. They will occupy both rocky and soft sediment shores, seagrass meadows, and tidal marshes. In the United States, they are important members of rocky intertidal communities on the East Coast, but on the West Coast, they do not occupy exposed rocky shores. Juveniles and adults occur in intertidal and subtidal zones to depths of 180 ft. (55 m). Adult green crabs tolerate wide ranges of salinity (4–52 ppt) and

92 n INVERTEBRATES (CRUSTACEANS) temperature (32–86°F or 0–30°C), but larvae require salinities of 26–29 ppt and temperatures of 52–77°F (11–25°C) for successful development. Diet. Green crabs are primarily predators that consume bivalves, including mussels, clams, oysters, and scallops; snails; other crabs; barnacles; and isopods. However, they also eat algae. They may dig nearly 6 in. (15 cm) into sandy or muddy bottoms in search of prey. Life History. Mating occurs after the females molt. The time of the molt varies with geographic location, but most commonly is between June and October. A male carries a smaller female underneath his body until she molts. At that time, she turns over and releases a mass of eggs that she will keep on her abdomen. The male then releases sperm and fertilizes them. The eggs are held by the female through the winter until spring or early summer. When the larvae hatch, they become part of the plankton and drift in the water column for several weeks or months. It appears that tidal currents transport the larvae away from shore and into the open sea. During the planktonic stage, larvae molt and pass through several stages of the life cycle. During the final larval stage, tides bring them back to shore, and they metamorphose and settle to the bottom as juvenile crabs. The juveniles grow to a carapace width of about 0.25 in. (6 mm) before their first winter and 0.5–1.0 in. (13–25 mm) before their second winter. They are sexually mature at 2–3 years of age and may live for 5 years. Impacts. The green crab is believed largely responsible for the decline of New England’s soft shell clam (Mya arenaria) fishery in the 1950s. It is also implicated in declines of the northern quahog (Mercenaria mercenaria) and a scallop (Argopecten irradians). The cultivated Manila clam (Venerupis philippinarum) harvest in Tomales and Humboldt bays, California, declined by 40 percent after the establishment of green crabs. In Bodega Harbor, decreases in the density of small clams (Nutricola spp.) and shore crabs (Menigrapsus oregonensis) are attributed to the introduction of the green crab. It is feared that the commercially important Dungeness crab (Cancer magister) could be similarly affected if the green crab were to expand its range and numbers along the west coasts of the United States and Canada, since it could prey on juveniles. Management. Fencing, trapping, and poisoning were generally ineffective where tried on the East Coast. Washington is attempting to stem the influx of green crabs legislatively by declaring it a deleterious exotic species and prohibiting the possession and transportation of the animal in the state. Aquaculture in Washington is under restrictions that limit the transfer of shells, living animals, and equipment from infested Willaba Bay and Grays Harbor to waters the crab has not yet invaded. Imports of shellfish seed from out-of-state waters where green crabs occur are also restricted.

Selected References “Carcinus maenas (European Green Crab).” Invasive Species Fact Sheet. Washington Department of Fish and Wildlife, 2005. http://wdfw.wa.gov/fish/ans/identify/html/index.php?species=carcinus _maenas. Cohen, Andrew N. “Carcinus maenas (Linnaeus, 1758).” Guide to the Exotic Species of San Francisco Bay. San Francisco Estuary Institute, Oakland, CA, 2005. http://www.exoticsguide.org/species_pages/ c_maenas.html. Perry, Harriet. “Carcinus maenas.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2010. Revised April 25, 2008. http://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=190.

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n Rusty Crayfish Also known as: Crawdad, crawfish Scientific name: Orconectes rusticus Family: Cambaridae Native Range. Rusty crayfish are native to the Ohio, Tennessee, and Cumberland drainage systems in the states of Kentucky, Indiana, Illinois, Ohio, and Tennessee. Distribution in the United States. Outside their native range, rusty crayfish are native transplants in the Great Lakes region, Iowa, Maryland, Missouri, New Jersey, New York, Pennsylvania, and all of the New England states except Rhode Island. Description. The rusty crayfish has relatively large claws that are smooth and have black tips. When closed, the pincers leave an oval gap between them. Color varies from gray-green to reddish brown. The most distinctive feature is a pair of dark-red or rusty spots on either side of the carapace just in front of the abdomen (“tail”); however, these spots are not always present. Maximum length of the body exclusive of the claws is about 4 in. (10 cm). Males are larger than females. Related or Similar Species. Some 65 species of the genus Orconectes are native to the United States. The rusty crayfish has larger, smoother claws than most others. Among those most apt to be found where rusty crayfish have been introduced, the northern clearwater crawfish (O. propinquus) is most similar. However, it lacks the two spots and instead has a dark patch on its tail. Another close relative, the virile crayfish (O. virilis), an invasive in part of its range, can be distinguished by the white bumps on the claws and a very narrow gap when the claws are closed. The calico or papershell crayfish (O. immunis) shows a distinct notch in the closed claws. Neither the virile nor the calico crayfish has black bands at the tips of their claws. Introduction History. The expansion of the rusty crayfish out of its native range is not well documented, but it is assumed that nonresident fishermen, familiar with them in their homes states within the Ohio River basin, brought them to new areas as bait and released them intentionally or accidentally. Rusty crayfish are also popular in school laboratories and sold by biological supply companies. Releases from classrooms are another way rusty crayfish may have entered nonnative waters. Rusty crayfish are commercially harvested for human food, and this provides an economic incentive to introduce them to new locations. Since female crayfish store sperm, a single animal could start a new population. Their introduction to Wisconsin lakes and streams occurred sometime in the 1960s. The first report from southern Minnesota came in 1967. In both of these states, the range has increased dramatically in ensuing years. The most recent introduction was in Maryland, where they were found in the Monocacy River and Susquehanna drainage in 2007. Habitat. These freshwater crustaceans require permanent bodies of water and adequate cover such as rocks, tree limbs, or logs. They inhabit lakes and streams, where they can be found in both still pools and fast-flowing stretches. A variety of bottom types from silts and sands to gravel or rock are used. They do not dig deep burrows as do some of their relatives and so cannot escape when intermittent streams dry up. Diet. Rusty crayfish have unusually high metabolic rates and are therefore voracious and opportunistic feeders. They consume aquatic plants; bottom-dwelling invertebrates such as aquatic worms, snails, bivalves, insect larvae, and crustaceans; detritus; fish eggs; and small fish. Juveniles concentrate on invertebrates such as mayfly, stonefly, and midge larvae, and freshwater shrimp.

94 n INVERTEBRATES (CRUSTACEANS) Life History. Rusty crayfish mate in late summer or early fall, and sometimes in early spring. The male transfers his sperm to the female, which stores them in a seminal receptacle on her belly until the water begins to warm in late April or May. External fertilization takes place when eggs and sperm are simultaneously released by the female. As this happens, she secretes a mucus-like substance called glair that forms white patches on the underside of the tail fan. The fertilized eggs attach to the swimmerets on the underside of the female’s abdomen by means of the glair. Females produce 80–575 eggs. It takes 3–6 weeks for the eggs to hatch. The young continue to hold on to the mother’s swimmerets for several weeks as they go through 3–4 molts. After the young leave the female, they undergo another 8–10 molts before they become adults, usually the year after they hatch. Sexual maturity occurs at a total body length of Top: Rusty crayfish are native to the Ohio, Tennessee, and Cumberland 1.4 in. (3.5 cm). Growth slows river systems. Bottom: Rusty crayfish are invasive native transplants in once the crayfish is mature. many drainages of the Great Lakes region, the central United States, and Females molt only after rethe Northeast. (Both maps adapted from USGS 2008.) leasing their young, usually in June or early July. Males molt twice a year, once in the spring into a sexually inactive form, and again in summer into a reproductive form. The twice-annual molt allows males to become larger than females. Rusty crayfish live 3–4 years. Impacts. Rusty crayfish are aggressive and displace native crayfish, such as the virile crayfish and the northern clearwater crayfish, from shelter and compete with them for food. When the smaller natives are forced from their hiding places, they become vulnerable to increased predation by fish. Declines in these two native crayfish have occurred in lakes in Wisconsin (and parts of Ontario, Canada). Another close relative, Sanborn’s crayfish (Orconectes sanbornii), has been displaced in Ohio in waters where it was not native. Hybridization with the northern clearwater crayfish contributes to the decline of that species. The high metabolic rate of the rusty crayfish means it consumes a lot of food for its size. The destruction of submerged vegetation that provides shelter for invertebrates, young game

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fish and panfish, and forage species for other fish can be particularly damaging to the aquatic ecosystem as it eliminates important and sometimes scarce habitat. They may directly harm native fish by consuming their eggs and reducing the amount of invertebrate prey items upon which juvenile fish depend. Declines have been documented in larval midges, mayflies, and stoneflies and in fish such as bluegill (Lepomis macrochirus), pumpkinseed (Lepomis gibbosus), The rusty crayfish is so named because of the rusty patches of color on smallmouth bass (Lepomis gib- either side of the carapace just in front of the tail. (Jeff Gunderson, bosus), largemouth bass (Micro- Minnesota Sea Grant.) pterus salmoides), lake trout (Salvelinus namaycush), walleye (Sander vitreus), and northern pike (Esox lucius) when rusty crayfish invade. Large numbers of rusty crayfish become a nuisance to swimmers, who are in danger of stepping on them and being pinched by their large claws. Management. Few environmentally sound means of control are available. Commercial harvests may reduce numbers and keep them in check. Some researchers believe that population explosions of rusty crayfish are in part due to the overfishing of predatory fishes, and they recommend restoring healthy populations of sunfish and bass as a way of reducing the impacts of rusty crayfish. The best management practice is to prevent further introductions by educating people about the ways in which this little animal threatens their local waters.

Selected References Gunderson, Jeff. “Rusty Crayfish: A Nasty Invader.” Minnesota Sea Grant, 2008. http:// www.seagrant.umn.edu/ais/rustycrayfish_invader. Pappas, J. “Orconectes rusticus.” Animal Diversity Web, 2002. http://animaldiversity.ummz.umich.edu/ site/accounts/information/Orconectes_rusticus.html. U.S. Geological Survey. “Orconectes rusticus.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2008. http://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=214.

n Spiny Water Flea Scientific name: Bythotrephes longimanus Order: Cladocera Family: Cercopagidae Native Range. Northern Eurasia, from Great Britain and Scandinavia across Russia to the Bering Sea. Since the spiny water flea has been widely dispersed by humans in Europe and Asia to lakes in which it was not native, its true natural range is difficult to reconstruct.

96 n INVERTEBRATES (CRUSTACEANS) Distribution in the United States. This invader is established in all the Great Lakes and has been found in inland lakes in Ohio, Michigan (Long Lake), Minnesota (Greenwood and Flour lakes), New York (Great Sacandaga Lake) and Wisconsin (Stormy Lake and Gile Flowage). Description. The spiny water flea is not an insect, but a crustacean. Many of its features are difficult to discern without magnification. Because they assemble into gelatinous clumps, they often resemble wet cotton batting full of tiny black spots. Each individual in the mass has a well-developed abdomen and a long, thin tail spine. The head is clearly separated from the trunk and bears a single large black compound eye. Two swimming antennae used to propel the animal through water are attached just behind the head. The spine is straight and accounts for more than 70 percent of total body length. The spine bears 1–4 Top: Spiny water fleas occur across northern Eurasia. The exact native pairs of barbs depending upon range is uncertain because people have introduced the species to many the animal’s age. Juveniles have lakes in both Europe and Asia. Bottom: The spiny water flea is invasive a single pair; additional pairs in all of the Great Lakes as well as inland lakes in adjacent states. are added above the spine when (Adapted from Liebig and Benson 2007.) the exoskeleton covering the trunk of the body is shed to allow for growth. Two morphs representing different reproductive modes (see under Life History) are present. Parthenogenically reproduced individuals, all females, have longer tail spines with an obvious “kink” in the middle of the spine and, when fully developed, have three pairs of barbs resulting from two molts. Sexually reproducing females will acquire four pairs of barbs during three molts. (The parthenogenically reproduced females were once believed to be a separate species and identified as B. cederstroemi.) Females are also identifiable because they carry their eggs in a brood pouch that balloons from the back of the body. Males will not gain a new pair of barbs during their final molt and end up with only two pairs.

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Spiny water fleas have four pairs of legs. The first pair is longer than the others and used for snaring prey. The others are used to grasp the prey while it is being eaten. Average adult size is 0.4 in. (1 cm). The spiny water flea is a crustacean barely visible with the naked eye. Related or Similar Species. (Microscopy by Howard Webb.) This tiny crustacean has a unique body shape with a long tail spine that clearly distinguishes it from freshwater zooplankters native to the Great Lakes. Another exotic cladoceran, the fishhook water flea (Cercopagis pengoi), also collects into masses, but individuals can be separated from spiny water fleas by virtue of their angled tails that end in a distinct loop or “fishhook” and their tiny eyes. Introduction History. The first live specimens of spiny water flea were retrieved from Lake Huron in 1984. The next year, they were found in Lakes Erie and Ontario. By 1986, they had made their way to Lake Michigan, and by 1987, they had invaded Lake Superior. By early 2002, they had been reported from 66 lakes in the northern United States and southern Canada. In 2007, spiny water fleas were discovered in Stormy Lake, Wisconsin, and in 2008, they were found in Great Sacandaga Lake, in New York’s Adirondack Mountains. Genetic analysis has traced the source of the invasion to the port of St. Petersburg, Russia. Spiny water fleas are native to nearby Lake Lagoda. During spring snowmelt, they are carried down the Neva River to the harbor, where the water becomes fresh or only slightly brackish. Freighters, which had brought wheat from the United States, return empty and therefore take up ballast water and any zooplankton contained in it at St. Petersburg. They then discharge that water when they next take on grain in American ports in the Great Lakes. Local dispersal from the Great Lakes to inland lakes probably occurs by means of contaminated fishing gear and boats. Habitat. Spiny water fleas do best in deep lakes in temperate climates. They will inhabit both large and small lakes, and may live in shallow lakes and rivers as well as in brackish waters. They are limited to water temperatures of 39–86°F (4–30°C) and salinities of 0.04–8.0 percent. Optimal conditions are temperatures of 50–75°F (10–24°C) and salinities of 0.04–0.4 percent. Females are conspicuous to predatory fish during daylight hours because of their large eyes and brood pouches, and thus undergo daily vertical migrations. During daylight hours, they move lower into the water column and are usually at depths of 30–65 ft. (10–20 m). They swim up closer to the surface where food is more abundant and at night, when most will be found within the top 30 ft. (10 m) of the water column. Diet. Spiny water fleas are tiny predators that feed on smaller, herbivorous zooplankters. Daphnia spp. and other water fleas are preferred prey, but they also eat copepods and rotifers. Studies show that a single spiny water flea can consume 20 prey items a day. Life History. Spiny water fleas have a complex life cycle involving both sexual and asexual reproduction. Most of the time, females reproduce by cloning (parthenogenesis) and produce 1–10 eggs that develop into new females without fertilization by males. A new generation may be produced every two weeks in the summer, when temperatures are warm and food abundant. Under these conditions, males are rare in the population. However, sex of the young is determined not by genetics, but by the environment. When

98 n INVERTEBRATES (CRUSTACEANS) conditions deteriorate in the fall, males begin to be produced. They mate with females that then produce “resting eggs.” At first, the resting eggs are carried in the brood pouch, but eventually they are released into the water and settle to the bottom of the lake, where they go into a near-dormant phase (diapause) in order to survive the cold of winter. As water temperature rises to 39°F (4°C) and above in the spring, the eggs hatch into females that will reproduce parthogenetically and make possible rapid population growth during favorable conditions. The brief sexually reproducing part of the life cycle promotes both genetic diversity and dispersal capability. Impacts. The initial impact of the introduction of spiny water fleas was as a nuisance to fishermen. Hundreds of these cladocerans can clump onto fishing lines and downrigger cables, especially at connections and swivels, and clog the first guide of an angler’s rod. Sometimes it becomes impossible to reel in the catch, and the line must be cut. With time, ecological impacts became evident. The community structure of the zooplankton community can be altered by heavy predation on small herbivorous crustaceans such as Daphnia, copepods, and rotifers. In Lake Michigan, both D. retrocurva and D. pulicaria populations collapsed after the introduction of water fleas, and populations of another tiny cladoceran, Holopedium gibberum, declined dramatically. In consuming these animals, spiny water fleas also compete for food with the plankton-feeding larvae of several fish species as well as with other cladocerans, such as the giant water flea (Leptodora kindtii), which declined in some lakes when spiny water fleas were introduced. Such results are not always duplicated in smaller lakes. Impacts on fish populations are not clear. Juvenile fish of species that feed heavily on Daphnia may suffer, affecting annual recruitment rates of species such as yellow perch (Perca flavescens). The barbed tail of the spiny water flea cannot be accommodated in the small mouth gape and throats of young fish, so they cannot shift their diets to include the invader species. On the other hand, adult yellow perch, as well as white perch (Morone americana), bass (Micropterus spp.), and alewife (Alosa pseudoharengus) selectively prey on spiny water fleas and could be helped by a new, seasonally abundant forage species. These fish in turn are eaten by larger game fish such as Chinook salmon (Oncorhynchus tshawytscha) and lake whitefish (Coregonus clupeaformis), so economically important fisheries could be affected in a positive manner. Management. Control measures are aimed at preventing the spread of the spiny water flea to other inland lakes. Educational campaigns encourage fishermen to clean gear properly and empty bilges, livewells, and bait buckets responsibly before moving from one lake to another.

Selected References Caceres, Carla E., and John T. Lehman. “Spiny Tailed Bythotrephes: Its Life History and Effects on the Great Lakes.” Minnesota Sea Grant College Program. University of Minnesota, 2004; last modified January 26, 2010. http://www.seagrant.umn.edu/exotics/spiny.html. Liebig, Jim, and Amy Benson. “Bythotrephes longimanus.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2010. Revised January 25, 2007. http://nas.er.usgs.gov/queries/ FactSheet.aspx?SpeciesID=162. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Bythotrephes longimanus (Crustacean).” ISSG Global Invasive Species Database, 2005. http://www.issg.org/database/species/ecology.asp?si=151&fr=1&sts=sss.

HONEYBEE TRACHEAL MITE n 99 Sikes, Benjamin. “Spiny Water Flea.” Invader of the Month. Institute for Biological Invasions, University of Tennessee, Knoxville, 2002. http://invasions.bio.utk.edu/invaders/fleas.html.

n Arachnids n Honeybee Tracheal Mite Scientific name: Acarapis woodi Order: Trombidiformes Family: Tarsonemidae Native Range. Uncertain. Honeybee tracheal mites were first described from collections made in dying bee colonies on the Isle of Wight in the English Channel in 1921. They were responsible for wide-ranging honey bee mortality in Europe in the early part of the twentieth century. Distribution in the United States. Throughout the continental United States, except Alaska, in both managed and feral honey bee colonies. Description. Invisible to the naked eye, tracheal mites have white oval bodies with a shiny, smooth cuticle. The body and legs have several long fine hairs. The mouth parts are beak-like and elongated. Females are 143–147 microns long and 77–81 microns wide; males are 125–136 microns long and 60–70 microns wide. Few outward symptoms are evident in infected bees until the infestation is severe. Then bees may develop disjointed, “K” wings and become unable to fly. Honey production may decline. Sudden death of the hive during winter is a sign that the honeybee tracheal mite may be present. Verification requires dissection of the dead bees and examination of the tracheae, which will be brown instead of clear or white as in healthy bees. Introduction History. Honeybee tracheal mites were unknown in North America prior to 1980, when they were detected in Mexico, some 200 miles (320 km) south of the U.S. border. They were first discovered in the United States at a commercial beekeeping enterprise in Weslaco, Hidalgo County, Texas, in early July 1984. The following month, they were found in New Iberia, Louisiana, and by October 1984, they were being reported in Florida, Nebraska, New York, North Dakota, and South Dakota. By August 1985 they infested bee colonies in 17 states. The rapid spread of the mite was facilitated by migratory beekeepers, who truck bee colonies from southern states northward to pollinate various crops. The commercial bee business also contributed to the spread by selling queens and package bees. Mites move quickly through a colony via bee-to-bee contact in the hive. Workers and drones drifting from hive to hive disperse the mite through entire apiaries or from one apiary to another. Bees also encounter mites when they rob honey from other hives; and colonies weakened by heavy mite infestations are particularly vulnerable to robbing. Since mites cannot live more than a day outside the bee host, they readily leave dead bees and hitchhike to new colonies inside robber bees. Normal swarming of bees can also spread the tracheal mite to new areas. Habitat. Honeybee tracheal mites are internal parasites that live within the breathing tubes (trachea) of adult bees. They prefer the larger tubes at the base of the bees’ wings that provide oxygen to the flight muscles. Occasionally, they occur in the air sacs. They infest only European honey bees (Apis mellifera), Africanized honey bees (Apis mellifera scutellata; see Insects, Africanized Honey Bee) and Asian honey bees (Apis cerana).

100 n INVERTEBRATES (ARACHNIDS) Diet. Tracheal mites puncture the walls of the breathing tubes and feed on the blood (hemolymph) of workers, drones, and queen bees. Life History. The life cycle consists of four stages: egg, larva, a resting stage nymph, and adult. The female mite enters a bee shortly after it emerges from its cell by moving through the first thoracic spiracle into the breathing tubes. She remains in the host for the rest of her life or until the bee dies. Three or four days after arrival, she lays 5–7 eggs, which hatch in another three or four days. Adult male mites are mature 11–12 days after the eggs are laid; females are mature in 14–15 days. Gravid females crawl to the tip of a bee hair and “jump” to a new host, entering through the breathing pores (spiracles) to lay their eggs. They tend to attack young bees less than 24 hours old. Mite populations tend to be cyclical; heaviest infestations occur in winter, when the bees Top: The origins of the honeybee tracheal mite are unknown. It was first are confined and crowded in reported affecting domestic honey bees in England. Bottom: The the hive, and then decline in honeybee tracheal mite is found throughout the lower 48 states and on summer. O’ahu, Hawai’i. Impacts. Initially, the introduction of the tracheal mite caused widespread losses of bee colonies and even entire apiaries throughout the United States. Problems were especially severe in the more temperate parts of the country, where bees cluster in confinement within the hive during the winter months. Highest bee mortality usually occurs in late winter. Infected bees often show no signs of a problem, though pollen collection and honey production may decline as a bee weakens. The mites kill by clogging the breathing tubes with their bodies and waste products. Normally elastic tracheae become stiff and brittle, and flight muscles atrophy. Furthermore, hemolymph contains agents that act as antifreeze, so as the mites consume the bee’s body fluid, it reduces its ability to withstand low temperatures. The effects of mite infestation, known as acarine disease, may remain in a colony for years with little damage. Worker bees and queens become less susceptible to infestation as they age. It appears that most honey bees in the United States have developed some resistance

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A. View of honeybee tracheal mite from above. B. Lateral view of honeybee tracheal mite. C. Mites clogging a bee’s trachea. (Pest and Diseases Image Library, Bugwood.org.)

to or tolerance of mite infestations and that the problem of acarine disease is not as severe as it was in the 1980s and 1990s. Its impacts may have been overshadowed by the introduction of the varroa mite (Varroa destructor) in 1987 (see Arachnids, Varroa Mite). Management. After the initial discovery of mites in Texas in 1921, the federal Honey Bee of Act of 1922 was passed. It prohibited the importation of any honey bee into the United States. The law has been relaxed somewhat since then to allow the import of bees from Canada, where mite infestations are unknown, and a few other mite-free countries. Chemical control may involve fumigation with menthol crystals. Grease patties, made of vegetable shortening and sugar and available commercially, keep mites from infesting young bees because the oily bees apparently do not “smell” right to mites. Evaporating formic acid is also very effective in controlling tracheal mites and has the added bonus of reducing infestations of the varroa mite.

102 n INVERTEBRATES (ARACHNIDS) Several stocks of honey bees, including the Buckfast bee, have been bred to resist tracheal mites. The bees still become infested, but only at levels too low to cause significant damage. Use of these bees eliminates the need to treat the colony with chemicals.

Selected References Ambrose, John T., and Michael Stanghellini. “Tracheal Mites.” Note 2.02. Beekeeping. Insect Pest Management, Department of Entomology, North Carolina State University, 2001. http:// www.cals.ncsu.edu/entomology/apiculture/PDF%20files/2.02.pdf. Collison, Clarence H. “Honey Bee Tracheal Mite.” Publication 1753, Extension Service of Mississippi State University, 2009. http://msucares.com/pubs/publications/p1753.htm. Hunt, Greg. “Parasitic Mites of Honey Bees.” Beekeeping. E-201-W. Department of Entomology, Purdue University Cooperative Extension Service, 2006. http://extension.entm.purdue.edu/publications/ E-201.pdf. Sammataro, Diana. “An Easy Dissection Technique for Finding the Tracheal Mite Acarapis woodi (Rennie) (Acari: Tarsonemidae), in Honey Bees, with Video Link.” International Journal of Acarology, 32(4), 2006. Available online at http://entnemdept.ufl.edu/HoneyBee/files/speaker _notes/exp_wksp_Tracheal_Mite_Dissection_Notes.pdf.

n Varroa Mite Scientific name: Varroa destructor Order: Parasitiformes Family: Varroidae Native Range. Mainland Asia. It is known to be endemic to Japan, Korea, and Thailand, where its host is the Asian honey bee Apis cerana. At some point it shifted hosts to the European honey bee; and, in 1963 in Singapore, it was first identified on European honey bees as a new species. Previously it had been classified as Varroa jacobsoni, a parasitic mite of the Asian honey bee known from much of mainland and insular Asia. Distribution in the United States. In all 50 states, in both wild and managed honey bee colonies. Description. This small arachnid is an external parasite of honey bees. Tick-like, it has a flattened oval body and eight legs. Adult females are reddish brown and measure about 0.06 in. (1.5 to 1.99 mm) in width, approximately the size of the head of a pin. Their bodies are curved to allow them to squeeze into the abdominal folds of a bee and thereby be protected from the bee’s normal cleaning habits. Males are smaller and spherical in shape; they are yellowish and have tan legs. Both sexes are visible to the unaided eye. Symptoms of severe varroa infestations include an accumulation of dead bees at the entrance to a hive, the uncapping and destruction of brood cells by worker bees, and deformed legs and wings on adult bees. Related or Similar Species. The bee louse (Braula coeca), a tiny wingless fly, is similar in size and color, but has six legs instead of eight. It is rare in most hives today since it succumbs to treatments used to control the varroa mite. Introduction History. A single varroa mite was discovered in Maryland in 1979, its source unknown. It showed up again in 1987, this time in Florida and Wisconsin. It has since spread rapidly throughout the United States. The last state invaded was Hawai’i, where the first infestation occurred in O’ahu in 2007; the following year, the varroa mite was found in honey bee colonies on the Big Island.

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Mites are transported from hive to hive by drifting workers and drones. Worker bees also pick up mites when they rob honey from smaller colonies. People can move mites from place to place when they transport infested colonies of bees to fields and orchards for pollination and through the importation of infested package bees. Swarming bees may carry mites to other apiaries or to feral populations. It is also possible that mites are spread short distances on bumblebees and other nectar-feeding insect hosts. Habitat. Varroa mites are usually found on the thoraxes and abdomens of larvae, pupae, and adults of all races of the European honey bee (Apis mellifera) and the Africanized honey bee (A. mellifera scutellata; see Insects, Africanized honey bee). All life stages inhabit the brood cells of honey bees; adult females will emerge with the young bee and live on drone and worker bees. The varroa mite also occurs on the American bumblebee (Bombus penn- Top: The varroa mite is known to be native to Japan, Korea, and Thailand sylvanicus), flower fly (Palpada and perhaps other parts of Asia. It originally infested the Asian honey bee vinetorum), and rainbow scarab but later adopted the European honey bee as its host. Bottom: Varroa mites beetle (Panaeus vindex), but are found in all 50 states, where they infest feral and managed bee colonies. cannot reproduce on them. It is also a parasite of Asian honey bees (A. cerana and A. koschevnilovi). Diet. Varroa mites suck the hemolymph (“bee blood”) of developing honey bee larvae and mature adults. They pierce the soft skin of larvae and the tougher integument of adults to obtain this fluid. Like other arachnids, they inject enzymes that predigest a bee’s tissues so they can consume them also. Life History. The life cycle of varroa mites is synchronized with that of its host, the honey bee. Females enter the brood cells of honey bees just before worker bees cap the cell, when the bee larva is five days old and about to pupate. About three days later, she lays her first egg, which usually is unfertilized and becomes a male. Later, she will lay a fertilized egg every 30 hours; these become females. All immature mites feed on the bee larva and must mature and mate before the bee emerges from its cell. It usually takes five to eight days for the females to mature and a few days less for the male. The male mite dies in the cell, but

104 n INVERTEBRATES (ARACHNIDS)

A. Varroa destructor. B. Varroa mites at base of honey bee brood cell. C. Mite on honey bee pupa. (Scott Bauer, USDA Agricultural Research Service, Bugwood.org.)

mated females will leave the cell on the host bee to seek new brood cells, preferably those of drone larvae, where the process begins again. The average lifespan is about 50 days during the breeding season. In winter, when brood-rearing by bees declines, mites live solely on adult bees in the hive. Adult mites can survive only a few days without bees. Impacts. Heavy infestations of varroa mites cause young bees just emerging from their brood cells to have malformed wings, legs, and bodies. On adult worker bees, they may affect the flight behavior, orientation, and success in returning to the hive laden with pollen and nectar. As worker bees die off, fewer bees are available to tend to the brood and collect nectar, and the colony weakens. Weak colonies are susceptible to having their honey stores robbed by stronger hives. Eventually, the colony dies. In temperate climates, the death of a colony may take 3–5 years; but in the milder climate of Florida, infested bee colonies have died within seven months. Mites transmit several RNA viruses that kill bees by compromising their immune systems. These include deformed wing virus (DWV), acute bee paralysis virus (APV), and slow

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paralysis virus (SPV). They result in a condition known as parasitic mite syndrome, which can destroy a colony in a few months. Without treatment, colonies—indeed, entire apiaries—can be wiped out by varroa mites. In the United States, most wild (feral) bee populations, where treatment is not an option, have been decimated by this invasive arachnid. Pollination of numerous field and orchard crops depend upon honey bees. Their loss would have devastating economic impacts. Management. Chemical means are available to detect varroa mites and control them in a bee colony. A common treatment involves hanging strips impregnated with fluvalinate (Apistan) in the brood nest area for about a month. As dead mites fall off bees, they can be collected on sticky paper or a fine mesh placed screen on the bottom of a hive. This product allows detection of low-level infestations. Such strips can also be used as a control measure. A problem with this method is the development of fluvalinate-resistant mites. Another chemical treatment using coumaphos (CheckMite+) is also very effective, but has the disadvantage of employing a dangerous organophosphate. Two formulations of thymol (oil of thyme—Api-Life VAR and Api-Guard) and one using fenpyroximate (Hivastan) are also available to beekeepers. All should be applied with careful adherence to instructions. Research suggests biological controls may be implemented in the future. One candidate is a strain of the fungus Metarhizium anisopliae that is lethal to varroa mites. Another possibility is genetic engineering to develop a bee resistant to mite infestation. Asian bees (Apis cerana), the original host for varroa mites, are aggressive groomers and cleaners and remove mites from other bees by grooming and chewing the mite. They decap infested brood cells and clean them out, discarding dead and dying larvae at the entrance to the colony. Bees that develop faster in the brood cell can outpace the developing mites and emerge with fewer of them. Bee breeders can select for queens that produce workers that are good at grooming, that clean out brood cells, and that have quicker development times than average European honey bees. It is essential to stem the spread of infested colonies through constantly surveying bees for the presence of the mite. Captured swarms, package bees, and other new colonies should be quarantined away from the rest of the apiary and examined for mites before being allowed contact with existing colonies.

Selected References Bessin, Ric. “Varroa Mites Infesting Honey Bee Colonies.” ENTFACT-608. College of Agriculture, University of Kentucky, 2001. http://www.ca.uky.edu/entomology/entfacts/ef608.asp. Hunt, Greg. “Parasitic Mites of Honey Bees.” Beekeeping. E-201-W. Department of Entomology, Purdue University Cooperative Extension Service, 2006. http://extension.entm.purdue.edu/publications/ E-201.pdf. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Varroa destructor (Arachnid).” ISSG Global Invasive Species Database, 2006. http:// www.issg.org/database/species/ecology.asp?si=478&fr=1&sts=sss. Reid, Brendan. “Varroa Mite (Varroa destructor).” Introduced Species Summary Project, Columbia University, 2004. http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/inv_spp_summ/ varroa_destructor.html. Sanford, M. T., H. A. Denmark, H. L. Comroy, and L. Cutts. “Featured Creatures: Varroa mite (Varroa destructor).” University of Florida Institute of Food and Agriculture, 2007. http://www.entnemdept .ufl.edu/creatures/misc/bees/varroa_mite.htm.

106 n INVERTEBRATES (INSECTS)

n Insects n Africanized Honey Bee Also known as: AHB, Killer bee Scientific name: Apis mellifera scutellata Order: Hymenoptera Family: Apidae Native Range. The African parent of the hybrid Africanized honey bee derives from eastern and southern Africa, where Apis mellifera scutellata occurs from Kenya south to the Indian and Atlantic coasts of South Africa. Bees from Tanzania were taken to Brazil, where hybrids or Africanized honey bees were developed in Rio Claro in the state of Sao Paulo. From there, they spread throughout tropical South America and Central America and into the United States (see under Introduction History). Distribution in the United States. As of July 2009, Africanized honey bees were established from Texas and Oklahoma west through New Mexico and Arizona to southern Nevada and southern California. Isolated swarms have been reported in southern Utah, Arkansas, Louisiana, and Florida. Description. The Africanized honey bee is a hybrid species and nearly indistinguishable from the common domesticated European honey bee, one of its parents. The hybrid form requires inspection and analysis in a laboratory to positively identify it. Behavioral traits do set it apart, however. It is usually recognized by its extremely aggressive nature, the guarding of a large area around its nest, frequent swarming, and nest location. Worker bees, all sterile females, are about 0.75 in. (19 mm) long, imperceptibly smaller than European honey bees. Drones, all males, have narrower bodies and are somewhat longer. Queens are larger still and more robust, with enlarged abdomens. The bees’ bodies are covered with a yellow-brown fuzz and marked with black stripes. They have four clear wings and six legs, all attached to the middle body segment (thorax). The abdomen is larger than the thorax and ends in a stinger. The venom is not as toxic as that of European bees, but since large numbers of bees mass to defend their nest, the multiple stings that result can be dangerous, indeed lethal, especially to sensitive persons. Related or Similar Species. The European honey bee (Apis mellifera) is more a docile domesticated animal selected for characteristics that suit it for easy handling by humans. It produces and hoards more honey than Africanized honey bees and swarms less often. European honey bees nest in large cavities in trees, in hollow walls, and in beehives, where they develop from egg to adult a bit more slowly than their hybrid descendents. European honey bees have adapted to the cold winters of the mid-latitudes, in part by storing large amounts of honey in their hives. Introduction History. African honey bees were brought to test sites in Rio Claro, Brazil, in 1956 by a Brazilian geneticist, Dr. Warwick Kerr. European honey bees had not fared well in subtropical and tropical parts of South America. The hope was that crossing them with bees from tropical Africa would improve both their honey production and survival rates by selecting for the climatic adaptations of the African parents and the docility and honeyproducing attributes of the European ones. In 1957, 26 African queens swarmed with European worker bees and escaped the experimental apiary. These bees hybridized with commercial and feral populations of European honey bees, but in the wild retained most of the traits of the African line, particularly the aggressive defense of their nests. They rapidly

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spread through all of subtropical and tropical South America except Chile, and north through Central America. They were first identified in Mexico in 1985. The rate of spread averaged 125–180 mi. (200–300 km) a year. This dispersal was largely unaided by humans. In 1990, Africanized honey bees reached Hidalgo, Texas, on the Mexican border. By 1993, they were in Arizona, and by 1994, they were discovered near Blythe in southern California. In 1996 they were found to the north in Lawndale, California. Since that time, the dispersal rate has, for unknown reasons, slowed. Africanized honey bees dispersed across South and Central America by swarming and by hybridizing with existing feral and domestic colonies of European honey bees. Anecdotal evidence suggests European queens breed preferentially with Africanized drones and that Africanized queens will enter the hives of European honey bees and kill and replace the European queen. Top: The African parent of the Africanized honey bee has its origins in It is believed that cold winter southern and eastern Africa. The hybrids between African bees and the temperatures will prevent their European honey bee were developed in Rio Claro, Brazil. Bottom: establishment very far north of Africanized honey bees are established in southern states from the present U.S. distribution California to Florida. Short-lived colonies may appear as far north as Virginia. (Adapted from “Spread of Africanized Honey Bees by Year, by limits, and that high rainfall will County.” USDA Agricultural Research Station, 2009. http://www.ars restrict their spread east of .usda.gov/Research/docs.htm?docid=11059&page=6.) Texas. Traits adaptive to tropical environments will be selected against in colonies living in temperate climates. Disjunct populations in Florida may have resulted from swarms arriving on ships; Africanized honey bees have been trapped regularly at Florida’s deep-sea ports. Occasionally, temporary infestations occur as far north as Virginia, perhaps the result of bees being transported accidentally on trains. Habitat. The hybrid Africanized bees are less selective in habitat than the European honey bee and nest in smaller numbers. Their nests may hang from exposed tree limbs or under the eaves of buildings, or may be constructed in old tires and empty containers, cement blocks, rotted logs, animal burrows, rock piles, and so forth—all places avoided

108 n INVERTEBRATES (INSECTS) by European honey bees. They are apparently restricted to tropical and subtropical climates, particularly those with distinct wet and dry seasons, and are seldom found poleward of 34° latitude. Along the Gulf coast, their failure to become well established east of Texas has been attributed to the higher annual precipitation in the Gulf coast states (greater than 50 in. or 1,270 mm a year) and possibly to greater rates of parasitism by varroa mites (Varroa destructor; see Arachnids, Varroa Mite) in those more humid areas. Diet. Africanized honey bees consume nectar and pollen. Nectar is converted to honey and becomes the bees’ main source of carbohydrates. Pollen constitutes the main source of protein. Most flowering plants serve as food sources. Life History. A queen mates with a drone to produce a fertilized egg, which develops into a female worker bee. Unfertilized eggs become male drones. If larvae are fed royal jelly—a mixture of glandular secretions—they develop into queens. The life cycle involves egg, larva, pupa, and adult. Eggs are attached to the bottom of cells in the comb and hatch in approximately 60 hours. The larvae are then fed secretions from the heads of young nurse bees. If the egg is to become a worker, it is sealed into the cell eight days after hatching. Within 24 hours, the larva spins a cocoon, and the next day enters the prepupal stage. A day later, the white, immobile pupa has formed. Adult worker bees emerge 18.5 days after the egg was laid; queens about 16 days after laying. Worker bees live about 30 days, drones 5–10 weeks, and queens 1–3 years. As a colony grows, it will split into two or more colonies. A queen and a group of workers leave the nest together in a “swarm.” A new queen hatches in the original nest, mates, and begins egg-laying. Africanized bees swarm frequently (as often as every six weeks) and at any time of year. Their survival strategy, evolved in an African cultural environment in which people were and still are bee hunters and honey thieves rather than beekeepers, is to invest energy into large numbers of offspring and produce many reproductive swarms. They fiercely defend their nests, but they also abandon them readily and start new colonies elsewhere. Impacts. The most direct impacts of Africanized honey bees are on the beekeeping industry and agriculture. These hybrid bees compete with domestic European honey bees and, by mating with European queens, take over hives. The Africanized bees not only are more

A. The Africanized honey bee is a hybrid species and can only be distinguished from the European honey bee by laboratory analysis. (Jeffrey W. Lotz, Florida Department of Agriculture and Consumer Services, Bugwood.org.) B. Africanized honey bee (left) and European honey bee (right). Normally color differences do not allow distinction between the two. (Scott Bauer, USDA Agricultural Research Service, Bugwood.org.)

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difficult to handle and much more apt to abandon their hives, but they also produce less honey than European honey bees. Honey bees are extremely important pollinators of many orchard and field crops, and beekeeping is a commercial enterprise of its own. One estimate has honey bees adding $10 billion or more each year to the value of some 90 crops in the United States. The problem in handling the aggressive hybrid bees has led some to give up beekeeping altogether and others to adopt more labor-intensive and therefore costly management practices (see under Management). Africanized honey bees are best suited to subtropical areas of the United States, the very states where the packaged bee and queen industry is located. Africanized honey bees are dangerous to people who venture too close to their nests or otherwise disturb them because of the multiple stings victims receive from the hundreds of bees that attack en masse at the slightest provocation. Their preferred nesting locations bring them into close proximity to humans, increasing the likelihood of bee-human interaction. The bees can sense intruders more than 50 ft. (15 m) away and be irritated by the vibrations of power equipment more than 100 ft. (30 m) distant. They may chase people whom they feel are threats for 0.25 mi. (0.4 km). Some people have died from as few as 100–300 stings, but usually it takes 500–1,000 stings for the attack to be fatal. Livestock and pets are at risk as well as humans. Effects on natural ecosystems and native pollinators are unknown. Competition from Africanized honey bees could displace other nectar- and pollen-feeding invertebrates from their more important food resources. Management. As the invasion spread through South and Central America, beekeeping and honey production suffered significant declines at first. Then beekeepers learned new skills to better manage their Africanized hives and reduce the frequency of bee attacks. Among the benefits to agriculture of these new practices was the production of pollinators many farmers feel are superior to the European honey bee. A simple change was to keep each bee colony on its own, separate hive stand so that one hive could be worked without disturbing neighboring colonies. More smoke is used well ahead of working with the bees to calm them and possibly mask alarm pheromones. In addition, a change from traditional black bee veils to white ones as part of the beekeeper’s protective gear minimizes attacks. In the United States, the strategy has been to try to diminish the infusion of African genes into bee populations by either “drone-flooding” or frequent requeening with known European queens. Drone-flooding involves adding European drones to a colony to lessen the chances of the queen mating with an Africanized one. To avoid painful or even deadly encounters with Africanized bees, people in areas where these bees now occur should remain alert to their potential presence when outdoors and stay away from known nests or swarms. Anyone knowing the location of hives or swarms should obtain professional help to remove them. If an attack occurs, immediately run away in a straight line, covering your face if possible, and seek shelter in a car or building. Do not swat at them or try to hide in a pool of water. Scrape stingers off the skin; do not squeeze them, as that will cause them to release more venom. Wash and apply ice to stings and see a doctor if breathing becomes labored. People can bee-proof their homes and yards by sealing openings, regularly inspecting eaves, and removing other potential nest sites.

Selected References “Africanized Honey Bee.” Oklahoma Invasive Species Site. Oklahoma State University, 2007. http:// oklahomainvasivespecies.okstate.edu/africanized_honey_bee.html. “Africanized Honeybee Pest Profile.” California Department of Food and Agriculture, 2010. http:// www.cdfa.ca.gov/phpps/pdep/target_pest_disease_profiles/ahb_profile.html.

110 n INVERTEBRATES (INSECTS) Ellis, Jamie, and Amanda Ellis. “African Honey Bee.” Featured Creatures, Publication Number EENY429, University of Florida Institute of Food and Agricultural Sciences, 2008 http:// entomology.ifas.ufl.edu/creatures/misc/bees/ahb.htm. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialty Group (ISSG). “Apis mellifera scutellata (Insect).” ISSG Global Invasive Species Database, 2005. http:// www.issg.org/database/species/ecology.asp?si=325&fr=1&sts. Sanford, Malcolm T., and H. Glenn Hall. “African Honey Bee: What You Need to Know.” Fact Sheet ENY114, Entomology and Nemotology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, 2005. http://edis.ifas.ufl.edu/mg113. Villa, J. D., T. E. Rinderer, and J. A. Stelzer. “Answers to the Puzzling Distribution of Africanized Bees in the United States or ‘Why Are Those Bees Not Moving East to Texas?’ ” American Bee Journal 142(7): 480–83, 2002. http://www.ars.usda.gov/research/publications/Publications.htm ?seq_no_115=133427.

n Argentine Ant Scientific name: Linepithema humile Synonym: Iridomyrmex humilus Family: Formicidae Native Range. South America: The Argentine ant is native to northern Argentina, southern Brazil, Uruguay, and Paraguay. Genetic studies reveal that those ants in the continental United States derive from the southern Parana´ River region of Argentina. Distribution in the United States. Argentine ants are widely established in California. They are also found in southern Arizona. In the Gulf coast states, they are common from east Texas to Florida. They have also been reported in Georgia, South Carolina, and North Carolina. In Hawai’i, they are spreading through Haleakala National Park on Maui. Populations also exist on the Big Island. Description. The Argentine ant is medium to dark brown and about 0.1 in. (2–3 mm) long. The workers all have the same morphology. Their bodies are smooth and shiny without hairs on the back of the head or thorax. The petiole or waist segment consists of a single upright scale. When viewed head-on, the eyes do not protrude beyond the outline of the face. These ants lack stingers or acidopores. They move quickly along strong foraging trails, often in large numbers. When crushed, they give off a musty odor. Related or Similar Species. Most other ants give off an acidic odor when crushed. Introduction History. The Argentine ant entered the United States at New Orleans in the early 1890s. The first record dates to 1891. It probably arrived in shipments of coffee or sugar from Argentina and may have spread across the southern United States on trains. It was first documented in California in 1907. Reintroductions to the Southeast may have occurred in the early 1900s in cargo arriving at Gulf ports from California. Argentine ants came to Hawai’i during World War II, presumably with shipments of goods on troop ships from California. Local dispersal may be facilitated by the ants’ predilection to move their nests frequently. Therefore, they can rapidly take advantage of new opportunities for new nest sites in potted plants or in refuse, items that humans will further disperse. They also “raft” when their habitat is flooded and thereby move to new areas. New colonies can be established with as few as 10 workers and a queen. The invasive success of Argentine ants has been attributed to the genetic similarity of all individuals, a consequence of either just one or very few colonizing events. The argument has been that the ants fail to recognize individuals born of different queens as “others,” so all can live together in massive supercolonies formed by budding. In other words, they lack

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population-control measures that would have resulted from competition among colonies. Others maintain that the reason supercolonies in areas to which the Argentine ant has been introduced are so much larger than in their native range is due to a reduced parasite load and reduced competition from other ant species in the introduced range. Those two factors allow supercolonies to survive longer and attain great sizes, an aid when invading new territory. Habitat. Argentine ants prefer moist environments with moderate temperatures. They can be found in a variety of natural, disturbed, and manmade habitats, from agricultural areas (especially citrus orchards) to natural forests and grasslands, and in urban areas both indoors and outdoors. In drier regions, such as southern California, they prefer to be near perennial streams or irrigated fields and human dwellings. They are the most common “house ant” in California, particularly in urban San Diego Top: Argentine ants are native to the Paraguay-Parana´ River basin of and Los Angeles. Usually re- northern Argentina, southern Brazil, Paraguay, and Uruguay. Bottom: stricted to lower elevations, they Argentine ants are established in California and the Gulf coast states; disare invading alpine areas in junct populations occur north of these areas. In Hawai’i, they occur on Hawai’i. Argentine ants nest in Mau’i and the island of Hawai’i. (Adapted from “Sources of Introduced Argentine Ants Tied to Reduced Genetic Variation.” University of mulch or soil, in rotting wood, California, San Diego, news release, n.d. http://ucsdnews.ucsd.edu and in garbage. Nests are often ?rewsrel/science/mcants.htm.) found in soil under objects or near tree roots and in potted plants or under walkways. Diet. This ant prefers sweet substances. It tends aphids and consumes the honeydew that these and other insects such as mealybugs and scales secrete. It also feeds on nectar and the body fluids of dead animals. Occasionally, it will capture small, slow-moving insects or take their eggs. In homes it seeks sugar, proteins, and water. Life History. Queens and drones mate in the nest, unlike many ants that perform nuptial flights. All worker ants are sterile. Nonetheless, worker ants can rear eggs and direct the development of early instar larvae into reproductive females without queens being present.

112 n INVERTEBRATES (INSECTS) A colony expands and disperses by budding new subcolonies. The result can be a huge supercolony with many queens. The production of males apparently is determined by the quantity of food available to larvae. Workers may kill the queen after a year and accept a newly mated queen in her place. Impacts. Argentine ants are aggressive and have displaced native ant species in various parts of the world. In California, local extinctions of natives such as army ants (Neivamyrmex spp.) and harvester ants (Messor The petiole or waist of the Argentine ant has a single upright scale, clearly spp. and Pogonomyrmex spp.) visible in this photograph. (Eli Sarnat.) have occurred. Ants and other native insects are often important seed dispersers and plant pollinators. If the natives are severely reduced by invading Argentine ants, native plants may also decline. This is a major concern in Haleakala National Park, Hawai’i, where Argentine ants are encroaching upon the habitat of the endemic giant silversword (Argyroxiphium sandwicense), which is pollinated by yellowfaced bees (Hylaeus spp.). It is feared ant predation on bee larvae will decimate the native bee. Competition between Argentine and native ants for food and habitat in California has affected the coastal horned lizard (Phrynosoma coronatum), which has a diet specializing on native harvester and carpenter ants. The loss of native ants has contributed to the decline of this once-common lizard. Decreases in the numbers of the native desert shrew (Notiosorex crawfordi) are also attributed, in part, to the presence of the Argentine ant. Argentine ants can be serious pests in commercial apiaries. Ants invade honey bee (Apis mellifera) hives, causing the bees to abandon it. The ants then remove the honey and bee larvae to their own nest. They can destroy 1–2 hives a day and soon overwhelm an entire bee yard. This ant has been nominated as by IUCN as among “100 of the ‘World’s Worst’ invaders.” Management. Once a colony is established, it is difficult if not impossible to eradicate it. Chemical controls such as DDT, chlordane, and dieldrin that once helped control ant populations are no longer legal to use in the United States. Bait traps can help, since the poison works slowly and ants bring it back to their nests, where it will kill all workers and queens. Prevention, through the inspecting of cargo and refuse, sealing cracks and other points of entry to buildings, and maintaining landscapes that offer no nest sites, coupled with swift action to eliminate any new infestations, is the most effective management strategy to limit the further spread of the Argentine ant.

Selected References Krushelnycky, Paul, Andrew Suares, and IUCN/SSC Invasive Species Specialty Group (ISSG). “Linepithema humile (Insect).” ISSG Database, 2006. http://www.issg.org/database/species/ ecology.asp?fr=1&si=127.

ASIAN LONGHORNED BEETLE n 113 Sarnat, E. M. “Linepithema humile.” PIAkey: Identification Guide to Ants of the Pacific Islands, Edition 2.0, Lucid v. 3.4. USDA/APHIS/PPQ Center for Plant Health Science and Technology and University of California–Davis, 2008. http://keys.lucidcentral.org/keys/v3/PIAkey/Fact_Sheets/ Linepithema_humile.html. Spring, Joe. “Argentine Ant (Linepithema humile) (Mayr, 1868).” Introduced Species Summary Project, Columbia University, 2004. http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/ inv_spp_summ/Linepithema_humile.html. Westervelt, David, and Eric T. Jameson. “Argentine Ant, Liniepithema humile Mayr (Hymenoptera: Formicidae).” Florida Department of Agriculture and Consumer Services, 2009. http:// www.doacs.state.fl.us/pi/pest_alerts/liniepithema_humile.html.

n Asian Longhorned Beetle Also known as: ALB Scientific name: Anoplophora glabripennis Order: Coleoptera Family: Cerambycidae Native Range. East Asia: It is widely distributed in China from Sichuan and Gansu provinces north and east to the vicinity of Beijing. It is also found on the islands of Hainan and Taiwan, throughout Korea, and in Japan. Distribution in the United States. The major infestations of Asian longhorned beetles are in urban trees in Brooklyn, Queens, Manhattan, Long Island, Staten Island, and Prall’s Island, New York; and in suburban Chicago. They have also been found in Hoboken, Jersey City, and Middlesex/Union counties, New Jersey; and in and around Worcester, Massachusetts. Description. The adults are large, glossy black beetles with irregular white spots on the wing covers (elytra). The scutellum, a small triangular plate between the attachment points of the forewings, is black. The antennae are longer than the body and marked with distinct black and white bands. Their bodies are 0.75–1.0 in. (20–35 mm) long and 0.25–0.5 in. (6–12 mm) wide. Adults are seen in the open from late spring into fall. The presence of Asian longhorned beetles is often recognized by signs on infested trees. Shallow oval borings in the bark of trees ooze sap. Sawdust-like debris collects at the base of trees or in the crotches of large branches. Circular holes the width of an adult are the exit holes of newly emerging beetles. Eggs are off-white and oblong, with slightly concave ends. They are 0.2–0.3 in. (5–7 mm) long. Larvae are pale yellow elongate grubs that reach lengths of nearly 2.0 in. (50 mm) before pupating. The pupae are off-white and about 1.2–1.3 in. (30–33 mm) long and 0.4 in. (11 mm) wide. All of these life-cycle stages are hidden deep inside living trees. Related or Similar Species. The whitespotted sawyer (Monochamus scutellatus), a native beetle found in most forested areas of the United States, is about the same size as the Asian longhorned beetle and also has long antennae. The body, however, is a dull or bronzed black, and the antennae are only faintly banded. The scutellum is white. Larvae are very similar to those of the Asian longhorned beetle. Whitespotted sawyers infest conifers, whereas Asian longhorned beetles prefer hardwoods. Another large native long-horned beetle is the boldly black-and-white cottonwood borer (Plectrodera scalator) of the eastern United States and the Great Plains. Its antennae are solid black and equal in length to the body. Larvae dwell in and near the roots, and pupation takes place below ground level in roots; therefore, no exit holes appear in tree trunks or branches.

114 n INVERTEBRATES (INSECTS) Introduction History. Asian longhorned beetles were first reported in the United States in the Greenpoint section of Brooklyn, New York, in 1996, although they may have been present but undetected for 10 years before then. They probably arrived in wooden pallets or other solid-wood packing materials with pipes that were brought in from China in the late 1980s for a sewer project. From Brooklyn, they spread to Amityville on Long Island, Queens, and Manhattan. The introduction to Long Island was the result of a tree care company inadvertently disposing contaminated wood from Brooklyn at several locations. A separate introduction gave rise to the population in Chicago, first reported in 1998. Asian longhorned beetles showed up in Jersey City, New Jersey, in 2002 and had expanded their distribution to other towns (Woodbridge and Rahway) by 2004. They appeared on Staten and Prall’s islands, Top: Asian longhorned beetles are native to eastern China, Korea, Japan, New York, in 2007, and in and Taiwan. Bottom: Asian longhorned beetles infest urban trees in and Worcester, Massachusetts, in around Chicago, Illinois; the boroughs of New York City; New Jersey; 2008. Live beetles continue to and Worcester, Massachusetts. be discovered at ports and warehouses in various states. Local dispersal from primary sites of infestation is most likely aided by the transport of infested firewood by vacationers, hunters, and others. Larvae hidden deep inside trees may be accidentally moved in live trees and cut timber as well. On their own, Asian longhorned beetles disperse very slowly. They were found exclusively on trees in cities and towns until 2008, when they were discovered in natural forests outside Worcester, Massachusetts. Habitat. Asian longhorned beetles usually infest urban broadleaf deciduous trees, but since 2008, they have been found in natural hardwood forests. Diet. Asian longhorned beetles differ from most other members of their family by eating the living wood of at least 18 species of broadleaf tree. (Most temperate-zone long-horned beetles have one preferred host and feed on dead and dying trees.) Maples (Acer spp.) are preferred, but Asian longhorned beetles have been reported to attack horse-chestnuts and buckeyes (Aesculus spp.), willows (Salix spp.), ash (Fraxinus spp.), birches

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A. Adult Asian longhorned beetle. (Donald Duerr, USDA Forest Service, Bugwood.org). B. Asian longhorned beetle larvae. (Michael Bohne, Bugwood.org.)

(Betula spp.), and sycamores (Platanus spp.). Larvae eat healthy cambium, phloem, and xylem, forming long tunnels in the sapwood and heartwood of host trees. Life History. In both New York and Chicago, adults reportedly emerge from pupae between July and October and bore their way through the bark of the host tree. This activity leaves telltale piles of frass and dime-size circular holes in the bark. The beetles usually fly only 150–250 ft. (50–70 m) away from the tree where they hatched. They feed on the bark of twigs on a new host tree for 2–3 days and then mate somewhere on the trunk or branches. The female chews a shallow, oval cavity into the cambium in which she lays a single egg; she will repeat this process 25–90 times. In 10–15 days, the eggs hatch into larvae that feed at first in the cambium but soon tunnel 4–12 in. (10–30 cm) deep into the tree. The larvae metamorphose into pupae and, about 18 days later, into adults inside the tunnels. Eggs, larvae, and pupae are able to overwinter if necessary. Adults remain active until late fall and then die. The life cycle is completed in 12–18 months. Impacts. Large numbers of larvae infesting a tree weaken the host. Their tunneling girdles the tree, and dieback of the crown becomes noticeable. Weakened branches can break in strong winds. Ultimately, the tree dies. The egg-laying cavities and exit holes joined to a gallery of tunnels inside the tree also open the host tree to infections and infestations of other kinds. Control efforts have resulted in the destruction of thousands of shade and ornamental trees in New York and Chicago. There is concern that if let loose in the broadleaf deciduous forests of New England, the Asian longhorned beetle could become a pest on the scale of gypsy moths (see Insects, Gypsy Moth) or chestnut blight (see Fungi, Chestnut Blight Fungus). Economic impacts in urban areas—where the beetles could rival Dutch elm disease (see Fungi, Dutch Elm Disease) in changing urban landscapes—involve diminished aesthetics and declining property values. Timber, maple syrup, nursery, and tourist industries are threatened in New England and elsewhere. Management. The chief legal and effective way in the United States to deal with urban infestations is to cut down all trees known to host the beetle, chip and burn the wood, and grind out the stump. The trees that are removed are replaced with nonhost species. Infested areas are quarantined, and firewood, tree trimmings, and other tree by-products

116 n INVERTEBRATES (INSECTS) are prohibited from being transported out of the area. Contact insecticides are of little value, because much of the life cycle of the beetle is spent inside the tree where sprays cannot reach it. Systemic insecticides that can be taken up by the roots and distributed into stems and foliage have some potential, as does the application of parasitic fungi in bands on tree trunks to control adult beetles. The Animal and Plant Health Inspection Service (APHIS) of the U.S. Department of Agriculture has inspectors at key ports of entry to check for beetle-infested cargo, targeting especially shipments from China with solid-wood packing materials. Since 1998, all such material is required to be treated prior to shipment to the United States, and compliance has been exceptionally high. Federal quarantines were imposed in Chicago, New York, and New Jersey. In quarantine areas, only arborists certified to remove Asian longhorned beetles are allowed to cut down infested trees. No wood from the area can be used, moved, or disposed of without an inspection permit. New trees to be planted should be nonhost species. The quarantine zones in Hoboken and Jersey City, New Jersey, were deregulated in 2005; and the quarantine in Chicago was lifted in 2006. However, the quarantine area in the Middlesex/Union County area of New Jersey was expanded when new trees infested with the beetle were discovered. In July 2008, a new regulated area was established in Worcester, Massachusetts, that covers 62 sq. mi. (160 km2). Visual surveys of trees and other means of early detection of and rapid response to new infestations are underway to attempt to prevent the spread of this pest into the natural forests of Massachusetts and surrounding states.

Selected References “Asian longhorned beetle.” University of Vermont, 2005. http://www.uvm.edu/albeetle/index.html. Cavey, Joseph F. “Anoplophora glabripennis.” National Information Center for State and Private Forestry, U.S. Forest Service, 2000. http://spfnic.fs.fed.us/exfor/data/pestreports.cfm?pestidval=53&lang display=english. Muruetagoiena, Tamara. “Asian Longhorned Beetle (Anoplophora glabripennis).” Introduced Species Summary Project, Columbia University, 2004. http://www.columbia.edu/itc/cerc/danoff-burg/ invasion_bio/inv_spp_summ/Anoplophora%20glabripennis.html.

n Asian Tiger Mosquito Scientific name: Aedes albopictus Synonym: Stegomyia albopictus Order: Diptera Family: Culicidae Native Range. Asia. The Asian tiger mosquito occurs naturally from tropical Southeast Asia north through China, South Korea, and Japan, and on islands in the Pacific and Indian oceans, including Madagascar. Distribution in the United States. Asian tiger mosquitoes are established in 26 states in the continental United States and in Hawai’i. Primarily a species of the Southeast, discontinuous outlying populations are recorded as far north as Minnesota and as far west as Nebraska, Kansas, Oklahoma, and Lubbock and Val Verde counties in Texas. On the East Coast, the northern limit is currently New Jersey, but that could change with a warming climate. Description. The adult is a small mosquito with a black body and conspicuous silverywhite bands on the legs and feelers (palpus). A single white stripe runs along the back and

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head. Males are smaller than females and have feathery antennae and mouthparts modified for nectar-feeding. The female has unadorned feelers and a long proboscis adapted to biting and feeding on blood. As in all members of the genus Aedes, the abdomen narrows to a point. Adults are a little less than 0.25 in. (5 mm) long. The wormlike larvae, or “wigglers,” are easily disturbed by vibrations or a passing shadow and quickly descend to the bottom of the water container in which they live. They must periodically rise to the water surface to obtain oxygen through a somewhat inflated-looking breathing siphon. Fully grown wrigglers are about 0.25 in. (5 mm) long. The pupae are dark brown and curled into the shape of a comma. When disturbed, these “tumblers” roll end over end through the water. Related or Similar Species. The yellow fever mosquito, Aedes eagypti, like the Asian tiger mosquito, is active by day and breeds in water held in contain- Top: The Asian tiger mosquito’s native range extends from Southeast Asia ers. Its hind legs also bear white to Japan and includes islands in the Pacific and Indian oceans. (Adapted bands. In the field, the yellow from map by Gando, http://en.wikipedia.org/wiki/File:Albopictus fever mosquito is distinguished _distribution_2007.png.) Bottom: Asian tiger mosquitos are currently by the lyre-shaped pattern of established in 27 states. (Adapted from “Distribution of Aedes albopictus in the United States, by County, 2000.” Centers for Disease Control and white scales on its back and the Prevention, Division of Vector-borne Infectious Diseases. www.cdc.gov/ white scales on the head of the ncidod/dvbid/arbor/albopic_new.htm.) female on a structure above its proboscis. In female Asian tiger mosquitoes, this structure is black. The yellow fever mosquito originated in Africa and probably came to the New World on ships in the early days of trans-Atlantic trade and exploration. Introduction History. Asian tiger mosquitoes probably arrived in Hawai’i soon after World War II. Their first verified occurrence in the continental United States, indeed in the New World, came in 1985 in Houston, Texas. It was accidentally transported from Japan in used tires imported for recapping. During the 1980s, importations of used tires increased, and Asian tires were preferred because of their high rubber content. They arrived in containers that were inadequately inspected at the ports of entry. The first

118 n INVERTEBRATES (INSECTS) discovery of the mosquito in Maryland occurred in 1987 at a tire processing plant in Baltimore. The movement of used tires within the United States dispersed the insect to other eastern and midwestern states. Used tires are typically stored outdoors for long periods of time, and those that cannot be used for recapping often end up in illegal tire dumps. In both instances, they collect rainwater and become prime Asian tiger mosquito breeding Asian tiger mosquito (male). (Susan Ellis, Bugwood.org.) grounds. In California, Asian tiger mosquitoes were discovered in 2001 in containerized shipments of lucky bamboo (Dracaena sp.) from southern China. The popular ornamental plants had been transported in standing water so they would survive the long voyage. The mosquitoes have been locally dispersed in moist vegetation and water containers, including cemetery flower pots. In several Florida counties, the mosquitoes were first found in cemeteries where fresh-cut flowers were placed at grave sites in plastic floral baskets. When the flowers died, they were discarded; however, the baskets were reused, often at different cemeteries. Eggs laid when flowers were fresh and standing in water in one cemetery would hatch later in another when water was again added. Habitat. The Asian tiger mosquito likely evolved in forests where it could breed in treeholes and in epiphytes and other places where water pooled. It still prefers the shade of densely vegetated areas, but exploits artificial containers in urban and suburban areas for breeding sites. It reproduces in bird baths, cemetery flower pots, empty soda cans, and other abandoned containers that hold water, but it is associated especially with old tires that collect water and organic-rich debris. The water only needs to be 0.25 in. (5–6 mm) deep. Northern range limits may be set by cold temperatures (daily mean temperatures in January of 32°F or 0°C) that prevent overwintering of eggs. Initially in the United States, the southern limit was established by summer day lengths shorter than 13.5 hours, but the species has overcome that controlling factor. Diet. Asian tiger mosquitoes acquire energy by feeding on nectar. The females, however, need protein to produce eggs, and they feed also on blood. Humans are the chief host, but the females will feed on a variety of other mammals including dogs and cats, and on birds, reptiles, and amphibians. They generally feed at ground level, biting people around the ankles and knees. The larvae are filter-feeders, consuming particulate organic debris and bacteria. Life History. Mating occurs soon after adults emerge from pupae. The female mates only once and stores sperm for future egg production. A female feeds on blood for 4–5 days before laying eggs. She then deposits 40–150 eggs on the sides of containers just above water level. She will continue a weeklong cycle of feeding on blood and laying eggs for the

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remainder of her life. The eggs do not hatch until water level rises and covers them. Eggs may overwinter and not hatch until the following spring or summer, when they become flooded by water warmer than 60° F (15.5° C). The wriggling larvae develop through four instars and change into pupae about 10 days after hatching. Unlike many other insects, mosquito pupae are mobile, but they do not feed. Adults emerge from the pupae 10–14 days later. Adult mosquitoes live several days to a few weeks depending upon the weather. The lifespan is reduced during hot, dry spells. During their lives, adults rarely move more than a few hundred yards (or meters) from the container in which they hatched. Impacts. The arrival of the Asian tiger mosquito raised major concerns of its potential as a vector for virus-based dengue fever. Dengue fever is a disease of the tropics. It once posed a sporadic health problem in southern states, but was eradicated in the United States in the 1940s. However, dengue fever is common in the Caribbean and tropical South and Central America, and could easily be reintroduced. A warming climate might enhance its ability to spread. It now appears that the Asian tiger mosquito is less likely than its close relative, the yellow fever mosquito, to transmit the dengue fever virus from human to human and cause major outbreaks of the disease. This is because the Asian tiger mosquito has multiple mammalian, avian, and reptilian hosts and is not restricted to a diet of human blood as is the yellow fever mosquito. If, after biting a human, the mosquito moves on to a bite another type of host, transmission of the virus is halted. In laboratory studies, the Asian tiger mosquito has proved to be a competent vector for a number of other viruses, including eastern equine encephalitis, yellow fever, West Nile disease (see Microorganisms, West Nile Virus), LaCrosse encephalitis, St. Louis encephalitis, and western horse encephalitis. It is also a carrier of the nematode known as canine heartworm. Field populations have been found to carry eastern equine encephalitis virus and West Nile virus, but so far, no evidence exists that this mosquito has transmitted disease to any person. The Asian tiger mosquito’s greatest impact has been as an extreme nuisance. It is much more annoying than the yellow fever mosquito. An aggressive and persistent biter that feeds during the day, it tends to rest in shrubs in shady areas, where people also seek relief from the summer sun. The female interrupts her feeding to bite the same person several times and, because of her agility, is difficult to swat. She injects an anticoagulant from their salivary glands that causes the bite to swell and itch. Sometimes the itch may last for a week. The Asian tiger mosquito has displaced the yellow fever mosquito from many areas in which the distribution areas of the two overlapped. Management. The best defense against the Asian tiger mosquito is for individuals to remove potential breeding sites, such as old tires, empty buckets, or other containers that could fill with rainwater. Bird baths and wading pools should be emptied at least once a month. Roof gutters should be kept free of debris that would dam up water. The larvae can be killed with applications of the bacterium Bti (Bacillus thuringiensis israelensis). Adults are not readily trapped by contrivances that attract other mosquitoes, and they are resistant to many insecticides. Biological controls include stocking predators of the larvae such as mosquitofish (Gambusia spp.; but see Fish, Mosquitofish) and developing a genetically engineered male that will pass a lethal gene to its female offspring. Since 1988, the U.S. Public Health Service has required that all used tires imported into the United States from areas known to have Asian tiger mosquitoes be dried, cleaned, and fumigated.

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Selected References “The Asian Tiger Mosquito in Maryland.” Maryland Department of Agriculture, n.d. http:// www.mda.state.md.us/plants-pests/mosquito_control/_asian_tiger_mosquito_md.php. Crans, Wayne J. “Aedes albopictus (insect).” ISSG Database, IUCN/SSC Invasive Species Specialist Group (ISSG), 2009. http://www.issg.org/database/species/ecology.asp?si=109&fr=1&sts. Crans, Wayne J. “The Asian Tiger Mosquito in New Jersey.” Fact Sheet. Rutgers Cooperative Research and Extension, New Jersey Agricultural Experiment Station, Rutgers, the State University of New Jersey, 1996. http://njaes.rutgers.edu/pubs/download-free.asp?strPubID=FS845. O’Meara, G. F. “The Asian Tiger Mosquito in Florida.” Entomology and Nematology Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, 2005. http://edis.ifas.ufl.edu/mg339. Rios, Leslie, and James E. Maruniak. “Featured Creatures: Asian Tiger Mosquito.” University of Florida, 2008. http://entnemdept.ufl.edu/creatures/aquatic/asian_tiger.htm.

n Brown Marmorated Stink Bug Also known as: Yellow-brown stink bug; BMSB Scientific name: Halyomorpha halys Family: Pentatomidae Native Range. East Asia: China, Japan, Korea, and Taiwan Distribution in the United States. This rapidly spreading bug was reported in California, Delaware, Maryland, Missouri, New Jersey, New York, North Carolina, Oregon, Pennsylvania, Tennessee, Virginia, West Virginia, and the District of Columbia by 2010. Description. Adults have the shield body shape typical of all stink bugs. The back is a marbled (marmorated) brown, and the underside a lighter tan color. Small round depressions on the head and first segment of the thorax (the pronotum) are coppery or bluish metallic in color. The edges of the pronotum are smooth, unlike the jagged margin of native stink bugs of the genus Brochymena. The next-to-last segment of the antennae bears pale bands, a distinguishing characteristic. The abdominal segments that extend beyond the wings have alternating bands of black and white; and the brown legs have faint light bands. Scent glands are located between the first and second pair of legs on the underside of the thorax. Adults are about 0.5 in. (12–17 mm) long and almost as wide. Immatures or nymphs develop through five stages or instars. The first instars have yellowish-red abdomens with black bars and dark red eyes; they look like ticks and are about 0.09 in. (2.4 mm) long. Relatively inactive, they tend to remain clustered near the hatched egg mass. Successive instars become larger and more closely resemble adults. Their legs and antennae are black with white bands. The final, fifth instar has a whitish abdomen with red spots and is about 0.47 in. (12 mm) long. Knobs protrude in front of the scent glands on the underside, and spines occur on the legs, in front of the eyes, and on the sides of the thorax. The pale green eggs are elliptical and measure about 0.04 in. (1 mm) in diameter. They are usually found on the underside of leaves in masses of 20 to 30. Related or Similar Species. Brown marmorated stink bugs are easily confused with native species of stink bug, including the brown stink bug (Euschitus servus) and the green stink bug (Acrosternum hilare); with rough stink bugs (Brochymena spp.); and some leaf-footed or squash bugs (Family Coreidae). The Western conifer seed bug (Leptoglossus occidentalis) also invades buildings in the autumn in order to winter over, but it can be distinguished from the BMSB by the flattened structures on the lower segments of its hind legs.

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Introduction History. This bug was accidentally introduced in packing materials to Allentown, Pennsylvania, where it was first collected in September 1998. It may have been present for a couple of years before it was discovered and identified. In 2000 and again in 2002, it was collected in New Jersey and, soon afterward, appeared in Delaware, Connecticut, and New York. In 2005, an established population was documented in Oregon. The stink bug has become established in many places on the East Coast of the United States and continues to expand its range. By 2009, it was established in Maryland, Virginia, and West Virginia and had been collected in California, Florida, Mississippi, Missouri, North Carolina, Ohio, Tennessee, and Washington, D.C. It is suspected that they are moving across the country in motor vehicles. Habitat. Originally, populations were restricted to urban and suburban landscapes where Top: The brown marmorated stink bug is native to East Asia. Bottom: they were associated with orna- This new invader was reported in 12 states and the District of Columbia mental plants, garden crops, by 2010. and fruit and shade trees. They have since expanded into agricultural areas, including orchards. Brown marmorated stink bugs seek winter shelter in buildings, entering in the fall through any small opening. They remain dormant much of the winter and leave houses and other buildings in the spring to reproduce and forage outside. Diet. These bugs are sucking insects that feed on a wide variety of plants. They pierce fruit and leaves with specially adapted mouthparts and withdraw plant juices. Nymphs feed on fruits and seed pods. They are known to eat apples, peaches, pears, blackberries, tomatoes, green peppers, beans, sweet and field corn, and soybeans. Among ornamentals, they attack shade trees such as Norway maple (Acer platanoides) and ornamentals such as princess tree (Paulownia tomentosa), butterfly bush (Buddleia spp.), Rugosa roses (Rosa rugosa), and honeysuckle (Lonicera sp.) Life History. Mating takes place in early summer, approximately two weeks after adults emerge from hibernation. Egg-laying begins in early summer and will continue through

122 n INVERTEBRATES (INSECTS) September in the Mid-Atlantic states. The female lays new egg masses on the undersides of leaves about once a week throughout the summer. The eggs hatch in four or five days and first instar nymphs usually stay near their egg mass until after the first molt. Each nymphal stage lasts about one week and is followed by a molt that produces the next instar. About two weeks after the final molt, the adults are sexually mature. Only one generation appears to be produced each The brown marmorated stink bug is rapidly expanding its range year. However, since several in the eastern United States. (David R. Lance, USDA APHIS PPQ, generations are produced each Bugwood.org.) year in the subtropical regions of its native range, the same may be expected when the stink bug becomes established in the Southeast. Adults live several years, and a single female may lay up to 400 eggs during her lifetime. Impacts. Brown marmorated stink bugs are primarily nuisances in homes and other buildings, where they congregate in autumn and then overwinter. On warm days, they may rouse from hibernation and fly around, and in the spring, they fly to windows and doorways as they try to leave the premises. The bugs do no structural damage, do not lay eggs inside buildings, and are not known to carry any diseases. However, when crushed, they secrete a most unpleasant odor from their scent glands. The stink bug can damage ornamental and garden plants and is becoming an agricultural pest in apple and peach orchards. Their feeding methods causes puckering, scarring, and deformation of fruits—a condition known as cat facing, which renders them unfit for sale as fresh market items. The fruits may still be processed, however, for juices, jams, sauces, and the like. Leaf-stippling will occur on leaves. The spread of the bug could threaten commercial apple, peach, and soybean crops. Damage to orchard crops has already been reported in Maryland and West Virginia. Management. Preventing stink bugs from getting into buildings is the best line of defense. All potential cracks and crevices around windows and doors, chimneys, siding, fascia, and holes through which wiring passes should be caulked. Screens on windows and doors and on roof vents and weep holes should be kept in good repair. Insecticides applied around such openings in early fall when the bugs swarm and try to gain entry have shortterm effects. Most degrade rapidly. A professional exterminator should be consulted for the best and safest results. With light infestations, individual bugs can be swept into a pail of water. Once the insects are indoors, vacuuming individual stink bugs is the best remedy. Empty vacuum bags immediately to prevent a buildup of the stench injured, dying bugs exude. Do not spray insecticides in an attempt to kill bugs hiding in the house. The dead bugs will attract other pests such as carpet beetles, which will later feed on woolen items, dry goods, and other natural materials.

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Spot treatment of garden plants with insecticides will reduce the damage from these insects.

Selected References Day, Eric R., and Dini Miller. “Brown Marmotated Stink Bug, Homoptera: Penatomidae: Halyomorpha halys.” Virginia Cooperative Extension, 2009. http://pubs.ext.vt.edu/2902/2902-1100/2902 -1100.html. Gyeltshen, Jamba, Gary Bernon, and Amanda Hodges. “Common Name: Brown Marmorated Stink Bug.” Featured Creatures, Department of Entomology and Nematology, University of Florida, 2010. http://entnemdept.ufl.edu/creatures/veg/bean/brown_marmorated_stink_bug.htm. Jacobs, Steve. “Brown Marmorated Stink Bug,” Entomological Notes. College of Agricultural Sciences, Cooperative Extension, Pennsylvania State University, 2010. http://ento.psu.edu/extension/fact sheets/brown-marmorated-stink-bug. MIPSP. “Brown Marmorated Stink Bug.” Massachusetts Introduced Pests Outreach Project, 2008. http:// www.massnrc.org/pests/pestFAQsheets/brownmarmoratedstinkbug.html.

n Common Bed Bug Also known as: Bedbug, chinche, mahogany flat, redcoat, wall louse Scientific name: Cimex lectularius Order: Hemiptera Family: Cimicidae Native Range. Uncertain: possibly eastern Mediterranean. May have originated as a parasite of bats that transferred to humans in caves occupied by nomadic Stone Age peoples. Bed bugs apparently did not become a problem until people began to live in villages and cities. Distribution in the United States. Throughout. Description. Adult bed bugs are small, oval, wingless insects. Before they feed, bed bugs are flat and brown, but when engorged after a blood meal, they are swollen and dark red. Eyes are dark. The upper surface of the first segment of the thorax (the prothorax) forms a wide collar-like plate that curves slightly around the broad head. Antennae are prominent and have four segments. The abdomen has 11 segments. Before feeding, adult bed bugs are about 0.25 in. (4–9 mm) long and 0.06–0.1 in. (1.5–3 mm) wide. Newly hatched nymphs are the size of poppy seeds and colorless. Later nymphal instars are smaller, paler versions of the adult. They become bright red after feeding. The creamcolored oval egg is about 0.04 in. (1 mm) long. Bed bugs are rarely seen. Evidence of their presence develops in areas where they congregate and hide during the daytime. Such harborages will accumulate dark spots and staining from their feces, eggs, and eggshells, shed skins of maturing nymphs, and adult bugs. Red stains on bedding and mattresses occur when engorged bed bugs are accidentally crushed by their sleeping human hosts. Bed bugs do exude a distinct odor, variously described as resembling crushed coriander, rotting raspberries, or a sweet musty smell; but only when infestations are heavy can this be detected by people. Bed bug bites are indicated by a patch of redness on the skin with a darker raised welt in the center. However, half of the people who are bitten experience no reaction; and among those who do show visible signs, the size and itchiness of the bite varies greatly. Bites usually occur on the exposed skin of the face, neck, arms, and hands and may be clustered or occur in a line. Identification of the presence of bed bugs from the bites alone is problematic.

124 n INVERTEBRATES (INSECTS) Related or Similar Species. Most other bed bug species prefer other mammals and birds as hosts. C. lectularius prefers humans, but will feed on bats, cats, dogs, and rodents as well as chickens and other birds. In tropical regions of the world, C. hemipterus is the more common parasite of humans. It has a noticeably narrower prothorax than C. lectularius. (The bed bug found in Hawai’i is C. lectularius.) Bed bugs could be confused with small ticks or cockroaches. Their bites can be mistaken for those of mosquitoes, fleas, and spiders. Introduction History. The dispersal history of bed bugs is not well documented, but they became widespread in the temperate regions of the Northern Hemisphere during the colonial period and likely came to the United States in the 1700s when infestations on sailing ships out of Europe were notorious. They were known from Greece as early as 400 BC but were not mentioned in accounts Top: The actual origins of the common bed bug remain unknown, but it from Germany until the elevmay derive from the eastern Mediterranean. Bottom: Common bed bugs enth century or from France are found throughout the United States. until the thirteenth century. Although first noted in England in 1583, they did not become common until 1670. Presumably, sometime after that they made their way to what is now the United States. They had appeared in Jamaica, another British colony, by 1726. In the early twentieth century, bed bugs were so common that they were deemed one of the top three household pests. The widespread use of DDT after World War II essentially eradicated bed bugs from the United States and other developed countries in the 1950s. However, bed bug populations quickly developed resistance to DDT, and the use of the pesticide was banned altogether in the United States in 1972 because of its deleterious effects on birds. In the 1990s, after an absence of nearly 50 years, bed bugs began a rapid increase, not only across the United States but in all the industrialized countries of the world. Once associated with poverty and underdevelopment, bed bugs now also occupy high-end hotels and residences. The resurgence may be a consequence of increases in international travel and immigration; the development of pesticide resistance, especially to pyrethroids; and

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A. Adult bed bug. (James D. Young, USDA APHIS PPQ, Bugwood.org.) B. Bed bug eggs. (Mohammed El Damir, Pest Management, Bugwood.org.)

changing control practices for other vermin, such as cockroaches and ants, that no longer rely on broad-spectrum, persistent, and highly toxic pesticides, but focus on safer methods of bait-trapping. One study has traced the origin of the latest outbreak of bed bugs to poultry facilities in Arkansas, Delaware, and Texas. Workers could have unknowingly carried the pests home or elsewhere when they left the workplace. Another study suggests that recent infestations began in the Northeast and spread south and west from there. The last states to report major infestations were Hawai’i, Oregon, and Washington. Habitat. These bugs occur where people sleep. All they need are a source of blood and a place to hide. They tend to hide close to where they feed. Their flat shape and small size allow them to congregate in tiny cracks and crevices. They prefer dry, rough surfaces such as wood and paper and avoid wet and hard surfaces such as stone, metal, and plaster. Favored sites include the seams of mattresses, box springs, bed frames, and cracks in molding. In hotels, they are often first found behind headboards. They may be found among items stored under beds; along and under the edges of wall-to-wall carpeting; behind picture frames, switch plates, and outlets; behind wallpaper; and in phones, smoke detectors, and televisions. In large infestations, they will spread to upholstered furniture and among clutter accumulated in closets. While bed bugs were once associated in the popular mind with urban poverty and filth, this is not the case. Today’s outbreaks commonly occur in fine hotels, vacation resorts, and cruise ships as well as in hospitals, college dormitories, and well-maintained apartment buildings and single-family residences. Diet. Common bed bugs are obligate feeders on blood. Humans are their preferred hosts. They feed mainly at night while their hosts are asleep. They respond to warmth and carbon dioxide to locate their blood meal. Finding exposed skin, they pierce it with their mouthparts and inject their saliva, which contains an anticoagulant and numbing compound. A full meal takes 5–10 minutes. Typically during that time, a bed bug makes a row of three bites: “breakfast,” “lunch,” and “dinner.” Adults may live several months without feeding. Life History. After mating, a female lays 2–3 eggs per day in cracks and crevices. The female continues to lay throughout her lifetime, which may last 6–12 months, producing a total of 200–500 eggs. At room temperature (68°F or 20°C), nymphs hatch out in 1–2 weeks and immediately begin to feed. Bed bugs undergo incomplete metamorphosis in that the

126 n INVERTEBRATES (INSECTS) nymphs are simply tiny adults. Each of the five juvenile or nymphal states requires a blood meal in order to molt into the next stage. Full maturation takes from 9 to 18 weeks. Several generations can be produced in a year. Impacts. Bed bugs are not known to transmit diseases to humans. In minor infestations, they are chiefly an annoyance and embarrassment. Their bites cause itchiness and inflammation in some people. Scratching the bites might result in secondary infections. The occurrence of bed bugs can result in lawsuits against landlords and other property owners obligated to provide safe and habitable conditions for tenants. Management. Eradication, especially of major infestations in multiple-unit buildings, is difficult and requires the assistance of experienced, professional pest control companies in administrating an integrated pest management program. Although the media has recently tried to blame EPA and its ban of persistent pesticides for the current resurgence in bed bugs, many populations had already developed resistance to DDT and other organophosphates in the 1950s and 1960s as well as to the pyrethroids used in their place. Today, few over-the-counter insecticides registered for use in homes are effective against bed bugs, but licensed pest control operators do have some options available. Furthermore, some companies are using specially trained dogs to help locate infestations. Several nonchemical treatments exist that help control minor infestations. Careful and repeated vacuuming of places where bed bugs like to hide can physically remove bugs from sites that a high suction wand can reach. Heat (temperatures above 120°F or 49°C) kills eggs, nymphs, and adults. Clothes and bedding can be washed in hot water. Backpacks, toys, or shoes and the like—dry or wet—can treated in a clothes dryer set at medium-tohigh heat for 20 minutes. Larger items such as suitcases can be put in plastic bags and set in the sun or in a closed car parked in the sun for a day. Freezing temperatures will also kill bed bugs, but items must be left outside in winter or in a freezer for several days for the cold to be effective. Preventing an infestation is paramount in the fight against bed bugs. Bed bugs are transported from place to place on luggage, clothing, boxes, secondhand furniture and mattresses. They spread through buildings by crawling out entry ways and through holes in walls and ceilings. Caulking cracks and crevices and sealing or removing loose wallpaper will help deter them, but careful inspection of items brought into the house is also important. This is especially true for purchasers of secondhand beds and sofas and frequent travelers. In hotels, keep suitcases off the floor and on hard surfaces such as luggage stands and table tops. Put clothing in disposable plastic bags and directly into a washing machine and/ or dryer upon arrival home. Remove clutter from floors and monitor or eliminate any other potential bed bug harborages. Keeping sheets and blankets from contacting the floor by tucking them in and placing the legs of a bed frame in a small dish of mineral oil will keep bed bugs from crawling up into a bed. Usually a combination of techniques is required, as is the cooperation of all inhabitants of a building. Frequent inspection of one’s surroundings will at the very least allow early intervention by a professional. Bed bug bites may be avoided by wearing pajamas that cover arms and legs. Insect repellents have not proven very effective deterrents, although mosquito netting impregnated with permethrin may help—until bed bugs develop resistance to that pesticide. Today’s rapid increase in bed bug populations is making them a major public health concern and instigating more research on ways to control and eradicate this long-neglected insect. New products such as the insecticide chlorofenpyr and the insect growth regulator hydroprene, though slow acting, seem to be effective. Still, no chemical means of control by itself can eliminate an infestation entirely.

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Anyone with a suspected infestation should contact a licensed pest control operator for confirmation and notify the public health department. Do not apply any insecticide or pesticide directly to a mattress or other surface that comes into direct contact with people or pets.

Selected References Anderson A., and K. Leffler. “Bed Bug Infestation in the News: A Picture of an Emerging Public Health Problem in the United States.” Journal of Environmental Health 70(9): 24–27, 2008. Brooks, Shawn E. “Bed Bug, Cimex lectularius Linneaus (Insecta: Hemiptera: Cimicidae).” Document EENY-140 (IN297), Featured Creatures, Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, 2009. https://edis.ifas.ufl.edu/in297. Centers for Disease Control and Prevention, U.S. Environmental Protection Agency. “Joint Statement on Bed Bug Control in the United States from the U.S. Centers for Disease Control and Prevention (CDC) and the U.S. Environmental Protection Agency (EPA),” 2010. http:// www.cdc.gov/nceh/ehs/publications/Bed_Bugs_CDC-EPA_Statement.htm. Pollack, Richard, and Gary Alpert. “Bed Bugs.” Harvard School of Public Health, 2005. http:// www.hsph.harvard.edu/bedbugs/. Potter, Michael F. “Bed Bugs.” ENTFACT-636, Department of Entomology, University of Kentucky College of Agriculture, 2010. http://www.ca.uky.edu/entomology/entfacts/ef636.asp. Staab, Tina. “The History of Bed Bugs.” eHow.com, 2009. http://www.ehow.com/about_5376204 _history-bed-bugs.html#ixzz0y7tJ0BxF.

n Emerald Ash Borer Also known as: EAB Scientific name: Agrilus planipennis Order: Coleoptera Family: Buprestidae Native Range. Emerald ash borers are native to northeastern China and adjacent areas of Mongolia and Russia, Korea, Japan, and Taiwan, where forests are composed of broadleaf trees closely related to those in the eastern United States. Distribution in the United States. This beetle currently occurs in Illinois, Indiana, Kentucky, Maryland, Michigan, Minnesota, Missouri, New York, Ohio, Pennsylvania, Virginia, West Virginia, and Wisconsin. Description. Adult emerald ash borers are small, metallic-green beetles. The slender, elongate bodies are about 0.5 in. (7.5–13.5 mm) long, males being somewhat smaller than females. When open, the wing covers expose a metallic-purplish-red abdomen. The segment just behind the head, to which the first pair of legs is attached, is wider than the head. Larvae are whitish with a brown head. Their abdomens have 10 segments, are flattened dorsoventrally, and end with a pair of brown pincers. Late stage larvae are about 1.0 in. (26–32 mm) long. Adults are active and seen in the open only from mid-May to September and usually only in the afternoons of warm, sunny days, making infestations difficult to detect. Early signs and symptoms that emerald ash borers have invaded a tree include jagged orange scars in the bark made by woodpeckers on the upper trunk and branches and a top-down thinning of the canopy and yellowing of leaves. Bark may split vertically where larval feeding galleries have been excavated beneath it. If the bark of infested ash trees is cut away, serpentine tunnels filled with

128 n INVERTEBRATES (INSECTS) a fine sawdust-like frass are the obvious signs that the beetles are present. With heavy infestations, as trees begin to die, they resprout from the roots. Related or Similar Species. A number of ash borers are native to the United States but are not similar in color, body shape, or shape of the exit hole. However, several metallic wood-boring beetles native to American forests are likely to be confused with emerald ash borers. Among them are the bronze birch-borer (Agrilus anxius) and the two-lined chestnut borer (Agrilus bilineatus), both of similar size and shape but not green; and the six-spotted tiger beetle (Cinindela sexguttata) and the caterpillar hunter (Calosoma scrutator), both of which are green but have distinctly different body shapes. Introduction History. The emerald ash borer was first confirmed in the United States in 2002 in Canton, Michigan. It probably had arrived at least 15 years earlier in wood packTop: Emerald ash borers are native to the broadleaf forests of northeastern ing materials coming from China, Korea, Japan, and Taiwan. (Adapted from “Native range of China. From Michigan, the beeemerald ash borer in Asia.” USDA Forest Service, Northern Research tle migrated to Ohio (2003) and Station. http://www.nrs.fs.fed.us/disturbance/invasive_species/eab/local Minnesota (2009). In 2003, it -resources/images/native_range.gif.) Bottom: The emerald ash borer was carried illegally to Prince currently affects ash trees in cities, suburbs, and forests in 13 states. George, Maryland, in nursery (Adapted from map by Cooperative Ash Borer Project, USDA Forest Service, 2010. http://www.emeraldashborer.info/files/MultiState stock originating in Michigan and sold in Maryland and _EABpos.pdf.) Fairfax County, Virginia. The emerald ash borer continues to be spread to other parts of infested states and to new states in live trees, green lumber, firewood, wood chips, and debris. It had arrived in Indiana by 2004; Upper Peninsula, Michigan, by 2005; Cook County, Illinois, by 2006; several counties in Pennsylvania by 2007, and at New River Gorge in Fayette County, West Virginia, by 2007. It was confirmed in Missouri and Wisconsin in 2008 and in Kentucky, Minnesota, and New York in 2009. Habitat. Emerald ash borers require ash trees. They survive in urban and suburban parks, yards, and roadways, woodlots, and natural broadleaf deciduous forests.

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A. Adult emerald ash borer. (Pennsylvania Department of Conservation and Natural Resources–Forestry Archive, Bugwood.org.) B. Emerald ash borer larva. (Pennsylvania Department of Conservation and Natural Resources– Forestry Archive, Bugwood.org.) C. Exit holes made by emerald ash borer. (Joseph O’Brien, USDA Forest Service, Bugwood.org.) D. Twisting tunnels or galleries made by emerald ash borer larvae. (Art Wagner, USDA APHIS PPQ, Bugwood.org.)

Diet. Emerald ash borers feed exclusively on trees of the genus Fraxinus. Adult beetles eat along the edges of leaves. Larvae eat phloem and xylem in the outer sapwood. They tend to prefer the upper trunks and branches of large trees. In the United States, green ash (F. pennsylvanica) and black ash (F. nigra) are more vulnerable to attack than white ash (F. americana) and blue ash (F. quadrangulata), but all ash species are at risk. Life History. Females deposit their eggs one by one in crevices in the bark or under flaps of bark on the trunk and branches of ash trees. Seven to 10 days later, the eggs hatch, and

130 n INVERTEBRATES (INSECTS) the larvae bore through the bark into the phloem to begin feeding. They feed for several weeks, creating ever wider, s-shaped tunnels in the outer sapwood as they grow. A single feeding gallery will range in length from 4 to 12 in. (20–50 cm). Feeding ends in the fall, and the prepupal larvae overwinter in shallow chambers about 0.5 in. (1 cm) deep in the outer sapwood or bark. The pupal stage begins in late April or May, and adults begin to emerge in late May, with peak emergence occurring from early to mid-June. Adults are able to fly immediately upon emerging and, although strong fliers, usually move less than 0.5 mi. (0.8 km) to find a mate and a new host tree. They will feed on the foliage for a few days while they mature, and then they mate. Females begin egg-laying after another week or two of feeding. Adult males survive about one month after emergence, females for about two months. Research in Michigan indicates that the life cycle is longer in healthy trees than stressed ones. In newly infested trees, many larvae overwinter in the earliest stage of development and feed during a second summer. In stressed trees, nearly all larvae overwinter in the late prepupal stage, and then pupate and emerge as adults the next summer. Impacts. Emerald ash borers kill all trees that they infest. Adult beetles do relatively little damage when they feed on the foliage. It is the larvae that are so destructive: they feed on phloem and interrupt the flow of nutrients through the tree, so the tree weakens and dies. The deaths of ash trees affect city and suburban landscapes, where they are planted as shade trees and ornamentals in parks and yards. In forests, their deaths mean a loss of browse, shelter, and seed that may be consumed by birds, small mammals, and insects. Although many dead or dying trees produce sprouts at the base, these too are attacked once they attain diameters of about 1 in. (0.5 cm). The demise of white ash across large swaths of eastern North America could result in the loss of forest biodiversity and have widespread impacts on habitat and watershed quality. In economic terms, trees valuable in the timber industry are being lost, and livelihoods based upon the sale of wood products such as lumber, mulch, and firewood are threatened. A special concern exists among some Native American groups who view black ash as a cultural resource because they use it in their basket making. Management. Containment rather than eradication is the main goal of management. The federal government (APHIS) and infected states set up quarantine zones in efforts to prevent the further spread of the emerald ash borer. Within each quarantine area, the movement of firewood, green lumber, ash nursery stock, and ash debris as well as all wood chips is restricted. As of March 2010, federal quarantine areas cover the entire states of Illinois, Indiana, and Ohio; all of the Lower Peninsula of Michigan; and parts of Kentucky, Maryland, Minnesota, New York, Pennsylvania, Virginia, West Virginia, and Wisconsin. Interstate movement of all firewood is prohibited, since it is difficult to distinguish ash from other hardwoods. Surveys of areas surrounding infected counties are conducted frequently to detect new infestations. Monitoring tools such as prism purple panel traps, baited with a lure and a nontoxic glue on the outer surfaces to catch any adult beetles attracted to the trap, are used. Experiments to see if a parasitic wasp can help control emerald ash borers are focusing on three tiny stingless wasps that lay their eggs in beetle larvae or eggs. In their native range in China, emerald ash borers are forest pests but do not have devastating effects, in part because Chinese ashes have evolved resistance to their attacks. Asian trees survive in Michigan, a state with a large infestation. It may be possible to hybridize American ashes and Chinese species and select for resistance as has been done with the American chestnut (Castanea dentata; see Fungi, Chestnut Blight Fungus) and American elm (Ulmus americana; see Fungi, Dutch Elm Disease).

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Selected References Bauer, Leah S., Therese M. Poland, and Deborah L. Miller. “Emerald Ash Borer.” Forest Disturbance Processes. U.S. Forest Service, Northern Research Station, 2010. http://nrs.fs.fed.us/disturbance/ invasive_species/eab/biology_ecology/planipennis/. “Emerald Ash Borer.” Pennsylvania Department of Conservation and Natural Resources, 2009. http:// www.dcnr.state.pa.us/forestry/fpm_invasives_EAB.aspx. “Emerald Ash Borer.” Wikpedia, 2010. http://en.wikipedia.org/wiki/Emerald_ash_borer. “Emerald Ash Borer Information.” Wisconsin Department of Agriculture, Trade and Consumer Protection, n.d. http://datcp.wi.gov/Environment/Emerald_Ash_Borer/index.aspx. McCullough, Deborah G., Noel F. Schneeberger, and Steven A. Katovich. “Emerald Ash Borer. Pest Alert.” USDA Forest Service, Northeastern Area State and Private Forestry, 2008. http:// www.na.fs.fed.us/spfo/pubs/pest_al/eab/eab.pdf.

n Formosan Subterranean Termite Also known as: FST Scientific name: Coptotermes formosanus Order: Isoptera Family: Rhinotermitidae Native Range. The Formosan subterranean termite is probably native to southern China. It was first described from the island of Taiwan (Formosa) and hence its name. It may have been transported to Japan before 1600. Distribution in the United States. As of 2010, it was established in 10 states: Alabama, California, Florida, Georgia, Hawai’i, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, and Texas. Isolated colonies have been reported in Arizona, Arkansas, New Mexico, and Virginia. Description. Like other termites, the Formosan subterranean termite is a social insect that lives in colonies composed of three castes: workers, soldiers, and the reproductives (alates or swarmers, queen, king, and immature alates). The majority are white to off-white workers that resemble most other termites. Identification of the species relies upon distinguishing soldiers and alates. Soldiers have large teardrop-shaped heads that are orange-brown. Their mandibles are black and sickle-shaped and, when crossed, form an X. Their yellowish-white bodies are about 0.25 in. (6.4 mm) long. Soldiers are aggressive and, when attacked, produce drops of a milky-white, glue-like fluid from a pore (fontanelle) on the front of the head. Soldiers comprise 10–15 percent of the colony. Alates are the winged reproductives; they swarm at night. Since they are attracted to light, they are often found at windows or around light fixtures. They are yellowish brown and have two pairs of wings covered with tiny hairs, visible under the low-power magnification of a hand lens. The wings are clear and of equal length. Two thick veins occur on the leading edge of each wing. Total length is about 0.5 in. (12–15 mm). Since these termites spend much of their lives underground, one is more apt to see signs of their presence rather than the insects themselves. A good indication that Formosan subterranean termites have invaded is the occurrence of shelter tubes made of mud on hard surfaces such as on tree bark, up the side of foundations, and along concrete slabs. Nests made of carton may become exposed on door frames, ceilings, stairs, and near the base of trees. These nests may also be constructed in elevated locations without a connection to the ground. Damage to windows, doors, and floors as well as utility poles, fences, and landscape timbers are other signs that large termite colonies are nearby.

132 n INVERTEBRATES (INSECTS) Related or Similar Species. No other termites in the United States build nests of carton, a mixture of termite excrement, chewed wood, saliva, and soil. The feeding galleries of Formosan subterranean termites are essentially free of soil, whereas native subterranean termites fill their galleries with soil and fecal material. Infested timbers often have layers of moist soil in areas where termites are active. The alates of native subterranean termites (Reticulitermes spp.) are smaller, their wings have no hairs, and they swarm in daylight. Among native subterranean termites, the proportion of soldiers to workers is usually only 1–2 percent, and the soldiers do not emit a white substance from the fontanelle. Native soldiers’ heads are oblong, and the mandibles do not cross. Introduction History. The Formosan subterranean termite may have come to Hawai’i as early as 1869, but it was not officially reported there until 1913. Its first record in the Top: The Formosan subterranean termite is believed to be native to continental United States is offisouthern China. It was first described from the island of Formosa, now cially 1965, when it was discovTaiwan. Bottom: The Formosan subterranean termite was established in ered at a shipyard in Houston, 10 states by 2010 and reported in 4 others. (Adapted from “Just the Texas. It probably arrived in Facts . . . Formosan Subterranean Termite,” 2006.) crated and palleted military supplies on ships returning from the Pacific after World War II. Indeed, the termite seems to have spread around the world on ships; the earliest sites of infestations are at ports. In 1966, it was reported in Louisiana (New Orleans and Lake Charles). The first official report of the termite in South Carolina (Charleston) was made in 1967, but a search of earlier collections revealed its presence by 1957. First reports of the Formosan subterranean termite in Florida date to 1980– 1983; Alabama, 1985–1987; Tennessee (Memphis), 1985; North Carolina, 1990; California (San Diego County), 1991; and Georgia (Atlanta), 1993. The termites are poor flyers and do not spread rapidly on their own. After the initial introductions, the termites were likely accidentally transported in contaminated building and plant materials brought in from previously infested areas. They are commonly associated with used railroad ties, a popular landscape timber. In general they have remained confined to the southeastern

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United States at latitudes south of 32°300 N. However, the availability of centrally heated buildings may allow them to extend their range farther north. Habitat. Natural forests, planted stands of trees, and urban areas. Formosan subterranean termites live underground in moist areas with moderate temperatures. Their nest will be below frost level, but above the water table. They also build aerial nests on structures where they can find moisture. Such sites include boats, porches, flat roofs where water pools, rooftops with vegetation, and gut- Formosan subterranean termite worker (top) and soldier (bottom). ters. They will exploit live and (Gerald J. Lenhard, Louisiana State University, Bugwood.org.) dead trees as nesting sites. Often the nest is outdoors, and a man-made wooden structure is used only as food. The nest is generally accessed from the ground. Mud galleries or shelter tubes connect nests to food sources. Diet. These termites consume cellulose from wood, cardboard, or paper. Bacteria and other microorganisms in the gut digest the cellulose, releasing nutrients and energy for the termite. They usually attack wood in contact with the ground and hollow out galleries by feeding between the growth rings. Although they will chew through metal sheeting, asphalt, some plastics, foam insulation, and plaster, they do not eat these materials. It is often reported that they can hew through concrete, but they actually need preexisting cracks, which they then enlarge. The termites feed over a foraging territory that may be several thousand square feet in area. Life History. Major swarms of Formosan subterranean termites begin in late spring and continue through the summer. They occur on humid, still evenings, usually at dusk. A single colony may release 70,000 or more winged reproductives. They fly only a short distance (60–150 ft. or 20–50 m) and then shed their wings. The female searches for a nesting site in moist crevices near a good supply of wood and the male follows her. Together, they hollow out a royal chamber. The pair, now king and queen, mate, and in a few days, the queen produces 15–30 eggs. The eggs hatch in 2–4 weeks and are cared for by the king and queen until they become third instars. These young termites will care for the next batch of larvae, which will hatch from the second laying of the queen. The queen will continue to lay 2,000 eggs a day. It may take 3–5 years before the colony is large enough to produce alates or to cause noticeable damage to trees and structures. Mature colonies will have as many as 10 million workers, soldiers, a primary queen, and several secondary reproductives. Workers forage and take care of eggs and larvae and feed the larvae, soldiers, and reproductives. Soldiers defend the colony. The secondary reproductives take over egg production if the queen or king dies. Impacts. Termites feed on wood used in construction as well as on living trees. They hollow out the structure they are feeding upon, leaving a papery-thin covering behind. This activity weakens and destroys beams, floors, sills, and the like and kills trees, including

134 n INVERTEBRATES (INSECTS) those of aesthetic and commercial value. While individual Formosan subterranean termites do not eat more wood than native species, the colonies are so much larger that more damage results more quickly. Reportedly, in Hawai’i where a house was built on top of a termite nest, the house was almost completely destroyed in two years. In Hawai’i, it is the single most economically important insect pest in the state. Before Hurricane Katrina, the Formosan subterranean termite cost New Orleans $300 million a year for control, repairs, and replacement of utility poles due to this species. After hurricanes Rita and Katrina, the highest concentrations of this pest in the continental United States were in the flooded cities of New Orleans and Lake Charles, Louisiana. Cleanup of soggy debris and downed trees only spread the termite, which was also attracted to brown rot fungi growing on wet wood and wallboard. The IUCN has nominated this insect to be among “100 of the ‘World’s Worst’ invaders.” Management. Preventive measures include the use of pressure-treated wood wherever timbers come in contact with the ground. It is also important to prevent the build-up of moisture from leaky pipes, lawn irrigation sprinklers, clogged gutters, air conditioning condensate, and rainwater. Chemical barriers can be placed outside a structure both during and after construction. Baits that use a chitin synthesis inhibitor are effective in eliminating an entire colony. General groundskeeping is also a good preventive practice. Remove dead trees and stumps and scrap wood piles from the property and reduce or do away with the use of mulch near a building’s foundation. Once a population has become well established, it may impossible to eradicate it.

Selected References Carlson, Elizabeth. “The Formosan Subterranean Termite.” BugwoodWiki. Center for Invasive Species and Ecosystem Health, University of Georgia, 2008. http://wiki.bugwood.org/The_Formosan _Subterranean_Termite. Hu, Xing Ping. “Formosan Subterranean Termites.” Alabama Cooperative Extension System, Alabama A&M University and Auburn University, 2003. http://www.aces.edu/pubs/docs/A/ANR-1035/. “Just the Facts . . . Formosan Subterranean Termites.” U.S. Army Center for Health Promotion and Preventive Medicine, Entomological Sciences Program, 2006. http://phc.amedd.army.mil/PHC %20Resource%20Library/FormosansubterraneantermitesJan2010.pdf. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Coptotermes formosanus (Insect).” ISSG Global Invasive Species Database, 2006. http:// www.issg.org/database/species/ecology.asp?si=61&fr=1&sts=sss. Su, Non-Yao, and Rudolf H. Scheffrahn. “Featured Creatures: Formosan Subterranean Termite.” Entomology Department, University of Florida, 2000. http://www.entnemdept.ufl.edu/creatures/ urban/termites/formosan_termite.htm.

n Glassy-Winged Sharpshooter Also known as: GWSS Scientific name: Homalodisca vitripennis Synonym: Homalodisca coagulata Order: Hemiptera Family: Cicadomorpha Native Range. Glassy-winged sharpshooters are native to the southeastern United States, where it occurs from eastern Texas to southern North Carolina.

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Distribution in the United States. This leafhopper is a native transplant to California. Description. The glassywinged sharpshooter is a relatively large leafhopper, measuring from 0.4–0.5 in. (1.1– 1.4 cm) long. Females are slightly larger than males. The back is generally brown; small ivory to yellow spots dot the head and thorax. The underside of the abdomen is white; face and legs are yellow-orange. Wings are transparent with red veins. Some females have a large white spot on the middle of each wing composed of a powdery material (brochosomes) that is secreted by the insect. Nymphs look like adults except that they are gray and wingless. Related or Similar Species. The glassy-winged sharpshooter can be told from almost all other sharpshooters by its large size. It is most similar to the native smoke tree sharpshooter (Homalodisca liturata), a close relative. The smoke tree has wavy markings on its body instead of the Top: The glassy-winged sharpshooter is native to the southeastern United spots characteristic of the glassy- States. (Adapted from Conklin and Mizell 2009.) Bottom: Glassy-winged winged sharpshooter. sharpshooters infest several counties in southern California and threaten Introduction History. Glassy- agricultural areas is the Central Valley and northern parts of the state. winged sharpshooters were (Adapted from “Glassy-Winged Sharpshooter in California.” California first collected near Irvine, Department of Food and Agriculture, 2010. http://www.cdfa.ca.gov/ pdcp/Maps/GWSS_Distribution2010.jpg.) California, in 1989, although it was mistakenly identified as the native smoke tree sharpshooter at the time and not recognized as an introduced species until 1994, when it was properly identified in Ventura County. It had probably arrived as egg masses on plants imported from the southeastern United States. It first became abundant in commercial groves of citrus and avocado and on some woody ornamentals such as crape myrtle. Its presence was visible when “leafhopper rain” evaporated and whitened leaves. Toward the middle of the 1990s, the glassy-winged sharpshooter moved inland in Riverside and San Diego counties. By the end of the 1990s, large populations occurred in southern Kern County in citrus groves and vineyards. It is expected that it will become a permanent resident in suitable habitats in the Central Valley and throughout northern California.

136 n INVERTEBRATES (INSECTS) Habitat. In California, it prefers riparian woodlands in coastal and foothill areas. In its native range, it occupies the forest edge. It also feeds and reproduces on woody ornamental trees, vines, and annuals. Crape myrtle and sumac seem to be preferred in its native range; in California, it inhabits eucalypts and coast live oaks, and it is also found on grapevines and citrus, avocado, and macadamia trees. Diet. Adult glassy-winged sharpshooters suck the sap from the xylem—the tissues that distribute water and dissolved nutrients from the roots—of a wide variety of host plants. Feeding times are synchronized with peak nutrient content in the host plant. The insects insert mouthparts that serve as straws into the xylem. Nutrients in xylem fluid are very diluted, so large volumes of fluid must be processed. The result is that glassy-winged sharpshooters produce large amounts of watery wastes (“leafhopper rain”) that Adult glassy-winged sharpshooter. (Russ Ottens, University of Georgia, can coat the canopies of infected Bugwood.org.) trees with a white residue as the excreta evaporates. Adult glassy-winged sharpshooters are able to feed on older wood than other sharpshooters because of their larger mouthparts, and this also allows them to feed on dormant trees and vines during the winter. They tend to feed closer to the base of grapevines and other plants than do other sharpshooters. Young nymphs feed on the stems of the plant on which they hatch. Life History. In California, mating occurs in spring and summer. Two generations are produced each year. Initial egg-laying continues from late February through May. Each female produces 10–12 eggs at a time and deposits them underneath the lower epidermis of leaves of selected host plants. As she lays the eggs, she covers them with white scrapings of brochosomes from her wings. Two weeks later, the eggs hatch into small nymphs that will undergo five molting stages before they are mature. The first generation matures and, from June through September, lays eggs for the second generation of the year. Adults live about two months between generations. The adults from the second generation will produce young the following year. Populations peak in summer and begin to decline in late August. With the approach of winter, adults move into forested areas, where they go into

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semi-hibernation in the leaf litter until warmer temperatures return and they can begin to mate. Impacts. The glassy-winged sharpshooter, throughout its life cycle, is a vector for plant diseases associated with strains of the bacterium Xylella fastidiosa. As such, it is a major threat to California’s billion-dollar grape industry, where it is already implicated in an increase in Pierce’s disease. Pierce’s disease clogs the xylem and destroys a plant’s ability to draw water and nutrients from the soil to its leaves. At first, the tips of leaves turn brown and die, and in 1–2 years, the entire infected vine dies. Pierce’s disease itself is not new to California and has probably been there for at least 100 years. The problem is that the glassy-winged sharpshooter is a more effective transmitter of the bacterium than native sharpshooters because it is more of a generalist in terms of hosts, has greater mobility (up to 0.25 mi. per day), and has larger mouthparts. While other species feed on the parts of the vine that get pruned away, the glassy-winged sharpshooter feeds at the basal stems, and the infection can become systemic or chronic, spread to other vines, and wipe out whole vineyards where table grapes, wine, or raisins are produced. Different strains of the X. fastidiosa bacterium cause diseases in other valuable plant species, and the glassy-winged sharpshooter could become a vector for almond leaf scorch, phony peach disease, alfalfa dwarf, and citrus variegated chlorisis, which affects orange trees. It is already involved in the spread of oleander leaf scorch. Oleanders are widely planted as ornamental shrubs in southern California, particularly in freeway medians, but also in parks and suburban yards. The cost to the California Department of Transportation should it have to remove diseased oleanders and replant medians with other ornamentals would be well over $50 million. The wholesale nursery trade is also economically affected, as ornamental plants require inspection and treatment with insecticides before transport to other parts of California or neighboring states. Management. Management is aimed at containing the invasion and preventing outbreaks of Pierce’s disease and related plant diseases in new areas. Better early detection methods are needed. Short-term strategies to slow the spread of the disease include the use of systemic insecticides and behavior modifiers that would disrupt the transmission of the bacteria. Biological control of the glassy-winged sharpshooter may be possible by using a small wasp from Texas and northern Mexico, Gonatocerus truguttatus, that is an egg parasite of the glassy-winged sharpshooter; or by inserting genes conferring resistance to X. fastidiosa into host plants or rootstocks. Other bacteria or fungi may be found that are restricted to xylem tissues and interfere with X. fastidiosa’s reproduction or transmission. One candidate is the fungus Hirsutella sp. that affects glassy-winged sharpshooters in their native range.

Selected References Cimino, Andria. “Glassy-Winged Sharpshooter, Xylophagous Leafhopper (Homalodisca coagulata).” Introduced Species Summary Project, Columbia University, 2002. http://www.columbia.edu/itc/ cerc/danoff-burg/invasion_bio/inv_spp_summ/Homalodisca_coagulata.html. Conklin, Tracy, and Russell F. Mizell III. “Featured Creatures: Glassy-Winged Sharpshooter.” University of Florida, Institute of Food and Agricultural Sciences, 2009. http://entomology .ifas.ufl.edu/creatures/fruit/glassywinged_sharpshooter.htm. Garrison, Rosser W. “New Agricultural Pest for Southern California: Glassy-Winged Sharpshooter (Homalodisca coagulata).” County of Los Angeles, Agricultural Commissioner/Weights and Measures Department, 2001. http://acwm.co.la.ca.us/pdf/GWSSeng_pdf.pdf.

138 n INVERTEBRATES (INSECTS) Hoddle, Mark S. “The Glassy-Winged Sharpshooter.” Center for Invasive Species Research, University of California, Riverside, 2003. http://cisr.ucr.edu/glassy_winged_sharpshooter.html. National Biological Information Infrastructure and IUCN/SSC Invasive Species Specialist Group. “Homalodisca vitripennis (Insect).” ISSG Database, 2006. http://www.issg.org/database/species/ ecology.asp?si=240&fr=1&sts. Pierce’s Disease Research and Emergency Response Task Force. “Glassy-Winged Sharpshooter (Homalodisca coagulata).” University of California, Agriculture and Natural Resources, n.d. http:// news.ucanr.org/speeches/glassywinged.html.

n Gypsy Moth Also known as: European gypsy moth Scientific name: Lymantria dispar Order: Lepidoptera Family: Lymantridae Native Range. The gypsy moth comes from the temperate broadleaf forests of Eurasia and northern Africa. European and Asian subspecies have evolved. The gypsy moth that is now invasive across the eastern United States originated in Europe. The first egg masses were brought from France. Distribution in the United States. Gypsy moths are established in many northeastern states and continue to expand their distribution area westward and southward. Currently they occur from northern North Carolina to Maine and west through Ohio and northern Indiana into Wisconsin. Description. Gypsy moths are sexually dimorphic. The female is white with dark chevrons across the forewings. She has a wing span of about 2 in. (80 mm) but is flightless. Her body is covered with hairs, and her antennae are slender. The male is darker and smaller. His wings are dark brown with black banding, and he has feathery antennae. A strong flier, the male has a wingspan of about 1.5 in. (60 mm). The abdomen of the male is narrower than that of the female. Eggs are deposited in oval masses that are covered with soft, buff-colored hairs from the female’s abdomen. The velvety masses are about 1.5 in. (60 mm) long and 0.75 in. (30 mm) wide. Newly hatched larvae are about 0.125 in. (3 mm) long and initially tan, but become black within four hours. Younger caterpillars (first to fourth instars) are brown to black and have long body hairs. Late instars are black with 11 pairs of bumps (tubercles) along the back. The forward five pairs are blue; the rear six pairs are red. Each tubercle has a tuft of yellow or brown hairs. A single yellow line runs the length of the back of younger caterpillars from the head to the last segment. Additional yellow lines adorn the head of fourth through sixth instars. True legs are dark red. At maximum growth, the caterpillars are 2–3 in. (80–120 mm) long. Pupae are dark red-brown and teardrop-shaped, rounded in the front, and tapered toward the rear. Each pupa attaches to a substrate by means of a few strands of silk. Male pupae are 0.75–1.5 in. (30–60 mm) long; female pupae are up to 2.5 in. (100 mm) long. Related or Similar Species. The Asian gypsy moth is a subspecies of Lymantria dispar that is occasionally intercepted at western ports. The adult moths look very similar to the European variant that has invaded the northeastern United States, but the female is a strong flier. Asian caterpillars vary more in color than European ones. It is safe to assume, for now, that any flying white moth is not a gypsy moth.

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Gypsy moth caterpillars might be mistaken for some native tent caterpillars; however, gypsy moths never make tents or webs. The eastern tent caterpillar (Malacosoma americanum) has a white line down its back and light blue and black spots on the sides. The forest tent caterpillar (Malacosoma disstria) has a line of white blotches the length of its back, and light blue stripes on the sides. The fall web worm (Hyphantria cunea) is greenish or yellow with long white hairs and has a black stripe down the back and a yellow stripe on each side. Introduction History. The introduction of the gypsy moth can be traced to a single person and a specific address. A Frenchman and amateur entomologist, Etienne Leopold Trouvelet, had come to Medford, Massachusetts, with his family in 1852. He was interested in identifying American silkworms for possible use in producing silk. For unknown reasons, in 1868 or 1869, after a visit to France, he brought some gypsy Top: The gypsy moth’s native range coincides with the temperate moth egg masses back to his broadleaf forests of Eurasia and North Africa. (Adapted from “Gypsy house at 27 Myrtle Street. It Moth around the World.” USDA Forest Service. http://www.fs.fed.us/ne/ seems he let the eggs develop morgantown/4557/gmoth/world/.) Bottom: The gypsy moth continues on trees in the backyard. When to spread southward and westward from established populations in the Northeast and Great Lakes region. (Adapted from “Gypsy Moth some caterpillars escaped, he Quarantine Map.” USDA Forest Service, 2007. http://www.fs.fed.us/ne/ notified local authorities, but morgantown/4557/gmoth/atlas/q2007.gif.) no effort was made to eradicate them. In 1882, a gypsy moth outbreak on Myrtle Street marked the first evidence of an emerging problem. The gypsy moth population continued to grow, and in 1889, the first program to eradicate the moth began. The Massachusetts State Board of Agriculture implemented manual removal of egg masses from trees and structures, applied pesticides, and burned infested forests, all to no avail. Eradication efforts ceased in 1900. The historical rate of spread between 1900 and 1915 is estimated to have averaged about 6 mi./year (9.5 km/year). By 1934, gypsy moths had spread north through Vermont, New Hampshire, and Maine and south into Connecticut and Rhode Island. Expansion rates had slowed to less than 2 mi./year

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A. Gypsy moth caterpillar. (John H. Ghent, USDA Forest Service, Bugwood.org). B. Adult moths, male (left) and female (right). (USDA Forest Service Archive, USDA Forest Service, Bugwood.org.)

(2.8 km/year) between 1916 and 1965, so that by 1965, only eastern New York State, including Long Island, was added to the distribution area. After 1965, the rate of spread again increased, as did the range of the gypsy moth. At an estimated spread rate of nearly 13 mi./year (21 km/ year), the gypsy moth moved south through Pennsylvania and New Jersey into Maryland, West Virginia, and Virginia and west across northern Ohio, into Michigan, and eventually Wisconsin and northeastern Minnesota. Nothing suggests that this spread has stopped. Newly hatched (first instar) gypsy moth caterpillars sometimes move down from the tree canopy on silken threads that break in strong winds, carrying the larvae out of the canopy. Updrafts can carry them as much as 12 mi. (nearly 20 km) from the tree where they hatched. However, most dispersal to new areas is probably achieved by unintentional human transport. Gypsy moth egg cases and larvae can hitchhike on firewood, nursery stock, vehicles, and outdoor equipment. The typical pattern of spread is one of isolated populations appearing ahead of the expanding boundary of the distribution area and then coalescing to form a continuous, new area of infestation. Habitat. Temperate broadleaf deciduous forests are preferred habitat. Populations become densest and resulting defoliation most intense on dry ridges and other areas with shallow soils or excessively drained soils. Coniferous forests, urban and suburban landscapes, and agricultural environments also have habitat value for gypsy moths. Diet. Gypsy moth caterpillars feed on foliage. Adult moths do not have mouthparts and thus do not eat at all. Host plants are extremely varied; over 500 different types can be consumed. Suitability of plant species for forage depends on the developmental stage of larvae. In general, trees under stress are more vulnerable to attack than healthy specimens. In the northeastern United States, oaks are the most favored hosts, but maples, hickories, and many other hardwoods are also eaten. Trees that are avoided include American holly, ash (Fraxinus spp.), black walnut (Juglans nigra), butternut (Juglans cinerea), flowering dogwood (Cornus florida), mountain laurel (Kalmia latifolia), balsam fir (Abies balsamea), and arborvitae (Thuja occidentalis). Life History. Moths emerge from pupae in summer, males usually 1–2 days ahead of females. A few hours after emergence, females release a pheromone that attracts males,

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which fly as much as 0.5 mi. (0.8 km) upwind to mate with them. Females deposit eggs within 24 hours of mating. Egg masses are placed on tree trunks and the undersides of branches as well as in crevices in the bark and under loose bark. They also may be laid on camping gear and in vehicles or anywhere else to which females can crawl. The eggs are covered with hairs from the female’s abdomen that probably provide some protection from predators and cold temperatures. Although development from embryo to larva is completed within a month, larvae enter diapause and overwinter inside the egg. Eggs hatch the following spring at about the time leaf buds open on oak trees. Most larvae in a given egg mass hatch within seven days of each other. In cool or rainy weather, they stay near the remains of the egg mass, but once the sun shines, they move upward toward the light into the canopy of the tree. Larvae feed first on new leaves and, when not feeding, stay attached by silk threads on the undersides of leaves. The caterpillars undergo molts about once a week to accommodate their growth. Males have four molts; females five. The larval period lasts about 40 days, after which time each caterpillar finds a pupation site, wraps itself in a thin silk net, and rests for 1–2 days before becoming a pupa. The pupa erupts from the larval skin and becomes dark reddish-brown; it stays in the silk net for the next two weeks while development into an adult moth is completed. When the adult moth emerges, it takes a few hours to expand its wings. The males then fly away in search of females. Adult moths live about a week. Gypsy moth populations are cyclical. A low-level, innocuous phase may last several years, to be followed by a release phase of 1–2 years’ duration that sees an increase in population density of several orders of magnitude. The next phase is the outbreak phase, when population density is great enough that defoliation is evident over a considerable area of forest. Outbreaks rarely last more than one or two years before starvation and disease cause the population to crash in what is known as the decline phase. The foliage of infested trees may respond by increasing levels of toxic chemicals and decreasing the nutritive value of leaves, contributing to the die-off. Naturally occurring pathogens such as the fungus Em (Entomophaga maimaiga)—originally introduced from Asia when Massachusetts was attempting to stamp out gypsy moths in the early 1900s—and NPV (nucleopolyhedrosis virus) commonly contribute to population declines. Population cycles are synchronous over large distances, but they proceed aperiodically. Impacts. Gypsy moths, especially during outbreaks, defoliate hardwood and sometimes softwood trees. This can weaken the tree, making it more susceptible to drought, diseases, and other pests such as the shoestring fungus (Armillaria mellea) and the two-lined chestnut borer (Agrilus bilineatus). Defoliated forests open the forest floor to sunlight, causing accelerated drying of leaf litter and increased forest-fire risk. Most trees can recover from a single defoliation event, but several defoliations in successive years can kill them. In the Northeast, an estimated 20 percent of forest trees die after heavy infestations. How this will affect species composition and ecological dominance is as yet unknown, but in time, ecologically dominant oaks could be replaced by less palatable tree species, which would have ripple effects throughout the forest community. The loss of trees and the unsightly mess of hundreds of caterpillars and a constant rain of their feces from the treetops during an outbreak can negatively affect not only timber production, but also tourism and recreation. Other economic costs are incurred in inspection and other control measures. Automobile and train wrecks on roads and tracks slippery with caterpillars have been reported during some severe outbreaks. Management. Gypsy moth control is aimed at suppressing existing populations, eradicating pioneer populations, and slowing the spread of this invasive moth. Homeowners can control small local infestations by manually scraping and destroying egg masses from trees

142 n INVERTEBRATES (INSECTS) in their yards or attaching sticky barrier bands to tree trunks to prevent the migration of caterpillars. More widespread suppression of populations is achieved by spraying areas with Bt (Bacillus thuringiensis), a bacterium that produces a chemical toxic to moth and butterfly larvae. The National Gypsy Moth Slow the Spread (STS) program, a joint local, state, and federal initiative, was implemented in 1999 to monitor recently established and still-isolated lowlevel populations in zones between infested areas and non-infested areas. Along the front line of range expansion, gypsy moth population monitoring is conducted with pheromone traps to capture males, and several types of barriers are placed on tree trunks to collect larvae. Direct counts of egg masses are also employed. Once new infestations are identified, Integrated Pest Management (IPM) and other controls are initiated to eradicate or suppress the population. APHIS has established quarantine areas in much of the infested region. Nursery stock, firewood, vehicles, outdoor equipment, and household items moving out of these areas into non-infested ones must be inspected by certified inspectors.

Selected References Baczynski, Tracy. “European Gypsy Moth (Lymantria dispar).” Introduced Species Summary Project, Columbia University, 2002. http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/ inv_spp_summ/Lymantria_dispar.htm. “Gypsy Moth.” Animal and Plant Health Inspection Service, U.S. Department of Agriculture, 2010. http://www.aphis.usda.gov/plant_health/plant_pest_info/gypsy_moth/index.shtml. “Gypsy Moth Pest Profile.” California Department of Food and Agriculture, State of California, 2010. http://www.cdfa.ca.gov/phpps/pdep/target_pest_disease_profiles/gypsy_moth_profile.html. “Integrated Pest Management Manual: Gypsy Moth.” National Park Service, U.S. Department of the Interior, 2010. http://www.nature.nps.gov/biology/ipm/manual/gypsymth.cfm. Liebold, Sandy. “Gypsy Moth in North America.” Forestry Sciences Laboratory, Forest Service, Northeastern Research Station, U.S. Department of Agriculture, 2003. http://www.fs.fed.us/ne/ morgantown/4557/gmoth/.

n Hemlock Woolly Adelgid Also known as: Woolly Scientific name: Adelges tsugae Order: Homoptera Family: Adelgidae Native Range. Hemlock woolly adelgids are native to Asia. They are known to be from Japan, Taiwan, southwestern China, and India. Genetic analysis has determined that those in the eastern United States came from southern Japan. In their native range, these adelgids utilize both hemlocks and spruces and undergo both asexual and sexual reproduction. Asian hemlocks appear to have developed resistance to adelgid attacks. Distribution in the United States. The hemlock woolly adelgid is invasive in 16 eastern states from southeastern Maine to northern Georgia and west to eastern Kentucky, Tennessee, and West Virginia. Its distribution area continues to expand; and it may soon become established in Ohio, where isolated collections have occurred. In the western United States, where it is not a pest, it occurs from northern California to southeastern Alaska. Description. The hemlock woolly adelgid is a tiny, aphid-like insect less than 1/16 in. (1.5 mm) long. They are oval and blackish gray in color. Newly hatched nymphs (first

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instars) are about the same size, but reddish brown. The insect probably would not be noticed were it not for the fact that nymphs covers themselves in white wax-like filaments and adults secrete a white “woolly” ovisac in which to lay their eggs. The woolly or cottony casings are about 1/8 in. (3 mm) in diameter and quite visible at the base of needles on the undersides of the outermost tips of hemlock branches from late fall to early summer. Introduction History. The hemlock woolly adelgid was first identified on the West Coast in 1924. First reports on the East Coast came from Richmond, Virginia, in 1951. It may have been accidentally imported on nursery stock from Japan. Today, it continues to spread on ornamental hemlocks via the nursery trade, but earlystage larvae and eggs can be transported by birds and mammals moving through hemlock forests. The wind can disperse infested twigs as well as the mobile crawlers. Also, humans Top: The hemlock woolly adelgid is native to coniferous forests from can unintentionally transport India to Japan. (Adapted from Reardon, R., et al. “Biological Control of eggs, nymphs, and adults on Hemlock Woolly Adelgid.” U.S. Department of Agriculture, Forest live ornamental trees and with Service. Forest Health Technology Enterprise Team. Burlington, VT. debris from dead and dying FHTET-2004-04. http://wiki.bugwood.org/Archive:HWA/Introduction.) Bottom: The hemlock woolly adelgid is currently invasive in 16 eastern hemlocks. The hemlock woolly states, and it continues to expand its range. In the west it is not adelgid appeared in Shenan- considered a pest. (Adapted from “Counties with Established HWA doah National Park in Virginia Populations 2009.” USDA Forest Service. Http://na/fs/fed/us/fnp/hwa/ in the 1980s, moved southward maps/2009.pdf.) on the Blue Ridge Parkway in the 1990s, and was in Great Smoky Mountains National Park by 2002. In 2007, it was spreading at a rate of nearly 10 mi./year (15.6 km/year) in the southern part of its range and 5.0 mi./year (8.13 km/year) in the northern part. By some estimates, it could kill all the hemlocks in the southern Appalachians by 2020. Habitat. In the United States, these aphid relatives are restricted to hemlocks, although in their native range, certain spruces are hosts during the sexually reproducing stages of the life cycle. In the eastern United States, this adelgid infests both eastern hemlock (Tsuga

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A. Woolly casings on a hemlock twig infested with hemlock woolly adelgids. (Connecticut Agricultural Experiment Station Archive, Connecticut Agricultural Experiment Station, Bugwood.org). B. The aphid-like adult adelgid. (Michael Montgomery, USDA Forest Service, Bugwood.org.)

canadensis) and Carolina hemlock (T. caroliniana). In the West, the woolly hemlock adelgid occurs on both western hemlock (T. heterophylla) and mountain hemlock (T. mertensia), but these trees are resistant, and the adelgid is not considered a pest. Diet. Nymphs and adults suck sap from the twigs of hemlocks. They feed at the base of new needles by extracting starch-rich fluids from the tissues in the xylem that manufacture and store the plant’s food. At the same time, they inject toxins in their saliva into the plant. Life History. Hemlock woolly adelgids have both sexual and asexual (parthenogenic) stages in the life cycle, but U.S. populations only multiply asexually; all are females. Six stages of development define the life cycle: egg, four instars of nymphs, and adult. Two generations are produced each year. In March, females that had overwintered lay 20–75 eggs and cover them in cottony material excreted by the adult. Larvae, known as crawlers, emerge in April and May and move to feeding places at the bases of hemlock needles. They may hitchhike to nearby hemlocks on birds and mammals or be blown there by the wind. When the crawlers settle, they become immobile nymphs. By June, they have matured into wingless and winged adults. The winged females fly off looking for spruce trees, but since no suitable host spruces exist in the United States, most of them presumably die without reproducing. If there were such spruces, these females would reproduce sexually. The wingless females reproduce asexually and lay 100–300 eggs that will become the second generation of the year. The larvae hatch in early July, settle at the bases of hemlock needles, and then go into dormancy through the hot summer months. Nymphs resume development in October and November and feed throughout the winter, maturing into adult females early the next spring. Impacts. Hemlock woolly adelgids weaken and kill eastern and Carolina hemlocks, including those in forests and those cultivars used as ornamental trees and hedges. To date, the most severe impacts have occurred in parts of Virginia, New Jersey, Pennsylvania, and Connecticut. In the Northeast, hemlock decline and death takes 4–10 years; in the southern Appalachians, the pace is more rapid, and trees may die in only 3–6 years. Infestations often start in large, mature hemlocks, which may be 150 ft. (45 m) tall and more than 500 years old. Infested trees can be identified first by their grayish-green needles that contrast with

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the glossy green of healthy hemlocks. Defoliation follows, progressing from the lower branches upward and ultimately causing the death of the tree. The rate and extent of hemlock decline are accelerated by other stress factors, such as drought, poor soil conditions, and other pests and diseases. Hemlocks form important habitat for numerous birds from warblers to turkeys, and for small mammals such as snowshoe hares and rabbits; they produce a deep shade along mountain streams that maintains the cool water temperatures needed by trout and other fish. The loss of the hemlock canopy increases light penetration to the forest floor, drying and warming riparian and riverine habitats in the summer and reducing shelter in upland habitats in winter. Research suggests that nitrogen cycles are altered when hemlock stands perish. The demise of hemlocks could have cascading effects that would alter forest ecosystems in much of the eastern United States. Management. Few environmentally sound methods for controlling hemlock woolly adelgids in forests are available. Natural predators and pathogens exist, but fail to lower population levels enough to prevent tree deaths. Biological control by Asian beetles, such as the ladybird beetle (Pseudoscymnus tsugae), that limit their attacks to adelgids and control them in Japan, hold some promise; several states have released them experimentally. DNA research suggests that Asian hemlocks have evolved a degree of resistance to adelgid infestations. Crossing eastern hemlocks with Asian hemlocks has successfully maintained the appearance of the eastern hemlock but produced a tree that discourages adelgid settlement and slows the growth of those nymphs that do feed upon it. Isolated trees in yards or parks can be treated with insecticidal soaps, or adelgids can be physically removed with strong sprays of water; but these treatments must be repeated often. Removal of infected branches will slow the decline of the tree. In Great Smoky Mountains National Park, treatments with systemic insecticides that are applied at the roots or injected into the trunk of trees in campgrounds have reversed some of the impacts of the infestation and remained effective for several years. Preventing or slowing the spread of the adelgid can be aided by cultural control methods such as not moving live plants, logs, firewood, or bark chips from infested areas. Selective removal of heavily infested trees reduces that likelihood that wind, birds, and other wildlife will disperse eggs and nymphs. When replanting landscape trees, the use of adelgid-resistant hemlock species, such as T. diversifolia and T. sieboldii from Japan or western and mountain hemlocks from the Pacific Northwest, instead of eastern hemlock will limit the availability of suitable host trees and may help control adelgid populations.

Selected References Chowdhury, Shahrina. “Hemlock Woolly Adelgid (Adelges tsugae).” Introduced Species Summary Project, Columbia University, 2002. http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/ inv_spp_summ/Adelges_tsugae.html. “Hemlock Woolly Adelgid.” Pest Alert, State and Private Forestry NA-PR-09-05. U.S. Department of Agriculture, Forest Service, Northeastern Area, 2005. http://na.fs.fed.us/spfo/pubs/pest_al/ hemlock/hwa05.htm. McClure, Mark S. “Hemlock Woolly Adelgid, Adelges tsugae (Annand).” Connecticut Agricultural Experiment Station, 1998. http://www.ct.gov/caes/cwp/view.asp?a=2815&q=376706. Pennsylvania Department of Conservation and Natural Resources. “Hemlock Woolly Adelgid.” Commonwealth of Pennsylvania, 2009. http://www.dcnr.state.pa.us/forestry/woollyadelgid/ index.aspx.

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n Japanese Beetle Scientific name: Popillia japonica Order: Coleoptera Family: Scarabaeidae Native Range. Japan. Distribution in the United States. The Japanese beetle is established in all states east of the Mississippi River except Florida. Noncontinuous infestations occur west of the Mississippi in Arkansas, Colorado, Iowa, Kansas, Minnesota, Missouri, Nebraska, and Oklahoma. Far-western states are protected by quarantine, and any beetles arriving have, so far, been eradicated. Description. The Japanese beetle is an oval-shaped, metallic-green insect about 0.5 in. (10–13 mm) long and 0.25 in. (6–7 mm) wide. The wing covers are bronze-colored and extend almost the full length of the abdomen. Five small white tufts of hair line each side of the body and two others lie just posterior to the wing covers. Males are usually slightly smaller than females. Japanese beetles travel and feed in groups. Eggs are spherical and almost translucent. They swell to a diameter of about 0.08 in. (2 mm) before hatching. The grub or larvae is white with a reddish-brown head. It has three pairs of legs and lies curled in the form of a C. Fullgrown larvae are about 1.0 in. (26 mm) long. The pupa looks like a cream-colored or tan adult with the legs folded close to the body. Related or Similar Species. Japanese beetle larvae look like those of most beetles and can be distinguished by a V-shaped row of spines beneath the abdomen. Top: The Japanese beetle is native to Japan. Bottom: In the United States, Introduction History. The the Japanese beetle occurs in all states east of the Mississippi River except Florida. Isolated populations occur as far west as Colorado. (Adapted Japanese beetle was first discovered in a nursery in Riverton, from APHIS, 2004.)

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A. Adult Japanese beetle. (David Cappaert, Michigan State University, Bugwood.org.) B. Japanese beetle larvae (grubs) are commonly found in the soil beneath lawns. (David Cappaert, Michigan State University, Bugwood.org.)

New Jersey, in 1916. It is believed that grubs contaminated shipments of iris bulbs sometime before 1912, when inspections of imports began in the United States. In the next 60 years, it spread throughout 22 states east of the Mississippi River. The climate is favorable to the insect, large expanses of turf in lawns and golf courses provide excellent habitat for reproduction, and abundant foliage is available to support adults. The beetle can be spread during any stage of its life cycle in plant materials, soil, and sod. It has now moved into states west of the Mississippi, but for the most part, populations have remained isolated. Hitchhikers on aircraft are continually intercepted at airports in western states, where it could become a major pest in orchards and truck farms. Habitat. Open woods, meadows, farms, gardens, and lawns. Diet. Adult Japanese beetles eat the leaves, flowers, and fruits of hundreds of different plants. Their hosts include trees, shrubs, vines, and perennial and annual herbs, including crops and ornamentals. Preference is for young leaves, which they skeletonize by consuming the green tissue between the veins. Grubs feed primarily on the roots of grasses, but will also consume the roots of annual fruit and vegetable plants. Life History. Adults begin to emerge from pupae in early summer and congregate on plants to feed and mate. Each female leaves the plant upon which she is feeding again and again to deposit 1–4 eggs at a time. In the course of the summer, she will lay 40–60 eggs total. She deposits her eggs in soil at depths of 3–4 in. (1.2–1.6 cm), and preferably beneath turf. The larvae hatch out about two weeks later and begin to feed on plant roots and grow. With the approach of cold weather, the grubs move deeper into the soil to overwinter. When soil temperatures warm in the spring, the grubs migrate back up toward the surface and resume feeding. They pupate and, in 8–20 days emerge as the next generation of adults. The life cycle usually takes a year. Ten months of the cycle are spent in the larval stage. Impacts. Leaves of heavily infested ornamental, truck, and garden plants will turn brown and die. Soft fruits such as grapes and berries may be eaten completely. Grapes injured by beetles become vulnerable to attack by native green June beetles (Cotinus mitida), which are unable to bite into intact grapes themselves. Corn is damaged when Japanese beetles

148 n INVERTEBRATES (INSECTS) eat the silk and prevent the formation of kernels. The larvae damage turf, turning patches of lawns brown when numbers are high. Management. Biological controls can be effective in controlling grubs and hence adult beetles. Applications of milky spore (the bacterium Bacillus popillae) to turf can reduce populations for decades if properly used. Nematodes (Heterorhabditis spp.) also work well in destroying grubs. Commercially available traps lure Japanese beetles away from plants, but may also attract beetles into a yard. Landscape plantings of non-palatable plants such as forsythia, holly, juniper, arborvitae, boxwood, spruce, and yew may deter beetles from massing in suburban properties.

Selected References APHIS. “Managing the Japanese Beetle: A Homeowner’s Handbook.” Animal and Plant Health Inspection Service (APHIS), U.S. Department of Agriculture, 2004. http://www.aphis.usda.gov/ lpa/pubs/pub_phjbeetle04.pdf. Bilberry, S. “Popillia japonica.” Animal Diversity Web, 2001. http://animaldiversity.ummz.umich.edu/ site/accounts/information/Popillia_japonica.html. Day, Eric, Pete Schultz, Doug Pfeiffer, and Rod Youngman. “Japanese Beetle.” Virginia Cooperative Extension, Virginia Tech, and Virginia State University, 2009. http://pubs.ext.vt.edu/2902/2902 -1101/2902-1101.html. “Japanese Beetle Pest Profile.” California Department of Food and Agriculture, 2009. http:// www.cdfa.ca.gov/phpps/pdep/target_pest_disease_profiles/japanese_beetle_profile.html. “Japanese Beetles.” Forest Insect and Disease Newsletter. Minnesota Department of Natural Resources, 2002. http://www.dnr.state.mn.us/fid/november02/japanese.html.

n Multicolored Asian Lady Beetle Also known as: Japanese ladybug, Asian lady beetle, Halloween lady beetle Scientific name: Harmonia axyridis Order: Coleoptera Family: Coccinellidae Native Range. Asia. The native range stretches from the Altai Mountains east to the Pacific Ocean and Japan and from southern Siberia south to southern China. The distribution area includes Kazakhstan, Uzbekistan, Russia, Mongolia, China, Korea, Taiwan, and Japan. This lady beetle has at various times been imported to the United States from Japan, Korea, and Russia. Distribution in the United States. Well-established populations exist in many parts of the Midwest, Northeast, South, and Northwest. Description. Like most other lady beetles, the adult multicolored Asian lady beetle has a domed, oval shape. Populations in the United States contain individuals in a mix of colors, from tan or pale yellow-orange to bright red-orange. They may or may not have black spots on the wing covers. Those that do have up to 10 spots on each wing cover. The middle body segment (pronotum) is white to straw-yellow and usually marked with a distinct black M. Adults are relatively large, measuring about 0.3 in. (7–8 mm) long. Larvae are elongate and flattened; their bodies are covered with flexible spines. Late (fourth) instars are bluish black with a yellow-orange patch on each side of the abdomen. Eggs are bright yellow.

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Related or Similar Species. Many native lady beetles occur in the United States. The most common is the convergent lady beetle (Hippodamia convergens). Adults are somewhat elongate in shape compared to the multicolored Asian lady beetle. Convergent lady beetles have black spots on red wing covers. Behind the head, white lines converge on a black background. They range in size from 0.16 to 0.28 in. (4–7 mm). Native lady beetles do not overwinter indoors. Another introduced lady beetle, the seven-spotted lady beetle (Coccinella septempunctata), from Europe, is established in some northeastern and north central states. It is about the same size as the multicolored Asian lady beetle but has a white spot on either side of its black head. The wing covers are red or orange with 1– 5 spots on each one. It overwinters in sheltered areas outdoors near the fields in which they feed. Introduction History. Multi- Top: The multicolored lady beetle occurs across a broad swath of Asia colored Asian lady beetles have from Kazakhstan to Japan. Bottom: This alien lady beetle is invasive in been deliberately introduced to most of the lower 48 states. (Adapted from “Multicoloured Asian Lady the United States numerous Beetle.” Project UFO. http://www.projectufo.ca/drupal/multicoloured times as agents for the bio- _asian_lady_beetle.) logical control of aphids and aphid-like insects. They were first released by the U.S. Department of Agriculture in California in 1916 and again in the mid-1960s to control pecan aphids. From 1978 to 1982, additional releases were made in Connecticut, Delaware, Georgia, Louisiana, Maine, Maryland, Mississippi, Ohio, Pennsylvania, and Washington. Interestingly, none of these efforts seem to have given rise to established populations. In 1988, a population was discovered north of New Orleans in Louisiana. This may have derived from an accidental introduction. From this point of origin, multicolored lady beetles spread quickly through southern and midwestern states. By 1994, they were reported in Alabama, Florida, Georgia, North Carolina, South Carolina, Ohio, and Minnesota. They were also established in the Northeast by that time, perhaps as a result of other, independent

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A. Adult multicolored Asian lady beetle. (Gerald J. Lenhard, Louisiana State University, Bugwood.org.) B. Larva. (Gerald J. Lenhard, Louisiana State University, Bugwood.org.) C. Pupa. (John Ruberson, University of Georgia, Bugwood.org)

introductions rather than dispersal from the South or Midwest. It is known, for example, that they arrived at ports in South Carolina and Delaware as accidental hitchhikers on imported nursery stock. Habitat. Multicolored Asian lady beetles live in cultivated fields, orchards, vineyards, nurseries, and gardens. They usually overwinter in buildings. Diet. Aphids and similar soft-bodied insects such as scales and psyllids comprise the main food of both adult and larval multicolored Asian lady beetles. An adult can devour 90–270 aphids a day, and a single larva may consume 600–1,200 while it develops. These lady beetles also feed on the larvae of butterflies and of other beetles as well as on injured fruits such as grapes. Life History. Mating takes place in early spring after adults emerge from overwintering sites. Females lay clumps of roughly 20 eggs on the undersides of leaves. The eggs hatch in 3–5 days, and the fast-moving larvae forage on the host plant for aphids and scale insects. The larvae will molt four times as they grow larger. After the fourth molt, they enter an

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immobile pupa stage. The adult beetle emerges from the pupa 5 or 6 days later. The complete life cycle from egg to adult takes 15–25 days. Before the first killing frost of autumn, as prey become less abundant, adults seek shelter indoors. They seem to be attracted by bright reflective surfaces such as the south-facing sides of light-colored buildings. They enter homes and other buildings in huge numbers though cracks and other poorly sealed openings and occupy cool places inside walls, floors, and attics. There they become dormant. Winter aggregations may number in the tens of thousands. On warm, sunny days, they wake up and move to the interior of the building, where they seek the light at windows. With the warming temperatures of springtime, they exit their winter shelters and begin to mate. They do no physical damage to structures and do not reproduce indoors. They may return to the same overwintering sites every year. Adults can live 2–3 years. Impacts. The introduction of the multicolored Asian lady beetle as a biological control agent on shrubs, trees, and a variety of crops has been largely successful. Its consumption of large numbers of aphids, scales, and thrips has reduced the need for chemical pesticides. In California, it has nearly eradicated pecan aphids, and elsewhere significantly reduced soybean aphids after their recent introduction from China. Multicolored Asian lady beetles are a minor, but perhaps increasing, agricultural pest. They appear to displace native lady beetles and other beneficial insects through competition for food and predation. This lady beetle may also depress numbers of the exotic sevenspotted lady beetle (Coccinella septempunctata). In autumn, the beetles congregate and feed on ripening fruits such as pears, apples, and grapes—especially if the fruits have already been damaged by birds or other insects. This is particularly troublesome in vineyards, where it is difficult to remove them from the grapes being harvested for winemaking. Lady beetles get crushed along with the grapes and taint the flavor of the wine. The multicolored Asian lady beetle may be a threat to eggs and caterpillars of the monarch butterfly (Danaus plexippus). Its real infamy, however, derives from its status as an annoying overwintering invader of homes. Numbers can be so great that homeowners can hear them moving in the walls. If a lady beetle is frightened or crushed, it exudes an unpleasant odor and secretes, via reflex bleeding, a yellowish liquid from its leg joints that will stain drapes, carpets, and other light-colored surfaces. They are more a nuisance than a threat, however. They do not destroy wood or textiles or otherwise damage human property. They do not carry diseases. They do not sting, although they can bite. Sensitive people may have allergic reactions to their presence. Management. Preventing multicolored Asian beetles from entering homes is the best way to deal with them. All possible entries should sealed; door and window screens, as well as those in all vents, should be kept in a state of repair; and door sweeps should be installed on exterior doors. Once inside, it is difficult to remove them. The most recommended method is by vacuuming them and employing a means to discard the catch before survivors escape, and before the smell of dead beetles becomes too strong. Swatting them or sweeping them up can lead to reflex bleeding and bad odors. Do not use bug bombs. They may have little effect and will only attract other scavenger insects.

Selected References “Biological Control: A Guide to Natural Enemies in North America: Harmonia axyridis.” Cornell University, College of Agriculture and Life Sciences, Department of Entomology, n.d. http:// www.nysaes.cornell.edu/ent/biocontrol/predators/Harmonia.html.

152 n INVERTEBRATES (INSECTS) Hahn, Jeffrey. “Multicolored Asian Lady Beetles.” University of Minnesota Extension Service, 2004. http://www.extension.umn.edu/distribution/housingandclothing/m1176.html. Jones, Susan C., and Joe Boggs. “Multicolored Asian Lady Beetle.” Ohio State University Extension Fact Sheet, HSE-1030-01.Ohio State University, n.d. http://ohioline.osu.edu/hse-fact/1030.html. Koch, R. L. “The Multicolored Asian Lady Beetle, Harmonia axyridis: A Review of Its Biology, Uses in Biological Control, and Non-Target Impacts.” Journal of Insect Science 3: 32, 2003. Published online, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC524671/.

n Red Imported Fire Ant Also known as: RIFA Scientific name: Solenopsis invicta Order: Hymenoptera Family: Formicidae Native Range. South America. Red imported fire ants come from a narrow strip extending from Porto Velho, Brazil, northwestward to Santa Fe, Argentina. Genetic studies suggest northeastern Argentina as the most likely source area of fire ants in the United States. Distribution in the United States. Imported red fire ants can be found across the southeastern United States. They occur from southeastern Virginia and eastern and southern North Carolina across the Gulf states and eastern Texas. Isolated populations occur in parts of Maryland, Tennessee, Arkansas, Oklahoma, New Mexico, and California. They are likely to spread through southwestern Texas to southern Arizona and from southern California north along the Pacific coastal region into northern California and Oregon. The ants also occur in Puerto Rico and the U.S. Virgin Islands. Description. Red imported fire ant colonies produce three types of workers, all sterile females and distinguished from other ants by their very aggressive behavior. The smallest, the so-called “minor workers,” are about 0.1 in. (1.6 mm) long and the largest, comprising about 35 percent of a mature colony, the “major workers,” are about 0.25 in. (6 mm) long. Intermediate in size are the many “media workers.” These ants are reddish to dark brown. The waist (pedicel) has two segments, and all workers possess a stinger at the end of their black bulbous abdomens (gaster). Winged females and males, known as “reproductives,” are both about 0.34 in. (8.8 mm) long. Each colony will have one or more queens, also about 0.34 in. (8.5 mm) long. Red imported fire ant mounds occur in open areas and are rarely more than 18 in. (45 cm) in diameter or 16 in. (40 cm) high. They are hard and have no visible entrances. Those built in clay soils are typically symmetrical domes, while those constructed in sandy soils are irregularly shaped. However, in some circumstances, no mounds are evident. In urban and suburban areas, they may nest under concrete slabs, in the walls of buildings, or in electrical equipment. Related or Similar Species. Among the many fire ant species that live in the United States, three other members of the genus Solenopsis are also pests. Separating one from another is difficult and requires a sample size of 40 or more workers for proper identification even by experts. The black imported fire ant (S. richteri) is limited in its distribution, found only in a small part of northern Mississippi and Alabama. It is displaced by and may actually be a subspecies or regional variant of the red imported fire ant. The southern fire ant (S. xyloni) is native to the Southeast. Nests are often built under stones or boards or at the bases of plants. The nest usually appears as loose soil with many craters spaced over an area of 2–4 sq. ft (0.18–0.37 m2). The tropical fire ant (S. geminata) is another native species of the

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southeastern United States. Tropical fire ant workers have square heads that are large in proportion to their bodies. Their mounds are often built around clumps of vegetation. Introduction History. Imported red fire ants were introduced to the United States through the port of Mobile, Alabama, in the mid-1930s. Genetic studies trace the origins to 9–20 queens and (presumably) their workers. A secondary introduction may have occurred 60 miles to the west of Mobile. From these pioneers, populations spread to other southeastern states. They arrived in Virginia in 1989, and were discovered in Los Angeles, Orange and Riverside counties, California, in 1998. In single-queen colonies, growth is outward at a rate no more than 40 m per year. In multi-queen colonies, dispersal of winged reproductives covers greater distances. Most new colonies form within a mile of the reproductives’ birthplace, but some may be 10 miles or more distant. Nonetheless, most Top: The red imported fire ant is native to South America. Bottom: The of the range expansion in the red imported fire is invasive in the Gulf States and east Texas and United States is probably the expected to expand its range in coming years. It has also been result of human actions. Ants introduced into Puerto Rico. (Adapted from USDA Agricultural Research are spread when mated females Service map, 2007. http://www.ars.usda.gov/fireant/Imported.htm.) are transported in sod, hay, the root balls of ornamental plants, and on earth-moving equipment. Habitat. Red imported fire ants are most often associated with disturbed habitats such as agricultural fields, pastures, lawns, and other open, sunny sites. Rarely do they occur in natural forests or similar well-shaded locations. These ants are limited by cold temperatures and climates receiving less than 20 in. (510 mm) of precipitation a year. In dry regions, however, they can exist by colonizing areas near permanent sources of water or areas regularly irrigated. Red imported fire ants can regulate their microclimate to a degree by moving their broods to higher and lower levels of their mounds, which may extend as much as 4 ft. (1.2 m) below the ground. Diet. Red imported fire ants are omnivores. They are voracious predators of other arthropods, but also consume emerging seedlings of field and truck crops such as soybeans, eggplant, cucumbers, corn, okra, and a host of others. They are known to chew the bark of

154 n INVERTEBRATES (INSECTS) citrus trees and eat fruits. In homes, they prefer oily and greasy foods high in protein. These ants also tend aphids and consume honeydew. Worker ants can only swallow liquids. Solids are cut to a manageable size and carried back to the nest to be fed to larvae. The larvae digest the food and regurgitate a protein-rich brew that feeds the workers and queen. The workers also regurgitate what they have swallowed so that their nest mates can lick or suck it up. Life History. Biological patterns for fire ants must be The waist of the red imported fire ant has two distinct segments. All described in terms of both the workers have a stinger at the end of the abdomen. (Eli Sarnat.) individual and the colony, since the latter is the essential social unit. The individual’s life cycle begins as an egg. A grub-like legless larva hatches in 8–10 days and begins the major growth stage of the individual. It periodically sheds its skin as it grows larger, and becomes a pupa with legs in 6–12 days. The pupal phase lasts another 9–16 days, after which time adult sterile workers emerge and begin foraging or reproductives emerge, take flight, and mate some 300–800 ft. (90–240 m) up in the air. The complete transition from egg to adult takes 22–38 days. A colony begins life when a mated female descends to the earth, breaks off her wings, and digs a founding nest 2–5 in. (5–12 cm) straight down into the ground. She seals herself off and lays 12–14 worker eggs. It takes about a month for these eggs to develop into adults. During this period, the queen does not feed, but she nourishes the larvae with sterile eggs, regurgitated oils, and salivary secretions. These workers will be the smallest in the colony cycle and are called “minims.” They open the nest, forage for food, rear a new group of workers, and feed the queen. The queen becomes essentially an egg-making machine and can produce 200 eggs a day. As the colony grows, more foragers (10–20% of total workers) mean more food, and a larger proportion of larvae become majors. At the end of its second year, a colony matures and produces winged reproductives. The colony at that time averages 27,000 workers. Very large mature mounds may house 240,000 workers. Minor workers live 1–2 months, media workers 2–3 months, and major workers 3–6 months. Queens live 2–6 years. Impacts. Red imported fire ants are mainly feared for their bites. Their venom creates a burning pain in the victim and, within 24 hours, raises itching pustules on the skin. These aggressive ants swarm over anything disturbing their nests, so bites are multiple. For sensitive people, bites can result in anaphylactic shock and, rarely, death. Increasingly, red imported fire ants are invading homes, outdoor electric meters and air conditioners, traffic control boxes, and airport runway lights, increasing opportunities for human-ant interaction, interfering with switching mechanisms, and causing short circuits and shutdowns. Infestations of red imported fire ants also pepper lawns and parks with unsightly mounds.

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Fire Ants Leave the United States for Distant Shores

S

ince 2000, red imported fire ants have invaded China, Taiwan, and Australia. The southern United States appears to be the source of these invasions. Recent genetic studies indicate two or more introductions to each area have occurred. The ants that arrived in Taiwan stem directly from populations in California; however, California received its fire ants from southern U.S. states. American populations carry distinct combinations of genes (haplotypes) that are extremely rare in South America but common in the United States, Asia, and Australia and allow the invasion history of the ants to be tracked. Hitchhikers in cargo, fire ants appear to be following the world’s major trade routes to new locales. Source: Ascunce, Marina S., Chin-Cheng Yang, Jane Oakey, Luis Calcaterra, Wen-Jer Wu, Cheng-Jen Shih, Je´roˆme Goudet, Kenneth Ross, and DeWayne Shoemaker. “Global Invasion History of the Fire Ant Solenopsis invicta.” Science 331: 1066–68, 2011.

In agricultural fields, mounds can damage farm equipment. Ants feed on young shoots, protect aphids that feed on plants, and can interfere with root growth; many crops suffer significant damage where ant colonies occur. On the other hand, red imported fire ants are major predators of pests such as boll weevils, sugarcane borer, and ticks. It is credited with reducing the range of the lone star tick, which targets livestock. In more natural settings, the red imported fire ant is a strong competitor of native ants, especially the tropical fire ant; and displaces the invasive Argentine ant (Linepithema humile). It has been implicated in the decline of the bobwhite (Colinus virginianus) in the southeastern United States and has negatively impacted other ground-nesting birds and reptiles through bites, predation, and competition for space and food. Management. Poisonous baits have proven most effective in reducing or eliminating colonies, since red imported fire ants carry food back to their nests. Boiling water poured on individual mounds may help reduce populations, but area flooding only causes the ants to link together in rafts and disperse. Biological controls hold promise, particularly the use of the nematode Neoaplectana carpocapsae and parasitic phorid flies that lay their eggs in ants. Spread of the ant is being slowed with the establishment of quarantine areas. Ant-proofing structures can prevent the entry of ants to buildings. Caulking and sealing all cracks and crevices keep ants out, since they usually nest outdoors and enter homes only to feed. Generally sanitizing outdoor areas through the frequent emptying of trash cans and dumpsters also discourages foraging ants.

Selected References Apperson, Charles, and Michael Waldvogel. “Red Imported Fire Ant in North Carolina.” Insect Note_ENT/rsc-35, Department of Entomology, North Carolina Cooperative Extension, n.d. http:// www.ces.ncsu.edu/depts/ent/notes/Urban/ifa.htm. Collins, Laura, and Rudolf H. Scheffrahn. “Red Imported Fire Ant.” Featured Creatures, Department of Entomology and Nematology, University of Florida, Institute of Food and Agricultural Sciences, 2008. http://entnemdept.ufl.edu/creatures/urban/ants/red_imported_fire_ant.htm.

156 n INVERTEBRATES (INSECTS) “Integrated Pest Management Manual: Fire Ants.” National Park Service, U.S. Department of the Interior, 2010. http://www.nature.nps.gov/biology/ipm/manual/fireants.cfm. IUCN/SSC Invasive Species Specialist Group. “Solenopsis invicta (Insect).” ISSG Database, 2006. http:// www.issg.org/database/species/distribution.asp?si=77&fr=1&sts=&lang=EN. “Red Imported Fire Ant Pest Profile.” California Department of Food and Agriculture, 2010. http:// www.cdfa.ca.gov/phpps/pdep/target_pest_disease_profiles/rifa_profile.html.

n Vertebrates n Fish n Alewife Also known as: Big eye herring, freshwater herring, gray herring, kyack, sawbelly, white herring, branch herring, river herring, glut herring, mulhaden, golden shad Scientific name: Alosa pseudoharengus Synonym: Pomolobus pseudoharengus Family: Clupeidae Native Range. Native to the Atlantic Ocean from Red Bay, Labrador, to South Carolina; spawning in estuaries and Atlantic Slope rivers of the eastern United States as much as 100 miles inland. Distribution in the United States. As a native transplant, it is established in all five Great Lakes and also reported in streams, landlocked lakes, and reservoirs in Colorado (headwaters of the Colorado River basin), Georgia (Savannah River), Kentucky (Ohio River), Indiana (Bass Lake), Maine (Belgrade Lakes), Nebraska (Merritt Reservoir, Ainsworth Canal), New York (Lake Otsego, Cayuga, Upper Saranac, Big Moose, Woodhull, Saratoga, and Seneca lakes; St. Regis headwaters, mountain lakes in Adirondacks), Pennsylvania (Delaware Gap National Recreation Area), Tennessee (Dale Hollow Reservoir, Watauga Reservoir), Vermont (Lake St. Catherine), Virginia (Claytor Lake, John W. Flanagan Reservoir, Lake Chesdin, Leesville Reservoir, Smith Mountain Lake), West Virginia (Bluestone Reservoir, New and Kanawha rivers), Wisconsin (Kangaroo Lake, Pigeon River, Pigeon Lake, East Twin River, Sheyboygan River, Green Bay, St. Louis River estuary, Sauk Creek, and Milwaukee River). Description. The transplanted, landlocked alewife is smaller than the native anadromous alewife and typically reaches a length of 6–10 in. (15–25 cm) and weight of less than 4 oz. (0.11 kg). The body is laterally compressed and relatively deep. It has a silvery color with a darker greenish sheen on the back. A distinctive black dot occurs on the body behind the eye. Scales merge along the belly to form scutes that create a serrated edge, the reason for one of the fish’s common names, sawbelly. The tail or caudal fin is forked. Alewives move in large schools. Introduction History. Alewives were first reported from Lake Ontario in 1873. Some have suggested they are actually native to the lake, having migrated up the St. Lawrence River from the Atlantic Ocean at some earlier time in geologic history. Another possible route for entry to the Great Lakes was the Erie Canal, opened in 1825 to connect Lake Erie with the Hudson River and the Atlantic Ocean. The alewife was first recorded from Lake Erie in 1831. The fish slowly dispersed upstream, perhaps aided by the Welland Canal, which connects Lakes Ontario and Erie. Populations were established in Lake Huron by 1933, Lake Erie by 1940, Lake Michigan by 1949, and Lake Superior by 1954. Genetic information suggests that alewives arrived via the Erie Canal and are not descendants of a population native

158 n VERTEBRATES (FISH) to Lake Ontario. The fish is now abundant in Lake Huron and dominant in Lake Michigan. Its numbers are held in check in Lake Superior by cold water and in Lake Erie by water too shallow to provide many overwintering refuges. Invasion of the Great Lakes was aided by prior overfishing of its major predators, Atlantic salmon and lake trout. The introduction of the sea lamprey (see Fish, Sea Lamprey) may also have reduced the population sizes of competitors. Equally important, alewife physiology was such that they could thrive in the landlocked freshwater habitats to which they were introduced without the need to return to the sea after spawning, part of the natural life cycle of populations in their native range. In water bodies other than the Great Lakes, all introductions were intentional, through both legal (e.g., in Virginia and West Virginia) and illegal (e.g., Lake Otsego and Adirondack Top: The alewife is native to the western Atlantic Ocean, from Labrador lakes in New York and Lake St. south to South Carolina. In its native range it is anadromous. Bottom: Catherine in Vermont) stocking As a native transplant, the alewife is established in all of the Great Lakes of streams and lakes with forage and in streams, lakes, and reservoirs in several states. (Both maps fish. adapted from Fuller, Maynard, and Raikow 2009.) Habitat. Temperate lakes, reservoirs, and rivers. They prefer the deeper waters of lakes by day and move into shallower waters near shore at night. Alewives spawn in shallow waters and tributary streams in the spring. They overwinter in the deepest parts of lakes, but extremely cold winters may cause die-offs. Diet. Primarily a filter-feeder, the alewife consumes zooplankters such as copepods. However, they are generalists and also feed on insect larvae, fish eggs, and small fish fry. Life History. Alewives spawn in the spring during the night. Each female produces 12,000–50,000 eggs, each about 0.9 mm in diameter; they are broadcast as the males release sperm. Eggs are deposited over all types of substrate. No parental care is invested in eggs or larvae; the adults leave the spawning grounds as soon as spawning is completed. The larvae hatch after 3–6 days, depending upon water temperature; and 3–5 days after that they begin to feed. Larvae transform into juvenile fish slowly. Landlocked fishes mature in 1–3 years,

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faster than native anadromous members of the species. They live fewer than 10 years. Mass die-offs occur periodically, usually in the spring. Alewives are prey for many predators, including native lake trout (Salvelinus namaycush), eels (Anguillidae), bigmouth bass (Micropterus salmoides), and whitefish (Coregonus spp.). Herons and other fish-eating birds take alewives, as do semiaquatic mammals such as otter and mink. Impacts. Alewives transformed the Great Lakes ecosystem. In some parts of the lakes, Transplanted alewives inhabit landlocked lakes, reservoirs, and streams. (Eric Engbretson.) they are now a keystone species. In Lake Michigan, 70–90 percent of the fish, by weight, are alewives. They outcompeted native zooplankton-feeders and are blamed for the demise of the lake trout in Lake Michigan, once a mainstay of the lake’s commercial fishery. Their preying on fish fry is implicated in declines of emerald shiner (Notropis atherinoides), yellow perch (Perca flavescens), deepwater sculpin (Myoxocephalus thompsoni) and burbot (Lota lota). In smaller bodies of water, they compete with yellow perch, rainbow smelt (Osmerus mordax), and young bass, all of which survive on zooplankton. Alewives may also interfere with reproduction in landlocked Atlantic salmon (Salmo salar) and lake trout in areas where alewives are the main prey species: Alewives have a high amount of the enzyme thiaminase, so that the eggs of their predators become deficient in thiamine, resulting in high mortality rates among the fry. Alewives are so well established in the Great Lakes ecosystem that their removal at this point would be disruptive. Instead, they are seen as a boon to efforts to reestablish an important native game fish in the lakes, the Atlantic salmon, for which they serve as an important forage species. Pacific Chinook salmon (Oncorhynchus tshawytscha) and coho salmon (Oncorhynchus kisutch) have been introduced to Lake Michigan to help control alewives and to provide a sport fishery. Mass die-offs, such as occurred during the 1960s in the Great Lakes, polluted the beaches with rotting fish and were both nuisances and health hazards. In other waters, where alewives are more recent invaders, they have the potential to alter the food web and reduce biodiversity. Management. Population reduction is the only option available in the Great Lakes, where the alewife is a permanent addition to the fish fauna, and eradication might actually cause more damage to the ecosystem. Reestablishment of the Atlantic salmon and the stocking of other predatory fish such as Pacific salmon and brown trout (Salmo trutta: see Fish, Brown Trout), itself an exotic species, may help control alewife numbers. Elsewhere, culling extant populations and the prevention of new introductions are essential to reduce threats to native ecosystems. Legislation and enforcement of laws that make transport of alewives illegal are important. Construction of net barriers to prevent downstream dispersal out of lakes has been suggested. In some instances, fishing of alewives and collecting them when they

160 n VERTEBRATES (FISH) congregate on spawning or overwintering grounds have been recommended. Alewives are sometimes used for bait and for pet food.

Selected References Bean, Tim. “Alewife (Alosa pseudoharengus).” Introduced Species Summary Project, Columbia University, 2002. http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/inv_spp_summ/ alewife.html. Fuller, Pam, Erynn Maynard, and David Raikow. “Alosa pseudoharengus.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2009. http://nas.er.usgs.gov/queries/FactSheet.asp ?speciesID=490. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Alosa pseudoharengus (Fish).” ISSG Global Invasive Species Database, 2005. http:// www.issg.org/database/species/ecology.asp?si=625&fr=1&sts=&lang=EN. Tobias, V., and W. Fink. “Alosa pseudoharengus.” Animal Diversity Web, University of Michigan Museum of Zoology, 2004. http://animaldiversity.ummz.umich.edu/site/accounts/information/ Alosa_pseudoharengus.html.

n Asian Swamp Eel Also known as: Rice eel, rice-paddy eel, belut, white ricefield eel, yellow eel. Scientific name: Monopterus albus Synonym: Fluta alba Family: Synbranchidae Native Range. Indian subcontinent, Southeast Asia, East Asia. It is also native to Central and South America and may be native to Australia. Distribution in the United States. Florida (North Miami area, Little Manatee River and Bullfrog Creek drainages near Tampa, and a canal system near Homestead, South Miami– Dade County); Georgia (Chatahoochee Nature Center, Roswell, Fulton County; Chattahoochee National Recreation Area, Gwinnett County); Hawai’i (O’ahu), and New Jersey (vicinity Silver Lake, Gibbsboro, Camden County). Description. Asian swamp eels have elongated bodies and a compressed, tapering tail. They lack scales and fins and are covered with mucous. A single V-shaped gill opens on the underside just behind the head. The nose is blunt, and the eyes are small and dark. The upper lip is thick and covers part of the lower lip. Teeth are bristle-like (villiform). Body color ranges from olive green to brown; some are spotted with flecks of gold, yellow, or black. Total length is about 3 ft. (1 m); adults weigh about 1 lb. (0.5 kg). Related or Similar Species. Asian swamp eels are not true eels, but they may be mistaken for native American eels (Anguilla rostrata). True eels have scales and fins and are anadromous. Asian swamp eels also resemble sea lampreys (see Fish, Sea Lamprey), which have obvious dorsal and caudal fins and seven gill openings on each side of the head. Lampreys lack jaws and have oval-shaped mouths. In Florida, Asian swamp eels might be confused with two large native aquatic amphibians, the two-toed amphiuma (Amphiuma means) and the greater siren (Siren lacertina). The former have four tiny legs and the latter have small front legs and bushy external gills. Introduction History. Asian swamp eels were in Hawai’i by 1900. They were likely deliberately introduced for food. Swamp eels are a common food fish in China and other parts of Asia, where they are sold live. It is likely that immigrants brought them to Hawai’i. The first

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reports of swamp eels occurring in Florida and Georgia stem from the 1990s; these may have been accidentally released from fish farms or intentionally “freed” by aquaria owners. In Florida, two populations (North Miami and Tampa) can be genetically traced to China, and the third (South Miami–Dade County) to Southeast Asia. The Georgia population stems from Japan or Korea, which may be why it is cold-tolerant. Habitat. Swamp eels are freshwater creatures and prefer shallow (less than 10 ft. or 3 m deep) sluggish, even stagnant waters. They are found in ponds, reservoirs, wetlands, streams, canals, and ditches. Swamp eels can survive relatively wide temperature ranges and tolerate cold, even freezing, temperatures. They also are able to withstand low oxygen levels in water since they can “breathe” through their skin. During periods of drought, they can remain burrowed in damp mud for weeks without eating. Their adaptability to a wide Top: The so-called Asian swamp eel is native not only to Asia, but to range of ecological conditions Central and South America as well. It may also be native to Australia. extends to brackish and saline Bottom: The Asian swamp eel is established in several widely separated water, and they can even crawl locations in the United States, where it has apparently been introduced across land if moist enough. as a food fish. (Adapted from Nico and Fuller 2009.) During the day, Asian swamp eels burrow in wet mud or hide in crevices or beneath dense vegetation. Diet. Nocturnal predators, swamp eels consume a variety of animals, including oligochaete worms, aquatic insects, amphipods, crayfish, tadpoles, frogs, turtle eggs, fish eggs, and other fish. They also eat detritus. Life History. Asian swamp eels go through their complete life cycle in freshwater. Reproduction has been reported throughout the year. Eggs are laid in floating bubble nests near the mouths of burrows and are guarded by males. All young hatch as females, but some mature females are transsexual and transform into males after a yearlong nonfunctional stage. The males are larger than the females. Impacts. To date, negative impacts on native ecosystems are more of a threat than a reality. Their broad range of tolerances, diet, and ability to move over land give Asian swamp

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A. Adult Asian swamp eel. (U.S. Geological Survey.) B. Close-up of head. (U.S. Geological Survey.)

eels the potential to be aggressive invasive organisms. Furthermore, they have no known predators in the United States. Their burrowing habits and nocturnal activity periods could allow them to spread without being detected. They might reduce populations of native prey species as well as native predators such as large fish, frogs, turtles, and wading birds that compete for the same food source. A major concern is that they will invade Everglades National Park. The Homestead, Florida, collection site is only 0.5 mi. (0.8 km) from the park. Management. Because of their ability to breathe air, control by usual fish eradication methods of poisoning water is difficult. Electrical barriers may prevent movement to new areas. Removal of vegetation could help. Electro-fishing devices are the only way to capture and detect Asian swamp eels for research and monitoring. The best practice is prevention: Do not stock these fish; do not release pet aquarium eels (or any other organisms) into local waters; and do not transport them as bait, forage, or aquarium pets.

Selected References Bricking E. M. “Asian Swamp Eel.” Introduced Species Summary Project, Columbia University, 2002. http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/inv_spp_summ/Monopterus _albus.html. Hamilton, H. Frequently Asked Questions about the Asian Swamp Eel. Florida Integrated Science Center, Gainesville, FL: USGS, 2006. http://fl.biology.usgs.gov/Nonindigenous_Species/Swamp_eel_FAQs/ swamp_eel_faqs.html. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Ecology of Monopterus albus.” ISSG Global Invasive Species Database, 2005. http:// www.issg.org/database/species/ecology.asp?si=446&fr=1&sts. Nico, Leo, and Pam Fuller. “Monopterus albus.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2009. Revised November 17, 2008. http://nas.er.usgs.gov/queries/FactSheet.asp ?speciesID=974. Rotham, Carly J. “Asian Swamp Eel Threatens N.J. Wildlife,” New Jersey Real-Time News, 2008. http:// www.nj.com/news/index.ssf/2008/09/asian_swamp_eel_threatens_nati.html.

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n Bighead Carp Scientific name: Hypophthalmichthys nobilis Synonym: Aristichthys nobilis Family: Cyprinidae Native Range. China, where it is native to lowland rivers of the North China Plain and South China, including the Yangtze (Chiang Jiang), Pearl, and West Xi Kiang. Distribution in the United States. Established in the middle and lower Mississippi and Missouri rivers, in Illinois and Missouri. It may also be established in the Tallapossa Drainage in Sougahatchee Creek and Yates Reservoir, Alabama; in the Big Muddy, Cache, and Kaskaskia rivers in Illinois; and in a backwater outlet of the Black River, Louisiana. It has been reported in Arizona, Arkansas, California, Colorado, Florida, Hawai’i, Indiana, Iowa, Kansas, Kentucky, Louisiana, Mississippi, Nebraska, Oklahoma, South Dakota, Tennessee, Texas, Virginia, and West Virginia. Description. Bighead carp are deep-bodied, laterally compressed fish with, as their name implies, very large heads. A complete lateral line arcs ventrally in the anterior part of the body. Scales on the body are tiny; the head and opercle are scaleless. Body color is dark gray on top and off-white on sides and belly. Mature specimens have dark grayish blotches on the top of the body. Young up to eight weeks old are silvery. On the underside, a distinct, smooth keel runs from near the base of the pectoral fins to the vent. The large upturned mouth has bony, rigid lips without barbels; the lower jaw protrudes slightly beyond the upper one. There are no teeth in the jaws. The eyes are close to the mouth and lie on Top: The bighead carp is native to the lowland rivers of eastern China. the body midline. Fins of small Bottom: Bighead carp are invasive in the Mississippi-Missouri River sysindividuals lack spines, but large tems and are reported in a number of other waterways. (Adapted from specimens have a heavy, stiff, Nico and Fuller 2009.)

164 n VERTEBRATES (FISH) non-serrated spine at the origin of the dorsal fin, which has 8–9 soft rays. A slightly stiffened spine appears at the origin of the anal fin, which is hooked and has 13–14 soft rays. Pectoral fins on large males have sharp, nonserrated ridges along several of the anterior rays. The gill rakers are long and closely spaced, but are not fused together. The pharyngeal tooth count is 4–4. Large individuals may be more than 4 ft. (1.2 m) long and weigh over 100 lbs. (45 kg). Males are larger than females. Related or Similar Species. Silver carp (Hypophthalmichthys molitrix), another invasive Asian carp (see Fish, Silver Carp), is a close relative and occurs in many of the same places as bigheads. The silver carp has a longer keel that runs from the base of the anal fin to the isthmus at the base of the gills. Its body color is greenish dorsally and silvery below the midline; it lacks the blotches of mature bigheads. The anal fin has 12–13 rays, and pectoral fins have 15–18 rays and a hard spine with serrated rear margin. Bighead carp can exceed 4 ft. in length and weigh more than 100 lb. (U.S. Gill rakers are fused into a plate Geological Survey.) and covered with a net-like, porous matrix with which they strain the smaller phytoplankton from the water. Silver carp are somewhat smaller than bighead carp, attaining a length of 3 ft. (1.0 m) and a weight of 60 lbs. (27 kg). Silver carp are known for leaping high into the air when disturbed. Juvenile bigheads can be confused with gizzard shad (Dorosoma cepedianum; see Fish, Gizzard Shad), often used as bait fish. Introduction History. Both bighead and silver carp were imported into Arkansas in 1972 by a catfish farmer interested in their potential for improving water quality in his fish ponds by their ability to consume huge amounts of algae. The fish spread to other aquaculture operations for the same purpose. Carp first appeared in the open waters of the Ohio and Mississippi rivers in the early 1980s; they probably escaped from culture ponds. Thousands of bighead carp made their way into the Osage River, Missouri, when a fish hatchery near Lake of the Ozarks was inundated by floodwaters in April 1994. Fish that had escaped into the Missouri River multiplied and spread into the lower Kansas River in Kansas after 1990.

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Hojo-e

B

ighead carp are a food fish for some Asian Americans and are usually purchased live at markets in large cities such as Chicago and New York. Cultural practices among Chinese, Vietnamese, and other Asian immigrant groups could provide a potential pathway for the fish to enter the Great Lakes. As part of a Buddhist ceremony known as hojo-e, releasing captive animals secures merits for the afterlife and lengthens the life of the practitioner. The ritual commonly takes place at Buddhist temples under the guidance of monks. In the United States, goldfish, turtles, and birds are usually released, but the practice may explain the appearance of Asian carp in public ponds and lagoons in the Great Lakes region. Chicago and New York now both have regulations requiring that Asian carp be killed before they are sold. Source: Higbee, E., S. Fellow, and K. G. Shwayder. “The Live Food Fish Industry: New Challenges in Preventing the Introduction and Spread of Aquatic Invasive Species.” Great Lakes Panel on Aquatic Nuisance Species, ANS Update 10(2): Fall–Winter 2004. Online at http://www.glc.org/ans/ansupdate/pdf/2004/ANSUpdateFW.pdf.

Illegal introductions by commercial fish farmers in the late 1980s are responsible for carp in Grand River, Oklahoma; California; and Cherry Creek Reservoir, Colorado. Habitat. Bighead carp are native to subtropical and temperate freshwater habitats, preferring large rivers and the lakes connected to them. They usually are found in the upper or euphotic layer of the water column, where food is most abundant. They may migrate up streams from lakes to spawn, since they require a current for their eggs to float and develop properly. Diet. Bighead carp filter relatively large particles (10–100 μm) from the water. As plankton feeders, their diet changes as they grow. Larvae consume mostly small phytoplankters such as protococcaceans and cyanobacteria; but large individuals specialize on larger particles, including zooplankters such as cladocerans and midge larvae and algae such as diatoms and colonial phytoplankters. They are opportunistic feeders, however, and what they eat depends upon the type of suspended materials that are most abundant. They have been said to consume their weight in plankton each day. They also feed on detritus. Life History. Males and females mature in 2–4 years in warmer, subtropical waters and 5–7 years in cooler, temperate waters. They are prolific breeders, with females producing up to a million eggs during their lifetimes. Eggs have diameters near 0.2 in. (4.5–5 mm). Spawning takes place in the spring as water levels in rivers rise. Adults may migrate 100 miles or more upstream to breed. Eggs and larvae then float downstream to the lower reaches of rivers and to lakes. Intolerant of brackish water, carp spend their entire lives in freshwater. Impacts. As voracious plankton and detritus feeders, bighead carp can outcompete native filter-feeding organisms such as mussels, fish larvae, and some adult fishes. The adult fish most likely to suffer from carp invasions are paddlefish (Polydon spathula), bigmouth buffalofish (Ictiobus cyprinellus) and gizzard shad (Dorosoma petense). Bighead carp have the potential of disrupting entire aquatic food webs. Their introduction into the Great Lakes system is particularly feared for this reason.

166 n VERTEBRATES (FISH) Management. The main focus of management is preventing the introduction of bighead carp into the Great Lakes. They already inhabit the Illinois River, which connects to Lake Michigan via the Chicago Sanitary and Ship Canal. By 2011, the U.S. Fish and Wildlife Service, the EPA, the U.S. Army Corps of Engineers, the State of Illinois, the International Joint Commission, and the Great Lakes Fishery Commission had completed a multimillion-dollar series of three electric dispersal barriers on the canal.

Selected References “Asian Carp: Key to Identification.” U.S. Fish and Wildlife Service, 2002. http://www.fws.gov/ Midwest/fisheries/library/broch-asiancarpkey.pdf. Bighead and Silver Carp (Hypophthalmichthys nobilis and H. molitrix). Wisconsin Department of Natural Resources, 2004. http://dnr.wi.gov/invasives/fact/asian_carp.htm. Nico, Leo, and Pam Fuller. “Hypophthalmichthys nobilis.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2009. Revised November 10, 2010. http://nas.er.usgs.gov/queries/ FactSheet.asp?speciesID=551. U.S. Army Corps of Engineers, Chicago Sanitary and Ship Canal Aquatic Nuisance Species Dispersal Barrier System, 2009. http://www.lrc.usace.army.mil/AsianCarp/BarriersFactSheet.pdf.

n Brown Trout Also known as: German trout Scientific name: Salmo trutta Synonyms: Salmo fario, Fario argenteus Family: Salmonidae Native Range. Eurasia. In Europe, this anadromous fish is native to Atlantic, Baltic, and Black Sea and Caspian Sea drainages. In western Asia, it is reported as native to Afghanistan, Armenia, and Turkey. It is also considered native in parts of North Africa. The fish has been introduced into areas where it is not native on every continent except Antarctica. Those imported into the United States came from Germany. Distribution in the United States. The brown trout has been introduced into almost all 50 states and the Commonwealth of Puerto Rico. The only states without brown trout are Alaska, Louisiana, and Mississippi. The fish may not be breeding in most states, but it is continually restocked for recreational fishing. Description. Brown trout are so named because of their brown to golden-brown color. The sides are yellow or silvery and bellies white to yellow. Red spots with blue halos and black spots adorn the sides of stream-dwelling browns, but are faint on lake-dwelling individuals. The lateral line is iridescent when light hits it from the right angles. There are two dorsal fins, the rear one a small fatty (or adipose) fin with a reddish color. The anal fin has 9–10 rays. The tail is square. Adults in the United States can be 13–16 in. (33–40 cm) long and weigh up to 10 lbs. (4.5 kg). Related or Similar Species. Atlantic salmon (Salmo salar) are close relatives. They have no red on the adipose fin and the tail is slightly forked. Rainbow trout (Onchorhynchus mykiss) have lines of black spots on the tail (see Fish, Rainbow Trout, for a fuller description). Introduction History. Brown trout were first imported from German hatcheries into the United States in 1883, when a shipment of 80,000 eggs landed at Cold Spring Harbor, New York. These eggs were distributed by the U.S. Fish Commission to the Caledonia Fish

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hatchery in New York and the Norville Hatchery in Michigan. In 1886, Pennsylvania began stocking brown trout in streams where native brook trout populations had been extirpated or reduced by practices such as logging, farming, dam construction, and industrial discharges, all of which had led to warmer water temperatures and siltation. Since then, brown trout have been stocked by state and local agencies across the country for sport fishing. Habitat. Although anadromous in its native range, brown trout in the United States are freshwater fish and prefer streams and lakes. They hide during the day in shallow beds of aquatic vegetation, in shallow rock-strewn areas, under submerged logs, or in deep pools. They are most active at dawn and dusk and when the water temperature is near 55°F (12.8°C). They generally prefer water temperatures between 65° and 75°F (18–24° C) and tolerate warmer water temperatures than do native brook trout. Top: The brown trout is native to Europe and western Asia. It has been Diet. Smaller individuals widely introduced throughout Eurasia, making delineation of the actual feed on insects such as mayflies, native range difficult. Bottom: Brown trout have been introduced for caddisflies, and midges that the sport-fishing in all states except Alaska, Louisiana, and Mississippi. stream carries to them. Larger (Adapted from Fuller, P. “Salmo trutta.” USGS Nonindigenous Aquatic brown trout have a broader diet Species Database, Gainesville, FL, 2009. http://nas.er.usgs.gov/queries/ speciesmap.aspx?speciesID=931.) that includes large aquatic insects, mayflies, caddisflies, crustaceans, snails, amphibians, and small fish. They actively hunt their prey primarily at night. Both small and large trout also consume detritus washed from the shore. Life History. Brown trout spawn from October to December in shallow headwater streams, ideally where the water is about 1 ft. (30 cm) deep, the current is about 7 in./second (18 cm/ second), and substrate particles are small (diameters of ca. 0.5 in. or 1.27 cm). The female hollows out a nest, or redd, in which to release her eggs. As she releases her eggs, the male releases milt to fertilize them. The female covers the fertilized eggs with sand and fine gravel, and both adults leave. The larvae stay in the redd for 2–3 weeks until they are about 0.1 in. (25 mm)

168 n VERTEBRATES (FISH) long. They then move downstream or into lakes for the first two years of their life. Brown trout begin to establish territories when they are juveniles. They mature at 3–4 years of age. Many populations in the United States are maintained through restocking efforts rather than natural reproduction. Impacts. Brown trout may compete with native fish, especially other salmonids (trout and salmon) for food. They Red spots with blue halos and black spots appear on brown trout but are grow larger and more rapidly than native species. They faint on lake-dwelling individuals. (Tramper/Shutterstock.) reportedly have also reduced populations of native trout through predation. As aggressive defenders of territories, they can displace native fishes from prime habitat. They have been implicated in population reductions of brook trout (Salvelinus fontinalis) and Modoc sucker (Catostomus microps), an endangered fish in California. Although it rarely happens, brown trout can hybridize with native trout. Brown trout has been nominated as one of “100 of the ‘World’s Worst’ invasive alien species” by the IUCN and Global Invasive Species Programme. Management. Brown trout are regularly stocked into most waters. Sport fishing often reduces numbers so that annual restocking is necessary. In New York, programs aimed at improving water quality for native brook trout become control methods for brown trout. In California, attempts are being made to eliminate brown trout where they may compete with golden trout (Oncorhynchus mykiss aguabonita).

Selected References “Brown Trout in Pennsylvania.” Pennsylvania Council of Trout Unlimited, n.d. http://www.patrout.org/ Documents/Reference/brown.pdf. Idema, A. “Salmo trutta.” Animal Diversity Web, Museum of Zoology, University of Michigan, 1999. http://animaldiversity.ummz.umich.edu/site/accounts/information/Salmo_trutta.html. Lauterbach, Sandra. “Brown Trout (Salmo trutta).” Introduced Species Summary Project, Columbia University, 2006. http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/inv_spp_summ/ Salmo_trutta.htm. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialty Group (ISSG). “Salmo trutta (fish).” ISSG Global Invasive Species Database, 2006. http://www.issg.org/ database/species/ecology.asp?si=78&fr=1&sts=sss&lang=EN.

n Gizzard Shad Also known as: Hickory shad, mud shad, nanny shad, skipjack, winter shad Scientific name: Dorosoma cepedianum Family: Clupeidae

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Native Range. Native to eastern and central North America in the Mississippi, Atlantic and Gulf coast drainage systems. Probably native in the Arkansas, South Platte, and Republican drainage systems in eastern Colorado. Possibly native to the St. Lawrence River and the Great Lakes. Distribution in the United States. The gizzard shad has been introduced to reservoirs and natural bodies of water both within and peripheral to its natural range. It is nonnative but established in the Colorado and Salt rivers and their connected reservoirs in Arizona; in the upper Colorado River drainage system in Arizona, Colorado, and Utah; and in Wyoming. Within its native range, its distribution has been extended by stocking in Colorado, Illinois, Indiana, Kansas, Kentucky, Minnesota, Nebraska, Pennsylvania, Utah, and Virginia. They may or may not be native to the Great Lakes, where they are found in all lakes except Lake Superior. Top: The gizzard shad is native to the eastern and central United States. Relatively recent natural range Bottom: Gizzard shad have been introduced to rivers, lakes, and expansion probably explains reservoirs within and beyond the borders of its native range. (Both maps their occurrence in Connect- adapted from Fuller 2009.) icut (Connecticut River), Maine (lower Saco and Kennebec rivers), Massachusetts (Connecticut and Merrimack rivers), and Vermont (Lake Champlain and Connecticut River). Description. This is a deep-bodied, moderately compressed herring that reaches lengths of 22 in. (56 cm) and weights of up to 7 lbs. (3.2 kg). It has a dark-blue or gray back, silvery sides that may reflect various colors, and a white belly. A dark, purplish blotch occurs high on the side behind the opercle in young and small specimens; it is faint or absent in older, larger individuals. It has no lateral line. The small mouth has a deep notch in the center of the upper jaw, which protrudes slightly beyond the lower jaw. The snout is blunt, and the eye large. The short, soft-rayed dorsal fin is centered on the back and has 10–12 rays; the last ray is a long filament that is distinctive for the species. The tail (caudal fin) is deeply forked. Scute-like scales form a distinct saw-toothed keel along the belly. Gill rakers are fine and

170 n VERTEBRATES (FISH) number more than 400. The stomach is thick-walled and acts like a gizzard, giving the fish its common name. Related or Similar Species. Threadfin shad (D. petense) is a smaller fish, rarely more than 8 in. (20 cm) long. The ray extending from its dorsal fin is much longer than that of gizzard shad and almost reaches the tail. The mouth especially distinguishes the two: in the threadfin, the lower jaw extends beyond the upper jaw—the reverse of the situation in gizzard shad. Fins of threadfin shad tend to be yellowish, whereas those of gizzard shad are grayish. Introduction History. In most cases, gizzard shad were intentionally introduced to ponds, lakes, and reservoirs as forage fish, especially in recreational sport fisheries. From their sites of entry, however, they have dispersed rapidly into connecting bodies of water, often assisted by man-made facilities. Gizzard shad in the Upper Colorado River basin of Arizona, Colorado, and Utah may trace their origins to an accidental introduction in a contaminated stocking of largemouth bass from a hatchery in Texas into Morgan Lake, New Mexico, near the San Juan River around 1996. Gizzards were first reported in the San Juan arm of Lake Powell in 2002 and are now found throughout the lake. From Lake Powell, they dispersed downstream to Lake Mead and, by 2008, were found in the Grand Canyon stretch of the Colorado River. They also dispersed upstream into the headwaters of the Colorado: in 2006 they were collected in the Gunnison and Middle Green rivers. Gizzard shad were stocked in Lake Havasu in the lower Colorado River drainage and, from there, have dispersed upstream as far as Davis Dam and downstream to the Mexican border and into the Salton Sea. In Connecticut, Massachusetts, and Vermont, gizzard shad have expanded their range upstream in the Connecticut River. They were first recorded at the mouth of the river around 1980, part of what seems to be a natural range expansion northward along coastal rivers, which has also brought them into the Merrimack River in Massachusetts and lower Saco and Kennebec rivers in Maine. By 1986, they had appeared at Holyoke Dam and now occur in the mainstem of the Connecticut River as far north as the Bellows Falls dam. Fish “ladders” built to let American shad (Alosa sapidissima) and Atlantic salmon (Salmo salar) circumvent the dams on their annual spawning runs have aided this movement. Gizzards entered Lake Champlain, Vermont, through the Hudson Barge Canal. Some believe gizzard shad may be native to the Great Lakes and St. Lawrence River, but it is also possible that they entered at Green Bay, Wisconsin, from the Mississippi River via the Fox-Wisconsin Canal or via the Chicago River Canal. Entry into Lake Erie was facilitated by the Ohio Canal. Gizzards in Wyoming stem from intentional introductions made in Nebraska. Habitat. Freshwater lakes and reservoirs, slow-moving rivers, and pools of smaller streams are preferred habitat. Gizzard shad can also be found in the brackish waters of estuaries. Native populations in the Mid-Atlantic states are anadromous. They often feed in schools over mucky and sandy bottoms. Diet. Gizzard shad are filter-feeders and, as adults, strain algae and detritus from bottom sands and muds. They also ingest sand to aid in grinding food in their gizzard-like stomachs. Young shad capture zooplankters (copepods and cladocerans) from the water column. Shad feed in large schools and characteristically leap from the water and flip onto their sides, a behavior that gave them the common name of skipjack. Life History. Gizzard shads spawn near shore during spring nights as water temperatures rise near 70°F (21°C). Spawning may continue for several weeks, after which adults return

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to deeper water. A single female may produce 300,000 or more eggs. Eggs and milt are broadcast near the surface in shallow water, and fertilized eggs settle down through the water and stick on roots, plants, and debris. They hatch in 2–3 days. Larvae grow rapidly and, during their first year, young shad may reach lengths of 4–7 in.—too large to be prey for all but the largest predatory fish. Most are sexually mature at age 2. Life span is 2–3 years. Adults experience die-offs in The gizzard shad, a member of the herring family, can attain a length of 22 in. and weigh as much as 7 lb. (Eric Engbretson.) winter and after spawning. Impacts. As larvae, gizzard shad may compete with the young of other, more desirable fish for zooplankton. Not only do shad populations grow rapidly, but they also spawn earlier than some other fish and thus may deplete the food resource enough to negatively affect growth and survival of sport and other fishes. They are usually stocked as a forage fish, but their rapid growth rate soon makes them too large to be taken by most predatory fishes. However, while they are small, they can be important prey for striped bass, largemouth bass, crappie, walleye, and other sport fishes. The closely related threadfin shad, also introduced to reservoirs as forage and baitfish, do not grow so large and so are favored by sport fisheries managers, but they too may be outcompeted by gizzard shad. In the Colorado River, gizzard shad are viewed as one more threat to endangered endemic fishes such as Colorado River pike minnow (Ptychocheilus lucius), bonnytail chub (Gila elegans), humpback chub (Gila cypha), and razorback sucker (Xyrauchen texanus) as well as to a number of other sensitive species. Management. Little to none.

Selected References Finney, Sam T., and Mark H. Fuller. “Gizzard Shad (Dorosoma cepedianum) Expansion and Reproduction in the Upper Colorado River Basin.” Western North American Naturalist 68(4): 524–25, 2008. “Fish Facts—Gizzard Shad.” U.S. Fish and Wildlife Service, Connecticut River Coordinator’s Office, n.d. http://www.fws.gov/r5crc/Fish/zc_doce.html. Fuller, Pam. Dorosoma cepedianum. USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2009. Revised March 10, 2008. http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=492. “Gizzard Shad Dorosoma cepedianum,” Utah Division of Wildlife Resources, n.d. http:// wildlife.utah.gov/pdf/AIS_plans_2010/AIS_12nGizzardShad-Dan-final.pdf. “Shad Species Used in Striped Bass Fishing.” Ben Sanders’ ArkansasStripers.com, n.d. http:// www.arkansasstripers.com/shad_species.htm. Steiner, Linda “Herrings,” Chapter 10 in Pennsylvania Fishes. Pennsylvania Fish and Boat Commission, 2000. http://www.fish.state.pa.us/pafish/fishhtms/chap10.htm.

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n Grass Carp Also known as: White amur Scientific name: Ctenopharyngodon idella Family: Cyprinidae Native Range. Native to eastern Asia, from the Amur River, Russia, to the West River in southern China. They have been widely distributed throughout the world as a food fish. The first imported into the United States reportedly came from Taiwan and Malaysia. Distribution in the United States. Grass carp have been widely used to control aquatic vegetation and have been reported from 45 states. States without records of grass carp are Alaska, Maine, Montana, Rhode Island, and Vermont. The fish is established in parts of the Mississippi River drainage, including the Mississippi River itself, in Arkansas, Kentucky, Illinois, Louisiana, Montana, and Tennessee; the Illinois River in Missouri, the lower Missouri River in Montana; the Ohio River in Illinois; and the Trinity River in Texas. Description. The grass carp is a large fish, often attaining a total length greater than 3 ft. (1.0 m) and a weight of 40 lbs. (18 kg) or more. It has a thick, oblong body with a rounded belly and broad head. The anal fin is set close to the caudal fin, which is forked. The dorsal fin is short, with 7–8 rays and set over the pelvic fins. All fins are soft-rayed and usually green-gray to dull silver. The lateral line is complete and slightly down-curved. Eyes are positioned at or slightly above midline of body. Body color is silver to pale gray, darker on the back and brassy on the sides. The large scales on the back and sides have distinct dark edges that give a characteristic cross-hatched pattern to the body. The pharyngeal teeth are long and serrated, with deep, parallel grooves. Gill rakers are short, unfused, and widely spaced. Related or Similar Species. Black carp (Mylopharyngodon piceus), another introduced Asian carp but one of much more restricted distribution in the United States, is darker in color, although not black. Its pharyngeal teeth are smooth and resemble human molars. It is a bottom-dwelling species that feeds on snails and other mollusks. All native cyprinids (minnows) have anal fins positioned more anteriorly than grass carp. Introduction History. Grass carp first entered the United States in 1963, when they were imported by the aquaculture program at Auburn University, Alabama, and the Fish Farming Experimental Station in Stuttgart, Arkansas. Fish escaping from the latter facility in 1966 were the first released into the White River, but later intentional stockings in Arkansas took place in lakes and reservoirs with free passage to river systems. Grass carp were reported in the Illinois section of the Mississippi River in 1971. Soon thereafter, grass carp were being commonly reported in the Mississippi and Missouri rivers. The fish has been widely dispersed since then through legal and illegal interstate transport and release by private individuals and organizations, escapes from farm ponds and aquaculture facilities, and stockings by federal, state, and local government agencies, among them the U.S. Fish and Wildlife Service, the Tennessee Valley Authority, and state fish and game agencies in Arkansas, Delaware, Florida, Iowa, New Mexico, and Texas. Habitat. Grass carp prefer shallow, quiet waters in lakes, pools, and the backwaters of large rivers that have abundant aquatic vegetation. They undertake long spawning migrations into faster-moving rivers. Diet. A herbivore, the grass carp feeds on algae, submerged and floating aquatic macrophytes, and even overhanging terrestrial plants. Although they are known to consume hundreds of different kinds of aquatic plants, they show distinct preferences. Young fish select

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soft, succulent species such as filamentous algae, pondweeds, elodea, duckweeds, chara, and the soft, growing tips of submerged plants. As they grow older and larger, they add more fibrous, less succulent plants and tend to avoid filamentous algae. Adults will eat such invasive plants as waterhyacinth (see Volume 2 Aquatic Plants, Waterhyacinth, Eichhornia crassipes), hydrilla (see Volume 2 Aquatic Plants, Hydrilla, Hydrilla verticillata), and Eurasian watermilfoil (see Volume 2, Aquatic Plants, Eurasian watermilfoil, Myriophyllum spicatum), especially if more palatable species are not present. They may also take insects and other invertebrates and detritus, particularly if it is attached to aquatic plants. Food consumption rates vary with water temperature, age and size of fish, and plant species available. Optimal consumption occurs when water temperatures are between 70° and 86°F (21–30°C). Carp feed only intermittently when tem- Top: The grass carp is native to eastern Asia. Bottom: Grass carp, peratures fall into the 30s introduced to control aquatic plants, have been reported from 45 states. (below 0°C). Essentially a (Adapted from Nico, Fuller, and Schofield 2009.) warm-water fish, they are dormant during the cold winters of temperate regions. Life History. Grass carp make long annual migrations to spawn in fast-moving large rivers. They often congregate in areas of turbulent water such as in rapids or at falls or the base of dams. Spawning occurs in the spring as water temperatures rise into the 60s and 70s (15– low 20s°C). The eggs must stay afloat in order to develop, which they do as they drift downstream, perhaps as much as 110 miles. Eggs hatch in 2–3 days, and larvae shelter in the vegetated areas of floodplains and lakes. They may winter in deep pools in rivers. Grass carp become sexually mature between two and five years of age in the subtropics and four to seven years or longer in cooler regions. Females usually mature a year later than males. Females produce 500,000–700,000 eggs, giving carp enormous reproductive potential. Impacts. Grass carp are stocked to remove aquatic weeds, many of which are also classified as invasive. This may be advantageous for some game fish, but overconsumption by

174 n VERTEBRATES (FISH) carp can also modify habitats and alter the species composition and trophic structure of ecosystems by eliminating the aquatic vegetation that provides food, breeding sites, and cover for native invertebrates, fishes, and birds. They may destroy The large, black-edged scales on the back and sides of grass carp give spawning substrates, disturb sediments and increase water them a distinctive appearance. (Oleg_Z/Shutterstock.) turbidity, increase nutrient levels in the water (their short gut makes their digestive system very inefficient, so large volumes of waste are produced), promote algal blooms, and decrease oxygen levels. Reportedly, they have contributed to reductions in populations of bluegill (Lepomis macrochirus), sunfish, smelt, and pike. Grass carp also have been implicated in the declining numbers of certain waterfowl such as Gadwall (Anas stepera), American Wigeon (Anas americana), and American Coot (Fulica americana) in areas to which the fish has been introduced. Carp may transmit several parasites and diseases to native fish. They are probably the source of the Asian tapeworm (Bothriocephalus opsarichthydis), which has infected some native cyprinids, including the endangered woundfin (Plagopterus argentissimus), a small minnow endemic to the Virgin River, a tributary of the Colorado River. Although considered an invasive species, grass carp is still stocked and even recommended as a biocontrol method for noxious weeds (see sidebar on Triploid Grass Carp). Management. All states have restrictions on the importation of grass carp for aquatic weed control, but most allow stocking with proper permitting. Because of the reproductive potential and propensity to disperse, and because of environmental concerns, sterile triploid fish (see sidebar on Triploid Grass Carp) are widely used today for weed control. Fish screens may be required at all inlets and outlets to a water body to prevent grass carp from migrating out of lakes and into rivers. Carp may or may not have the desired effect of removing aquatic weeds. They seem to be an all-or-nothing proposition and should be stocked only where complete elimination of submerged vegetation is desired or can be tolerated.

Triploid Grass Carp

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cientists have sought ways to reduce the likelihood of reproduction in grass carp and thereby control their spread into open waters. Crossing female grass carp with male bighead carp produced 100 percent triploid hybrids that were sterile. Triploid means each fish has three copies of each chromosome instead of the normal two (diploid). Later, it was discovered that shocking the eggs (in fish hatcheries) with cold or heat under high hydrostatic pressure also produced triploids, and this became the standard method of producing sterile fish. Since triploids have larger red blood cells and nuclei than diploids, the two are readily separated in a simple blood test. The U.S. Fish and Wildlife Service now has an established testing and inspection protocol to screen all fish leaving hatcheries and to guarantee that only triploids are imported into those states that do not permit the introduction of diploid grass carp.

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Selected References “Grass Carp, Ctenopharyngodon idella (Valenciennes 1844).” Florida Integrated Science Center, USGS, 2005. http://fl.biology.usgs.gov/Carp_ID/html/ctenopharyngodon_idella.html l. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Ctenopharyngodon idella (Fish).” ISSG Global Invasive Species Database, 2005. http:// www.issg.org/database/species/ecology.asp?si=369&fr=1&sts=sss&lang=EN. Nico, L. G., P. L. Fuller, and P. J. Schofield. “Ctenopharyngodon idella.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2006. http://nas.er.usgs.gov/queries/FactSheet.asp ?speciesID=514.

n Lionfish Also known as: Red lionfish, turkeyfish, devil firefish, zebrafish Scientific name: Pterois volitans/P. miles Family: Scorpaenidae (Scorpionfishes) Native Range. The Indo-Pacific Ocean region, from southern Japan to the Philippines to Micronesia and the east coast of Australia through western Polynesia to the Marquesas Island and Oeno in the Pitcairn islands. The red lionfish (P. volitans) is mostly a Pacific Ocean fish; its range extends eastward through Oceania; the devil firefish (P. miles) occurs primarily in the Indian Ocean, from Sumatra northwestward into the Red Sea. Both fishes are found off Sumatra. The devil firefish has passed through the Suez Canal into the Mediterranean Sea. Whether or not these are two true species or simply regional variants of the same species has not been conclusively determined. Genetic studies indicate that both now occur as exotic taxa in the Atlantic Ocean off the U.S. coast, but the Atlantic population consists primarily of P. volitans. Their likely source area is the Philippines. Distribution in the United States. Apparently established and reproducing from the Florida Keys to Cape Hatteras, North Carolina. Divers have reported sightings of juveniles as far north as Long Island, New York, New Jersey, and Rhode Island; but it is assumed they were carried north in the Gulf Stream as the young of the year and will either migrate south or die in winter. Winter bottom-water temperatures may create a northern limit to their distribution area as it does for other tropical fishes whose young are frequently encountered off the coast of the northeastern United States in summer. Description. Lionfish are unmistakable. The red lionfish has long, separated dorsal fin spines. The appearance of the dorsal spines together with the elaborate fan-like pectoral fins resulted in the common name, turkeyfish. The body is white to cream-colored with red-tomaroon vertical stripes that gave it another of its common names, zebrafish. The stripes have a regular, alternating pattern between wide and narrow bands and sometimes converge in a V on the sides. Fleshy tabs or tentacles occur over the eyes and above the mouth. The dorsal, anal, and pelvic spines of lionfish are highly venomous. A pair of venom glands is found on each spine, which is covered by a sheath. When a spine is pushed into flesh, the sheath presses down on the glands, and venom is released into a groove that runs along the spine, delivering the poison to the wound. The resulting sting is extremely painful, but not fatal to humans. The largest lionfish collected off the East Coast of the United States was about 17 in. (43 cm) long and weighed about 2.5 lbs. (1.1 kg). Related or Similar Species. The devil firefish and the red lionfish are very similar in appearance. They are distinguished from each other by the number of rays in the dorsal

176 n VERTEBRATES (FISH) and anal fins and by genetic assays. The lionfish usually has 11 dorsal-fin rays and 7 anal fin rays, whereas the devil firefish has 2 and 6, respectively. The two fishes are very closely related and may actually be the same species. A 2007 study showed that the composition of the Atlantic population was 97 percent lionfish and 7 percent devil firefish. Introduction History. The first known occurrence of lionfish in the Atlantic off the United States was a specimen collected near Dania, Florida, in October 1985. Later, six fish escaped into Biscayne Bay from a large private aquarium that was destroyed during Hurricane Andrew in 1992. These fish were seen alive in the bay a few days later. Sporadic or undocumented sightings of red lionfish were reported from Florida’s east coast between 1993 and 2002. In February and March 2002, three specimens were taken off northeast Florida near St. Augustine, Top: Lionfish are native to the Indo-Pacific region. Bottom: Lionfish Jacksonville, and Amelia Island. Lionfish were first recorded appear to be established along the Atlantic coast of the United States from the Florida Keys north to Cape Hatteras, North Carolina. Juveniles have off Georgia in 2001, when a sinbeen reported as far north as Rhode Island. (Adapted from Schofield, gle adult was collected. The same Morris, Langston, and Fuller 2009.) year, two juveniles were taken off Long Island, New York. Small groups of lionfish were observed during research dives in submersibles off South Carolina and North Carolina in 2002. This was the first, though circumstantial, evidence that the Atlantic population was reproducing. Although water ballast is a possible route of entry for the fish, it is highly unlikely. The red lionfish is a very popular marine aquarium species, and the aquarium trade is the most probable pathway by which the fish came to the Atlantic Ocean. The color patterns of Atlantic lionfish are quite similar to those from the Philippines, where many are collected for the aquarium trade. Either accidentally or deliberately, whether they had grown too large or for whatever reason, these (and other) aquaria pets are being dumped into the open waters of the ocean. The wild population is growing rapidly. That juvenile fish smaller than those sold for aquaria are showing up off the North Carolina coast and elsewhere is a strong indication that

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the species is reproducing. This is the first time a western Pacific fish has become established in the Atlantic Ocean off the United States. Habitat. Lionfish are tropical marine fish associated with the continental shelf biome. They inhabit reefs at depths of 30 to 575 ft. (9–175 m), where they can hide in crevices by day. Along the southeastern coast of the United States, they have been sighted on reefs and other hard substrates, including shipwrecks. In their native distribution areas, they are found in The lionfish, with its long dorsal spines and fan-like pectoral fins, is lagoons and turbid inshore unmistakable. (Albert Kok.) waters, including harbors, in addition to offshore coral reefs and rocky outcrops. Diet. Lionfish are carnivores that prey on crustaceans and small fish, including young lionfish and juveniles of some commercially important species such as grouper and snapper. They focus increasingly on fish as they age. Nocturnal hunters, lionfish move into deeper waters at night to forage. They are ambush predators and sweep up and trap their prey in their extended pectoral fins. They then quickly pounce and ingest it. Life History. Lionfish are solitary and territorial most of the year, only forming small groups during mating, when males join with several females. Males use their spines and fins in competitive visual displays. Females release a pair of mucous-encapsulated clusters of 2,000–15,000 eggs that are externally fertilized by the males. The egg mass floats, and as microbes decompose the mucous, eggs are released into the water column. Early lifehistory stages are poorly known. Presumably, lionfish larvae have a pelagic stage during which they are dispersed by ocean currents. The larval stage lasts an estimated 25–40 days. Age at sexual maturity and average lifespan are unknown. There are few known predators of lionfish, although off the Bahamas, lionfish have been found in the stomachs of native groupers. Impacts. Recent (2008) studies in the Bahamas have shown that lionfish may have negative impacts on native Atlantic reef-fishes. Reefs with lionfish had 79 percent fewer juvenile reef fish compared to reefs lacking lionfish. Prey items found in lionfish stomachs included fairy basslet (Gramma loreto), bridled cardinal fish (Apogon aurolineatus), white grunt (Haemulon plumierii), bicolor damselfish (Stegastes pertitus), several wrasses, striped parrotfish (Scarus iserti), and dusky blenny (Malacoctenus gilli). Juvenile spiny lobster (Panulirus argus) is possibly a food item. These findings suggest that lionfish affect recruitment of coral fishes and may thereby compete with native piscivores. They could potentially reduce the number of ecologically important species such as parrotfish and other herbivores that prevent macroalgae from taking over the reef. Management. Very little can be done in a marine environment to control invasive species. Environmental changes occurring on the southeastern-U.S. continental shelf favor the continued expansion of lionfish in these waters. Many important native reef fish predators have

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Tournament Held to Help Control Lionfish Population in the Florida Keys National Marine Sanctuary

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n September 2010, the Reef Environmental Education Foundation (REEF) and the Florida Keys National Marine Sanctuary sponsored a lionfish hunt with cash and other prizes for teams of divers that would catch invasive lionfish. The 27 participating teams collected a total of 534 lionfish during the weekend tournament, the winning team catching 111 in one day. The largest was 11 in. (27.9 cm) long, but most were too small to filet, so the planned follow-up feast was a failure. Nonetheless, sanctuary superintendent Sean Morton said, “The sanctuary is thrilled by the response from the dive community. The volume of fish caught during this single-day event demonstrates that dedicated diver removal efforts can be effective at helping keep this invasive [species] at bay.” Source: Frink, Stephen. “The Tipping Point(s).” Alert Diver, Fall 2010: 8.

been overfished, but even if they were at past densities, it is unknown if native predators could eventually control lionfish numbers. None of them have prior experience with a prey fish with venomous spines. The fish fauna in general has become more tropical during the last decades of the twentieth century, so it appears conditions increasingly favor the breeding and recruitment of lionfish.

Selected References Hare, J. A., and P. E. Whitfield. “An Integrated Assessment of the Introduction of Lionfish (Pterois volitans/miles Complex) to the Western Atlantic Ocean.” NOAA Technical Memorandum NOS NCCOS 2, 21 pp., 2003. http://coastalscience.noaa.gov/documents/lionfish_ia.pdf. “Invasive Lionfish Threaten Native Fish and the Environment in U.S. Atlantic Coastal Waters.” National Ocean Service, NOAA, 2009. http://oceanservice.noaa.gov/facts/lionfish.html. Masterson, J. “Pterois volitans.” Smithsonian Marine Station at Fort Pierce, 2007. http://www.sms.si.edu/ IRLSpec/Pterois_volitans.htm. Schofield, P. J., J. A. Morris Jr., J. N. Langston, and P. L. Fuller. “Pterois volitans/miles.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2009. http://nas.er.usgs.gov/queries/ FactSheet.asp?speciesID=963.

n Mosquitofish Scientific names: Gambusia affinis (western mosquitofish) Gambusia holbrooki (eastern mosquitofish) Family: Poeciliidae Native Range. The western mosquitofish is native to the south-central United States, from Illinois and Indiana south into Mexico, west to New Mexico, and east into the Mobile River drainage system. Also native in the Chattahoochee and Savanna rivers. Apparently, most introductions to other states (and worldwide) stem from a few populations from Georgia, Illinois, Tennessee, and Texas. The eastern mosquitofish is native to the Atlantic and Gulf coast drainages from southern New Jersey south and west to southern Alabama.

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Distribution in the United States. The western mosquitofish has been widely introduced into most western states. The eastern mosquitofish has likely been transplanted outside its native range only in eastern states. It is known to have been introduced into New Jersey and Tennessee as well as Alabama. Sometimes they were moved to other regions within the same state to which they are native. Such is the case in Virginia, for example. The two mosquitofish species are so similar in appearance and so closely related, and early records often so imprecise, that it is difficult to always be sure which species was transplanted where. Description. These two little fishes are very similar in appearance. They have arched backs and deep bellies. The head is large, its upper surface flattened. The eyes are very large relative to body size. The small mouth is upturned and protrusible to allow feeding from the surface. Dorsal and anal fins are rounded; small black spots appear Top: The western mosquitofish is native to water bodies in the south on the dorsal fin. The western central United States. Bottom: Gambusia affinis has been introduced into mosquitofish usually has six dor- most western states. (Both maps adapted from Nico, Fuller, and Jacobs sal rays, and the eastern mos- 2009.) quitofish seven. The head and much of the body are covered with large scales outlined by dark pigments to give a characteristic diamond pattern on the body. The back is greenish or brown, the sides gray-blue, and the belly silvery-white. In mature females, a black patch appears on the rear of the abdomen above and forward of the vent. Anal, pelvic, and pectoral fins are a pale, translucent amber. Mosquitofish are sexually dimorphic; the females are much larger than the males. Adult females may be as much as 2–2.75 in. (6–7 cm) long, adult males only about 1.5 in. (4 cm). Adult males possess a gonopodium, a long tube-like structure composed of fused rays of the anal fin and used to transfer sperm into the vent of females during mating. The gonopodium is usually held back along the belly, but during mating, it is turned down and forward. Related or Similar Species. The two mosquitofish are easily confused with each other. In Arizona, the Sonoran topminnow (Poeciliopsis occidentalis) could be mistaken for a

180 n VERTEBRATES (FISH) mosquitofish. The gonopodia of the two are distinct, that of the topminnow is asymmetrical to the left, and that of the mosquitofish is symmetrical. In addition, the pelvic fins of male Gambusia are modified with a fleshy appendage. In Florida, the sailfin molly (Poecilia latipinna) looks superficially like a mosquitofish, but lacks the net-like scale pattern, and the position of the dorsal fin differs. Introduction History. The first known introduction of mosquitofish in the United States occurred in the early 1890s. The western mosquitofish was taken from Texas to Hawai’i to test their effectiveness in consuming mosquito larvae in 1905. The same year, eastern mosquitofish from North Carolina were released into New Jersey waters to control mosquitoes. For several decades afterward, mosquitofish were routinely and widely introduced by government agencies; for example, the former U.S. Public Health Top: The eastern mosquitofish is native to drainages of the Atlantic Slope Service introduced it as a costsouth of New Jersey and of the Gulf of Mexico. Bottom: Gambusia holbrooki effective way to combat malaria. has probably been transplanted only into bodies of water in the eastern Gambusia continue to be proUnited States. (Both maps adapted from Nico and Fuller 2009.) moted and intentionally stocked by local, state, and federal agencies for mosquito control and are viewed as attractive alternatives to the use of chemical insecticides. In some areas, range expansions have occurred once introduced populations became established. Habitat. Mosquitofish can be found in slow-moving streams, ponds, and wetlands and in all sorts of artificial habitats. They thrive in shallow, often stagnant, ponds and at the edges of streams and lakes where vegetation is dense and the water shallow and warm. They will also live in slightly brackish backwaters. Mosquitofish tend to be much more tolerant of polluted water than many native fishes because they can survive at low oxygen levels. Generally subtropical to warm-temperate in distribution, they do not tolerate extremely cold temperatures, which may limit their success in northern states. Diet. Best described as omnivores, mosquitofish prefer taking zooplankters and small aquatic invertebrates near the water surface. They also consume small fish, fish eggs, and

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the larvae of amphibians. When preferred items are in short supply, they consume diatoms and other algae. Although their name implies they are proficient feeders of mosquito larvae, they seem to be no more effective in mosquito control than some native fish. Indeed, in a laboratory experiment, mosquitofish The two species of mosquitofish are very similar in appearance. Their small, protrusible mouths are upturned so they can feed at the surface fared poorly on a diet of mosof the water. (Gualtiero Boffi/Shutterstock.) quito larvae. Life History. Mosquitofish are ovoviviparous, undergoing internal fertilization of the eggs, which hatch in the mother’s body. Thus, they are livebearers and reproduce rapidly. Females can be sexually mature at six weeks of age, males at four weeks. When mating, the male swings its gonopodium forward and inserts it into the female’s vent to transfer sperm. The female is able to store sperm for several months and fertilize several broods from one copulation. Gestation lasts 3–4 weeks. When the young are born, they are little more than 0.25 in. (6 mm) long. Females can produce 4–5 broods a year, with 1–300 young in each. At birth, the sex ratio is 1:1, but in the adult population, there are fewer males than females. The typical lifespan is 15 months. Impacts. Outside their native range, mosquitofish are notoriously destructive, contributing to population declines among native fishes and amphibians. Adults are very aggressive and attack other fish, shredding their fins and sometimes killing them. They compete with or displace indigenous fishes. They also alter zooplankton communities, as well as insect and crustacean communities, by their selective predation on members of each. In some circumstances, they may actually benefit mosquitoes by eating predatory invertebrates. Mosquitofish have had especially deleterious effects in western states, where they are implicated in the elimination or decline of endemic and federally endangered and threatened fish. They have displaced the plains topminnow (Fundulus sciadicus) from preferred habitat in shallow clear streams. They have caused the threatened Railroad Valley springfish (Crenichthys baileyi) to shift its habitat and decline in numbers in springs in Nevada. In Arizona, they are responsible for the local extirpation of the endangered Sonoran topminnow (Poeciliopsis occidentalis). Populations of the Gila topminnow (P. o. occidentalis) only survive where Gambusia is absent. Another subspecies, the Yaqui topminnow (P. o. sonriensis), is threatened with a similar fate. Mosquitofish are also responsible for the demise of the least chub (Itichthys phlegethontis) in parts of Utah. Desert pupfish (Cyprinodon spp.) populations are threatened by the introduction of mosquitofish in Nevada springs. Mosquitofish are at least partially responsible for population declines in the Chiricahuan leopard frog (Rana chiricahuensis) in southeastern Arizona, in the California newt (Taricha torosa) in California, and in native damselflies on O’ahu, Hawai’i. Mosquitofish have posed problems for native species wherever in the world they have been introduced. This fish is on the IUCN’s list of “100 of the World’s Worst Invasive Alien Species.” Management. It may be possible to eradicate some populations of mosquitofish. More likely to be successful are efforts to prevent the further spread of the species. Application of rotenone to waters can be a means of eliminating mosquitofish from small areas of permanent water. The poison deprives the fish of oxygen, so they come to the surface for air and can be mechanically removed. Rotenone is a broad-spectrum piscicide, so nontarget species

182 n VERTEBRATES (FISH) are also affected. Barrier construction is feasible in some areas to stop range expansion. Regulations to halt the transport and stocking of all nonnative fishes need to be drafted or enforced to prevent future introductions.

Selected References Aarn, and Peter Unmack. “Gambusia control homepage.” 1998. http://www.gambusia.net/. IUCN/SSC Invasive Species Specialist Group (ISSG). “Gambusia affinis (Fish).” ISSG Global Invasive Species Database, 2006. http://www.issg.org/database/species/ecology.asp?fr=1&si=126. Masterson, J. “Gambusia affinis. Mosquitofish.” Smithsonian Marine Station at Fort Pierce, 2008. http:// www.sms.si.edu/IRLSpec/Gambusia_affinis.htm. Myers, G. S. “Gambusia, the fish destroyer,” Oecologia 141: 713–21, 1965. Appendix A-73. Available online at http://wildlife.utah.gov/pdf/AIS_plans_2010/AIS_12oWesternMosquitofish-Jenny -final.pdf. NatureServe. “Gambusia affinis (Baird and Girard, 1853): Western Mosquitofish.” NatureServe Explorer: An Online Encyclopedia of Life, Version 7.1, 2009. NatureServe, Arlington, VA. http:// natureserve.org/explorer. Nico, Leo, and Pam Fuller. “Gambusia holbrooki.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2009. http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=849. Nico, Leo, Pam Fuller, and Greg Jacobs. “Gambusia affinis.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2009. http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=846.

n Northern Snakehead Scientific name: Channa argus Synonym: Ophicephaslus argus Family: Channidae (Snakeheads) Native Range. China (Amur, Hwang, and Yangtze river systems), North Korea, and Russia (Amur River drainage system) Distribution in the United States. Established in Maryland (Lower and Middle Potomac River and tributaries), New York (Meadow Lake, in Queens), Pennsylvania (Edgewood Lake, Philadelphia), and Virginia (Fairfax County in tributaries of the Middle Potomac River such as Dogue Creek, Kanes Creek, Little Hunting Creek, Massey Creek, Occoquan River; also Mulligan Pond and in Pohick Bay, Fort Belvoir; Dyke Marsh, Alexandria to Mason Neck National Wildlife Refuge; King George County in Upper Machodoc Creek). It has been collected in California, Florida, Massachusetts, and North Carolina, but is not established in these states. A 2008 capture in Arkansas suggests snakeheads may be established there. Description. The northern snakehead has an elongated body with a long dorsal fin running almost the full length of the back and a long anal fin as well. The pelvic fins are close to the gills and set almost directly below the pectoral fins. The body is a golden tan with large dark irregular blotches on the flanks. The head is flattened and bears large scales resembling those of a snake. The eyes are set forward on the head, and nostrils are tubular. The mouth is large; the lower jaw is toothed and protrudes beyond the upper jaw; the roof of the mouth (i.e., palatine and prevomer bones) is also toothed. Some teeth look like the canines of mammals. Total length can reach about 40 in. (102 cm); adults may weight up to 15 lbs. (6.8 kg). Related or Similar Species. Native bowfin (Amia calva) and burbot (Lota lota), both of which have long bodies and long dorsal fins, might be mistaken for snakeheads. Bowfin

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are distinguished by a short anal fin, pelvic fins set well behind the gills and pectoral fins, and a rounded tail. A black spot appears at the base of the tail in males and juveniles. Barbots display a split dorsal fin (a shorter segment lies in front of a longer one); and a single barbel or whisker hanging below the lower jaw. Other species superficially resembling snakeheads include the American eel (Anguilla rostrata) and the sea lamprey (Petromyzon marinus). Eels lack pelvic fins and their dorsal and anal fins converge with the caudal fin so that it looks like they have a single continuous fin. Sea lampreys have a round mouth and reddish eyes (see Fish, Sea Lamprey). Introduction History. The snakehead is a popular fish in Asian food markets. Most introductions were probably deliberate efforts to raise the fish in local waters. The northern snakehead is not part of the aquarium trade, although other species in the family are. The first report of the species in the Top: The northern snakehead is native to parts of China, North Korea, United States was in 1977. and the Amur River system in Russia. Bottom: Northern snakehead This represented a failed populations are established in Maryland and Virginia. The fish has been attempt to establish a popula- collected in other states, but with the possible exception of Arkansas, tion in Silverwood Lake, San does not seem to have established populations in those areas. (Adapted Bernadino County, California. from Fuller and Benson 2009.) In 2000, three specimens were taken from the St. Johns River in Florida. Subsquent collections were made in Burnham Harbor (Lake Michigan), Chicago, Illinois; two locations in Massachusetts (2001 and 2004); Lake Wylie and South Fork Catawba River, North Carolina; and FDR Pond, Philadelphia, Pennsylvania. In June 2008, a snakehead was taken from the Schuylkill River in Philadelphia. None of these captures have been interpreted as evidence of established populations. Discovery of snakeheads in a pond in Crofton, Maryland, in June 2002 created intense media coverage and brought the problem of invasive fishes to the public’s attention. This population was subsequently eradicated by state biologists, who applied the pesticide rotenone to the water.

184 n VERTEBRATES (FISH) In April 2004, several snakeheads were collected from the Potomac River in Maryland and Virginia. The source of these fish is unknown. Many others have since been collected in the Middle and Lower Potomac River basin around Dogue Northern snakehead. The large scales on the head give this fish a snake- and Little Hunting Creeks in like appearance. (U.S. Geological Survey Archive, U.S. Geological Survey, Virginia and from the Anacostia Bugwood.org.) River in Maryland. Habitat. The northern snakehead is a purely freshwater fish; it prefers shallow ponds and sluggish streams with well-vegetated or muddy bottoms. It has also been found in wetlands. Snakeheads inhabit waters with temperatures ranging from 32°F to 86°F (0–30°C). Snakeheads are air breathers and, if kept moist, can survive out of water for as long as four days. This enables them to wriggle across land and disperse to other bodies of water. It also allows them to live in oxygen-depleted water, since they can gulp air at the surface. Diet. Snakeheads are top-level carnivores. Juveniles consume zooplankters, insect larvae, small crustaceans, and the fry of other fish species. Adults prey primarily on other fish, but will take crustaceans, frogs, small reptiles, and even small birds and mammals. Life History. These fish reach sexual maturity at 2–3 years, when they are about 12–14 in. (30–36 cm) long. Spawning occurs 1–5 times a year. A breeding pair forms a nest by making a circular clearing in aquatic vegetation, sometimes weaving the plants they removed around the edge to protect a vertical column of water. The female releases 1,300 to 15,000 eggs near the center of the water column. The male wraps his body around hers as he releases milt and fertilizes the eggs when she releases them. Each egg contains a droplet of oil that lets it float. The snakehead pair, which remain together throughout the spawning season, guard the eggs and then the fry when they hatch 28–48 hours later. The fry remain in the nest until they are about 0.3 in. (8 mm) long, at which time the yolk sac is completely absorbed. Typically, the young stay together in a pack guarded by an adult until they reach early juvenile stage; they are then about 0.7 in. (18 mm) long and beginning to eat zooplankton. Impacts. Unknown. As predators, they are expected to compete with native fishes for food and habitat. Management. It is difficult to impossible to eradicate a population from a river system. Snakeheads can be removed from ponds by applying rotenone, but nontarget fish are killed too. Preventing new introductions is the main management strategy. Since 2002, federal law prohibits the introduction and interstate transport of live snakeheads or their eggs without a permit in the United States, the Commonwealth of Puerto Rico, or any territory or possession of the United States.

Selected References “Do You Know the Difference?” Virginia Department of Game and Inland Fisheries, 2004. http:// www.dgif.state.va.us/fishing/snakehead_comparisons_052004.pdf. Fuller, P. F., and A. J. Benson. “Channa argus (Cantor 1842).” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2009. http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=2265. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Channa argus (fish).” ISSG Global Invasive Species Database, 2005. http://www.issg.org/ database/species/ecology.asp?si=380&fr=1&sts.

RAINBOW TROUT n 185 “Recognizing Northern Snakehead.” U.S. Fish and Wildlife Service, 2003. http://www.ans taskforce.gov/Education/Snake head_Final%20from%20RO.pdf. U.S. Fish and Wildlife Service. “Injurious Wildlife Species: Snakeheads (Family Chanidae): Final Rule.” Federal Register 67 (193), Rules and Regulations: 62193–62204, October 4, 2002.

n Rainbow Trout Also known as: Steelhead (anadromous form) Scientific name: Oncorhynchus mykiss Synonyms: Salmo gairdnerii, Fario gairdnereri Family: Salmonidae Native Range. North America. Pacific slope streams from the Kuskokwim River, Alaska, south to Rio Santa Domingo, Baja California, Mexico. Also in the upper Mackenzie River drainage system, Alberta and British Columbia, Canada; and in internal drainages of southern Oregon. Distribution in the United Top: Rainbow trout are native to Pacific Slope streams in North America. States. Rainbow trout has been Bottom: Rainbow trout have been transplanted into streams in all 50 stocked in all states. states and Puerto Rico. (Both maps adapted from Fuller 2009.) Description. Rainbow trout are deep-bodied, compressed fishes with large heads; mouths extend to the back of the eyes. Coloration is highly variable. (There are hundreds of varieties and several subspecies of native rainbow trout.) The back is bluish to dark olive-green. Black spots appear on the back and may extend down the sides as far as the lateral line. Radiating rows of black spots appear on the unforked tail. The sides are silver, and the belly and underside of head are white. Often a pink or reddish band runs along the sides of the body and head. Colors become much more intense when rainbows are on spawning runs. Resident riverine populations normally exhibit the most intense pink stripe and heaviest spotting. Rainbows can be positively identified by the 8–12 rays in the anal fins and lack of teeth at the base of the tongue. A typical four-year-old river rainbow weighs about 1 lb. (0.5 kg) and is about 13 in. (33 cm) long. Lake-dwelling rainbow trout will be larger. Related or Similar Species. Brown trout (see Fish, Brown Trout).

186 n VERTEBRATES (FISH) Introduction History. Stocking of this fish outside its native range began in the late 1800s. Introductions have been primarily into streams for sportfishing. Around the world, rainbow trout are one of the most widely introduced fish species and important in aquaculture, as they are highly valued food fish. Habitat. Rainbow trout is usually a freshwater species, although anadromous populations occur where rivers are Coloration on rainbow trout is highly variable. Usually a reddish band open to the sea. Such fishes are runs along the sides of the head and body. (Eric Engbretson.) called steelheads or coastal rainbows. Rainbows thrive in cool, clean, well-oxygenated streams and lakes where temperatures range from 50°F (10°C) to 75°F (24°C). A water temperature around 54°F (12°C) is preferred. Diet. Rainbow trout consume zooplankters, crustaceans, larval and adult insects both aquatic and terrestrial, mollusks, fish eggs, and small fishes. Young trout feed on zooplankters. Life History. Rainbow trout usually migrate into small tributary streams of lakes to spawn in the spring. The female uses her tail to excavate a redd or depression 4–12 in. deep and 10–15 in. (25–38 cm) in diameter in the streambed gravel into which she releases 700– 4,000 orange-red eggs. The male then fertilizes the eggs. The female covers successive groups of fertilized eggs by digging at the upstream edge of the redd. When spawning is finished, the redd consists of layers of eggs and clean gravel, and the adults leave. Depending on water temperature, eggs incubate for 1–5 months. Several weeks after hatching, the fry wriggle through the gravel and swim free. They shelter and feed along the edges of streams or near lake shores for 2–3 years. In native populations, sexual maturity is usually reached at age 6–7. Most introduced populations are bred in hatcheries and released into local streams just ahead of the fishing season. Fishing pressures typically deplete the population, so they must be restocked each year. They may also be restocked annually in areas where environmental conditions are not conducive to self-sustaining populations. Impacts. A major problem with the introduction of rainbow trout outside their native range has been their ability to hybridize with other native salmonids. They thereby threaten the genetic integrity of several rare species and subspecies vulnerable to extinction. In California, they have crossed with Lahontan cutthroat trout (O. clarki henshawi), redband trout (O. mykiss subspp.), and California golden trout (O. mykiss aguabonita), the state fish. In the Lahontan drainage east of the Sierra Nevada and in several Rocky Mountain rivers, hybridization with rainbow trout has been a major cause of the decline of native cutthroat trout. In Nevada, it is implicated in the extinction of the Alvord cutthroat (O. clarki alvordensis), and in Arizona, it hybridizes with native Gila trout (O. gilae) and Arizona trout (O. gilae apache). Rainbow trout negatively affect other species through predation and aggressive behavior. For example, rainbows push the Little Colorado spinedace (Lepidomeda vittata) from the

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undercut banks where it seeks shelter into open water, where it becomes much more vulnerable to predation. They are also known to drive suckers and squawfish off their feeding territories. In the Little Colorado River, rainbow trout prey upon endangered humpback chubs (Gila cypha). They are at least partly responsible for declines in the Chiricahuan leopard frog (Rana chiricahuensis) in southeastern Arizona and the Sierra Nevada yellow-legged frog (R. sierrae). They also compete with native brook trout (Salvelinus fontinalis) in many locations. Through the stocking of hatchery-bred rainbows in rivers in more than 20 states, whirling disease has been introduced into open waters, where it threatens native species. Whirling disease is caused by a parasite (Myxobolus cerebralis) of salmonids. Introduced from Eurasia, the cnidarians-like organism infects juveniles and affects the nervous and skeletal systems, resulting in a curvature of the spine that affects the victim’s ability to maintain its orientation in the stream. Infected fish swim in spirals, chasing their tails. Mortality rates are very high. Rainbow trout has been nominated as one of “100 of the World’s Worst Invasive Alien Species” by the IUCN/SSC Invasive Species Speciality group. Management. Most management practices favor rainbow trout since they are an important element in sport fisheries across the country. Many continue to be raised in hatcheries and used in put-and-take operations.

Selected References Fuller, Pam. “Oncorhynchus mykiss.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2009. http://nas.er.usgs.gov/queries/factsheet.asp?SpeciesID=910. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSC). “Oncorhynchus mykiss (fish).” ISSC Global Invasive Species Database, 2006. http:// www.issg.org/database/species/ecology.asp?fr=1&si=103. Root, Laurie. “Rainbow Trout (Oncorhynchus mykiss).” South Dakota Department of Game, Fish & Parks, 1994 http://www3.northern.edu/natsource/FISH/Rainbo1.htm. “Steelhead /Rainbow Trout” Alaska Department of Fish and Game, 2011. http://www.adfg.alaska.gov/ index.cfm?adfg=steelhead.main. Talbot, Ret. “Native California Trout Species and Subspecies: At Risk Rainbow and Cutthroat Trout Indigenous to California.” Suite 01.com. 2009. http://freshwater-fish.suite101.com/article.cfm/ native_california_trout_species_and_subspecies.

n Round Goby Scientific name: Neogobius melanostomus Synonym: Apollonia melanostomus Family: Gobiidae Native Range. Eurasia. Native to brackish waters of the Sea of Azov, Black Sea, and Caspian Sea and their tributary streams, where it prefers brackish waters. Distribution in the United States. Great Lakes and their tributary streams and connecting canals. Description. The round goby is a small, soft-bodied fish with eyes raised above its head as in frogs. Its lips are thick. Body color is a mottled gray, brown, or greenish color, except in breeding males, which are black. The front dorsal fin usually has a conspicuous black spot. Pelvic fins are fused to form a suction disk. The front dorsal fin has 5–6 spines, and the posterior dorsal fin has one spine and 13–16 soft rays. The anal fin has one spine and 11–14 soft rays. Adult gobies are 4–10 in. (10–25 cm) long. In the Great Lakes, they rarely grow larger than 7 in. (18 cm).

188 n VERTEBRATES (FISH) Related or Similar Species. Round gobies are similar in appearance to native sculpins (Cottus spp.), which have two separate pelvic fins instead of the fused one of gobies. They also look similar to tubenose gobies (Proterorhinus marmoratus), another exotic fish in the Great Lakes. The tubenose goby has nostrils that extend forward in tubes to or beyond the lower lip. There is no spot on the front dorsal fin, but oblique black lines. It usually is only about 4.5 in. (11 cm) long. Smaller and less aggressive than round gobies, the tubenose has only been found in Lake St. Clair, the St. Clair River, the Detroit River, and western Lake Ontario, although recently it appears to be spreading in Lake Erie. Introduction History. The round goby was first collected in the United States in 1990 from Lake St. Clair. They most likely were introduced during ballast water exchange by transAtlantic ships coming from Top: The round goby is native to fresh and brackish waters of the Sea of the Black Sea region. By 1993, Azov, Black Sea, and Caspian Sea, as well as their tributaries. (Adapted it had entered Lake Erie. In from Stepien, Carol, Joshua Brow, and Emily Sopkovich. “Round Goby 1994, it appeared in Lake Phylogeography,” Lake Erie Center, University of Toledo, 2009. http:// Michigan near Chicago. It has www.utoledo.edu/as/lec/goby/RoundPhy.html.) Bottom: Round gobies since been collected near the are invasive in all of the Great Lakes and many of their tributary terminus of the Chicago Sanistreams. (Adapted from Fuller, Benson, and Maynard 2009.) tary and Shipping Canal, entryway to the Mississippi River drainage system. In 1995, gobies were collected from Wisconsin waters in Lake Superior and, in 1996, from Duluth Harbor, Minnesota. The spread to Lake Superior was probably aided by freighters operating on the lakes. By 1998, the round goby was reported from several Michigan sites on Lake Huron. Gobies were reported in the Erie Canal, Buffalo River, St. Lawrence River, Genessee River, Tonowanda Creek, and Lake Ontario in 2004 and 2005. Today there are large populations in Lakes Erie, Ontario, and St. Clair. Lake Michigan experienced a population explosion of gobies in 2008. Habitat. Freshwater lakes, streams, and canals. These bottom-dwelling fish prefer hard substrates such as rock, gravel, or sand and areas shallow enough for aquatic macrophytes

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to grow. They hide in crevices. They tolerate a wide range of temperatures and are able to inhabit brackish water and degraded water quality. Diet. Round gobies are carnivores and feed on zooplankters, mollusks, aquatic insects and benthic invertebrates, fish eggs, and small fish. They feed voraciously on zebra mussels (Dreissena polymorpha), another invasive species in the Great Lakes (see Mollusks, Zebra Mussel). Gobies are able to pluck mussels from their The round goby’s pelvic fins are fused to form a suction disk. In their attachment sites on the lake introduced range, they are rarely more than 7 in. long. (Eric Engbretson.) floor and crush them with their pharyngeal teeth. They spit out the shells before swallowing the soft insides. Gobies have well-developed lateral lines, which increase their ability to detect water movement and allow them to be nocturnal feeders. Life History. Gobies spawn from April to September. Males migrate from wintering sites in deeper water to spawning areas ahead of the females. They establish territories and attract mates by releasing pheromones. Females attach 500–3,000 eggs to the underside of rocks, in pipes, or on other sheltered hard surfaces. They utilize several nests and spawn with several different males. Males aggressively guard the nests and newly hatched young. Gobies will spawn every 20 days during the long season. Females are sexually mature at 1–2 years; males at 3–4 years. Males die after spawning, so population sex ratios are usually skewed to favor females. Impacts. Round gobies compete with native fishes for food and space and could potentially have serious impacts on aquatic ecosystems if they were to gain entry to the Mississippi drainage system. Their ability to feed at night and their ability to cling with their pelvic fins to rocks in fast currents give them a competitive advantage over native species, many of which have overlapping food preferences. They compete for small macroinvertebrates with rainbow darters (Etheostoma caeruleum), logperch (Percina caprodes), and northern madtoms (Noturus stigmosus). Since gobies were introduced to Lake St. Clair, populations of native sculpin and logperch have declined. They are known to eat the eggs and fry of lake trout and the eggs of lake sturgeon, and to prey on small darters in laboratory situations. Since adult round gobies vigorously defend their spawning territories, they become dominant in prime spawning areas and displace natives. Mottled sculpin (Cottus bairdi) is one species that has been affected in that way by the establishment of round gobies. Large, mature gobies drive them from spawning sites; and small gobies, focusing on insects, compete with them for food. Indirectly, gobies have had an impact on smallmouth bass (Micropterus dolomieu) in Lake Erie. Male bass guard nests and can successfully ward off goby attacks. However, if the males are removed through fishing, gobies immediately move in and gorge themselves on bass eggs. In order to preserve the smallmouth bass population, the State of Ohio has had to close

190 n VERTEBRATES (FISH) the fishery in May and June, while bass are spawning. This has led to a significant economic loss as anglers traditionally took half the bass catch during those months. Gobies also affect recreational fisherman by snatching the bait from their hooks. On the positive side, the diet of large adult round gobies overwhelmingly consists of zebra mussels. No other fish in the Great Lakes exploits this resource to such an extent. However, predation of zebra mussels by gobies is not sufficient to stem the spread of those aquatic invaders. And because zebra mussels are filter-feeders and accumulate contaminants in their body tissues, fish that eat gobies will biomagnify the concentrations, potentially rendering some sportfishes unfit for human consumption. Some native fishes, including smallmouth bass and walleye, consume gobies. It is hoped that Atlantic salmon (Salmo salar), introduced into the Great Lakes in 1966 to feed on alewives (see Fish, Alewife), may switch to gobies as alewife populations decline in Lake Michigan, threatening the salmon fishery. Management. Controlling or reducing the goby populations of the Great Lakes is impossible. Preventing the inland spread of the invader is the key goal of management. Electric barriers on tributary streams are under consideration. Good fishing and boating practices need to be applied and enforced. Dumping of ballast water in waterways needs to be regulated. Live bait should not be discarded into water. Boats, trailers, and fishing gear should be thoroughly inspected upon leaving any body of water and all visible organic debris removed. All water should be drained from the boat before leaving the shoreline. All boats should be washed and then sun-dried for five days before being put into another body of water.

Selected References Crosier, Dani, and Dan Malloy. “Round goby (Neogobius melanostomus),” United States Federal Aquatic Nuisance Species Task Force, 2005. http://www.anstaskforce.gov/spoc/round_goby.php. Fuller, P., A. Benson, and E. Maynard. “Neogobius melanostomus.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2011. http://nas.er.usgs.gov/queries/FactSheet.asp ?speciesID=713. Hayes, R. “Neogobius melanostomus.” Animal Diversity Web, University of Michigan Museum of Zoology, 2008. http://animaldiversity.ummz.umich.edu/site/accounts/information/Neogobius _melanostomus. Morlock, Jerry W. “Invasive Species Round Goby Has Population Explosion in Lake Michigan.” Michigan Live LLC, 2009. http://www.mlive.com/news/muskegon/index.ssf/2009/01/invasive _species_round_goby_ha.html. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Neogobius melanostomus (Fish).” ISSG Global Invasive Species Database, 2006. http:// www.issg.org/database/species/ecology.asp?si=657&fr=1&sts. “Round Goby.” Great Lakes Science Center, USGS, 2008. http://www.glsc.usgs.gov/main.php ?content=research_invasive_goby&title=Invasive%20Fish0&menu=research_invasive_fish.

n Sea Lamprey Also known as: Lamprey eel, lake lamprey Scientific name: Petromyzon marinus Family: Petromyzontidae Native Range. The Atlantic coast of North America from Labrador to Florida and into the Gulf of Mexico. This is primarily a marine fish, but it ascends freshwater rivers to spawn. It is native to Atlantic Slope drainages, the St. Lawrence River, and probably Lake Ontario, and it is

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probably also native in the Finger Lakes of New York, and Lake Champlain, New York/Vermont. It also occurs naturally along the Atlantic coast of Europe and in the western Mediterranean Sea. Distribution in the United States. Sea lampreys are nonnative transplants established and invasive in the four upper Great Lakes and in cold, clear streams in the region. Currently, populations are especially high in the St. Mary’s River, which connects Lake Huron and Lake Michigan. Description. The sea lamprey is a thin, eel-like fish without jaws. A member of a primitive group of agnathans, its skeleton is made of cartilage. The body is smooth and scaleless. It has two close dorsal fins situated toward the rear of the body, but no paired fins, no lateral line, and no swim bladder. There are seven gill slits. The back is gray-blue, with a metallic violet shimmer on the often mottled sides. The belly is yellow to silver-white. The seven gill openings are lined up behind the eyes, which are Top: The native range of the catadromous sea lamprey encompasses the red. The mouth is a disk-like Atlantic coasts of North America and Europe. It is probably also native sucker containing whorls of 100 to Lake Ontario, the Finger Lakes of New York, and Lake Champlain. or more sharp, curved teeth Bottom: The sea lamprey is invasive in Lakes Superior, Huron, made of keratin and a toothed Michigan, and Erie and in their clear, cold tributary streams (Both maps adapted from Fuller, Nico, and Maynard, 2009.) “tongue.” Total length of adults ranges between 12 and 20 in. (30.5–50.8 cm); landlocked fish are usually smaller than native marine-dwelling individuals, which may attain lengths of 24–30 in. (61–76 cm). Adults weigh 8–13 oz. (0. 23 kg). Related or Similar Species. There are four other native species of lamprey in the United States: the silver lamprey (Ichthyomyzon unicuspis), chestnut lamprey (Ichthyomyzon castaneus), northern brook lamprey (Ichthyomyzon fossor), and American brook lamprey (Lampetra appendix). The latter two, unlike the sea lamprey, are not parasitic. All are benign. Each has a characteristic structure to its mouth and arrangement of the teeth, which differ from that of the sea lamprey and are diagnostic. American eels (Anguilla rostrata), true eels, might be mistaken for sea lampreys, but they have jaws and a sharp, pointed head.

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A. The sea lamprey is a jawless fish that resembles an eel. (Andrei Nekrassov/Shutterstock.) B. The mouth of the sea lamprey is a sucker containing whorls of sharp teeth and a toothed “tongue.” (U.S. Environmental Protection Agency, Great Lakes National Program office.)

Introduction History. Sea lampreys were first reported in Lake Ontario in 1835. It was not collected from Lake Erie until 1921. It was found in Lake Michigan in 1936, Lake Huron in 1937, and Lake Superior in 1946. Increasingly, genetic evidence points to the sea lamprey being native to Lake Ontario and, along with populations in Lake Champlain and the Finger Lakes, a relict of the last Pleistocene glaciation. Niagara Falls presented a barrier to dispersal from Lake Ontario into Lake Erie until the Welland Canal was opened in 1829 to bypass the falls. Still, it seems lampreys were not able to overcome the barrier until improvements were made on the canal and lock system in 1919. Within two years, it was in Lake Erie and within 25 years, it had spread to all the other Great Lakes. Habitat. The larvae inhabit soft sediments at the bottoms of clear streams. Adults are parasitic and attach to larger fish in temperate cool-water lakes. They tolerate temperatures ranging from 40°F (5°C) to 68°F (20°C). Diet. Larvae are filter-feeders, consuming invertebrates and detritus from the water. Juveniles are external parasites on healthy fish. A sea lamprey fastens onto its victim and uses its tongue to rasp a hole in the host fish’s body. It then sucks out the blood, body fluids, and flesh, keeping the wound open for hours or even weeks by means of an anticoagulant in its saliva. One lamprey is estimated to eat 40 lbs. of fish in its lifetime. Mature adults do not feed. Life History. In their native habitat, sea lampreys spawn in freshwater streams where the substrate is stony. They move upriver in late May and early June, by which time the adults are no longer feeding. The male and female excavate nests, or redds, about 6 in. (15 cm) deep and 2–3 ft. (60–90 cm) in diameter, removing stones with their sucker mouths, and piling them downstream. Both attach themselves to a large stone at the upstream edge of the nest. (This behavior is reflected in their Latin name: petromyzon means “stone sucker.”) With the male wrapped around the female, the pair stirs up sand and deposits eggs and milt. The sand grains stick to the fertilized eggs, burying them; the larvae develop in the stream bottom. Adults die after spawning.

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The larval (ammocoete) stage lasts 6–8 years. When 4–5 in. long, the larvae undergo an extreme metamorphosis and transform into adults. It is then that they migrate downstream into estuaries and the sea, where they remain as parasitic juveniles for 1–2.5 years. Populations introduced into the Great Lakes or that may be landlocked, ice age relicts in the Finger Lakes and Lake Champlain, of course, never go to sea; instead, juveniles migrate from the streams where they hatched and spend their long larval period in freshwater lakes, where they attach themselves to large lake fish, including lake trout (Salvelinus namaycush), yellow perch (Perca flavescens), burbot (Lota lota), walleye (Stizostedion vitreum), channel catfish (Ictalurus punctatus), and northern pike (Esox lucius). At the end of the juvenile period, they become sexually mature adults, cease feeding, and swim upriver to spawn. Impacts. The introduced sea lamprey is considered to have been a major factor in the collapses of lake trout, whitefish (Coregonus clupeaformis), and chub (deepwater ciscos) fisheries in the Great Lakes (especially in Lakes Huron and Michigan and eastern Lake Superior) during the 1940s and 1950s. In its parasitic phase, its attacks and feeding on other fish result in high mortality among host species. It kills directly by sucking out fluids and tissues, and it kills indirectly by leaving open wounds vulnerable to infection. Circular scars on surviving host fish attest to many of them having been attacked more than once. The species’ introduction to the Great Lakes coincided with major declines in several large native fish that had been important in commercial fisheries and sport fisheries. Combined with the effects of pollution and overfishing, the influx of sea lampreys led to the extinction of three endemic fish: the longjaw cisco (Coregonus alpenae), deepwater cisco (C. johannae), and blackfin cisco (C. nigripinnis). Since lamprey had so reduced populations of predatory fish, populations of the invasive alewife (Alosa pseudoharengus) exploded and affected the species composition of the native fish fauna (see also Fish, Alewife). Although sea lamprey populations have been reduced in most parts of the Great Lakes, they are still abundant enough to hamper restoration efforts directed at native game fish and the introduced Atlantic salmon. Management. The Great Lakes Fishery Commission, U.S. Fish and Wildlife Service, and Fisheries and Oceans Canada are all involved in controlling sea lampreys in the Great Lakes. Mechanical weirs and electrical barrier were the first methods used to control the upstream migration of spawning sea lampreys. The release of sterile males also was implemented to reduce successful reproduction. In the late 1950s, an effective lampricide, TFM (trifluoromethyl-4-nitrophenol), was developed. This chemical kills lamprey larvae in the stream bottom. It was successful in reducing populations by over 90 percent and allowing the recovery of some commercial fisheries. TFM must be used repeatedly to remain effective, and sometimes it is harmful to nontarget species such as walleye and native lampreys. Recently, a controlled-release version of the lampricide Bayluscide was developed at the Upper Midwest Environmental Sciences Center (USGS); it is supposed to kill sea lamprey larvae in bottom sediments without affecting other species.

Selected References Fuller, Pam, Leo Nico, and Erynn Maynard. “Petromyzon marinus.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2009. http://nas.er.usgs.gov/queries/FactSheet.asp ?SpeciesID=836. “Sea Lamprey.” Upper Midwest Environmental Sciences Center, USGS, 2007. http://www.umesc .usgs.gov/invasive_species/sea_lamprey.html. Summers, Adam P. “Sea Lamprey, Petromyzon marinus.” Department of Biology, University of Massachuseatts, Amherst, 1997. http://www.bio.umass.edu/biology/conn.river/sealampr.html.

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n Silver Carp Also known as: Flying carp Scientific name: Hypophthalmichthys molitrix Family: Cyprinidae Native Range. Large Pacific drainages of eastern Asia. Silver carp are native to major lowland rivers from the Amur River of far-eastern Russia south to the Pearl River of China, and possibly into northern Vietnam. Distribution in the United States. Established in the Mississippi River drainage system in Illinois and Louisiana. Silver carp have been reported in Alabama, Arizona, Arkansas, Colorado, Florida, Indiana, Kansas, Kentucky, Mississippi, Missouri, Nebraska, Ohio, South Dakota, and Tennessee, but these may not be reproducing populations. Description. The silver carp is a large, deep-bodied fish with a laterally compressed body. A long ventral keel extends forward from the vent almost to the junction of the gill membranes and is diagnostic. The lateral line is complete and bends down toward the belly. Large eyes are set low on the head. The mouth is large, toothless, and downturned. There are no barbels. Gill rakers are thin, branched, and fused into a sponge-like structure. The pharyngeal teeth are in one row, four on a side, at the back of the throat and have striated surfaces. The short dorsal fin has a moderately stiff, non-serrated spine at its origin; it begins behind the origin of the pelvic fins. The anal fin is hooked and has a slightly stiffened spine at the origin. The caudal fin is forked. Pectoral fins have 15–18 rays and a stiff, hard spine with a finely serrated rear margin. Small specimens lack spines on their fins. Scales are very small on the body, and the head and operTop: Silver carp are native to the large lowland rivers of East Asia from the Amur River south to the Pearl River. Bottom: Silver carp are invasive in cules are scaleless. Juveniles are the Mississippi River system and have been reported elsewhere silvery all over. The backs and (Adapted from Nico 2009.)

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upper sides of adults turn greenish, and gradually become silvery below the lateral line. Silver carp grow to more than 3 ft. (1 m) long and may weigh 60 lbs. (27 kg) or more. Related or Similar Species. Silver carp are most similar to In silver carp, a long keel on the belly is diagnostic, as is the long lateral another Asian carp, the bighead line that bends toward the belly. (Michigan Sea Grant archives.) carp (Hypophthalmichthys nobilis). The bighead has a shorter ventral keel and irregular dark blotches over its body (see Fish, Bighead Carp, for a more detailed description). The presence of a ventral keel separates both silver and bighead carp from all native cyprinids except the golden shiner (Notemigonis crysoleucas), which has larger scales and five pharyngeal teeth on each side of its jaw rather than the four found in Asian carps. Native shad could be mistaken for small juvenile silver carp, but shad have no lateral line and fewer than 14 rays in the anal fin. Introduction History. Silver carp were first imported into the United States in 1973 by a private fish farmer in Arkansas for the purpose of controlling phytoplankton in his fish ponds. It was soon being raised at six state, federal, and private hatcheries and, by the 1970s, stocked in several municipal sewage lagoons. It was first discovered in natural waters in 1980, presumably the result of escapes from hatcheries and other facilities. Silver carp in the Ouachita River in Louisiana likely stem from escapes from an aquaculture site upstream in Arkansas. Florida received silver carp via a contaminated stocking of grass carp legally introduced to control aquatic plants. In Arizona, silver carp also came in a contaminated shipment of grass carp, but this was an illegal stocking. Ohio River fish may be products of the stocking of nearby ponds or from populations originating in Arkansas. Habitat. Silver carp is a freshwater fish that inhabits large rivers, lakes, and ponds. It needs moving water for spawning and proper development of eggs. Flooded lowlands make good nursery areas for larvae and juveniles. Diet. Adult silver carp filters phytoplankters, bacteria, and detritus from the water with its specialized gills. It reportedly also grazes aquatic plants. Juveniles feed on zooplankters. It feeds by rapidly gulping water as it swims, then closing its mouth and pumping the water out through its opercula. Those food particles taken in are ground by the pharyngeal teeth against a cartilaginous plate. Life History. Silver carp are sexually mature at three years of age. In their native range, they migrate to communal spawning areas during the spring highwater period. They spawn in small groups of 15–25 fish at dusk and at dawn, when the water temperature is between 65° and 68°F (18–20°C). They require water moving enough to aerate the eggs and let them float downstream in the current. Impacts. Silver carp is believed to have the potential to greatly alter native aquatic ecosystems because of its consumption of plankton, a food required by larval fish and native mussels. It could also compete with adults of some native fishes such as gizzard shad and bigmouth buffalo (Ictiobus cyprinella) and introduce diseases. A greater impact occurs on fishermen and recreational boaters. Silver carp swim near the surface and are easily disturbed by boat motors. When startled, they leap high out of the water, the reason they are sometimes called flying carp. Being struck by a 40–60 lb. (18–27 kg) fish hurtling through the air can cause serious injury.

196 n VERTEBRATES (FISH) Management. The U.S. Fish and Wildlife Service lists silver carp as an injurious species; and under the Lacey Act, it is illegal to import it into the United States. The fear that this fish and its close relative the bighead carp could devastate Great Lakes fisheries has led the U.S. Army Corp of Engineers and the State of Illinois to construct electric barriers in the Chicago Sanitary and Ship Canal to halt its dispersal into the lakes from the Mississippi River (see also Fish, Bighead Carp).

Selected References “Aquatic Invasive Species. Silver Carp.” Indiana Department of Natural Resources, 2005. http:// www.in.gov/dnr/files/SILVER_CARP.pdf. Nico, Leo. “Hypophthalmichthys molitrix.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2011. Revised January 11, 2011. http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=549. “Silver carp. Hypophthalmichthys molitrix.” Florida Integrated Science Center, USGS, 2005. http:// fl.biology.usgs.gov/Carp_ID/html/hypophthalmichthys_molitrix.html.

n Spotted Tilapia Also known as: Black mangrove cichlid Scientific name: Tilapia mariae Synonyms: Tilapia dubia, T. meeki Family: Cichlidae Native Range. West Africa, in coastal rainforest streams and brackish lagoons from the Tabou River in Coˆte d’Ivoire to the Pra River in Ghana and from southeast Benin to the Kribi River in Cameroon. Distribution in the United States. Established in at least eight counties of southern Florida and in a few springs in Nevada. They are present in the Salton Sea, Colorado River, and Los Angeles area of California, and possibly established in Arizona. Description. Spotted tilapia have compressed oval bodies. The two dorsal fins appear as a single fin; the forward one has 16 sharp spines and the rear one 12–13 soft rays. The tail is fan-shaped. The anal fin has three spines at the front and 10–11 rays that taper to a point at the rear. The mouth is terminal, and the large eye reddish. Coloration is distinct. Juveniles bear no spots on the body but have a disruptive pattern of black bars on a yellow-green or gold background. There is a prominent black spot on the back of the dorsal fin, however. The bars fade with age, and 6–9 irregular square dark blotches appear along the midline of the flanks of adults. Some show pink or red coloration on chin or throat when spawning. Some sexual dimorphism is present among spotted tilapia. Males have somewhat longer dorsal and caudal fins, both of which display shimmering white spots not found in females. Also, the foreheads of males have a steeper rise. Spotted tilapia are smaller than most of the many other Africa cichlids established in Florida and other Gulf states, and it is the most abundant. Florida specimens typically are between 6 and 8 in. (15–20 cm), although they may grow to 12 in. (30 cm) or more and weigh up to 3 lbs. (1.4 kg). Most fish larger than 10 in. (25 cm) are males. Related or Similar Species. Spotted tilapia resemble some native sunfishes in body and mouth shape. Occasionally, they are mistakenly called “oscars.” They are very similar to the introduced redbelly tilapia (T. zilli), but that species has been eradicated in Florida.

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Introduction History. The first known occurrence of spotted tilapia in the United States dates to April 1974, when it was discovered in Snapper Creek Canal in South Miami, Miami-Dade County. Florida. It quickly became established in canals throughout eastern Miami-Dade and southeastern Broward County. It was established in Everglades National Park and Big Cypress National Preserve by the late 1980s. These fish originated as escapes or intentional releases from aquarium fish producers in Dade County sometime between 1972 and 1974. Similarly in Nevada, introduction was related to an aquarium release. Spotted tilapia have been abundant in Rogers Spring, a thermal spring in the Lake Mead National Recreation Area, Clark County, since 1980. Habitat. Spotted tilapia prefer warm, slow-moving waters. They thrive in canals in South Florida and in warm springs in Nevada. Adults and juveniles stay close to sheltering struc- Top: Spotted tilapia are native to rainforest streams and brackish lagoons tures such as vegetated shores in West Africa. (Adapted from Robins, n.d.) Bottom: Spotted tilapia are or rock outcrops. They need invasive in Florida and also established in Arizona. They are present in hard, flat surfaces when spawn- the Colorado River and Salton Sea. (Adapted from Nico 2009.) ing. Optimal water temperatures are 77–91°F (25–33°C); temperatures below 52°F (11°C) are not tolerated. Diet. These fish feed primarily on “aufwuchs,” the attached algae, detritus, and associated small invertebrates that grow on various plant and rock surfaces. They will also filter phytoplankton from eutrophic (plankton-rich) waters. Life History. Spotted tilapia form pair bonds well before spawning begins and stay together to care for eggs and fry. Typically, breeding colonies assemble on the spawning grounds. In Florida, spawning generally occurs between November and March and may be synchronized with the lunar cycle, more batches of eggs being laid just before the full moon. These fish are substrate spawners and prefer gravel nests under flat rocks. Each female produces 200–2,000 turquoise eggs that stick to the gravel bottom. Two days after the eggs are laid, she removes all fertile eggs to a nearby pit and eats all infertile eggs. Early-stage larvae have “head glands” that produce a sticky strand by which the young attach themselves to

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A. Adult spotted tilapia. (© Noel Burkhead.) B. Juvenile spotted tilapia. (© Noel Burkhead.)

the substrate so that they will not drift away. Both parents guard and feed the hatchlings until they are free-swimming some nine days later, when they are about 1 in. (2.5 cm) long and have developed the cryptic barring typical of juveniles. Spotted tilapia are sexually mature at 7 in. (18 cm). Impacts. Spotted tilapia disperse rapidly and quickly become the dominant fish in both numbers and biomass in habitats to which they are introduced, thereby reducing biodiversity. By virtue of their numbers, they may compete with native fish for food. They may also compete with native fish such as sunfishes for spawning areas, since they aggressively defend their nests and broods. Management. In the 1980s, Florida attempted to control spotted tilapia by introducing yet another exotic fish, the predatory South America peacock cichlid (Cichla ocellaris) to feed upon it. How successful this effort was is open to question; the two species seem to have reached an equilibrium in their predator-prey relationship. Prevention of further spread of tilapia is the main goal of management. It is illegal to transport or possess live tilapia in Florida. This fish is edible, so fishermen wishing to eat tilapia should immediately kill them and put them on ice.

Selected References National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Tilapia mariae (Fish).” ISSG Global Invasive Species Database, 2009. http://www.issg.org/ database/species/ecology.asp?si=1430&fr=1&sts=&lang=EN. Nico, Leo. Tilapia mariae. USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2006. http://nas.er.usgs.gov/queries/factsheet.asp?SpeciesID=482. Robins, Robert H. “Spotted Tilapia.” Florida Museum of Natural History, n.d. http://www.flmnh .ufl.edu/fish/gallery/Descript/SpottedTilapia/SpottedTilapia.html.

n Walking Catfish Also known as: Magur Scientific name: Clarias batrachus Family: Clariidae Native Range. Southeast Asia. Native to Bangladesh, eastern India, Indonesia, Malaysia, Myanmar (Burma), Pakistan, Singapore, Sri Lanka, and Thailand. The fish introduced to Florida were from Thailand.

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Distribution in the United States. Established throughout most of Florida, including Everglades National Park, Big Cypress National Preserve, Florida Panther National Wildlife Refuge, and Pelican Island National Wildlife Refuge. Reported from California, Connecticut, Georgia, Massachusetts, and Nevada. Description. The walking catfish has a flat, broad head and an elongated body tapering toward the tail. It has a typical catfish appearance, with four pairs of barbels (whiskers) and wide, fleshy lips. The teeth are small and bristle-like. The eyes are small. The dorsal fin is long and continuous and extends two-thirds the length of the back. There is no adipose fin as in native catfishes. Anal fins are also long, but end in a lobe separate from the caudal fin (tail), which is rounded. Each pectoral fin has a strong, rigid spine at the front that helps the fish “walk.” Somewhat ungainly terrestrial locomotion is achieved by using the pectoral spines to Top: Walking catfish are native to parts of South and Southeast Asia. pull itself along while flexing (Adapted from Robins n.d.) Bottom: Walking catfish are invasive in the body back and forth. Florida. They have been collected in other states. (Adapted from Nico The scaleless body is usually 2009.) a drab gray or gray-brown with white flecks on the sides. Albino and calico colors are common in aquarium fishes, but wild populations revert to the natural gray. (All of the original walking catfish introduced into Florida were albinos.) The gills of walking catfish are specially structured with tree-like organs to permit their breathing on land and in stagnant water. Related or Similar Species. Native catfish, such as the marine hardhead catfish (Ariopsis felis) and gafftopsail catfish (Bagre marinus), as well as freshwater catfish such as the brown bullhead (Ictalurus nebulosus) and channel catfish (I. punctatus) could be mistaken for walking catfish. All native catfishes, however, possess a forked tail, an adipose fin just forward of the tail, and a dorsal spine. Introduction History. Walking catfish were first imported to Florida in the early 1960s for the aquarium trade. The introduction into local waters occurred in the mid-1960s when

200 n VERTEBRATES (FISH) adult fish escaped either from a fish farm in northeastern Broward County or from a transport truck carrying brood fish between Broward and Miami-Dade counties. Apparently purposeful releases were made by fish farmers elsewhere in Florida in 1967–1968 after the state prohibited the importation and possession of walking catfish. By 1968, walking catfish were established in three counties; 10 years after the first escapes, they were in almost 20 counties in the southern half of Florida. Their spread was facilitated by the network of canals and drainage ditches in southeastern Florida and their ability to cross land, especially on rainy nights. Aquarium releases are the likely source of introductions in other states. Habitat. Walking catfish may inhabit a variety of habitats, but they are most commonly associated with freshwater habitats in which most native species do not thrive. They are bottom-dwellers that become the dominants in warm, muddy ponds, swamps, canals, and ditches and tolerate stagnant, low-oxygen conditions. Since they can “walk” from pond to pond and also burrow into pond and river banks for a period of dormancy, they can also inhabit intermittent streams and isolated temporary ponds. They are essentially tropical fish and vulnerable to cold. Winter kills have been reported in Florida when water temperatures drop below 50°F (10°C). Diet. Walking catfish feed on large aquatic invertebrates, the eggs and larvae of amphibians and fish, and small fish. They are known to have invaded aquaculture farms to feed on fish. Life History. Walking catfish become sexually mature at about one year of age. Mass migrations and spawning seem to be linked to the rainy season. Nests are hollowed out in detritus or submerged vegetation and guarded by the adults. The up to 1,000 eggs laid are adhesive and stick to the substrate. Once the eggs have been fertilized, the male guards the nest, and the female hovers nearby to drive off intruders. Embryos hatch in about 30 hours and the fry stay under the protection of the parents for about five days, at which time the yolk-sac is absorbed and the young begin to forage. Catfish grow rapidly and, in Florida, usually reach a length of about 12 in. (30 cm). The largest reported walking catfish in the United States was about 20 in. (50 cm) long and weighed about 3 lbs. (1.4 kg). Impacts. When walking catfish were first released into Florida waters, they were forecast to become the most harmful introduction known so far. They were prolific, and because they could move across land, they dispersed rapidly. It was expected that they would outcompete native catfish species and cause the decline of some native amphibians. However, after an initial population explosion, numbers began to decline in the 1970s. Actual ecological impacts are unknown. They have not eliminated any native fish and indeed do not seem to have had any major negative effect on native fish or amphibian communities. It may be that their preference for ponds that partially dry up each year and stagnant bodies of water to which no natives are adapted has isolated them from native fish populations and reduced their effects. They do, however, have an economic impact on fish farmers, who must construct barriers to keep them out of their aquaculture ponds, and are still considered undesirable. The walking catfish has been nominated as among 100 of the “World’s Worst” invaders by the Invasive Species Specialist Group (ISSG). Management. All members of the walking catfish family are on the U.S. Fish and Wildlife Service’s list of Injurious Wildlife Species. Under the Lacey Act, it is a violation of federal law to import them into the United States without a permit. Some states have laws that make it illegal to possess a live walking catfish. Any walking catfish caught by anglers must be quickly killed. Fish fences keep walking catfish out of aquaculture ponds.

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Selected References Masterson, J. “Clarias batrachus (Walking catfish).” Smithsonian Marine Station at Fort Pierce, 2007. http://www.sms.si.edu/IRLspec/Clarias_batrachus.htm. Nico, Leo. “Clarias batrachus.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2009. Revised April 11, 2006. http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=486. Robins, Robert H. “Biological Profiles: Walking Catfish.” Florida Museum of Natural History, n.d. http://www.flmnh.ufl.edu/fish/Gallery/Descript/WalkingCatfish/WalkingCatfish.html. “Walking Catfish—Clarias batrachus.” MyFWS.com, Florida Fish and Wildlife Conservation Commission, Tallahassee, n.d. http://myfwc.com/wildlifehabitats/profiles/fish/nonnative-fish/walking -catfish/.

n Amphibians n African Clawed Frog Also known as: Upland frog, common platanna Scientific name: Xenopus laevis Family: Pipidae Native Range. Highlands of sub-Saharan Africa in Angola, Botswana, Burundi, Cameroon, Central African Republic, Democratic Republic of the Congo, southwestern Kenya, Lestho, Malawai, Mozambique, Namibia, eastern Nigeria, Rwanda, South Africa, Swaziland, Uganda, Zambia, and Zimbabwe. Absent from Congo Basin and warmer lowlands of East Africa. Imports to the United States originated in South Africa. Distribution in the United States. Disjunct populations are established in at least seven counties in southern California, and reported from others. A single population is established in artificial ponds at a golf course in Tucson, Arizona. African clawed frogs have been collected in Colorado, Florida, Massachusetts, North Carolina, Nevada, New Mexico, Texas, Utah, Virginia, Wisconsin, and Wyoming, but no established populations are known from these states. Description. The African clawed frog has a flattened body and relatively small head. It lacks a visible external ear drum (tympanum) and has no tongue. Its eyes are small and lidless, located near the top of the head. The forefeet have four thin, unwebbed fingers that usually point forward. The large hind feet have five fully webbed toes, the inner three of which possess sharp, black claws. The skin is very smooth and slippery. The back is a mottled olive-brown or gray, and the belly is cream colored. The lateral lines seem stitched along the back. Snout to vent length is from 2.0 to 5.5 in. (5–14 cm.) Tadpoles of this species are unique. They are transparent, so the internal organs are visible. Barbels occur at the mouth, making them resemble small catfish. The tail ends in a filament. They usually swim head down, vibrating the tail filament to stir up plankton. Tadpoles grow to about 1.5 in. (3.8 cm) long. Related or Similar Species. None. No native American frog or toad has clawed hind limb toes. No native amphibians have transparent tadpoles or tadpoles with long barbells. Introduction History. The African clawed frog was introduced to laboratories around the globe in the 1940s and 1950s after it was discovered it could be used as a reliable test for human pregnancy. An injection of urine from a pregnant woman stimulated a female frog

202 n VERTEBRATES (AMPHIBIANS) to lay eggs. As the demand grew, the frog was bred in captivity, so that most free-living populations outside the natural range of the species are actually feral stock. The clawed frogs are easy to care for and disease resistant, and in the 1950s and 1960s, they gained a foothold in the pet trade. It is still an important research animal, used primarily for studies of developmental, cell, and molecular biology. Most introductions to the wild were intentional releases from laboratories once other techniques to determine human pregnancy were devised. Pets, no longer wanted by their owners, were also released. The first feral African clawed frog was found in Orange County, California, in 1968. Independent introduction events occurred in five counties (Los Angeles, Orange, Riverside, San Diego, and Santa Barbara); in 25–30 years, the frogs spread throughout most of the drainage systems into which they were first reTop: The African clawed frog is native to the uplands of sub-Saharan leased. San Bernadino and Africa. (Adapted from range map of Xenopus laevis at http:// Ventura counties were invaded www.iucnredlist.org/apps/redlist/details/58174/0/rangemap.) Bottom: from neighboring counties. It is Self-sustaining populations of African clawed frog occur in California expected that they will continue and Arizona. It has been collected in several other states, where, to date, to spread along the many irrino populations have become established. (Adapted from Somma 2005.) gation canals and drainage ditches in southern California. In Arizona, African clawed frogs were deliberately introduced to man-made ponds in Arthur Park Golf Course, in Tucson, Pima County, in the late 1960s, and they persist there. Spread to other bodies of water has been inhibited by the surrounding expanse of desert. Other states where the frog was introduced but never became established, with the recorded dates of introduction, are: Colorado, 1990; Florida, 1964; Massachusetts, 1993; North Carolina, 1990s; Virginia, 1980s (eradicated 1987–1988); Wisconsin, 1972. Habitat. The African clawed frog spends almost its entire life in aquatic habitats, leaving water only if forced to migrate when a water body dries up or is poisoned. They may be found in all types of aquatic situations except fast-moving rivers and water bodies with predatory fish. They tend to prefer eutrophic ponds, both natural and artificial, slow

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streams, and natural waterways that are frequently disturbed or experience high environmental variability. They are salt tolerant and can live in estuaries. Although they find optimal climatic conditions in Mediterranean climates and water temperatures between 60° and 80°F (15–27°C), adults can tolerate temperatures ranging from 32° to 86°F (0–30°C) and populations have persisted under winter ice. Tadpoles survive in water temperatures ranging from 50° to 86°F (10– 30° C). Adults can aestivate for African clawed frogs have flattened bodies and lack visible external ear periods of up to eight months drums. (Todd Battey.) and go without food for a year. Eggs and tadpoles are viable in both acidic and alkaline water (pH 5–9). Diet. Adults feed on slow-moving aquatic invertebrates that they suck into their mouths. They will also scavenge dead and dying arthropods and take small fish and tadpoles, including those of their own species. They rely on the lateral line system to detect scents in the water and the movement of prey. Forelimbs gather food into the mouth, while the strong, clawed hind legs shred larger prey items into ingestible sizes. Tadpoles are filter-feeders. They extract small phytoplankters from open water. Food includes one-celled algae such as diatoms, protozoans, and bacteria. Life History. African clawed frogs in California breed from January through November. A peak occurs in April and May. Males vocalize underwater during the evening to call females. The mating call alternates long and short trills. The female either accepts him with a rapping sound or rejects him with a slow ticking sound. (Very seldom does this answering behavior happen with any other animal.) Mating usually takes place at night. Unlike most other frogs, the mating embrace or amplexus is pelvic. Over the course of the next 3–4 hours, the female releases, one at a time, hundreds of eggs that, fertilized by the male, adhere to plants or other underwater structures. The eggs grow into tadpoles and hatch in 3–4 days. The length of the larval stage is 5–12 weeks. Tadpoles are weak swimmers prone to predation by fish; they congregate in schools in deeper water to feed. As the tadpole metamorphoses, the tail is absorbed, providing nutrition for the developing froglet. Metamorphosis takes 4–5 days. Sexual maturity is reached 6–10 months after metamorphosis. African clawed frogs may live 9–15 years. Impacts. The African clawed frog may be a threat to native amphibians and fish in California and the Southwest since it preys upon tadpoles and fish fry. Its range overlaps with such vulnerable species as western toad (Bufo boreas), red-spotted toads (Bufo punctatus), California red-legged frogs (Rana draytoni), Pacific treefrogs (Pseudacris regilla), and western spadefoot toads (Spea hammondi). It is known to eat larvae and recently metamorphosed western toads, but negative impacts on California red-legged frogs, though claimed, have not been verified. Observations of African clawed frogs preying on fish are rare, but do include consumption of the federally endangered tidewater goby (Eucyclogobius newberryi),

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African Clawed Frog as Pharmacopoiea

T

he African clawed frog has long been used as a research animal because it is easy to care for and breeds rapidly, and the development of its transparent embryos is easy to observe. In 1987, Dr. Michael Zasloff discovered that the skin of the African clawed frog has glands that secrete a broad-spectrum antimicrobial chemical effective against viruses, bacteria, fungi, and protozoa. When first discovered, this defensive mechanism represented a totally new way that vertebrates were able to protect themselves against infection. Previously, it was believed only the immune system attacked invading pathogens. The frog skin chemicals work by creating a hole in the target’s cell membrane, causing the cell contents to leak out. Dr. Zasloff isolated two peptides from the skin of the African clawed frog and named them magainins, from the Hebrew word magain, meaning shield. Magainins were synthesized and manipulated in the laboratory to create thousands of related antibiotics. There was much hoopla in the 1990s about their potential use in new drugs to combat a variety of human infections. Experiments showed that magainins killed bacteria such as E. coli, staphylococci, streptococci, and enterobacteria. They gave promise in combating colon cancer. A topical cream proved effective as a treatment for diabetic foot ulcers. Magainins in toothpaste might fight dental plaque. They might control the tuberculosis bacillus or the plasmodium that causes malaria, or they could work as a spermicide that not only protects against pregnancy but also against sexually transmitted diseases. Although no magainin-containing drugs have completed the whole arduous course through animal trials and human safety tests to FDA approval and the drug store shelf, their discovery in the African clawed frog opened new paths of research in animalderived antibiotics and pointed to future discoveries of antibiotics and other helpful compounds in what remains of Earth’s biodiversity. Since 1987 almost all frog species tested have been found to produce related chemicals in their skin and in their digestive tracts; and other animals have found to produce similar compounds in their saliva. Source: Altman, Lawrence K. “Curiosity on Healing in Frogs Leads to a Gain in Antibiotics.” New York Times, July 31, 1987. http://www.nytimes.com/1987/07/31/us/curiosity-on-healingin-frogs-leads-to-a-gain-in-antibiotics.html?ref=lawrencekaltman

arroyo chub (Gila orcutti), and another federally endangered fish, the unarmored threespine stickleback (Gastaerosteus aculeatus williamsoni). Were African clawed frogs to get into the isolated pools containing desert pupfish (Cyprinodon spp.), those rare fish would likely be at severe risk. Many scientists believe African clawed frogs carried the fungus Batrachochytrium dedrobatidis (see Fungi, Chytrid Frog Fungus) around the globe. This fungus is a major cause of the worldwide decline and extinction of frogs and toads. African clawed frogs are immune to the fungus, which is native to their African habitats. Museum specimens dating to 1938 show evidence of chytridiomycosis, the skin disease associated with it. Management. Most efforts to eliminate clawed frogs in California have not been successful. Permanent eradication is known in only one instance, when an artificial pond on the University of California, Davis, campus was poisoned by the California Department of Fish

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and Game. Elsewhere, poisoning has not worked. At Vasquez Rock in the upper Santa Clara River drainage, the frogs simply left the water after rotenone was applied. Other methods of control include draining ponds, removing frogs by seine or traps, electroshocking, and introducing predatory fish; but none have proved effective in eliminating frogs or preventing their reintroduction.

Selected References Crayon, John J. “Xenopus laevis (Daudin, 1802) African Clawed Frog.” AmphibiaWeb: Information on amphibian biology and conservation. Berkeley, California, 2009. http://amphibiaweb.org/. Garvey, Nathan. “Xenopus laevis African Clawed Frog.” University of Michigan Museum of Zoology, 2000. http://animaldiversity.ummz.umich.edu/site/accounts/information/Xenopus_laevis.html. Measey, John. “Xenopus laevis (Amphibian).” IUCN/SSC Invasive Species Specialist Group (ISSG) Global Invasive Species Database, 2006. http://www.issg.org/database/species/ecology.asp?si=150. Rorabaugh, Jim.“African Clawed Frog Xenopus laevis.” Online Field Guide to the Reptiles and Amphibians of Arizona, 2008. http://www.reptilesofaz.org/Turtle-Amphibs-Subpages/ h-x-laevis.html. Somma, Louis A. “Xenopus laevis.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2009. Revised March 24, 2005. http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=67. Willigan, Erin. “African Clawed Frog (Xenopus laevis).” Introduced Species Summary Project, Columbia University, 2001. http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/inv_spp_summ/ xenopus_laevis.htm.

n American Bullfrog Scientific name: Lithobates catesbeianus Synonym: Rana catesbeiana Family: Ranidae Native Range. Central and eastern United States and southern parts of Ontario and Quebec provinces, Canada. Distribution in the United States. The American bullfrog has become established outside its native range in Arizona, California, Colorado, Hawai’i, Nebraska, Nevada, Oregon, Utah, and Washington. It has also been introduced to locations where it was not historically found within its natural range in Massachusetts (on the islands of Nantucket and Martha’s Vineyard, and in the Wellfleet Bay sanctuary on Cape Cod), Iowa (in the DeSoto National Wildlife Refuge on the Missouri River), and New Jersey (in the Cape May National Wildlife Refuge). Description. Adult bullfrogs are green to brownish green, with dark blotches and bars on the back and legs. The upper jaw is often a light green. The belly is cream to yellow. During the breeding season, the throat of the male is yellow, while that of the female is white. The absence of dorsolateral folds is diagnostic. However, there is a short fold in the skin running from the eye, over the eardrum to the forelimb. The eardrum or tympanum is conspicuous and exhibits sexual dimorphism. In males, the tympanum is larger than the eye; in females, it is the same size as or smaller than the eye. The hindfoot is fully webbed with the exception of the last joint of the fourth toe. The tadpole is large (up to 6 in. or 15 cm long). Its back is yellow green and has black spots; the belly is lighter. The dorsal fin is arched. The call of the bullfrog is deep and very loud; it is usually described as “jug-o’rum” or “br-wum.” They also sound a loud squeak of alarm before jumping into the water when

206 n VERTEBRATES (AMPHIBIANS) surprised. Bullfrogs are active both day and night and are highly aquatic, rarely found out of the water. The bullfrog is the largest frog native to North America. From snout to vent, the length of adults ranges from 3.5 to 8 in. (9–20 cm), the largest individuals being female. They may weigh more than 1 lb. (0.5 kg). They are celebrated jumpers, and their long legs are considered a delicacy; they are often hunted and farmed for meat. Related or Similar Species. The green frog (Lithobates [=Rana] clamitans) is much smaller (adults only 2–4 in. or 5–10 cm, snout to vent) and has the prominent dorsolateral folds characteristic of most North American frogs. Its distribution is similar to that of the natural range of the American bullfrog. Introduction History. Bullfrogs were first introduced to California in 1890s and Colorado in the early 1900s. By the end of the 1920s, they were common on the lower Colorado Top: The American bullfrog is native to the central and eastern United River near Yuma, Arizona. The States and adjacent areas of Canada. Bottom: American bullfrogs have pathways of introduction are been transplanted beyond their native range into all western states largely unknown. In Colorado, (except Alaska), Hawai’i, and Puerto Rico. (Both maps adapted from bullfrog tadpoles at fish hatchMcKercher 2009.) eries may have contaminated fish stockings in trout streams and lakes. Other possible means of introduction include the aquarium trade, frog-farming operations, and the stocking of farm ponds to control agricultural pests. They may have been deliberately released to provide a new game animal or introduced as a living feature of ornamental ponds. Once in the wild, bullfrogs are able to disperse through entire drainage systems. In some western states, the competitive advantage that the American bullfrog has over native frogs is enhanced by the introduction of nonnative fishes, such as bluegill sunfish (Lepomis macrochirus). In the Pacific Northwest, bluegills and other sport fish were stocked in lakes that had no native fishes. The nonnative fish eat the tadpoles of native frogs, but leave bullfrog tadpoles alone. Bullfrogs coevolved with these alien fishes and are unpalatable to them. Furthermore, the sunfish consume the nymphs of native dragonflies, species that do prey upon bullfrog tadpoles.

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A. Adult American bullfrogs have no folds on the back or sides, but a short fold of skin does occur from the eye over the conspicuous external eardrum to the forelimb. (Ilias Strachnis/Shutterstock.) B. The tadpole is very large and has an arched dorsal fin. (Tommounsay/iStockPhoto.)

Bullfrogs have been introduced to Mexico, the Caribbean, South America, Europe, and Asia. Habitat. Shallow, still waters are preferred, especially where abundant aquatic vegetation provides shelter. Bullfrogs are thus found in marshes and along the shores of lakes, ponds, slow-moving rivers, and reservoirs or other impoundments. They need warm water for breeding, and tadpoles prefer non-vegetated areas. Tadpoles are able to overwinter in water beneath a cover of ice. Adults hibernate in mud during cold weather. Diet. Adult bullfrogs are carnivorous and tend to eat whatever they can catch with their large sticky tongues, including insects, crayfish, fish eggs, eggs of amphibians, tadpoles, and frogs, including other bullfrogs. They also take snakes, birds, bats, and mice. Tadpoles are mostly herbivorous and feed on cyanobacteria, algae, other plant material, and small aquatic invertebrates. Life History. American bullfrogs have a long breeding season, from May to July in northern states and from February to October in warmer areas. A female deposits up to 20,000 eggs in a broad foamy sheet in warm, quiet water. Fertilization is external. The raft of jelly-coated eggs may stretch 3 ft. (1 m) in diameter. It floats until just before hatching, when it sinks onto underwater vegetation. Tadpoles hatch out 3–5 days after fertilization. The gilled tadpoles develop slowly, and those in colder climes overwinter at least once. The transformation from tadpole to froglet, when the tail is slowly absorbed, may take 1–3 years. The new froglets measure about 2 in. (5 cm) long. Bullfrogs become sexually mature two years later, and live 7–9 years in the wild. Impacts. The introduction of the American bullfrog to western states has likely exacerbated problems related to the demise of native frogs because bullfrogs feed on frogs and tadpoles. Tadpoles may significantly alter aquatic community structure because they feed heavily on algae. In Arizona, predation by bullfrogs has contributed to the extirpation of populations of native leopard frogs and garter snakes. Most vulnerable are the Mexican garter snake (Thamnophis eques megalops), and the federally threatened Chiricahua leopard frog (Rana chiricahuensis). Introduced bullfrogs may also spread chytridomycosis, a fungal disease of the skin implicated in the decline of amphibians worldwide (see Fungi, Chytrid Frog Fungus). ISSG has nominated them as one of 100 of the “World’s Worst” invaders. Management. Bullfrog populations are often managed as fisheries, and harvesting limits population growth. Adults can be taken with gigs, nets, traps, bow and arrow, and guns;

208 n VERTEBRATES (AMPHIBIANS) and they can be caught by hand. Spotlighting at night is a common practice since frogs are immobilized by bright lights. Larvae can be killed by the same poisons used against fish. Suctioning off the egg masses can be tricky but effective. New introductions to areas where bullfrogs are not yet present should be prohibited.

Selected References “Alien Species in Cahoots.” U.S. Geological Survey News Release, March 13, 2003. http://fresc.usgs.gov/ news/newsreleases.asp?NRID=3. Bruening, S. “Rana catesbeiana.” Animal Diversity Web, University of Michigan Museum of Zoology, 2002. http://animaldiversity.ummz.umich.edu/site/accounts/information/Rana_catesbeiana.html. Crayon, John J. “Rana catesbeiana (Amphibian).” Global Invasive Species Database, IUCN/SSC Invasive Species Specialist Group, 2005. http://www.issg.org/database/species/ecology.asp?si=80&fr =1&sts. McKercher, Liz, and Denise R. Gregoire. Lithobates [=Rana] catesbeianus. USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2009. Revised March 7, 2011. http://nas.er.usgs.gov/queries/ FactSheet.asp?speciesID=71. Murphy, Martin. “North American Bullfrog (Rana castesbeiana).” Introduced Species Summary Project, Columbia University, 2003. http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/ inv_spp_summ/Rana_catesbeiana.htm. Rorabaugh, Jim. “American Bullfrog Rana catesbeiana.” Online Field Guide to the Reptiles and Amphibians of Arizona, 2008. http://www.reptilesofaz.org/Turtle-Amphibs-Subpages/ h-l-catesbeianus.html.

n Coqui Also known as: common coqui, coquı´ comu´n, Puerto Rican treefrog Scientific name: Eleutherodactylus coqui Family: Leptodactylidae Native Range. Puerto Rico. Native to a variety of habitats and elevations. Distribution in the United States. Coqui are established in Hawai’i on Hawai’i Island, Kaua’i, Maui, and O’ahu. They are established but noninvasive in Florida, where they tend to die off during winter freezes. Established populations also occur on St. Croix, St. John, and St. Thomas, U.S. Virgin Islands. Description. A small but very loud frog. Coqui are quite variable in color. The back may range from light yellow to dark brown and may or may not be mottled with black spots. There may be a cream line running along the midline of the back from the snout to the hind legs or an indistinct dark “M” between the shoulders. The underside is light with brown stipples. Eyes are gold or golden brown. The toes have suction cup-like pads like those of true treefrogs (family Hylidae). Breeding males are slightly larger than 1 in. (34 mm) from snout to vent; females average about 1.5 in. (41 mm). It appears that the average size of coqui frogs is increasing in Hawai’i, since frogs continue to grow throughout their lives and may live up to seven years. Coqui have been on the Big Island for 10 years. They also tend to be larger at higher elevations. There is no tadpole stage. The mating call of the male coqui is a rapid and loud “ko-KEE.” Males begin to call at dusk and may continue all night, especially if it is raining. According to one report, the sound measures as much as 80–90 decibels, comparable to a lawn mower. Related or Similar Species. In Hawai’i, the coqui most resembles another exotic amphibian, its close relative the greenhouse frog (Eleutherodactylus planirostris). Greenhouse frogs

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have narrower snouts, a narrower body shape, claw-like toes, red eyes, and a wartytextured skin. Adults are usually a mottled copper color and are less than 1 in. (2.5 cm) long. Most importantly, they have a soft bird- or cricket-like chirp. They live on the ground and are not considered invasive. In Florida, coqui might be confused with native treefrogs. Introduction History. The coqui was probably introduced to the island of Hawai’i accidentally around 1988 in a shipment of horticultural plants such as bromeliads from Puerto Rico. From a few infected nurseries, the coqui was likely spread in landscaping materials to other sites and other islands. Populations grew rapidly and expanded beyond the sites of initial entry due of lack of predators (e.g., owls, snakes, tarantulas) on the islands. By 2003, there were more than 200 infestation sites on the Big Island, 40 or more on Maui, 5 on O’ahu, and 1 site on Kaua’i. These sites include Top: The coqui is native to Puerto Rico. Bottom: The loud little arboreal commercial plant nurseries, frog is invasive in Hawai’i. The expansion of populations in Florida the grounds of resort hotels, seems to be prevented by cold winter weather. (Adapted from Somma ornamental plantings in parks, 2009.) and in native forest. Habitat. Coqui frogs are found in Hawai’i in a variety of ecological zones at elevations ranging from sea level to 4,000 ft. (1,220 m). Most populations are in or near horticultural sites, although they spread from nurseries, resorts, and residential areas into natural areas on public lands. By day, they hide in shady, thick moist brush, leaf litter, dead leaves on banana plants, empty flower pots, or holes in porous rock. They nest in cavities, folded or rolled leaves, PVC pipe, or other sheltering structures. Coqui seem to especially like broadleaf plants such as heliconias (Heliconia spp.), Koster’s curse (Clidemia hirta), Loulu palms (Pritchardia spp.), silktree (Albezia julibrissin), split-leaf philodendrons (Monstera spp.), and ti (Cordyline terminalis). Adults prefer to be 3–9 ft. (1–3 m) above the ground; juveniles are usually found less than 4 ft. (1 m) above the ground. Since they have no tadpole stage, they do not require standing water for breeding. Diet. Insects and other terrestrial invertebrates.

210 n VERTEBRATES (AMPHIBIANS) Life History. Breeding occurs all year, but tends to concentrate during the rainy season. Coqui use internal fertilization. The female lays a clutch of about two dozen eggs in a protected, elevated cavity. Males guard the eggs and keep them from drying out. Four to six clutches may be produced in a year, usually one every two months. The fertilized eggs undergo direct development to tiny (approx. 0.5 in. or 1.25 cm long) froglets in 2–3 weeks. Coqui froglets are sexually mature in about eight months. This coqui is resting in a tank bromeliad. (Rogeliao Doratt/USDA.) Impacts. Hawai’i has no native frogs, so any introduced frog poses the potential to disrupt native ecosystems. Experiments have shown that consumption of leaf-eating insects by coqui can increase foliage production and decomposition rates, thereby increasing nutrient cycling rates. It is possible that coqui will consume endemic insects and spiders, some of which are already on the verge of extinction and some of which are important pollinators of Hawai’i’s endemic flora. It could compete with native Hawaiian birds, most of which are insectivorous. There is also concern that coqui might provide a food source for the nonindigenous brown tree snake (Boiga irregularis), should it invade the islands. By far the greatest problem with the coqui is noise. Tourists and residents complain of sleepless nights. Property values have declined in infested areas. The tourist and real estate industries are threatened. Controls to prevent the further spread to the coqui could be deleterious to the floriculture and nursery industries, the main pathways of dispersal for this tiny invader. The combined value of the tourism, floriculture, and real estate industries which are at risk in Hawai’i is many millions of dollars. For its potential ecological and economic impacts, the coqui has been nominated as among 100 of the “World’s Worst” invaders by IUCN/Species Survival Commission’s Invasive Species Specialist Group (ISSG). Management. Small populations may be controlled by hand-capture and trapping. Larger infestations may be managed by spraying landscape plants with hot water (113°F) or dipping potted plants in hot water. A solution of citric acid will kill adults and eggs and is approved for use by the EPA. Prevention is key. Hawaiians need to eliminate the habitats that coqui prefer around their homes and vacation spots. They are encouraged to compost yard wastes, prune and thin shrubbery, remove dead leaves especially from large-leaved plants, and remove empty pots and other containers that collect rainwater during dry seasons. The inter-island transport of coqui frogs is now prohibited in Hawai’i. If strict controls including certification of frog-free flowers and plants were to be placed on floriculture exports—a not unreasonable prospect, this would create a financial hardship on one of Hawai’i’s major industries.

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Selected References Chun, S., A. H. Hara, and R. Y. Niino-DuPonte. “Greenhouse Frog or Coqui Frog?” College of Tropical Agriculture and Human Resources, University of Hawai’i at Manoa, 2003. http://www2.ctahr .hawaii.edu/oc/freepubs/pdf/coqui_id.pdf. “Control of Coqui Frogs in Hawai’i.” Department of Plant and Environmental Protection Sciences, College of Tropical Agriculture and Human Resources, University of Hawai’i at Manoa, 2008. http://www.ctahr.hawaii.edu/coqui/. Kraus, Fred, Earl W. Campbell, Allen Allison, and Thane Pratt. “Eleutherodactylus Frog Introductions to Hawaii.” Herpetological Review 30 (10): 21–25, 1999. Available online at http://www.hear.org/ articles/pdfs/herp_review_frogs_1999v30n1.pdf. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Eleutherodactylus coqui (Amphibian).” ISSG Global Invasive Species Database, 2005. http:// www.issg.org/database/species/ecology.asp?fr=1&si=105. Somma, Louis A. “Eleutherodactylus coqui.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2009. Revised May 14, 2006. http://nas.er.usgs.gov/queries/FactSheet.asp ?speciesID=60.

n Cuban Treefrog Also known as: Giant tree frog, rana platernera Scientific name: Osteopilus septentrionalis Synonyms: Trachycephalus insulsus, Hyla septentrionalis Family: Hylidae Native Range. Cuba, Isla de Pinos, the Bahamas, and the Cayman Islands. Distribution in the United States. Established in Florida. Also established in Puerto Rico and St. Croix and St. Thomas, U.S. Virgin Islands; collected from Georgia, but apparently not established there. Single waifs have been reported from Colorado, Indiana, Maryland, and Virginia. A report of a population on O’ahu, Hawai’i, has not been verified. Description. The Cuban treefrog is the largest treefrog in the United States. It has very large toe pads equal in size to the eardrum (tympanum). The very large eyes of the Cuban treefrog give them a “bug-eyed” look. The back is warty, like a toad, and the belly is granular. A skin fold extends from the eye rearward to the tympanum. Adults can be distinguished from all native treefrogs because the skin on the top of the head is fused to the skull. Color varies from gray to gray-green or tan-brown, or even cream, and individuals are able to change color rapidly. The body is usually heavily mottled and there are often stripes on the backside of the legs. A yellowish tinge occurs where the legs join the body. The rear toes are slightly webbed, and there is a distinct tarsal fold along the entire ankle (tarsus). Most adults in Florida are from 1 to 4 in. (2.5–10 cm) long, although adult females may grow to 6 in. (15 cm) or more. Juveniles are difficult to identify because they lack warts and strong patterning. Sometimes they lack the lateral stripe that is found on many native treefrogs. Tadpoles have round bodies with dark or black backs. The intestinal coil is visible through the lightcolored belly. The tail is pigmented with lighter areas near the point of attachment to the body. Scattered dark flecks appear on the wide fin. The mating call of the male treefrog is a rasping snarl of varied pitch. It has been described as sounding like a squeaky door. The male’s vocal sac looks like a double bubble. Males also will call during the day when it rains.

212 n VERTEBRATES (AMPHIBIANS) Cuban treefrogs secrete a sticky substance that can irritate the skin and mucus membranes of people. The burning and itching sensation that results can last for an hour or more. Wash your hands after handling one. Related or Similar Species. In Florida, two native species could be mistaken for Cuban treefrogs. The green treefrog (Hyla cinera) has a smooth, bright-green skin. It has a pointed snout and a clear white line along each side of the body. The breeding call consists of a bell-like ringing, repeated many times. Maximum length is about 2.5 in. (6 cm). Squirrel treefrogs (Hyla squirella) are much smaller, adults being only about 1.5 in. (4 cm) long. They, too, can change their color, but are usually are muddy green on the back; belly and feet are light and spotted. Like all indigenous treefrogs, they have a single, rounded, balloon-like vocal sac. The breeding call sounds like a duck, while the rain call sounds like a chattering squirrel. Introduction History. Cuban Top: The native range of the Cuban treefrog consists of Cuba, Isla de Pinos, the Bahamas, and the Cayman Islands. Bottom: Cuban treefrogs treefrogs were in Key West, are established in Florida and Puerto Rico and possibly on O’ahu in Florida, sometime before 1928. Hawai’i. Individual treefrogs have been collected in a number of other Most likely they arrived as accistates. (Adapted from Somma 2009.) dental hitchhikers in shipping crates from the Caribbean. By the mid-1950s, they had spread through the keys to Key Largo. The first specimen from mainland Florida was collected in 1951. By the 1970s, they were being found throughout southern Florida, and in 2007, breeding populations occurred as far north as Cedar Key on the Gulf side of the peninsula and Jacksonville on the Atlantic side. Individuals have been reported in Georgia and South Carolina. Cuban treefrogs disperse as stowaways on horticultural plants (especially palm trees), building materials, cars, trucks, and boats. They respond to tropical storms and hurricanes by immediately breeding and dispersing. It is expected that they will continue to spread along the Gulf coast and then move southward into Mexico. Northward expansion into the United States seems to be checked by cooler climatic conditions. Habitat. Cuban treefrogs thrive in both natural and man-made habitats. In Florida, they can be found in swamps and on hardwood hammocks as well as in pine forests. In

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A. The skin on the head of the Cuban treefrog is fused to its skull. (Mike Pingleton, University of Illinois at Urbana-Champaign, Bugwood.org.) B. The very large toe pads are characteristic of this treefrog, which often invades homes. (Wayne Smaridge.)

residential areas, they are most frequently seen near ornamental ponds and near outside lighting, where they wait on walls, windows, porches, and potted plants to catch insects. When they get into homes, they are often encountered in the toilet. They also inhabit orange groves and plant nurseries. Active at night, by day they hide in tight, moist areas such as cellars, cisterns, drains, and plants. Diet. These frogs are ambush predators that feed mainly on insects, spiders, and several of Florida’s native treefrogs. They are also cannibalistic. Toads, lizards, and small snakes are additional items reportedly consumed by Cuban treefrogs. Tadpoles are omnivores and may consume the eggs and tadpoles of native frogs and even those of their own kind. Life History. The breeding season in Florida extends from May to October. Breeding is stimulated by warm summer rains. Breeding events usually last only one night. Eggs are deposited as a thin floating sheet in warm quiet waters of just about any size that lack predatory fish. Their gelatinous films of eggs can be found in ponds, ditches, abandoned swimming pools, and the stagnant waters of discarded containers. There is no parental care. Tadpoles hatch about two days later. The new hatchlings have a body length of about 0.05 in. (1.2 mm) and a tail about 0.15 in. (3.8 mm) long. The tadpoles metamorphose into small froglets in 3–8 weeks; the actual rate is determined by water temperature. At metamorphosis, they are about 1 in. (26–28 mm) long. Males mature when they are about 1.5 in. (40 mm) long; females mature more slowly and therefore are much larger than males at maturity. Mature males participate in all breeding events and typically do not live as long as females, which do not participate in every breeding event. Mature males may only live two months, whereas mature females may survive more than two years.

214 n VERTEBRATES (REPTILES) Impacts. Cuban treefrogs could negatively affect native treefrog species through predation and/or competition for food and space. Anecdotal evidence suggests they have replaced green frogs and squirrel frogs in residential areas. But mostly these frogs are a nuisance in and around homes and other buildings. Their calls, though not particularly loud, can be annoying. As they feed and defecate on windows and walls, they create unsightly messes. They enter homes on house plants, by jumping through an open window or door, or by making their way into bathroom vent pipes. They end up in the toilet, a startling surprise for whomever raises the lid. They are also known to have clogged sink drains. Perhaps the most serious feature of these invaders is the irritating secretions from their skin, which can cause strong reactions from people with asthma or allergies. Management. Around the home, Cuban treefrogs can be caught by hand or attracted into traps of PVC pipe and then, when it is determined the culprit really is this exotic invader, humanely euthanized. Potential breeding sites can be eliminated by removing any containers that could collect water. Small-mesh aquarium nets can be used to scoop out eggs and dump them on the ground to dry out. Other methods to prevent the spread or breeding of the Cuban treefrog include screening cisterns and fumigating imported plants. Monitoring its dispersal and taking quick action to eradicate new populations may slow its spread.

Selected References Johnson, Steve A. “The Cuban Treefrog (Osteopilus septentrionalis) in Florida.” University of Florida, IFAS Extension, 2007. http://edis.ifas.ufl.edu/uw259. National Biological Information Infrastructure (NBII), Comite´ franc¸ais de l’UICN (IUCN French Committee), and IUCN SSC Invasive Species Specialist Group (ISSG). “Osteopilus septentrionalis (Amphibian).” ISSG Global Invasive Species Database, 2008. http://www.issg.org/database/species/ ecology.asp?si=1261&fr=1&sts=&lang=EN. Somma, Louis A. “Osteopilus septentrionalis.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2009. Revised February 11, 2009. http://nas.er.usgs.gov/queries/FactSheet.asp ?speciesID=57.

n Reptiles n Brown Anole Also known as: Cuban brown anole, Bahamian brown anole Scientific name: Norops sagrei Synonym: Anolis sagrei Family: Polychrotidae Native Range. Cuba; the Bahamas; Cayman Brac; Little Cayman; Swan Island, Honduras. Distribution in the United States. Established throughout peninsular Florida and in coastal counties of southernmost Georgia. Populations are reported from Hawai’i, Louisiana, North Carolina, South Carolina, and Houston, Texas; but establishment in those states is uncertain. Description. This is a small anole lizard adapted for life on the trunks of trees and on the ground. It has long toes with relatively small toe pads that enable it to run swiftly and jump. The snout is short and rounded. It is distinguished as an anole by its dewlap, the red-orange or yellow throat fan. This is much larger in males than females and, when not extended,

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appears as a pale line on the throat. A crest along the neck and back can be erected. The somewhat laterally compressed tail sometimes bears a crestlike ridge. The stripe down the middle of the back is often boldly patterned with waves, zigzags, or diamonds in females, but it is indistinct in males. Body color varies from pale gray to dark brown and even black; mottling, spots, chevrons, or light-colored lines may be present. Brown anoles can change their skin color in a matter of minutes in response to environmental stimuli, aggression, or reproductive activity. Adult males have a snoutvent length (SVL) of about 2.3 in. (6 cm) and weigh about 0.25 oz. (6–8 g). Females are usually less than 2 in. (5 cm) snoutvent, and weigh 0.1 oz. (3–4 g). The tail is normally longer than the body, giving a total length of 5–8 in. (13–21 cm); but it can be broken off and regrown, in which case it will be smaller. Brown anoles are active during the day and commonly Top: The brown anole’s native range consists of Cuba, Isla de Pinos, the seen head-down on a low perch Bahamas, Cayman Brac, Little Cayman, and Swan Island, Honduras. waiting to ambush prey or bob- Bottom: Brown anoles have established populations throughout bing their heads and flashing peninsular Florida and in some of the southernmost counties of their dewlaps in territorial and Georgia. Although reported from a number of other states, they currently do not seem to have established populations elsewhere. mating displays. When startled, (Adapted from Savannah River Ecology Laboratory, n.d.) these alert and quick lizards run away on the ground. Related or Similar Species. The only anole native to the temperate southeastern United States is the green anole (Anolis carolinensis). It tends to be smaller and more delicately built than the brown anole. The head and snout are more slender. It is often bright green, but can change color to a brown that might lead one to mistake it for a brown anole. In the Miami area, eight other introduced anoles might be confused with the brown anole. This is especially true of the bark anole (A. distichus), which is smaller and strictly arboreal. Brown anoles are sometimes erroneously referred to as chameleons because of their ability to change color, but true chameleons are Old World reptiles with prehensile tails, mittenlike feet, and eyes mounted on turrets that move independently of each other.

216 n VERTEBRATES (REPTILES)

A. The brown anole has a short, rounded snout. Its long toes with small toe pads enable it to run quickly and jump, adapting it for life in the trees and on the ground. (John Anderson/iStockPhoto.) B. The brown anole is typically seen in a head-down position on the lower trunks of trees. The large dewlap identifies it as an anole. (David Sischo/iStockPhoto.)

Introduction History. The brown anole was first reported from the Florida Keys in 1887. In the 1940s, it was introduced in at least six different ports in Florida. Most probably, it was a stowaway on ships. Both major subspecies, the Cuban brown anole (N. sagrei sagrei) and the Bahaman brown anole (N. sagrei ordinatus), arrived on the mainland, but through subsequent interbreeding, they have lost their genetic distinctiveness. The brown anole has continued to expand its range northward, hitchhiking on motor vehicles and in ornamental plants. Habitat. The brown anole is a habitat generalist that prefers open vegetation in moist areas such as forest edge, disturbed sites, and the edge habitats created in urban and suburban settings. They spend much of their time on the ground or on trees just a few feet above the ground. This is a tropical to subtropical species; its northern limits seem to be controlled by cold winters. Diet. Brown anoles are predators that feed on a wide range of animals, including annelid worms, amphipods, isopods, moths, crickets, beetles, flies, spiders, snails, and small vertebrates. They also eat the hatchlings of the green anole and probably of their own species. Life History. Brown anoles begin to establish breeding territories in March and April and defend them for another 5–6 months. Within each male’s territory may be two or more female territories. Males fight intensely to ward off other males, locking jaws and knocking one another off their perches. The dewlaps are displayed as part of the aggression ritual and as courtship behavior to attract females. Females lay a single round egg at time, once every week or two, throughout the breeding season. The egg is deposited under moist decaying leaf litter on the ground. It takes 2–3 months for them to hatch; the first usually

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Anoles and Evolution

A

noles in general are excellent dispersers, and their spread and subsequent evolution around the Caribbean has made them the subject of much research. In many respects they are comparable to Darwin’s finches on the Galapagos Islands and the honeycreepers of the Hawaiian Islands. They diversified into more than 300 species by adapting morphologically and behaviorally to a variety of niches. The brown anole itself has been used as a model for understanding ecology, animal behavior, and evolution. Recent work with brown anoles observed natural selection in action.

emerge in June. Recent hatchlings are 0.6–0.7 in. (15–18 mm) long, SVL. Both males and females mature the following summer, and most die during the subsequent winter when about 18 months old. Impacts. The spread of the nonnative brown anole often appears to coincide with the decline of the native green anole, but much of the evidence is anecdotal. It has been demonstrated, however, that where the two species coexist, the green anole shifts its spatial niche higher into the canopy of trees and seldom utilizes ground perches. When the brown anole is absent, the green anole is a ground-trunk species. To what degree predation by brown anoles on green anole hatchlings affects populations of the latter is unknown. In places where the brown anole thrives, it can become the most numerous reptile in the area. Indeed, it is now one of the most abundant lizards, and possibly the most abundant vertebrate, throughout Florida. Management. No attempts to control or eradicate brown anoles have been made. Any measures taken would likely prove fruitless since the lizard is so prolific and such a generalist.

Selected References “Brown Anole.” Lizards of Georgia and South Carolina, Savannah River Ecology Laboratory, Herpetology Program, University of Georgia, n.d. http://www.uga.edu/srelherp/lizards/ anosag.htm. Campbell, T. “The Brown Anole (Anolis sagrei Dumeril and Bibron 1837).” Institute for Biological Invasions: The Invader of the Month, February 2001. University of Tennessee, Knoxville, 2002. http://invasions.bio.utk.edu/invaders/sagrei.html. Casanova, L. “Norops sagrei” Animal Diversity Web, University of Michigan Museum of Zoology, 2004. http://animaldiversity.ummz.umich.edu/site/accounts/information/Norops_sagrei.html. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Norops sagrei (reptile).” ISSG Global Invasive Species Database, 2006. http://www.issg.org/ database/species/ecology.asp?si=603&fr=1&sts=&lang=EN.

n Burmese Python Scientific name: Python molurus bivittatus Family: Boidae Native Range. Southern Asia. Found from northeastern India and Bangladesh, through Myanmar, Thailand, Laos, Cambodia, and Vietnam, into southern China. Also a number

218 n VERTEBRATES (REPTILES) of isolated populations in Nepal; Sichuan, China; and Java, Bali, and Sumbawa, Indonesia, that may represent relics of a formerly much larger distribution area or may represent introductions by humans. Distribution in the United States. Established in southern Florida, including Everglades National Park and Big Cypress Preserve, and also in Puerto Rico. They can be found outside Everglades National Park along its eastern boundary and increasingly in more distant areas, such as Collier-Seminole State Park and Manatee County. Several individuals have been observed on Key Largo, but at the moment, they do not seem to be established in the Florida Keys. Description. One of the world’s largest snakes, the Burmese python may grow to lengths greater than 25 ft. (7.6 m) and weights close to 300 lbs. (137 kg). The largest found to date in the Everglades was 16 ft. (4.8 m) long and Top: The native range of the Burmese python extends from northeastern weighed 152 lbs. (69 kg). India through Southeast Asia into southern China. (Adapted from Barker Females become longer and and Barker 2008.) Bottom: Burmese pythons are invasive in southern heavier than the males, which Florida, including Everglades National Park and Big Cypress Preserve. are distinguished by their larger They are also established on Puerto Rico. (Adapted from USGS 2007.) cloacal spurs, the two projections on either side of the vent that may be vestigial hind limbs. The light-colored skin of this heavy-bodied snake is beautifully marked with a mosaic of large reddish-brown blotches that are outlined in black. The pattern begins on the large rectangular head as an arrow-shaped patch. The pet trade has bred a number of variations, including albino, that may be found in wild Florida populations, since they all stem from released or escaped pets. Burmese pythons are semiaquatic but also climb trees. Related or Similar Species. Two large native pit vipers might be mistaken for young pythons. The eastern diamondback rattlesnake (Crotalus adamanteus) is also heavy-bodied and reaches lengths up to 7 ft. (2.1 m), but its head is triangular and the yellow-andbrown diamond pattern down its back is distinctive. Some Florida cottonmouths (Agkistrodon piscivorus) have a brown-and-black banded pattern and may reach lengths of

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A. The Burmese python, one of the world’s largest snakes, is beautifully marked with large reddish-brown blotches outlined in black. (Vassil.) B. The arrow-shaped patch on its squarish head is charactersitic. (Vassil.)

6 ft. (1.8 m). However, this snake has a triangular head and a dark cheek stripe that runs through the eye. Both of the pit vipers are venomous. Another brightly patterned snake that could be confused with a small python is a colubrid and a constrictor, the corn or red rat snake (Elaphe guttata guttata). It is common in residential areas and can reach lengths of 6 ft. (1.8 m). It has a spear- or arrow-shaped pattern on the head. Typically, the body is orange-brown with red or brown blotches outlined in black. The belly is marked with a black-and-white checkerboard, and two black stripes appear on the underside of the tail. Introduction History. Burmese pythons were first collected from the wild in southern Florida in the 1980s. They were first deemed established in Everglades National Park in 2000 based on collections made along Main Park Road in the 1990s. Since then, the number of pythons in the park has increased dramatically and is now estimated to be 10,000 or more. The first python in the Florida Keys was documented in 2007 at Key Largo Hammock Botanical State Park. Pythons are well able to the swim the six miles from the Everglades to Key Largo. Burmese pythons in Florida derive from the pet trade. They were either intentionally or accidentally released by pet owners. Burmese python hatchlings continue to be imported into the United States from Southeast Asia by the thousands, and domestic breeding of different color morphs also continues. Habitat. Burmese pythons can live in a variety of open habitats such as swamps, marshes, grasslands, and woodlands, including the brackish glades and mangroves at the south end of the Everglades. In Florida, they generally inhabit the same places that alligators do. These excellent swimmers are usually close to water, which they must enter before shedding, and can stay underwater without breathing for as long as 30 minutes. Diet. The Burmese python is a carnivore that prefers live prey but will consume carrion. Rodents and other small mammals are dietary staples, but it also takes amphibians, reptiles, and birds. Researchers in Florida have found alligators, limpkins, ibises, coots, House Wrens, rabbits, squirrels, mice and rats, muskrats, raccoons, Virginia opossums, bobcat, and white-tailed deer, as well as domestic cats and geese, in the digestive tracts of pythons captured in the wild.

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Other Big Snakes in Florida

T

he Burmese python is perhaps the most publicized invasive snake established in Florida; however, it is not the only giant snake on the loose. A population of boa constrictors (Boa constrictor) inhabits a county park and possibly adjacent areas in southeastern Miami. (It is difficult to know if individuals found beyond the park are dispersers from the park population or recently released or escaped pets.) In 2010, researchers reported establishment of another large constrictor, the Northern African python (Python sebae), in a small area southeast the Tamiami Trail at State Route 997. Other constrictors with free-living individuals in Florida, but apparently not reproducing populations, include the green anaconda (Eunectes murinus), the yellow anaconda (E. notaeus), the reticulated python (Broghammerus reticulates) and the white-lipped python (Leiopython albertisii). Sources: Reed, R. N., K. L. Krysko, R. W. Snow, and G. H. Rodda. “Is the Northern African Python (Python sebae) established in southern Florida?” IRCF Reptiles & Amphibians 17(1): 52–54, 2010. “Northern African Python, African Rock Python [Non-Native],” Florida Museum of Natural History, http://www.flmnh.ufl.edu/herpetology/fl-guide/Pythonsebae.htm.

The python has poor eyesight and hunts by using its sense of smell. It also has heating sensing pits along the upper lip with which it detects the body heat of its prey. It may either stalk or ambush its victims. Prey items are killed by constriction and swallowed whole. Life History. Burmese pythons are solitary except when they come together to mate between December and April. Then groups of one female and several males often form. Males locate the females chemically, detecting the pheromones secreted by the female. The male wraps himself around the female’s body and internal fertilization takes place. Two to three months later, in May and June, the female lays a clutch of 12–36 eggs (up to 100), each weighing about 7 oz. (200 g). She incubates the eggs for two months by coiling on top of them. The mother rarely if ever leaves her eggs and will raise their temperature above ambient temperature by shivering. The eggs hatch 2–3 months later, in July and August, and parental care ends. The hatchlings are 18–24 inches long and grow rapidly if food is abundant. Both males and females are sexually mature in 2–3 years and at lengths of about 8 ft. (2.6 m). Average lifespan is 15–25 years. Impacts. Burmese pythons have been in Florida’s Everglades too brief a time for definitive assessments of their impacts. The concern is that they will compete with native species and further endanger rare species upon which they prey. Among their known prey are two wading birds of special concern, the Limpkin (Aramus guarauna) and White Ibis (Endocemus albus). On Key Largo, prey included the endangered Key Largo woodrat (Neotoma floridana smalli). They may also may be preying upon native mangrove fox squirrels (Sciurus niger avicennia) and Wood Storks (Mycteria americana). Due to an overlap in diet, they could compete with the state and federally threatened eastern indigo snake (Drymarchon couperi) for food and space. With the population explosion that pythons in the Everglades are currently experiencing, they could become a major ecological problem and hamper efforts to restore the greater

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Everglades ecosystem. Their future establishment is a major concern in the biologically sensitive Florida Keys. Pythons pose a threat to small children and pets in residential areas and to small livestock and poultry in agricultural areas. Management. Once pythons are established, it becomes impossible to eradicate them. Efforts therefore focus on controlling numbers and preventing new infestations. The main strategy involves tracking, capturing, and euthanizing. In southern Florida, volunteer members of an Eyes & Ears Team spot pythons on roads and call in a person trained to capture and dispose of them. Among the people trained to find snakes are mail carriers and package delivery drivers who daily drive the region’s roads. In March and April 2010, a special python hunting season was instituted in Florida. Permit holders could also take African pythons and Nile monitors in this effort to kill as many large exotic reptiles as possible. Research continues to learn the ways of the python and monitor its spread. Recent legislation in Florida requires owners of pythons and some other large introduced reptiles to buy a permit and implant a microchip in the animal to identify its owner. A federal bill, the Non-native Wildlife Invasion Prevention Act (H.R. 669) that came before the Congress in 2009–2010, would prohibit the importation of species determined by the U.S. Fish and Wildlife Service to likely become invasive in the United States.

Selected References Austin, Jill. “Stopping a Burmese Python Invasion.” The Nature Conservancy, 2009. http:// www.nature.org/wherewework/northamerica/states/florida/science/art24101.html. Barker, David G., and Tracy M. Barker. “The Distribution of the Burmese Python, Python molurus bivittatus.” Bulletin Chicago Herpetological Society 43(3): 33–38, 2008. Available online at http:// www.vpi.com/sites/vpi.com/files/Barkers.pdf. Harvey, Rebecca G., Matthew L. Brien, Michael S. Cherkiss, Michael Dorcas, Mike Rochford, Ray W. Snow, and Frank J. Mazzotti. “Burmese Pythons in South Florida: Scientific Support for Invasive Species Management.” Publication #WEC242, IFAS Extension, University of Florida, 2008. ttp:// edis.ifas.ufl.edu/pdffiles/UW/UW28600.pdf. National Biological Information Infrastructure (NBII), Puerto Rico Department of Natural and Environmental Resources, and IUCN SSC Invasive Species Specialist Group (ISSG). “Python molurus bivittatus (Reptile).” ISSG Global Invasive Species Database, 2010. http://www.issg.org/database/ species/ecology.asp?si=1207&fr=1&sts. Padgett, J. “Python molurus.” Animal Diversity Web, University of Michigan, 2003. http:// animaldiversity.ummz.umich.edu/site/accounts/information/Python_molurus.html. “Python molurus bivittatus.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2009. Revised October 24, 2007. http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=2552.

n Green Iguana Also known as: Common iguana, gallina de palo Scientific name: Iguana iguana Family: Iguanidae Native Range. Mexico south through Central America to Ecuador on the Pacific side and southeastern Brazil on the Atlantic slope of South America. Also in the Lesser Antilles (Curacao, Grenada, St. Lucia, St. Vincent, Trinidad and Tobago, and Utila). Most iguanas imported as pets into the United States come from captive farming operations in Honduras, El Salvador, Colombia, and Panama.

222 n VERTEBRATES (REPTILES) Distribution in the United States. Established in southern Florida. Feral populations are also established on Maui, Hawai’i; in the Rio Grande Valley, Texas; on Puerto Rico; and on the U.S. Virgin Islands. Description. The green iguana is one of the largest lizards found in the United States. Only young animals are bright green; adults assume a uniform, grayish-green color, which they can alter somewhat in response to social and environmental cues. A month or so before courtship begins, the males acquire a bright orange wash on the neck and forelimbs that persists through the mating period. Color may also change diurnally, becoming darker when the body is cold so as to absorb more solar energy. A crest of large spines along the back and tail is particularly well developed on males, as is the very large dewlap under the throat. The fleshy dewlap is used in threat and courtship displays, but also helps absorb Top: Green iguanas are native to southern Mexico, Central America, and and dissipate heat. The tail is tropical South America. They also are native to the Lesser Antilles. long and tapering, and ringed (Adapted from “Green Iguana,” The Wild Ones Animal Index, http:// with broad dark stripes. The www.thewildones.org/Animals/iguana.html.) Bottom: Released or tympanum is prominent and escaped pets, green iguanas have established populations in southern covered by a membrane. Large Florida, on Mau’i in Hawai’i, in the Rio Grande Valley of Texas, and on scales appear on both sides of Puerto Rico. the head; beneath the tympanum is a large rounded scale known as a subtympanic plate. The eyes are set on the sides of the head and covered by an immobile upper lid and a movable lower lid. On the midline of the top of the head is a white, light-sensing organ known as the parietal “eye.” It helps coordinate photoperiod with reproductive status, but also detects the shadows of overhead predators. Sharp teeth are positioned along the inner sides of both jaws. Nasal glands help expel excess salts. Adult males may achieve a total length of 6 ft. (1.8 m) and weight of as much as 17.5 lbs. (8 kg), although 9–12 lbs. (4–6 kg) is more common in Florida specimens. Related or Similar Species. Some other large introduced lizards might be mistaken for young green iguanas. The black spinytail iguana (Ctenosaura similis) also has a crest of spines

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along the back, but has black banding on the body. Spiny scales circle around the tail. The young are bright green like young green iguanas, but have broken bands of black around the mid-body. The largest of these lizards may be 3–4 ft. (approximately 1 m) in total length. The brown basilisk (Basiliscus vittatus) has a large crest behind the head and a brown body; it only grows up to 2 ft. (60 cm) long. Knight anoles (Anolis equestris) and Jamaican giant anoles (A. garmani), are both green but only about 1 ft. (30 cm) long. Introduction History. Baby green iguanas are imported into Florida by the tens of thousands each year in the pet trade. They were first reported outside captivity in the Miami area in 1966, but populations probably did not become established until the 1980s, when they became popular pets. Mature green iguanas become powerful animals that can bite, scratch, and whiplash owners with their tails. When they become too much to handle, they are often released into the wild. The earliest sightings of free-living iguanas were in Key Biscayne, Hialeah, and Coral Gables, and in the vicinity of Miami International Airport. Undoubtedly, these reptiles were intentional releases by pet owners or accidental escapes. Since that time, they have expanded northward on the Atlantic coast, establishing populations in Broward County by 2001 and in Palm Beach County by 2003. Along the Gulf coast, iguanas were reported as established in Monroe County (Coral Reef State Park) in 1995 and in Lee County (Fort Myers and Cape Coral) sometime in the 1990s. Increasing numbers are seen in Martin and St. Lucie counties, but the iguana does not yet seem to be established in those areas. Iguanas have also been reported in Pinellas County on the Gulf coast. Expansion much farther north seems to be halted by irregular freezes. Green iguanas are relatively common in the Everglades, and individuals have been reported as far south in the Keys as Stock Island. Habitat. In Florida, the green iguana occurs in frost-free coastal areas. They thrive only where temperatures range from 79° to 95°F (24–32°C) and where sunlight is sufficient to let their bodies produce vitamin D. They are mostly arboreal and prefer large trees overhanging water, into which they dive to escape predators. Therefore, they are likely to be near canals, ditches, and ponds, and in mangroves lining the shores of shallow bays. Iguanas also inhabit urban and suburban yards and like to bask on tree branches, sidewalks, docks, and seawalls, or in open, mowed areas. Diet. Green iguanas are herbivores and feed on leaves, flowers, and fruits. Juveniles consume insects and other animal matter in addition to plant foods. Digestion occurs in the hindgut, and juveniles eat the droppings of adults in order to acquire the microflora necessary to break down plant material. Among preferred food plants are hibiscus, orchids, roses, garden greens, and squashes and melons. Life History. Green iguanas breed during the dry season so that the young hatch during the wet season when food will be most plentiful. Iguanas of both sexes come together in sandy areas to mate during a single nesting season each year. Dominant males scent-mark territories and females with pheromones secreted from femoral pores on the undersides of their thighs. Fertilization is internal. About 65 days after mating, each female excavates a burrow 1.5–3 ft. (0.5–1.0 m) deep and, over a period of three days, deposits 20–70 eggs in it. If nesting space is scarce, several females will use the same nest. No parental care is given to the nest or eggs. Eggs measure roughly 0.6 in. (15 mm) in diameter and 1.5 in. (35–40 mm) long. Hatchlings emerge 10–15 weeks later, usually during July and August, and look like miniature females without spiny crests. They are 6.5–10 in. (17–25 cm) in total length. The juveniles remain in family groups for a year; curiously, the young males protect the females from predators. Green iguanas become sexually mature at 3–4 years of age. The reproductive life of a female lasts several years. After mating, she is able to store sperm for several years and fertilize her eggs even if a male is not present.

224 n VERTEBRATES (REPTILES)

A. The green iguana has a crest of long spines and a very large dewlap. (Susan Woodward.) B. This large lizard has a long tail ringed with dark bands and a prominent external ear drum. (Susan Woodward.)

Impacts. Threats to native lizards are probably slight, since adult green iguanas are herbivores and all native species are carnivores. Green iguanas sometimes use the burrows of the Florida Burrowing Owl (Athene cunicularia floridana), a federally endangered subspecies, and could prevent the birds from nesting or destroy their eggs and nestlings. Iguanas eat the native butterfly sage (Cordia globosa), a plant of special concern in Florida, and consume yellow nickerbean (Caesalpinia bonduc), a primary host for the larvae of the endemic and endangered Miami blue butterfly (Hemiargus [=Cyclargus] thomasi bethunebakeri). They are potential dispersers of any invasive plants upon which they feed. In residential areas, iguanas can destroy vegetable gardens and ornamental plants and pose a health hazard by spreading salmonellosis when they defecate in pools or on docks and sidewalks. Their droppings are also unsightly and smelly. In Puerto Rico, basking green iguanas are a runway hazard at the Luis Mun˜oz Marı´n International Airport and must be shooed away before planes can take off.

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Management. Iguanas can be removed from private property without special permits. They can be caught legally in Florida by hand, noose pole, nets, or live traps. It is illegal, however, to release captured animals; so they must be kept as pets or captive breeding stock or be destroyed. Feral adults rarely tame down. The best control measures are to discourage iguanas by removing protective cover from the yard, sheathing trees with metal to prevent their climbing up to sun bathe, not planting their favorite food plants, and protecting valued plants in screened enclosures. In open country, it is very difficult to capture iguanas because they are such strong swimmers and dive into water at the first sign of danger. Sometimes in cold weather, when they are sluggish, they can be picked off branches or off the ground. Local iguana populations along canals and in mangroves have been reduced using boats to collect those knocked off branches when temperatures are in the 40s. In Florida, iguanas are protected only by anticruelty laws. In Hawai’i, strict laws regulate the importation and possession of green iguana, and violations can lead to fines of $200,000 and up to three years in jail.

Selected References Gibbons, Whit, Judy Greene, and Tony Mills. Lizards and Crocodilians of the Southeast. Athens: University of Georgia Press, 2009. Gingell, F., Biology of Amphibians and Reptiles, and J. Harding. “Iguana iguana” Animal Diversity Web, University of Michigan Museum of Zoology, 2005. http://animaldiversity.ummz.umich.edu/site/ accounts/information/Iguana_iguana.html. “Green Iguana.” Wikipedia, 2009. http://en.wikipedia.org/wiki/Green_Iguana. “Green Iguana—Iguana iguana.” Florida’s Exotic Wildlife. Species detail. MyFWC.com, Florida Fish and Wildlife Conservation Commission, n.d. http://myfwc.com/wildlifehabitats/nonnatives/ reptiles/green-iguana/. Kern, W. H., Jr. “Dealing with Iguanas in the South Florida Landscape.” Publication #ENY-714, IFAS Extension, Univeristy of Florida, 2009. http://edis.ifas.ufl.edu/in528. Masterson, J. “Iguana iguana: Green iguana.” Smithsonian Marine Station at Fort Pierce, 2007. http:// www.sms.si.edu/irlspec/Iguana_iguana.htm. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive species Specialist Group (ISSG). “Iguana iguana (Reptile).” ISSG Global Invasive Species Database, 2006. http:// www.invasivespecies.net/database/species/ecology.asp?si=1022&fr=1&sts.

n Nile Monitor Also known as: Money monitor Scientific name: Varanus niloticus Family: Varanidae Native Range. Much of Africa between 15° N and 15° S. It occurs in forests and savannas near permanent water. It is absent from desert regions, but has been found at elevations greater than 6,500 ft. (2,000 m). Distribution in the United States. Known to be established in at least two counties in southern Florida: Lee County (Cape Coral) and adjacent Charlotte County. Sightings of Nile monitors are reported from several other counties, including Broward, Collier, DeSoto, Miami-Dade, Orange, and Palm Beach. Description. This is the largest lizard now occurring outside of captivity in the United States and the longest lizard in its native Africa. Nile monitors can reach SVLs averaging

226 n VERTEBRATES (REPTILES) 23.5–31.5 in. (60–80 cm) and total lengths over 7.5 ft. (2.4 m). They may weigh more than 22 lbs. (10 kg). Like all monitors, they have long necks, long tails, and an obviously forked tongue. The head is narrow and wedgelike and shorter than the neck. The tongue is blue. The background color is gray-brown or olive green. The jaws and head bear cream-colored stripes that graduate into chevrons on the neck. Six to nine bands of yellow dots encircle the body. Said to look like coins, these dots are the origin of one of the African names for this species, the “money monitor.” Juveniles are more brightly patterned than adults. Nile monitors have large, strong claws for digging and a muscular tail that is laterally compressed for swimming and usually 1.5 times as long as the body. Related or Similar Species. The Asian water monitor (Varanus salvator) looks a bit like the Nile monitor and grows even longer, reaching lengths of 10 ft. (3 m). It lacks the bands Top: The Nile monitor is native to forests and savannas in much of Africa. of “coins” adorning the Nile (Adapted from map at http://en.wikipedia.org/wiki/File:Nile_monitor_ monitor. As far as it is known, range.PNG.) Bottom: The Nile monitor is established in at least two water monitors are not living counties in southern Florida and has been reported from several others. free in Florida, but they are (Adapted from Somma 2007.) easily obtained through the pet trade, and it is entirely possible that they will become established in the state. Some reported observations of individual Nile monitors may actually have been escaped or released water monitors. Introduction History. Free-living Nile monitors were first spotted at Cape Coral in 1990. Their origins are unknown but presumed to be related to the pet trade. One rumor has it that a pet store that went bankrupt in the 1980s released their Nile monitors into what was then a wilderness of saw palmettos, slash pine, and mangrove. Another story suggests that wholesalers of exotic animals purposefully released monitors to establish a breeding population from which they could capture young animals to sell. It is perhaps most likely that the animals came from pet owners who found that the cute little hatchlings they had purchased had turned into large, temperamental reptiles they no longer wanted or could manage, so they “humanely” released them. The animals are also quite able to escape from

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cages on their own. As the cape was developed, monitors came into more frequent contact with residents and the number of observations increased, especially along canals in the western part of the peninsula. By 2002, monitors had crossed Matlacha Pass onto Pine Island. Sanibel Island to the south lies within reach. Since some populations in Africa are adapted to temperate climate, monitors from those regions, if introduced to the United States, theoretically could spread throughout Florida and the Gulf states and possibly as The Nile monitor has a narrow wedge-shaped head and a laterally comfar north as the Carolinas. Habitat. Nile monitors are pressed tail for swimming. (Dr. Gordon E. Robertson.) well adapted to both terrestrial and aquatic habitats. They prefer cover near permanent bodies of water. In Florida, favorable conditions exist in mangrove swamps, along the edges of both freshwater and saltwater marshes, and on the banks of rivers and canals. In Lee County, they also live in pine flatwoods, on golf courses with ponds, and in suburban neighborhoods and urbanized areas. They shelter in burrows that they dig into canal banks or in those excavated by other animals. In Africa, they live in a variety of climates at different elevations and will hibernate during cold weather in more temperate regions. Diet. Nile monitors are indiscriminate carnivores and scavengers. They will consume invertebrates such as cockroaches, mangrove tree crabs, snails, and clams; amphibians, including the introduced Cuban treefrog (see Amphibians, Cuban Treefrog); lizards, snakes, baby alligators, and turtles, as well as the eggs of reptiles; birds and bird eggs; and small mammals such as rodents and cats. They also eat carrion, garbage, and feces. Young monitors are more arboreal than mature adults and feed almost exclusively on fast-moving invertebrates and lizards. With increasing age, they consume less active prey that is more armored and must be crushed by strong jaws and teeth before being swallowed. These intelligent animals will hunt cooperatively. Life History. What information is available on life history comes from studies done in the monitor’s native habitats in Africa and may or may not be directly applicable to populations in Florida. In the Sahel region of Africa, females are sexually mature when they are two years old and have a SVL of about 14 in. (36 cm). They breed every other year, so during any given breeding season, only 50 percent of adult females lay eggs. In some areas, females feed and accumulate fat in spring and summer. Eggs are laid during the winter dry season, buried in the ground and in active termite mounds. Clutches average 35 eggs or more, with smaller females producing many fewer than larger ones. Each egg is about 3.5 × 1.6 in. (6 × 4 cm). Hatchlings emerge 6–10 months later, near the beginning of the wet season. They are 6–12 in. (15–32 cm) in total length and will more than double in size during the first year of life. Nile monitors can live more than 10 years in the wild. Impacts. Nile monitors are potentially the most destructive lizard introduced to Florida. Nile monitors in Lee County, Florida, could have negative effects on native crocodilians,

228 n VERTEBRATES (BIRDS) (the American alligator [Alligator mississippiensis] and, especially, the American crocodile [Crocodylus acutus]), for in Africa, Nile monitors not only have diets similar to those of crocodiles, but also are the major predators of crocodilian eggs and hatchlings. Their propensity to occupy existing burrows raises concern for two protected species on the Cape Coral peninsula, the Burrowing Owl (Athene cunicularia) and the gopher tortoise (Gopherus polyphemus), whose nesting burrows could be taken over and eggs and young consumed. If Nile monitors were to invade Sanibel Island, the large rookeries of pelicans and herons would be threatened. If they gain access to Sanibel’s beaches, the nests of sea turtles would be vulnerable to their depredations. Should Nile monitors make their way into southeastern Florida and the Keys, a number of listed species could become prey, including the southeastern beach mouse (Peromyscus polionotus niveiventris), Key Largo cotton mouse (Peromyscus gossypinus allapaticola), Key Largo woodrat (Neotoma floridana smalli), and silver rice rat (Oryzomys palustris argentatus). When cornered, Nile monitors become very defensive and attack with their teeth, sharp claws, and strong tails. Humans and pets are at risk of serious wounds that can become septic due to the bacteria in monitors’ mouths. Small dogs and domestic cats are also at risk since they can be caught easily and eaten by monitors. Reports from Cape Coral suggest a decline in pet populations as the monitor population increased. Management. Once established, Nile monitors are very difficult if not impossible to eradicate. Population reduction and prevention of further infestation are the main management strategies. Monitors may be captured with nooses or live traps or by digging them out of the ground. Arboreal hatchlings can be caught at night by hand. Regulations can keep monitors from being purchased in the first place by casual, untrained pet owners.

Selected References Enge, K. M., K. L. Krysko, K. R. Hankins, T. S. Campbell, and F. W. King. “Status of the Nile Monitor (Varanus niloticus) in Southwestern Florida.” Southeastern Naturalist 3(4): 571–82, 2004. Gore, Jeff, Kevin Enge, and Paul Moler. “Nile Monitor (Varanus niloticus) Bioprofile.” MyFWC.com, Florida Fish and Wildlife Conservation Commission, n.d. http://www.scribd.com/doc/26904049/ NILE-MONITOR-Varanus-Niloticus-Bioprofile-Compiled-By. Kruse, Michael. “Nile Monitor Lizards Invaded Florida and They’re Winning the Battle.” St. Petersburg Times, June 21, 2009. Available online at http://www.tampabay.com/news/environment/wildlife/ article1011745.ece. “Nile Monitor.” Florida’s Exotic Wildlife, MyFWC.om, Florida Fish and Wildlife Conservation Commission, Tallahassee, 2007. http://myfwc.com/wildlifehabitats/nonnatives/reptiles/nile-monitor/. Somma, Louis A. “Varanus niloticus.” USGS Nonindigenous Aquatic Species Database, Gainesville, FL, 2009. Revised August 28, 2007. http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=1085. Youth, Howard. “Florida’s Creeping Crawlers.” ZooGoer 34(3), Smithsonian National Zoological Park, 2005. http://nationalzoo.si.edu/Publications/ZooGoer/2005/3/reptilefeature.cfm.

n Birds n Cattle Egret Also known as: Buff-backed Heron Bubulcus ibis Family: Ardeidae Native Range. Parts of Africa and Asia and southern Spain and Portugal.

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Distribution in the United States. This bird has been reported in all states, but breeding takes place primarily in the southeastern United States as far north as Virginia in the east and Kansas in the center of the country. Resident populations can also be found in southernmost California, Hawai’i, and Puerto Rico. Description. The Cattle Egret is a small white heron about 20 in. (46–56 cm) long with a wingspan of about 36 in. (88–96 cm). It is stocky and has a thick neck, shorter than its body length. When standing still, it typically assumes a hunched position. Most of the year its plumage is white, but for a short time during the mating season, orange-buff feathers occur on the crown, throat, and back. The bill is relatively short and yellow, and the legs yellow to gray-green during the non-breeding season, but both turn red during the breeding season. In flight, the Cattle Egret holds its neck tight to the body. Top: The Cattle Egret’s vast native range spans much of non-desert Africa, Cattle Egrets are gregarious and the southern Iberian peninsula of Europe, and South and Southeast Asia. fly to and from feeding areas in (Adapted from map at http://wapedia.mobi/en/File:Ardea_ibis_map.svg.) flocks. When it walks, it tends Bottom: Cattle Egrets can be found in all states, but breeding populations to sway in an exaggerated strut occur primarily in the southeastern states, southern California, Hawai’i, and then suddenly dart forward and Puerto Rico. (Adapted from map by Cornell Lab of Ornithology. http://www.allaboutbirds.org/guide/Cattle_Egret/lifehistory.) to stab its prey. Most often, Cattle Egrets forage alongside grazing animals, waiting for the livestock to flush insects. They may also pick parasites off large herbivores and be seen standing on the animals’ backs. Cattle Egrets are usually silent. Their voice consists of a low, nasal “rik-rak.” Related or Similar Species. The Cattle Egret is smaller than any native herons or egrets that have white plumage. It might be confused with the somewhat taller Snowy Egrets (Egretta thula) and juvenile Little Blue Herons (Egretta caerulea). Snowy Egrets are distinguished by their black legs and yellow feet, as well as a black bill. They are adorned with long, lacy white plumes on the neck and back during the breeding season. Juvenile Little Blue Herons have dull, greenish legs and a pale gray or greenish bill. Both of these birds

230 n VERTEBRATES (BIRDS)

A. The Cattle Egret is a small, stocky heron. (Robbie Taylor/Shutterstock.) B. Cattle Egrets commonly hunt insects flushed by cattle or other large mammals. (Donna Beeler/Shutterstock.)

are associated with freshwater, where they feed on fish and aquatic invertebrates; whereas the Cattle Egret is generally found in upland pastures and feeds mostly on insects. Introduction History. The introduction of the Cattle Egret to the Americas appears to have been a natural event. It suddenly arrived in Suriname, South America, in the late 1870s and 1880s, presumably having simply flown across the Atlantic Ocean from the African continent. It spread throughout South America, filling a vacant niche as a unique terrestrial member of the heron family. By 1917, it was in Colombia, and in the 1940s, it showed up in Florida. In the United States, its long-distance wandering habits let it rapidly expand its range. By the 1960s, it was in California as well as Canada. In contrast to the natural range expansion that carried the Cattle Egret to all of the continental United States, the bird was deliberately introduced to Hawai’i in 1959. Local ranchers funded efforts by the Hawaiian State Board of Agriculture and Forestry to establish Cattle Egrets as a biological control for flies and other insects that were cattle pests. Twentyfive egrets were released at Kipu Ranch on Kaua’i, and 105 others were distributed among ranches on Hawai’i, Maui, Moloka’i, and O’ahu. The Honolulu Zoo also received some birds. The egrets began nesting soon after release and established large populations on Kaua’i and O’ahu, where they came to attain pest status. Habitat. Cattle Egrets commonly inhabit pastures, marshes, and ploughed fields. They thrive in altered habitats and tolerate busy roadsides and urbanized areas well. Most often, when feeding, they associate with cattle or other livestock. Cattle Egret roosts are usually

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in trees or shrubs near water. They are colonial nesters and frequently nest in dense rookeries with other herons and egrets. Diet. Insects are the mainstay of the Cattle Egret diet. They consume live insects flushed by grazing mammals, but are also known to follow tractors, plows, lawn mowers, and even airplanes to snatch insects disturbed by the machines. Most of their food consists of grasshoppers, crickets, flies, and beetles, but when insects are not abundant, they will take spiders, certain moths, frogs, and crayfish as well as bird eggs and nestlings. They also scavenge in refuse for edible leftovers. Life History. Males establish breeding territories within large colonial nesting areas from spring through early summer. Courtship displays attract females, and pair-bonds are established that last the season. Bulky nests of sticks are built by the female from materials carried to her by the male. Nest-building and mating commonly last only three days. The breeding colors are lost as soon as mating is over. When egg-laying begins, one pale blue egg is produced every other day. The eggs are not brooded until the last egg is laid. Clutches usually consist of 34 eggs. Both adults incubate the eggs for approximately 24 days. The eggs hatch in the order in which they were laid; usually only the first two survive to fledge. The siblings begin to compete with each other for food when less than a week old. Two to three weeks after hatching, they leave the nest to climb around the rookery but continue to beg for food from the parents. They begin to fly a week or so later and become independent about 2.5 months after hatching. Juveniles disperse hundreds of miles in apparently random directions. Even as adults, the egrets are highly migratory and wander widely. Cattle Egrets become members of the breeding population at 2–3 years of age. Impacts. In most instances, Cattle Egrets have little or no impact on native heron species. They utilize different habitats for feeding, have a different diet, and breed after the nesting seasons of native birds. Some concern does remain that they could potentially displace native herons and egrets in rookeries, since they occur in such large numbers. Cattle Egrets are now more numerous in North America than all other herons and egrets combined. In Hawai’i, the birds are not quite as benign as on the mainland. They are known to feed on the eggs and young of endangered wetland birds such as the Black-necked Stilt or A’eo (Himantropus mexicanus) and could compete with such insect-eating species as frogs, toads, and skinks. Furthermore, they have become a nuisance for aquaculture on Oahu because they feed on prawns and are a hazard at airports in Honolulu, Lihue, and Hilo. Large rookeries anywhere can become nuisances due to noise, odor, and potential public health threats. Management. Population reduction and control efforts in Hawai’i are likely to have only temporary effects, since the birds are so mobile and will return to areas from which they have been removed. Techniques that repel Cattle Egrets may have some success at airports and nuisance rookeries. Elsewhere, the bird is usually not viewed as a problem and may even be welcomed as a way of helping to control insect pests of cattle.

Selected References Ivory, A. “Bubulcus ibis.” Animal Diversity Web, University of Michigan Museum of Zoology, 2000. http://animaldiversity.ummz.umich.edu/site/accounts/information/Bubulcus_ibis.html. Masterson, J. “Bubulcus ibis (Cattle Egret).” Species Report, Smithsonian Marine Station at Fort Pierce, 2007. http://www.sms.si.edu/irlspec/bubulcus_ibis.htm. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Bubulcus ibis (bird).” ISSG Global Invasive Species Database, 2006. http://www.issg.org/ database/species/ecology.asp?fr=1&si=970&sts.

232 n VERTEBRATES (BIRDS) “The Cattle Egret.” Hawaii Nature Focus, Booklet No. 10, Kilauea Point Natural History Association, n.d. http://www.kilaueapoint.org/education/naturefocus/hnf10/index.html.

n Common Myna Also known as: Indian Myna, House Myna Scientific name: Acridotheres tristis Family: Sturnidae Native Range. Southern Asia from southeastern Iran and Afghanistan through Pakistan, India, Nepal, and Sri Lanka to Southeast Asia and southern China. Distribution in the United States. Established on all the major islands of Hawai’i and in southern Florida. Description. This member of the starling family is a stocky brown bird with a glossy black head and neck, yellow bill, and yellow legs. A patch of bare yellow skin occurs behind the eye. Adults are 9.0–9.8 in. (23– 25 cm) long and have a wingspan of 18 in. (46 cm). In flight, the white tips of tail feathers and white wing patches are clearly visible. Immatures have duller colors and browner heads than adults. Common Mynas have a large repertoire of raucous calls, squeaks, clicks, and whistles. Both males and females sing and often fluff their feathers and bob their heads when vocalizing. At dawn and dusk they engage in loud choruses and at their communal roosts keep up a noisy chatter well after dark. Common Mynas strut across the ground, rather than hopping as many birds do. They tend to travel in pairs. Top: The native range of the Common Myna stretches across southern Related or Similar Species. Asia from southwest Iran to Vietnam. (Adapted from “Common Mynas Common Mynas are related to aka Indian Mynas aka Talking Mynas.” AvianWeb, 2006.) Bottom: the European Starling (see Common Mynas are established in southern Florida and on all the Birds, European Starling) and major islands of Hawai’i. (Adapted from “Common Myna Acridotheres share some of their annoying tristis” 2003.)

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behaviors. The Hill Myna (Gracula religiosa) is the more common pet talking myna. It is larger than the Common Myna and has a black body with fleshy yellow wattles on the head that extend back from below the eyes to the nape. The bill is red or orange. This mostly arboreal bird has escaped captivity and may be encountered in urban gardens and parks in Miami, Florida, and in several large cities in southern California and Hawai’i. Introduction History. The Common Myna was brought to Hawai’i from India in 1865 by Dr. William Hildebrand in an A bare patch of yellow skin behind the eye distinguishes the Common Myna. The white wing patch is more conspicuous in flight. (K. W. effort to control army worms Bridges, “Common Campus Birds,” University of Hawai’i at Manoa. http:// (Spodoptera mauritia) and army www.botany.hawaii.edu/biology101/birds/common_myna.htm) cutworms (Euxoa auxiliaris) that were devastating the islands’ sugar cane and pastures. They did help control cutworms, but also adapted well to urban life and were abundant in Honolulu by 1879. Eventually, they inhabited all the main islands. Common Mynas’ ability to “talk,” i.e., mimic human voices, and their general intelligence made them part of the pet trade. Mynas in Florida most likely derive from escapes or intentional releases of pet birds. The first sighting and confirmed breeding of the Common Myna in the state was in Miami in 1983. It has since been reported from 19 other counties within a 300-mi. (480 km) radius of that city and may have spread as far north as Sapelo Island, Georgia. Although the bird has dispersed rapidly, its numbers have not exploded, and small scattered populations seem to be the rule. Habitat. Common Mynas prefer open country such as farmland and suburban and urban parks and yards. The small populations in Florida apparently prefer shopping mall parking lots. In their native range, they inhabit open lowland woodlands and the edges of settlements and roost in isolated stands of tall trees. They are cavity nesters, but are not restricted to holes in trees, building their bulky nests in any nook or cranny available. Diet. Common Mynas are omnivorous. They take insects—especially grasshoppers, small vertebrates, and carrion, feeding mostly on the ground. Its generic name Acridotheres means “grasshopper hunter.” Mynas also feed on grains and fruits and sometimes on the eggs and nestlings of other bird species. In Florida, they are known to beg for French fries at fast food establishments. Life History. Common Mynas begin to build their nests of grass, leaves, and twigs in late February or early March. Both parents construct the nest, which may be placed in tree cavities, crevices in buildings, martin houses, and the tops of coconut and date palms, and aggressively defend their nesting territories. Between March and July, the female lays 2–5 blue eggs, and she and the male both incubate them. Chicks hatch in 13–18 days. They fledge when 3–4 weeks old. Parental care continues for another month while the young

234 n VERTEBRATES (BIRDS) learn to forage for themselves. A female may produce 1–3 clutches a year. Both sexes reach maturity at one year of age. Juveniles form small flocks once they become independent of their parents. Adults forage in loose groups of 5–6 birds. During the nonbreeding season, Common Mynas will roost together in huge flocks numbering more than 1,000 birds. Impacts. The noise and droppings from large flocks of Common Myna can make them a nuisance in urban and suburban settings. However, due to the large numbers of insects they consume and their bold antics, many people like this bird. In Hawai’i, they serve as a reservoir for avian malaria (see Microorganisms, Avian Malaria) and are thus implicated in the decline of endemic island birds. They disperse the seeds of lantana (Lantana camara; see Volume 2, Shrubs, Lantana)—which is an invasive weed in both Hawai’i and Florida—and prey upon the eggs and nestlings of native songbirds and seabirds such as the Wedge-tailed Shearwater (Puffinus pacificus). In Florida, they compete with Purple Martins for nest sites, but do not congregate in the large flocks typical elsewhere, so are not as problematic as in Hawai’i. The Common Myna has been introduced to many parts of the world, including many islands in the Pacific. It is such an agricultural pest in fruit- and wheat-growing areas (especially in Australia) that the IUCN has included the Common Myna on its nomination list for “100 of the World’s Worst invasive alien species.” Management. Although the Common Myna has not become the pest it has in other parts of the world, its importation into the United States is now prohibited.

Selected References “Common Myna Acridotheres tristis.” Florida’s Breeding Bird Atlas: A Collaborative Study of Florida’s Birdlife, 2003. http://legacy.myfwc.com/bba/docs/bba_COMY.pdf. “Common Myna—Acridotheres tristis.” Florida’s Nonnative Wildlife. Species detail. MyFWS.com, Florida Fish and Wildlife Conservation Commission, 2009. http://myfwc.com/wildlifehabitats/ nonnatives/birds/common-myrna/. “Common Mynas aka Indian Mynas aka Talking Mynas.” AvianWeb, 2006. http://www.avianweb.com/ commonmynas.html. IUCN/SSC Invasive Species Specialist Group (ISSG). “Acridotheres tristis (Bird).” ISSG Global Invasive Species Database, 2006. http://www.issg.org/database/species/ecology.asp?si=108&fr=1&sts. Lin, T., and T. Root. “Acridotheres tristis.” Animal Diversity Web, University of Michigan Museum of Zoology, 2007. http://animaldiversity.ummz.umich.edu/site/accounts/information/Acridotheres _tristis.html. Pranty, Bill. “Common Myna (Acridotheres tristis).” In Pranty, B., J. L. Dunn, S. C. Heinl, A. W. Kratter, P. E. Lehman, M. W. Lockwood, B. Mactavish, and K. J. Zimmer, “Annual Report of the ABA Checklist Committee: 2007–2008,” 37. Birding 40: 32–38, 2008. Available online at http:// www.aba.org/birding/v40n6p32.pdf. “The Common Myna.” Nature Focus Booklet #5. Kilauea Point Natural History Association, n.d. http:// www.kilaueapoint.org/education/naturefocus/hnf5/index.html.

n Eurasian Collared-Dove Scientific name: Streptopelia decaocto Family: Columbidae Native Range. South Asia. Prior to the 1600s, the native range was apparently restricted to India, Sri Lanka, and Myanmar. Its range later expanded by natural means and through deliberate introductions to Turkey and southeastern Europe, and by the end of the twentieth century, it was found throughout Europe.

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Distribution in the United States. Southeastern and central United States; Los Angeles region of California. The range is rapidly expanding, however, and it may soon be in all 49 continental states. Description. Like several native doves, the Eurasian Collared-Dove is a mediumsize bird with short legs and a small head. The body is pale gray with a slightly pinkish wash over the head and breast. The slender bill is black, the legs and feet are mauve, and the eyes are red. A black line forms a distinct “collar” on the back of the neck; above it is a white line. The square tail is white underneath. The sexes look alike. Adults are 12–13 in. (30–33 cm) long and have a wingspan of 18–22 in. (45– 55 cm). Average weight is 7 oz. (200 g). Juveniles are similar to adults except that their feathers have pale reddish edges and their eyes are brown. The legs are a darker brownish red. Until they are three months Top: The Eurasian Collared-Dove is native to South Asia. Prior to the old, they display no clear collar. 1600s, it seems to have been restricted to the area shown on the map, Eurasian Collared-Doves but since that time its range has expanded through Turkey to all of have a rhythmic “coo COOO Europe. Bottom: The range of the Eurasian Collared-Dove is rapidly cup” resembling that of the expanding in the United States. Currently found in southeastern and central states, it may eventually invade all of the continental United States. native Mourning Dove (Zenaida (Adapted from Sibley 2000.) macroura), but lower in pitch. During display flights, they produce a harsh, nasal “krreew” call. The wings do not whistle when the bird takes flight. Related or Similar Species. The native Mourning Dove is smaller and lighter and has a long pointed tail. When it takes flight, the wings produce a whistling sound. The native White-winged Dove (Zenaida asiatica) is about the same size as the Eurasian CollaredDove and has a square tail, but the tail is dark underneath with a white edge. Its white wing patch is distinct at rest and in flight. Neither native species has a black collar. Closely related and very similar in appearance to the Eurasian Collared-Dove is the somewhat smaller, introduced Ringed Turtle-Dove (Streptopelia risoria) for which it was initially mistaken. The turtle-dove is a feral bird of extremely limited distribution in the United States. It is

236 n VERTEBRATES (BIRDS) distinguished from the Eurasian Collared-Dove by its very light color and white tail and undertail coverts as well as its call. Introduction History. The Eurasian Collared-Dove came to the New World as a cage bird. It first became established in the wild in the Bahamas in 1974 when birds escaped from a breeder. They are excellent colonizers, as their history in Europe demonstrates; and by the 1980s, they had expanded their range into southern The Eurasian Collared-Dove is pale gray with a distinct black “collar” on Florida. By 2009, they were the back of the neck. (Gregg Williams/Shutterstock.) well established in the southeastern United States, especially along the Atlantic and Gulf coasts; isolated populations were established in the southern Plains states and southern Rocky Mountain states as well as in southern California. It has been reported in Alaska and in the Great Lakes region, but these may represent local escapes of captive birds. In some or the disjunct areas, the dove has been deliberately released for sport hunting or represents an accidental introduction. At least some of these populations are expected to serve as nuclei from which further range expansion will occur. Habitat. Eurasian Collared-Doves are most abundant in coastal, agricultural, and suburban habitats. They forage in open areas and tend to avoid forested areas and areas that are intensively cultivated. Nests are constructed in trees and shrubs and on man-made structures. Diet. These birds are primarily seed and fruit eaters, but also consume small invertebrates. They generally forage on the ground but will eat at bird feeders. Life History. Eurasian Collared-Doves are monogamous and have long breeding seasons; they may breed year-round in warm climates. In Florida, a pair may raise three or more broods each year. Each clutch consists of two eggs, the first laid being significantly larger than the second. Both parents incubate the eggs until they hatch about 15 days after laying. Hatching is asynchronous, with the second egg hatching 12–40 hours after the first. The young are fed regurgitated crop milk; as they get older, seeds become part of the nestlings’ diet. Juveniles fledge at about 18 days of age and are independent of the parents when 30–40 days old. The young are sexually mature by their first spring. In the nonbreeding season, the birds congregate at communal roosts. Eurasian CollaredDoves live a relatively long time; the oldest bird on record was more than 13 years old. Impacts. When they occur in large numbers, Eurasian Collared-Doves can deter other birds from using bird feeders and may even aggressively defend the food source. Large flocks also become a noise problem and produce large amounts of unsightly droppings. They can transmit the parasite Trichomonas gallinae to native doves using the same feeders or birdbaths and to hawks that prey upon them. Potentially, they could damage crops, but such impacts have not been reported. Management. Eradication is no longer a possibility. Numbers may be controlled by hunting. As an introduced species, it is not protected by law; but state and local hunting regulations still apply.

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Selected References Johnson, Steve A., and Gay Donaldson-Fortier. “Florida’s Introduced Birds: Eurasian Collared-Dove (Streptopelia decaocto).” Document WEC256, Department of Wildlife Ecology and Conservation, University of Florida/ Institute of Food and Agricultural Services, 2009. http://edis.ifas.ufl.edu/ uw301. National Biological Information Infrastrucutre, IUCN French Committee, and IUCN SSC Invasive Species Specialist Group. “Streptopelia decaocto (bird).” ISSG Global Invasive Species Database, 2008. http://www.issg.org/database/species/ecology.asp?si=1269&fr=1&sts=&lang=EN. Sibley, David Allen. “Eurasian Collared-Dove.” In National Audubon Society, The Sibley Guide to Birds, 256. New York: Alfred A. Knopf, Inc., 2000. Sibley, David Allen. “Ringed Turtle-Dove.” In National Audubon Society, The Sibley Guide to Birds, 256. New York: Alfred A. Knopf, Inc., 2000.

n European Starling Also known as: Common Starling Scientific name: Sturnus vulgaris Family: Sturnidae Native Range. Europe. In lowlands from the United Kingdom westward across Ukraine and Central Asia to western China. The Starling is a summer visitor in the northern part of its range where the climate is continental. Migratory birds winter in the Mediterranean region in Spain, Portugal, North Africa, and across the Middle East into Pakistan. Distribution in the United States. The European Starling is common in all of the contiguous 48 states and is also found in Hawai’i. In Alaska, resident populations occur around Anchorage and the Kenai Peninsula; breeding birds summer in the Yukon River valley. Description. European Starlings are robin-size birds that at a distance appear to be black. They have short, squared tails, pointed wings, and long, thin, pointed bills. The feathers of nonbreeding males and females are glossy black with white tips, giving the bird a spotted appearance. Bills are grayish-black, and the eye is dark-colored. Legs are a dull red. During the breeding season, the feathers become iridescent purple and green, and most of the spots vanish. The male sports long feathers on the breast. The bill of both sexes becomes yellow when they are in breeding condition, but males have a blue spot at the base of the beak whereas females have a reddish pink spot. Juvenile birds have uniformly gray-brown plumage and brownish-black bills. Full grown Starlings are 8–9 in. (20–23 cm) long, have a wingspan of 12–16 in. (31– 40 cm), and weigh 2–3 oz. (60–90 g). Their calls tend to be harsh squeaks, whistles, and gurgles, but they are good mimics of the calls of other birds and can imitate other sounds in the environment as well. Starlings walk; they do not hop. In flight, they resemble tiny fighter planes, with their triangular wings and short tails. Nonbreeding birds gather in huge flocks and perform spectacular mass aerial displays, especially at dusk as they ready themselves to settle at a roosting site. Related or Similar Species. European Starlings often occur in mixed flocks with other “blackbirds” with which they could be confused. The Common Grackle (Quiscalus quiscala) is larger, has a more elongated body and a proportionately much longer tail. Its iridescent feathers are not speckled, and its bill is never yellow. The eye, however, is bright yellow. The male Brown-headed Cowbird (Molothrus ater) is roughly the same size as a Starling,

238 n VERTEBRATES (BIRDS) but its head is distinctly brown, the feathers are not spotted, and the bill is conical in shape and always dark brown in color. Male Brewer’s Blackbirds (Euphagus cyanocephalus) also have glossy black plumage with a green or dark-blue sheen in the breeding season. They are similar in size to Starlings and have straight bills, but have bright yellow eyes. Introduction History. The arrival of the European Starling in North America traces to late nineteenth-century attempts by acclimatization societies to create a familiar landscape for European immigrants. The American Acclimatization Society, under the leadership of Eugene Scheiffelin, released 80–100 Starlings into New York’s Central Park in 1890– 1891. Schieffelin’s goal was to have all the birds mentioned in the works of William Shakespeare brought to the United States. (He also brought over the House Sparrow from England. See Birds, House Top: the European Starling is native to Europe and western Asia. (Adapted Sparrow.) In Henry IV, Hotspur from map at http://en.wikipedia.org/wiki/File:Sturnus_vulgaris_map.png.) says, “I’ll have a Starling . . . to Bottom: The European Starling is found in all 50 states and Puerto Rico. speak nothing but ‘Mortimer.’ ” (Adapted from “European Starling” [map]. Cornell Lab of Ornithology. Several attempts to introhttp://allaboutbirds.org/guide/european_starling/id.) duce Starlings were made from 1850 to 1900, but the first success came with the release of 60 birds in Central Park in 1890. Fifteen pairs survived. The following year, another 40 were set free. During the first 10 years, the population was contained in the greater New York City area. Thereafter, European Starlings rapidly increased their numbers and expanded their range north, south, and west. They reached Alaska by 1970. Within 75 years of introduction, Starlings had dispersed across the entire continent. Habitat. Starlings are commonly seen in urban areas and other disturbed sites. They feed on the ground in open areas with short grass, including suburban lawns and city parks. They also infest feed lots and agricultural areas, where they feed on grains and other crops. They may fly great distances from roosting sites in tree tops, under bridges, or in other open structures to their feeding grounds. They are secondary cavity-nesters: they do not excavate their own nest sites, but occupy those made by other birds, or mammals or humans. They

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A. European Starlings are about the size of a robin but walk, rather than hop. (Steve Byland/Shutterstock.) B. Nonbreeding birds assemble in huge flocks and perform what appear to be well-coordinated mass aerial displays. (Vasily A. Ilyinsky/Shutterstock.)

are not fussy about location and will build nests in holes in trees, crevices in buildings, rain gutters, under the eaves of roofs, in roof vents and attics, and in birdhouses. Diet. European Starlings are omnivores. They consume a variety of invertebrates, including earthworms, beetles, grasshoppers, spiders, and snails, and also feed on seeds, berries, and fruits such as apples, pears, and cherries. By inserting their bills into the ground or into food items and then opening their beaks, they can pry fruits open to extract any seeds or insects inside. Favorite foods reportedly include the berries of poison ivy and Virginia creeper, blackberries, mulberries, and elderberries. Life History. Breeding pairs form and begin to select nesting sites in late winter or early spring. The nests are constructed of dried grasses and other materials and typically fill the nest cavity. The female lays a clutch of 4–6 blue eggs. She may produce two or three clutches during the breeding season, which extends into July. The eggs incubate for 15 days, and hatchlings remain in the nest another 21–23 days. Both parents incubate eggs and feed the young birds. Fledglings follow their parents and beg for food for several days after leaving the nest. When they become independent, the juveniles congregate in flocks with other young Starlings. At the end of the breeding season, the parents again become gregarious and spend the nonbreeding season feeding and roosting as members of large flocks. Impacts. Much of the trouble associated with Starlings comes from their being nuisances due to the fact that they congregate in such large, noisy flocks. In cities, their acidic guano can coat buildings and sidewalks and corrode statues and the paint on cars. Diseases such as salmonella and histoplasmosis can proliferate at established roosts. Droppings have the potential to contaminate animal feed and water sources. Large flocks are able to inflict serious damage to crops such as grain, grapes, olives, and cherries. Starlings massing near airport runways pose a real danger to arriving and departing airplanes because they can clog engines, damage planes, and, when an entire flock collides with a plane, can cause planes to crash. The ecological impacts of the European Starling in the United States are related to their aggressive takeovers of nest cavities sought or occupied by other bird species. Declines of woodpeckers, martins, tree swallows, and bluebirds have been blamed on the presence of Starlings. Starlings are also implicated in the spread of the seeds of exotic weeds.

240 n VERTEBRATES (BIRDS) The European Starling has also been introduced to South Africa, Australia, and New Zealand. It has been nominated by the Global Invasive Species Programme as one of the 100 “World’s Worst” invaders. Management. Direct population reductions may be accomplished through poisoning with Starlicide Complete, trapping, or shooting, but most efforts try to repel or exclude Starlings. At airports, livestock facilities, and some urban roosting sites, frightening the birds with noises, including recordings of their own distress calls, has had at least temporary success. Barricading entrances to cavities with screens or other covers will eliminate nesting sites. Habitat modification involving the removal of water sources and foraging sites has had some success at airports.

Selected References Adeney, Jennifer Marion. “European Starling (Sturnus vulgaris).” Introduced Species Summary Project, Columbia University, 2001. http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/ inv_spp_summ/Sturnus_vulgaris.html. Johnson, Steve A., and Walter Givens. “Florida’s Introduced Birds: European Starling (Sturnus vulgaris).” Document WEC255, Department of Wildlife Ecology and Conservation, University of Florida/IFAS, 2009. http://edis.ifas.ufl.edu/UW300. Withers, David Ian. “Origins of the European Starling in the United States.” Tennessee Department of Environment and Conservation, 2000. http://www.state.tn.us/environment/tn_consv/archive/ starlings.htm.

n House Finch Also known as: Linnet Scientific name: Carpodacus mexicanus Family: Fringillidae Native Range. Western North America. Prior to the late nineteenth century, House Finches were found in the southwestern states. They expanded their range northward and were first reported in the Columbian Basin of Oregon in 1885. Dam construction and irrigation projects apparently facilitated their spread into eastern Washington State in the early twentieth century; they were found in the western part of the state by the 1950s. Today, naturally occurring populations inhabit the drier habitats west of the Rocky Mountains from southern British Columbia to southern Mexico. Originally occupying undisturbed desert scrub, desert grasslands, chaparral, oak savannas, and low elevation open coniferous forests, they adapted to human-dominated environments and moved into suburban and agricultural areas. They also crossed the Rockies onto the High Plains. Distribution in the United States. House Finches are now common birds throughout the eastern United States and have also been introduced into Hawai’i. Description. House Finches are small, sparrow-like songbirds. Adults are 5–6 in. (13– 14 cm) long and have wingspans of 8–10 in. (20–25 cm). The male usually has a rosy-red forehead, stripe over the eye, breast, and rump. The brown back has dark brown streaks, and light-brown streaks appear on the flanks and belly. Some males are orange or even yellow; plumage color depends on diet. Females are brown with a plain brown head, finely streaked underparts, and two pale wingbars. They have no eye stripe. Both sexes have squarish, slightly notched brown tails and blunt, rounded beaks. Juveniles look like females; males acquire their color in their second spring.

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House Finches have a melodic warbling song with a few harsh notes and a downward trend. Related or Similar Species. The most similar bird in the eastern United States is a congener, the Purple Finch (Carpodacus purpureus). Purple Finches are somewhat more robust. Males have more red on their heads and breast than House Finches and lack brown streaks on their flanks and bellies. Females have broad white stripes over and under the eye, a larger beak, and bolder striping on breast and belly than female House Finches. Female House Sparrows (see Birds, House Sparrow) could also be mistaken for female House Finches. The former have light brown stripes on the back and unstreaked undersides. Pine Siskins (Carduelis pinus) are considerably smaller and more heavily streaked than female House Finches; they have yellow patches on the wings (not always obvious) and slender, pointed bills. Introduction History. House Top: The House Finch is native to the western United States, where its Finches were introduced into range has been expanding since the 1960s. Bottom: The House Finch is Hawai’i in the 1880s. Finches a native transplant and now a common songbird in the eastern half of in the eastern United States the United States. It has also been introduced into Hawai’i. (Both maps trace their origins to the 1930s, adapted from All About Birds, 2009.) when House Finches were sold in pet stores in New York City as “Hollywood Finches.” The selling of wild birds became illegal in 1940, and some dealers apparently released their captive finches on Long Island to avoid legal action. For the first few years, the population’s survival was tenuous, but by the 1950s, House Finches were established in New York City. The population then irrupted, and finches spread rapidly up and down the East Coast, probably helped by the increasing presence of bird feeders in suburban and urban areas of the United States. By the 1980s House Finches had reached the Mississippi River, and today the eastern and western distribution areas seem to have merged; House Finches are now found across the continent. The population explosion ceased in the early 1990s with appearance of mycoplasmal conjunctivitis. This infection causes the eyelids to become red, swollen, and encrusted and can lead to blindness and starvation. The disease first appeared in the Washington, D.C.,

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A. The male House Finch has a rosy-colored forehead and light brown streaks on the flanks and belly. (Stubblefield Photography/Shutterstock.) B. The female House Finch has a plain brown head and finely streaked underparts. There are two pale wing bars. (Chris Hill/Shutterstock.)

area during the winter of 1993–1994. Two years later, it had spread across the Appalachians, and by the following winter, it was in the Midwest and beginning to show up on the Great Plains. The disease is most prevalent in winter when the birds flock at feeders. By 1999, scientists were reporting that House Finch numbers were roughly 40 percent less than expected before the epidemic began. The rapid decline in House Finch populations coincided with an increase in the number of House Sparrows in some affected areas. The virulence of the disease may be abating. Current estimates are that only 5–10 percent of the population is infected, whereas at the peak of the disease, 50 percent of the eastern finch population may have been died from it. (In 2004, the disease appeared in the Pacific Northwest and has reached epidemic proportions there.) Habitat. Where they have been introduced, House Finches inhabit backyards, urban parks, farmland, and forest edge. They congregate at bird feeders and like to perch in high trees close by. Nesting sites include ledges on buildings, shrubs, debris piles, hollows in trees, and birdhouses. Diet. House Finches consume almost any type of seed and also eat ripening fruits, flowers, and buds. In addition to bird seed at feeders, where sunflower seeds are preferred, the finches also extract seeds from thistle, dandelion, and mistletoe and forage on the ground. The males acquire their rosy color after the postnuptial molt by eating carotenoid-rich red berries and fruits. Cherries and mulberries are among those preferred. Life History. Pair formation begins in late winter. Females tend to choose the males with the brightest coloration. The breeding season starts in early spring when the female constructs a small cuplike nest of fine grasses, hair, or other fiber. She lays 3–6 small, pale blue eggs that are flecked with black on the larger end. The female incubates the eggs for 12–14 days, while the male feeds and guards her. The nestlings fledge when 11–19 days old. The male will feed the fledglings for several days until the female has built a new nest. Most House Finches produce at least two clutches during the breeding season. The young of the year disperse widely and congregate at food sources. Nonbreeding adults and juveniles are especially gregarious in fall and winter and may form large, mobile foraging flocks. Some in the northeastern United States migrate in winter. House Finches are mature at one year of age and may live more than 10 years. Impacts. Most people welcome and encourage these colorful little songsters at their backyard feeders. However, as the House Finch spread through the eastern United States,

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dramatic declines in Purple Finches and House Sparrows took place in newly invaded areas. The range of the Purple Finch has shifted northward, confining it more and more to the conifer forests avoided by the House Finch. Part of this range shift may be due to climatic change and not solely the influence of increasing House Finch populations. House Sparrow numbers declined wherever House Finches invaded, suggesting the latter were outcompeting the former. (Later, when finch numbers decreased, the sparrows rebounded, reinforcing this interpretation.) Recent research has also found evidence of an evolutionary response among House Sparrow populations, a phenomenon known as character displacement. At bird feeders, the sparrows prefer smaller seeds such as millets, whereas the finches prefer sunflower seeds. Where the two species both occur, sample measurements indicate that House Sparrow beak depths are smaller than before the finch invasion and they are becoming better adapted to specialize on the small seeds neglected by finches. Since 1993, a bacterial eye infection (mycoplasmal conjunctivitis) has swept through eastern House Finch populations. There is a possibility that this disease could be spread at feeders to other wild birds, such as Blue Jays (Cyanocitta cristata) and American Goldfinches (Carduelis tristis), as well as to domestic poultry. Management. Since most people like having these birds around, management is largely directed at reducing the infection rate of conjunctivitis among House Finches. This can be accomplished by homeowners cleaning bird feeders and disposing of old seed and accumulated bird droppings. For those who find House Finches to be a nuisance, fruits can be protected from finch depredation with plastic netting, and potential nesting sites can be eliminated.

Selected References Cooper, Caren, Wesley Hochachka, and Andre´ Dhondt. “Why Did House Sparrow Numbers Rise, Then Fall?” Birdscope 21(2): 2007. http://www.birds.cornell.edu/Publications/Birdscope/ Spring2007/sparrow_numbers.html. Dewey, T., K. Kirschbaum, and J. Pappas. “Carpodacus mexicanus,” Animal Diversity Web, University of Michigan Museum of Zoology, 2002. http://animaldiversity.ummz.umich.edu/site/accounts/ information/Carpodacus_mexicanus.html. “House Finch.” All About Birds, Cornell Lab of Ornithology, 2009. http://www.allaboutbirds.org/ guide/house_finch/id. Johnson, Steve A., and Jill Sox. 2009. “Florida’s Introduced Birds: House Finch (Carpodacus mexicanus).” Document WEC 253, Department of Wildlife Ecology and Conservation, University of Florida/IFAS. http://edis.ifas.ufl.edu/uw298. Kammermeier, L. “Population Dynamics of the House Finch.” Birdscope, 13(2): 15, 1999. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Carpodacus mexicanus (bird).” ISSG Global Invasive Species Database, 2005. http:// www.invasivespecies.net/database/species/ecology.asp?si=485&fr=1&sts. Wootton, J. Timothy. “Ecology and Evolution of Invading and Restored Species.” Department of Ecology and Evolution, University of Chicago, n.d. http://woottonlab.uchicago.edu/index/ invasive-species/ecology-and-evolution-of-invasive-and-restored-species.

n House Sparrow Also known as: English Sparrow Scientific name: Passer domesticus Family: Passeridae Native Range. Eurasia and North Africa. Occurs from the United Kingdom eastward through Siberia and southeastward to the Arabian Peninsula and Indian subcontinent, but

244 n VERTEBRATES (BIRDS) is not native to Italy. In North Africa, it is found in coastal areas and at isolated oases in the Sahara. They have been associated with human settlements for centuries. Distribution in the United States. Established in all 48 of the contiguous states and in Hawai’i and Puerto Rico. Description. This Old World sparrow is a small brown bird common in towns and cities. It has a relatively large head and short wings. The legs are pink. The male has a black bib and mask, gray cap and rump, and chestnut-colored nape. The side of the head and underparts are pale gray, and the brown back is streaked with black. The conical bill is black in summer and yellowish in winter. Nonbreeding and immature males have less black on the throat and breast. The female is brown all over, with tawny streaks on her back and a strong buffcolored eye line edged below by a dark brown stripe. Her throat and breast are light and Top: The native range of the House Sparrow includes all of Europe, much unstreaked. The bill is yellow. of Asia, and parts of North Africa. (Adapted from map at http:// Young birds resemble females. House Sparrows are 5.25– en.wikipedia.org/wiki/File:PasserDomesticusDistribution.png.) Bottom: The House Sparrow is a common bird of the built environment in all 48 6.25 in. (133–159 mm) long. contiguous states, Hawai’i, and Puerto Rico. In the relatively short time they have been naturalized in the United States, they have evolved in accord with regional climatic differences across North America. Northern birds are larger than southern ones; desert populations have much lighter coloration than populations in the humid east or Pacific Northwest. The song of the House Sparrow is a series of chirps. Related or Similar Species. Only one other Old World sparrow has become established in the United States: the European Tree Sparrow (Passer montanus), restricted to St. Louis, Missouri, and nearby Illinois. It can be distinguished by its rufous crown, white collar, and prominent black patch in the white cheek. Introduction History. Some early introductions of the House Sparrow (then called the English Sparrow) were attempts to control insect pests, especially the elm spanworm (Ennomos subsignaria), a defoliator of shade trees. Many introductions were the results of

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A. The male House Sparrow has a black bib and mask. (Francis Boose/Shutterstock.) B. The female House Sparrow is brown with tawny streaks on the back and a strong buff-colored eye line. (Stubblefield Photography/Shutterstock.)

activities of acclimatization societies; and at first, citizens tenderly cared for the birds. The first introduction into the United States consisted of eight pairs from England released in Brooklyn, New York, in 1851. More birds were imported the following year, and 50 of them were released. Neither group thrived. In 1853, birds held and nurtured in a tower in the Greenwood Cemetery were released and protected. These sparrows did survive; they multiplied, and people carried them to other towns and cities in the region. Other deliberate introductions, commonly by acclimatization societies, include those in Portland, Maine (1854), Peace Dale, Rhode Island (1858), Boston, Massachusetts (1858), and New Haven, Connecticut (1867). House Sparrows were brought to San Francisco, California, in 1875. The birds prospered in part by eating seeds in the dung of urban horses. They rapidly dispersed along carriage roads into agricultural areas, where they became pests. House Sparrows are now found in almost all populated parts of the country. Numbers are believed to have peaked in the early twentieth century before motorized vehicles replaced horses. Another period of decline followed the conversion to modern industrial agriculture in the 1960s. Habitat. These birds are creatures of human-modified environments. They are found in cities, suburbs, and agricultural settings, but not in undisturbed forests, grasslands, or deserts. By preference cavity nesters, they build their nests in crevices in and on buildings, in the hollow posts of traffic signs, in the rafters of porches, in birdhouses, in holes in trees, or in any other sheltering location. Diet. House Sparrows primarily forage on the ground for seeds, but also feed on fruits, insects, and garbage. It is not unusual for them to extract dead insects from the grills of automobiles and to hop about the parking lots of fast food restaurants looking for discarded food. Life History. House Sparrows begin to nest as early as February, when monogamous pairs form. The nests, usually in small colonies, consist of dried plant material, feathers, string, and shreds of paper. The female usually lays 3–6 speckled pale blue eggs per clutch and may produce up to four clutches a year. Incubation starts after the last egg in a clutch has been laid and continues for 10–12 days. The young fledge about 14 days after hatching. They may live more than 12 years. Impacts. Today, the House Sparrow is considered mainly a nuisance species in cities and towns when large groups create noise and messy, corrosive droppings. In the early years of

246 n VERTEBRATES (BIRDS) their invasion of the United States, they were an agricultural pest, eating ripening grains, destroying fruits, and consuming or fouling seeds and other feed. To some extent, the negative impacts were balanced by the birds’ consumption of insect pests, including cabbage worms and cotton caterpillars. House Sparrows will evict native birds from their nest cavities and were implicated in declines of the Eastern Bluebird (Sialis sialis), Purple Martin (Progne subis), and some woodpeckers during the twentieth century. Sparrow populations have declined since the advent of large monoculture farms in the 1960s. Declining numbers of sparrows in the central and eastern United States and recovery programs targeting bluebirds and martins have mitigated their effects on native birds. Management. Habitat modifications that eliminate roosting and nesting sites can reduce local House Sparrow populations. So, too, can reduction of food sources by cleaning up garbage dumps and protecting berries and other small crops with bird netting. The birds can be repelled with noise and scarecrows. Since these nonnatives are not protected by the Migratory Bird Act, they may be trapped or shot.

Selected References “House Sparrow.” All about Birds, Cornell Lab of Ornithology, 2009. http://www.allaboutbirds.org/ guide/House_sparrow/id. Laycock, George. The Alien Animals. The Story of Imported Wildlife. New York: Ballantine Books, 1966. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Passer domesticus (bird).” ISSG Global Invasive Species Database, 2006. http:// www.issg.org/database/species/ecology.asp?fr=1&si=420. Roof, J. “Passer domesticus.” Animal Diversity Web, University of Michigan Museum of Zoology, 2001. http://animaldiversity.ummz.umich.edu/site/accounts/information/Passer_domesticus.html.

n Japanese White-Eye Also known as: Me-jiro, Dark-green White-eye Scientific name: Zosterops japonicus Family: Zosteropidae Native Range. Eastern Asia. Native to Japan, eastern and southern China, Vietnam to Burma in Southeast Asia, Taiwan, Hainan Island, Ryukyu Islands, and the northern Philippines. Distribution in the United States. Established on all the major islands in Hawai’i, where it is now the state’s most abundant bird. Description. This extremely active and acrobatic little bird has an olive-green head, neck, and back. The white eye-ring appears almost to be embroidery. The throat and underside of the tail are yellow, the breast gray, and the belly dull white. Flanks are brownish. The wings and tail are dark brown; upper tail feathers and wing feathers are outlined in green. Legs and feet are black. They measure 4–4.5 in. (10–12 cm) long. Juveniles lack the white eye-ring. White-eyes forage in trees in small flocks and often hang upside to down to reach food. Introduction History. The Japanese White-eye was first introduced to O’ahu in 1929 by the (Hawaiian) Territorial Board of Agriculture and Forestry to control insects. It was taken to the island of Hawai’i in 1937 and now can be found on all the major islands.

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Habitat. In Hawai’i, the Japanese White-eye lives in trees and shrubs in rainforest, open deciduous forests, agricultural areas, towns, and city parks. It occurs from sea level to treeline in both arid and humid parts of the islands. Diet. Japanese White-eyes probe foliage at all levels for insects, including beetles, fly larvae, and spiders. They also eat seeds, nectar, and fruit. They switch from one food source to another depending on availability. Life History. The breeding season extends from February to December, but there is a distinct peak in activity in July and August. Neat cuplike nests are built at various levels in trees. They are constructed of grass, string, cobwebs, leaves, and mosses and attached to the fork of a branch with spider webs. If human habitation is nearby, the nest is often lined with human hair. The female lays 3–4 white eggs that hatch after an 11-day incubation period. Newborn chicks are altricial; their eyes Top: The Japanese White-eye is native to East Asia. (Adapted from open about five days after hatch- MacKinnon, J., and K. Phillips, A Field Guide to the Birds of China. ing. The young fledge 10–12 days Oxford: Oxford University Press, 2000.) Bottom: The Japanese Whiteafter hatching. Often the young eye is invasive only in Hawai’i, where it has become the state’s most abuncannot fly when they first leave dant bird. the nest, but they acquire this ability in 1–6 days. Fledglings remain with their parents for 15–20 days, at which point the adults begin to build a new nest and force the juveniles out of the breeding territory. The white eye-ring is apparent at 23 days of age; and by 30 days, the young look like adults. Young birds gather in flocks until the next year, when they will begin to form pairs and breed. Impacts. The Japanese White-eye, unlike many exotic birds in Hawai’i, has invaded native montane forest and is currently the most abundant land bird on the main islands. It appears to compete directly with some endemic Hawaiian Honeycreepers for food. As a generalist, the White-eye can switch its feeding specialty to those items most prevalent in a variety of forest types or to less desirable insects, fruits, and flowers when preferred food sources become depleted. In wet forests, it competes with the Elepaio (Chasiempis sandwichensis) for foliage insects on low branches and the Apanane (Himatione sanguinea) for nectar. In high-

248 n VERTEBRATES (BIRDS) altitude forests, it competes with the Iiwi (Vestiaria coccinea) for nectar. Evidence suggests that the presence of White-eyes leads to undernourishment of the young of some native birds such as the endangered Akepa (Loxops coccineus), resulting in stunted adults more vulnerable to diseases such as avian malaria, higher infestations of chewing lice, higher mortality rates, and declining populations. It may have lesser impact on the Common Amakihi (Hemignathus virens), which has a similarly broad niche. The Japanese White-eye is an active and acrobatic little bird that sports a The Japanese White-eye has distinct white eye-ring. (K. W. Bridges, “Common Campus Birds,” the potential to spread invasive University of Hawai’i at Manoa. http://www.botany.hawaii.edu/biolplants into undisturbed native ogy101/birds/japanese_white_eye.htm.) Hawaiian forests. It is known to disperse, for example, the velvet tree (Miconia calvescens; see Volume 2, Trees, Velvet Tree), lantana shrubs (Lantana camara; see Volume 2, Shrubs, Lantana), and the fire tree (Myrica faya; see Volume 2, Trees, Fire Tree). On a positive note, the Japanese White-eye may be replacing extinct species of honeycreeper that dispersed native shrubs. Management. There appears to be no effort to control the spread of these birds, and indeed, it is unlikely any measure would be effective.

Selected References Foster, Jeffrey T., and Scott K. Robinson. “Introduced Birds and the Fate of Hawaiian Rainforests.” Conservation Biology 21(5): 1248–57, 2007. “Introduced Japanese White-Eyes Pose Major Threat to Hawaii’s Native and Endangered Birds.” ScienceDaily, 2009. http://www.sciencedaily.com/releases/2009/09/090917131540.htm. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Zosterops japonicus (Bird).” ISSG Global Invasive Species Database, 2006. http:// www.issg.org/database/species/ecology.asp?si=954&fr=1&sts. “Zosterops japonicus.” Senior Seminar: Introduced Species in Hawaii. Department of Biology, Earlham College, 2002.

n Monk Parakeet Also known as: Quaker parrot, Quaker conure Scientific name: Myiopsitta monachus Family: Psittidae Native Range. South America. Four subspecies are recognized, three in the lowlands east of the Andes: M. m. monachus from southeastern Brazil (Rio Grande do Sul) into Uruguay and northeastern Argentina; M. m. cotorra from eastern Bolivia south through Paraguay;

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and M. m. calita in the Patagonian region of Argentina. The disjunct upland population in Bolivia, currently recognized as the subspecies M.m. luchsi, is probably a separate species as evidenced by its different habitat, appearance, and nesting behavior. Genetic evidence traces the origins of the Monk Parakeets in the United States to the region from Entre Rios, Argentina, to Rio Grande do Sul, Brazil, near the Uruguayan border. Other records confirm that most animals trapped for the pet trade were exported from eastern Argentina and Uruguay. Distribution in the United States. Populations come and go, but the bird appears to be established in Alabama, Connecticut, Delaware, Illinois, Florida, Louisiana, New Jersey, New York, Oregon, Rhode Island, Texas, and Virginia; and perhaps also in Colorado, Missouri, Ohio, and South Carolina. The largest populations are in Florida and Connecticut, and in both states, they are increasing in numbers and Top: The Monk Parakeet is native to temperate lowlands east of the Andes expanding their ranges. Monk Mountains in South America. (Adapted from Russello et al. 2008.) Parakeets were eradicated from Bottom: Monk Parakeets are established in several urbanized locations California in the 1970s. Monk across the United States. (Adapted from Johnson and Logue 2009.) Parakeets have been observed in Hawai’i, but have not become established. They are well established in Puerto Rico. Description. The Monk Parakeet is a small, stocky, mostly green parrot about 11.5 in. (30 cm) from head to tail. The wingspan is about 19 in. (53 cm), and the weight is 2–3 oz. (90–120 g). The forehead, throat, and breast are gray with white barring. The lower abdomen and vent areas are yellow, and the flight feathers are dark blue. The eyes are brown, the bill pale yellow or orange, and the legs are gray. Immatures have green foreheads. Monks are highly social and noisy; they chatter continually at the nest. They possess a variety of calls and squawks and are especially loud when flying. Monk Parakeets weave large communal nests of sticks, usually 30 ft. (10 m) or more above the ground. They utilize trees, power poles and towers, and the nests of other birds as supports for these constructions, which may become 3 ft. (1 m) in diameter and weigh up to 440 lbs. (200 kg). Each pair has its own nest cavity within the structure, the entrance

250 n VERTEBRATES (BIRDS) pointing downward. The nest is used for breeding and for shelter year round, and is probably a major reason that the Monk Parakeet has been able to survive in northern states. It is the only parrot that builds a stick nest; others species are cavitynesters. Related or Similar Species. Three other parakeets introduced to the United States are about the same size and might be confused for Monk Parakeets. The White-winged Parakeet (Brotogeris versicolurus) and the Yellow-chevroned The Monk Parakeet is a stocky, mostly green parrot about a foot long. Parakeet (B. chiriri) are both They are highly social. (Steve Baldwin, BrooklynParrots.com.) smaller (8.75 in. or 222.5 mm total length) than monks and have green heads and bodies with yellow patches showing on their folded wings. In flight, both display yellow bands on the underwing (i.e., the greater coverts are yellow), which are lacking in the Monk Parakeet. The Nanday Conure or Black-hooded Parakeet (Nandayus nenday) has a black head and bluish breast. Budgerigars (Melopsittacus undulatus), a fourth exotic parrot, are much smaller (7 in. or 178 mm total length) than Monk Parakeets and lack the gray foreheads and throats. Their long pointed tails and yellow wing stripe distinguish them in flight. Introduction History. From the late 1960s into the early 1970s, some 64,000 Monk Parakeets were imported into the United States. This intelligent species ranks as one of the 10 best talkers among parrots, and its cost is reasonable. Birds were exported from Argentina, perhaps because they were considered agricultural pests in that country. Their importation into the United States was not banned until the Wild Bird Conservation Act of 1992, but these popular cage birds continue to be bred by aviculturalists here. Releases, intentional or not, continue to replenish feral populations and start new ones. Feral populations had become established in at least 21 urban locations in seven states by the early 1970s. All stemmed from accidental or intentional releases by zoos, the pet industry, or pet owners. The concern over the species becoming an agricultural pest led the U.S. Fish and Wildlife Service between 1970 and 1975 to capture or shoot free-roaming parrots and try to eradicate feral populations. They eliminated monks from California and reduced the overall number of populations to seven in five states. Nonetheless, the number of and size of populations grew after 1975. By 1995, the bird could be found at 76 sites in 15 states. Monk Parakeets were first reported from Florida in 1972. They were widespread by 1992 and today may number 50,000 to 150,000 birds in 16 counties. The urbanization of eastern Florida with the planting of thousands of ornamental plants that together produced fruit and nectar year round provided an optimal habitat for the bird. Birdseed at feeders supplemented the diet, particularly in winter. Monk Parakeets in New Jersey are believed to be descendents of birds released in New York in the 1960s. In 1968, parakeets escaped from a damaged crate at John F. Kennedy

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Carolina Parakeet

T

he eastern United States was once home to North America’s only native parakeet, the Carolina Parakeet (Conuropsis carolinensis), and some have suggested that the Monk Parakeet might come to fill its empty niche—and, like it, become an agricultural pest. Well into the nineteenth century, the colorful bird was an abundant resident of sycamore and bald cypress bottomland forests from the Gulf coast northward almost to the Great Lakes. Like most parrots, it was highly social, noisy, and fed on a variety of plant foods, including cockleburs, sandspurs, pine seeds, and bald cypress seeds. It also foraged on grain and orchard crops. The Carolina Parakeet was up to 13 in. (33 cm) long from the head to the tip of the tail. Its body was bright green, and its head yellow. The forehead and lores were bright orange. Unlike Monks, Carolina Parakeets nested in tree cavities. It became popular in the early pet trade because of its colorful plumage, but was a poor talker. Its bright feathers were also in demand for a time for women’s hats. The birds had the unfortunate habit of flocking to trapped or injured parakeets in response to their distress calls, and this made it relatively easy for farmers or hunters to shoot to trap large numbers at a time. John James Audubon noted a rapid decline in the number of parakeets in 1831. The last confirmed sightings in the wild were made in 1904 at Lake Okeechobee in Florida by the respected ornithologist Frank Chapman. The last known captive bird died in 1918 at the Cincinnati Zoo, and the Carolina Parakeet was officially declared extinct in 1939. The demise of the Carolina Parakeet was likely due to a combination of factors. Slaughter by farmers trying to protect crops usually is identified as the cause of extinction, but the birds were also trapped for food, feathers, and pets. Destruction of their bottomland habitat was undoubtedly a contributing factor. Other possibilities include introduced diseases—especially those originating in poultry—and competition for nesting and roosting cavities by feral honey bees, a species introduced to North America during the colonial period.

Airport. The first parakeet was recorded from Oregon in 1977. In 1980–1981 a nest was built near the Portland International Airport, and a small population has persisted since that time. Habitat. In their native lands, Monk Parakeets prefer open country with tall, isolated trees for nesting. They are found in savannas and woodlands, and in farmland, open eucalyptus forest, and palm groves. The widespread planting of eucalyptus trees as windbreaks in the pampas allowed them to expand their range onto the grasslands. In the United States, all populations are urban. Diet. Monk Parakeets are largely granivorous and consume primarily the seeds of wild grasses, sedges, and sunflowers. They also feed on berries, fruits, and occasionally insects. In agricultural settings, they forage on domesticated grasses such as maize, wheat, rice, and sorghum and are considered major agricultural pests in South America. In the cities of North America, they feed on the buds, seeds, and fruits of ornamental plants and, in winter, almost exclusively on birdseed put out for them on feeders. Life History. Breeding begins in North America in spring as the photoperiod increases. Clutches contain 4–7 eggs. Eggs hatch asynchronously, beginning about 20 days after the

252 n VERTEBRATES (BIRDS) first one was laid. The nestlings are initially covered with yellow down and remain in the nest for about 40 days, fed by the parents. Fledglings rarely move far from their birthplace, and often add their own chambers to the communal nest. Immature birds become sexually mature at age 2, but may not breed. Instead, they stay with their parents and help maintain the nest and care for the next generation of their siblings. Impacts. In the United States, the Monk Parakeet is not the agricultural pest it was predicted to become in the 1970s. All populations are, to date, urban. There is little or no evidence suggesting they affect native wildlife. Instead they seem to have brightened the lives of many urban dwellers who delight at seeing these colorful birds at their winter bird feeders. The large nests do pose a problem on transmission line towers and distribution poles, which can be damaged. When they are wet, the nests can cause short circuits and disruption of electric power service. It is costly and can be dangerous to remove nests and repair poles and towers. Monk Parakeets can also be a nuisance because of the noise they make. Management. Control of monk parakeets is difficult. The U.S. Fish and Wildlife Service’s efforts, which came early in the history of introductions of the birds to the United States, only resulted in eliminating the monks in California. Destruction of nests just causes the birds to build new ones, often nearby. Controlling population sizes may be achieved by limiting accessible food resources, for example, by removing bird feeders or not growing fruitbearing ornamental plants. Trapping and selling the parakeets might be an option, since there remains a strong market for the birds. The issue of management is complicated by the fondness many people have for these birds and the political strength of animal rights organizations. Since any eradication program would be labor intensive, costly, and controversial, and since the birds are not currently an ecological problem, many in wildlife management think the effort to reduce populations simply is not worth the trouble.

Selected References Campbell, T. S. “The Monk Parakeet, Myiopsitta monachus.” Institute for Biological Invasions, University of Tennessee, Knoxville. Invader of the Month, 2000. Gluzberg, Yekaterina. “Monk Parakeet (Myiopsitta monachus).” Introduced Species Summary Project, Columbia University, 2001. http://www.columbiauniversity.org/itc/cerc/danoff-burg/invasion _bio/inv_spp_summ/Myiopsitta_monachus2.html. Johnson, Steve A., and Sam Logue. “Florida’s Introduced Birds: Monk Parakeet (Myiopsitta monachus).” Document #WEC257, Department of Wildlife Ecology and Conservation, University of Florida/ IFAS, 2009. http://edis.ifas.ufl.edu/UW302. Russello, Michael A., Michael L. Avery, and Timothy F. Wright. “Genetic Evidence Links Invasive Monk Parakeet Populations in the United States to the International Pet Trade.” BMC Evolutionary Biology 8: 217, 2008. Stafford, Terri. “Pest Risk Assessment for the Monk Parakeet in Oregon.” Oregon Department of Agriculture, 2003. http://www.oregon.gov/OISC/docs/pdf/monkpara.pdf.

n Mute Swan Scientific name: Cygnus olor Family: Anatidae Native Range. Eurasia. The Mute Swan breeds in temperate areas from Northwest Europe to Russia, Ukraine, and Kazakhstan. It occurs south of the taiga in southern Siberia and northern China. Wintering grounds are primarily in subtropical regions that lie south of

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nesting areas. These areas include the eastern Mediterranean, the Black and Caspian seas region, the Persian Gulf region, Central Asia, and the Yellow Sea coast. Wild populations in Western Europe were virtually eliminated by overhunting from the thirteenth through the nineteenth centuries. Large landowners preserved groups of semidomesticated birds on their estates; so most populations today descend from feral swans. Conservation efforts in the late nineteenth century allowed Mute Swans to regain much of the former territory of their wild ancestors. Birds in the United Kingdom and Western Europe are semimigratory, in winter moving only short distances, often to the coast, where they congregate in flocks. During severe winters, when lakes and rivers freeze over, they will fly much longer distances to open water. Distribution in the United States. Mute Swans occur in the eastern United States from southern Maine to South Top: The Mute Swan was once widely distributed in the temperate Carolina and from the Atlantic regions of Eurasia, but populations were largely extirpated by coast inland to the Mississippi overhunting from the thirteenth through the nineteenth centuries. Many River drainage. Small numbers populations existing today derive from semidomesticated stock. are found in western states. (Adapted from Delany 2006.) Bottom: Mute Swans have established Mute swans are considered populations in southern New England, Long Island Sound, Chesapeake Bay, and Great Lakes areas. Small numbers occur in some western established in southern New states. (Adapted from “Winter Christmas Bird Count” [map]. http:// England, Long Island Sound, www.discoverlife.org/mp/20q?search=Cygnus+olor.) the Chesapeake Bay, and the Great Lakes region. The largest populations are in Rhode Island, Connecticut, New York, New Jersey, and Maryland. They are not truly migratory in any part of their adopted range. Description. Mute Swans are very large white waterfowl with long, gracefully curved necks. When swimming, the bill points downward. The Mute Swan has an orange bill with a diagnostic black knob at the base and a black nail at the tip. The lores are also black. Adults may have a total length greater than 5 ft. (1.3–1.6 m) and weigh 20–25 lbs. (8–11 kg). The wingspan can be 7 ft. (1.8–2.5 m). Males (“cobs”) are larger than females (“pens”).

254 n VERTEBRATES (BIRDS) Immature swans (cygnets) have two morphs, greyish brown or white. The gray cygnets have slate-gray bills, legs, and feet. The white morph has a tan bill and pinkish tan feet. Both lack the basal knob on the bill that characterizes adults. Related or Similar Species. Native swans have long necks that are held straight when swimming, and black bills. The Mute swans have long, gracefully curved necks. When swimming, they Trumpeter Swan (Cygnus buccinator) is equal in size to the point their bills downward. (Ozerov Alexander/Shutterstock.) Mute Swan. Its range is generally north of that of the Mute Swan. The Tundra or Whistling Swan (Cygnus columbianus) is considerably smaller and has yellow lores. Its distribution overlaps with that of the Mute Swan on its wintering grounds and during migration. The white Snow Goose (Chen caerulescens) might also be mistaken for a swan on the wintering grounds, but it is a much stockier bird with a shorter neck and is about half the size of a swan. Its black wing tips are diagnostic in flight. Introduction History. By most accounts, Mute Swans were introduced into the United States from Europe in the late 1800s as ornamental birds on private estates, in urban parks, and in zoos. Aviculturalists bred the birds, esteemed for their beauty and grace. Originally, swans had their flight feathers cut to keep them from flying off. However, some owners neglected to pinion their birds, and escapes established feral populations. The earliest known free-ranging populations lived along the Hudson River (1910) and on Long Island, New York (1912). These populations expanded their numbers and distribution within the states of the Atlantic Flyway. New Jersey had feral Mute Swans by 1919, Rhode Island by 1923, and Maryland by 1954. Mute Swans began to colonize the lower Great Lakes in the mid-1960s and were first sighted in South Carolina in 1993. Many populations in the eastern United States grew especially rapidly in the 1990s, but have shown signs of decline since that time. Mute Swans in the California and the Pacific Northwest are the products of local releases and escapes. There is no credible evidence to the support the hypothesis that Mute Swans were native to North America and suffered continent-wide extinction during the Pleistocene Epoch. Nor is there scientific support for the belief that Mute Swans regularly migrated from Siberia to North America. Furthermore, none of the great early American naturalists and wildlife artists, such as Mark Catesby, John James Audubon, Spencer Baird, or Elliot Coues, encountered these large birds. Habitat. Lakes, ponds, rivers, bays, estuaries, fresh and saltwater marshes. They prefer waters up to 4 ft. (1.2 m) deep where they can reach submerged vegetation, but will move to deeper water when the shallow water freezes in winter. Diet. Mute Swans consume submerged aquatic vegetation (SAV). Studies in the Chesapeake Bay revealed a preference for widgeon grass (Ruppia maritima). They also consume eel grass (Zostera marina), wild celery (Vallisneria americana), and several pondweeds (Potamogeton spp., and others). They will pull up whole plants to eat or to feed to cygnets.

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Life History. Defense of large (6–13 ac. or 2.4–5.3 ha) nesting territories begins in February, and nesting starts in March or early April. The mating ritual involves what is known as “busking,” when males raise their wings and fluff their feathers while twirling in place. Pair formation is not for life as legend has it, but swans are monogamous for the season and pairs may be stable for years at a time. The female performs most of the nest building, using rushes, cattails, reeds, and stems of other marsh plants to construct a large nest 4–6 ft. (1–2 m) in diameter, often on a mound safely above water level. Both males and females are highly aggressive toward intruders in their territories. Clutch size varies from 4 to 10 eggs. The young cygnets hatch about 35 days after the last egg is laid. In the Mid-Atlantic region, hatching usually takes place in early June. Mute swans generally nest only once a year, but if the eggs are destroyed early in the season, they will nest a second time. Cygnets are precocial and begin swimming within a day or two of hatching. Families typically remain on the breeding territory away from other family groups or nonbreeding adults during the first two months or so. Cygnets grow rapidly and can fly at 4–5 months of age; they are fully grown at 6 months. Juveniles are forced out of the nesting territory before the next breeding season. Juveniles and subadults often gather in large flocks near open salt water and molt, becoming flightless for a short time. Mute Swans become sexually mature at age 2, but most will not nest until they are 3–5 years old. Swans can live in the wild up to 19 years, but the average lifespan is about 7 years. Impacts. In the Chesapeake Bay, the Mute Swan’s consumption of SAV is of major concern. SAV provides essential cover and nursery areas for a variety of fish and shellfish and feeding grounds for a large number of native waterfowl, and it has already been seriously depleted in estuaries of the bay due to development and pollution. Whereas native ducks, geese, and swans use the area as wintering grounds and consume SAV for only a season, Mute Swans are year-round residents and consumers. Plants such as wild celery reproduce and recover from wintering grazing pressures when the native waterfowl are absent. Mute Swans could impede the seasonal and long-term recovery of SAV and reduce winter forage for native birds. Loss of SAV is implicated in population declines of Canvasbacks (Aythya valisineria) and Redheads (A. americana). The larger Mute Swan may also compete with native Tundra Swans, recently brought back from near extinction, for food and shelter in winter. Aggression on nesting territories has been directed against breeding Canada Geese (Branta canadensis), Mallards (Anas platyrhynchos), and American Black Ducks (Anas ubripes). In Maryland, molting mute swans occupied a beach that was the last nesting area in the state for two state-threatened birds, the Black Skimmer (Rynchops niger) and the Least Tern (Sterna antilarium). The loafing swans trampled eggs and nestlings on the beach, leading to the abandonment of the area by both skimmers and terns for three seasons. Swans are very aggressive toward people, pets, and other waterfowl. They can inflict serious damage with their wings and can prevent recreational use of some shorelines. Disturbance of SAV by swans can limit crabbing and fishing activities. Together with other waterfowl that defecate in water, flocks of Mute Swans contribute to degraded water quality and an increased coliform bacteria count. Cranberry farmers in New Jersey and Massachusetts complain that swans get into their bogs and uproot cranberry plants as they browse other submerged aquatic plants. Management. In 2001, Mute Swans became a protected species under the Migratory Bird Treaty Act. The U.S. Fish and Wildlife Service (USFWS) received the authority for managing the birds. In 2002, the USFWS issued depredation permits to states for Mute Swan

256 n VERTEBRATES (BIRDS) population control; and in 2003, it established the Atlantic Flyway Mute Swan Management Plan, which encourages states to develop and implement location-specific management plans. The chief means of controlling Mute Swans is by the labor-intensive practice of addling eggs. Eggs are coated with oil to suffocate the embryos with the adults unaware of any disturbance to their clutch. Trapping and relocating or killing adults are other population control measures. A hunting season could be a viable option; swans were originally domesticated in Western Europe for food. Several states prohibit the establishment of new populations by outlawing the sale or importation of birds and requiring that those already owned be pinioned. Every three years, extant populations in the Atlantic Flyway are monitored by air in midsummer, when native swans and Snow Geese are in the tundra.

Selected References Delany, Simon. “The Mute Swan in Europe—a Preliminary Assessment of Numbers, Distribution and Potential Risks in Dissemination of HPAI–H5N1.” Wetlands International, Feb. 14, 2006. http:// global.wetlands.org/LinkClick.aspx?fileticket=0hONijRYbSs%3D&tabid=56. Ivory, A. “Cygnus olor.” Animal Diversity Web, University of Michigan Museum of Zoology, 2002. http://animaldiversity.ummz.umich.edu/site/accounts/information/Cygnus_olor.html. “Mute Swan.” New York State Department of Environmental Conservation, Fish, Wildlife and Marine Resources, n.d. http://www.dec.ny.gov/animals/7076.html. “Mute Swan Cygnus olor.” Invasive Species in the Chesapeake Watershed. Summary, Chesapeake Bay Program, 2002. http://www.mdsg.umd.edu/issues/restoration/non-natives/workshop/mute _swan.html. “Mute Swan Management Plan.” State of Rhode Island and Providence Plantations, Department of Environmental Management, Division of Fish and Wildlife, 2006. http://www.dem.ri.gov/ programs/bnatres/fishwild/pdf/muswan07.pdf.

n Rock Pigeon Also known as: Common Pigeon, Feral Pigeon, Rock Dove Scientific name: Columba livia Family: Columbidae Native Range. Europe, North Africa, southwestern Asia. At their maximum predomestication range, wild Rock Pigeons could be found from the Faeroe Islands and southwest Norway south through the United Kingdom and coastal France, to Spain and Portugal and eastward along the shores of the Mediterranean in southern Europe and North Africa. Its range also extended eastward across inland Europe into Russia, the Middle East, and India and Nepal. Its natural habitat was cliffs, usually along coasts, where it nested in caves and on ledges. Rock Pigeons were domesticated more than 5,000 years ago in the eastern Mediterranean, and since then, feral pigeons have lived close to people in urban and agricultural settlements. Most northern European populations of wild pigeons were driven to extinction by overhunting or by genetic dilution from feral birds. Distribution in the United States. Rock Pigeons are common birds, especially in cities, throughout the United States and in Puerto Rico. Description. Rock Pigeons are medium-sized birds with small round heads and large chests. They are 12–13 in. (30–35 cm) long and have a wingspan of about 25 in. (62–68 cm). When they walk, their heads bob forward and backward. The plumage is extremely

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varied, a product of their domestication. Among the two dozen well-recognized colors and patterns are those named blue-bar or “wild type,” blue checker, blue-T, dark (melanistic) checker, spread, white, pied, and Ash red variants. The wild type is a bluish-gray body with a dark head. Iridescent feathers of blue, green, and purple circle the neck. The rump is white. Two black wing bars mark the folded wing, and a black band occurs on the end of the tail. The eyes are reddish, and the feet pink. A white cere or fleshy swelling appears at the top of the short beak. Females tend to select mates with a pattern different from their own and so perpetuate the variety of phenotypes in a population. There also tend to be geographic trends in color: city populations tend to have more checker and spread birds than rural populations (except in Honolulu, where 80% of the pigeons are white); and pigeons with red plumage are more frequently encountered in the American Southwest than in Top: The wild Rock Pigeon was a native species from Iberia to India and northern and eastern states. in mountainous areas of North Africa, where it inhabited cliffs. Pigeons are strong, agile Domesticated for more than 5,000 years and probably mixed with feral flyers with pointed wings simi- stock for the same amount of time, the true native range is uncertain. lar to falcons. When they glide, (Adapted from Kravtchenko, Viktor. “Columba livia distribution map.” the wings are held in a V. They http://en.wikipedia.org/wiki/File:Columba_livia_distribution_map.png.) Bottom: Rock Pigeons are common birds in cities and other humanappear tame and often forage modified habitats in all 50 states and Puerto Rico. and roost in flocks. Rock Pigeons produce a cooing sound, but this call is mainly heard when they are on their nests or during courtship. Related or Similar Species. The native Band-tailed Pigeon (Patagioenas fasciata) inhabits oak and pine woodlands in California and parts of Arizona and New Mexico. It will frequent waterholes, but is not a city bird. Another native pigeon, the White-crowned Pigeon (Patagioenas leucocephala), breeds in mangroves and forages in inland hardwood forests. In the United States, it is restricted to the southern tip of Florida and the Florida Keys and is also found in Puerto Rico. Introduction History. Domestic pigeons were once important sources of meat and eggs, and people carried them around the world. The first captive birds came to North America

258 n VERTEBRATES (BIRDS) in 1606 with the settlement of Port Royal in Nova Scotia. The first pigeons to arrive in what is now the United States came with the settlers of Jamestown, Virginia, in 1607. All Rock Pigeons living free in the United States derive from escapes of domestic birds. Habitat. Rock Pigeons are feral birds found in proximity to humans in farms, towns, and cities. They require structures with ledges for nesting, loafing, and roosting; and most buildings serve well as surroRock pigeons are familiar denizens of urban landscapes. The plumage of gate cliffs and caves. Nests will these feral birds is extemely varied, a product of domestication. (Jaimaa/ be built wherever there is a dark Shutterstock.) opening, on a ledge on a skyscraper, in the rafters of an abandoned building, or under a bridge. Diet. Rock Pigeons forage on the ground, mainly for medium-sized seeds. Preferences include dried peas, wheat, oats, barley, millet, and maize. In urban settings, they also consume grass seed, berries, bread crumbs, popcorn, and other particles of discarded food. Life History. Pigeons in cities may breed all year. Most nesting, however, occurs between March and October. Males will fluff their feathers and bow-coo in courtship of females at any time. The pair will mate for life. The male selects the nesting site, and the pair constructs a crude nest. The male brings nesting materials to the female, and she tucks the straw, twigs, and feathers he brings around her body. The female typically lays two white eggs 40 hours apart. The eggs hatch asynchronously 17–20 days later. The first egg hatches about a day before the second. Male offspring are larger than females and often the first to hatch. The larger nestling has a distinct advantage over its smaller nest mate, which will die in years of food shortages. The younger sibling can be viewed as insurance for the parents if something should happen to the first one, and in good years, both will survive and fledge. For the first 4–5 days, nestlings are fed pigeon “milk,” a cheesy secretion of the crops of both parents that is rich in protein and fats. The crop milk is regurgitated to the young birds and ceases to be produced after 10 days. As the pigeon milk supply declines, more and more seeds are given to the squabs (birds 1–30 days old). Squabs leave the nest in 4–5 weeks and are fully independent when about 7 weeks old. A pair of pigeons may breed several times a year, sometimes constructing new nests on top of old ones encrusted with droppings from previous broods. A typical pair in Kansas produces 10 squabs a year from an average of 6.5 nests. Young pigeons are able to breed at six months of age. The large reproductive potential of feral pigeons is a legacy of their history as a domesticated species. Impacts. Feral pigeons are no longer considered an agricultural pest in the United States. In cities, they can be a nuisance, littering building lofts, fac¸ades, and sidewalks with their droppings and nesting materials. Their dung can harbor the fungus Histoplasma capsulatum; cleanup programs aimed at getting rid of pigeon and starling droppings have caused histoplasmosis infections in the lungs of humans in Arkansas, Ohio, Missouri, and Wisconsin.

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Nonetheless, many people derive pleasure from feeding pigeons in urban parks and at feeders, and eradication programs are few. Management. The most effective way to control feral pigeon populations is to reduce or eliminate food sources and barricade nesting and roosting sites. Cleaning up vacant lots and reducing litter on urban streets and in parks will help with the former, as will using feeders that minimize the amount of seed that scatters onto the ground. Netting, metal spikes on ledges or other perches, and electric exclusion fences can help with the latter.

Selected References Hetmanski, Tomasz, and Anna Jarosiewicz. “Plumage Polymorphism and Breeding Parameters of Various Feral Pigeon (Columba livia Gm.) Morphs in Urban Area.” Gandsk, north Poland. Polish Journal of Ecology 56(4): 683–91, 2008. Available online at http://www.pol.j.ecol.cbe-pan.pl/ article/ab56_4_12.pdf. Johnston, Richard F., and Marian Janiga. Feral Pigeons. New York: Oxford University Press, 1995. “Rock Pigeons.” AvianWeb and Wikipedia, 2006. http://www.avianweb.com/rockpigeons.html. Roof, J. “Columba livia.” Animal Diversity Web, University of Michigan Museum of Zoology, 2001. http://animaldiversity.ummz.umich.edu/site/accounts/information/Columba_livia.html. Youth, Howard. “Pigeons: Masters of Pomp and Circumstance.” Zoogoer, 276. Friends of the National Zoo, 1998. http://nationalzoo.si.edu/Publications/ZooGoer/1998/6/pigeons.cfm.

n Mammals n Black Rat Also known as: House rat, roof rat, ship rat Scientific name: Rattus rattus Family: Muridae Native Range. Most authorities agree that black rats originated on the Indian subcontinent and possibly in neighboring areas of Southeast Asia. They have been so long associated with humans, migrating with people around the world, that it is difficult to know their origins with any certainty. Distribution in the United States. Currently, the black rat is most common in the southern United States, although before the introduction of the Norway rat in the eighteenth century, it was the common rat in towns and on farms in the Northeast. In the lower 48 states, it is largely found in seaports, but small, isolated populations do occur inland. Larger populations are known from California’s Central Valley and along the Pacific coast north into the Puget Sound region of Washington State. In the eastern United States, they are found from Norfolk, Virginia, south along the Atlantic coast and throughout the Gulf states. Black rats also occur in Hawai’i, where they live in moist natural forests. Description. The black rat is slender and has a tail longer than its head-body length. The tail is used for balance, making this rat a most agile climber on overhead wires and tree limbs. Its ears are relatively large and hairless. The body may be black all over, or the back may be brown to gray and the underside a lighter tone. The tail is hairless, scaly, and uniformly colored. Head-body length ranges from 6 to 8 in. (160–220 mm) and tail length from 8.5 to 10 in. (190–240 mm). Black rats weigh 5–10 oz. (140–280 g). Males are larger than females.

260 n VERTEBRATES (MAMMALS) Related or Similar Species. The closely related Norway rat (see Mammals, Norway Rat) is larger and its tail is shorter than its head-body length. The ears are relatively small. Woodrats (Neotoma spp.) have white undersides. The rice rat (Oryzomys palustris) has small hairy ears; its gray back is streaked with black, and its belly and feet are whitish and its long tail is pale below. Introduction History. The black rat spread along the trade routes of Asia and Europe, entering the eastern Mediterranean in Roman times and Europe by early medieval times. It is the infamous carrier of the Black Death (bubonic plague) that ravaged Europe several times during the Middle Ages. In the 1500s, it arrived with Europeans in Central and South America. Black rats were aboard the earliest ships arriving at Jamestown, Virginia; Captain John Smith complained of thousands of rats devastating grain stores in 1612. They subTop: The Indian subcontinent is the most probable home of the black rat, sequently moved from port to but it may also have occurred originally in Southeast Asia. The original port and then dispersed inland source area is obscured by the animal’s long dispersal history in the wherever humans lived and company of humans. Bottom: Since the introduction of the Norway rat farmed. The invasion of the to the continental United States, the black rat has become almost Norway rat about the time of exclusively a resident of southern states, where it is found primarily in the American Revolution led to seaports. In Hawai’i, however, it is found in moist forests. (Adapted a range reduction among black from Marsh 2005.) rats in North America, as the larger newcomer replaced black rats in regions with more prolonged winters. Coastal and insular populations may be constantly replenished today as black rats continue to arrive on incoming vessels. Habitat. Black rats prefer warm climates and areas inhabited by people. However, their rarity in the more temperate regions of the United States may be due more to their displacement by the later-arriving Norway rat than to environmental conditions, as they were formerly common in towns and farms in New England and elsewhere in the northern United States. These rodents are agile climbers and often live in treetops in natural settings or the upper floors and attics and rafters of buildings everywhere from the inner city to small

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towns. The latter is particularly true where their range overlaps with Norway rats, which occupy cellars and lower floors. Black rats also commonly occupy ships, gaining access by climbing up ropes or stowing away in the cargo. While they may live in riparian vegetation, black rats rarely swim. Diet. Omnivores, these rodents prefer grains, nuts, and fruits, but also prey on invertebrates and the eggs and chicks of birds. They also like poultry and livestock feed and cat and dog food. Black rats will cache solid food to consume later and must drink water daily. Life History. These are social animals living in mixed groups of adult males and females. Nonetheless, one male is dominant, and usually two or three females are dominant to all others in the group except the dominant male. Males breed with more than one female and defend their territories and mates. In warm climates, breeding occurs all year; in more seasonal climates, breeding may peak in summer and fall. Nests are constructed in tree cavities, The agile black or roof rat has a tail longer than its head-body length. among palm leaves, in hedge- (Falcon Scallagrim/iStockPhoto.) rows, in protected niches in buildings, or in other dense cover. After a gestation period of 20–22 days, females give birth to 5–8 altricial pups. Their eyes open and pellage begins to show in about two weeks, at which time they begin to move around. They will be weaned in at 3–4 weeks, but stay at the nest until they reach adult size. They will be reproductively mature at 3–4 months of age. The young of the season leave the area when mature; it is unknown how far they disperse. Under prime conditions, a female will produce five litters a year. Average lifespan for a wild rat is about one year. Impacts. Black rats have been implicated, directly or indirectly, in the extinction of native species, particularly on islands. In Hawai’i they contributed to the extinction of some of the islands’ endemic honeycreepers (Drepaniidae) in the 1800s and now threaten the survival of seabirds such as Bonin Petrels (Pterodroma hypleuca) through predation on the birds’ eggs. Similar depredations on islands around the world led to their nomination as one of the 100 “World’s Worst” invaders by the IUCN/SSC Invasive Species Specialist Group.

262 n VERTEBRATES (MAMMALS) Apparent proof of the rat’s impact can be seen on Anacapa Island in the Channel Islands off California, where the rare Xantus’s Murrelet (Synthliboramphus hypoleucus) is increasing in numbers since the eradication of the black rat in 2000–2001. As a vector for dangerous human diseases, the black rat is infamous. In addition to bubonic plague, caused by the bacterium Yersinia pestis that is transmitted by rat fleas, black rats also carry leptospirosis, toxoplasmosis, trichinosis, and typhus. Damage to tree crops such as citrus, avocado, and some nuts is a problem in some places. Sugarcane is damaged where rats feed because they open stalks to insects and pathogens. Like their cousins the Norway rats, black rats are major pests in grain and other feed storage facilities, contaminating food with their urine and feces. In buildings, they will gnaw electrical wiring and damage insulation. In backyards, they will consume ornamental plants, fruits, and vegetables. Management. The best practice is to prevent the establishment of a rat colony in the first place. Rat-proofing roofs; clearing dense, overgrown shrubs and vines; eliminating water sources and removing pet food left outside; and securing food and feed in rat-proof containers are first lines of defense. Trapping and poisoning black rats can be problematic as they distrust new objects in their environment and will avoid them. Successful eradication programs on islands have relied on anticoagulant baits. Black rats are not a protected species and may be killed or captured at any time using mechanical or chemical means. However, the chemicals used must be registered for rat control by federal and state agencies and used in accordance with label directions.

Selected References “Black Rat, Rattus rattus.” eNature.com, 2007. http://www.enature.com/fieldguides/detail.asp ?recnum=MA0096. Gillespie, H., and P. Myers. “Rattus rattus.” Animal Diversity Web, University of Michigan Museum of Zoology, 2004. http://animaldiversity.ummz.umich.edu/site/accounts/information/Rattus _rattus.html. IUCN/SSC Invasive Species Specialist Group (ISSG). “Rattus rattus (Mammal).” ISSG Global Invasive Species Database, 2006. http://www.issg.org/database/species/ecology.asp?si=19. Marsh, Rex E. “Roof Rats.” Internet Center for Wildlife Damage Management, 2005. http://icwdm.org/ handbook/rodents/RoofRats.asp.

n Feral Burro Also known as: Wild donkey Scientific name: Equus asinus Family: Equidae Native Range. The ancestor of the burro, the African wild ass (Equus africanus), evolved in the deserts of eastern Egypt, Sudan, and the Horn of Africa. The domestic breeds, which were the founding stock for feral burros, were Spanish in origin and most probably came into the United States from Mexico. Distribution in the United States. Most feral burros are on public lands managed by the Bureau of Land Management (BLM) in Arizona, California, and Nevada. Almost half are located in the Lower Colorado River valley. A few small populations can be found in Oregon, Utah, and in Custer State Park, South Dakota.

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Description. The typical burro is gray with a white muzzle, white eye-rings, black shoulder cross and black leg barring. Many, however, are black or spotted (paint), and white individuals are not uncommon. Average shoulder height is 47 in. (120 cm). Their long ears are distinctive. Feral burros congregate in small groups with transient members. Groups generally consist of bachelor males or females and their immature offspring. Only mature jacks (males) are solitary. Introduction History. Most feral burros stem from domestic animals used by prospectors and miners during the western gold rushes of the nineteenth century. By the end of that century, the development of roads and railroads marked the obsolescence of pack animals, and the boom time of small-scale gold, silver, copper, and lead mining was largely over. Many burros were abandoned to fend for themselves at that time. Habitat. Feral burros thrive Top: Two subspecies of wild African asses occurred historically in the in warm desert habitats as long desert east of the Nile and in the Horn of Africa. They were likely first as permanent water sources are domesticated in Upper Egypt some time prior to 5,000 years ago. In the available. In spring and sum- colonial period, Spain was known for its fine breeds of domestic ass, mer, burros tend to congregate which were transported to its colonies in the New World. (Adapted from Woodward, S. L. “Feral burros of the Chemehuevi Mountains, in riparian habitats where shade California: The biogeography of a feral exotic.” PhD diss., University of and food are available; in winter, California, Los Angeles, 1976.) Bottom: The current range of freethey frequent interfluves where roaming feral burros in the United States consists mostly of desert areas annual forbs may be abundant. managed by the U.S. Bureau of Land Management. (Based on U.S. Diet. Burros are primarily Bureau of Land Management’s herd management areas maps and data.) browsers. In a study area along the Lower Colorado River in California, more than 60 percent of the diet of feral burros was comprised of desert shrubs such as palo verde (Cercidium floridanum), mesquite (Prosopis spp.), and arrowweed (Pulchea sericea). Thirty percent was composed of forbs, particularly winter annuals such as woolly plantain (Plantago insularis). Grasses were also consumed. Life History. Feral burros breed year round in warm deserts. The jenny (female) gives birth to a single foal, who accompanies her for a year or longer. Juvenile males typically leave

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A. The typical feral burro is gray with a white muzzle, white eye-rings, and black shoulder cross. However, black, white, and spotted individuals are not uncommon. (Chris Curtis/Shutterstock.) B. Most burros occur in the deserts bordering the lower Colorado River. (Susan Woodward.)

the mother when about one year of age and assemble in bachelor groups of varying size and membership. Occasionally, a juvenile female will tag along with a small bachelor group or single jack for a time. Mature jacks may or may not establish temporary territories near sources of water and attempt to breed with jennies passing through it. However, many breeding attempts also occur beyond the limits of the territory by non-territorial males. Females are sexually mature by 10 months, males by 12 months; but they usually do not breed successfully until older. Full physical growth is not achieved until about two years of age. Females come into estrous immediately after giving birth, but usually do not conceive at that time. Gestation lasts almost 12 months, and jennies may nurse their foal for up to a year. It is common for females to foal only once every two years even in optimal habitat. Lifespan may be up to 15 years. Impacts. Burros establish well-developed trails along the contours of desert slopes, which, along with their dust wallows, could accelerate erosion. Trampling can lead to compaction of desert soils and destruction of archeological sites. Feral burros could compete with desert bighorn sheep (Ovis canadensis nelsoni) for forage and water and could also compete with the federally threatened desert tortoise (Gopherus agassizii) for forage and crush its burrows. They are accused of fouling precious desert water holes with their feces; but domestic cattle are more likely perpetrators, since burros are loathe to get their feet wet. Management. The 1971 federal Wild Horse and Burro Act mandated that the BLM protect and manage feral burros on the public lands under their jurisdiction as living symbols

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of our national heritage. At that time, an estimate 14,400 burros roamed the deserts of the Southwest. Herd Management Areas were established, and appropriate population levels were determined for each managed population. Excess animals were removed and put up for adoption. Today an estimated 4,700 feral burros remain in a free-roaming state. Nearly half of these are in Arizona. The other half is nearly evenly divided between California and Nevada. To mitigate the potential impact of burros on bighorn sheep, water tanks have been established in some areas and fenced so as to permit sheep to enter but not burros. Feral burros are also managed on special sanctuaries or preserves. Many more are held in short-term corrals and long-term pastures awaiting adoption. Most feral burros have been removed from those national parks in which they once occurred under the National Park Service’s mandate to eliminate nonnative species. In 2010, the secretary of the interior announced plans to more aggressively use fertility control measures and manage sex ratios of free-roaming populations in the management of feral horse—and presumably feral burro—herds.

Selected References MacDonald, C. R. “Wild Burros of the American West: 2006 National Burro Status, A Critical Analysis of the Current Status of Wild Burros on Public Lands.” 2007. http://www.wildhorsepreservation .com/pdf/BurroAnalysis-2006-Public.pdf. “National Wild Horse and Burro Program.” Bureau of Land Management, 2010. http://www.blm.gov/ wo/st/en/prog/wild_horse_and_burro.html. Woodward, S. L. “The Social System of Feral Asses (Equus asinus).” Zeitshrift fur Tierpsychologie 49: 304–16, 1979. Woodward, S. L., and R. D. Ohmart. “Habitat Use and Fecal Analysis of Feral Burros (Equus asinus), Chemehuevi Mountains, California,” Journal of Range Management 29: 482–85, 1976.

n Feral Cat Also known as: Alley cat, house cat Scientific name: Felis silvestris catus Family: Felidae Native Range. The domestic cats from which feral cats derive were primarily European animals transported with colonists to North America and Hawai’i. Recent genetic studies point to the Near East as the site of the earliest domestication of the cat and its ancestor as the Near Eastern wildcat, F. s. lybica. The propensity of free-roaming cats to interbreed with wild cats has introduced genes from other subspecies of Felis silvestris, including the European wildcat (F. s. silvestris) and the Central Asian wildcat (F. s. ornata). Distribution in the United States. Throughout. Description. Feral cats are indistinguishable from domestic house pets and display a full range of coat patterns. After many generations in a free-roaming state, they tend to revert to the “wild type” tabby color pattern, with varying degrees of white on belly and chest. Adults have a shoulder height of 8–12 in. (20–30.5 cm) and weigh 3–8 lbs. (1.4–3.6 kg). Body length is 14–24 in. (35.5–60 cm); the long, flexible tail adds an additional 8–12 in. (20–30.5 cm). These agile predators have retractable claws, sharp teeth, long whiskers, and keen hearing and eyesight, including acute night vision.

266 n VERTEBRATES (MAMMALS) Related or Similar Species. Free-roaming but owned domestic cats are identical in appearance, although they tend to be tame. Bobcats (Lynx rufus) are twice the size and have black-tipped, stump tails. Introduction History. Domestic cats were first introduced to the mainland of the United States by European traders and colonists in the seventeenth century. They arrived in Hawai’i in the 1800s. Cats were commonly kept on sailing ships to kill vermin such as rats and mice. Before they became pampered companion animals, they were used as work animals to control rodent pests in barns and fields and were only loosely managed. Many undoubtedly escaped to a feral state. Feral cat populations continue to be supplemented by unneutered pets that wander off and produce litters in the wild. However, large numbers are the result of the deliberate abandonment of unwanted pets and litters of kittens. Often, wellTop: Cats were probably first domesticated in Mesopotamia. Their intentioned people release ancestors were the Near East subspecies of wildcat, Felis silvestris lybica. domesticated animals into the (Adapted from http://en.wikipedia.org/wiki/File:Wiki-Felis_sylvestris wild rather than subject them .png) Bottom: Feral cats are found in all 50 states and Puerto Rico. to the likelihood of euthanasia at animal shelters. The United States, a country where cats are the most popular household pet, has an estimated 30–60 million feral cats. Habitat. Feral cats are highly adaptable and occupy a wide variety of habitats and climate regions. They tend to congregate where food is readily available and shelter is nearby. Colonies may live in urban alleyways, near waste collection sites behind restaurants and fast food operations where food waste, as well as foraging rodents, may be abundant; in towns, where people often feed them; and on farms. They are also common on college campuses, at military bases, and in other places where the human population is transient and pet abandonment is frequent. Diet. Midsize carnivores, feral cats prey upon small mammals, birds, reptiles, amphibians, and insects.

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A. Feral cats are indistinguishable from house pets and display a full range of coat patterns. (Matt Valentine/ Shutterstock.) B. After many generations in a free-roaming state, feral cats tend to revert to the “wild type” tabby pattern. (Daz/Shutterstock.)

Life History. Feral cats are very prolific. Sexual maturity is achieved by females between 7 and 10 months of age and sometimes even younger. Gestation is 63–65 days. Reproduction can occur year round. A female typically produces three litters of 4–6 kittens a year. The young are weaned in 35–40 days. Life expectancy for a feral cat is only 2–3 years, compared with 10–20 years for a cat that is a household pet. Impacts. Cats, feral and free-roaming pets alike, are a major threat to wildlife because of the great numbers of small mammals, reptiles, and birds that they kill. The destruction of native birds often receives the most attention, but the number of small mammals such as shrews, chipmunks, and rabbits killed each year by cats is even greater and may reach more than a billion. A single cat may kill 100 or more small mammals and birds each year. While island populations of endemic species are most vulnerable to losses, the depredations occurring in suburban and urban “habitat islands” are significant. In Florida, cats are considered a major threat to several federally endangered small mammals, including the Key Largo cotton mouse (Peromyscus gossypinus allapaticola), rice rat (Oryzomys palustris natator), Key Largo woodrat (Neotoma floridana smalli), Lower Keys marsh rabbit (Sylvilagus palustris hefneri), Choctwhatchee beach mouse (Peromyscus polionotus allophrys), Perdido Key beach mouse (Peromyscus polionotus trissyllepsis), Anastasia Island beach mouse (Peromyscus polionotus phasma), and Southeastern beach mouse (Peromyscus polionotus niveiventris). They are also known to prey upon federally listed birds such as Roseate Tern (Sterna dougallii), Least Tern (Sternula antillarum), and Florida Scrubjay (Aphelocoma coerulescens) and on green sea turtles. In Hawai’i, cat predation is one more factor pressing endangered birds—such as the Hawaiian Crow or ‘Alala¯ (Corvus hawaiiensis); Hawaiian Goose or Ne¯ne¯ (Branta sandvicensis); Palila (Loxioides bailleui), a Hawaiian honeycreeper; and Hawaiian Petrel or ‘Ua’u (Pterodroma sandwichensis)—toward extinction.

268 n VERTEBRATES (MAMMALS) Feral cats can be reservoirs for feline diseases such as feline leukemia and FIV, threatening native bobcats and mountain lions as well as domestic house cats. They also can transmit rabies to pets and humans and may carry parasites such as Toxoplasmosis gondii, roundworm, and hookworm. Fleas in cat colonies can spread to nearby human dwellings and workplaces. Nominated by the IUCN as among “100 of the World’s Worst” invaders, feral cats are notorious as introduced predators on islands all over the world. Management. Feral cat control is an emotionally charged issue. Animal welfare advocates and conservationists tend to have different goals and therefore different approaches to the problem. Humane organizations are interested in the well-being of the cats; conservationists focus on halting depredation of native fauna. Trap-neuter-release (TNR) programs tend to be least controversial in most communities, but do not prevent the ecological damage a dense colony of carnivores can impose on native small animal populations. While reducing the number of breeding adults in a cat colony should over time reduce the feral population, recruitment of new members will continue as long as people abandon or fail to sterilize their pets. Cats are thought of as solitary, but they are only slightly territorial and, where food is abundant, will congregate in large numbers. Permanent removal of animals from a feral cat colony tends to open space for new arrivals. A sterilized cat released back to the colony, on the other hand, creates competition for food and shelter and may actually increase the mortality of kittens born into a feral state. Many feral cat colonies are managed and fed by volunteers, who capture, spay, and vaccinate new strays entering the population. Kittens may be removed, tamed, and put up for adoption. Nonetheless, small mammals, birds, and reptiles will continue to be killed. As every cat owner knows, even a well-fed cat kills. On some islands, eradication of feral colonies by trapping and euthanasia may be possible, but on the mainland, the ecological impacts of cats will continue as long as millions of pet cats are neither sterilized nor confined, and as long as people feed and care for strays.

Selected References Driscoll, Carlos A., et al. “The Near Eastern Origin of Cat Domestication.” Science 37: 519–23, 2007. LaBruna, Danielle. “Domestic Cat (Felis catus).” Introduced Species Summary Project, Columbia University, 2001. http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/inv_spp_summ/ Felis_catus.html. Longcore, Travis, Catherine Rich, and Lauren M. Sullivan. “Critical Assessment of Claims Regarding Management of Feral Cats by Trap-Neuter-Return.” Conservation Biology 23: 887–94, 2009. Masterson, J. “Felis catus, Feral House Cat.” Smithsonian Marine Station at Fort Pierce, 2007. http:// www.sms.si.edu/IRLspec/Felis_catus.htm. Verdon, Daniel R. “Feral Cats: Problems Extend to Wildlife Species, Ecologists Say.” DVM Newsmagazine, 2002. http://veterinarynews.dvm360.com/dvm/article/articleDetail.jsp ?id=31506&sk=&date=&&pageID=1.

n Feral Goat Scientific name: Capra hircus Synonym: Capra aegagrus hircus Family: Bovidae Native Range. Goats were first domesticated in the Zagros Mountains region of western Iran. Most island populations of feral goats in the United States likely derived from Iberian domestic breeds.

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Distribution in the United States. Invasive populations of feral goats are or were found in the Channel Islands of California and all the major islands of Hawai’i. Feral goats also exist on the island of Mona off Puerto Rico. Small populations of feral goats descended from escaped or abandoned livestock are found in isolated areas of the mainland United States (e.g., in California foothill habitats), but generally are not considered a problem because their numbers are held in check by predation and hunting. Description. San Clemente Island (California) goats are the best-described population. These animals adapted to an island environment over several hundred years in part by becoming relatively small and fine-boned. They are frequently described as deer-like and have a shoulder height of 21.5–29.5 in. (55–75 cm)—only slightly larger than dwarf breeds of domestic goats. Both males and females possess horns that spi- Top: The wild ancestor of domestic goats, Capra aegagrus, is native to the ral upward and outward. The mountains of western Iran, where domestication seems to have first taken males have heavier horns than place. (Adapted from Altaileopard, http://commons.wikipedia.org/wiki/ females and also have beards. File:Capra_aegragus_map.png.) Bottom: Feral goats are notorious Before extensive culling and invaders on islands. Today they remain on the Hawaiian Islands and on removal of goats to the main- Mona Island, Puerto Rico. land (see Management below), San Clemente Island goats displayed a variety of coat colors; today, they are mostly red or brown with black markings, especially on the head and forelegs. Feral populations usually assemble in herds of 5–20 animals. Herds may consist of mixed age and sex groups, all-male groups, or females and their young. Related or Similar Species. Goats are often confused with sheep. An easy way to tell them apart is to look at the tails: goats’ tails are held up, while sheep tails droop downward. Introduction History. Early Spanish and Portuguese explorers frequently dropped goats off on islands around the world to run wild and breed in order to serve as a meat supply for sailors arriving in the future. It has long been believed that the goats on the Channel Islands of California were introduced in this manner, but later supplemented by stock from

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A. Feral goats on Mauna Loa, Hawai’i, in the 1970s. (National Park Service.) B. Slopes on Santa Catalina Island in the Channel Islands of California were deeply gullied and overgrown with prickly pear cactus as a consequence of overgrazing by feral goats when this photo was taken in the late 1970s. (Susan Woodward.)

California’s Spanish missions and later still by farmers living on the islands. Recent genetic analysis of San Clemente goats, transplanted to that island from Santa Catalina in 1875, indicated that the island goats were not Spanish in origin, but a genetically distinct breed. Captain James Cook brought the first goats to Hawai’i in 1778. Habitat. Goats are hardy animals and adapt to a variety of habitat types. In California, feral goats subsist in Mediterranean scrub habitats, valley foothill hardwood, and valley foothill hardwood–conifer woodlands. They seek shelter on steep slopes and rock outcrops. In Hawai’i, they live from sea level to high alpine habitats with distinct dry seasons and prefer rocky slopes and open lava fields. A population on an island off South Carolina adapted to a hot, humid, and swampy environment. Diet. Goats are browsing animals and thrive on brush and other coarse vegetation unpalatable to sheep and cattle. They also consume grasses. Life History. Dominant males breed with estrous females serially. Gestation lasts 147– 155 days, after which time 1–3 precocial young are born. Twinning is common. Sexual maturity in both sexes may be reached by six months and definitely by one year of age. They may breed twice a year under favorable conditions. Impacts. Severe overgrazing by feral goats on islands can leave areas essentially devoid of vegetation. Not only are endemic plant species threatened in this manner, but the removal of food and cover endangers native island birds and other animals as well. In less severe situations, vegetation structure and species composition can be altered. Soil erosion and downslope sedimentation are other consequences of unmanaged browsing by goats. Ecosystem degradation and loss of biodiversity are potential outcomes. Management. On both the Channel Islands and in Hawai’i, hunting was tried as a way to reduce feral goat populations without success. Reports from Hawai’i Volcanoes National Park, for example, indicate that 70,000 goats were removed between 1920 and 1970, but the goat population remained high. On San Clemente Island, owned by the U.S. Navy since 1934, systematic removal of goats began in 1972. Large numbers were driven into traps with net-wing fences and killed. Some 16,000 animals were removed between 1975 and 1979 and another 8,000 between 1979 and 1982, when an estimated 4,000 goats still roamed the island. Goats have since been completely eradicated from Lana’i Island, Hawai’i, and San Clemente Island using a combination of techniques including aerial hunting from helicopters; specially trained goat-hunting dogs to flush out remaining survivors; and “Judas goats,”

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sterilized goats outfitted with radio-transmitters that seek out herds to join and thus detect any goats missed by other methods. When the navy proposed shooting goats from helicopters to eliminate them from San Clemente, the Fund for Animals, an animal welfare group, stepped in and live-trapped the remaining animals with nets and helicopters and removed some 3,000 goats to the mainland, where most were sterilized and put up for adoption. A few animals were not neutered and formed the base of a new breed of domestic goat, the San Clemente Goat. These hardy, disease- and parasite-resistant animals are used as meat animals and also as pets. On Santa Catalina Island (California) and parts of Hawai’i, exclusion fencing has kept feral goats out of localized areas and allowed the regeneration of native plants.

Selected References “Capra hircus.” Introduced Species in Hawaii. Senior Seminar Biology Department, Earlham College, 2002. Coblentz, Bruce. “Capra hircus (Mammal).” USA and IUCN/SSC Invasive Species Specialist Group (ISSG). ISSG Global Invasive Species Database, 2008. http://www.issg.org/database/species/ ecology.asp?si=40. Edmundson, Leslie. “San Clemente.” Breeds of Livestock. Oklahoma State University, 1997. http:// www.ansi.okstate.edu/breeds/goats/sanclemente/index.htm. “San Clemente Goat.” American Livestock Breeds Conservancy, n.d. http://www.albc-usa.org/cpl/ sanclementegoat.html.

n Feral Horse Also known as: Wild horse, mustang; Banker horse Scientific name: Equus caballus Family: Equidae Native Range. Europe. Feral horses descend from domestic horses bred in Spain and parts of northwestern Europe. The earliest domesticated horses have been traced to the steppes of Kazakhstan and Ukraine, but Iberian wild horses may have contributed to the development of European breeds. Distribution in the United States. Populations of free-roaming horses occur in 10 western states, primarily on the public lands administered by the Bureau of Land Management. In addition, a population is maintained in Theodore Roosevelt National Park, North Dakota. Other herds are found at several sites along the Atlantic coast, including North Carolina’s Outer Banks and Assateague National Seashore and Chincoteague National Wildlife Refuge in Virginia. About half all feral horses reside in Nevada. Description. Feral horses are indistinguishable from domestic horses, although a few populations have been isolated long enough to preserve or evolve unique genetic information. Western horses generally stand 14–15 hands (4.75–5 ft. or 1.4–1.5 m); males weigh 795–860 lbs. (360–390 kg) and females 595–750 lbs. (270–340 kg). Assateague ponies and other eastern insular horses tend to be smaller, with shoulder heights seldom more than 13 hands (4.3 ft. or 1.3 m). Feral horses come in all colors and patterns, including solid colors ranging from black to cream, paints of every type, and leopards. Of genetic significance are the few herds of pure Spanish mustangs descending from the earliest domestic horses brought to the Americas. These horses have short, straight backs and deep, narrow chests that are V-shaped when viewed from the front. The croup (rump)

272 n VERTEBRATES (MAMMALS) is low, and the tail set low. They usually have straight to concave foreheads and convex noses. Examples include the Kiger mustangs in southeastern Oregon and the Cerbat mustangs found near Kingman, Arizona. The feral horses of Theodore Roosevelt resemble horse types common in the nineteenth century, but rare today. They have large heads and short backs and are frequently blue or red roans with “bald” or “apron” (white) faces and white patches on their sides. Related or Similar Species. Feral horses are generally indistinguishable from domestic horses. In western states, ranchers and Native Americans often allow their horses to run free when they are not using them, and these animals could easily be mistaken for feral horses. Introduction History. Christopher Columbus, on his second voyage to the New World in 1493, brought the first horses to the Americas when he landed them on Hispaniola. From that Top: The wild ancestor of the domestic horse was native to the steppes of Caribbean island, Spanish conEurasia, but it is now extinct in the wild. Bottom: Free-roaming feral quistadors introduced them to horses still live in the deserts and grasslands of 10 western states and a mainland North America in the few islands off the East Coast of the United States. (Based on U.S. early 1500s. Spanish horses Bureau of Land Management’s herd management areas maps and data spread northward through and other reported occurrences.) Mexico along the chain of missions set up by the Spanish. Native Americans raided the missions and settlements of the frontier, stole the horses, and became adept horsemen, warriors, and bison hunters. They exchanged and stole horses from other tribes, effectively spreading the animal throughout the continent. Some groups bred horses and developed distinctive breeds, such as the original Appaloosa. Other Spanish horses escaped from military outposts, where stallions were used as cavalry mounts. Large herds of semidomesticated horses developed on the Great Plains, their numbers and genes added to when European settlers with breeds from Western Europe pushed westward from the Atlantic coast of the United States. Herds of wild horses from east of the Mississippi were displaced westward with settlement. French breeds moved south and west from the Detroit region and north from the New Orleans colony. The U.S. Cavalry in the late

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1880s and early 1900s introduced old-style East Friesian blood to the mix. These draft horses were preferred for pulling artillery and heavy wagons; any that escaped would have joined the herds of feral horses roaming the Plains. Settlers lost horses when wild stallions broke through fences and liberated mares. Furthermore, it was common practice to let horses roam freely on the range until needed for work on ranches. Many likely escaped captivity and added to the feral herds. Wild horses existed in the Feral horses are generally indistinguishable from the domestic horses badlands of North Dakota when from which they descend. However, a few populations have been isolated long enough to preserve or develop unique genetic information. Theodore Roosevelt visited in (Robert Broadhead/Shutterstock.) the 1880s. He recognized them as escapes from nearby ranches or Indian reservations, and many carried brands. Most horses were removed from the area in 1954, a few years after the national park was established. A few small bands eluded capture and formed the core of the current herd managed by the National Park Service. The twentieth century saw the value of free-roaming horses decline as ranching and other interests grew, and many were shot or taken to slaughterhouses. Populations declined to such an extent that some feared the feral horse was headed for extinction. The mustang became celebrated by some as a romantic symbol of the Old West and its preservation demanded. A successful campaign initiated by “Wild Horse Annie” (Velma B. Johnston), who was aided by the letter-writing of schoolchildren across the country, resulted in a federal law to save the wild horse, the Wild Free-Roaming Horse and Burro Act, passed in 1971. Responsibility for managing the herds remaining on public lands fell to the Bureau of Land Management (BLM); the U.S. Forest Service gained jurisdiction over horses in national forests and grasslands. Under the protection of these agencies, feral horse populations began to grow again. In 2010, BLM estimated some 33,700 horses were on the rangelands they manage. In their evolutionary history, horses evolved in North America and crossed the Bering Land Bridge into Eurasia during the Pleistocene Epoch. They subsequently became extinct in North America 11,000–13,000 years ago, but were domesticated in Ukraine about 5,000 years ago. Horses were reintroduced—as domestic animals—by the Spanish early in the sixteenth century. The origin of the species on this continent has led some to propose that feral horses are native, not exotic species and that they are part of the natural heritage of the West. Habitat. In the West, feral horses generally inhabit open shrublands and woodlands in arid and semiarid regions. Optimal rangelands have grassy areas and riparian zones. On the offshore islands of the Atlantic coast, feral horses are associated with salt marshes. Diet. On western ranges, feral horses prefer grasses, forbs, and sedges but also browse shrubs such as shadscale saltbush (Atriplex confertifolia), sagebrush (Artemesia tridentata),

274 n VERTEBRATES (MAMMALS) and rabbitbrush (Chrysothamnus nauseosus). Assateague ponies graze preferentially on saltmarsh cordgrass (Spartina alterniflora), but will eat American beach grass (Ammophila breviligulata) and three-square rush (Scirpus americanus); they also browse woody plants. Life History. Most feral horses live in small, stable social groups of 5–15 animals. A band consists of a mature stallion and his harem, a group of 4–6 mares and their younger offspring. Sometimes a subdominant male also is part of the band. The group maintains a strict social hierarchy and often roams in an established territory. The mares will stay together even when the stallion is lost. Young stallions that have yet to acquire harems form bachelor herds. Old stallions that have lost their harems to younger males are usually the only solitary animals. The harem forms the breeding unit. Mating may occur year round but peaks during the foaling season, which is typically early spring. Usually a mare produces a foal every other year after a gestation period of about 340 days. When a mare is ready to foal, she temporarily leaves the harem and gives birth to a single offspring. The newborn can run and swim shortly after birth; and its mother brings it into the band a few hours later. The foal will continue to nurse until its mother is about to give birth again. Both fillies and colts are driven from the band when they reach sexual maturity around 2–3 years of age. The young mares will be collected into an existing or new harem by a stallion that is not their father. Young males will form into bachelor groups until such time as they can acquire mares of their own either by successfully challenging an aging stallion or by assembling a group of mares through stealth or upon the death of another male. Mature mares rarely move to another band. In the absence of natural predators and on good range, feral horse populations may grow rapidly, doubling in numbers in four years. Recruitment rates are especially high after major population reductions due to severe winter weather or roundups. Impacts. It is difficult to assess the real impacts of feral horses on native ecosystems because of the high degree of emotion surrounding the issue of their role on western rangelands. Apparently from 1600 to 1850, vast herds of horses occurred throughout the Great Plains, where they had transformed life for the Plains Indians. They shared the range with bison, pronghorn, elk, and mule deer. Extermination of horses accompanied the campaign to remove Native Americans from the West and also the development of modern cattle ranching. Although free-roaming horses were captured to become cow ponies and saddle horses, cattlemen more and more regarded them as nuisances that may lure away their domestic horses and compete with cattle for forage and water. Scientific studies reveal a dietary overlap of 80 percent or higher between feral horses and cows, both species of which are predominantly grazers. Since horses also browse, they are actually better suited to much western rangeland than are cattle; but Americans do not consume horsemeat, so the argument that horses should replace cattle is moot. With respect to impacts on other animals, comparatively little research has been conducted. Their diets do not seem to overlap significantly with deer, elk, or pronghorn, all of which are primarily browsers. Potentially, horses trample the nests of ground-dwelling birds. Reptile diversity and abundance may be reduced in areas occupied by feral horses. On well-managed ranges, plant diversity has been shown to increase with a variety of large grazing and browsing mammals, including feral horses, present. Greater abundance and diversity of large vertebrates occurred where horse droppings accumulated and soil was intermediately disturbed in California’s Anza-Borrego State Park. Trampling of vegetation and compacting of soils on trails made by horses could be localized problems and could accelerate soil erosion. Management. Feral horses are federally protected under the 1971 Wild Free-Roaming Horse and Burro Act. The law is administered by the BLM (Department of the Interior) and the U.S. Forest Service (Department of Agriculture). Shooting or poisoning feral horses in the wild

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became a federal crime. When BLM assumed authority for feral horses, an estimated 17,300 mustangs roamed western rangelands. In 2010, the number was estimated to be 33,700. As populations grew in the 1970s, amendments to the law in 1976, 1978, 1996, and 2004 mandated management of herds in such a way as to sustain their habitats and authorized humane removal of excess animals from the public lands. The 1976 Federal Land Policy and Management Act included feral horse management as part of BLM’s and the Forest Service’s multiple-use missions that require managing public lands for recreation, livestock grazing, mineral and energy production, and the conservation of natural, historical, and cultural resources. Feral horses are considered part of our national heritage. Appropriate Management Levels (AMLs) have been determined for the 201 Herd Management Areas designated by the BLM and the 37 that it comanages with the U.S. Forest Service. Herd reductions to achieve these population sizes and to maintain them have relied largely upon roundups and selecting excess animals to be removed and put up for adoption. The roundups use helicopters and cowboys on horseback, and are expensive and dangerous to both the horses and their captors. The Adopt-A-Horse program began as a way to transition feral horses back to private ownership and domestic status. Since 1971, BLM has placed more than 225,000 horses and burros in private care. Horses that prove impossible to adopt are held in short-term holding pens and on long-term pastures. In May 2010, 10,700 feral horses (and burros) were in corrals and another 24,400 maintained on pastures in the Midwest. An estimated 33,700 were on BLM-managed range, whereas the total AML has been set at 26,582. Fertility control is now a viable practice to reduce herd growth rates. The administration of porcine zona pellucida vaccine (PZP), an immunocontraceptive, by dart guns in the field has proved to be a safe and effective means of population control in conjunction with removal and natural mortality. Currently, booster shots are required annually. In June 2010 the secretary of the interior proposed new solutions to wild horse management, which he deemed unsustainable for the horses, the habitat, and the taxpayer in its current form. In part, he advocated more aggressive use of fertility control measures and the establishment of new wild horse preserves across the country in order to showcase these animals to the American public and to enhance local economies through increased tourism.

Selected References “Colonial Spanish Horse.” American Livestock Breeds Conservancy, n.d. http://www.albc-usa.org/cpl/ colonialspanish.html. Sponenberg, D. P. “The Colonial Spanish Horse in the USA: History and Current Status.” Archivos de zootecnia 41(extra): 335–48, 1992. “Wild Horse and Burro Quick Facts.” U.S. Bureau of Land Management, 2010. http://www.blm.gov/ wo/st/en/prog/wild_horse_and_burro.html. “Wild Horse: Equus caballus.” Enature.com, 2007. http://www.enature.com/fieldguides/detail.asp ?recnum=MA0169. “Wild Horses.” Theodore Roosevelt National Park, n.d. http://www.theodore.roosevelt.national -park.com/nat.htm#wil.

n Feral Pig Also known as: Wild pigs, feral hog, feral swine, Pineywoods rooter, razorback; Eurasian or European wild boar, Russian wild boar Scientific name: Sus scrofa Family: Suidae

276 n VERTEBRATES (MAMMALS) Native Range. Europe. Feral hogs are descendents of domestic breeds originally brought to the United States from Europe. Recent genetic analysis suggests that these breeds arose from wild boars native to Europe. In addition to domestic breeds, some truly wild boars from Europe were deliberately released in several states as game animals. Distribution in the United States. Feral hogs are found primarily in the southern tier of states from California to North Carolina. Isolated populations are reported as far north as Wisconsin and New Hampshire. The greatest numbers occur in California, Florida, and Texas. Feral pigs inhabit all of the major islands of Hawai’i and occur on St. John in the Virgin Islands. Description. Three types of free-roaming pig occur in the United States: feral hogs derived from escaped or released domestic stock, European wild boars, and hybrids between them. Most are feral livestock. These medium-size, cloven-hoofed mammals have long, pointed heads and stocky bodies. Males and females are similar in appearance. Reflecting their domestic origins, feral pigs display a variety of coat colors and patterns, from solid black, brown, white, or red, to spotted with several colors, or belted with a wide pale band across the shoulders. Their coat is coarser; bristles tend to be longer than those of domestic pigs, but shorter than those of wild boars or hybrids. The tail is straighter than a domestic pig’s and never coiled. The flattened snout is flexible and elonTop: The wild boar, ancestor of domestic pigs, is widespread in Eurasia. gate. Total body length is 3.6– However, the domestic breeds that were brought to the United States and 4.9 ft. (1.1–1.5 m). The average that contributed to the feral pig gene pool seem to have descended only adult has a shoulder height of from European populations. (Range of wild boar adapted from about 3 ft. (1 m); males (boars) Altaileopard, http://en.wikipedia.org/wiki/File:Sus_scrofa_range_map.jpg. weigh on average 130 lbs. Source of domestic breeds based on Larson et al., “Worldwide (60 kg) and females (sows) Phylogeography of Wild Boar Reveals Multiple Centers of Pig about 110 lbs. (50 kg). Domestication.” Science 307: 1618–21, 2005.) Bottom: In the United States, feral pigs are found primarily in southern states and on all the major Maximum weight is probably islands of Hawai’i. (Adapted from “Feral/Wild Pigs: Potential Problems for about 300 lbs. (135 kg). Males have four very sharp tusks that Farmers and Hunters.” USDA Agricultural Bulletin No. 799, 2005.)

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continue to grow throughout the lifetime of the boar, although they usually break or wear down to lengths of approximately 5 in. (12.5 cm). The lower tusks are continually sharpened as they rub against the upper pair. Tusks are used to establish dominance among males and to defend against predators and other males. The shoulder skin of males thickens as they age into a shield, a product of both aging and fighting; it consists of tough scar tissue and cartilage. Some but not all feral piglets are striped, much like the piglets of wild boars. European wild boars are usually light brown or black with cream-colored tips on the bristles. The ends of these long stiff hairs are often frayed. The belly hairs are lighter and the legs, ears, and tail darker than the rest of the body. Long side whiskers develop and hairs on the back of the neck give them the razorback appearance. Purebreds have longer legs and snouts and relatively larger heads than a feral pig; they have little fat. Piglets are reddish with black, lengthwise stripes. Hybrids show characteristics of both parents. The length of the bristles is longer than in feral pigs, but shorter than in wild boars. The diameter of the bristle shaft, however, is smaller than either feral or wild pigs. Occasionally, truly enormous pigs are captured in the wild. The infamous “Hogzilla,” shot in Georgia in 2004 and estimated to have weighed some 800 lbs. (363 kg) and have had a total body length of 8 ft. (2.4 m), was determined by National Geographic researchers to be a hybrid between a domestic pig and a wild boar. Others are likely escaped or abandoned domestic pigs, which are often bred and fattened to weigh over 1,000 lbs. (454 kg). The presence of feral pigs can be determined by a variety of signs. Hog tracks are square with rounded, splayed toes. Their rooting is often extensive; it can reach depths of 3 ft. (1 m) and may leave a field looking like it has been plowed. Wallows are depressions formed when pigs roll in mud to protect their skin from sun and insects; they often fill with water. Rubs develop where pigs scratch against trees, fence posts, and rocks to remove external parasites, dried mud, and dead hair. Telltale bristles are often left behind. Related or Similar Species. In the southwestern states of Arizona, New Mexico, and southern Texas, there is a native pig-like animal, the collared peccary or javelina (Tayassu tajuca). These are not true pigs and not closely related to feral swine, but belong in a New World family of mammals, Tayassuidae. Peccaries are gray with a narrow white band around the shoulders, and smaller than a feral hog. They congregate in herds. Introduction History. The first domesticated pigs came to North America with early Spanish explorers in the sixteenth century. Two hundred pigs arrived in Florida in 1539 with Hernando de Soto as a walking larder to accompany his expedition through the Southeast. Native Americans as well as later European settlers in the Southeast used the descendents of these hogs, often keeping them under free-range conditions. In the early nineteenth century, Spanish hogs accompanied the southern Native American groups resettled by the U.S. government in the Oklahoma Territory. (The small, wattled Choctaw hog, with its fused toes that look like a mule’s hoof, is a pure Spanish breed and is still managed today as a freerange animal in Oklahoma.) Undoubtedly, many pigs escaped to live in a wild state from the time of de Soto onward. Hernando Cortes brought pigs to Mexico, and they spread north with colonizers, probably reaching Texas some 300 years ago. Many may have been abandoned when people left Texas during its war for independence from Mexico (1834–1835). In Hawai’i, small pigs of Asian descent were originally introduced by Polynesians around 400 AD, but were replaced by European breeds about 200 years ago. English settlers brought their own breeds to

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A. The coat and bristles of feral pigs tend to be longer and coarser than those of the domestic pigs from which they descend. Their piglets sometimes are reddish with lengthwise black stripes like those of wild boars. (Laurie L. Snidow/Shutterstock.) B. Some free-roaming pigs descend from wild European boars introduced as game animals. They have longer legs and snouts than a truly feral pig. (Alan Lucas/Shutterstock.)

North America beginning in the seventeenth century, and Americans developed new breeds, such as Duroc, Hereford, and Poland China. All these stock interbred in the free state to form the common, genetically mixed feral hog populations that roam the United States today. Free-roaming feral pigs have occurred in southern states for a long time. However, range expansions into Colorado, Illinois, Indiana, Kansas, Kentucky, Missouri, Nebraska, Nevada, Ohio, Oregon, and West Virginia occurred mostly in the last decade of the twentieth century. Many of these were deliberate introductions by hunting clubs or private landowners for sport hunting. In all locations, they have been successful invaders because of their high reproductive potential, improved disease control in domestic livestock, pasture improvements related to modern livestock grazing practices, and development of watering sources for domestic stock in arid lands. Pure European or Russian boars were first released in the late 1800s and early 1900s for sport hunting in New Hampshire, North Carolina, Missouri, Arkansas, and Tennessee. They were introduced to Texas with the same purpose in the 1930s. Habitat. Feral pigs are habitat generalists but prefer densely vegetated moist forests and bottomlands where they can find shelter and make wallows. Diet. Pigs are opportunistic omnivores. Their diet depends on seasonal and geographic availability and is dominated by plant matter. Pigs will consume grasses, forbs, roots and tubers, fruits, acorns, and nuts. They also eat fungi and live earthworms, mollusks, amphibians, reptiles, and birds as well as eggs, and also scavenge carrion. Life History. Feral pigs display several characteristics that reflect ancestral domestic breeds that were purposefully selected for fast growth and early maturation. After a gestation period of 115 days, feral sows generally farrow litters of 4–6 but, under prime conditions, may give birth to 10–12 young. (Wild boars usually have smaller litters, with 3–8 piglets being typical.) Some scientists consider pigs to be the most prolific large mammal on the planet. As a rule, a 1:1 sex ratio exists at birth. Some females have two litters a year, but most have only one. Although young may be born throughout the year, peak production occurs in early spring. Piglets weigh 1–2 lbs. (0.45–0.91 kg) at birth. Young are weaned at 3–4 months. Family groups or sounders composed of 1–3 sows and their offspring may

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contain three generations and 50 or more individuals; they are maintained until the young mature. Females may stay in the family group or leave with their sisters to form a new group. Males always leave the family group by 16 months of age. Adult males are solitary, traveling among sounders to breed. Feral pigs are sexually mature at 6 months, but many females do not mate until 10–12 months of age. Young males may be prevented from breeding by more dominant boars. Adult stature is attained by age 3. Average lifespan is 4–5 years, with a maximum of 8 years. Hunting is the primary cause of death in adults. Groups rather than individuals have home ranges, and they vary in size from several hundred to a few thousand acres depending upon habitat quality. Pigs tend to occupy different parts of the home range seasonally. The need to cope with heat dictates the location of summer home ranges near water and can result in nocturnal activity. Neither individuals nor sounders maintain territories within the home range. Impacts. Due to their rooting and trampling of vegetation, feral pigs and wild boars may be the most extreme vertebrate modifier of natural ecosystems in the United States. They disturb soil horizons and compact soil, decreasing water infiltration and increasing erosion. Soil erosion, along with contamination by bacteria from fecal deposits, can increase sedimentation and pollution in waterways; pig activity has been implicated in declining freshwater mussel and aquatic insect populations in some areas. Their feeding can alter plant species composition and plant community structure. Disturbance of the soil and herb layer allows invasive plants to spread by creating habitat in which weedy exotics generally outcompete native plants. Feral pigs certainly compete with native animals for food and other resources. This is particularly true of mast-eaters such as white-tailed deer (Odocoileus virginianus), Wild Turkey (Meleagris gallopavo), and squirrels. They may also negatively affect wildlife populations through predation, habitat destruction, and the spread of parasites and disease. On the Atlantic beaches of the Southeast, feral pigs are threatening the nesting success of several endangered sea turtles, including loggerhead (Caretta caretta), leatherback (Dermochelys coriacea), hawksbill (Eretmochelys imbricata), green (Chelonia mydas), and Kemp’s ridley (Lepidochelys kempii) turtles. In Great Smoky Mountains National Park, their destruction of the leaf litter reduces the habitat of redbacked voles (Myodes gapperi) and short-tailed shrews (Blarina brevicauda), while direct predation reduces populations of threatened red-cheek salamanders (Plethodon jordani) and Jones middle-toothed snail (Mesodon jonesianus). Tree ferns are a major part of the diet of feral pigs in Hawai’i, where they also eat other native trees and epiphytes and reduce vegetative cover. Feral hogs also facilitate the spread of the invasive strawberry guava (Psidium cattleianum; see Volume 2, Trees, Strawberry Guava), a plant threatening the survival of several native Hawaiian plants and animals. Ecological and economic damage to crops, timber, and pasture can also be significant; crop depredations alone have been estimated at $1.5 billion a year in the United States. The greatest impact is to hay, small grains, corn, and peanuts, although tree fruits, cotton, vegetables, and conifer seedlings are not immune. Feral pigs are known to prey upon lambs, kids, and newborn calves, attracted to birthing areas by afterbirth. Predation on animals is difficult to document, since feral pigs also scavenge carcasses left by other animals. When they do hunt for themselves, they typically kill their prey by biting and crushing the skull. However, since the entire carcass is usually eaten, little or no evidence is left to point to the actual killer. Feral pigs carry several parasites and disease. Among those that could affect humans are trichinosis, leptospirosis, toxoplasmosis, and brucellosis. Hunters should be careful handling live animals and carcasses, and all pig meat should be well cooked. Livestock diseases

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Ossabaw Island Hog

T

he feral hogs on Osssabaw Island, Georgia, have been isolated long enough to develop unique characteristics but also are the closest representative, genetically, of original Spanish stock. They are a rare resource for science and for future animal breeding. These small pigs are able to store huge amounts of fat to survive lean seasons, a biochemical adaptation analogous to non-insulin-dependent diabetes in humans, which makes them an excellent model for medical research. Natural selection has also left Ossabaw Island hogs tolerant of high amounts of salt in their diet. Animals removed from the island have served as founding stock for a newly domesticated Ossabaw hog breed, which appears well adapted to sustainable or pastured pork production. Feral hogs may no longer be taken from the island because some individuals have tested positive for pseudorabies and porcine vesicular stomatitis (PSV); their future as a feral population depends on management goals of the state of Georgia. Source: “Ossabaw Island Hog.” American Livestock Breeds Conservancy, n.d. http:// www.albc-usa.org/cpl/Ossabaw.html.

are also potentially harbored in feral pigs. Those of greatest concern currently are swine brucellosis (Brucella suis) and pseudorabies, a herpes virus not related to true rabies. Were footand-mouth disease to be reintroduced to the United States, feral pigs could become a reservoir for this highly infectious virus (Aphtae epizooticae) and make eradication difficult if not impossible. Swine brucellois is a disease of the reproductive tract that causes spontaneous abortions, stillbirths, and infertility in both male and female pigs. Pseudorabies, also known as “mad itch,” causes abortion and mummified fetuses in pregnant domestic sows and can be fatal in piglets less than a month old. In other livestock, pseudorabies is an infection of the central nervous system that causes loss of appetite, staggering, and spasms, and is almost always fatal. Its early symptoms include scratching and rubbing and biting that can result in self mutilation. The virus spreads from wild pigs to domestic pigs through venereal contact. The Invasive Species Specialist Group (ISSG) of the IUCN has nominated the feral pig as one of “100 of the World’s Worst” invasive species. Management. Management of feral hogs can be controversial when the interests of hunters conflict with those of agriculturalists and environmentalists. It is also extremely difficult to eradicate established populations because they are so prolific and so mobile. Hunting is the best means of controlling populations. Using specially trained tracking and catch dogs or mules and dogs are popular practices. Live-trapping is also used. Regulations for hunting feral hogs, operating hunting facilities, and importing feral hogs vary from state to state.

Selected References “Feral Pig Hunting Information.” Wisconsin Department of Natural Resources, 2008. http://dnr.wi.gov/ org/land/wildlife/HUNT/Pig/Pig_Hunting.htm. IUCN/SSC Invasive Species Specialist Group (ISSG). “Sus scrofa (mammal).” ISSG Global Invasive Species Database, 2008. http://www.issg.org/database/species/ecology.asp?si=73&fr=1&sts.

HOUSE MOUSE n 281 Stevens, Russell. “The Feral Hog in Oklahoma.” Samuel Roberts Noble Foundation, Inc., 1999. http:// www.noble.org/ag/wildlife/feralhogs/. Taylor, Rick. “The Feral Hog in Texas.” Texas Parks and Wildlife, 2003. http://www.tpwd.state.tx.us/ huntwild/wild/nuisance/feral_hogs/. West, B. C., A. L. Cooper, and J. B. Armstrong. “Managing Wild Pigs: A Technical Guide.” HumanWildlife Interactions Monograph 1: 1–55, 2009. Berryman Institute. http://www.berryman institute.org/pdf/managing-feral-pigs.pdf.

n House Mouse Scientific name: Mus musculus Family: Muridae Native Range. Most sources state Asia or, more specifically, Central Asia as the place of origin of this species, but recent genetic evidence suggests that the Indian subcontinent may have been the earliest center of radiation. Distribution in the United States. Throughout, including all Hawaiian islands, but absent from most of Alaska. Description. These small Old World mice have relatively large round ears and prominent black eyes. The fur is gray to brown, with the undersides either a lighter shade than the back or a buffy white. The feet are a drab buff color, and the tips of the toes are white. The long grayish-brown tail, close to half the total body length, is essentially hairless; although lighter on the underside, it is not distinctly bicolor. Unlike New World mice, the incisors are not grooved. Adult head-body length is about 3 in. (65–95 mm); the tail is 3–4 in. (60– 105 mm) long. Average adult weight is 0.5–0.8 oz. (17–25 g). The presence of their droppings often alerts people to their presence. Fecal pellets are 0.25 in. (6 mm) long and have longitudinal ridges and square ends. Related or Similar Species. New World mice that also may occupy dwellings and other buildings include deer mice (Peromyscus maniculatus) and white-footed mice (P. leucopus). Both of these rodents have white bellies, sharply demarcated from the darker back, and tails that are covered with hair and distinctly bicolor. The tail of the white-footed mouse is shorter than its head-body length. The incisors of both are grooved. Introduction History. The house mouse has long been associated with humans. The earliest evidence of its commensal relationship with people goes back to a Neolithic site in Turkey dated at 8,000 BP. It was able to spread from settlement to settlement across Asia with expanding Neolithic populations and later along trade routes into Europe, where two subspecies, M. m. musculus and M. m. domesticus, were found by 4,000 years ago. It was likely accidentally introduced into Florida by Spanish explorers in the early 1500s and came to what is now the northern United States with French fur traders and English settlers in the early 1600s. This small rodent easily stows away in tiny spaces and in grain and other food stores on ships. Ships carrying goods to English colonists in the Pacific spread house mice to remote islands. Habitat. House mice have had a commensal relationship with humans for at least 8,000 years. Thus, they are usually found in close association with human dwellings and other structures such as granaries, barns, and stores. They may live in stone walls, fencerows, cultivated fields, and other areas of dense cover close to buildings during warmer seasons and retreat to buildings during winter. They do not hibernate. House mice nest in cracks and crevices in stone walls, in woodpiles, behind rafters, or in other snug places near food, rarely moving more than 50 ft. (16 m) from these secure spots to feed. In dense grass,

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Top: The house mouse is of Asian origin, and recent genetic analysis supports the Indian subcontinent as its likely source. However, many have long thought of Central Asia as the starting place for this rodent, which has traveled around the world with humans. Bottom: The house mouse occurs throughout the United States, except for most of Alaska.

they will make their own runways or share those made by native mice. House mice are rarely encountered in undisturbed or natural habitats. Diet. House mice prefer cereal grains, but consume a variety of other plant material including fleshy roots, leaves, and stems. They also eat insects and sometimes meat. In houses, they will nibble on any type of human food as well as glue, paste, and soap. They are physiologically capable of extracting much of the water they need from their food and concentrate their urine, so they may live without free water if the food supply available to them allows. Life History. House mice have a very high reproductive potential and may, in mild climates, breed all year. Free-living populations outside of human habitations tend to have a seasonal breeding pattern and may only breed from early summer into fall. A female produces 15– 150 young in a year, depending on conditions. Individual mice will make their own nests even though they live in groups and share escape holes, latrines, and

House Mice in the Laboratory

D

omesticated house mice are common laboratory animals in medical and genetic research. Many inbred strains have been developed since Clarence Cook Little developed the first such population in 1909. Mutant strains have been since created by normal breeding, by insertion of foreign genes, and by gene knockout, a process that makes selected genes inoperable. Cloning mice has been possible since 1998. In 2002, sequencing the mouse genome, which has many human homologues that make it such a valuable model for research on human diseases, was finalized.

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feeding areas. The nests are constructed of finely shredded paper and other soft fibrous materials. After a gestation period of 19–21 days, a female gives birth to a litter of 5 or 6 (range 2–13) blind, hairless young whose ears and eyes are closed. Young mice are fully furred at 10 days of age, open their eyes at 14 days, and are weaned at 21 days. After weaning, they leave their mother’s territory. Females are sexually mature when 35 days old, males when 60 days old. A female may have 5–10 litters in The house mouse has relatively large rounded ears and prominent black a year. The average lifespan is eyes. Neither the dark back nor the upper tail is sharply demarcated from paler undersides. (Gertjan Hooijer/Shutterstock.) 12–18 months. Impacts. House mice have not contributed to the extinction of any species in the United States, nor do they compete with native mice. They do not carry the hantavirus that can be problematic with infestations of native mice in the western states. They also have not caused the serious health problems associated with Old World rats (see Mammals, Black Rat, and Norway Rat), although they may carry some of the same pathogens. However, they are major agricultural pests in some areas because they consume grains and other feedstuffs and contaminate food with their urine and droppings. In buildings, they gnaw and can destroy electric wiring (creating a fire hazard), insulation, woodwork, furniture, upholstery, and clothing. Management. House mice can be controlled with poisons, fumigants, traps, and repellants. To mouse-proof a structure, all openings greater than 0.25 in. (6 mm) must be blocked. All grain, pet food, and human food should be cleaned up and stored in rodent-proof containers. Outside, removing debris and cutting and thinning dense vegetation can discourage house mice. On those islands where mice have been eradicated, an anticoagulant poison was administered.

Selected References Ballenger, L. “Mus musculus.” Animal Diversity Web, University of Michigan Museum of Zoology, 1999. http://animaldiversity.ummz.umich.edu/site/accounts/information/Mus_musculus.html. Barwell, Ezra. “Mus musculus (mammal).” ICUN/SSC Invasive Species Group (ISSG), ISSG Global Invasive Species Database, 2006. http://www.issg.org/database/species/ecology.asp?fr=1&si=97. Davis, William B., and David J. Schmidly. “House Mouse.” Mammals of Texas—Online version. Texas Tech University, 1997. http://www.nsrl.ttu.edu/tmot1/mus_musc.htm. “House Mouse.” Wikipedia, 2009. http://en.wikipedia.org/wiki/Mus_musculus#Mice_as _an_invasive_species. Timm, R. M. “House Mouse.” Pests of Homes, Structures, People, and Pets. Pest Notes, Publication 7483, University of California, Division of Agriculture and Natural Resources, 2006. http:// www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7483.html.

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n Indian Mongoose Also known as: small Indian mongoose, small Asian mongoose Scientific name: Herpestes javanicus Family: Herpestidae Native Range. Southwest and South Asia, from Iran through India and Myanmar (Burma) to the Malay Peninsula and Java. Populations in the West Indies and Hawai’i derive from animals originating in eastern India that were brought first to Jamaica. Distribution in the United States. Hawai’i (Hawai’i, Maui, Moloka’i, and O’ahu); Puerto Rico; U.S. Virgin Islands (St. Croix and St. John). Description. Mongooses are small, weasel-like carnivores with slender bodies and short legs. The long tail, equal to about 40 percent of head-body length, is robust and muscular at the base and tapers gradually toward the tip. The narrow head has a pointed snout and short ears. The short, soft, brown fur has golden flecks and is paler on the undersides than on the back. Their eyes are amber. Adults have head-body lengths of 20–26 in. (500–650 mm) and weigh 0.6–2 lbs. (300–900 g). Males are larger than females and have wider heads and more robust bodies. Introduction History. The first successful introduction of Top: The Indian mongoose is native to southern Asia from Iran to mongooses to the Caribbean Southeast Asia. It was brought to Jamaica to control rats and from there region occurred in 1872, when transported to other Caribbean islands and to Hawai’i. Bottom: The four males and five females from Indian mongoose is well established on Puerto Rico and several of the Kolkatta (Calcutta) were released Hawaiian Islands. (Both maps adapted from Yamada, F., and K. in Jamaica. They were intenSugimura. “Negative Impact of an Invasive Small Indian Mongoose tionally brought to the islands Herpestes javanicus on Native Wildlife Species and Evaluation of a Control Project in Amami-Ohshima and Okinawa Islands, Japan.” to control rats that were desGlobal Environmental Research 8: 117–24, 2004. http://www.aires.or.jp/ troying the sugarcane crop. From Jamaica, mongooses were publication/ger/pdf/08-02-02.pdf.)

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A. The Indian mongoose is a weasel-like animal with a robust tail. (Bill Hubick Photography.) B. The head is narrow with a pointed snout and amber eyes. (Bill Hubick Photography.)

deliberately taken to other Caribbean islands including, between 1877 and 1879, Puerto Rico, St. Croix, and St. John for the same rat-control purpose. In 1883, Jamaican mongooses were imported by sugar growers on the Big Island of Hawai’i. Later they were taken to Mau’i, Moloka’i, and O’ahu. Habitat. In Puerto Rico and the U.S. Virgin Islands, mongooses are most abundant in drier habitats, but in Hawai’i, they inhabit rainforest. They may also be found near human settlements. Diet. Mongooses feed primarily on invertebrates, but will take small vertebrates and fruits. On O’ahu and Moloka’i, cockroaches are a major part of the diet. Studies in the West Indies and on the Hawaiian islands indicate that the main mammals consumed are introduced rats and house mice. Birds and reptiles usually comprise minor parts of the diet, although consumption of the eggs of ground-nesting birds and of sea turtles is well documented. They are strictly diurnal hunters. Life History. The time and length of the breeding season varies with latitude. In Hawai’i and the U.S. Virgin Islands, pregnant females have been trapped from February through August. Gestation lasts 49 days. Litter size ranges from one to five pups, but usually is two. At six weeks of age, young mongooses begin to hunt with their mothers, and they stay with her until they reach sexual maturity at 4–6 months. Females may produce 2–3 litters a year. Life expectancy is 4–5 years. Impacts. Although the IUCN lists the Indian mongoose as one of the world’s 100 worst invaders, its damage to the native fauna of Caribbean islands and Hawai’i may be exaggerated. In the early twentieth century in Puerto Rico, for example, mongooses were blamed for the decline of five ground-nesting birds (Key West Quail-dove [Geotrygon chrysia], Bridled Quail-dove [G. mystacea], Black Rail [Laterallus jamaicensis], Short-eared Owl [Asio flammeus], and Puerto Rican Nightjar [Caprimulgis moctitherus]). The nightjar was believed to have gone extinct, but was rediscovered in 1961 in areas with and without mongoose populations. With the exception of the Black Rail, populations of all these birds have rebounded, suggesting a balance may have developed between the native birds and exotic predator. By the 1980s, the Bridled Quail-dove had shifted to nesting in trees and was common on St. Croix.

286 n VERTEBRATES (MAMMALS) In Hawai’i also, the mongoose is blamed for the reduction or extirpation of several endemic birds, but documentation of predation is difficult and rare. Among the birds listed as threatened by mongooses are eight on the federal list of endangered species: the Hawaiian Goose or Ne¯ne¯ (Branta sandvicensis), the Hawaiian Crow or ‘Alala¯ (Corvus hawaiiaensis), the Hawaiian Duck or Koloa (Anas wyvilliana), the Hawaiian Coot or Alae ke’koke’o (Fulica alai), the Hawaiian Stilt or A’eo (Himantopus mexicanus knudseni), the Hawaiian Gallinule or Alae ‘ula (Gallinula chloropus sandvicensis), the Hawaiian Petrel or ‘Ua’u (Pterodroma sandwichensis), and the Newell Shearwater or ‘A’o (Puffinus auricularis newelli). Contrary to popular stories, mongooses are not responsible for black rats nesting in roofs and trees; this is the rats’ natural behavior. Mongooses, however, do seem to have shifted the relative abundance of introduced rats in Hawai’i in favor of black rats to the detriment of Norway rats and Polynesian rats (Rattus exulans), both ground-nesters. A similar pattern has been noted on St. Croix, where there are more black rats than Norway rats in mongoose habitat. In Puerto Rico, Norway rats exist only in areas free of mongooses, but black rats co-occur with mongooses. Mongooses were not introduced to St. Croix or Nevis until well after the disappearance of two native snakes, the Saint Croix racer (Alsophis sanctaecrucis) and orange-bellied racer (A. rufiventris), so blaming mongooses for the reptiles’ extinctions is erroneous. However, they are implicated in the loss of the Saint Croix ground lizard (Ameiva polops) and in reduced populations of lizards and amphibians elsewhere. Mongooses are known to prey upon the eggs and hatchlings of four sea turtle species on Caribbean islands: the hawksbill sea turtle (Eretmochelys imbricata), leatherback turtle (Dermochelys coriacea), green sea turtle (Chelonia mydas), and loggerhead sea turtles (Caretta caretta). Since mongooses do prey on reptiles and birds, they represent one more danger to already threatened species on islands and are considered a major deterrent to the recovery or reestablishment of island endemics. Management. Mongooses are often naturalized members of ecosystems into which they were introduced and may not need management. Trapping is the most common tool used in sensitive areas such as nesting grounds of seabirds and sea turtles. However, trapping is expensive and labor intensive, and has only temporary results, so it is not generally employed. The use of diphacinone, an anticoagulant, has had positive results in trials. Prevention of introduction into areas where mongooses do not already exist is the preferred course of action. In Hawai’i, state law forbids any person to introduce, keep, or breed mongooses without permits from the Hawai’i Department of Agriculture, which will not issue them for mongoose-free islands.

Selected References Hays, Warren S. T., and Sheila Conant. “Biology and Impacts of Pacific Island Invasive Species. 1. A Worldwide Review of Effects of the Small Indian Mongoose, Herpestes javanicus (Carnivora: Herpestidae).” Pacific Science 61 (1): 3–16, 2007. “Mongoose (Herpestes javanicus).” Hawai’i Invasive Species Partnership, 2008. http://www .hawaiiinvasivespecies.org/pests/mongoose.html. Roy, Sugoto. “Herpestes javanicus (Mammal).” IUCN/SSC Invasive Species Specialist Group, ISSG Global Invasive Species Database, 2006. http://www.issg.org/database/species/ecology.asp?si=86.

NORWAY RAT n 287

n Norway Rat Also known as: Brown rat, common rat, sewer rat, wharf rat Scientific name: Rattus norvegicus Family: Muridae Native Range. Northern China and Mongolia, perhaps originally living along stream banks, but for millennia living in close association with human settlement. (This rodent did not originate in Norway, as its name mistakenly implies. Indeed, it was unknown in Europe until the medieval period and did not make its way into Western Europe until the early 1700s.) Distribution in the United States. Found throughout the United States. Description. Norway rats have coarse brown or dark-gray fur dorsally with underparts a lighter shade of the general body color. The tail is hairless and scaly, and shorter than the headbody length. The ears are prominent but relatively short and bald. Adult head-body length averages about 10 in. (25 cm), total length about 15.5 in. (39 cm). Adult body weight ranges from 0.5 to 1.0 lb. (200–400 g); males are larger than females. The presence of these nocturnal animals is often indicated by their droppings, the effects of gnawing and rubbing, and sounds such as scratching and squeaking in the walls. Droppings occur in runways, feeding areas, and near sites of shelter; single pellets can reach 0.75 in. (2 cm) in length and 0.25 in. (0.6 cm) in diameter. Related or Similar Species. The smaller black rat (Rattus rattus), another invasive species (see Mammals, Black Rat), has a tail that is longer than its headbody length. Native woodrats (Neotoma spp.) have white undersides. The black rat is much Top: The Norway rat originated in northern China and Mongolia and not rarer in the United States than Norway, as its common and scientific names imply. Bottom: The Norway the Norway, having been largely rat arrived in the United States at the time of the American Revolution and replaced by it after the Norway largely replaced alien black rats. Today it is found in all 50 states and Puerto Rico. rat arrived in this country.

288 n VERTEBRATES (MAMMALS) Introduction History. The early history of the rat as a human commensal is still to be unraveled, but it appears to have spread along routes of human migration and trade out of northern China and Mongolia during the Middle Ages. Stowaways on ships, Norway rats were present in England by 1730 and soon were reported in other European countries, reaching Spain by 1800. The first rats showed up in North America prior to or during the American Revolution (1770s), according to some accounts, arriving in Norway rats have coarse brown or gray fur on the back; the underparts grain stores brought in with are lighter. The hairless scaly tail is shorter than head-body length. Hessian soldiers fighting with (S. Cooper Digital/Shutterstock.) the British against the American colonists. Rats then moved from port to port as accidental hitchhikers on ships. On land, their prodigious ability to reproduce, their adaptability to a wide range of habitat and food types, their propensity to live with humans, and their ability to climb, swim, jump, and dig allowed them to expand their range and invade farmstead, village, town, and city. When overcrowding occurs, they will undertake mass migrations to new areas. The rats on Rat Island, Alaska, finally eradicated in 2009, derived from the wreck of a Japanese ship in 1780. Habitat. The Norway rat occurs in close association with humans, occupying such manmade environments as cities, towns, farms, garbage dumps, and sewers. They may also be found in disturbed and human-modified habitats such as marshes, vacant lots, and open fields and may dig complex systems of burrows in the banks of streams and canals. They are excellent swimmers. Away from water, they are ground dwellers, and in buildings, they prefer cellars and lower floors, although they can climb. They may also burrow under foundations and sidewalks as well as roads and railroad tracks. Diet. True omnivores, Norway rats eat everything humans eat and more. Experimental studies show that, if available, they will select a well-balanced, nutritious diet of fresh foods including cereals, meat, fish, nuts, and fruits. Household garbage usually provides adequate moisture and limits their need for drinking water. They forage mainly at night, led by their excellent sense of smell. Cautious about new food, they avoid unfamiliar items at first and then test small amounts to see if it will make them sick. They can detect very low levels of contaminants, making poisoning a problematic strategy for rat control. Life History. Norway rats construct nests below ground and line them with leaves, twigs, shredded paper, or other fibrous materials. Each female gives birth to a litter of about eight pups after a gestation period lasting 22–24 days. Several females may use the same communal nest, and all females care for all of the young. The small, hairless pups do not open their eyes for 14–17 days and will not be weaned until 3–4 weeks old, at which time they leave the nest. Females come into estrous about 18 hours after giving birth and will mate.

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Good Rats

R

ats are often associated with filth and disease, but domestic descendents of the Norway rat have had a positive influence on humanity. They are commonly used in research and are familiar to undergraduates as the albino laboratory rat that runs through mazes and is subjected to a variety of behavioral experiments in psychology classes. Domestication has also produced the fancy or pet rat, a clean and intelligent companion animal that comes in a variety of colors and markings. Most American laboratory rats trace their origins to the Wistar Institute in Philadelphia, where in 1906 an albino strain was developed by Helen Dean King for use in biological research. Later strains include the Sprague-Dawley rat, a multipurpose research animal prized for its docility; the black-hooded Long Evans rat used in behavioral and obesity studies; Zucker rats, lean and obese forms of which are used in the understanding the genetics of obesity; and hairless rats that serve as models for research on immune-deficiency diseases and genetic kidney diseases. Domestic rats may go back to the eighteenth and nineteenth centuries, when rat-catchers were employed throughout Europe to trap rats. Many of the captives ended up as the bait in a bloodsport in which terriers competed (and people made wagers) to see how fast they could kill all the rats in a pit. Some naturally occurring albinos or oddly colored and marked rodents were apparently kept and the tamest bred and sold as pets. Rat fancy first became a formal hobby in England when the National Mouse Club accepted rats at an exhibition in 1901. In 1976 the National Fancy Rat Society was established in England, and in 1983 the American Fancy Rat and Mouse Association was founded in California.

Sources: “Fancy Rat.” Wikipedia. http://en.wikipedia.org/wiki/Fancy_rat. Hanson, Anne. “History of the Norway rat (Rattus norvegicus)” Rat behavior and biology. 2003, 2004. http://www.ratbehavior.org/history.htm. “Laboratory rat.” n.d. Wikipedia. http://en.wikipedia.org/wiki/Laboratory_rat.

Breeding occurs year round, although mating peaks in spring and fall in the temperate climates of the United States. An individual female may breed as many as seven times and produce some 60 offspring a year. Young males reach reproductive maturity at three months of age, females at four months. Normal lifespan for a wild rat is two years. Impacts. Worldwide, especially on islands, Norway rats have been implicated in the extinction or range reduction of native species through both competition and predation. On Rat Island in the western Aleutians of Alaska, for example, rat predation on eggs and chicks led to the extirpation of such burrow-nesting seabirds as Cassin’s Auklet (Ptychorampus aleuticus), Tufted Puffin (Fratercula cirrhata), and Storm Petrels (Oceanodroma spp.), and likely contributed to population losses among several other ground- and crevice-nesting shorebirds. In most of the United States, they are mainly an agricultural pest and urban menace. Rats consume crops and contaminate stored food with their feces and urine. They eat bird eggs and kill young poultry. They gnaw and dig their way into buildings, where they can cause structural damage to walls and floors, destroy insulation as they nest in and burrow in walls, and gnaw electrical wires to cause short circuits and fires. Their burrows may undermine roads, bridges, canals, and levees.

290 n VERTEBRATES (MAMMALS) The fleas and lice on rats carry infectious bacterial diseases to both human and livestock, including murine typhus and bubonic plague, although the latter has been more closely associated with black rats throughout history. Flies, mosquitoes, and ticks transmit tularemia from rats to humans; their ticks also carry spotted fever. Contact with the urine of rats in contaminated soil, water, or plants can transmit the bacterium Leptospira interrogans, the cause of infectious jaundice or leptospirosis, to livestock and humans. Food poisoning (salmonellosis) from contaminated feed is particularly dangerous to horses. Contaminated food may also harbor the nematodes that cause trichinosis. Bites can transmit rat bite fever. Norway rats are responsible for millions of dollars of damage to crops and buildings in the United States every year. Management. On islands, poisoning rats with anticoagulants has been successful in eradicating populations. Less slow-acting poisons are quickly learned and avoided by these highly intelligent rodents. Other effective control methods include rat-proofing buildings by blocking entry points, storing food in rat-proof containers, and removing potential shelter sites such as trash heaps, overgrown vegetation, and woodpiles.

Selected References Hanson, Anne. “History of the Norway Rat (Rattus norvegicus).” Rat Behavior and Biology, 2004. http:// www.ratbehavior.org/history.htm. ICUN/SSC Invasive Species Group (ISSG). “Rattus norvegicus (mammal).” ISSG Global Invasive Species Database, 2006. http://www.issg.org/database/species/ecology.asp?si=159. Myers, P., and D. Armitage. “Rattus norvegicus.” Animal Diversity Web, University of Michigan Museum of Zoology, 2004. http://animaldiversity.ummz.umich.edu/site/accounts/information/Rattus _norvegicus.html. “Norway Rat, Rattus norvegicus.” eNature.com, 2007. http://www.enature.com/fieldguides/detail.asp ?recnum=MA0095. “Norway Rats.” Internet Center for Wildlife Damage Management, Cornell University, Clemson University, University of Nebraska–Lincoln, and Utah State University, 2005. http://icwdm.org/ handbook/rodents/NorwayRats.asp.

n Nutria Also known as: Coypu, swamp beaver Scientific name: Myocastor coypus Family: Myocastoridae Native Range. Subtropical South America: Argentina, southern Brazil, Bolivia, Chile, Uruguay, and Paraguay. These large, semiaquatic rodents are found chiefly in the lowlands, but may range to elevations of 4,000 ft. (1,190 m) in the Andes. Distribution in the United States. Alabama, Arkansas, Colorado, Delaware, Florida, Georgia, Idaho, Louisiana, Maryland, Mississippi, New Mexico, North Carolina, Oklahoma, Oregon, Tennessee, Texas, Virginia, and Washington. Description. This is a fairly large, stocky rodent with a large, nearly triangular head and short neck. The eyes and ears are small and positioned high on the head. The nostrils and mouth can be sealed to prevent the intake of water when it dives or feeds underwater. The prominent front teeth range in color from yellow to dark orange. The tail, which comprises roughly one-third of total body length, is round and scaly with a sparse cover of bristles. Four toes on their hind feet are webbed, but the outermost, fifth toe is free. The much smaller, black forefeet have four

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unwebbed toes that provide dexterity in digging and manipulating food items. The 4–5 pairs of teats on the female are located high on the flank so that young may nurse while their mother is in the water or lying on her abdomen. The fur that made them so valuable in the past is actually a dense, velvety slategray undercoat concealed beneath long, coarse, but glossy yellowish-brown guard hairs. White hairs cover the chin. Head and body length ranges from 20 to 25 in.; tail length from 10–17 in. (25–43 cm). Nutria may weigh as much as 15–20 lbs. (6.8–9.0 kg); males are larger than females. Nutria droppings are cylindrical in shape and as much as 3 in. (7.6 cm) long. Fine, length-wise grooves distinguish them from the fecal pellets of other animals. Droppings will be seen floating on the water, along the shore, and at feeding sites. Nutria are nocturnal and most commonly seen at twilight, usually when they are swimming. A distinguishing Top: Nutria are native to the wetlands of South America, south of the factor, then, is the narrow tail Tropic of Capricorn. (Adapted from map at http://en.wikipedia.org/ snaking behind them or arched wiki/File:Nutria-SouthAmerica.gif. ) Bottom: Nutria being raised on fur farms escaped captivity and established populations in numerous states, out of the water. Related or Similar Species. where they damage native marsh communities and can become agriculNutria are similar to native bea- tural pests. (Adapted from Fuller, Pam. “Myocastor coypus.” USGS Noningidenous Aquatic Species Database, Gainesville, FL, 2005. http:// ver (Castor canadensis) and nas.er.usgs.gov/queries/factsheet.aspx?speciesID=1089.) muskrat (Ondatra zibethica), but intermediate between the two in size and appearance. The nutria’s head resembles that of a beaver, but its tail is more like that of a muskrat. Beavers have flat, paddle-shaped tails, whereas muskrat tails are slender and flattened from side to side. Nutria are twice as large as muskrats and about a third the size of beavers. The tracks of nutria can be confused with those of beavers, which have five webbed toes. Nutria slides, slick muddy trails into the water, are much narrower than those of beavers. Nutria make flattened, circular platforms of coarse emergent vegetation 3–6 ft. (1–2 m) in diameter, where they feed, loaf, and groom, and sometimes give birth. Multiple runways radiate out from these platforms, which could be mistaken for muskrat houses.

292 n VERTEBRATES (MAMMALS)

A. The nutria’s prominent teeth range in color from yellow to dark orange. (Sters/Shutterstock.) B. Nutria are large, stocky rodents. Their small eyes and ears are set high on their large heads. (Bodil 1955/Shutterstock.)

Introduction History. The first nutria were deliberately introduced into the United States from South America in 1899 in an effort to establish new ventures in fur farming. The first attempt was made in Elizabeth Lake, California, but the animals failed to reproduce. Between 1899 and 1940, nutria ranches were started in Washington, Oregon, Michigan, New Mexico, Louisiana, Ohio, and Utah. The boom years for production were in the 1930s, after which time the industry collapsed due to low fur prices during World War II, competition from beaver pelts, and poor reproduction. Some ranchers released their nutria, while others simply failed to round up any that escaped during storms and floods, or because of poor confinement structures. Since these animals had all been bred on ranches, the free-roaming animals now are considered feral. For a time, nutria were viewed as weed cutters to control noxious vegetation or as ways to increase the take of fur trappers. Both state and federal agencies, as well as individuals, introduced nutria into Alabama, Arkansas, Georgia, Kentucky, Maryland, Mississippi, Oklahoma, Louisiana, and Texas. California’s small feral population was eradicated in the 1970s. Nutria were eradicated or simply failed to survive in Idaho, Indiana, Kansas, Kentucky, Michigan, Minnesota, Missouri, Montana, Nebraska, Ohio, and Utah. Maryland received nutria in 1943 as part of a federal program to establish an ill-fated experimental fur station in Blackwater National Wildlife Refuge. The first feral animals were reported in 1952, after the fur station proved unprofitable. Early attempts to eradicate nutria failed, and the population exploded and expanded their range into Delaware. Only recently have they finally been eradicated from Blackwater NWR, but small populations remain in Maryland. Elsewhere in the Chesapeake Bay region, a small population in Virginia is believed to have moved in from North Carolina. In the early 1930s, nutria were introduced into Louisiana near New Orleans, where they were quickly trapped out. They were introduced again in 1938, this time for fur farming, and many escaped captivity during a 1940 hurricane. In the next 60 years, feral populations dispersed into West Texas (1941), Arkansas (early 1960s) and Mississippi, reaching Tennessee in 1996. In Oregon and Washington, nutria were first imported in the late 1930s for fur farming. By the 1950s, some 600 farms had been established in the two states. Storms and flooding damaged holding pens and allowed animals to escape. Viable feral populations continue to

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exist in the Pacific Northwest. In Washington State, after a series of warm winters, nutria seem to be expanding their distribution area. Small feral populations survive in Colorado, Florida, New Mexico, North Carolina, Oklahoma, and Texas. Habitat. Nutria remain close to permanent water and may be associated with fresh and brackish marshes, swamps, and the shores of rivers, bayous, lakes, and drainage canals. They shelter in burrows that they excavate themselves, but they will also occupy the burrows of other species. Their burrows may be simple tunnels or a complex network of passages and chambers up to 50 ft. (15 m) long. Diet. Nutria are herbivores and consume a wide variety of terrestrial and aquatic plants, including the bark of trees. In the United States, favored foods include cordgrasses (Spartina spp.), bulrushes (Scirpus spp), spikerushes (Eleocharis spp.), flatsedges (Cyperus spp.) pickerelweeds (Pontederia spp.), arrowheads (Sagittaria spp.), and cattails (Typha spp.). They also eat baldcypress (Taxodium distichum) seedlings, duckweeds, and waterhyacinth (Eichornia crassipes; see Volume 2, Aquatic Plants, Waterhyacinth), an invasive plant species. Often nutria will cut a plant off at the waterline and carry it to a feeding platform that they have constructed in shallow water. Nutria also dig beneath the marsh surface and feed on the root mat. Life History. Nutria construct nests of coarse plant material in dens within their burrows. They reproduce throughout the year, producing two or litters annually. The female will come into estrus every 24–26 days and stay in heat 1–4 days. Gestation is about 130 days. Typically, 4–6 precocial young are born, although the original number of embryos may have been much higher. Prenatal embryo losses are common, especially in cold weather and among poorly nourished females; miscarriage rates are high. Estrus begins soon after the female miscarries or gives birth. She will mate with several males each time she comes into estrus. Young are born with full coats of fur and open eyes. Within a day, they swim and feed on plants. They will be weaned in 5–8 weeks. Nutria are sexually mature in 4–6 months. Adults usually live in pairs, but large numbers may congregate in favorable habitat. Individuals occupy only a small area throughout their lives, rarely traveling more than 600 ft. (180 m) from their dens each day. Wild nutria rarely live more than three years. Young may be taken by coyotes, foxes, raccoons, alligators, and owls; humans are the only predators of adults. Impacts. The damage nutria do to native ecosystems is related to both their feeding and their burrowing. Animals feeding directly on the root mat of marsh plants produce what is known as an “eat out.” The mat binding the marsh substrate together is weakened and soil is washed away, pockmarking the marsh with holes. In Louisiana some “eat outs” are 500 ac. (202 ha) in size. Deep swimming channels come to fragment the marsh and, in coastal areas, allow the influx of salt water. The channels or “runs” create more edge habitat exposed to erosion by wind and water. Productive wetlands can be turned into barren mudflats or open water, destroying habitat for marshland invertebrates, fish, and birds. Nutria feeding on the rhizomes of sea oat on the barrier islands of Mississippi has exposed the sand dunes to erosion. Large burrows made by nutria weaken river banks, levees, dams, and the sides of drainage canals and can lead to cave-ins and erosion during heavy rains. In man-made environments, nutria may girdle orchard trees as well as ornamental trees and shrubs. In the 1950s, expanding populations in Louisiana became pests in rice and sugar cane fields. Nutria has been nominated by the IUCN as one of “100 of the World’s Worst” invasive species.

294 n VERTEBRATES (MAMMALS) Management. Trapping and shooting have been the most effective ways of controlling feral populations of nutria, and high fur prices once made these viable strategies. With the fall of prices, Louisiana established a nutria control program that included a bounty system to encourage the harvest of 400,000 nutria a year from coastal areas. Part of that program involves promoting nutria as a source of lowfat, high-protein meat. The legal status of nutria varies from state to state, and influences control methods. In Delaware, they are considered furbearers and regulated as such. In Maryland, they are listed as “unprotected” and can be controlled as wildlife species when they cause damage to ecological or economic resources. In Virginia, nutria are “nuisance” species; there is open season all year for trapping them. In Washington State, nutria are classified as “prohibited,” meaning they may not be released into the wild and may not be transported without a permit from the Washington Department of Fish and Wildlife.

Selected References Bertolino, S. “Myocastor coypus (Mammal).” IUCN/SSC Invasive Species Specialist Group, ISSG Global Invasive Species Database, 2005. http://www.invasivespecies.net/database/species/ecology.asp ?si=99&fr=1&sts=. “Exotic Aquatics of the Gulf Coast: Nutria (Myocastor coypus).” La Mer, Louisiana Sea Grant, n.d. http:// www.lamer.lsu.edu/invasivespecies/nutria/index.html. “Invasive Species in the Chesapeake Watershed.” Chesapeake Bay Program and Maryland Sea Grant, 2002. http://www.mdsg.umd.edu/issues/restoration/non-natives/workshop/nutria.html. Link, Russell. “Living with Wildlife: Nutria.” Washington Department of Fish and Wildlife, 2006. http://wdfw.wa.gov/wlm/living/nutria.pdf. “Worldwide Distribution, Spread of, and Efforts to Eradicate the Nutria (Myocastor coypus).” National Wetlands Research Center, U.S. Geological Survey, 2008. http://www.nwrc.usgs.gov/special/ nutria/namerica.htm.

n State-by-State Occurrences of Invasive Microorganisms, Fungi, and Animals

Includes only the species featured in the Encyclopedia. Alabama Microorganisms: West Nile virus Fungi: Chestnut blight fungus, chytrid frog fungus, Dutch elm disease Invertebrates Cnidarian: Australian spotted jellyfish Mollusks: Asian clam, zebra mussel Arachnids: Honeybee tracheal mite, varroa mite Insects: Argentine ant, Asian tiger mosquito, common bed bug, Formosan subterranean termite, Japanese beetle, multicolored Asian lady beetle, red imported fire ant Vertebrates Fish: Brown trout, rainbow trout Birds: Cattle Egret, Eurasian Collared-Dove, European Starling, House Finch, House Sparrow, Monk Parakeet, Rock Pigeon Mammals: Black rat, feral cat, feral pig, house mouse, Norway rat, nutria Alaska Microorganisms Fungi: Chytrid frog fungus Invertebrates Tunicates: Chain tunicate Insect: Common bed bug Vertebrates Fish: Rainbow trout Birds: Cattle Egret, European Starling, Rock Pigeon Mammals: Feral cat, house mouse, Norway rat Arizona Microorganisms: West Nile virus Fungi: Chytrid frog fungus Invertebrates Annelid worms: European earthworms Mollusks: Asian clam, Chinese mystery snail, New Zealand mud snail, quagga mussel Arachnids: Honeybee tracheal mite, varroa mite Insect: Africanized honey bee, Argentine ant, Common bed bug, Formosan subterranean termite, multicolored Asian lady beetle Vertebrates Fish: Bighead carp, brown trout, gizzard shad, mosquitofish, rainbow trout Amphibians: African clawed frog, American bullfrog Birds: Cattle Egret, European Starling, House Sparrow, Rock Pigeon Mammals: Feral burro, feral cat, feral horse, feral pig, house mouse, Norway rat

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296 n STATE-BY-STATE OCCURRENCES OF INVASIVE MICROORGANISMS, FUNGI, AND ANIMALS Arkansas Microorganisms: West Nile virus Fungi: Chytrid frog fungus, Dutch elm disease Invertebrates Annelid worms: European earthworms Mollusks: Asian clam, zebra mussel Arachnids: Honeybee tracheal mite, varroa mite Insects: Africanized honey bee, Argentine ant, Asian tiger mosquito, common bed bug, Formosan subterranean termite, Japanese beetle, multicolored Asian lady beetle, red imported fire ant Vertebrates Fish: Bighead carp, brown trout, grass carp, rainbow trout Birds: Cattle Egret, Eurasian Collared-Dove, European Starling, House Finch, House Sparrow, Rock Pigeon Mammals: Feral cat, feral pig, house mouse, Norway rat, nutria California Microorganisms: Lyme disease bacterium, West Nile virus Fungi: Chytrid frog fungus, sudden oak death, white pine blister rust Invertebrates Tunicates: Chain tunicate, colonial tunicate Annelid worms: European earthworms Mollusks: Asian clam, Chinese mystery snail, golden apple snail, New Zealand mud snail, quagga mussel, zebra mussel Crustaceans: Chinese mitten crab, green crab Arachnids: Honeybee tracheal mite, varroa mite Insects: Africanized honey bee, Argentine ant, Brown marmorated stink bug, common bed bug, Formosan subterranean termite, glassy-winged sharpshooter, multicolored Asian lady beetle, red imported fire ant Vertebrates Fish: Bighead carp, brown trout, mosquitofish, rainbow trout, spotted tilapia Amphibians: African clawed frog, American bullfrog Birds: Cattle Egret, Eurasian Collared-Dove, European Starling, House Sparrow, Rock Pigeon Mammals: Black rat, feral burro, feral cat, feral goat, feral horse, feral pig, house mouse, Norway rat Colorado Microorganisms: West Nile virus Fungi: Chytrid frog fungus, white pine blister rust Invertebrates Annelid worms: European earthworms Mollusks: Asian clam, Chinese mystery snail, New Zealand mud snail, quagga mussel, zebra mussel Arachnids: Honeybee tracheal mite, varroa mite Insects: Common bed bug, Japanese beetle, multicolored Asian lady beetle Vertebrates Fish: Alewife, bighead carp, brown trout, gizzard shad, mosquitofish, rainbow trout Amphibians: American bullfrog: Birds: Cattle Egret, Eurasian Collared-Dove, European Starling, House Sparrow, Rock Pigeon Mammals: Feral cat, feral horse, feral pig, house mouse, Norway rat, nutria

STATE-BY-STATE OCCURRENCES OF INVASIVE MICROORGANISMS, FUNGI, AND ANIMALS n 297 Connecticut Microorganisms: Lyme disease bacterium, West Nile virus Fungi: Bat white-nose syndrome, chestnut blight fungus, chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Bryozoan: Lacy crust bryozoan Tunicates: Chain tunicate, colonial tunicate Annelid worms: European earthworms Mollusks: Asian clam, Chinese mystery snail, common periwinkle, zebra mussel Crustaceans: Green crab, rusty crayfish Arachnids: Honeybee tracheal mite, varroa mite Insects: Common bed bug, gypsy moth, hemlock woolly adelgid, multicolored Asian lady beetle Vertebrates Fish: Brown trout, mosquitofish, rainbow trout Birds: Cattle Egret, European Starling, House Finch, House Sparrow, Monk Parakeet, Mute Swan, Rock Pigeon Mammals: Feral cat, house mouse, Norway rat Delaware Microorganisms: Lyme disease bacterium, West Nile virus Fungi: Bat white-nose syndrome, chestnut blight fungus, chytrid frog fungus, Dutch elm disease Invertebrates Tunicates: Chain tunicate Annelid worms: European earthworms Mollusks: Asian clam, common periwinkle Crustaceans: Green crab Arachnids: Honeybee tracheal mite, varroa mite Insects: Asian tiger mosquito, brown marmorated stink bug, common bed bug, gypsy moth, hemlock woolly adelgid, Japanese beetle, multicolored Asian lady beetle Vertebrates Fish: Brown trout, rainbow trout Birds: Cattle Egret, European Starling, House Finch, House Sparrow, Monk Parakeet, Mute Swan, Rock Pigeon Mammals: Feral cat, house mouse, Norway rat, nutria Florida Microorganisms: West Nile virus Fungi: Chytrid frog fungus, Dutch elm disease Invertebrates Cnidarian: Australian spotted jellyfish Mollusks: Asian clam, Asian green mussel, golden apple snail Arachnids: Honeybee tracheal mite, varroa mite Insects: Africanized honey bee, Argentine ant, Asian tiger mosquito, common bed bug, Formosan subterranean termite, multicolored Asian lady beetle, red imported fire ant Vertebrates Fish: Asian swamp eel, bighead carp, brown trout, lionfish, mosquitofish, rainbow trout, spotted tilapia, walking catfish Amphibians: Coqui (noninvasive), Cuban treefrog Reptiles: Brown anole, Burmese python, green iguana, Nile monitor Birds: Cattle Egret, Common Myna, Eurasian Collared-Dove, European Starling, House Finch, House Sparrow, Monk Parakeet, Rock Pigeon Mammals: Black rat, feral cat, feral pig, house mouse, Norway rat, nutria

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298 n STATE-BY-STATE OCCURRENCES OF INVASIVE MICROORGANISMS, FUNGI, AND ANIMALS Georgia Microorganisms: West Nile virus Fungi: Chestnut blight fungus, chytrid frog fungus, Dutch elm disease Invertebrates Annelid worms: European earthworms Mollusks: Asian clam, Asian green mussel Arachnids: Honeybee tracheal mite, varroa mite Insects: Argentine ant, Asian tiger mosquito, common bed bug, Formosan subterranean termite, hemlock woolly adelgid, Japanese beetle, multicolored Asian lady beetle, red imported fire ant Vertebrates Fish: Alewife, Asian swamp eel, brown trout, lionfish, rainbow trout Reptiles: Brown anole Birds: Cattle Egret, Eurasian Collared-Dove, European Starling, House Finch, House Sparrow, Rock Pigeon Mammals: Black rat, feral cat, feral horse, feral pig, house mouse, Norway rat, nutria Hawai’i Microorganisms: Avian malaria Fungi: Chytrid frog fungus Invertebrates Cnidarian: Australian spotted jellyfish Mollusks: Asian clam, giant African snail, golden apple snail, zebra mussel Insects: Argentine ant, Asian tiger mosquito, common bed bug, Formosan subterranean termite Vertebrates Fish: Asian swamp eel, bighead carp, brown trout, mosquitofish, rainbow trout Amphibians: American bullfrog, coqui Reptiles: Green iguana Birds: Cattle Egret, Common Myna, European Starling, House Finch, House Sparrow, Japanese White-eye, Rock Pigeon Mammals: Black rat, feral cat, feral goat, feral pig, house mouse, Indian mongoose, Norway rat Idaho Microorganisms: West Nile virus Fungi: Chytrid frog fungus, white pine blister rust Invertebrates Annelid worms: European earthworms Mollusks: Asian clam, New Zealand mud snail Arachnids: Honeybee tracheal mite, varroa mite Insects: Common bed bug, multicolored Asian lady beetle Vertebrates Fish: Brown trout, mosquitofish, rainbow trout Birds: Cattle Egret, European Starling, House Sparrow, Rock Pigeon Mammals: Feral cat, house mouse, Norway rat, nutria Illinois Microorganisms: Lyme disease bacterium, West Nile virus Fungi: Chestnut blight fungus, chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Annelid worms: European earthworms Mollusks: Asian clam, Chinese mystery snail, quagga mussel, zebra mussel

STATE-BY-STATE OCCURRENCES OF INVASIVE MICROORGANISMS, FUNGI, AND ANIMALS n 299 Arachnids: Honeybee tracheal mite, varroa mite Insects: Argentine ant, Asian longhorned beetle, Asian tiger mosquito, common bed bug, emerald ash borer, gypsy moth, Japanese beetle, multicolored Asian lady beetle Vertebrates Fish: Alewife, brown trout, gizzard shad, mosquitofish, rainbow trout, round goby, sea lamprey, silver carp Birds: Cattle Egret, Eurasian Collared-Dove, European Starling, House Finch, House Sparrow, Monk Parakeet, Rock Pigeon Mammals: Feral cat, feral pig, house mouse, Norway rat Indiana Microorganisms: Lyme disease bacterium, West Nile virus Fungi: Chestnut blight fungus, chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Annelid worms: European earthworms Mollusks: Asian clam, Chinese mystery snail, zebra mussel Arachnids: Honeybee tracheal mite, varroa mite Insects: Asian tiger mosquito, common bed bug, emerald ash borer, gypsy moth, Japanese beetle, multicolored Asian lady beetle Vertebrates Fish: Alewife, bighead carp, brown trout, gizzard shad, mosquitofish, rainbow trout Birds: Cattle Egret, European Starling, House Finch, House Sparrow, Rock Pigeon Mammals: Feral cat, feral pig, house mouse, Norway rat Iowa Microorganisms: Lyme disease bacterium, West Nile virus Fungi: Chestnut blight fungus, chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Annelid worms: European earthworms Mollusks: Asian clam, Chinese mystery snail, quagga mussel, zebra mussel Crustaceans: Rusty crayfish Arachnids: Honeybee tracheal mite, varroa mite Insects: Common bed bug, Japanese beetle, multicolored Asian lady beetle Vertebrates Fish: Bighead carp, brown trout, mosquitofish, rainbow trout Amphibians: American bullfrog (in DeSoto NWR) Birds: Cattle Egret, Eurasian Collared-Dove, European Starling, House Finch, House Sparrow, Rock Pigeon Mammals: Feral cat, feral pig, house mouse, Norway rat Kansas Microorganisms: West Nile virus Fungi: Chytrid frog fungus, Dutch elm disease Invertebrates Mollusks: Asian clam, zebra mussel Arachnids: Honeybee tracheal mite, varroa mite Insects: Asian tiger mosquito, common bed bug, Japanese beetle, multicolored Asian lady beetle Vertebrates Fish: Bighead carp, brown trout, gizzard shad, mosquitofish, rainbow trout Birds: Cattle Egret, Eurasian Collared-Dove, European Starling, House Finch, House Sparrow, Rock Pigeon Mammals: Feral cat, feral pig, house mouse, Norway rat

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300 n STATE-BY-STATE OCCURRENCES OF INVASIVE MICROORGANISMS, FUNGI, AND ANIMALS Kentucky Microorganisms: West Nile virus Fungi: Chestnut blight fungus, chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Annelid worms: European earthworms Mollusks: Asian clam, quagga mussel, zebra mussel Arachnids: Honeybee tracheal mite, varroa mite Insects: Africanized honey bee, Asian tiger mosquito, common bed bug, emerald ash borer, hemlock woolly adelgid, Japanese beetle, multicolored Asian lady beetle Vertebrates Fish: Alewife, bighead carp, brown trout, gizzard shad, grass carp, mosquitofish, rainbow trout Birds: Cattle Egret, Eurasian Collared-Dove, European Starling, House Finch, House Sparrow, Rock Pigeon Mammals: Feral cat, feral pig, house mouse, Norway rat Louisiana Microorganisms: West Nile virus Fungi: Chytrid frog fungus, Dutch elm disease Invertebrates Cnidarian: Australian spotted jellyfish Annelid worms: European earthworms Mollusks: Zebra mussel Arachnids: Honeybee tracheal mite, varroa mite Insects: Africanized honey bee, Argentine ant, Asian tiger mosquito, common bed bug, Formosan subterranean termite, multicolored Asian lady beetle, red imported fire ant Vertebrates Fish: Bighead carp, grass carp, rainbow trout, silver carp Birds: Cattle Egret, Eurasian Collared-Dove, European Starling, House Finch, House Sparrow, Monk Parakeet, Rock Pigeon Mammals: Black rat, feral cat, feral pig, house mouse, Norway rat, nutria Maine Microorganisms: West Nile virus Fungi: Chestnut blight fungus, chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Bryozoan: Lacy crust bryozoan Tunicates: Chain tunicate, colonial tunicate Annelid worms: European earthworms Mollusks: Asian clam, Chinese mystery snail, common periwinkle Crustaceans: Green crab, rusty crayfish Arachnids: Honeybee tracheal mite, varroa mite Insects: Common bed bug, gypsy moth, hemlock woolly adelgid, multicolored Asian lady beetle Vertebrates Fish: Alewife, brown trout, rainbow trout Birds: Cattle Egret, European Starling, House Finch, House Sparrow, Mute Swan, Rock Pigeon Mammals: Feral cat, house mouse, Norway rat Maryland Microorganisms: Lyme disease bacterium, West Nile virus

STATE-BY-STATE OCCURRENCES OF INVASIVE MICROORGANISMS, FUNGI, AND ANIMALS n 301 Fungi: Bat white-nose syndrome, chestnut blight fungus, chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Tunicates: Chain tunicate Annelid worms: European earthworms Mollusks: Asian clam Crustaceans: Green crab, rusty crayfish Arachnids: Honeybee tracheal mite, varroa mite Insects: Argentine ant, Asian tiger mosquito, brown marmorated stink bug, common bed bug, emerald ash borer, gypsy moth, hemlock woolly adelgid, Japanese beetle, multicolored Asian lady beetle Vertebrates Fish: Alewife, brown trout, mosquitofish, northern snakehead, rainbow trout Birds: Cattle Egret, European Starling, House Finch, House Sparrow, Mute Swan, Rock Pigeon Mammals: Feral cat, house mouse, Norway rat, nutria Massachusetts Microorganisms: Lyme disease bacterium, West Nile virus Fungi: Bat white-nose syndrome, chestnut blight fungus, chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Bryozoan: Lacy crust bryozoan Tunicates: Chain tunicate, colonial tunicate Annelid worms: European earthworms Mollusks: Asian clam, Chinese mystery snail, common periwinkle, zebra mussel Crustaceans: Green crab, rusty crayfish Arachnids: Honeybee tracheal mite, varroa mite Insects: Asian longhorned beetle, common bed bug, gypsy moth, hemlock woolly adelgid, Japanese beetle, multicolored Asian lady beetle Vertebrates Fish: Alewife, brown trout, mosquitofish, rainbow trout Amphibians: American bullfrog (on Nantucket, Martha’s Vineyard, and Cape Cod) Birds: Cattle Egret, European Starling, House Finch, House Sparrow, Mute Swan, Rock Pigeon Mammals: Feral cat, house mouse, Norway rat Michigan Microorganisms: Lyme disease bacterium, West Nile virus Fungi: Chestnut blight fungus, chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Annelid worms: European earthworms Mollusks: Asian clam, Chinese mystery snail, New Zealand mud snail, quagga mussel, zebra mussel Crustaceans: Rusty crayfish, spiny water flea Arachnids: Honeybee tracheal mite, varroa mite Insects: Common bed bug, emerald ash borer, gypsy moth, Japanese beetle, multicolored Asian lady beetle Vertebrates Fish: Alewife, brown trout, gizzard shad, mosquitofish, rainbow trout, round goby, sea lamprey Birds: Cattle Egret, European Starling, House Finch, House Sparrow, Mute Swan, Rock Pigeon Mammals: Feral cat, house mouse, Norway rat

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302 n STATE-BY-STATE OCCURRENCES OF INVASIVE MICROORGANISMS, FUNGI, AND ANIMALS Minnesota Microorganisms: Lyme disease bacterium, West Nile virus Fungi: Chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Annelid worms: European earthworms Mollusks: Asian clam, Chinese mystery snail, New Zealand mud snail, quagga mussel, zebra mussel Crustaceans: Rusty crayfish, spiny water flea Arachnids: Honeybee tracheal mite, varroa mite Insects: Asian tiger mosquito, common bed bug, emerald ash borer, Japanese beetle, multicolored Asian lady beetle Vertebrates Fish: Alewife, brown trout, mosquitofish, rainbow trout, round goby, sea lamprey Birds: Cattle Egret, European Starling, House Finch, House Sparrow, Rock Pigeon Mammals: Feral cat, house mouse, Norway rat Mississippi Microorganisms: West Nile virus Fungi: Chestnut blight fungus, chytrid frog fungus, Dutch elm disease Invertebrates Cnidarian: Australian spotted jellyfish Annelid worms: European earthworms Mollusks: Asian clam, zebra mussel Arachnids: Honeybee tracheal mite, varroa mite Insects: Africanized honey bee, Argentine ant, Asian tiger mosquito, common bed bug, Formosan subterranean termite, Japanese beetle, multicolored Asian lady beetle, red imported fire ant Vertebrates Fish: Bighead carp, rainbow trout Birds: Cattle Egret, Eurasian Collared-Dove, European Starling, House Finch, House Sparrow, Rock Pigeon Mammals: Black rat, feral cat, feral pig, house mouse, Norway rat, nutria Missouri Microorganisms: West Nile virus Fungi: Bat white-nose syndrome, chestnut blight fungus, chytrid frog fungus, Dutch elm disease Invertebrates Annelid worms: European earthworms Mollusks: Asian clam, Chinese mystery snail, quagga mussel, zebra mussel Crustaceans: Rusty crayfish Arachnids: Honeybee tracheal mite, varroa mite Insects: Argentine ant, Asian tiger mosquito, common bed bug, emerald ash borer, Japanese beetle, multicolored Asian lady beetle Vertebrates Fish: Brown trout, grass carp, mosquitofish, rainbow trout Birds: Cattle Egret, Eurasian Collared-Dove, European Starling, House Finch, House Sparrow, Rock Pigeon Mammals: Feral cat, feral pig, house mouse, Norway rat Montana Microorganisms: West Nile virus Fungi: Chytrid frog fungus, Dutch elm disease, white pine blister rust

STATE-BY-STATE OCCURRENCES OF INVASIVE MICROORGANISMS, FUNGI, AND ANIMALS n 303 Invertebrates Annelid worms: European earthworms Mollusks: New Zealand mud snail Arachnids: Honeybee tracheal mite, varroa mite Insects: Common bed bug, multicolored Asian lady beetle Vertebrates Fish: Brown trout, mosquitofish, rainbow trout Birds: Cattle Egret, Eurasian Collared-Dove, European Starling, House Sparrow, Rock Pigeon Mammals: Feral cat, feral horse, house mouse, Norway rat Nebraska Microorganisms: West Nile virus Fungi: Chytrid frog fungus, Dutch elm disease Invertebrates Mollusks: Asian clam, Chinese mystery snail, zebra mussel Arachnids: Honeybee tracheal mite, varroa mite Insects: Asian tiger mosquito, common bed bug, Japanese beetle, multicolored Asian lady beetle Vertebrates Fish: Alewife, bighead carp, brown trout, gizzard shad, mosquitofish, rainbow trout Birds: Cattle Egret, Eurasian Collared-Dove, European Starling, House Finch, House Sparrow, Rock Pigeon Mammals: Feral cat, feral pig, house mouse, Norway rat Nevada Microorganisms: West Nile virus Fungi: chytrid frog fungus, white pine blister rust Invertebrates Annelid worms: European earthworms Mollusks: Asian clam, New Zealand mud snail, quagga mussel Arachnids: Honeybee tracheal mite, varroa mite Insects: Africanized honey bee, Argentine ant, common bed bug, multicolored Asian lady beetle Vertebrates Fish: Brown trout, mosquitofish, rainbow trout, spotted tilapia Amphibians: American bullfrog Birds: Cattle Egret, European Starling, House Sparrow, Rock Pigeon Mammals: Feral burro, feral cat, feral horse, feral pig, house mouse, Norway rat New Hampshire Microorganisms: Lyme disease bacterium, West Nile virus Fungi: Bat white-nose syndrome, chestnut blight fungus, chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Bryozoan: Lacy crust bryozoan Tunicates: Chain tunicate, colonial tunicate Annelid worms: European earthworms Mollusks: Chinese mystery snail Crustaceans: Green crab, rusty crayfish Arachnids: Honeybee tracheal mite, varroa mite Insects: Common bed bug, gypsy moth, hemlock woolly adelgid, Japanese beetle

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304 n STATE-BY-STATE OCCURRENCES OF INVASIVE MICROORGANISMS, FUNGI, AND ANIMALS Vertebrates Fish: Alewife, brown trout, rainbow trout Birds: Cattle Egret, European Starling, House Finch, House Sparrow, Rock Pigeon Mammals: Feral cat, feral pig, house mouse, Norway rat New Jersey Microorganisms: Lyme disease bacterium, West Nile virus Fungi: Bat white-nose syndrome, chestnut blight fungus, chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Tunicates: Chain tunicate, colonial tunicate Annelid worms: European earthworms Mollusks: Asian clam, Chinese mystery snail, common periwinkle Crustaceans: Green crab, rusty crayfish Arachnids: Honeybee tracheal mite, varroa mite Insects: Asian longhorned beetle, Asian tiger mosquito, brown marmorated stink bug, common bed bug, gypsy moth, hemlock woolly adelgid, Japanese beetle, multicolored Asian lady beetle Vertebrates Fish: Asian swamp eel, brown trout, mosquitofish, rainbow trout Amphibians: American bullfrog (Cape May NWR) Birds: Cattle Egret, European Starling, House Finch, House Sparrow, Monk Parakeet, Mute Swan, Rock Pigeon Mammals: Feral cat, house mouse, Norway rat New Mexico Microorganisms: West Nile virus Fungi: Chytrid frog fungus, white pine blister rust Invertebrates Annelid worms: European earthworms Mollusks: Asian clam Arachnids: Honeybee tracheal mite, varroa mite Insects: Africanized honey bee, common bed bug, Formosan subterranean termite, multicolored Asian lady beetle, red imported fire ant Vertebrates Fish: Brown trout, rainbow trout Birds: Cattle Egret, Eurasian Collared-Dove, European Starling, House Sparrow, Rock Pigeon Mammals: Feral cat, feral horse, house mouse, Norway rat, nutria New York Microorganisms: Lyme disease bacterium, West Nile virus Fungi: Bat white-nose syndrome, chestnut blight fungus, chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Tunicates: Chain tunicate, colonial tunicate Annelid worms: European earthworms Mollusks: Asian clam, Chinese mystery snail, common periwinkle, quagga mussel, zebra mussel Crustaceans: Green crab, rusty crayfish, spiny water flea Arachnids: Honeybee tracheal mite, varroa mite Insects: Asian longhorned beetle, brown marmorated stink bug, common bed bug, emerald ash borer, gypsy moth, hemlock woolly adelgid, Japanese beetle, multicolored Asian lady beetle

STATE-BY-STATE OCCURRENCES OF INVASIVE MICROORGANISMS, FUNGI, AND ANIMALS n 305 Vertebrates Fish: Alewife, brown trout, mosquitofish, rainbow trout, round goby Birds: Cattle Egret, European Starling, House Finch, House Sparrow, Monk Parakeet, Mute Swan, Rock Pigeon Mammals: Feral cat, house mouse, Norway rat North Carolina Microorganisms: West Nile virus Fungi: Chestnut blight fungus, chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Annelid worms: European earthworms Mollusks: Asian clam Arachnids: Honeybee tracheal mite, varroa mite Insects: Argentine ant, Asian tiger mosquito, common bed bug, Formosan subterranean termite, gypsy moth, hemlock woolly adelgid, Japanese beetle, multicolored Asian lady beetle, red imported fire ant Vertebrates Fish: Alewife, brown trout, lionfish, rainbow trout Birds: Cattle Egret, Eurasian Collared-Dove, European Starling, House Finch, House Sparrow, Mute Swan, Rock Pigeon Mammals: Feral cat, feral horse, feral pig, house mouse, Norway rat, nutria North Dakota Microorganisms: West Nile virus Fungi: Chytrid frog fungus, Dutch elm disease Invertebrates Annelid worms: European earthworms Arachnids: Honeybee tracheal mite, varroa mite Insects: Common bed bug, multicolored Asian lady beetle Vertebrates Fish: Brown trout, rainbow trout Birds: Cattle Egret, European Starling, House Sparrow, Rock Pigeon Mammals: Black rat, feral cat, feral horse, house mouse, Norway rat Ohio Microorganisms: West Nile virus Fungi: Chestnut blight fungus, chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Annelid worms: European earthworms Mollusks: Asian clam, Chinese mystery snail, quagga mussel, zebra mussel Crustaceans: Spiny water flea Arachnids: Honeybee tracheal mite, varroa mite Insects: Asian tiger mosquito, common bed bug, emerald ash borer, gypsy moth, Japanese beetle, multicolored Asian lady beetle Vertebrates Fish: Alewife, brown trout, mosquitofish, rainbow trout, round goby, sea lamprey Birds: Cattle Egret, European Starling, House Sparrow, Rock Pigeon Mammals: Feral cat, feral pig, house mouse, Norway rat Oklahoma Microorganisms: West Nile virus Fungi: Chytrid frog fungus, Dutch elm disease

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306 n STATE-BY-STATE OCCURRENCES OF INVASIVE MICROORGANISMS, FUNGI, AND ANIMALS Invertebrates Crustaceans: Zebra mussel Arachnids: Honeybee tracheal mite, varroa mite Insect: Africanized honey bee, Argentine ant, Asian tiger mosquito, multicolored Asian lady beetle, red imported fire ant Vertebrates Fish: Bighead carp, brown trout, rainbow trout Birds: Cattle Egret, Eurasian Collared-Dove, European Starling, House Finch, House Sparrow, Rock Pigeon Mammals: Feral cat, feral pig, house mouse, Norway rat, nutria Oregon Microorganisms: West Nile virus Fungi: Chytrid frog fungus, sudden oak death, white pine blister rust Invertebrates Tunicates: Chain tunicate Annelid worms: European earthworms Mollusks: Asian clam, Chinese mystery snail, New Zealand mud snail Crustaceans: Green crab Arachnids: Honeybee tracheal mite, varroa mite Insects: Argentine ant, brown marmorated stink bug, common bed bug, multicolored Asian lady beetle Vertebrates Fish: Brown trout, mosquitofish, rainbow trout Amphibians: American bullfrog Birds: Cattle Egret, European Starling, House Sparrow, Monk Parakeet, Rock Pigeon Mammals: Black rat, feral burro, feral cat, feral horse, feral pig, house mouse, Norway rat, nutria Pennsylvania Microorganisms: Lyme disease bacterium, West Nile virus Fungi: Bat white-nose syndrome, chestnut blight fungus, chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Annelid worms: European earthworms Mollusks: Asian clam, Chinese mystery snail, quagga mussel, zebra mussel Crustaceans: Rusty crayfish, spiny water flea Arachnids: Honeybee tracheal mite, varroa mite Insects: Asian tiger mosquito, brown marmorated stink bug, common bed bug, Japanese beetle, multicolored Asian lady beetle Vertebrates Fish: Alewife, brown trout, gizzard shad, mosquitofish, northern snakehead, rainbow trout Birds: Cattle Egret, European Starling, House Finch, House Sparrow, Rock Pigeon Mammals: Feral cat, house mouse, Norway rat Rhode Island Microorganisms: Lyme disease bacterium, West Nile virus Fungi: Chestnut blight fungus, chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Bryozoan: Lacy crust bryozoan Tunicates: Chain tunicate, colonial tunicate Annelid worms: European earthworms Mollusks: Chinese mystery snail, common periwinkle Crustaceans: Green crab

STATE-BY-STATE OCCURRENCES OF INVASIVE MICROORGANISMS, FUNGI, AND ANIMALS n 307 Arachnids: Honeybee tracheal mite, varroa mite Insects: Common bed bug, gypsy moth, hemlock woolly adelgid, Japanese beetle, multicolored Asian lady beetle. Vertebrates Fish: Brown trout, rainbow trout Birds: Cattle Egret, European Starling, House Finch, House Sparrow, Monk Parakeet, Mute Swan, Rock Pigeon Mammals: Feral cat, house mouse, Norway rat South Carolina Microorganisms: West Nile virus Fungi: Chestnut blight fungus, chytrid frog fungus, Dutch elm disease Invertebrates Annelid worms: European earthworms Mollusks: Asian clam, Asian green mussel Arachnids: Honeybee tracheal mite, varroa mite Insects: Argentine ant, Asian tiger mosquito, common bed bug, Formosan subterranean termite, hemlock woolly adelgid, Japanese beetle, multicolored Asian lady beetle, red imported fire ant Vertebrates Fish: Alewife, brown trout, lionfish, rainbow trout Birds: Cattle Egret, Eurasian Collared-Dove, European Starling, House Finch, House Sparrow, Mute Swan, Rock Pigeon Mammals: Black rat, feral cat, feral pig, house mouse, Norway rat South Dakota Microorganisms: West Nile virus Fungi: Chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Mollusks: Zebra mussel Arachnids: Honeybee tracheal mite, varroa mite Insects: Common bed bug, multicolored Asian lady beetle Vertebrates Fish: Bighead carp, brown trout, rainbow trout Birds: Cattle Egret, European Starling, House Sparrow, Rock Pigeon Mammals: Feral burro, feral cat, house mouse, Norway rat Tennessee Microorganisms: West Nile virus Fungi: Bat white-nose syndrome, chestnut blight fungus, chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Annelid worms: European earthworms Mollusks: Asian clam, zebra mussel Arachnids: Honeybee tracheal mite, varroa mite Insects: Argentine ant, Asian tiger mosquito, brown marmorated stink bug, common bed bug, Formosan subterranean termite, hemlock woolly adelgid, Japanese beetle, multicolored Asian lady beetle, red imported fire ant Vertebrates Fish: Alewife, bighead carp, brown trout, grass carp, mosquitofish, rainbow trout Birds: Cattle Egret, Eurasian Collared-Dove, European Starling, House Finch, House Sparrow, Rock Pigeon Mammals: Feral cat, feral pig, house mouse, Norway rat, nutria

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308 n STATE-BY-STATE OCCURRENCES OF INVASIVE MICROORGANISMS, FUNGI, AND ANIMALS Texas Microorganisms: West Nile virus Fungi: Chestnut blight fungus, chytrid frog fungus, Dutch elm disease Invertebrates Mollusks: Asian clam, Chinese mystery snail, golden apple snail, zebra mussel Arachnids: Honeybee tracheal mite, varroa mite Insects: Africanized honey bee, Argentine ant, Asian tiger mosquito, common bed bug, Formosan subterranean termite, multicolored Asian lady beetle, red imported fire ant Vertebrates Fish: Bighead carp, brown trout, grass carp, mosquitofish, rainbow trout Reptiles: Green iguana Birds: Cattle Egret, Eurasian Collared-Dove, European Starling, House Sparrow, Monk Parakeet, Rock Pigeon Mammals: Black rat, feral cat, feral pig, house mouse, Norway rat, nutria Utah Microorganisms: West Nile virus Fungi: Chytrid frog fungus Invertebrates Annelid worms: European earthworms Mollusks: Asian clam, New Zealand mud snail, zebra mussel Arachnids: Honeybee tracheal mite, varroa mite Insects: Africanized honey bee, common bed bug, multicolored Asian lady beetle Vertebrates Fish: Brown trout, gizzard shad, mosquitofish, rainbow trout Amphibians: American bullfrog Birds: Cattle Egret, European Starling, House Sparrow, Rock Pigeon Mammals: Feral burro, feral cat, feral horse, house mouse, Norway rat Vermont Microorganisms: Lyme disease bacterium, West Nile virus Fungi: Bat white-nose syndrome, chestnut blight fungus, chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Annelid worms: European earthworms Mollusks: Asian clam, Chinese mystery snail, zebra mussel Arachnids: Honeybee tracheal mite, varroa mite Insects: Common bed bug, gypsy moth, hemlock woolly adelgid, Japanese beetle, multicolored Asian lady beetle Vertebrates Fish: Alewife, brown trout, rainbow trout Birds: Cattle Egret, European Starling, House Finch, House Sparrow, Rock Pigeon Mammals: Feral cat, house mouse, Norway rat Virginia Microorganisms: Lyme disease bacterium, West Nile virus Fungi: Bat white-nose syndrome, chestnut blight fungus, chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Tunicates: Chain tunicate Annelid worms: European earthworms Mollusks: Asian clam, veined rapa whelk, zebra mussel Crustaceans: Green crab

STATE-BY-STATE OCCURRENCES OF INVASIVE MICROORGANISMS, FUNGI, AND ANIMALS n 309 Arachnids: Honeybee tracheal mite, varroa mite Insects: Asian tiger mosquito, brown marmorated stink bug, common bed bug, emerald ash borer, Formosan subterranean termite, gypsy moth, hemlock woolly adelgid, Japanese beetle, multicolored Asian lady beetle, red imported fire ant Vertebrates Fish: Alewife, bighead carp, brown trout, mosquitofish, northern snakehead, rainbow trout Birds: Cattle Egret, European Starling, House Finch, House Sparrow, Monk Parakeet, Mute Swan, Rock Pigeon Mammals: Black rat, feral cat, feral horse, feral pig, house mouse, Norway rat, nutria Washington Microorganisms: West Nile virus Fungi: Chytrid frog fungus, white pine blister rust Invertebrates Tunicates: Chain tunicate, colonial tunicate Annelid worms: European earthworms Mollusks: Asian clam, Chinese mystery snail, New Zealand mud snail Crustaceans: Green crab Arachnids: Honeybee tracheal mite, varroa mite Insects: Common bed bug, multicolored Asian lady beetle Vertebrates Fish: Brown trout, rainbow trout Amphibians: American bullfrog Birds: Cattle Egret, European Starling, House Sparrow, Rock Pigeon Mammals: Black rat, feral cat, house mouse, Norway rat, nutria West Virginia Microorganisms: West Nile virus Fungi: Bat white-nose syndrome, chestnut blight fungus, chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Annelid worms: European earthworms Mollusks: Asian clam, zebra mussel Arachnids: Honeybee tracheal mite, varroa mite Insects: Asian tiger mosquito, brown marmorated stink bug, common bed bug, emerald ash borer, gypsy moth, hemlock woolly adelgid, Japanese beetle, multicolored Asian lady beetle Vertebrates Fish: Alewife, bighead carp, brown trout, mosquitofish, rainbow trout Birds: Cattle Egret, European Starling, House Finch, House Sparrow, Rock Pigeon Mammals: Feral cat, feral pig, house mouse, Norway rat Wisconsin Microorganisms: Lyme disease bacterium, West Nile virus Fungi: Chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Annelid worms: European earthworms Mollusks: Asian clam, Chinese mystery snail, New Zealand mud snail, zebra mussel Crustaceans: Rusty crayfish, spiny water flea Arachnids: Honeybee tracheal mite, varroa mite Insects: Common bed bug, emerald ash borer, gypsy moth, Japanese beetle, multicolored Asian lady beetle

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310 n STATE-BY-STATE OCCURRENCES OF INVASIVE MICROORGANISMS, FUNGI, AND ANIMALS Vertebrates Fish: Alewife, brown trout, mosquitofish, rainbow trout, sea lamprey Birds: Cattle Egret, European Starling, House Finch, House Sparrow, Rock Pigeon Mammals: Feral cat, feral pig, house mouse, Norway rat Wyoming Microorganisms: West Nile virus Fungi: Chytrid frog fungus, Dutch elm disease, white pine blister rust Invertebrates Annelid worms: European earthworms Mollusks: New Zealand mud snail Arachnids: Honeybee tracheal mite, varroa mite Insects: Common bed bug, multicolored Asian lady beetle Vertebrates Fish: Brown trout, mosquitofish, rainbow trout Birds: Cattle Egret, European Starling, House Sparrow, Rock Pigeon Mammals: Feral cat, feral horse, house mouse, Norway rat Commonwealth of Puerto Rico Fungi: Chytrid frog fungus Invertebrates Cnidarian: Australian spotted jellyfish Mollusks: Asian clam Insects: Red imported fire ant Vertebrates Fish: Brown trout, gizzard shad, mosquitofish, rainbow trout? Amphibians: Cuban treefrog Reptiles: Burmese python, green iguana Birds: Cattle Egret, European Starling, House Sparrow, Monk Parakeet, Rock Pigeon Mammals: Feral cat, feral goat, house mouse, Indian mongoose, Norway rat

n Glossary Achene. A small, dry, hard one-seed fruit. Adventive. Refers to an introduced species that has arrived in a new habitat or environment without the aid of humans and that has not established a self-replacing population. Aeciospore. A fungal spore produced in an aecium. Each spore has two nuclei and is part of a chain of spores. Aecium. The cuplike fruiting body of some rust fungi. Aerenchyma. Pithy respiratory tissue, common in stems of some aquatic plant species. Agnathan. Member of the class Agnatha, the jawless fish. Alate. Winged reproductive adult of a social insect, such as ants and termites. Alien (species). A nonnative species. A species found beyond its normal range limits. Synonyms: exotic, nonindigenous. Allee effect. The consequences of low population density when the presence of too few individuals greatly reduces reproductive success. Alleleopathy. Condition in which one plant or species exudes chemicals that prevent the growth of other plants in the immediate vicinity. Altricial. Refers to recently hatched birds or other newborn animals that have closed eyes and little or no down or fur, and that are unable to leave the nest and therefore must depend upon the parents for food. Anadromous. Refers to fish that spend most of their lives in salt water but ascend freshwater streams to spawn. Anecic. Refers to deep-burrowing earthworms that inhabit the lower layers of the soil. Annelid worm. Any member of the phylum Annelida, the segmented worms. Annual. A plant that germinates from seed, matures, and dies in one season. Apical (snail). The tip of a spiraling shell. Apomictic. Refers to a flower than does not require pollination to produce seed. Aquatic. Refers to a plant growing primarily or entirely in water, either rooted or free-floating. Aril. The fleshy coating around a seed. Arthropod. Member of the phylum Arthropoda, invertebrates with exoskeletons, segmented bodies, and jointed appendages. The phylum includes arachnids, insects, and crustaceans. Ascospore. A type of spore bearing a single copy of each chromosome formed by sexual reproduction in fungi in the Division/Phylum Ascomycetes. Asexual reproduction. The multiplication of individuals without the fusion of gametes. Can occur in fungi and animals through cell splitting, budding, cloning, or sporation. In plants, formation of new plants without the transfer of pollen. In some plants, new individuals can be generated vegetatively from parts of the parent plant. Auricle. Earlike appendage at the base of some leaves, which clasps the stem.

312 n GLOSSARY Awn. A bristle-shaped appendage on a grass. Axis. The central line of any organ, such as a stem. Barbel. Whiskerlike tactile organ in catfish and carp that houses taste glands and helps them to find food in murky water. Basidiospore. A spore bearing a single copy of each chromosome and found in fungi of the Division/Phylum Basidiomycetes. Beak (bivalve). The highest raised part of each valve, which is generally pointed and located near the hinge. Benthos. A collective term referring to organisms living on the seabed. Bergmann’s Rule. An ecogeographic pattern wherein the higher the latitude or colder the climate, the larger the body size of warmed-blooded animals compared to close relatives living at lower latitudes and/or in warmer climates. Biennial. A plant that lives for two years, usually flowering and setting seed in the second year. Bilabiate. Refers to a corolla, two-lipped. Biodiversity. The total variation and variability of life found in genes, species, communities, ecosystems, and landscapes. Biogeography. The science that studies the distribution patterns of species and the processes that determine those patterns. Biotype. A subset of a species with a particular set of genetic features. Bivalve. A mollusk, such as a clam or mussel, that has its body covered by two rigid shells joined by a hinge. Blade. The portion of the leaf that extends from the leaf sheath, flat, folded, or with rolled margins. Bolt. Rapid growth of flower stalk. Bract. A small scale-like leaf, usually associated with a flower. Bulbil. Small bulb, usually growing from leaf axils. Byssal threads. Filaments that some mollusks produce and use to fasten themselves to hard surfaces. Calyx. The leaf-like sepals that enclose the petals of a flower. Canker. A localized area of dead tissue on the trunk or branch of a woody plant. Cardinal teeth (bivalve). Ridges and grooves on the inner surfaces of both valves of a bivalve near the front end of the hinge that help hold the shells in alignment. Carton. Material made of undigested cellulose, mud, and termite saliva. Catadromous. Refers to fish that spend most of their lives in freshwater but migrate to the sea to breed. Chasmogamous. Refers to flowers that open to allow cross-pollination. Chitin. A strong, semitransparent, horny substance that is the main material composing the exoskeletons of arthropods and the internal structures of certain other invertebrates. Chlamydospore. Large, thick-walled resting spore of several kinds of certain fungi. It is the part of the life cycle that allows survival during unfavorable conditions, such as excessive drought or heat.

GLOSSARY n 313

Cilia. Hairlike structures used by some cells to move themselves or to move food particles. Clambering. Refers to shrubs or vines with stems that climb onto and over other plants. Cleistogamous. Refers to flowers that do not open and are self-pollinated as buds. Clitellum. Thickened, saddlelike section of the body of earthworms that secretes a viscous fluid in which the worm’s eggs are deposited. Colubrid. Any snake of the large and poorly defined group of nonvenomous snakes placed in the family Colubridae. Columella (snail). The central structural spine of coiled snail and whelk shells. Community (ecological). All species living in the same area or a subset of them, such as the bird community or the plant community. Compound. Refers to leaves that are divided into leaflets. Conidia. Asexual, nonmotile spores of a fungus such as chestnut blight. Contact. Refers to herbicides that kill only the plant portions contacted. Coppicing. Refers to trees that sprout many shoots from a cut stump. Corm. A type of bulb. Corolla. The petals of a flower. Corona. A distinct circular growth between the corolla and the stamens, especially in the milkweed family. Culm. Stem of a grass, usually hollow. Cuticle (insect). The exoskeleton, composed mostly of chitin. Cuticle (plant). A protective waxy coating produced by the outermost cells of a leaf or other aerial part of a plant. Cyme. A broad and flat-topped determinate flower cluster, with central flowers opening first. DBH (Diameter at breast height). Standard way of expressing the diameter of a living tree. There is no universal standard, however, as to what breast height is. In the United States, DBH is usually measured at a height of 1.4 m (about 4.5 ft.) above ground. Decumbent. Refers to a stem that is reclining or lying on the ground, but with the tip upright. Dehiscent. Refers to a seed capsule that opens, sometimes explosively. Determinate. Refers to when a branch or stem ceases to grow after flowering. Detritus. Organic debris composed of parts of plants, the remains of animals, and waste products that accumulates on the ground or moves into water bodies from surrounding terrestrial areas. Diapause. A suspension of development in response to adverse environmental conditions. Dioecious. Refers to male and female flowers being on different plants. Disjunct. A distribution pattern in which parts of the range are noncontiguous, i.e., separated geographically. Drupe. A fleshy, one-seeded fruit. Druplet is one part of a berry fruit. Ecology. The interrelationships among organisms and the nonliving aspects of the environment in which they live; the science that studies such interrelationships.

314 n GLOSSARY Ecosystem. The totality of living and nonliving elements in a given area that function as a unit to cycle nutrients and maintain a flow of energy. Ecotype. A population that is adapted to a particular environment and displays characteristics that set it apart from related populations but that has not evolved into a distinct species. Emergent. Refers to aquatic plants that grow primarily above the water surface. Entire. Refers to leaf margins that are smooth, not toothed or serrated. Epiphyte. A plant that physically lives on another but obtains no nutrients from the host. Bromeliads and tropical orchids are frequently epiphytic. The leaves of some epiphytic bromeliads fuse to form a tank in which water collects, creating prime breeding grounds for mosquitoes and some treefrogs. Erect. Growing upright, not sprawling or trailing. Established (species). A species not native to a geographic area and with a self-replacing population. Exotic (species). Any nonnative species. Synonyms: alien, nonnative, nonindigenous. Fasciated. Abnormal growth of a plant part, such as an inflorescence, causing it to be twisted or incurved. Also called crested. Floret. The individual flower of a grass, comprised of two bracts, the lemma and the palea, and the pistil and stamens. Also the individual flower of a composite. Follicle. A dry, dehiscent fruit or seed pod that splits open on the front. Forb. A broad-leaved, green-stemmed, nonwoody plant. One type of herb. Fouling (organism). Any organism that accumulates on solid surfaces in an aquatic environment and impedes the normal mechanical functioning of the equipment or host on which it resides. Frass. Fine, powdery material that wood-eating insects produce as waste after digesting plant matter. Fruiting body. Multicellular structure of fungi that carries spore-forming bodies. When the sexual stages of the life cycle are aerial, they are usually visible to the naked eye. Gamete. A mature sexual reproductive cell, either sperm, pollen, or egg, that fuses with another cell during fertilization to form a new organism. Genotype. The total complement of genes in an individual or an entire species. Gill rakes. Bony or cartilaginous, finger-like projections off the gill arch of fish that allow filter-feeders to retain food particles and keep solids from entering the gill cavity. Also called gill rakers. Glabrous. Smooth; not rough, fuzzy, or hairy. Glaucous. Covered with a bloom, a whitish substance that rubs off. Gloger’s Rule. An ecogeographic pattern in which warm-blooded animals in humid environments tend to have darker pigments in skin, feathers, or hair than close relatives living in drier environments. Glume. Bract on a grass that does not have associated flowers. Gonopodium. An anal fin that on some male live-bearing fish has been modified to allow passage of sperm and internal fertilization. Graminoid. Herbaceous plant that includes grasses, reeds, rushes, and sedges.

GLOSSARY n 315

Granivorous. Feeding on seeds. Gravid. Refers to a female carrying eggs or developing young; pregnant. Habitat. The place in which an organism lives and the physical attributes of that place. Halophyte. Plants adapted to salty conditions. Hammock. Slightly raised tree islands surrounded by other vegetation, usually sawgrass, in the Everglades. Harborage (insects). Shelter or refuge. Haustoria. The root-like, absorbing organs of a parasitic plant. Herb. A plant with no persistent woody stem above ground. Herbaceous. Hibernaculum. The wintering place that shelters hibernating bats. Holoparasite. A parasitic plant that can obtain nutrients and water in no way other than from a host plant. Host specific. Refers to a biological control that affects only the intended plant. Hyphae. Long, branching threads that are the main vegetative structural feature of many fungi. See also Mycelium. Indehiscent. Refers to a fruit that does not split open at maturity to release seeds. Indeterminate. Refers to when a branch or stem continues to grow after flowering. Inflorescence. Flower stalk and how the flowers are arranged. Injurious wildlife. Species of wild mammals, wild birds, fish, mollusks, crustaceans, amphibians, and reptiles listed under the auspices of the Lacey Act that the secretary of the interior has determined may be harmful to the health and welfare of humans; the interests of agriculture, horticulture, or forestry; and the welfare and survival of wildlife resources of the United States. Such species require a permit in order to be imported or transported between states. Instar. A developmental stage in larval insects that begins and ends with a molt until the individual is sexually mature. Often, but not always, morphological changes occur from one instar to the next. Introduced species. A species that has been transported, either deliberately or unintentionally, by humans to a location it had not previously occupied. Introduction. The transport and release into a free-living state of a nonnative species. Invasive species. (1) A nonnative species that is currently spreading rapidly or that has done so in the past; (2) “An alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health” (Executive Order 13112). Involucre. Whorl of small leaves or bracts beneath a flower or flower cluster, especially thistles. Irruption. A sudden, rapid increase in numbers in an animal population, usually accompanied by the migration of many individuals. Keratin. A fibrous structural material composed of protein in skin, hair, nails, feathers, and beaks of vertebrates. Lateral line. A sense organ in aquatic organisms such as fish and amphibians that is used to detect movement and vibration. Commonly visible as a faint line running lengthwise down each side.

316 n GLOSSARY Lateral teeth (bivalve). Elongated, interlocking projections along the hinge line of a shell that prevent the two valves from sliding against each other when the shell is closed. Lemma. The lower of the two bracts that enclose the flower in a grass. Lenticel. Corky cells in the bark of trees that allow air to penetrate into the interior. Ligule. Ring on the inside of a grass leaf where the blade meets the sheath. Lore (bird). The area between the eye and the bill on the side of the head Macroalgae. Large, multicellular algae. Seaweed. Macrophyte. Any plant large enough to be visible to the naked eye. Margins. The edges of leaves or leaflets. Membranous. Thin, parchment-like texture. Meristem. The growing point of a plant. Monocarpic. Refers to a plant in which the growing point of the plant becomes the flowering stem, and the plant dies after flowering. Monoecious. Refers to both female and male flowers on the same plant. Monospecific. Consisting of one species. Monotypic. Consisting of one genotype or ecotype, such as a clone. Mucilaginous. Soft, moist, sticky, or gel-like. Mycelium. A mass of branching, filamentous hyphae through which a fungus absorbs nutrients and decomposes plant material. Naı¨ve. Previously unexposed to a pathogen and therefore having no natural immunity. Native. In this encyclopedia, describes species, habitats, or ecosystems known to have existed in North America prior to European colonization. Considered by many to be the natural elements of a continent’s biodiversity that would occur even if humans had not settled the region. Native transplant. A species that is native to the country or region in question but has been transported beyond its natural range limits. Naturalized (species). Refers to a nonindigenous species that is able to sustain itself reproductively in the wild outside of cultivation, and has become a functioning member of a native ecosystem. Nitrogen fixer. A plant that, with the help of certain soil bacteria that form nodules on its roots, can utilize atmospheric nitrogen. Node. Joint in a stem, usually where the leaves grow. Nonindigenous (species). A species that is not native to the place in which it now occurs. Nonnative (species). An alien, exotic, or nonindigenous species. Noxious (weed). A plant specified by law as being especially undesirable, troublesome, and difficult to control. Nuisance (species). According to the Nonindigenous Nuisance Aquatic Prevention and Control Act of 1990, an alien aquatic species that “threatens the diversity or abundance of native species or the ecological stability of infested waters, or commercial, agricultural or recreational activities dependent upon such waters.”

GLOSSARY n 317

Nymph (insect). The immature form of insects that undergo a gradual and incomplete metamorphosis before reaching the adult stage. A nymph resembles the adult form and never enters a pupal stage. It becomes an adult after the final molt. Opercle. A bony plate that supports the gill covers of fishes, especially the most posterior one. Organelle. Any of the distinct structures within a cell that performs a specific and vital function. Outcompete. When a plant or animal displaces another plant or animal by being a better competitor for some resource. Palate (plant). A bulge in the lower lip of a figwort (Scrophulariaceae) flower that closes off the throat. Palea. The upper of the two bracts that enclose the flower in a grass. Palpus. A jointed organ for touching or tasting attached to a mouthpart in arthropods. Panicle. A loose, irregularly compound inflorescence with flowers on pedicels. Pantropical. Found throughout the tropics. Pappus. Appendage to a flower in the sunflower family (Asteraceaceae), such as a thistle, which may remain attached to the fruit; may be bristled, plume-like, or scaly. Paradioecious. Refers to male and female flowers occurring on separate plants, but any individual can develop flowers of either gender. Parietal callus. In some snails, a thickened deposit on the margin of the aperture and the wall of the body whorl closest to the central spine (columella). It is often smooth and glossy and may be adorned with raised ribs or wrinkles. Parthenogenesis. A form of asexual reproduction in which growth and development of embryos occurs without fertilization of the ovum by sperm. Pathway. The means by which a species arrives at a new region. Pedicel. Stalk that supports an individual flower or fruit. Peduncle. Stalk that supports a flower cluster. Perennial. A plant that lives for more than one season, although aerial parts may die back. Perigynium. The inflated sac, which encloses the ovary in Carex species. Petiole. A leaf stalk. pH. The measure of acidity or alkalinity of soil or water. Using a logarithmic scale, it describes the amount of hydrogen ions in the solution. Pharyngeal teeth (fish). Teeth in the throat located at the back of a fish’s head. Pheromone. Chemicals released by an organism into its environment to communicate with other members of its own species. Some pheromones are alarm signals, while others attract individuals to food or to a mate. Phloem. Plant tissues that conduct foods made in the leaves to all other parts of the plant. Photoperiod. The number of hours of daylight. Phreatophyte. Refers to plants with roots that extend into the water table. Phytoplankter. A tiny, usually microscopic plant that is part of the plankton.

318 n GLOSSARY Pinna. The primary division, or branch, of a pinnate leaf. Leaflets are on the pinna. Plural, pinnae. Pinnate. Describes compound leaves that have pairs of leaflets on either side of a stalk. Evenly pinnate leaves have an even number of paired leaflets and terminate in a pair. Oddly pinnate leaves have an uneven number of leaflets and terminate in a single leaflet. Pinnatifid. Describes leaves that resemble pinnately compound leaves, but with lobes that do not reach the midrib of the leaf. Plankton. A collective term referring to all organisms that drift in open water unable to move under their own power against tides and currents. Pollard. Describes the method of severely pruning tree limbs back to the trunk or to a main branch. Polychaete. A member of the Polychaete class of annelid worms characterized by having bristles on each body segment. Also called bristle worms and lugworms. Postemergent. Describes a herbicide that affects growing plants. Precocial. Referring to hatchlings or newborns that are born with their eyes open, fully feathered, or furred, and that leave the nest a short time after birth or hatching, Preemergent. Describes a herbicide that prevents seeds from germinating. Pronotum. In insects, the upper surface of the first segment of the thorax. Propagule. In animals, the minimum number of individuals of a species capable of colonizing a new area. This may be fertilized eggs, a mated female, a single male and a single female, or a whole group of organisms, depending upon the biological and behavioral requirements of the species. In plants, a propagule is whatever structure functions to reproduce the species, such as a seed, spore, stem, or root cutting. Protist. A microorganism that is either single-celled or multicellular, but lacking specialized tissues, and has the genetic information carried in a cell nucleus. Pubescence. Describes plant parts covered with soft, fine hairs. Pupa. In the development of those insects that undergo complete metamorphosis, the life stage that immediately precedes the adult stage. Some pupae remain inside the exoskeleton of the final larval instar, but others are encased in a cocoon or chrysalis. Pustule. A blister-like spot. Pycnia. A flask-shaped or conical fruiting body of a rust fungus that develops below the epidermis of the host and bears pycniospores. Pycniospore. A spore produced in a pycnia of a rust fungus. It fuses with a hypha of the opposite mating type to produce the sexual generation. Raceme. Inflorescence with all the individual flowers on a single axis. Rachilla. A small or secondary axis or rachis, especially the axis that bears florets in sedges and grasses. Rachis. An axis bearing flowers or leaflets. Recurved. Bent backward. Rhizoid (fungi). A structure that functions like a root to anchor the fungus and absorb nutrients. Rhizoid also releases enzymes that break down organic matter.

GLOSSARY n 319

Rhizome. A root structure below the soil surface, distinguished from a root by having nodes; can grow shoots that produce new plants. Also called a rootstock. Rootcrown. Top portion of a root, often containing dormant buds that sprout. Rosette. Arrangement of leaves radiating from a central point. Ruderal. Waste places. Samara. An indehiscent winged fruit. Saprotroph. Any organism that gains energy and nutrients from dead organic material. Savanna. Grassland with scattered trees. Scrambling. Sprawling or climbing over other plants. Sebaceous gland. A gland in the skin that secretes an oily substance to lubricate the skin and hair. Semievergreen. Remaining green only in warm climates or sheltered locations. Senesce. To grow old, turn brown. Senescence. Sepal. A leaf-like bract that encloses a flower or flower bud. Sepals form the calyx. Sessile (plant). Refers to flowers or leaves attached directly to stems, without pedicels or petioles. Settle (mollusks and crustaceans). The process by which larvae leave the plankton stage of their life and attach to a substrate. Sexual reproduction. The formation of new individuals from the union of two gametes, an ovum and a sperm. In the higher plants it takes places with the transfer of pollen from a male flower to a female flower. Sheath. A leaf structure that surrounds and encloses a grass stem. Shrub. Woody perennial smaller than a tree, usually with several stems. Silicle. A small seed pod in the Mustard family. Silique. A seed pod in the Mustard family. Simple. Refers to leaves that are not divided or compound. Species. A group of individuals of the same kind that can interbreed and produce viable offspring. Spike. A simple inflorescence with sessile flowers on a single axis. Also branch of a grass inflorescence. Spikelet. Secondary spike, especially a grass structure that includes glumes and florets, the cluster of grass flowers. Spirochete. A bacterium of the phylum Spirochaete, distinguished by its spirally twisted form. Sporangium. Structure in which spores are formed; spore case. Plural, sporangia. Sporation. Spore formation. Stellate. Refers to plant hairs, star-shaped. Stipule. The basal appendage of a petiole. Stolon. Root stem on the soil surface that roots at nodes; may produce new plants from sprouts; also called runners. Stromata. The connective tissue framework or support of cells or organisms.

320 n GLOSSARY Subdioecious. Male and female flowers usually restricted to separate plants. Submergent. Refers to aquatic plants, or parts, that grow completely underwater. Submersed. Refers to aquatic plants that grow primarily underwater. Flowering parts may be at or slightly above the water surface. May be free-floating or rooted. Subshrub. A shrub in which the upper branches die back during the unfavorable seasons. Substrate. Substance in which plants are rooted; can be soil, sand, alluvium, mud, or rock. Surfactant. Substance added to a herbicide to help the chemicals adhere to the foliage. Systemic. Refers to herbicides that are absorbed into plant tissues and translocated throughout the plant. Talus. Cone- or fan-shaped slope of loose rocks at the base of a cliff. Telium. The pimplelike cluster of spore cases that is produced by rust fungi. Ternate. In sets of three. Thorax (insects). The central of three main segments of an insect’s body: the segment between the head and the abdomen. Tree. A woody plant with one main trunk. Turion. A scaly, young shoot or sucker on a root or tuber. Two-ranked. Referring to alternate arrangement of leaves; leaves are on opposite sides of the stem, in the same geometric plane. Umbel. Often flat-topped inflorescence resembling an umbrella, with individual pedicels rising from a common point. Uredinia. A reddish, pimplelike structure on the tissue of a plant infected by a rust fungus. Vegetative reproduction. Formation of new plants from pieces of the parent plant, such as stems, leaves, rhizomes, and stolons. Also called asexual reproduction. Vent (reptile). Cloaca. The common cavity into which the intestinal, genital, and urinary tracts end. Vine. Plant whose stem requires support; can be trailing on the ground or climbing by twining, tendrils, or other means. Whorl. Arrangement of leaves in a circle around the stem, three or more leaves at one node. Xylem. Tissue that conducts water and dissolved minerals from the roots to all other parts of a plant, provides mechanical support, and forms the wood of trees and shrubs. Zooanthellae. Protozoans that live symbiotically in some jellyfishes as well as corals and other marine organisms. Zooid. One of the individual organisms composing a colonial animal, such as a bryozoan. Zooplankter. Any animal, single-celled or multicelled, that is part of the plankton. Zoospore. An asexual spore produced by some fungi that can move around by using a tail-like appendage (flagellum). Zygomorphic. In plants, irregular corollas that can be equally divided into mirror-image halves in only one plane, such as pea or orchid flowers.

n Index Page numbers in boldfaced type refer to a main entry in the encyclopedia and “t” indicates table. Acarapis woodi. See Honeybee Tracheal Mite Acclimatization societies, 238, 245 Acentria ephemerella, biological control (plants) Eurasian watermilfoil, 324–25 Aceria imperata, biological control (plants) cogongrass, 447 Aceria malherbae, biological control (plants) field bindweed, 609 Aceria salsolae, biological control (plants) prickly Russian thistle, 413 Achatina fulica. See Giant African Snail Acidotheres tristis. See Common Myna Acremonium zonaatum, biological control (plants) waterhyacinth, 342–43 Adedarach species. See Chinaberry Adelges tsugae. See Hemlock Woolly Adelgid Adoretus sinicus. See Chinese rose beetle Adventive species, xiv (v. 1) Aecidium mori var. broussonetia, biological control (plants) paper mulberry, 564 Aedes albopictus. See Asian Tiger Mosquito Aedes eagypti. See Yellow fever mosquito Aegopodium podagraria. See Goutweed African Clawed Frog, xxivt (v. 1), xxvt (v. 1), 18, 19, 201–5 state-by-state occurrences, 295, 296 African feathergrass, 460–61 noxious designation, 653, 665, 666, 668, 669, 670, 671, 691 African fountain grass. See Crimson Fountain Grass African foxtail grass. See Buffelgrass Africanized Honey Bee, xix (v. 1), xxvt (v. 1), 106–10 as varroa mite host, 103, 108 African pyle. See Giant Salvinia Agonopterix nervosa, biological control (plants) brooms, 501 Agreement on the Application of Sanitary and Phytosanitary Measures, 703 Agrilus aurichalceus. See rose stemgirdler Agrilus hyperici, biological control (plants) common St. Johnswort, 361

Agrilus planipennis. See Emerald Ash Borer Agropyron repens. See Quackgrass AHB. See Africanized Honey Bee Ailanthus. See Tree of Heaven Ailanthus altissima. See Tree of Heaven Ailanthus glandulosa. See Tree of Heaven Ailanthus peregrine. See Tree of Heaven Air potato, 607, 660 Aizoaceae, stone plant family, 383 Akala, 536, 538, 657 Akalakala, 536, 656 Akebia quinata. See Chocolate Vine Akepa, as affected by avian malaria, 248 Alabama jumper (earthworm), 49 ALB. See Asian Longhorned Beetle Albizia julibrissin. See Silk Tree Albizzia julibrissin. See Silk Tree Albonia peregrina. See Tree of Heaven Albugo. See white leaf rust Alelaila tree. See Chinaberry Aleppo grass. See Johnsongrass Alewife, xviii (v. 1), xxiiit (v. 1), 157–60, 190, 193 state-by-state occurrences, 296, 298–310 Alfalfa dodder, 611, 660 Alfalfa dwarf (disease), Glassy-Winged Sharpshooter as vector, 137 Alien Animals (Laycock), xxxi (v. 1) Alien, definition, xiii (v. 1) Alkali bulrush. See cosmopolitan bulrush Allegheny blackberry, 524, 656 Alleleopathy Australian pine, 542 chinaberry, 553 Chinese lespedeza, 352 dyer’s woad, 364 exotic bush honeysuckles, 506 Johnsongrass, 471 kikuyugrass, 480 lantana, 521 quackgrass, 488 tree of heaven, 588 yellow starthistle, 429 Alley cat. See Feral Cat

I-2 n INDEX Alliaria alliaria. See Garlic Mustard Alliaria officinalis. See Garlic Mustard Alliaria petiolata. See Garlic Mustard Allorhogas species, biological control (plants) velvet tree, 592 Alosa pseudoharengus. See Alewife Alternaria solani, tropical soda apple as host, 533 Altica carduorum, biological control (plants) Canada thistle, 348 Alvars, 639 Amberique bean, 623, 660 American alligator, 663 as potentially affected by Nile monitor, 228 and West Indian marsh grass, 491 American barberry, 512, 656 American beach grass, 432, 435, 653 American bittersweet, 630–31, 632, 660 American Bullfrog, xiii (v. 1), xviii (v. 1), xxvt (v. 1), xxvi (v. 1), 205–8 as chytrid frog fungus vector, 19 ISSG 100 worst invaders, 207, 711 state-by-state occurrences, 295, 296, 298, 299, 301, 303, 304, 306, 308, 309 American bumblebee, as varroa mite host, 103 American climbing fern, 598–99, 660 American crocodile, 663 as potentially affected by Nile monitor, 228 and West Indian Marshgrass, 491 American cupscale, 489, 653 American eel, 160, 183, 191 American elm, 23 cultivars, 25 American hogpeanut, 623, 660 American Robin, 661 and exotic bush honeysuckles, 506 and multiflora rose, 525 American wisteria, 645, 660 Aminopyralid, chemical control (plants) common St. Johnswort, 361 Ampelopsis brevipedunculata. See Porcelainberry Ampelopsis glandulosa var. brevipedunculata. See Porcelainberry Ampelopsis glandulosa ‘Elegans,’ 633, 634 Ampelopsis heterophylla. See Porcelainberry Amphibians, 201–14 ISSG 100 worst invaders, 711 Amur Honeysuckle 502–8, 614 noxious designation, 666, 668, 671, 692. See also Exotic Bush Honeysuckles Amur peppervine. See Porcelainberry Amynthas agrestis. See Alabama jumper Anabasis glomerata. See Halogeton

Anacardaceae. See sumac family Anchored waterhyacinth, 339, 649 noxious designation, 665, 666, 668, 669, 670, 671, 689 Andean pampas grass. See Jubata Grass Andes grass. See Jubata Grass Andropogon vimineum. See Japanese Stilt Grass Anecic worms, 50 Angle worm, 49. See European Earthworms Anisantha tectorum. See Cheatgrass Anitimicrobial chemicals, African Clawed Frog, 204 Anjan grass. See Buffelgrass Annelid worms, 48–53, 216 Anolis distichus. See Bark anole Anolis equestris. See Knight anole Anolis garmani. See Jamaican giant anole Anoplophora glabripennis. See Asian Longhorned Beetle Antelope bitterbrush, 442, 656 Anthonomus tenebrosus, biological control (plants), tropical soda apple, 534 Antiblemma acclinalis, biological control (plants) Koster’s curse, 518 Antitoxicum rossicum. See Pale Swallow-Wort Aphalara itadori, biological control (plants) Japanese knotweed, 390 Aphids, biological control (plants), 663 Canada thistle, 347 exotic bush honeysuckle, 507 giant reed, 466 Japanese hops, 621 kikuyugrass, 481 tropical soda apple, 634 Aphtae epizooticae, Wild Pig as host, 280 Apiaceae. See carrot family Apion fuscirostre, biological control (plants) brooms, 501 Apion species, biological control (plants) velvet tree, 592 Apion ulicis, biological control (plants) gorse, 511 Apis mellifera scutellata. See Africanized Honey Bee Aplocera plagiata, biological control (plants) common St. Johnswort, 361 Aporrectodea caliginosa. See European Earthworms Applesnail. See Golden Applesnail Apthona species, biological control (plants) leafy spurge, 398 Aquarium watermoss. See Giant Salvinia Aquatic invertebrates, ISSG 100 worst invaders, 711

INDEX n I-3 Aquatic plants, 321–43 American species invasive abroad, 696 ISSG 100 worst invaders, 710 noxious designation, 689 Aquatic soda apple. See wetlands nightshade Aquatic weeds, grass carp control of, 173, 174 Arachnids, 99–106 Araliacaeae. See ginseng family Archanara geminipuncta, biological control (plants) common reed, 451 Archips asiaticus, biological control (plants) chocolate vine, 596 Argentine Ant, xxii (v. 1), xxvt (v. 1), 110–13 ISSG 100 worst invaders, 711 state-by-state occurrences, 295–310 Aristolochia. See pipevine and wooly Duchman’s pipe Arizona cottontop, 436–37, 653 Arizona wheatgrass, 483, 653 Artimpaza argenteonota, biological control (plants) Asiatic colubrina, 496 Artipus floridanus, biological control (plants) Australian pine, 543 Arundo. See Giant Reed Arundo donax. See Giant Reed Arundo selloana. See Pampas Grass Arundo versicolor. See Giant Reed Asclepiadaceae. See milkweed family Asian applesnail. See Chinese Mystery Snail Asian bittersweet. See Oriental Bittersweet Asian Clam, xxiiit (v. 1), xxix (v. 1), 53–56, 77 state-by-state occurrences, 295–310 Asian euonymus scale, biological control (plants) winter creeper, 643 Asian Green Mussel, xxvt (v. 1), 56–58 state-by-state occurrences, 297, 298, 307 Asian gypsy moth, 138 Asian honey bee, as varroa mite host, 102 Asian lady beetle. See Multicolored Asian Lady Beetle Asian Longhorned Beetle, xix (v. 1), xxvt (v. 1), 113–16 ISSG 100 worst invaders, 711 state-by-state occurrences, 299, 301, 304 Asian nakedwood. See Asiatic Colubrina Asian rapa whelk. See Veined Rapa Whelk Asian snakeroot. See Asiatic Colubrina Asian Swamp Eel, 160–62 state-by-state occurrences, 297, 298, 304 Asian tapeworm, grass carp as host, 174

Asian Tiger Mosquito, xxiv (v. 1), xxvt (v. 1), 116–20 ISSG 100 worst invaders, 711 state-by-state occurrences, 295–310 Asian water monitor, 226 Asiatic bittersweet. See Oriental Bittersweet Asiatic clam. See Asian Clam Asiatic Colubrina, 493–96 impacts, 683 noxious designation, 666, 692 pathways of introduction, 675, 677 uses of, 496 Asiatic Sand Sedge, 432–35 impacts, 683 noxious designation, 666, 668, 691 pathways of introduction, 433, 675, 676 Asiatic tear-thumb. See Mile-A-Minute Asteraceae. See aster family; sunflower family Athel tamarisk, 581, 583, 658 Atlantic cordgrass. See Cordgrasses and Their Hybrids Atlantic ivy, 603–4, 660 Atlantic shipworm. See Naval Shipworm Atlantic wisteria, 645, 660 Atomacera petroa, biological control (plants) velvet tree, 592 Atrazine, chemical control (plants) cheatgrass, 443 medusahead, 485 mile-a-minute, 628 Australian Pine, 540–44 and Asiatic colubrina, 495 impacts, 681, 682, 684 noxious designation, 666, 692 pathways of introduction, 541, 675 uses of, 543 Australian pine borer, biological control (plants) Australian pine, 543 Australian river oak, 540, 541, 542, 658 Australian Spotted Jellyfish, 45–48 state-by-state occurrences, 295, 297, 298, 300, 302, 310 Austromusotima camptozonale, biological control (plants) climbing ferns, 601 Autumn olive, 568, 570 noxious designation, 570, 668, 669, 672, 692 Avian Malaria, xix (v. 1), xxvii (v. 1), 1–3, 24, 248 bird reservoir, 234 state-by-state occurrences, 298 Awapuhi kahili. See Kahili Ginger Azolla species, 327

I-4 n INDEX Bacterial leaf scorch (Xylalla fastidiosa), 22, 137 Bacterial leaf scorch, and Dutch Elm Disease, 22 English Ivy as host, 605 Bagous affinis, biological control (plants) hydrilla, 334 Bagpod, 528, 650 Bahamian brown anole. See Brown Anole Bald brome, 440, 653 noxious designation, 666, 691 Ball nut. See Water Chestnut Banded mystery snail, 59 Bangasternus orientalis, biological control (plants) yellow starthistle, 430 Banker horse. See Feral Horse Barberry family, 512 Barbwire Russian thistle, 411, 650 noxious designation, 665, 666, 690 Bark anole, 215 Barley, 483, 653 Basal bark application, herbicides, xx (v. 2) Basiliscus vittatus. See Brown basilisk Bat nut. See devil pod Batrachochytrium dendrobatidis. See Chytrid Frog Fungus Bat White-Nose Syndrome Fungus, xix (v. 1), 11–14 state-by-state occurrences, 297, 301–2, 304, 306, 308, 309 Bay cedar, 495, 658 Beach clustervine, 546, 660 Beach layia, 386, 650 Beach panic grass, 432, 435, 653 Beach she-oak. See Australian pine Beachstar, 546, 654 Bead tree. See Chinaberry Bean aphid, Canada thistle host, 347 Bean stalk borer, Canada thistle host, 347 Bearberry honeysuckle, 505, 656 Beardless wheatgrass, 487, 654 Bedbug. See Common Bed Bug Bee colonies destruction, by varroa mite, 104–5 Beefwood. See Australian pine Beetles, biological control (plants) Asiatic colubrina, 496 Brazilian peppertree, 547–48 Canada thistle, 348 climbing ferns, 601 common St. Johnswort, 361 garlic mustard, 372 hydrilla, 334 Japanese hops, 621 Japanese knotwood, 390 Koster’s curse, 518

kudzu, 625 leafy spurge, 398–99 melaleuca, 561 purple loosestrife, 417 rattlebox, 529 tamarisk, 585 toadflax, 426 tropical soda apple, 534 velvet tree, 592 water chestnut, 338 Begomovirus. See tobacco leaf curl Bell’s honeysuckle, 502–8 noxious designation, 666, 668, 669, 691, 692. See also Exotic Bush Honeysuckles Belut eel. See Asian Swamp Eel Berberidaceae. See barberry family Berberis japonica. See Japanese Barberry Berberis sinensis. See Japanese Barberry Berberis thunbergia var. atropurpurea. See Japanese Barberry Berberis thunbergii. See Japanese Barberry Berberis x ottawensis, 512 Bergmann’s Rule, xxxi (v. 1), 312, 714 Bermuda grass, 479, 654 Big Cypress National Preserve West Indian marsh grass, 490 melaleuca, 559 Big Cypress National Preserve, spotted tilapia, 197 Burmese python, 218 melaleuca, 559 Big eye herring. See Alewife Bighead. See hyperparathyroidism Bighead Carp, xxvt (v. 1), 163–66, 195 state-by-state occurrences, 295–300, 302–3, 306–9 Bignonia tomentosa. See Princess Tree Big sage. See Lantana Big taper. See Common Mullein Biogeography, xiii (v. 1), xxxii (v. 1) Biological control (plants). See species entries Birds, 228–59 Bishop’s goutweed. See Goutweed Bishop’s weed. See Goutweed Bitter panicum, 432 Black acacia. See Rattlebox Black carp, 172 Black dog-strangle vine. See Black Swallow-Wort Blackfin cisco, 193 Black-hooded Parakeet. See Nanday Conure Black imported fire ant, 152 Black-legged tick as Lyme disease vector, 4, 5, 6 Black mangrove cichlid. See Spotted Tilapia

INDEX n I-5 Black Rat, xviii (v. 1), xxvit (v. 1), 259–62, 287 ISSG 100 worst invaders, 261, 712 state-by-state occurrences, 295–310 Blacksage. See Lantana Black snail. See Chinese Mystery Snail Black spinytail iguana, 222–23 Black stem grain rust, 513 Black Swallow-Wort, 636–40 impacts, 678, 680, 684 noxious designation, 666, 668, 669, 671, 693. See also Swallow-Worts Bladderpod. See bagpod Blady grass. See Cogongrass Blue toadflax. See Canada toadflax BMSB. See Brown Marmorated Stink Bug Bohemian knotweed. See giant knotweed Boiga irregularis. See Brown tree snake Bootanelleus orientalis, biological control (plants) Australian pine, 543 Boreioglycaspis melaleucae, biological control (plants) melaleuca, 561 Borrelia burgdorferi. See Lyme Disease bacterium Boston ivy, 603, 633, 660 Bothriocephalus opsarichthydis, 174 Botrylloides diagensis, 40 Botrylloides perspicuum, 40 Botrylloides violaceus. See Chain Tunicate Botryllus schlosseri, 40 Botrytis cinerea, biological control (plants) fire tree, 557 Botrytis cinerea, fire tree control, 557 Bowfin, 182, 183 Branch herring. See Alewife Brachypterolus pulicarius, biological control (plants) toadflax, 426 Branched tearthumb, 600, 650 Brassicaceae. See mustard family Brazilian elodea. See Brazilian waterweed Brazilian oak, 540, 541–42, 543, 658 Brazilian Peppertree, 495, 544–48, 560 impacts, 682, 684, 685 ISSG 100 worst invaders, 710 noxious designation, 666, 671, 692 pathways of introduction, 673 uses of, 547 Brazilian satintail, 445, 654 noxious designation, 665, 666, 668, 669, 670, 671, 691 Brazilian waterhyacinth, 440, 649 Brazilian waterweed, 332, 334, 649 Breea arvensis. See Canada Thistle Breea incana. See Canada Thistle

Bridal broom, 498, 656 Bristletips, 515, 589–90, 656 British Petroleum oil spill (2010), 329 Broadleaf toadflax, 424, 650 Broadleaved pepperweed. See Perennial Pepperweed Broad-leaved toadflax. See Dalmatian Toadflax Broghammerus reticulates, 220 Bromacil, chemical control (plants) Brazilian peppertree, 547 Bromeliads, 495, 660, 661 Bromus tectorum. See Cheatgrass Broncograss. See Cheatgrass Broomleaf toadflax, 424, 650 Brooms, 496–502, 509 impacts, 679, 681, 683 noxious designation, 666, 667, 670, 671, 692 pathways of introduction, 673, 675, 676 uses of, 502 Brotogeris chiriri. See Yellow-chevroned Parakeet Brotogeris versicolurus. See White-winged Parakeet Broussonetia papyrifera. See Paper Mulberry Brown Anole, xviii (v. 1), 214–17 state-by-state occurrences, 297, 298 Brown basilisk, 223 Brown Marmorated Stink Bug, xix (v. 1), xxvt (v. 1), xxx (v. 1), 120–23 state-by-state occurrences, 296, 297, 304–6, 307, 309 Brown rat. See Norway Rat Brown tree snake, xxiv (v. 1), xxvii (v. 1), 210 Brown Trout, xxivt (v. 1), 159, 166–68, 185 ISSG 100 worst invaders, 168, 711 state-by-state occurrences, 295–310 Bruchus atronotatus, biological control (plants) Brazilian peppertree, 548 Bryozoans, 36–38 Bubulcus ibis. See Cattle Egret Buckthorn family, 493 Buckwheat family, 387, 626 Budgerigars, 250 Buffalobur, 533, 650 noxious designation, 667, 670, 671, 690 Buff-backed heron. See Cattle Egret Buffelgrass, 435–39 impacts, 679, 683 noxious designation, 665, 691 pathways of introduction, 675 Bulb panicgrass, 470, 654 Bulbous buttercup. See Fig Buttercup

I-6 n INDEX Bull thistle, 345–46, 348–49, 401, 403, 650 noxious designation, 666, 667, 668, 669, 670, 671, 690 Burbot, 182, 183 Bur cucumber, 619, 660 Bureau of Land Management (BLM) feral burros, 262, 264–65 feral horses, 273, 274–75 Burgdorfer, Dr. Willy, 5 Burmese Python, xviii (v. 1), xxivt (v. 1), 217–21 state-by-state occurrences, 297, 310 Burning, physical control (plants) Australian pine, 543 Canada thistle, 348 cheatgrass, 442–43 Chinese lespedeza, 352 common reed, 450–51 English ivy, 605 exotic bush honeysuckles, 506 garlic mustard, 371 giant reed, 465 gorse, 511 Japanese barberry, 514 Japanese dodder, 613 Japanese stilt grass, 469 medusahead, 484 quackgrass, 488 tamarisk, 584 tree of heaven, 588 yellow starthistle, 430 Burning bush, 380, 641, 643, 650, 656 noxious designation, 666, 660, 671, 690 pathways of introduction, 673 Bursting heart, 641, 643, 656 Bush currant. See Velvet Tree Bush honeysuckles. See Exotic Bush Honeysuckles Bush morning glory. See western morning glory Bush muhly, 437, 654 Bushy white solanum. See turkey berry Butter and eggs. See Yellow Toadflax Buttercup family, 366 Butterflies and Canada thistle, 348 and garlic mustard, 371 and Japanese stiltgrass, 468, and swallow-worts, 639 Butterflies, biological control (plants) fire tree, 557 garlic mustard, 371 Bythotrephes cederstroemi, 96 Bythotrephes longimanus. See Spiny Water Flea

California broom, 498 California Clapper Rail, 661 and cordgrass, 457 California cordgrass, 453, 454–55, 456, 457, 654. See also Cordgrasses and Their Hybrids California peppertree. See Peruvian peppertree California satintail, 445, 654 noxious designation, 666, 691 Californian thistle. See Canada Thistle Calophasia lunula, biological control (plants) toadflax, 426 Caloptilla sp. nr. schinella, biological control (plants) fire tree, 557 Camasey. See Koster’s Curse Canada germander, 414, 650 Canada Thistle, 344–49, 401 impacts, 678, 679, 682, 685 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 690 pathways of introduction, 677 Canada thistle stem weevil, xxiv (v. 1), 348 Canada toadflax, 424, 650 Canadian honeysuckles, 505, 656 Canadian waterweed, 332, 649 Canary Island St. Johnswort, 359, 656 Canby’s mountain-lover, 643, 656 Candleberry myrtle. See Fire Tree Cane. See Common Reed Cane ti, 515, 589–90, 656 Cane tibouchina. See cane ti Cannabidaceae. See hemp family Caper spurge, 396, 650 Capra hircus. See Feral Goat Caprifoliaceae. See Honeysuckle family Carcinus maenas. See Green Crab Carderia draba. See Hoary Cress Cardaria latifolia. See Perennial Pepperweed Carduus acanthoides. See plumeless thistle Carduus arvensis. See Canada Thistle Carduus nutans. See Musk Thistle Carduus pycnocephalus. See Italian thistle Carduus species, 344, 345, 399–404, 651, 652 noxious designation, 605, 607 pathways of introduction, 677. See also Musk Thistle Carduus tenuflorus. See slender-flowered thistle Carex kobomugi. See Asiatic Sand Sedge Caribbean fruit fly, 663 strawberry guava as host, 578, 579 Carolina horsenettle, 533, 650 noxious designation, 665, 666, 667, 669, 690

INDEX n I-7 Carolina Parakeet, xxix (v. 1), 251 Carpobrotus edulis. See Ice Plant Carpodacus mexicanus. See House Finch Carposina bullata, biological control (plants) Koster’s curse, 518 Carrizo. See Giant Reed Carrot family, 372, 376 Carrot weed. See Carrotwood Carrotwood, 548–51 impacts, 684 noxious designation, 666, 692 pathways of introduction, 673, 676 Cartwheel-flower. See Giant Hogweed Cassida rubiginosa, biological control (plants) Canada thistle, 348 Casuarina. See Australian Pine Casuarinaceae. See casuarina family Casuarina equisetifolia. See Australian Pine Casuarina litorea. See Australian Pine Casuarina littorea. See Australian Pine Casuarina family, 540 Catalpa, 566, 659 Caterpillars, biological control (plants) giant reed, 466 Japanese stiltgrass, 468 lantana, 521 Cat facing, fruit deformation, 122 Cattle forage for, 437, 441, 445, 470, 479, 480, 489 Johnsongrass, 472 leafy spurge, 398 plants toxic to, common St. Johnswort, 360 toadflax, 425, 521 Cattle Egret, xiv (v. 1), xxi (v. 1), 228–32 state-by-state occurrences, 295–310 Cattley guava, 576 Cayuga Lake, and Eurasian watermilfoil, 325 Celandine, 367, 650 Celandine poppy, 367, 650 Celastraceae. See staff-tree family; staff-vine family Celastrus articulatus. See Oriental Bittersweet Celastrus orbiculatus. See Oriental Bittersweet Celastrus sepiarius. See Asiatic Colubrina Cenchrus ciliaris. See Buffelgrass Cenchrus glaucus. See Buffelgrass Cenchrus setaceus. See Crimson Fountain Grass Centaurea biebersteinii. See Spotted Knapweed Centaurea maculosa. See Spotted Knapweed Centaurea solstitialis. See Yellow Starthistle Centaurea stoebe. See Spotted Knapweed Ceonothus asiaticus. See Asiatic Colubrina

Ceonothus capsularis. See Asiatic Colubrina Cercopagis pengoi. See Fishhook water flea Cercospora rodmanii, biological control (plants) waterhyacinth, 343 Ceutrhynchus litura. See Canada thistle stem weevil Ceutrhynchus species, biological control (plants) garlic mustard, 372 Ceutrhynchus trimaculatus, biological control (plants) musk thistle, 403 Chaetococcus phragmitis. See legless red mealybug Chaetorellia species, biological control (plants) yellow starthistle, 431 Chain sea squirt. See Chain Tunicate Chain Tunicate, xxiv (v. 1), xxvt (v. 1), 39–41, 42 state-by-state occurrences, 295–97, 300, 301, 303, 304, 306, 308, 309 Chamaespecia species. See clearwing moths Channa argus. See Northern Snakehead Channeled apple snail. See Golden Apple Snail Chaparral false bindweed. See western morning glory Character displacement, feeding adaptation, 243 Charru mussel, 56 Cheatgrass, 439–43 impacts, 678, 679, 685 and medusahead, 484 noxious designation, 666, 691 pathways of introduction, 676, 677 uses of, 443 Cheeseberry. See Yellow Himalayan Raspberry Cheilosia corydon, biological control (plants) musk thistle, 403 Chemical control (plants). See species entries Chenopodiaceae. See goosefoot family Cherokee rose, 523, 656 pathways of introduction, 673 Cherry guava. See Strawbery Guava Chestnut bark disease fungus. See Chestnut Blight Fungus Chestnut Blight Fungus, xxvit (v. 1), xxviii (v. 1), 14–17, 34 state-by-state occurrences, 295–310 Chewing disease. See nigropalallidal encephalomalacia Chinche. See Common Bed Bug Chilean iceplant. See sea fig Chilo phragmitella, biological control (plants) common reed, 451 Chinaberry, 551–54 impacts, 681, 684 noxious designation, 692

I-8 n INDEX pathways of introduction, 673 uses of, 554 China tree. See Chinaberry Chinese bush clover. See Chinese Lespedeza Chinese-glysine. See Wisteria Chinese honeysuckle, 614, 660. See also Japanese Honeysuckle Chinese Lespedeza, 349–53 impacts, 680, 682 noxious designation, 666, 667, 690 pathways of introduction, 676 Chinese Mitten Crab, xxiiit (v. 1), 86–89 ISSG 100 worst invaders, 711 state-by-state occurrences, 296 Chinese Mystery Snail, xxiiit (v. 1), 58–61 state-by-state occurrences, 295–97, 299–310 Chinese packing grass. See Japanese Stilt Grass Chinese rose beetle, biological control (plants) velvet tree, 592 Chinese sumac. See Tree of Heaven Chinese tamarisk. See Tamarisk Chinese turtledove, and lantana, 520, 661 Chinese wisteria. See Wisteria. See also Rattlebox Chinese yam, 603, 607, 660 Chlopyralid, chemical control (plants) wisteria, 647 Chlorflurenol, chemical control (plants) ice plant and crystalline ice plant, 386 Chlorsulfuron, chemical control (plants) Canada thistle, 348 dyer’s woad, 365 pepperweed and hoary cress, 409 Chocolate Vine, 594–97 impacts, 684 pathways of introduction, 673 uses of, 597 Christmasberry. See Brazilian Peppertree Chukar Partridge, 661 and cheatgrass, 443 and Medusahead, 484 Chrysobothris tranquebarica. See Australian pine borer Chrysolina species, biological control (plants) common St. Johnswort, 361 Chytonix segregate, biological control (plants) Japanese hops, 621 Chytrid fungus. See Chytrid Frog Fungus Chytrid Frog Fungus, xv (v. 1), 13, 18–21 African clawed frog as host, 204 American bullfrog as host, 207 state-by-state occurrences, 295–10 Chytridomycosis, 13, 204, 207 Cicadallid cotton pest, and Japanese honeysuckle, 617

Cichla ocellaris. See Peacock cichlid Cimex lectularius. See Common Bed Bug Cimex hemipterus, 124 Cinnamon vine, 603, 660 Cipangopaludina chinensis malleata. See Chinese Mystery Snail Cipangopaludina japonica. See Japanese mystery snail Cirsium arvense. See Canada Thistle Cirsium setosum. See Canada Thistle Cirsium species, 401 Cirsium vulgare. See bull thistle Cissus brevipedunculata. See Porcelainberry Clarias batrachus. See Walking Catfish Clastoptera undula, biological control (plants) Australian pine, 543 Clearwing moths, biological control (plants) leafy spurge, 398 Cleonis pigra, Canada thistle control, 349 Clethodim, chemical control (plants) quackgrass, 488 Cletus schmidti, biological control (plants) mile-a-minute, 629 Clidemia. See Koster’s Curse Clidemia crenata. See Koster’s Curse Clidemia elegans. See Koster’s Curse Clidemia hirta. See Koster’s Curse Climbing euonymus. See Winter Creeper Climbing fern family, 597 Climbing ferns, 597–602 impacts, 680, 684 noxious designation, 665, 667, 693 pathways of introduction, 673 Climbing milkweed. See Black Swallow-Wort Climbing nightshade, 532, 637, 660 Climbing prairie rose, 524, 656 Climbing spindleberry. See Oriental Bittersweet Clitocybe tabescens, biological control (plants) Australian pine, 543 Clopyralid chemical control (plants) Canada thistle, 348 Chinese lespedeza, 352 common mullein, 352 spotted knapweed, 421 yellow strarthistle, 430 Clusiaceae. See mangosteen family Cnidarians, 45–48 Coachella Valley Preserve tamarisk eradication, 584 Coastal sand spurge, 434, 650 Coast she-oak. See Australian Pine Cobicula fluminea. See Asian Clam Coccinella septempunctata. See Seven-spotted lady beetle

INDEX n I-9 Cochlearia draba. See Hoary Cress Cockroach berry, 532–33, 656 Cocostroma myconae, biological control (plants) velvet tree, 592 Codium fragile tomentosoides. See Dead man’s fingers Coffee colubrina, 493, 656 Cogon grass. See Cogongrass Cogongrass, 443–47 impacts, 679, 683 pathways of introduction, 675 ISSG 100 worst invaders, 710 noxious designation, 665, 666, 667, 668, 669, 670, 671, 691 Colchis ivy, 604, 660 Coleophora klimeschiella, biological control (plants) prickly Russian thistle, 413 Coleophora parthenica, biological control (plants) halogeton, 383 prickly Russian thistle, 413 Colletotrichum gloesporioides, biological control (plants) Koster’s curse, 518 kudzu, 625 Colletotrichum gloesporioides f. sp. miconiae, biological control (plants) velvet tree, 592 Colonial ascidian. See Colonial Tunicate Colonial sea squirt. See Colonial Tunicate Colonial Tunicate, xxiv (v. 1), xxvt (v. 1), 42–45 state-by-state occurrences, 296, 300, 303, 304, 306, 309 Colorado potato beetle, and tropical soda apple as host, 533–34, 663 Colubrina asiatica. See Asiatic Colubrina Columba livia. See Rock Pigeon Columnar cactus, 495, 658 Common barberry, 512–13, 656 noxious designation, 666, 668, 669, 692 Common Bed Bug, xix (v. 1), xxvt (v. 1), xxvt (v. 1), 123–27 state-by-state occurrences, 295–310 Common colubrina. See Asiatic Colubrina Common coqui. See Coqui Common cordgrass. See Cordgrasses and Their Hybrids; noxious designation, 670, 671, 691; pathways of introduction, 675 Common dodder, 611, 660 Common elderberry, 374, 551, 656 Common goatweed. See Common St. Johnswort Common gorse. See Gorse Common guava, 577, 578, 579, 659

Common hops, 619, 621, 660 Common hornwort. See coontail Common ice plant. See Crystalline Ice Plant Common iguana. See Green Iguana Common Mullein, xiii (v. 2), 353–57 impacts, 682, 685 pathways of introduction, 674, 675 noxious designation, 666, 667, 690 uses of, 357 Common Myna, xxiiit (v. 1), 1, 232–34 ISSG 100 worst invaders, 234, 712 lantana, 520 state-by-state occurrences, 297 strawberry guava, 578 and velvet tree, 591 Common parsnip, 373, 650 Common Periwinkle, 61–63 state-by-state occurrences, 297, 300, 301, 304, 306 Common pigeon. See Rock Pigeon Common platanna. See African Clawed Frog Common Reed, 447–51 and Giant Reed, 463 impacts, 683 noxious designation, 665, 666, 668, 670, 671, 691 pathways of introduction, 677 uses of, 451 Common saltwort. See Prickly Russian Thistle Common salvinia, 327, 649, 328, 329 Common St. Johnswort, 358–62 impacts, 678, 679, 680, 682 in medicine, 361 noxious designation, 666, 668, 669, 670, 671, 672 pathways of introduction, 675 Common toadflax. See Yellow Toadflax Contact herbicides, xx (v. 2) Convolvulaceae. See morning glory family Convolvulus ambigens. See Field Bindweed Convolvulus arvensis. See Field Bindweed Convolvulus incanus. See Field Bindweed Coontail, 322, 649 Copal. See Brazilian Peppertree Copal-tree. See Tree of Heaven Copper chelate, chemical control (plants) waterhyacinth, 342 Copper sulfate biological control (plants) waterhyacinth, 342 Coptotermes formosanus. See Formosan Subterranean Termite Coqui, xxvi (v. 1), xxx (v. 1), 208–11 ISSG 100 worst invaders, 210, 711 state-by-state occurrences, 297, 298

I-10 n INDEX Coquı´ comu´n. See Coqui Coral honeysuckle, 615, 641, 660 Coralberry, 505, 656 Cordgrass. See Cordgrasses and Their Hybrids Cordgrasses and Their Hybrids, 63, 274, 293, 452–56 American species invasive abroad, 696 impacts, 682, 683 noxious designation, 670, 671, 691, 692 pathways of introduction, 675, 676, 677 Corn bind. See Field Bindweed Corn thistle. See Canada Thistle Cortaderia. See Jubata Grass Cortaderia argentea. See Pampas Grass Cortaderia atacamensis. See Jubata Grass Cortaderia dioica. See Pampas Grass Cortaderia jubata. See Jubata Grass Cortaderia selloana. See Pampas Grass Cosmopolitan bulrush, 455, 654 Cotton States Exposition (1884), Waterhyacinth introduction, 340 Couch grass. See Quackgrass Council of Europe, and Water Chestnut, 338 Cow parsnip. See common parsnip Coypu. See Nutria Crasimorpha infuscate, biological control (plants) Brazilian peppertree, 548 Crassostrea gigas. See Japanese oyster Crater Lake National Park, and white pine blister rust, 34 Crawdad. See Rusty Crayfish Crawfish. See Rusty Crayfish Cream lily. See yellow ginger Creeper. See Porcelainberry Creeping Charlie. See field bindweed; ground ivy Creeping Jenny. See field bindweed Creeping thistle. See Canada Thistle Creeping wild rye. See Quackgrass Crested wheatgrass, 485, 487, 654 Cricotopus myriophylli. See milfoil midge Crimson beauty. See Japanese Knotweed Crimson bottlebrush, 558, 657 Crimson Fountain Grass, 458–62 noxious designation, 667, 691 pathways of introduction, 673 Crinkleroot, 371, 650 Cristulariella pyramidalis. See zonate leafspot Cronartium ribicola. See White Pine Blister Rust Crustaceans, 86–99 American species invasive abroad, 696 Cryphonectria parasitica. See Chestnut Blight Fungus Cryophytum crystallinum. See Crystalline Ice Plant

Crystalline Ice Plant, 383–87 impacts, 682 noxious designation, 690 pathways of introduction, 677 Ctenopharyngodon idella. See Grass Carp Ctenosaurus similis. See Black spinytail iguana Cuban brown anole. See Brown Anole Cuban nakedwood, 493, 657 Cuban Treefrog, xx (v. 1), xxviii (v. 1), xxxii (v. 1), 211–14, 227 state-by-state occurrences, 297, 310 Cucullia verbasci. See mullein moth Cucumber, 619 Culex quinquefasciatus. See Southern house mosquito Cultivation, physical control (plants). See tilling Cupania anacardioides. See Carrotwood Cupania anacardioides var. parvifolia. See Carrotwood Cupaniopsis anacardioides. See Carrotwood Currants, White Pine Blister Rust alternate host, 30, 32, 34 Curvulara lunata, biological control (plants) West Indian marsh grass, 492 Cuscutaceae family. See morning glory family Cuscuta japonica. See Japanese Dodder Cutleaf toothwart, 371, 650 Cutting or mowing, physical control (plants) brooms, 501 cheatgrass, 442 chocolate vine, 596 dyer’s woad, 365 English ivy, 605 giant reed, 465 gorse, 511 Japanese barberry, 514 Japanese dodder, 613 Japanese hops, 621 Japanese knotweed, 390 Japanese stilt grass, 468–69 Johnsongrass, 472 kudzu, 625 mile-a-minute, 628 multiflora rose, 525 oriental bittersweet, 632 rattlebox, 529 swallow-worts, 639 toadflax, 426 winter creeper, 643 wisteria, 647 yellow starthistle, 430 Cyanophyllum magnificum. See Velvet Tree Cygnus olor. See Mute Swan Cynanchum medium. See Pale Swallow-Wort

INDEX n I-11 Cynanchum rossicum. See Pale Swallow-Wort Cyperaceae. See sedge family Cyphocleonus achates, biological control (plants) spotted knapweed, 421 Cypress spurge, 396, 650 Cytisus monspessulana. See French Broom Cytisus scoparius. See Scotch Broom Cytisus striatus. See Portuguese Broom Crytobagous salviniae, biological control (plants) giant salvinia, 330 Dalmatian toadflax, 421–26 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 690 pathways of introduction, 674 Dark-green white-eye, 246 Daubentonia punicea. See Rattlebox Davis Pond Freshwater Diversion Project giant salvinia, 329 Dead man’s fingers (green algae), 37 Deer, and leafy spurge, 397 Deer mice, 281, 662 Deer tick, as Lyme disease vector, 4, 5, 6 Deformed wing virus (DWV), bee virus, 105 Dendrobaena octaedra. See European Earthworms Dendryphiella broussonetiae, biological control (plants) paper mulberry, 564 Dengue fever, xix (v. 1), xx (v. 1), 7, 119 Dense-flowered cordgrass, noxious designation, 671, 691 pathways of introduction, 676, 677. See also Cordgrasses and Their Hybrids Depressed shrubverbena. See pineland lantana Devil firefish, 175, 176, 176 Devil pod, 336, 649 Devil’s apple. See cockroach berry Devil’s fig. See turkey berry Devils-grass. See Quackgrass Devil’s guts. See Field Bindweed Devil’s hair. See Japanese Dodder Devil’s tail tear-thumb. See Mile-A-Minute Diatraea succharalis, biological control (plants) giant reed, 466 Dicamba, chemical control (plants) Australian pine, 543 gorse, 511 Japanese honeysuckle, 617 multiflora rose, 525 musk thistle, 403 prickly Russian thistle, 413 spotted knapweed, 421 strawberry guava, 578

tamarisk, 585 tropical soda apple, 534 Didemnid. See Colonial Tunicate Didemnum vexillum. See Colonial Tunicate Diffuse knapweed, 419, 650 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 690 Digging out, hand pulling, or bulldozing, physical control (plants) Asiatic colubrina, 495 buffelgrass, 438 cordgrasses, 457 dyer’s woad, 364 giant hogweed, 375 ice plant, 386 Japanese barberry, 514 Japanese hops, 621 Japanese stilt grass, 468 Kahili ginger, 394 mile-a-minute, 628 porcelainberry, 635 tamarisk, 584 velvet tree, 592 Diorhabda elongate. See saltcedar leaf beetle Dioscorea species, 607, 660 Diplodia natalensis, biological control (plants) Australian pine, 543 Diquat, chemical control (plants) giant salvinia, 329 Dittander. See Perennial Pepperweed Dodder, 386. See also Japanese Dodder Dog grass. See Quackgrass Dog rose, 523–24, 657 Dog-strangling vine. See Pale Swallow-Wort Dolichos hirsutus. See Kudzu Dolichos lobatus. See Kudzu Dollar leaf plant. See prostrate tickrefoil Domesticated livestock, xviii (v. 1), xxiv (v. 1) Dorosoma cepedianum. See Gizzard Shad Downy brome. See Cheatgrass Downy chess. See Cheatgrass Drake, J. A., xxxi (v. 1) Dreissena polymorpha. See Zebra Mussel Dreissena rostriformis bugensis. See Quagga mussel Drooping brome. See Cheatgrass Drummond rattlebox, 528–29, 657 Dutch Elm Disease Fungi, xix (v. 1), xxvi (v. 1), 21–25, 115, 130 state-by-state occurrences, 295–310 Dutchman’s pipe, 603, 660 Dwarf euonymus. See Winter Creeper Dwarf gorse, 509, 657 Dwarf honeysuckle. See European fly honeysuckle

I-12 n INDEX Dwarf St. Johnswort, 359, 650 Dyer’s Woad, 362–66 impacts, 678, 680, 682 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 690 pathways of introduction, 675, 677 uses of, 365 EAB. See Emerald Ash Borer Early chess. See Cheatgrass Early saxifrage, 370, 650 Eastern mosquito fish. See Mosquitofish Ebola, xix (v. 1) Ecological impacts, xxvi–xxvii (v. 1) in natural and semi-natural ecosystems, xxvii–xxix (v. 1). See also species entries Ecology of Biological Invasions of North American and Hawaii (Mooney and Drake), xxxi (v. 1) “Ecology of Biological Invasions” (ICSU), xxxi (v. 1) Ecology of Invasions by Animals and Plants, The (Elton), xxx (v. 1) Economic impacts, xxix–xxxi (v. 1). See also species entries Edible Periwinkle. See Common Periwinkle Eleutherodactylus coqui. See Coqui Eleutherodactylus planirostris. See Greenhouse frog Eggleaf spurge, 396, 650 Eggs and bacon. See Yellow Toadflax Eichhornia crassipes. See Waterhyacinth Eichhornia speciosa. See Waterhyacinth Elaeagnaceae. See oleaster family Elaeagnus augustifolia. See Russian Olive Elaeagnus hortensis. See Russian Olive Elaeagnus iliensis. See Russian Olive Elaeagnus umbellate. See autumn olive Elaeodendron fortunei. See Winter Creeper Eleocharus dulcis, 335 Elephant grass, 459, 460, 654 noxious designation, 691 Elm yellows, 22 Elongate paulownia, 566, 568, 659 Elton, Charles S., xx (v. 1) Elymus caput-medusae. See Medusahead Elymus repens. See Quackgrass Elytrigia repens. See Quackgrass Elytrigia vaillantiana. See Quackgrass Emerald Ash Borer, xxvit (v. 1), xxix (v. 1), 127–31 state-by-state occurrences, 299–302, 305, 309, 310

Emerging infectious diseases, xix (v. 1) Empoasca biguttula, Japanese honeysuckle as host, 617 Empress tree. See Princess Tree Enchanted Lake (O’ahu), giant salvinia, 329 Endothall, chemical control (plants) hydrilla, 334 “English House Sparrow Has Arrived in Death Valley, The An Experiment in Nature” (Grinnell), xxxi (v. 1) English ivy, 602–6 impacts, 684, 685 noxious designation, 670, 671, 693 pathways of introduction, 673, 681 and winter creeper, 641 English Sparrow. See House Sparrow Epigeic worms, 51 Epirrhoe sepergressa, biological control (plants) Japanese hops, 621 Episimus utilis, biological control (plants) Brazilian peppertree, 548 Equus asinus. See Feral Burro Equus caballus. See Feral Horse Eriocheir japonicus. See Japanese mitten crab Eriocheir sinensis. See Chinese Mitten Crab Erophora cardui, biological control (plants) Canada thistle control, 348 Erysiphe cichoracearum, biological control (plants) common mullein, 357 Erysium alliaria. See Garlic Mustard Eteobalea species, biological control (plants) toadflax, 426 Eucerocoris suspectus, biological control (plants) melaleuca, 561 Eucalyptus family, 557 Eucerocoris suspectus. See leaf-blotching bug Euhrychiopsis lecontei, biological control (plants) Eurasian watermilfoil, 324–25 Eulalia. See Japanese Stilt Grass Eulalia viminea. See Japanese Stilt Grass Eunectes murinus, 220 Eunectes notaeus, 220 Euonymus. See Winter Creeper Euonymus fortunei. See Winter Creeper Euonymus species. See Winter Creeper Euphorbiaceae. See spurge family Euphorbia esula. See Leafy Spurge Euphorbia virgata. See Leafy Spurge Eurasian Collared-Dove, 234–37 state-by-state occurrences, 295, 296, 297–300, 302–8

INDEX n I-13 Eurasian Watermilfoil, 173, 321–26, 334, 336 grass carp, 173, 325 impacts, 680, 681, 682, 685 noxious designation, 665, 666, 667, 668, 669, 670, 671, 689 pathways of introduction, 677 Eurasian wild boar. See Feral Pig European bindweed. See Field Bindweed European Earthworms, 48–53 state-by-state occurrences, 296–310 European fly honeysuckle, 504–5, 614, 657 European green crab. See Green Crab European gypsy moth. See Gypsy Moth European honey bee, xix (vol 1), 99, 102, 103, 105, 106, 107, 108, 109 European rose chalicid, biological control (plants) multiflora rose control, 526 European shore crab. See Green Crab European Starling, xviii (v. 1), xxiiit (v. 1), xxx (v. 1), 237–40 ISSG 100 worst invaders, 240, 712 and oriental bittersweet, 631 state-by-state occurrences, 295–310 European swallow-wort. See Pale Swallow-Wort European Tree Sparrow, 244 European wand loosestrife, 414, 657 European water chestnut. See Water Chestnut European wild boar. See Feral Pig Eustenopus villosus, biological control (plants) yellow starthistle, 431 Evecliptopera decurrens, biological control (plants) chocolate vine, 596 Everglades threats from invasive species, xvi (v. 1), 162, 197, 199, 218, 219, 220, 223, 490 Australian pine, 541, 542–43 Brazilian peppertree, 545, 546 climbing ferns, 599, 600 melaleuca, 558, 559, 560 West Indian marsh grass, 490 Everglade Snail Kite, 661 and waterhyacinth, 342, and West Indian marshgrass, 491 Everglades National Park, threats from invasive species, xvi (v. 1), xviii (v. 1) Asian swamp eel, 162 Burmese python, 218, 219, 220–21 green iguana 223 spotted tilapia, 197 walking catfish, 199 Executive Order 13112 (February 3, 1999), xiii (v. 1), xv (v. 1), 703

Exotic Bush Honeysuckles, 121, 502–8 impacts, 681, 683 and Japanese honeysuckle, 614 noxious designation, 666, 668, 669, 671, 692 pathways of introduction, 673, 674, 675, 676 Fabaceae. See pea family Fallopia japonica. See Japanese Knotweed False peacock fly, biological control (plants) yellow starthistle, 431 False poinciana. See Rattlebox Faya bush. See Fire Tree Fayatree. See Fire Tree Feathertop, 460, 654 Feathery pennisetum. See missiongrass Federal Noxious Weed Act, xv (v. 1), 701 Felis silvestris catus. See Feral Cat Feral Burro, 262–65 state-by-state occurrences, 295, 296, 303, 306–8 Feral Cat, xxivt (v. 1), xxxv (v. 1), 265–68 ISSG 100 worst invaders, 268, 712 state-by-state occurrences, 295–310 Feral Goat, xviii (v. 1), xxiiit (v. 1), 268–71 ISSG 100 worst invaders, 712 state-by-state occurrences, 296, 298 Feral hog/swine, 275 and tropical soda apple, 533 Feral Horse, xxiiit (v. 1), 271–75 state-by-state occurrences, 295, 296, 298, 303–10 Feral Pig, xviii (v. 1), xxiiit (v. 1), 275–81 fire tree, 556 ISSG 100 worst invaders, 280, 712 state-by-state occurrences, 295, 296, 297–300, 302, 303, 305, 306, 307, 308, 309, 310 and strawberry guava, 578 Feral pigeon. See Rock Pigeon Fergusonina species, biological control (plants) melaleuca, 561 Ficaria ranunculoides. See Fig Buttercup Ficaria verna. See Fig Buttercup Field Bindweed, 606–10 impacts, 678, 679, 684, 685 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 693 pathways of introduction, 673, 675 Field morning glory. See Field Bindweed Field thistle. See Canada thistle Fig Buttercup, 366–68 impacts, 682

I-14 n INDEX noxious designation, 668, 690 pathways of introduction, 673 Figwort family, 421, 422, 565, 719 Fire, physical control (plants). See burning Firebush. See Fire Tree Fire hazard brooms, 500 climbing ferns, 600 cogongrass, 446 common reed, 450 crimson fountain grass, 462 giant reed, 465 gorse, 511 Johnsongrass, 472 jubata grass, 477 kikuyugrass, 480 lantana, 521 medusahead, 484 melaleuca, 560 prickly Russian thistle, 412 Russian olive, 572 Firetree. See Fire Tree Fire Tree, 248, 554–57 ISSG 100 worst invaders, 710 noxious designation, 666, 667, 693 pathways of introduction, 673, 676, Fireweed, 414, 651 Fish, 157–201 American species invasive abroad, 697 ISSG 100 worst invaders, 711 Fishhook water flea, 97, 711 Five-leaf akebia. See Chocolate Vine Five-stamen tamarisk, 579, 580, 581. See also Tamarisk Flannel leaf. See Common Mullein Flannel mullein. See Common Mullein Flaxweed. See Yellow Toadflax Flies, biological control (plants) Brazilian peppertree, 548 Canada thistle, 348 climbing ferns, 601 common reed, 451 hydrilla, 334 lantana, 521 melaleuca, 561 mile-a-minute, 629 musk thistle, 403 Russian knapweed, 421 strawberry guava, 578 velvet tree, 592 waterhyacinth, 342 yellow Himalayan raspberry, 539 yellow starthistle, 431

Floating fern. See Giant Salvinia Floating fern family, 326 Floating waterhyacinth. See Waterhyacinth Florida apple snail, 68 Florida elodea. See Hydrilla Florida holly. See Brazilian Peppertree Florida Keys National Marine Sanctuary, 178 Florida thatch palm, 659 and Asiatic colubrina, 495 Flowered sage. See Lantana Fluazifop, chemical control (plants) cogongrass, 447 jubata grass, 477 pampas grass, 477 quackgrass, 488 Fluridone, chemical control (plants) Eurasian watermilfoil, 324 giant salvinia, 329 hydrilla, 334 Fluroxypry, chemical control (plants) lantana, 521 Flying carp. See Silver Carp Forbs, 344–431 American species invasive abroad, 695 ISSG 100 worst invaders, 710–11 noxious designation, 690–91 Formosan Subterranean Termite, xix (v. 1), xxiv (v. 1), xxvt (v. 1), 131–34 ISSG 100 worst invaders, 134, 711 state-by-state occurrences, 295–98, 300, 302, 305, 307, 308 Fosamine, chemical control (plants) multiflora rose, 525 Fountain grass, impacts, 679, 683 noxious designations, 667, 691. See also Crimson Fountain Grass Fragrant honeysuckle. See winter honeysuckle French broom, 496, 498, 499 noxious designation, 666, 667, 670, 692. See also Brooms French tamarisk, 579, 580, 582. See also Tamarisk Freshwater herring, 157 Fringecup, 370, 651 Frog’s-bit family, 331 FST. See Formosan Subterranean Termite Fuitour’s-grass. See Leafy Spurge Fund for Animals, animal welfare group, 271 Fungi, 11–35 American species invasive abroad, 697 Fungi, biological control (plants) Asiatic sand sedge, 439 Australian pine, 543 buffelgrass, 439

INDEX n I-15 Canada thistle, 349 cheatgrass, 443 chocolate vine, 596 cogongrass, 447 common mullein, 357 common reed, 447 cordgrasses, 458 dyer’s woad, 365 Eurasian watermilfoil, 325 fire tree, 557 Japanese hops, 621 kikuyugrass, 481 Koster’s curse, 518 kudzu, 625 paper mulberry, 564 silk tree, 575 tree of heaven, 589 tropical soda apple, 533 velvet tree, 592 waterhyacinth, 342–43 West Indian marshgrass, 492 winter creeper, 643–44 yellow starthistle, 431 Furze. See Gorse Fusarium nivale, biological control (plants) cheatgrass, 443 Fusarium oxysporum, biological control (plants) tree of heaven, 589 Fusarium oxysporum f. perniciosum. See mimosa wilt Galarhoeus esula, biological control (plants). See Leafy Spurge Galerucella species, biological control (plants) purple loosestrife, 417 water chestnut, 338 Gallerucida bifasciata, biological control (plants) Japanese knotweed, 390 Gallina de palo, 221 Gambusia affinis. See Mosquitofish Gambusia holbrooki. See Mosquitofish Garlic Mustard, 51, 369–72, 507 impacts, 682 noxious designation, 665, 666, 668, 669, 670, 671, 690 pathways of introduction, 675, 676 Gateway National Recreation Area, 435 Genista junceum. See Brooms Genista monspessulana. See French Broom Geomyces destructans. See Bat White-Nose Syndrome Fungus Georgia bully, 600, 657 Geraldton carnation weed, 396, 651 German trout. See Brown Trout

Giant African land snail. See Giant African Snail Giant African Snail, 64–67 state-by-state occurrences, 298 Giant air plant, 600, 651 Giant Asian dodder. See Japanese Dodder Giant cow-parsnip. See Giant Hogweed Giant Hogweed, 372–76 impacts, 678, 681, 682 noxious designation, 665, 666, 668, 669, 670, 671, 690 pathways of introduction, 673, 676 Giant knotweed, 388, 651, noxious designation, 666, 670, 671, 690 Giant Reed, 449, 462–66 impacts, 679, 681, 683, 686 ISSG 100 worst invaders, 710 noxious designation, 671, 691 pathways of introduction, 673, 675 uses of, 465. See also Common Reed Giant reedgrass. See Common Reed Giant Salvinia, 326–30 impacts, 681, 682, 685 noxious designation, 665, 666, 668, 669, 670, 671 pathways of introduction, 674, 677 Giant tree frog. See Cuban Treefrog Giant whiteweed. See Perennial Pepperweed Giant wild pine, 600, 651 Gill-over-the-ground. See ground ivy Ginger family, 391 Ginger-lily. See white ginger Ginseng family, 602 Gizzard Shad, 164, 165, 168–71 state-by-state occurrences, 295, 296, 299, 300, 302, 303, 306, 308, 310 Glacier National Park, and white pine blister rust, 34 Glassy-Winged Sharpshooter, xxvit (v. 1), 134–38 state-by-state occurrences, 296 Globe artichoke, 651 and Canada thistle, 348 Gloger’s Rule, xxxi (v. 1) Glorybush, 515, 590, 657 and Koster’s curse, 515 Glut herring. See Alewife Glyphosate, chemical control (plants) Asiatic sand sedge, 435 Australian pine, 543 Brazilian peppertree, 547 brooms, 501 buffelgrass, 439 Canada thistle, 348 carrotwood, 550

I-16 n INDEX cheatgrass, 443 chinaberry, 554 Chinese lespedeza, 352 chocolate vine, 596 climbing ferns, 601 cogongrass, 446 common mullein, 356 common reed, 451 English ivy, 605 exotic bush honeysuckles, 506 field bindweed, 609 fig buttercup, 368 fire tree, 557 garlic mustard, 371 giant hogweed, 375 giant reed, 465 giant salvinia, 329 gorse, 511 goutweed, 379 halogeton, 382 ice plant, 386 Japanese barberry, 514 Japanese honeysuckle, 617 Japanese hops, 621 Japanese knotweed, 390 Japanese stiltgrass, 469 Johnsongrass, 472 jubata grass, 477 kikuyugrass, 481 Koster’s curse, 518 kudzu, 625 lantana, 521 leafy spurge, 398 medusahead, 484 melaleuca, 561 mile-a-minute, 628 multiflora rose, 525 musk thistle, 403 Oriental bittersweet, 632 pampas grass, 477 papermulberry, 564 perennial pepperweed, 409 porcelainberry, 635 prickly Russian thistle, 413 princess tree, 568 purple loosestrife, 417 quackgrass, 488 rattlebox, 529 silk tree, 575 swallow-worts, 640 tamarisk, 584 toadflax, 426 tree of heaven, 588 tropical soda apple, 534

waterhyacinth, 342 West Indian marsh grass, 492 winter creeper, 643 wisteria, 647 yellow Himalayan raspberry, 538 Glysine sinensis. See Chinese Wisteria Goats and brooms, 501 and fire tree, 557 and gorse, 511 plants toxic to, 360 Gold clam. See Asian clam Golden Apple Snail, xxiiit (v. 1), 67–70 ISSG 100 worst invaders, 69, 711 state-by-state occurrences, 296, 297, 298, 308 Golden shad. See Alewife Golden starthistle. See Yellow Starthistle Golden star tunicate, 40 Golpar, 374 Gooseberries, White Pine Blister Rust alternate host, 30, 32, 34 Goosefoot family, 379, 409 Gopher plant. See caper spurge Gopher tortoise, 228, 663 and Australian pine, 543 and cogon grass, 446 Gorse, 508–12 and brooms, 498 impacts, 680, 683 ISSG 100 worst invaders, 710 noxious designation, 666, 667, 670, 671, 692 pathways of introduction, 673, 675 Goutweed, 376–79 impacts, 682 noxious designation, 666, 668, 671, 690 pathways of introduction, 673 Gracula religiosa, 233 Graminoids, 432–92 American species invasive abroad, 696 herbicides, xx (v. 2) ISSG 100 worst invaders, 710 noxious designation, 691–92 Grape family, 633 Grape honeysuckle, 505, 657 Grape industry threat, Glassy-Winged Sharpshooter, 137 Grass Carp, 164, 172–75 Hydrilla control, 334 state-by-state occurrences, 296, 300, 302, 307, 308 Grass Carp, biological control (plants) Eurasian watermilfoil, 325 hydrilla, 334 waterhyacinth, 342

INDEX n I-17 Grass family, 435, 439, 443, 447, 452, 458, 462, 466, 469, 473, 478, 481, 485, 489 Grasshoppers, biological control (plants) cheatgrass, 443 Chinese lespedeza, 353 Gratiana boliviana, biological control (plants) tropical soda apple, 534 Gray, Asa water chestnut cultivation, 336 Gray herring. See Alewife Gray thistle. See wavyleaf thistle Grazing, physical control (plants) brooms, 501 giant hogweed, 375 kudzu, 625 medusahead, 484 spotted knapweed, 420 tree of heaven, 588 yellow starthistle, 430 Greater celandine. See celandine Great Lakes, xxiv (v. 1), xxvii (v. 1), xxix (v. 1), xxx (v. 1) alewives, 157, 158, 159 Eurasian watermilfoil, 325 gizzard shad, 169 impacts of sea lamprey, 193 musk thistle, 402 New Zealand mud snail, 73, 74 quagga mussel, 76, 77, 78 round goby, 187, 189, 190, 193 sea lamprey, 191 spiny water flea, 96, 97 threat from bighead carp, 165, 166 tubenose goby, 188 water chestnut, 335, 336, 337 zebra mussel, 82, 83, 86 Great shipworm. See Naval Shipworm Great Smoky Mountains National Park, and hemlock woolly adelgid, 143, 145 and feral pigs, 279 Green anaconda, 220 Green comet milkweed, and white swallow-wort, 637, 651 Green Crab, xxxi (v. 1), 90–92 state-by-state occurrences, 296, 297, 300, 301, 304, 305, 306, 307, 309 Greenheart. See coffee colubrina Greenhouse frog, 208–9 Green Iguana, 221–25 state-by-state occurrences, 297, 298, 308, 310 Green-lipped mussel. See Asian Green Mussel Green mussel. See Asian Green Mussel

Green peach aphid, 663 and tropical soda apple as host, 533–34 Green sea turtle, 286, 543, 663 Grey worms. See European Earthworms Grinnell, Joseph, xxxi (v. 1) Ground elder. See Goutweed Ground ivy, 367, 651 Gully-bean. See turkey berry GWSS. See Glassy-winged Sharpshooter Gypsy Moth, xix (v. 1), xxivt (v. 1), xxvt (v. 1), 138–42 ISSG 100 worst invaders, 711 state-by-state occurrences, 295–97, 299, 300, 301, 303, 304, 305, 307–10 Gymnancyla canela, biological control (plants) prickly Russian thistle, 413 Gymnaetron tetrum, biological control (plants) common mullein, 357 Gynerium argentium. See Pampas Grass Gynerium jubatum. See Jubata Grass Hack-and-squirt, herbicide application, xx (v. 2) Haghighat, Sahar, exotic bush honeysuckle study, 507 Hairy lespedeza. See Chinese Lespedeza Hairy wheatgrass, 487, 654 Hairy whitetop, 406, 651 noxious designation, 665, 666, 667, 670, 671, 672, 690 Haleakala National Park, and Argentine ants, 110, 112 Halogeton, 379–83 impacts, 678, 680, 682 noxious designation, 665, 666, 667, 669, 670, 690 pathways of introduction, 677 and Russian thistle, 412 Halogeton glomeratus. See Halogeton Haloragaceae. See watermilfoil family Halloween lady beetle. See Multicolored Asian Lady Beetle Hall’s honeysuckle, 614, 660 Halyomorpha halys. See Brown Marmorated Stink Bug Harmonia axyridis. See Multicolored Asian Lady Beetle Harold L. Lyon Arboretum, velvet tree, 590 Harris mud crab, 87 Hart’s tongue fern, 639, 651 Hawaiian blackberry, 536, 657 Hawai’i Volcanoes National Park and feral goats, 270 and fire tree, 555, 556

I-18 n INDEX and kahili ginger, 392, 393, 394 and yellow Himalayan raspberry, 538 Hawkmoth, biological control (plants) leafy spurge, 398 Heartleaf horsenettle, 532, 651 Heart-podded hoary cress. See Hoary Cress Hedera helix. See English Ivy Hedge false bindweed, 607, 660 Hedge garlic. See Garlic Mustard Hedychium gardnerianum. See Kahili Ginger Hemlock Woolly Adelgid, xix (v. 1), xxvit (v. 1), 142–45 state-by-state occurrences, 297, 298, 300, 301, 307–9 Hemp family, 618 Hemp sesbania, 528 noxious designation, 665, 690, 692 Herbicide control. See species entries Herbicides application methods, xx (v. 2) major categories, xx (v. 2) Heracleum mantegazzianum. See Giant Hogweed Heracleum species. See Giant Hogweed Herpestes javanicus. See Indian Mongoose Herpetogramma licarsicalis, biological control (plants) kikuyugrass, 481 Heteranthera formosa. See Waterhyacinth Heterodera sinensis, biological control (plants) cogongrass, 447 Heteroperreyia hubrichi, biological control (plants) Brazilian peppertree, 548 Hexazinone, chemical control (plants) Brazilian peppertree, 547 buffelgrass, 439 crimson fountain grass, 462 giant salvinia, 329 Highway ice plant. See Ice Plant Hildebrand, Dr. William, 233 Hill Myna, 233 Himalayan blackberry, 537, 657 noxious designation, 670, 692 pathways of introduction, 676 Himalayan bush clover. See Chinese Lespedeza Histoplasma capsulatum, Rock Pigeon as host, 258 HIV, xix (v. 1) Hive death, honeybee tracheal mite as cause, 99, 100 Hoary Cress, 404–9 pathways of introduction, 677 “Hogzilla,” Georgia wild pig, 277 Hoh River, Japanese knotweed, 389

Hojo-e, Buddhist captive animal release ceremony, 165 Holcus halapensis. See Johnsongrass Hollyhock bindweed. See mallow bindweed “Hollywood Finches,” 241 Homalodisca vitripennis. See Glassy-Winged Sharpshooter Homogenization, of biota, xxviii–xix (v. 1) Honey bee, 663 and gorse, 511. See also Asian honey bee Honeybee Tracheal Mite, xix (v. 1), 99–102 state-by-state occurrences, 295–310 Honeycreepers, Hawaii, xxvii (v. 1), 1–3, 217, 247, 261 Honeylocust, 574, 659 Honeysuckle family, 502, 614 Honeysuckle. See Exotic Bush Honeysuckles; Japanese Honeysuckle Honeyvine, 637, 660 Hordeum caput-medusae. See Medusahead Horn nut. See devil pod Horned water chestnut. See Water Chestnut Horses, plants toxic to buffelgrass, 438 common St. Johnswort, 360 field bindweed, 609 Johnsongrass, 472 rattlebox, 529 yellow starthistle, 430 Horsetail tree. See Australian Pine Hottentot fig. See Ice Plant House cat. See Feral Cat House Finch, xiii (v. 1), 240–43 state-by-state occurrences, 295–310 House Mouse, 281–83 ISSG 100 worst invaders, 712 state-by-state occurrences, 295–10 House Myna. See Common Myna House rat. See Black Rat House Sparrow, xviii (v. 1), xxiiit (v. 1), xxxi (v. 1), 1, 238, 241, 243–46 state-by-state occurrences, 295–310 Human factor in species invasions, xxxii (v. 1) Humboldt Bay, smooth cordgrass eradication, 458 Humboldt Bay owl’s clover, 457, 651 Humulus japonicus. See Japanese Hops Humulus scandens. See Japanese Hops Hyadaphis tatariacae, biological control (plants) exotic bush honeysuckles, 507 Hybridization, impacts, xxviii (v. 1) Hydrellia species, biological control (plants) hydrilla, 334

INDEX n I-19 Hydrilla, xviii (v. 1), xxx (v. 1), 173, 331–35, 336 impacts, 681, 682, 685 noxious designation, 665, 66, 667, 668, 669, 670, 671, 689 pathways of introduction, 674, 677 Hydrilla verticillata. See Hydrilla Hydrocharitaceae. See frog’s-bit family Hyles euphorbiae. See hawkmoth Hylobius transversovittatus, biological control (plants) purple loosestrife, 417 Hymenachne acutigluma. See West Indian Marsh Grass Hymenachne amplexicaulis. See West Indian Marsh Grass Hypena srigata, biological control (plants) lantana, 521 Hypericum perforatum. See Common St. Johnswort Hyperparathyroidism disease, in horses, 438 Hypophthalmichthys molitrix. See Silver Carp Hypophthalmichthys nobilis. See Bighead Carp ‘Inia. See Chinaberry Iberian knapweed, 419, 651 noxious designation, 665, 666, 669, 670, 690 Iberian starthistle, 428, 651 Ice Plant, 383–87 impacts, 683 noxious designation, 690 pathways of introduction, 675 Ice plant scale insects, biological control (plants) ice plant, 386 Iguana iguana. See Green Iguana Imazapic, chemical control (plants) cheatgrass, 443 dyer’s woad, 365 Japanese stilt grass, 469 Imazapyr, chemical control (plants) Brazilian peppertree, 547 chinaberry, 554 climbing ferns, 601 cogongrass, 446 common reed, 447 cordgrasses, 457 exotic bush honeysuckles, 506 hoary cress, 409 jubata grass, 477 kahili ginger, 394 lantana, 521 mile-a-minute, 628 melaleuca, 561

pampas grass, 477 perennial pepperweed, 409 silk tree, 575 tamarisk, 584 tropical soda apple, 534 west Indian marshgrass, 492 yellow Himalayan raspberry, 539 Imperata arundinaceae. See Cogongrass Imperata cylindrica. See Cogongrass Imperata cylindrica var. major. See Cogongrass Indian lilac. See Chinaberry Indian Mongoose, xviii (v. 1), xxiiit (v. 1), xxvi (v. 1), 284–86 ISSG 100 worst invaders, 285, 712 state-by-state occurrences, 298, 310 Indian Myna. See Common Myna Indian snakewood. See Asiatic Colubrina Indian star vine. See Hydrilla Indigo snake, 446, 663 Infectious diseases, xxiiit (v. 1) Influenza, xix (v. 1) Injurious animal species, definition, xv (v. 1) Insects, 106–56 American species invasive abroad, 696 Insects, biological control (plants), xviii (v. 2), xix (v. 2) Australian pine, 543 Brazilian peppertree, 547–48 brooms, 501–2 Canada thistle, 348–49 climbing ferns, 601 common mullein, 357 common reed, 451 common St. Johnswort, 361 Eurasian watermilfoil, 324–25 field bindweed, 609 fire tree, 557 garlic mustard, 372 giant hogweed, 375 giant reed, 466 giant salvinia, 330 gorse, 511 halogeton, 383 hoary cress, 409 hydrilla, 334 ice plant, 386 Japanese hops, 621 Japanese knotweed, 390 kikuyugrass, 481 Koster’s curse, 518 kudzu, 625 lantana, 521 leafy spurge, 398–99 mile-a-minute, 628–29

I-20 n INDEX melaleuca, 561 multi-flora rose, 526 musk thistle, 403 perennial pepperweed, 409 prickly Russian thistle, 413 purple loosestrife, 417 rattlebox, 529 spotted knapweed, 421 strawberry guava, 578–79 swallow-wort, 640 tamarisk, 585 toadflax, 426 tropical soda apple, 534 waterhyacinth, 342–43 west Indian marsh grass, 492 yellow starthistle, 43–31. See also flies, beetles, butterflies, midges, mites, wasps, and weevils Intentional pathways of introduction, xxiiit–xxivt (v. 1) Intermediate wheatgrass, 484, 654 International Biosphere Reserve, Everglades, 560 International Maritime Organization, 708 International Plant Protection Convention (IPPC), 700, 707 Introduced species, xiv (v. 1) Invasion process, xx–xxii (v. 1) Invasion science, xxx–xxxi (v. 1) Invasive plants American species abroad, 695–96 impacts of, xviii (v. 2), 678–86 introduction of, xvii–xviii (v. 2), 673–77 management, xix (v. 2) noxious designation, 665–71, 689–93 organizations and publications concerning, 687–88 problem of, xviii (v. 2) reproduction/dispersal, xvii (v. 2) Invasive species animal problem extent, xviii–xx (v. 1) definitions, xiii–xv (v. 1) ecological impacts, xxvi–xxvii (v. 1) economic impacts, xxix–xxxi (v. 1) federal legislation and agreements pertaining to, 699–706 human factor, xxxii (v. 1) international agreements and conventions pertaining to, 707–9 natural ecosystem impacts, xxvii–xxix (v. 1) pathways of introduction, xxii–xxvi (v. 1) plant problem extent, xv–xviii (v. 1) process, xx–xxii (v. 1)

public health and well-being impacts, xxx (v. 1) Invasive Species Specialist Group (ISSG)100 worst invasive alien species, 710–12 Invertebrates, 36–156 American species invasive abroad, 696–97 Annelid Worms, 48–53 Bryozoan, 36–38 Cnidarian, 45–48 ISSG 100 worst invaders, 711 Mollusks, 53–86 Tunicates, 39–45 Ioxodes scapularis. See Black-legged tick Ipomoea species. See pipevine and Dutchman’s pipe Irish furze. See Gorse Irish ivy. See Atlantic ivy Ironwood. See Australian Pine Isatis tinctoria. See Dyer’s Woad Ischnodemus variegatus. See myakka bug Island applesnail, 67 Italian thistle, 346, 401, 651 noxious designation, 665, 666, 667, 670, 671, 690 Jack-by-the-hedge. See Garlic Mustard Jacob’s ladder. See Yellow Toadflax Jacob’s staff. See Common Mullein Jamaican giant anole, 223 Japanese arrowroot. See Kudzu Japanese bamboo. See Japanese Knotweed Japanese barberry, 51, 512–15 impacts, 683 noxious designation, 666, 668, 692 pathways of introduction, 673, 674 Japanese Beetle, xxvit (v. 1), 146–48 state-by-state occurrences, 295–310 Japanese blood grass. See Cogongrass Japanese brome, 440, 654, 692 Japanese Climbing Fern, 597–602 noxious designation, 665, 667, 693 pathways of introduction, 673 Japanese creeper. See Boston ivy Japanese Dodder, 610–14 in medicine, 613 impacts, 678, 684, 685 noxious designation, 665, 666, 667, 668, 669, 670, 671 Japanese fleece flower. See Japanese Knotweed Japanese Honeysuckle, 614–18, 641–42 impacts, 684, 685 noxious designation, 666, 668, 669, 671, 693 pathways of introduction, 673 Japanese hop. See Japanese Hops

INDEX n I-21 Japanese Hops, 618–21 impacts, 681, 684 noxious designation, 666, 668, 693 pathways of introduction, 673, 675 Japanese Knotweed, 387–91 impacts, 681, 682, 685 ISSG 100 worst invaders, 710 noxious designation, 665, 666, 668, 669, 670, 671, 690 pathways of introduction, 673, 675 uses of, 390 Japanese lady beetle. See Multicolored Asian lady beetle Japanese millet, biological control (plants) purple loosestrife, 417 Japanese mitten crab, 87 Japanese mystery snail. See Chinese Mystery Snail Japanese oyster, 40 Japanese sedge. See Asiatic Sand Sedge Japanese Silver-eye, 556 Japanese Stilt Grass, 466–69 impacts, 683 noxious designation, 665, 666, 668, 691 pathways of introduction, 676 Japanese White-Eye, xviii (v. 1), 246–48 and kahili ginger, 393 state-by-state occurrence, 298 and strawberry guava, 578 and velvet tree, 591 Japanese wisteria. See Wisteria Jenkin’s spire shell. See New Zealand Mud Snail Jesup’s milkvetch, 651 and swallow-worts, 639 Johnson, Velma B. (“Wild Horse Annie”), 273 Johnson grass. See Johnsongrass Johnsongrass, 469–72 impacts, 678, 679, 680, 681, 683, 685 noxious designation, 667, 668, 670 pathways of introduction, 675 Jointed grass, 467, 654 Jubata Grass, 472–77 impacts, 679, 683, 685 noxious designation, 667, 691 pathways of introduction, 673 Kahila garland lily. See Kahili Ginger Kahili. See Kahili Ginger Kahili Ginger, 391–94 impacts, 681, 682 ISSG 100 worst invaders, 710

noxious designation, 690 pathways of introduction, 673 Kariba weed. See Giant Salvinia Karritree. See Princess Tree Kelp destruction, Lacy Crust Bryozoan, 37 Kerr, Dr. Warwick, 106 Key West quail-dove, 285 Kiger mustang, 272 Kikuyugrass, 462, 478–81 impacts, 678, 679, 680 noxious designation, 665, 666, 668, 669, 670, 671, 690 pathways of introduction, 675 Killer bee. See Africanized Honey Bee King, Helen Dean, 289 Klamath weed. See Common St. Johnswort Knight anole, 223 Knobbed whelk, 80 Koa tree, 659 and fire tree, 556 and strawberry guava, 577 and velvet tree, 590 Kochia. See burning bush Koi kandy. See Giant Salvinia Koster’s Curse, 209, 515–18, 589 impacts, 683 ISSG 100 worst invaders, 710 noxious designation, 667, 692 pathways of introduction, 673, 674, 677 and velvet tree, 589 Kraunhia floribunda. See Japanese Wisteria Kraunhia floribunda var. alba. See Japanese Wisteria Kraunhia floribunda var. sinensis. See Chinese Wisteria Kraunhia japonica. See Japanese Wisteria Kraunhia sinensis. See Chinese Wisteria Kudzu, 622–26 impacts, 684 ISSG 100 worst invaders, 710 and Japanese dodder, 611, 612 noxious designation, 666, 667, 668, 670, 671, 693 pathways of introduction, 674, 675 uses of, 624, 625 Kyack. See Alewife Kyasuma grass, 459, 461, 654 noxious designation, 665, 666, 668, 669, 670, 671, 691 Lace bug, biological control (plants) Canada thistle, 349 lantana, 521 Lacey Act, xvi (v. 1), 196, 200, 319, 699, 704

I-22 n INDEX Lacy Crust Bryozoan, xv (v. 1), xxiv (v. 1), 36–38 state-by-state occurrences, 297, 300, 301, 303, 306 Lagurus cylindricus. See Cogongrass Lake lamprey. See Sea Lamprey Lamprey eel. See Sea Lamprey Land invertebrate, ISSG 100 worst invaders, 711 Lantana, 234, 248, 518–22 impacts, 678, 679, 680, 681, 683, 685 ISSG 100 worst invaders, 710 noxious designation, 692 pathways of introduction, 674 uses of, 522 Lantana aculeate. See Lantana Lantana camara. See Lantana Lantana camara var. aculeata. See Lantana Lantana camara var. nivea. See Lantana Lantana wildtype. See Lantana Lardizabala family, 594 Lardizabalaceae. See lardizabala family Large St. Johnswort, 358, 651 Large-headed sedge, 432, 654 Largeleaf lantana. See Lantana Larinus curtus, biological control (plants) yellow starthistle, 431 Larinus minutus, biological control (plants) spotted knapweed, 421 Larinus planus, biological control (plants) Canada thistle control, 348 Latherleaf. See Asiatic Colubrina Laycock, George, xxxi (v. 1) Leaf-blotching bug, biological control (plants) melaleuca, 561 Leaf rust, biological control (plants) pepperweed, 409 Leaf worms. See European Earthworms Leafy Spurge, 395–99 impacts, 678, 680, 681, 682 ISSG 100 invasive worst, 710 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 690 pathways of introduction, 677 Least Bell’s Vireo, 662 and giant reeds, 464 and Japanese dodder, 612 Least Tern, 255, 662 and Asiatic sand sedge, 434 Legless red mealybug, biological control (plants) common reed, 451 Legume family, 527. See also pea family Leiopython albertisii, 220 Lens-pod hoary cress, 405, 651 noxious designation, 690

Lepidium draba. See Hoary Cress Lepidium latifolium. See Perennial Pepperweed Leptinotarsa texana, biological control (plants) tropical soda apple, 534 Leptospirosis, Norway Rat as host, 290 Lespedeza cuneata. See Chinese Lespedeza Lespedeza juncea var. sericea. See Chinese Lespedeza Lespedeza sericea. See Chinese Lespedeza Lespedeza webworm, Chinese lespedeza control, 353 Lesser celadine. See Fig Buttercup Leucantha solstitialis. See Yellow Starthistle Leucoptera spartifolilella, biological control (plants) brooms, 501 Linaria dalmatica ssp. dalmatica. See Dalmatian Toadflax Linaria genistifolia ssp. dalmatica. See Dalmatian Toadflax Linaria vulgaris. See Yellow Toadflax Linepithema humile. See Argentine Ant Linnet. See House Finch Lionfish, xxiiit (v. 1), 175–78 state-by-state occurrences, 297, 298, 305, 307 Liothrips urichi, biological control (plants) Koster’s curse, 518 Lipara species, biological control (plants) common reed, 451 Lithobates catesbeianus. See American Bullfrog Lithracus atronotatus, biological control (plants) Brazilian peppertree, 548 Little, Clarence Cook, 282 Littleleaf sensitive briar, 574, 660 Littoraria irrorata. See marsh periwinkle Littorina littorea. See Common Periwinkle Littorina saxatilis. See Rough Periwinkle Lius peisodon, biological control (plants) Koster’s curse, 518 Lumbricus rubellus. See European Earthworms Lumbricus terretris. See European Earthworms Lonicera insularis. See Exotic Bush Honeysuckles Lonicera japonica. See Japanese Honeysuckle Lonicera maackii. See Amur Honeysuckle Lonicera morrowiii. See Morrow’s Honeysuckle Lonicera sibirica. See Exotic Bush Honeysuckles Lonicera tatarica. See Tatarian honeysuckle Lonicera x bella. See Bell’s Honeysuckle Lonicera japonica. See Japanese Honeysuckle Loosestrife family, 414 Lophyrotoma zonalis, biological control (plants) melaleuca, 561 Louis’ swallow-wort. See Black Swallow-Wort

INDEX n I-23 Love-apple. See cockroach berry Lygodiaceae. See climbing fern family Lygodium japonicum. See Japanese Climbing Fern Lygodium microphyllum. See Old World Climbing Fern Lygodium scandens. See Old World Climbing Fern Lymantria dispar. See Gypsy Moth Lymantria xylina, biological control (plants) Australian pine, 543 Lyme Disease Bacterium, xix (v. 1), xxx (v. 1), 3–7 state-by-state occurrences, 296, 298, 299, 300. 301, 304, 306–10 Lythraceae. See loosestrife family Lythrum salicaria. See Purple Loosestrife MacArthur, Robert, xxxi (v. 1) Maccartney rose, 523, 657 Machineel, 495, 659 Madwoman’s milk, 396, 651 Magainins, African Clawed Frog, 204 Magur. See Walking Catfish Mahogany family, 551 Mahogany flat. See Common Bed Bug Mallow bindweed, 607, 661 Malta starthistle, 427, 651 noxious designation, 669, 690 Mammals, 259–94 American species invasive abroad, 697 ISSG 100 worst invaders, 712 Mangosteen family, 358 Mangroves, 548, 550 Marine vomit. See Colonial Tunicate Marlahan mustard. See Dyer’s Woad Marsh marigold, 367, 651 Marsh periwinkle, biological control (plants) cordgrass, 458 Mecinnus janthirus, biological control (plants) toadflax, 426 Medusae, jellyfish generation, 46, 47 Medusahead, 481–84 and cheatgrass, 442, impacts, 679, 680, 683, 691 noxious designation, 666, 670, 671 pathways of introduction, 677 Medusahead wildrye. See Medusahead Megamelus species, biological control (plants) waterhyacinth, 342 Megastigmus aculeatus var. nigroflavus, biological control (plants) multiflora rose, 526

Megastigmus transvaalensis, biological control (plants) Brazilian peppertree, 548 Me-jiro. See Japanese White-Eye Melaleuca, 557–61 impacts, 680, 681, 684 ISSG 100 worst invaders, 710 noxious designation, 665, 666, 668, 669, 670, 671, 692 pathways of introduction, 674, 675, 666 Melaleuca quinquenervia. See Melaleuca Melaleuca species. See Melaleuca Melastoma elegans. See Koster’s Curse Melastoma hirta. See Koster’s Curse Melastoma hirtum. See Koster’s Curse Melastomataceae. See melastome family Melastome family, 515, 589 Meliaceae. See mahogany family Melia species. See Chinaberry Melia azedarach. See Chinaberry Melopsitticus undulates. See Budgerigar Membranipora membranacea. See Lacy Crust Bryozoan Mesembryanthemum crystallinum. See Crystalline Ice Plant Mesembryanthemum edule. See Ice Plant Metriona elatior, biological control (plants) tropical soda apple, 534 Metrosideros quinquenervia. See Melaleuca Metsulfuron, chemical control (plants) climbing ferns, 601 common St. Johnswort, 361 dyer’s woad, 365 halogeton, 382 hoary cress, 409 Japanese hops, 621 yellow Himalayan raspberry, 539 Metzneria paucipunctella, biological control (plants) spotted knapweed, 421 Mexican bamboo. See Japanese knotweed Mexican garter snake, 207 Mexican water-fern, 327, 649 Miconia. See Velvet Tree Miconia calvescens. See Velvet Tree Miconia magnifica. See Velvet Tree Microorganisms, 1–10 ISSG 100 worst invaders, 710 Microstegium imberbe. See Japanese Stilt Grass Microstegium vimineum. See Japanese Stilt Grass Midges, biological control (plants) cogongrass, 447 common reed, 451 Eurasian watermilfoil, 324, 325 leafy spurge, 399

I-24 n INDEX Migratory Bird Treaty Act (2001), 255 Mikania micrantha, 626, 710 Mile-A-Minute, 626–29 impacts, 678, 684, 685 noxious designation, 665, 666, 669, 670, 693. See also Mikania micrantha Mile-a-minute weed. See Mile-A-Minute Milfoil midge, biological control (plants) Eurasian watermilfoil, 324 Military grass. See Cheatgrass Milk thistle, 346, 651 Milkweed family, 636 Millettia japonica. See Japanese Wisteria Mimosa. See Silk Tree Mimosa arborea. See Silk Tree Mimosa julibrissin. See Silk Tree Mimosa wilt, biological control (plants) silk tree, 575 Missiongrass, 459–60, 655 Mites, biological control (plants) climbing ferns, 601 field bindweed, 609 gorse, 511 multiflora rose, 526 prickly Russian thistle, 413 waterhyacinth, 342 Mollusks, 53–86 American species invasive abroad, 696 Mompha trithalama, biological control (plants) Koster’s curse, 518 Monarch butterflies, 663 and Asiatic sand sedge, 434 and swallow-worts, 639 Money monitor. See Nile Monitor Monk Parakeet, xxvt (v. 1), xxix (v. 1), 248–52 state-by-state occurrences, 295, 297–300, 304–8, 310 Monogynella japonica. See Japanese Dodder Monopterus albus. See Asian Swamp Eel Montana Dyer’s Woad Cooperative Project, 365 Mooney, H. A., xxxi (v. 1) Moraceae. See mulberry family Morella faya. See Fire Tree Morning glory family, 606 Morrow’s honeysuckle, noxious designation, 666, 668, 669, 671, 692 and Japanese honeysuckle, 614. See also Exotic Bush Honeysuckles Mosquito fern, 327, 329, 650 Mosquitofish, xxiiit (v. 1), 178–82 ISSG 100 worst invaders, 181, 711 state-by-state occurrences, 295–306, 307–10

Mosquitos Asian Tiger, 116–20 as avian malaria vectors, 1, 3 as tularemia vector, 290 as West Nile virus vector, 8, 9, 119 Yellow fever mosquito, 117 Moths, biological control (plants) Australian pine, 543 bindweed, 609 Brazilian peppertree, 547–48 brooms, 501 chocolate vine, 596 climbing ferns, 601 common mullein, 357 common reed, 451 common St. Johnswort, 361 Eurasian watermilfoil, 324–25 field bindweed, 609 fire tree, 557 giant reed, 466 gorse, 511 halogeton, 383 hydrilla, 334 Japanese hops, 621 Koster’s curse, 518 leafy spurge, 398 mile-a-minute, 629 prickly Russian thistle, 413 Russian knapweed, 421 sawtooth blackberry, 539 spotted knapweed, 421 toadflax, 426 velvet tree, 592 waterhyacinth, 342 Moth mullein, 354, 651 Mowing. See cutting Mud shad. See Gizzard Shad Mulberry family, 562 Mulching, tarping, or solarization, physical control (plants) chocolate vine, 596 common reed, 451 cordgrasses, 457 English ivy, 605 field bindweed, 609 goutweed, 379 Japanese knotweed, 390 Johnsongrass, 472 kikuyugrass, 481 West Indian marsh grass, 491 winter creeper, 643 Mulhaden. See Alewife Mullein moth, biological control (plants) mullein, 347

INDEX n I-25 Multicolored Asian Lady Beetle, xxiiit (v. 1), xxx (v. 1), 148–52 state-by-state occurrences, 307 Multiflora Rose, 522–26 impacts, 678, 680, 683, 685 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 692 pathways of introduction, 674, 675, 676 Musk Thistle, 345, 348, 399–404 impacts, 680, 683 noxious designation, 666, 667, 668, 669, 670, 671, 672, 690 pathways of introduction, 677 Mus musculus. See House Mouse Mustang. See Feral Horse Mustard family, 362, 369, 404 Mute Swan, 252–56 state-by-state occurrences, 297, 300, 301, 304, 305, 309 Myakka bug, biological control (plants) West Indian marsh grass, 492 Myiopsitta monachus. See Monk Parakeet Myocastor coypus. See Nutria Mycoplasmal conjunctivitis House Finch decline, 241–42 spread, 243 Mylopharyngodon piceus. See Black Carp Myrica faya. See Fire Tree Myricaceae. See sweet gale family Myriophyllum spicatum. See Eurasian Watermilfoil Myriothecium verrucaris, biological control (plants) kudzu, 625 Myrtaceae. See eucalyptus family; myrtle family Myrtle family, 557, 576 Mytella charruana. See Charru mussel Myxobolus cerebralis. See Whirling Disease Nanday Conure (parakeet), 250 Nandayus nenday. See Nanday Conure Nanny shad. See Gizzard Shad Nanophyte species, biological control (plants) water chestnut, 338 Nasturtium draba. See Hoary Cress National Gypsy Moth Slow the Spread (STS) program, 142 National Invasive Species Act, 703 Native species, definitions, xiii (v. 1) Natural selection, and brown anoles, 217 Naval Shipworm, 70–72 Neochetina species, biological control (plants) waterhyacinth, 342

Neodiplogrammus quadrivittatus. See sesbania stem borer Neogobius melanostomus. See Round Goby Neomusotima conspurcatalis, biological control (plants) climbing ferns, 601 Neomusotima fuscolinealis, biological control (plants) climbing ferns, 601 Nepalese browntop. See Japanese Stilt Grass New Zealand Mud Snail, xxvt (v. 1), 73–76 state-by-state occurrences, 295, 296, 298, 302, 303, 306, 308–10 Nicosulfuron, chemical control (plants) quackgrass, 488 Nightcrawler, xxiiit (v. 1), xxxv (v. 1). See also European Earthworms Nigropalallidal encephalomalacia disease, in horses, 430 Nigua. See Koster’s Curse Nile Monitor, xxivt (v. 1), 225–28 state-by-state occurrences, 297 Nintooa japonica. See Japanese Honeysuckle Niphograpta albiguttalis. See waterhyacinth moth Nitrogen fixer Australian pine, 541 brooms, 497, 500 fire tree, 556 gorse, 509–10 kudzu, 623, 627 Russian olive, 571–72 silk tree, 575 Nodding thistle. See Musk Thistle Nonindigenous Aquatic Nuisance Prevention and Control Act (1990), xv (v. 1), 85, 702 Nonnative species, xv (v. 1) Norops sagrei. See Brown Anole Norops sagrei sagrei, 214 Norops sagrei ordinates, 214 North Cascades National Park, and white pine blister rust, 34 Northern African python, 220 Northern pearly eye butterfly, and Japanese stilt grass, 468, 664 Northern Snakehead, xix (v. 1), xxiiit (v. 1), 182–85 state-by-state occurrences, 301, 306, 309 Northern watermilfoil, 321–22, 324, 325, 649 Northern wheatgrass, 487, 655 Norway Rat, xviii (v. 1), xxvit (v. 1), 259, 260, 262, 283, 287–90 state-by-state occurrences, 295–310 Noxious species, definition, xv (v. 1)

I-26 n INDEX Noxious Weed Control and Eradication Act, 704–5 Nutria, xviii (v. 1), xxiiit (v. 1), xxvi (v. 1), 290–94 ISSG 100 worst invaders, 293, 712 state-by-state occurrences, 295– 298, 300–2, 304–6, 307, 308, 309 Oberea erythrocephala, biological control (plants) leafy spurge, 398 Ohia tree, 556, 659 and strawberry guava, 577, 579 and velvet tree, 591 Old World Climbing Fern, 597–602 impacts, 684 noxious designation, 665, 667, 693 pathways of introduction, 674, 679 Octagonal-tail earthworm. See European Earthworms Oleaster. See Russian Olive Oleaster family, 568 Oncideres cingulata. See twig girdler Onopordum acanthium. See Scotch thistle Oncorhynchus mykiss. See Rainbow Trout Ophideres fullonica, biological control (plants) chocolate vine, 596 Ophioglossum japonicum. See Japanese Climbing Fern Ophiomyia lantanae, biological control (plants) lantana, 521 Ophiostoma novo-ulmi. See Dutch Elm Disease Ophiostoma ulmi. See Dutch Elm Disease Oppositeleaf Russian thistle, 412, 651 noxious designation, 666, 690 Orangeberry nightshade, 532, 661 Orange sheath tunicate. See Chain tunicate Orchids, 495, 661 Orconectes rusticus. See Rusty Crayfish Orconectes virilis. See Virile Crayfish Organ Pipe Cactus National Monument buffelgrass, 437, 438 Oriental Bittersweet, 629–33 impacts, 681, 684 noxious designation, 666, 668, 669, 671, 693 pathways of introduction, 674 and winter creeper, 641 Orseolia javanica, biological control (plants) cogongrass, 447 Orthogalumna terebrantis, biological control (plants) waterhyacinth, 342 Osteopilus septentrionalis. See Cuban Treefrog Ossabaw Island hog, 280

Oxyops vitiosa, biological control (plants) melaleuca, 561 Oyster thief (green algae), 37 Pacific mosquito fern, 327, 649 Painted butterfly, biological control (plants) Canada thistle, 348 Pale Swallow-Wort, 636–40 impacts, 678, 680, 684 noxious designation, 666, 668, 669, 671, 693 pathways of introduction, 674 Palila, and gorse, 510, 662 Pampas Grass, 460, 473–78 impacts, 679, 683, 685 noxious designation, 691 pathways of introduction, 674 Panicum amplexicaule. See West Indian Marsh Grass Paper Mulberry, 562–65 impacts, 681, 684 noxious designation, 693 pathways of introduction, 674 Paperbark tea tree. See Melaleuca Paperbark tree. See Melaleuca Papyrius papyriferus. See Paper Mulberry Parapoynx diminutalis, biological control (plants) hydrilla, 334 Paraquat, chemical control (plants) cheatgrass, 443 medusahead, 484 Parrotfeather, 322, 649 noxious designation, 665, 666, 668, 671, 689 Partridge pea, 574, 651 Pasilla. See Chinaberry Passer domesticus. See House Sparrow Passer montanus, 244 Pasto buffel. See Buffelgrass Pasture rose, 524, 657 Pathways of introduction, xxii–xxvi (v. 1) intentional, xxiiit–xxivt (v. 1) unintentional, xxiiit (v. 1) Paulownia. See Princess Tree Paulownia elongata. See elongate paulownia Paulownia fortunei. See white-flowered paulownia Paulownia imperialis. See Princess Tree Paulownia tomentosa. See Princess Tree Peacock cichlid, 198 Pea family, 349, 496, 508, 527, 572, 622, 644 Peacock fly, biological control (plants) yellow starthistle, 431 Pearl millet, 462, 655

INDEX n I-27 Pempelia genistella, biological control (plants) gorse, 511 Pennisetum ciliare. See Buffelgrass Pennisetum clandestinum. See Kikuyugrass Pennisetum conchroides. See Buffelgrass Pennisetum inclusum. See Kikuyugrass Pennisetum incomptum. See Buffelgrass Pennisetum longstylum. See Kikuyugrass Pennisetum longstylum var. clandestinum. See Kikuyugrass Pennisetum macrostachyon. See Crimson Fountain Grass Pennisetum rueppelianum. See Crimson Fountain Grass Pennisetum ruppelii. See Crimson Fountain Grass Pennisetum setaceum. See Crimson Fountain Grass Peppervine, 633, 634, 660, 661 noxious designation, 693. See also Porcelainberry Pepperweed whitetop. See Hoary Cress Perennial peppergrass. See Hoary Cress Perennial Pepperweed 404–9 impacts, 680, 683 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672 pathways of introduction, 677 Perennial snapdragon. See Yellow Toadflax Perna viridis. See Asian Green Mussel Persian ivy. See colchis ivy Persian lilac. See Chinaberry Persicaria arifolium var. perfoliatum. See Mile-A-Minute Persicaria perfoliata. See Mile-A-Minute Peruvian peppertree, 545, 659 Pet trade release boa constrictors, 220 Burmese Python, 219 Common Myna, 233 Nile Monitor, 226 Petromyzon marinus. See Sea Lamprey Phakopsora apoda, biological control (plants) kikuyugrass, 481 Phalaris setaceum. See Crimson Fountain Grass Phomopsis arnoldiae, biological control (plants) Russian olive tree, 572 Phomopsis broussonetiae, biological control (plants) paper mulberry, 564 Phothedes dulcis, biological control (plants) giant reed, 466 Phragmataecia castaneae, biological control (plants) common reed, 451

Phragmites. See Common Reed Phragmites australis ssp. australis. See Common Reed Phragmites communis. See Common Reed Phragmites communis var. berlandieri. See Common Reed Phragmites phragmites. See Common Reed Phyllachora species, biological control (plants) West Indian marsh grass, 492 Phyllocoptes fructiphilus, biological control (plants) multiflora rose, 526 Phyllonorycter myricae, biological control (plants) fire tree, 557 Phyllorhiza punctata. See Australian Spotted Jellyfish Phyllotreta ochripes, biological control (plants) garlic mustard, 372 Phymatototrichum omnivorum, biological control (plants) common mullein, 357 winter creeper, 643 Physical control (plants). See species entries Phytophthora ramorum. See Sudden Oak Death Piaropus crassipes. See Waterhyacinth Piaropus mesomelas. See Waterhyacinth Pierce’s disease, Glassy-Winged Sharpshooter as vector, 137 Pickerelweed, 342, 649 Pickerelweed family, 339 Picloram, chemical control (plants) Australian pine, 543 chinaberry, 554 common St. Johnswort, 361 gorse, 511 Japanese honeysuckle, 617 Japanese knotweed, 390 leafy spurge, 398 multiflora rose, 525 musk thistle, 403 spotted knapweed, 420 strawberry guava, 578 tropical soda apple, 534 wisteria, 647 Pigface fig. See Ice Plant Piggyback plant, 370, 651 Pilewort. See Fig Buttercup Pili grass, 438, 655 Pimienta de Brazil. See Brazilian Peppertree Pineapple guava. See Strawberry Guava Pine bark adelgid, 31 Pineland lantana, 519, 657 Pineland verbena. See pineland lantana Pine straw, and climbing ferns, 600, 601

I-28 n INDEX Pineus strobi. See Pine bark adelgid Pineywoods rooter. See Feral Pig Pink-flowered tamarisk. See Tamarisk Pink pampas grass. See Jubata Grass Pink sand verbena, 386, 651 Pink snow mold, biological control (plants) cheatgrass, 443 Pipevine, 594, 661 Piping Plover, 662 and Asiatic sand sedge, 434 and oriental bittersweet, 632 Plains bristlegrass, 437, 655 Planthopper, biological control (plants) cordgrass, 458 waterhyacinth, 342 Plant Protection Act, 704 Plasmodium relictum capistranoae. See Avian Malaria Platycephala planifrons, biological control (plants) common reed, 451 Pleuropterus cuspidatus. See Japanese Knotweed Pleuropterus zuccarinii. See Japanese Knotweed Plowing, physical control (plants). See tilling Plumeless thistle, 401, 652 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 691. See also Musk Thistle Poaceae. See grass family Poison hemlock, 374, 652 Poison ivy, 547, 661 and English ivy, 604 and kudzu, 623 Polygonaceae. See buckwheat family Polygonum cuspidatum. See Japanese Knotweed Polygonum perfoliatum. See Mile-A-Minute Polygonum zuccarinii. See Japanese Knotweed Pomacea canaliculata. See Golden Apple Snail Pomacea insularum. See Island applesnail Pondweed, 333–34, 649 Pontederiaceae. See pickerelweed family Pontederia crassipes. See Waterhyacinth Poor-man’s mustard. See Garlic Mustard Popillia japonica. See Japanese Beetle Porcelain ampelopsis. See Porcelainberry Porcelainberry, 633–36 and English ivy, 603 impacts, 684 noxious designation, 666, 668, 693 pathways of introduction, 674 Porcelain vine. See Porcelainberry Portuguese broom, noxious designation, 670, 692. See also Brooms Postemergent herbicides, xx (v. 2)

Potamopyrgus antipodarum. See New Zealand Mud Snail Potato family, 530 Potato x disease, field bindweed as host, 609 Powderpuff tree. See Silk Tree Proterorhinus marmoratus. See Tubenose goby Preemergent herbicides, xx (v. 2) Prickly glasswort. See Prickly Russian Thistle Prickly lantana. See Lantana Prickly rose, 524, 657 Prickly Russian Thistle, 409–14 and halogeton, 380 impacts, 678, 679, 683, 685 noxious designation, 665, 666, 667, 669, 691 pathways of introduction, 677 Prickly sage. See Lantana Pride of India. See Chinaberry Princess flower. See glorybush Princess Tree, 121, 565–68 impacts, 684 noxious designation, 666, 693 pathways of introduction, 674, 676 uses of, 567 Prokeleisa marginata. See planthopper Prostrate tickrefoil, 623, 652 Pseudocercospora humuli, biological control (plants) Japanese hops, 621 Pseudodaleta unipuncta. See grass army worms Pseudomonas bacteria, biological control (plants) cheatgrass, 443 kudzu, 625 Pseudophilothrips ichini, biological control (plants) Brazilian peppertree, 548 Pseudorabies, Wild Pig as carrier, 280 Psidium cattleianum. See Strawberry Guava Psidium guajava. See common guava Psidium littorale var. longipes. See Strawberry Guava Psylliodes chalcomera, biological control (plants) musk thistle, 403 Pterois miles. See devil firefish. See also Lionfish Pterois volitans. See Lionfish Pt. Reyes bird’s beak, 457, 652 Public health and well-being impacts, xxx (v. 1) Australian pine, 543 chinaberry, 553 English ivy, 605 giant hogweed, 375 Japanese hops, 620 Johnsongrass, 472 leafy spurge, 397 melaleuca, 560 paper mulberry, 563 Public Land Management Act of 2009, 706

INDEX n I-29 Puccinia juncea var. solstitialis, biological control (plants) yellow starthistle, 431 Puccinia lygodii, biological control (plants) climbing ferns, 601 Puccinia punctiformis, biological control (plants) Canada thistle, 349 Pueraria montana. See Kudzu Pueraria species. See Kudzu Puerto Rican treefrog. See Coqui Pulvinariella species. See ice plant scale insects Punk tree. See Melaleuca Purple African nightshade, 532, 657 Purpleflowering raspberry, 524, 657 Purple guava. See Strawberry Guava Purple Loosestrife, 414–17 impacts, 681, 683 ISSG 100 invasive worst, 711 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 691 pathways of introduction, 674, 675, 677 Purple lythrum. See Purple Loosestrife Purple pampas grass. See Jubata Grass Purple plague. See Velvet Tree Purple sesbane. See Rattlebox Purple starthistle, 419, 428, 652 noxious designation, 665, 666, 669, 670, 671, 691 Purplestem angelica, 373, 652 Purple strawberry guava. See Strawberry Guava Pyricularia grisea, biological control (plants) buffelgrass, 439 kikuyugrass, 481 Python molurus bivittatus. See Burmese Python Python sebae, 220 Quackgrass, 485–89 impacts, 678, 680, 683 noxious designation, 665, 666, 667, 670, 671, 672, 691 pathways of introduction, 677 Quagga Mussel, xxvt (v. 1), 76–79, 83 state-by-state occurrences, 295, 296, 298–303, 305, 306 Quaker Conure. See Monk Parakeet Quaker Parrot. See Monk Parakeet Quassia family, 585 Queen Anne’s lace, 373, 652 Rabbit flower. See Yellow Toadflax Rainbow Trout, xviii (v. 1), xxivt (v. 1), xxviii (v. 1), 166, 185–87 ISSG 100 worst invaders, 187, 711 state-by-state occurrences, 295–310

Rainbow weed. See Purple Loosestrife Rajania quinata. See Chocolate Vine Ralstonia solanacearum, biological control (plants) kahili ginger, 394 tropical soda, 534 Rambler rose. See Multiflora Rose Ramorum blight. See Sudden Oak Death Rana platernera. See Cuban Treefrog Range expansion, xv (v. 1) Range maps, xiv (v. 1) Ranunculuaceae. See buttercup family Ranunculus ficaria. See Fig Buttercup Rapana venosa. See Veined Rapa Whelk Rattlebox, 527–30 impacts, 679, 681, 682, 683, 685, 692 noxious designation, 692 Rattus norvegicus. See Norway Rat Rattus rattus. See Black Rat Razorback. See Feral Pig Red baron. See Japanese Blood Grass Redbelly tilapia, 196 Red-billed Leiothrix, and kahili ginger, 393, 662 and velvet tree, 591 Redcoat. See Common Bed Bug Red honeysuckle, 505, 657 Red Imported Fire Ant, xxvit (v. 1), xxviii (v. 1), 152–56 ISSG 100 worst invaders, 711 state-by-state occurrences, 295–98, 305, 307–10 Red lionfish. See Lionfish Red mulberry, 562, 659 Red sage. See Lantana Red sesbania. See Rattlebox Red sheath tunicate. See Chain Tunicate Red starthistle. See purple starthistle Red swamp crayfish, 89 Red wigglers. See European Earthworms Red worms. See European Earthworms Rehsonia floribunda. See Japanese Wisteria Rehsonia sinensis. See Chinese Wisteria Reptiles, 214–28 American species invasive abroad, 697 ISSG worst invaders, 712 Residuals, herbicides, xx (v. 2) Reticulated python, 220 Reynoutria. See Japanese Knotweed Reynoutria japonica, 387 Rhamnaceae. See buckthorn family Rhamnus asiatica. See Asiatic Colubrina Rhamnus splendens. See Asiatic Colubrina Rhinocyllus conicus, biological control (plants) Canada thistle, 348 musk thistle, 403

I-30 n INDEX Rhinoncomimus latipes, biological control (plants) mile-a-minute, 628 Rhinusa species, biological control (plants) toadflax, 426 Rhizedra lutosa, biological control (plants) common reed, 451 Rhizobacteria, biological control (plants) cheatgrass, 443 Rhus terebinthifolia. See Brazilian Peppertree Rhyssomatus marginatus. See sesbania seed weevil Rice eel. See Asian Swamp Eel Rice-paddy eel. See Asian Swamp Eel Richard’s pampas grass. See toe toe RIFA. See Red Imported Fire Ant Ringed Turtle-Dove, 235–36 Rio Grande ragweed, 438, 652 River herring. See Alewife Robust blackberry. See Yellow Himalayan Raspberry Rock Dove. See Rock Pigeon Rock Pigeon, xviii (v. 1), 256–59 state-by-state occurrences, 295–310 Rocky Mountain National Park, chytrid frog fungus, 19 quackgrass, 487 Roof rat. See Black Rat Root rot and Australian pine, 544 and common mullein, 357 and giant reed, 466 and winter creeper, 644 Rosa cathayensis. See Multiflora Rose Rosaceae. See rose family Rosa multiflora. See Multiflora Rose Roseau. See Common Reed Roseau cane. See Common Reed Rose family, 522, 535 Rose stemgirdler, biological control (plants) multiflora rose, 526 Round-leaved bittersweet. See Oriental Bittersweet Rough Periwinkle, 61 Round Goby, xxiv (v. 1), xxvt (v. 1), xxvii (v. 1), 187–90 state-by-state occurrences, 299, 301, 302, 305 Royal paulownia. See Princess Tree Rubus ellipticus. See Yellow Himalayan Raspberry Rubus flavus. See Yellow Himalayan Raspberry Rubus gowreephul. See Yellow Himalayan Raspberry Rugosa rose, 524, 657

Running euonymus. See running strawberry bush Running strawberry bush, 641, 657 Rush wheatgrass, 487, 655 Russian knapweed, 418–19, 428, 652 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 691 toxic, 430 Russian Olive, 568–72, 705 impacts, 680, 682, 684, 686 noxious designation, 666, 669, 693 pathways of introduction, 674, 675, 676 Russian thistle, 380. See Prickly Russian Thistle Russian tumbleweed. See Prickly Russian Thistle Russian wheatgrass, 487, 655 Russian wild boar. See Feral Pig Rusty blackhaw, 641, 657 Rusty Crayfish, xxiiit (v. 1), 93–95 state-by-state occurrences, 297, 299, 300, 301, 302, 304, 306, 309 Ryegrass, 487, 655 Sacramento Mountain thistle, and musk thistle, 402, 652 Safflower, 348, 652 Salicaire. See Purple Loosestrife Salmo trutta. See Brown Trout Salsola species. See Prickly Russian Thistle Salsola tragus. See Prickly Russian Thistle Saltcedar leaf beetle, biological control (plants) tamarisk, 585 Salt cedar. See Tamarisk Saltlover. See Halogeton Saltmarsh clubrush. See cosmopolitan bulrush Salt marsh hay. See Cordgrasses and Their Hybrids Salt meadow cordgrass. See Cordgrasses and Their Hybrids Saltwort. See Prickly Russian Thistle Salvinia. See Giant Salvinia Salvinia auriculata. See Giant Salvinia Salvinia auriculata complex, 326 Salviniaceae. See floating fern family Salvinia molesta. See Giant Salvinia Sameodes albiguttalis. See waterhyacinth moth San Clemente Island goats, 269, 270 Sand dune thistle, 402, 652 Sapindaceae. See soapberry family Sarcotheca bahiensis. See Brazilian Peppertree Sarthamnus scoparius. See Brooms Sassafras, 562, 659 Satintail. See Cogongrass. See also Brazilian satintail; California satintail Sauce-alone. See Garlic Mustard

INDEX n I-31 Saussurea species, 402 Sawbelly. See Alewife Sawtooth blackberry, 537, 539, 657 noxious designation, 667, 692 Scaldweed. See common dodder Scaly bark oak. See Australian Pine Scarlet wisteria. See Rattlebox Scheiffelin, Eugene, 238 Schinus. See Brazilian Peppertree Schinus species. See Brazilian Peppertree Schinus terebinthifolius. See Brazilian Peppertree Schistocerca americana, biological control (plants) Chinese lespedeza, 353 Schizaphiz graminum, biological control (plants) giant reed, 466 Schoenobius giganatella, biological control (plants) common reed, 451 Scientific Committee on Problems of Environment (SCOPE), xxxi (v. 1) Sclerotinia sclerotiorum, biological control (plants) Canada thistle, 349 Scolytus multistriatus. See smaller European elm bark beetle SCOPE, xxxi (v. 1) Scotch broom, 509 noxious designation, 666, 667, 670, 671, 692. See also Brooms Scotch thistle, 401, 403, 652 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 691 Scrambling nightshade. See Tampico soda apple Scrophulariaceae. See figwort family Seabeach amaranth, 434, 652 Seabeach evening primrose, 434, 652 Sea-coast marsh elder, 434, 652 Sea fig, 384, 652. See also Ice Plant Sea Lamprey, xxiv (v. 1), xxvt (v. 1), 158, 183, 190–93 state-by-state occurrences, 299, 301, 302, 305, 310 Sea sandwort, 434, 652 Sea-side arrowgrass, 455, 457, 655 Seaside knotweed, 434, 652 Sedge family, 336, 432 Sedges, 455, 546, 654, 655. See also Asiatic Sand Sedge Segmented worms, 48 Selloa. See Jubata Grass Senna obtusifolia, biological control (plants) kudzu, 625 Septoria hodgesii sp. nov, biological control (plants) fire tree, 557 Sericea lespedeza. See Chinese Lespedeza

Sericea bush clover. See Chinese Lespedeza Sericothrips staphylinus, biological control (plants) gorse, 511 Serrate spurge. See toothed spurge Sesbania flower beetle, biological control (plants) rattlebox, 529 Sesbania puniceae. See Rattlebox Sesbania seed weevil, biological control (plants) rattlebox, 529 Sesbania tripetii. See Rattlebox Sesbania stem borer, biological control (plants) rattlebox, 529 Sethoxydim, chemical control (plants) quackgrass, 488 Seven-spotted lady beetle, 149 Sewer rat. See Norway Rat Shattercane. See sorghum Sheep, plants toxic to buffelgrass, 438 common St. Johnswort, 360 halogeton, 382 Johnsongrass, 472 Shenandoah National Park, and gypsy moth, 143 Ship rat. See Black Rat Shortspike watermilfoil. See northern watermilfoil Short-tip gall midge, biological control (plants) leafy spurge, 399 Shrubby nightshade, 532, 657 Shrubby Russian thistle, 412, 657 noxious designation, 665, 666, 667, 668, 669, 670, 671, 692 Shrubs, 493–39 American species invasive abroad, 695 ISSG 100 worst invaders, 710–11 noxious designation, 692 Sicilian starthistle, 427, 652 noxious designation, 665, 666, 691 Silk Tree, 572–75 impacts, 684 noxious designation, 693, pathways of introduction, 674, 676 Silky acacia. See Silk Tree Silky bush clover. See Chinese Lespedeza Silver Carp, 164, 194–96 state-by-state occurrences, 299, 300 Silverberry, 570, 655 Silver buffaloberry, 570, 656 Silverleaf nightshade, 532, 657 noxious designation, 665, 666, 667, 669, 670, 671, 692 Silverleaf whitefly, and tropical soda apple as host, 533–34

I-32 n INDEX Silver pampas grass. See Pampas Grass Silversword, 356, 657 Silverthorn, 570, 658 Simaroubaceae. See quassia family Simberloff, Daniel, xxxi (v. 1) Sipha species. See sugarcane aphids Sisymbrium alliaria. See Garlic Mustard Sisymbrium officinalis. See Garlic Mustard Skipjack. See Gizzard Shad Slender-flowered thistle, 401, 652 Slender lespedeza, 350–51, 652 Slender perennial peppercress. See Perennial Pepperweed Slender Russian thistle, 411, 652 noxious designation, 665, 666, 691 Slender seapurslane, 434, 652 Slippery mullein. See moth mullein Slow paralysis virus (SPV), bee virus, 105–6 Small Asian mongoose. See Indian Mongoose Small cordgrass, 452, 655. See also Cordgrasses and Their Hybrids Small crowfoot. See Fig Buttercup Smaller European elm bark beetle, 22, 23, 24 Small-flowered morning glory. See Field Bindweed Small-flowered tamarisk. See Tamarisk Small Indian mongoose. See Indian Mongoose Small-leaf climbing fern. See Old World Climbing Fern Smooth brome, 440, 655 noxious designation, 692 Smooth cordgrass. See Cordgrasses and Their Hybrids Smooth cordgrass hybrid. See Cordgrasses and Their Hybrids Smooth rose, 524, 658 Snow-on-the-mountain. See Goutweed Snowpeaks raspberry, 537, 658 noxious designation, 667, 692 Soapberry family, 548 Soap bush. See Koster’s Curse SOD. See Sudden Oak Death Sodom apple. See Tropical Soda Apple Sod-web worm, Canada thistle host, 347 Soft brome, 440, 655 noxious designation, 692 Soft chess. See Cheatgrass Soil Conservation Service. See U.S. Department of Agriculture Soil Conservation Service Solanaceae. See potato family Solanum chloranthum. See Tropical Soda Apple Solanum khasianum var. chatterjeeanum. See Tropical Soda Apple Solanum viarum. See Tropical Soda Apple

Solanum viridiflorum. See Tropical Soda Apple Solarization, physical control (plants). See mulching or tarping Soldierwood, 493, 658 Solenopsis invicta. See Red Imported Fire Ant Solenopsis richteri. See Black imported fire ant Sonoran Desert weedwackers, 438 Sophonia rufostachia. See two-spotted leafhopper Sorghum, 470, 472, 655 Sorghum halepense. See Johnsongrass Sorghum miliaceum. See Johnsongrass Southern house mosquito, as disease vectors, 1, 3, 8, 9 South Texas. See Rio Grande ragweed Soybean loper, 664, and tropical soda apple as host, 533–34 Spanish broom, noxious designation, 667, 670, 671, 692. See also Brooms Spanish gold. See Rattlebox Spanish mustang, 271–72 Spanish reed. See Giant Reed Spartina species. See Cordgrasses and Their Hybrids Spartium junceum. See Brooms Spartium scoparium. See Brooms Speargrass. See Cogongrass Species Survival Commission (SSC), ISSG 100 worst invasive species, 710–12 Sphenophorus entus vestitus, biological control (plants) kikuyugrass, 481 Spiked loosestrife. See Purple Loosestrife Spike watermilfoil. See Eurasian Watermilfoil Spiny Water Flea, xxiv (v. 1), 95–99 state-by-state occurrences, 301, 302, 305, 306, 309 Spirochetes bacterium, 3 Spissistulus festinus. See three-cornered alfalfa leaf hopper Spotted jellyfish. See Australian Spotted Jellyfish Spotted knapweed, 417–21 impacts, 679, 680, 683 noxious designatioins, 665, 666, 667, 668, 669, 670, 671, 672, 691 pathways of introduction, 677 Spotted Tilapia, 196–98 state-by-state occurrences, 296, 297, 303. See also European Starling Spurge family, 395 Spurgia esulae. See short-tip gall midge Spurious mullein. See moth mullein Squarrose knapweed, 419, 652 noxious designation, 665, 666, 670, 671, 691 Staff-tree family, 629

INDEX n I-33 Staff-vine family, 640 Staghorn sumac, 586, 658 Star thistles, 402. See also Yellow Starthistle St. Augustine grass, 479, 655 St. Barnaby’s thistle. See Yellow Starthistle Steele, Dr. Allen, 4 Steelhead (coastal rainbow trout), 185, 186 St. Johnswort. See Common St. Johnswort Stinking shumac. See Tree of Heaven Stone plant family, 383 Strangleweed. See Japanese Dodder Strawberry Guava, 279, 576–79 impacts, 678, 682, 684, 686 ISSG 100 worst invaders, 711 noxious designation, 693 pathways of introduction, 674, 676 Streptopelia decaocto. See Eurasian Collared-Dove Streptopelia risoria. See Ringed Turtle-Dove Strophocaulos arvensis. See Field Bindweed Sturnus vulgaris. See European Starling Sudangrass, 470, 655 noxious designation, 667 Sudden Oak Death, xix (v. 1), 25–29 state-by-state occurrences, 296, 306 Sugarcane aphids, biological control (plants) kikuyugrass, 481 Sulfometuron, chemical control (plants) Japanese honeysuckle, 617 Japanese hops, 621 Sumac family, 544 Summer cypress. See burning bush Sun sensitivity in humans and livestock common St. Johnswort, 360 giant hogweed, 375 Sun spurge. See madwoman’s milk Sunflower family, 344, 399, 417, 427 Surfactant, herbicides, xx (v. 2) Surinam cherry, 659 and strawberry guava, 578 Sus scrofa. See Feral Pig Susumber. See turkey berry Swallow-worts, 636–40 impacts, 678, 680, 684 noxious designation, 666, 668, 669, 671, 693 pathways of introduction, 674 Swamp beaver. See Nutria Swamp dodder. See common dodder Swamp fly-honeysuckle, 505, 658 Swamp rose, 524, 658 Swamp verbena, 414, 652 Sweetberry honeysuckles, 505, 658 Sweet breath of spring. See winter honeysuckle Sweetbriar rose, 524, 658

Sweet cicely, 370, 653 Sweet gale family, 554 Swine, plants toxic to, 360 Swine brucellosis, Wild Pig as carrier, 280 Synchytrium puerariae, biological control (plants) kudzu, 625 Systemic herbicides, xx (v. 2) Taeniatherum asperum. See Medusahead Taeniatherum caput-medusae. See Medusahead Taeniatherum crinitum. See Medusahead Tahiti, 591, 592 Tall wheatgrass, 487, 655 Tall whitetop. See Perennial Pepperweed Tamaricaceae. See tamarisk family Tamarisk, 579–85 impacts, 682, 684, 686 ISSG 100 worst invaders, 711 noxious designation, 666, 668, 669, 670, 671, 672, 693 pathways of introduction, 674, 676 Tamarix chinensis. See Five-stamen Tamarisk and Chinese Tamarisk Tamarix gallica. See French Tamarisk Tamarix parviflora. See Small-flowered Tamarisk Tamarix ramossissima. See Pink-flowered Tamarisk Tamarix species. See Tamarisk Tampico soda apple. See wetlands nightshade Tanglehead. See pili grass Taosa species, biological control (plants) waterhyacinth, 342 Tatarian honeysuckle, noxious designation, 666, 668, 669, 671, 692 and Japanese honeysuckle, 614. See also Exotic Bush Honeysuckles Tebuthiuron, chemical control (plants) buffelgrass, 439 Japanese honeysuckle, 617 Tectococcus ovatus, biological control (plants) strawberry guava, 578 Teleonemia scrupulosa, biological control (plants) lantana, 521 Teline monspessulanus. See Brooms Tender fountain grass. See Crimson Fountain Grass Teredo navalis. See Naval Shipworm Terellia ruficauda, biological control (plants) Canada thistle, 348 Tetralopha scortealis. See lespedeza webworm Tetranychus lintearis, biological control (plants) gorse, 511 Tetranychus urticae, Japanese honeysuckle as host, 617

I-34 n INDEX Texas umbrella chinaberry, 552, 659 Texas umbrella tree. See Texas umbrella chinaberry Thai eggplant. See turkey berry Thatch bromegrass. See Cheatgrass Theodore Roosevelt National Park, and feral horses, 271, 272, 273 Theory of Island Biogeography, The (MacArthur and Wilson), xxxi (v. 1) Thorny olive. See silverthorn Three-cornered alfalfa leaf hopper, biological control (plants) Chinese lespedeza, 353 Three-leaf akebia, 594, 661 Thrypticus species, biological control (plants) waterhyacinth, 342 Tick quackgrass, 487, 655 Tilapia, ISSG 100 worst invaders, 711 waterhyacinth control, 342. See also Spotted Tilapia Tilapia mariae. See Spotted Tilapia Tilapia zilli. See Redbelly tilapia Tilling, physical control (plants) cheatgrass, 442 cogongrass, 446 dyer’s woad, 365 field bindweed, 609 medusahead, 484 musk thistle, 403 quackgrass, 488 Timandra convectaria, biological control (plants) mile-a-minute, 629 Timandra griseata, biological control (plants) mile-a-minute, 629 Tingis ampliata, biological control (plants) Canada thistle, 349 Tinker’s penny, 359, 653 Tipton weed. See Common St. Johnswort Tithymalus esula. See Leafy Spurge Toadflax, 421–26 impacts, 678, 679, 680, 683, 686 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 690 pathways of introduction, 674, 675 Tobacco budworm, 664 Japanese honeysuckle as host, 617 tropical soda apple as host, 533–34 Tobacco hornworm, 664 tropical soda apple as host, 533–34 Tobacco leaf curl, biological control (plants) Japanese honeysuckle, 617 Tobacco mild green mosaic tobamovirus, biological control (plants) tropical soda apple, 534

Toe toe, 475, 655 Tomato hornworm, 664 tropical soda apple as host, 533–34 Tomato pinworm, 664 tropical soda apple as host, 533–34 Tomato spotted wilt, field bindweed as host, 609 Tomato weed. See silverleaf nightshade Toothed spurge, 396, 653 Toothworts, 370, 371, 650, 653 Tordon, chemical control (plants) gorse, 511 Torrey’s nightshade. See western horsenettle Toxicodendron altissima. See Tree of Heaven Toxic plants brooms, 500 buffelgrass, 438 chinaberry, 553 common St. Johnswort, 360 English ivy, 605 field bindweed, 609 giant hogweed, 375 halogeton, 382 Johnsongrass, 472 kikuyugrass, 480 Koster’s curse, 517 lantana, 521 leafy spurge, 397–98 Oriental bittersweet, 632 rattlebox, 529 toadflax, 425 tropical soda apple, 531 yellow starthistle, 430 Trabutina mannipara, biological control (plants) tamarisk, 585 Trapa bicornis. See devil’s pod Trapa bispinosa. See Water Chestnut Trapaceae. See water caltrop family Trapa natans. See Water Chestnut Trapa natans var. bispinosa. See Water Chestnut Trapa natans var. natans. See Water Chestnut Trapdoor snail. See Chinese Mystery Snail Trap-neuter-release (TNR) programs, feral cats, 268 Tree of Heaven, 248, 585–89 impacts, 684 noxious designation, 666, 668, 669, 671, 693 pathways of introduction, 674 uses of, 588 Trees, 540–93 American species invasive abroad, 695 ISSG 100 worst invaders, 710–11 noxious designation, 692–93 Trichapion latrivetre. See sesbania flower beetle

INDEX n I-35 Trichomonas gallinae parasite, Eurasian Collared-Dove as host, 236 Trichosirocalus horridus, biological control (plants) musk thistle, 403 Trichosporium visiculosum, biological control (plants) Australian pine, 543 Triclopyr, chemical control (plants) Asiatic colubrina, 495 Australian pine, 543 Brazilian peppertree, 547 brooms, 501 carrotwood, 550 chinaberry, 554 Chinese lespedeza, 352 chocolate vine, 596 common mullein, 36 English ivy, 605 Eurasian watermilfoil, 324 exotic bush honeysuckles, 506 giant hogweed, 375 gorse, 511 Japanese barberry, 514 Japanese knotweed, 390 Koster’s curse, 518 kudzu, 625 multiflora rose, 525 musk thistle, 403 Oriental bittersweet, 632 paper mulberry, 564 porcelainberry, 635 prickly Russian thistle, 413 princess tree, 568 purple loosestrife, 417 rattlebox, 529 strawberry guava, 578 swallow-worts, 640 tamarisk, 585 tree of heaven, 588 tropical soda apple, 534 velvet tree, 592 winter creeper, 643 wisteria, 647 yellow Himalayan raspberry, 538, 539 Triploid grass carp, 174 Triticum repens. See Quackgrass Triticum vaillantianum. See Quackgrass Trompetilla. See West Indian Marsh Grass Tropical curlygrass fern, 600, 653 Tropical Soda Apple, 530–35 impacts, 678, 680, 681, 684, 685 noxious designation, 665, 666, 668, 669, 670, 671, 692 pathways of introduction, 677

Trumpet creeper, 645, 661 Trumpet grass. See West Indian Marsh Grass Tubenose goby, 188 Tuckeroo tree. See Carrotwood Tucson Mountain Park, 438 Tumbleweed. See Prickly Russian Thistle Tunicates, 39–45 Turkey berry, 531, 658 noxious designation, 665, 666, 667, 668, 669, 670, 671, 692 Turkeyfish, 175 Turtles, and Australian pine, 543 Tu Si Zi. See Japanese Dodder Twig girdler, biological control (plants) Australian pine, 543 Twinberry honeysuckle. See bearberry honeysuckle Twitchgrass. See Quackgrass 2,4-D, chemical control (plants) common St. Johnswort, 361 dyer’s woad, 365 Eurasian watermilfoil, 324 field bindweed, 609 gorse, 511 Japanese honeysuckle, 617 leafy spurge, 398 multiflora rose, 525 musk thistle, 403 prickly Russian thistle, 413 spotted knapweed, 420 strawberry guava, 578 tamarisk, 584 velvet tree, 592 water chestnut, 338 waterhyacinth, 342 Twoleaf toothwort. See crinkleroot Two-spotted leafhopper, biological control (plants) fire tree, 557 Tyta luctuosa, biological control (plants) field bindweed, 609 Ugena microphylla. See Old World Climbing Fern Ulex europaeus. See Gorse Umbrellatree. See Chinaberry Unaspis euonumi, biological control (plants) winter creeper, 643 Unintentional pathways of introduction, xxvt (v. 1), 676–77 Upland frog. See African Clawed Frog Urophora species, biological control (plants) spotted knapweed, 421 yellow starthistle, 431 Uruguayan pampas grass. See Pampas Grass

I-36 n INDEX U.S. Department of Agriculture Soil Conservation Service, xvi (v. 2), xviii (v. 2), 437, 499, 524, 623 Ustilagao bulleta, biological control (plants) cheatgrass, 443 Vaccinium flase bottom, field bindweed as host, 609 Vanessa cardui. See painted butterfly Varanus niloticus. See Nile Monitor Varanus salvator. See Asian water monitor Variable leaf waterhyacinth, 339–40, 649 Variable watermilfoil, 322, 649 noxious designation, 666, 667, 668, 671, 689 Varnish tree. See Tree of Heaven Varroa destuctor. See Varroa Mite Varroa Mite, xix (v. 1), 102–5 Africanized Honey Bee as host, 103, 108 state-by-state occurrences, 295–310 Veined Rapa Whelk, 79–82 state-by-state occurrences, 308 Velvet dock. See Common Mullein Velvet Tree, 515, 589–93 impacts, 682, 684 and Koster’s curse, 515 noxious designation, 667, 693 pathways of introduction, 674 Verbascum thapsus. See Common Mullein Verbenaceae. See verbena family Verbena family, 518 Vertebrates, 157–294 American species invasive abroad, 697 amphibians, 201–14 birds, 228–59 fish, 157–201 ISSG 100 worst invaders, 711–12 mammals, 259–94 reptiles, 214–28 Verticillium dahliae, biological control (plants) tree of heaven, 589 Vincetoxicum medium. See Pale Swallow-Wort Vincetoxicum nigrum. See Black Swallow-Wort Vincetoxicum rossicum. See Pale Swallow-Wort Vines, 594–644 ISSG 100 worst invaders, 710–11 noxious designation, 693 Violets, 370, 653 Violet tunicate, 39 Virginia creeper, 619, 661 Virginia cutgrass, 467, 656 Virginia rose, 524, 658 Virile crayfish, 93, 94 Vitaceae. See grape family

Vitis brevipedunculata. See Porcelainberry Viviparus georgianus, 59 VOC. See volatile organic compound Volatile organic compound, and kudzu, 624 Wahiawa Botanical Garden, and velvet tree, 590 Waiawi. See Strawberry Guava Walking Catfish, xviii (v. 1), 198–201 ISSG 100 worst invaders, 200, 711 state-by-state occurrences, 297 Wall louse. See Common Bed Bug Wasps, biological control (plants) Australian pine, 543 Brazilian peppertree, 548 multiflora rose, 526 velvet tree, 592 Water caltrop. See Water Chestnut Water caltrop family, 335 Water Chestnut, 335–39 impacts, 682, 685 noxious designation, 665, 666, 667, 668, 669, 670, 671, 689 pathways of introduction, 674, 677 Water clover, 327, 330, 650 Water fern. See Giant Salvinia Waterhyacinth, xviii (v. 1), 173, 293, 336, 339–43, 522 impacts, 680, 681, 682, 685 ISSG 100 worst invasives, 710 noxious designation, 665, 666, 668, 669, 670, 671, 689 pathways of introduction, 674, 677 Waterhyacinth moth, biological control (plants) waterhyacinth, 342 Water milfoil family, 322 Water spangles. See common salvinia Water straw grass. See West Indian Marsh Grass Water thyme. See Hydrilla Water velvet. See Giant Salvinia Wauke. See Paper Mulberry Wavyleaf thistle, 345, 653 Weevils, biological control (plants) Australian pine, 543 brooms, 501 Canada thistle, 348, 349 common mullein, 357 Eurasian watermilfoil, 324, 325 garlic mustard, 372 giant salvinia, 330 gorse, 511 kudzu, 625 mile-a-minute, 628–29 musk thistle, 403 purple loosestrife, 417

INDEX n I-37 rattlebox, 529 tropical soda apple, 534 spotted knapweed, 421 toadflax, 426 tropical soda apple, 534 velvet tree, 592 water chestnut, 338 waterhyacinth, 342 yellow starthistle, 430–31 West African pennisetum. See Kikuyugrass Western horsenettle, 533, 653 noxious designation, 666, 691 Western morning glory, 607, 661 Western mosquito fish. See Mosquitofish Western wheatgrass, 442, 487, 656 West Indian mahogany, 495, 659 West Indian Marsh Grass, 489–92 impacts 682, 683 noxious designation, 692 pathways of introduction, 675, 677 West Indian raspberry, 537, 658 noxious designation, 692 West Nile Virus, xix (v. 1), 7–10 mosquito as vector, 119 state-by-state occurrences, 295–310 West Virginia white butterfly, and garlic mustard, 371 Wetlands nightshade, 531–32, 661 noxious designation, 665, 666, 667, 668, 669, 670, 671, 693 Wetlands soda apple. See wetlands nightshade Wharf rat. See Norway Rat Whin. See Gorse Whirling disease parasite, salmonids, 187 Whistling pine. See Australian Pine White amur. See Grass Carp White avens, 370, 653 White basswood, 562, 659 White bottlebrush tree. See Melaleuca White cedar. See Chinaberry White-flowered paulownia, 565–66, 659 White ginger, 391, 392, 393, 394, 653 White grass. See Virginia cutgrass White herring. See Alewife White horsenettle. See silverleaf nightshade White lace bryozoan. See Lacy Crust Bryozoan White leaf rust, biological control (plants) perennial pepperweed, 409 White-lipped python, 220 White mulberry, 562, 659 White Pine Blister Rust, 29–35 state-by-state occurrences, 296–310 White ricefield eel. See Asian Swamp Eel

White-spotted jellyfish. See Australian Spotted Jellyfish White swallow-wort, 637, 661 noxious designation, 671, 693 White-tailed deer, 663 and earthworms, 51 White top. See Hoary Cress White-winged parakeet, 250 Wild blackberry. See Yellow Himalayan Raspberry Wild cane. See Giant Reed Wild cinnamon, 495, 659 Wild coffee. See Asiatic Colubrina Wild cucumber, 619, 661 Wild donkey. See Feral Burro Wild Free-Roaming Horse and Burro Act (1971), 273, 274 Wild ginger. See Kahili Ginger Wild grape, 603, 661. See also Porcelainberry Wild horse. See Feral Horse Wild oats. See Cheatgrass Wild parsnip, 373, 653 Wild pigs. See Feral Pig Wild raspberry. See Yellow Himalayan Raspberry Wild rye, 483, 656. See also Quackgrass Wild snapdragon. See Toadflax Wilelaiki. See Brazilian Peppertree Willow Flycatcher, 662 and giant reeds, 464 Wilson, E. O., xxxi (v. 1) Windwitch. See Prickly Russian Thistle Winter creeper, 640–44 impacts, 684 noxious designation, 693 pathways of introduction, 674 Winter honeysuckle, 504–5, 658 Winter shad. See Gizzard Shad Wiregrass. See Quackgrass Wisteria, 644–47 impacts, 681, 684 noxious designation, 693 pathways of introduction, 674 Wistar Institute, Philadelphia, 289 Wisteria sinensis. See Chinese Wisteria Wisteria floribunda. See Japanese Wisteria Witchgrass. See Quackgrass Witchweed. See Prickly Russian Thistle WNV. See West Nile Virus Wolf’s milk. See Leafy Spurge Wolf’s primrose, 386, 653 Woman’s tongue, 572–73, 660 Woodbine. See Japanese Honeysuckle Woolly. See Hemlock Woolly Adelgid

I-38 n INDEX Wooly Dutchman’s pipe, 594, 661 and climbing ferns, 600 Wooly mullein. See Common Mullein World Conservation Union (IUCN), ISSG 100 worst invasive alien species, 710–12 Wormwood, 434, 658 Wrinkle wrinkle. See Common Periwinkle Xenopus laevis. See African Clawed Frog Xylella fastidiosa, glassy-winged sharpshooter as vector, 137. See also bacterial leaf scorch Yellow anaconda, 220 Yellow-brown stink bug. See Brown Marmorated Stink Bug Yellow cane. See Common Reed Yellow-chevroned parakeet, 250 Yellow cockspur. See also Yellow Starthistle Yellow eel. See Asian Swamp Eel Yellow fever mosquito, 117 Yellow ginger, 391–92, 393, 394, 653 Yellow Himalayan Raspberry, 535–39 impacts, 684 ISSG 100 worst invaders, 711 noxious designation, 667, 692 pathways of introduction, 676 Yellow honeysuckle, 505, 658 Yellow raspberry. See Yellow Himalayan Raspberry Yellow sage. See Lantana

Yellowspine thistle, 345, 653 Yellow Starthistle, 402, 427–31 impacts, 679, 680, 683, 685, 686 noxious designation, 665, 666, 667, 668, 669, 670, 671, 691 pathways of introduction, 677 Yellow toadflax. See Toadflax Yersinia pestis, carried by black rats’ fleas, 262, 290 Zacate buffel. See Buffelgrass Zapata bladderpod, 438, 653 Zasloff, Dr. Michael, 204 Zauclophora pelodes, biological control (plants) Australian pine, 543 Zebrafish. See Lionfish Zebra Mussel, xix (v. 1), xxiv (v. 1), xxvt (v. 1), xxvii (v. 1), xxviii (v. 1), xxix (v. 1), 58, 76, 77, 78, 79, 80, 82–86, 189, 190 ISSG 100 worst invaders, 711 state-by-state occurrences, 295–10 Zingiberaceae. See ginger family Zonate leafspot, biological control (plants) tree of heaven, 589 Zooids bryozoan young, 36, 37 tunicate young, 39–0, 42 Zosterops japonicas. See Japanese White-Eye Zyginidia guyumi, biological control (plants) giant reed, 466

n About the Authors SUSAN L. WOODWARD received her PhD in Geography—with a specialization in biogeography—from the University of California, Los Angeles in 1976. Her doctoral research included three years along the Lower Colorado River studying feral burros, considered by some then and now to be an invasive species. When her work began, the burro (along with the feral horse) had just been placed under the jurisdiction of the U.S. Bureau of Land Management (BLM), which had a federal mandate to manage this living symbol of the Old West. The results of her field work provided the BLM with some of its earliest baseline data on burro population biology and ecology. Dr. Woodward taught biogeography, physical geography, and human ecology for 22 years at Radford University in Virginia, before retiring in 2006. She is the author of Biomes of Earth (2003) and served as general editor and author of three volumes for Greenwood Guides to Biomes of the World (2009). JOYCE A. QUINN retired from California State University, Fresno as professor emerita after 21 years of teaching a variety of courses in physical geography and mapping techniques. She earned an MA from the University of Colorado and a PhD from Arizona State University, both in Geography, specializing in the effect of climate and soils on the distribution of plants. She has traveled extensively throughout North America, Latin America, Europe, northern and southern Africa, Uzbekistan, Nepal, China, Southeast Asia, Micronesia, and elsewhere. She is a member of the Cactus and Succulent Society of America and the California Invasive Plant Council and is the author of two volumes of Greenwood Guides to Biomes of the World (2009).

n Encyclopedia of Invasive Species

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n Encyclopedia

of Invasive Species From Africanized Honey Bees to Zebra Mussels Volume 2: Plants

Susan L. Woodward and Joyce A. Quinn

Copyright 2011 by ABC-CLIO, LLC All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, except for the inclusion of brief quotations in a review, without prior permission in writing from the publisher. Library of Congress Cataloging-in-Publication Data Woodward, Susan L., 1944 Jan. 20– Encyclopedia of invasive species : from africanized honey bees to zebra mussels / Susan L. Woodward and Joyce A. Quinn. p. cm. Includes bibliographical references and index. ISBN 978–0–313–38220–8 (cloth : alk. paper) — ISBN 978–0–313–38221–5 (ebook) 1. Introduced organisms—Encyclopedias. I. Quinn, Joyce Ann. II. Title. QH353.W66 2011 578.60 2—dc23 2011026543 ISBN: 978–0–313–38220–8 EISBN: 978–0–313–38221–5 15 14 13 12 11

1 2 3 4 5

This book is also available on the World Wide Web as an eBook. Visit www.abc-clio.com for details. Greenwood An Imprint of ABC-CLIO, LLC ABC-CLIO, LLC 130 Cremona Drive, P.O. Box 1911 Santa Barbara, California 93116-1911 This book is printed on acid-free paper Manufactured in the United States of America

n Contents General Introduction: Invasive Species—Concepts and Issues n xiii VOLUME 1: INVASIVE MICROORGANISMS, FUNGI, AND ANIMALS Preface n xxxv Alphabetical List of Invasive Microorganisms, Fungi, and Animal Entries n xxxix Microorganisms Avian Malaria (Plasmodium relictum capistranoae) n 1 Lyme Disease Bacterium (Borrelia burgdorferi) n 3 West Nile Virus (West Nile Virus) n 7 Fungi Bat White-Nose Syndrome Fungus (Geomyces destructans) n 11 Chestnut Blight Fungus (Cryphonectria parasitica) n 14 Chytrid Frog Fungus (Batrachochytrium dendrobatidis) n 18 Dutch Elm Disease Fungi (Ophiostoma novo-ulmi and O. ulmi) n 21 Sudden Oak Death (Phytophthora ramorum) n 25 White Pine Blister Rust (Cronartium ribicola) n 29 Invertebrates Bryozoan Lacy Crust Bryozoan (Membranipora membranacea) n 36 Tunicates Chain Tunicate (Botrylloides violaceus) n 39 Colonial Tunicate (Didemnum vexillum) n 42 Cnidarian Australian Spotted Jellyfish (Phyllorhiza punctata) n 45

vi n CONTENTS

Annelid worms European Earthworms (Lumbricus terrestris, L. rubellus, Aporrectodea caliginosa, Dendrobaena octaedra, and others) n 48 Mollusks Asian Clam (Corbicula fluminea) n 53 Asian Green Mussel (Perna viridis) n 56 Chinese Mystery Snail (Cipangopaludina chinensis malleata) n 58 Common Periwinkle (Littorina littorea) n 61 Giant African Snail (Achatina fulica) n 64 Golden Apple Snail (Pomacea canaliculata) n 67 Naval Shipworm (Teredo navalis) n 70 New Zealand Mud Snail (Potamopyrgus antipodarum) n 73 Quagga Mussel (Dreissena rostriformis bugensis) n 76 Veined Rapa Whelk (Rapana venosa) n 79 Zebra Mussel (Dreissena polymorpha) n 82 Crustaceans Chinese Mitten Crab (Eriocheir sinensis) n 86 Green Crab (Carcinus maenas) n 90 Rusty Crayfish (Orconectes rusticus) n 93 Spiny Water Flea (Bythotrephes longimanus) n 95 Arachnids Honeybee Tracheal Mite (Acarapis woodi) n 99 Varroa Mite (Varroa destructor) n 102 Insects Africanized Honey Bee (Apis mellifera scutellata) n 106 Argentine Ant (Linepithema humile) n 110 Asian Longhorned Beetle (Anoplophora glabripennis) n 113 Asian Tiger Mosquito (Aedes albopictus) n 116 Brown Marmorated Stink Bug (Halyomorpha halys) n 120 Common Bed Bug (Cimex lectularius) n 123 Emerald Ash Borer (Agrilus planipennis) n 127

CONTENTS n vii

Formosan Subterranean Termite (Coptotermes formosanus) n 131 Glassy-Winged Sharpshooter (Homalodisca vitripennis) n 134 Gypsy Moth (Lymantria dispar) n 138 Hemlock Woolly Adelgid (Adelges tsugae) n 142 Japanese Beetle (Popillia japonica) n 146 Multicolored Asian Lady Beetle (Harmonia axyridis) n 148 Red Imported Fire Ant (Solenopsis invicta) n 152 Vertebrates Fish Alewife (Alosa pseudoharengus) n 157 Asian Swamp Eel (Monopterus albus) n 160 Bighead Carp (Hypophthalmichthys nobilis) n 163 Brown Trout (Salmo trutta) n 166 Gizzard Shad (Dorosoma cepedianum) n 168 Grass Carp (Ctenopharyngodon idella) n 172 Lionfish (Pterois volitans / P. miles) n 175 Mosquitofish (Gambusia affinis and G. holbrooki) n 178 Northern Snakehead (Channa argus) n 182 Rainbow Trout (Oncorhynchus mykiss) n 185 Round Goby (Neogobius melanostomus) n 187 Sea Lamprey (Petromyzon marinus) n 190 Silver Carp (Hypophthalmichthys molitrix) n 194 Spotted Tilapia (Tilapia mariae) n 196 Walking Catfish (Clarias batrachus) n 198 Amphibians African Clawed Frog (Xenopus laevis) n 201 American Bullfrog (Lithobates catesbeianus) n 205 Coqui (Eleutherodactylus coqui) n 208 Cuban Treefrog (Osteopilus septentrionalis) n 211 Reptiles Brown Anole (Norops [=Anolis] sagrei) n 214 Burmese Python (Python molurus bivittatus) n 217 Green Iguana (Iguana iguana) n 221

viii n CONTENTS

Nile Monitor (Varanus niloticus) n 225 Birds Cattle Egret (Bubulcus ibis) n 228 Common Myna (Acridotheres tristis) n 232 Eurasian Collared-Dove (Streptopelia decaocto) n 234 European Starling (Sturnus vulgaris) n 237 House Finch (Carpodacus mexicanus) n 240 House Sparrow (Passer domesticus) n 243 Japanese White-Eye (Zosterops japonicus) n 246 Monk Parakeet (Myiopsitta monachus) n 248 Mute Swan (Cygnus olor) n 252 Rock Pigeon (Columba livia) n 256 Mammals Black Rat (Rattus rattus) n 259 Feral Burro (Equus asinus) n 262 Feral Cat (Felis silvestris catus) n 265 Feral Goat (Capra hircus) n 268 Feral Horse (Equus caballus) n 271 Feral Pig (Sus scrofa) n 275 House Mouse (Mus musculus) n 281 Indian Mongoose (Herpestes javanicus) n 284 Norway Rat (Rattus norvegicus) n 287 Nutria (Myocastor coypus) n 290 State-by-State Occurrences of Invasive Microorganisms, Fungi, and Animals n 295 Glossary n 311 Index n I-1 VOLUME 2: INVASIVE PLANT SPECIES Preface n xiii Invasive Plants in the United States: A Brief Overview n xvii Alphabetical List of Invasive Plant Entries n xxiii

CONTENTS n ix

Aquatic Plants Eurasian Watermilfoil (Myriophyllum spicatum) n 321 Giant Salvinia (Salvinia molesta) n 326 Hydrilla (Hydrilla verticillata) n 331 Water Chestnut (Trapa natans) n 335 Waterhyacinth (Eichhornia crassipes) n 339 Forbs Canada Thistle (Cirsium arvense) n 344 Chinese Lespedeza (Lespedeza cuneata) n 349 Common Mullein (Verbascum thapsus) n 353 Common St. Johnswort (Hypericum perforatum) n 358 Dyer’s Woad (Isatis tinctoria) n 362 Fig Buttercup (Ficaria verna) n 366 Garlic Mustard (Alliaria petiolata) n 369 Giant Hogweed (Heracleum mantegazzianum) n 372 Goutweed (Aegopodium podagraria) n 376 Halogeton (Halogeton glomeratus) n 379 Ice Plant and Crystalline Ice Plant (Carpobrotus edulis and Mesembryanthemum crystallinum) n 383 Japanese Knotweed (Fallopia japonica) n 387 Kahili Ginger (Hedychium gardnerianum) n 391 Leafy Spurge (Euphorbia esula) n 395 Musk Thistle (Carduus nutans) n 399 Perennial Pepperweed and Hoary Cress (Lepidium latifolium and Cardaria draba) n 404 Prickly Russian Thistle (Salsola tragus) n 409 Purple Loosestrife (Lythrum salicaria) n 414 Spotted Knapweed (Centaurea stoebe) n 417 Toadflax (Linaria dalmatica ssp. dalmatica and Linaria vulgaris) n 421 Yellow Starthistle (Centaurea solstitialis) n 427 Graminoids Asiatic Sand Sedge (Carex kobomugi) n 432 Buffelgrass (Pennisetum ciliare) n 435

x n CONTENTS

Cheatgrass (Bromus tectorum) n 439 Cogongrass (Imperata cylindrica) n 443 Common Reed (Phragmites australis ssp. australis) n 447 Cordgrasses and Their Hybrids (Spartina alterniflora, Spartina densiflora, Spartina patens, Spartina anglica, and Spartina alterniflora x foliosa n 452 Crimson Fountain Grass (Pennisetum setaceum) n 458 Giant Reed (Arundo donax) n 462 Japanese Stilt Grass (Microstegium vimineum) n 466 Johnsongrass (Sorghum halepense) n 469 Jubata Grass and Pampas Grass (Cortaderia jubata and Cortaderia selloana) n 472 Kikuyugrass (Pennisetum clandestinum) n 478 Medusahead (Taeniatherum caput-medusae) n 481 Quackgrass (Elymus repens) n 485 West Indian Marsh Grass (Hymenachne amplexicaulis) n 489 Shrubs Asiatic Colubrina (Colubrina asiatica) n 493 Brooms (Cytisus scoparius, Spartium junceum, Genista monspessulana, and Cytisus striatus) n 496 Exotic Bush Honeysuckles (Lonicera maackii, L. morrowii, L. tatarica, and L. x bella) n 502 Gorse (Ulex europaeus) n 508 Japanese Barberry (Berberis thunbergii) n 512 Koster’s Curse (Clidemia hirta) n 515 Lantana (Lantana camara) n 518 Multiflora Rose (Rosa multiflora) n 522 Rattlebox (Sesbania punicea) n 527 Tropical Soda Apple (Solanum viarum) n 530 Yellow Himalayan Raspberry (Rubus ellipticus) n 535 Trees Australian Pine (Casuarina equisetifolia) n 540 Brazilian Peppertree (Schinus terebinthifolius) n 544

CONTENTS n xi

Carrotwood (Cupaniopsis anacardioides) n 548 Chinaberry (Melia azedarach) n 551 Fire Tree (Morella faya) n 554 Melaleuca (Melaleuca quinquenervia) n 557 Paper Mulberry (Broussonetia papyrifera) n 562 Princess Tree (Paulownia tomentosa) n 565 Russian Olive (Elaeagnus angustifolia) n 568 Silk Tree (Albizia julibrissin) n 572 Strawberry Guava (Psidium cattleianum) n 576 Tamarisk (Tamarix chinensis T. ramosissima, T. parviflora, and T. gallica) n 579 Tree of Heaven (Ailanthus altissima) n 585 Velvet Tree (Miconia calvescens) n 589 Vines Chocolate Vine (Akebia quinata) n 594 Climbing Ferns (Lygodium japonicum and Lygodium microphyllum) n 597 English Ivy (Hedera helix) n 602 Field Bindweed (Convolvulus arvensis) n 606 Japanese Dodder (Cuscuta japonica) n 610 Japanese Honeysuckle (Lonicera japonica) n 614 Japanese Hops (Humulus japonicus) n 618 Kudzu (Pueraria montana) n 622 Mile-A-Minute (Persicaria perfoliata) n 626 Oriental Bittersweet (Celastrus orbiculatus) n 629 Porcelainberry (Ampelopsis glandulosa var. brevipedunculata) n 633 Swallow-Worts (Cynanchum rossicum and Cynanchum louiseae) n 636 Winter Creeper (Euonymus fortunei) n 640 Wisteria (Wisteria sinensis and Wisteria floribunda) n 644 Tables and Lists about Invasive Plants Common Names and Scientific Names n 649 State-by-State Designations of Invasive or Noxious Weeds n 665

xii n CONTENTS

Pathways of Introduction for Plants n 673 Impacts of Invasive Plants n 678 Major Organizations and Publications Concerned about Invasive Plants n 687 Plant Species Listed as Invasive or Noxious by Organizations and State and Federal Governments n 689 Set Appendices Appendix A: American Species That Are Invasive Abroad n 695 Appendix B: Major Federal Legislation and Agreements Pertaining to Invasive Species n 699 Appendix C: Selected International Agreements and Conventions Pertaining to Invasive Species n 707 Appendix D: ISSG’s 100 of the World’s Worst Invasive Alien Species n 710 Glossary n 713 General Bibliography: Selected Classic and Contemporary Works and Major Internet Data Sources n 723 Index n 727

n Preface Invasive species have gained our attention in different ways. Susan Woodward, who wrote about invasive microorganisms, fungi, and animals in Volume 1, had her interest in invasive animals first sparked as a student of biogeography in the 1970s. Birds such as the European Starling and House Sparrow were featured in textbooks to demonstrate how animals spread in an environment that was new to them or how quickly they evolved adaptations to varying local conditions across a whole continent. Graeme Caughley’s work on irruptions of red deer in New Zealand was new, and the modeling of invasions and management of exotics in their infancy. As a doctoral student at UCLA, she studied feral burros along the lower Colorado River, viewing them as an example of humans “changing the face of the earth” (the buzzwords of those days) by transporting domesticated and wild animals around the world. Under contract to the Bureau of Land Management (BLM) at that time, she collected baseline data on population dynamics, diet, home range size, and other aspects of burro behavior and ecology that would help that agency devise policies and practices for the animals’ management. With an applied aspect to her work, she straddled what has become two main perspectives on invasive species in general: an academic interest in the science of invasions and a management interest in preventing arrivals, eradicating or controlling the spread of those species that were able to establish populations, and managing those whose numbers and distribution were for all practical purposes already beyond eradication. Joyce Quinn, a biogeographer whose research dealt with distribution of plants and their relationships with the natural environment, such as climate and soils, wrote the invasive plants section in Volume 2. In spite of her experience, she found that researching and writing this book led her to learn more. Some plants that she had thought were an integral part of the “natural” landscape, such as common mullein, are actually alien plants that had become naturalized and are now widespread in the United States. She notes: Several years ago, an uninvited plant sprouted unexpectedly in my yard. I tried for years to get rid of it, dutifully pulling off the little sprouts as they emerged. After four or five years, I gave up and decided to let the plant grow. In a couple of years, it became an attractive tree about 10 ft. (3 m) tall. It had smooth speckled bark, long lacy compound leaves, and clusters of small purple star-shaped flowers. As I was doing research for this Encyclopedia, I discovered that my new plant was a chinaberry tree. While attractive, it had few redeeming qualities so I decided to eliminate it. A friend helped me saw the trunk, about 8 in. (20 cm) in diameter, slightly below ground level. I immediately poured undiluted glyphosate on the freshly cut stump, thinking that was the end of it. I paid no attention until four months later when I saw a 6 in. (15 cm) sprout! I sprayed it with herbicides, but another sprout soon emerged. I sprayed again, but at the time of this writing, I still do not know if I have managed to kill the invader. I fear that it will be an on-going process. If I have had such trouble with just one alien invasive plant, the challenges that land managers, conservationists, and agriculturalists have in battling invasive species seem insurmountable.

xiv n PREFACE

Scope The purpose of the Encyclopedia of Invasive Species is to provide an introduction to the species, issues, and management options involved with invasive animals, fungi, microorganisms, and plants. The number of plants and animals introduced into the United States is staggering. Only a relatively few establish self-sustaining populations, and very few of these actually become invasive (in the scientific sense of greatly and rapidly expanding their range in the United States). Still, there are hundreds of invasive species—too many to be included in a reference book of this sort. For many species, much remains to be learned, and it is premature to develop full entries for them, but this still leaves many to choose from. In selecting the 168 species for inclusion in the Encyclopedia, we have tried to offer a wide spectrum of invasive species that includes some present in the United States from colonial times, and some that have just been detected; some that completed their spread across the country long ago, and others that are in the midst of rapid population growth and range expansion. We also wanted to include some species that are found throughout the country, and some that are limited to a region or single state. For animals, we aimed to include representatives from all major classes of vertebrates and a good variety of invertebrates. The reader will find common, well-known invaders and others that may be a surprise. We also wanted to showcase a few fungi, especially those that have been major transformers of urban, suburban, and natural forests, and at least acknowledge the presence of invading microorganisms with a tiny sample of those threatening the health of native animals and, in some cases, humans as well. Finally, we wished to have a geographically broad selection of invasive animals, with all 50 states and Puerto Rico having some members of their nonindigenous fauna represented. Florida, Hawai’i, and California have the largest numbers of officially recognized invasive species. Residents of these states will undoubtedly find nonnative organisms causing significant impact in natural and artificial ecosystems missing from our accounts. This was necessary in order to include some organisms limited to other states. For plants, we also tried to include a little bit of everything. Volume 2 addresses a variety of growth forms, ranging from aquatic plants to trees and vines, and all regions of the United States. Some plants are widespread throughout the country, while others are localized. Many plants were deliberately brought to the United States as ornamentals or for some useful characteristic, while others were accidentally introduced. The length of entries dedicated to each species is variable. The taxonomic relationships of some plants and similar species are not always clearly defined. Some plants, for example, hybridize so freely that it becomes difficult to distinguish different species. A few accounts of invasive plants treat two or more related species in the same entry because their effects and management are similar. As with animals, we could always find “one more” species that should be included, but it was not possible to include all. A wealth of information from various sources can be accessed by the reader wanting to know more. The General Bibliography at the end of Volume 2 has a list of recommended resources, including websites. The Encyclopedia is specifically meant for high school and college students, but addresses many of the informational needs of the curious naturalist, horticulturalist, or any homeowner or environmentally concerned citizen who is interested in the origins and consequences of invasive plants and animals. Although some invasive species have been part of the landscape of the United States for literally hundreds of years, the wide-reaching effects of most are only beginning to become realized. Some invasive species are detrimental to native ecosystems and threaten biodiversity, others are more economically damaging to crops and livestock, and a few pose a danger to

PREFACE n xv

human health. Invasive species are a major part of current global environmental change. Experts consider them the second-greatest threat to native species after habitat destruction and fragmentation. The control and interdiction of invasive species coupled with the damage some incur on crops, pastures, livestock, native ecosystems, and human health and wellbeing costs billions of dollars each year. The invasive species problem is dynamic—as those in the Mid-Atlantic states weathering their first onslaught of the brown marmorated stink bug know well—and endlessly fascinating.

How to Use the Encyclopedia Volume 1 begins with an introduction to inform the reader of the nature and scope of issues related to invasive species in the United States. Separate sections deal with the terminology related to invasive species, the invasion process from an ecological point of view, the pathways by which nonnative species have been and continue to be introduced to the United States, some of the ecological and economic impacts of invasives, and a brief outline of the history of modern invasion science. A final section of the introduction describes the human factors that determine what species come in, where they succeed, and if and how they are managed. The introduction is followed by 88 entries describing microorganisms, fungi, invertebrates, and vertebrates. Entries are arranged alphabetically within major taxonomic groups. The species described represent the large number introduced and invasive in the continental United States, Hawai’i, and Puerto Rico. Each entry in both volumes includes the following elements, unless noted otherwise: Native Range Distribution in the United States Description Related or Similar Species Introduction History Habitat Diet (animals only) Life History (animals, fungi, and microorganisms only) Reproduction and Dispersal (plants only) Impacts Management Selected References Additionally, each entry in both volumes is accompanied by at least one photograph and maps that show the original and invasive range of the species in question according to the best information available. Often range maps are, by necessity, approximate. This is especially true for organisms not native to the United States or Europe, where biological surveys are more complete than on other continents. In Volume 1, the entries are followed by a list of state-by-state occurrences of invasive animals, fungi, and microorganisms; a glossary; and an index to both volumes. Volume 2 begins with a brief overview of invasive plants in the United States, which loosely follows the organization within species accounts, describing in general the scope of

xvi n PREFACE the invasive plant problem, including the ways, both intentional and accidental, that plants were brought into the country; and some of the effects invasive plants have on native plant and animal species, natural ecosystems, agricultural or fishing industries, recreational activities, or human health. The ways in which invasive plants reproduce and expand their range is summarized, as is information on management and prevention of invasive plants species. A sidebar on herbicides accompanies the overview. The 80 entries on invasive plants are arranged by growth form categories: aquatics, forbs, graminoids, shrubs, trees, and vines. Photographs of each species show different parts of the plant. Interesting facets of a plant’s use or history or of strategies attempted for its control are related in sidebars. Several supplementary lists follow the invasive plant entries to provide background information, and various tables summarize plant data in different, easily accessible ways, including a table of common and scientific names of both plants and animals briefly mentioned in the text of Volume 2, and a list of organizations concerned with invasive plants in the United States. Two tables of noxious or invasive plants, one organized by state and the other by species, as well as a table of species listed by type of impact are also available. Volume 2 concludes the set with these appendices to the Encyclopedia: a list of American species that are invasive in other parts of the world; a list of federal laws related to the prevention and management of invasive species; international agreements and conventions dealing with invasive species; and the IUCN/SCC Invasive Species Specialist Group’s list of 100 of the “World’s Worst Invasive Alien Species,” with an indication of those covered in the Encyclopedia. The glossary, a selected bibliography of classic and contemporary writings and online information sources, and the index to the set complete Volume 2. It is our hope that our efforts will stimulate thought and make the natural world more accessible to the general public. Informed readers can help make the decisions that will curtail the spread of species that have only recently arrived, prevent the arrival of yet others, and manage those that are currently invasive

Acknowledgments Both authors thank the photographers who graciously allowed their photos to be used, often donating them, or sometimes providing them at a reduced fee. They deserve our special thanks for giving life to the species descriptions. Bugwood.org and its associated personnel at the Center for Invasive Species and Ecosystem Health, University of Georgia, deserves special mention as a clearinghouse for providing informational sources and photographs. Joyce Quinn prepared the excellent maps for the species accounts. Each author is most appreciative of the other’s contributions to the development of the project, the overall organization of the volumes, and constructive critiques of text and illustrations throughout the manuscript preparation process. We complement each other and work well as a team. We acknowledge Kevin Downing, originally of Greenwood Press and now serving the broader ABC-CLIO community as editorial operations manager, who initiated the proposal for the Encyclopedia set, and David Paige of ABC-CLIO, who guided us through subsequent discussions and organizational details. Anne Thompson, development editor, later offered guidance in the specifics of the manuscript, and Erin Ryan helped with the specifications for the illustrations. We thank all four for creating a positive and flexible working environment and offering valuable suggestions all along the way.

n Invasive Plants in the United States: A Brief Overview

Although alien invasive plants in the United States come from many regions of the world, many of them originated in Eurasia, probably because of the long-term connection the United States has had with European immigrants. The United States has had trade and immigration from China, Japan, and other eastern Asian countries for more than 100 years, and some of the alien species native to Asia may have first been introduced to Europe. Few, if any, places in the United States have been left unaffected by alien invasive plants. Because of its relatively remote location and extreme climate, Alaska probably has the fewest. In contrast, the tropical island environment of Hawai’i is most vulnerable to introduced plants. Island ecosystems developed independently, without controlling factors such as mammalian herbivores and predators, so invaders can be especially destructive. Different growth forms are likely to be invasive in different climates or environments. Grass and drought-tolerant shrub species present the biggest problems in the arid west, while moisture-loving vines, trees, and shrubs gain a foothold in the humid eastern states. Although some species are noxious weeds or invasive throughout the entire country, other plants can be safely grown as a garden ornamental in climates less suited to them.

Arrival of Alien Plants in the United States Plant introductions may be either intentional or unintentional. Many of the invasive plants plaguing the United States were first brought to the country as ornamentals, some as early as the 1600s, some as late as the 1990s. It is understandable that early immigrants from Europe and other world regions would want a remembrance of their homeland in their gardens. We might offer them forgiveness, because they were unaware of how their favorite plants would behave in a new setting without natural enemies or competition to keep them in check. Other plants were brought to this country because they were important in household use, such as for natural dyes or as medicine. Although modern society may sneer at the supposed medicinal properties of “weeds,” we should remember that early settlers could not run down to the local pharmacy to purchase relief or a cure for a malady. Some plants actually are effective, some not. Some plants, such as kudzu, were encouraged for use by federal agencies, such as the Soil Conservation Service, as beneficial for erosion control, or as fast-growing forage, such as Johnsongrass, for livestock. Widespread erosion during the Depression in the 1930s saw widespread use of exotic plants to reclaim overused or damaged land. U.S. government agencies were unaware at the time of the potentially devastating effects of many of the species they were recommending. Accidental introductions may be caused by ignorance, carelessness, or just poor luck. Seeds may adhere to clothing or shoes and then be transported long distances across expanses that would otherwise be barriers to plant migration. Seeds or plant pieces are small enough to be overlooked when they arrive mixed into an otherwise-nondescript shipment of

xviii n INVASIVE PLANTS IN THE UNITED STATES grain or crop seeds. Sand, soil, or water used as ship’s ballast, which is then dumped at U.S. ports, may carry seeds or pieces of unwanted plants.

Realization of the Problem The science of ecology is relatively new, and many plant relationships were largely unknown in the United States until the years leading up to the first Earth Day in 1970, one of the events that triggered the rise of the environmental movement. It is now realized by many individuals and many federal and state agencies that alien species without their natural controls can have disastrous consequences. The proliferation of organizations and state agencies that classify plants as “noxious” or “invasive” or “prohibited” attest to the increased awareness of problems associated with introduced species. Biological controls, meaning insects or pathogens that attack alien invasive plants, are investigated thoroughly to assure that they do not detrimentally affect related native species or economically important crops. Declarations and agricultural screenings at airports and other ports of entry into the United States attempt to eliminate or at least limit the accidental movement of alien plant species into U.S. territory.

Impacts of Alien Invasive Plants Invasive plants not only damage the unique natural environments of the United States, they also have economic impacts. Alien plants often outcompete native plants for resources, such as light, water, soil nutrients, or even space. By reducing or eliminating native plants, they indirectly affect animals that depend on those plants. The result is a reduction in biodiversity and the creation of simpler ecosystems that are more susceptible to disturbances. The United States then loses the natural heritage of a varied landscape and, often, its unique plants or animals. Invasive plants have a detrimental economic impact. By encroaching on or taking over croplands, they reduce crop yields. As alternate hosts, they may introduce diseases or insects into agricultural areas. Many invasive plants are prickly or otherwise undesirable and hinder recreational activities, such as hiking, boating, swimming, or fishing. Farmers, ranchers, and park management agencies spend millions of dollars in attempts to eradicate or merely control or limit the spread of invasive plants.

Reproduction and Dispersal of Alien Invasive Plants Like native plants, invasives reproduce and spread either by seed or by sprouting from vegetative parts. Seeds may be distributed in several ways, including wind, water, animals, and human activities. Plant pieces are also either deliberately spread, such as when gardeners share their extras, or accidentally, such as when carried in a boat trailer to another water system. Invasive plants usually do not restrict themselves to the type of habitat they occupied in their native range. They are usually not invasive in the region where they originated because competition from other plants, or some other factor such as an insect predator, keeps them under control. In the absence of competition or a natural enemy in its introduced territory in the United States, invasive plants may extend to a wider range of environments.

INVASIVE PLANTS IN THE UNITED STATES n xix

Management Options No simple solution exists. The problem of eradicating or controlling alien invasive species is as complex as the array of invaders themselves. The ideal management is to avoid the problem altogether—to not deliberately plant an invasive species in one’s garden, and to eliminate what species are already there. This is not always practical or even possible. Cutting down the tree in your yard will do little to control the invasive species if 20 or more trees grow in the adjacent woods. The second-best approach is to reduce or eliminate the plant’s potential spread by preventing seed production or transportation of plant pieces that may sprout. Some plants respond to physical controls, such as pulling or digging, cutting, mowing, or grazing. Others require applications of chemical substances, herbicides, which either kill existing plants or prevent seeds from germinating. A more “natural” way to subdue invasive plant species is to unleash insect predators or pathogens that harm or control the plants in some way. Each method has drawbacks. Physical control is usually labor intensive and time consuming. Chemicals may cause harm to desirable plants or animals and threaten the natural environment. Unless thoroughly researched, imported biological controls can themselves become invasive pests. Whatever method is used, it all costs money and takes time. Management goals—containment, reduction, or eradication—should be realistic for the situation. While it may not be possible, either physically or monetarily, to totally eradicate an infestation of an invasive plant, it may be feasible to contain it or to reduce its dominance. The most basic goal is containment, which means preventing an invasive species from spreading to new areas, perhaps by physically erecting a barrier or preventing seed production. Reduction refers to reducing the amount of area infested by the weed or reducing its dominance. Total eradication, or completely eliminating the invader, may only be possible with small stands or new infestations.

What Can We Do? Everyone seems to have a different definition of what constitutes “alien and invasive,” and the concept of invasive species just has not reached the public. Some state and federal agencies still recommend and distribute invasive plant species for various “beneficial” purposes. Several blogs on the Internet tout the benefits of growing attractive alien plants in private gardens, stating that they do not care if the plant is invasive elsewhere. One blogger even professed liking the way the plant looked along roadsides. Although some individuals will demand to retain their “right” to grow the plants they want, many more citizens will be willing to do the right thing if they only know about the consequences posed by invasive species. The issue here is ignorance, not as a pejorative term, but as meaning unaware. Many states and municipalities now have educational programs to inform citizens of problems associated with alien species. Billboards urge boaters to clean their boats and trailers so that they do not carry invasive aquatic plants to pristine water bodies. Signs are posted at trailheads in state parks urging hikers to clean their boots before leaving or entering a trail, so as to not unwittingly disperse seeds. Native plant societies urge gardeners to avoid alien invasive plants and to plant native species compatible with their climate. Although many invasive species have a hold in the United States that is too strong or entrenched to ever be eradicated, newly invasive species can be controlled or eliminated if the public is aware of the consequences of some imported plants. Those portof-entry screenings are much less of an inconvenience than the potential devastation caused by an invasive species slipping through.

xx n INVASIVE PLANTS IN THE UNITED STATES

Herbicides

H

erbicides are a complicated lot, with several active ingredients sold under many different brand names. Major categories include preemergent or postemergent, contact or systemic, and nonselective or selective. Each active ingredient, meaning the substance that kills the plants, has a specific chemical structure that affects plants differently. Some may damage or kill the plant by interfering in some way with plant growth, including but not limited to restricting root growth, inhibiting cell division, or blocking photosynthesis. Depending on the herbicide and how it works, it may be applied as a foliar spray, to the basal bark, to the cut stump, or into slashes cut through the bark. Some herbicides may be toxic to mammals, fish, or birds, and skin contact may be harmful to some humans. Others may contaminate either groundwater or surface water and harm amphibians. Depending on the plant targeted, herbicides are mixed to different strengths. Many factors influence the proper selection and use of herbicides.

Types of Herbicides Preemergent herbicides are also called residuals because they remain in the soil. They prevent seeds of both annuals and perennials from germinating, and also sometimes affect shoots sprouting from perennial roots. Although some may target specific weeds, other preemergents are nonselective, preventing the germination of seeds of all types of plants. Postemergent herbicides are used on plants that have grown past the seedling stage. Contact herbicides are fast-acting and kill the parts of the plant that the chemicals touch. They are usually ineffective for perennials because they do not affect root growth, and are best used on annuals. Systemic herbicides are absorbed into the tissue of the plant and moved to other locations, such as the roots. Results are slower, but the entire plant is killed, making systemics a good choice for perennials. Nonselective herbicides affect any type of plant. The most common two categories of selective herbicides are those that target only broadleaf plants, and those that target only graminoids. Herbicides selective to broadleaf plants, therefore, can be used without harm in grasslands, and those selective to graminoids may be used to eradicate grasses without harm to broadleaf vegetation.

Application Methods Herbicides may be applied to the foliage, usually by spraying. A surfactant, a substance added to the spray, is sometimes needed to make the herbicide better adhere to the leaves, especially if the leaf cuticle is waxy or otherwise impermeable. Foliar sprays can be either contact or systemic. In some species, herbicides may be absorbed into the plant through the bark rather than through the foliage. This method may be applicable if spraying the canopy may harm nontarget vegetation. Different herbicides have different effectiveness in basal bark application. Cutting the trunks or stems close to ground level, then painting the cut stump with herbicide, is another method that may avoid damaging other plants. It also requires less product. Hack-and-squirt involves cutting slashes through the bark directly into the xylem of the plant, usually on a trunk or thick stem. Herbicides are then injected directly into the wounds.

INVASIVE PLANTS IN THE UNITED STATES n xxi

Regardless of what method or what type of herbicide is used, the timing of application is important. Although each species reacts somewhat differently, some generalizations can be made. Herbicides are frequently most effective when seeds are being produced, to prevent seed development. Biennial plants are generally easier to kill in the first season, when they are in an early stage of growth. Systemic herbicides must be applied when the plants are healthy and actively growing and translocating sugars to the roots. They are less effective during times of cold or drought when plants are stressed.

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n Alphabetical List of Invasive Plants Entries

Entries in the encyclopedia are arranged by growth form categories. Following are the invasive plant entries in alphabetic order. Asiatic Colubrina (Colubrina asiatica) Asiatic Sand Sedge (Carex kobomugi) Australian Pine (Casuarina equisetifolia) Brazilian Peppertree (Schinus terebinthifolius) Brooms (Cytisus scoparius, Spartium junceum, Genista monspessulana, and Cytisus striatus) Buffelgrass (Pennisetum ciliare) Canada Thistle (Cirsium arvense) Carrotwood (Cupaniopsis anacardioides) Cheatgrass (Bromus tectorum) Chinaberry (Melia azedarach) Chinese Lespedeza (Lespedeza cuneata) Chocolate Vine (Akebia quinata) Climbing Ferns (Lygodium japonicum and Lygodium microphyllum) Cogongrass (Imperata cylindrica) Common Mullein (Verbascum thapsus) Common Reed (Phragmites australis ssp. australis) Common St. Johnswort (Hypericum perforatum) Cordgrasses and Their Hybrids (Spartina alterniflora, Spartina densiflora, Spartina patens, Spartina anglica, and Spartina alterniflora x foliosa) Crimson Fountain Grass (Pennisetum setaceum) Dyer’s Woad (Isatis tinctoria) English Ivy (Hedera helix) Eurasian Watermilfoil (Myriophyllum spicatum) Exotic Bush Honeysuckles (Lonicera maackii, Lonicera morrowii, Lonicera tatarica, and Lonicera x bella) Field Bindweed (Convolvulus arvensis) Fig Buttercup (Ficaria verna) Fire Tree (Morella faya) Garlic Mustard (Alliaria petiolata) Giant Hogweed (Heracleum mantegazzianum)

xxiv n ALPHABETICAL LIST OF INVASIVE PLANTS ENTRIES Giant Reed (Arundo donax) Giant Salvinia (Salvinia molesta) Gorse (Ulex europaeus) Goutweed (Aegopodium podagraria) Halogeton (Halogeton glomeratus) Hydrilla (Hydrilla verticillata) Ice Plant and Crystalline Ice Plant (Carpobrotus edulis and Mesembryanthemum crystallinum) Japanese Barberry (Berberis thunbergii) Japanese Dodder (Cuscuta japonica) Japanese Honeysuckle (Lonicera japonica) Japanese Hops (Humulus japonicus) Japanese Knotweed (Fallopia japonica) Japanese Stilt Grass (Microstegium vimineum) Johnsongrass (Sorghum halepense) Jubata Grass and Pampas Grass (Cortaderia jubata and Cortaderia selloana) Kahili Ginger (Hedychium gardnerianum) Kikuyugrass (Pennisetum clandestinum) Koster’s Curse (Clidemia hirta) Kudzu (Pueraria montana) Lantana (Lantana camara) Leafy Spurge (Euphorbia esula) Medusahead (Taeniatherum caput-medusae) Melaleuca (Melaleuca quinquenervia) Mile-A-Minute (Persicaria perfoliata) Multiflora Rose (Rosa multiflora) Musk Thistle (Carduus nutans) Oriental Bittersweet (Celastrus orbiculatus) Paper Mulberry (Broussonetia papyrifera) Perennial Pepperweed and Hoary Cress (Lepidium latifolium and Cardaria draba) Porcelainberry (Ampelopsis glandulosa var. brevipedunculata) Prickly Russian Thistle (Salsola tragus) Princess Tree (Paulownia tomentosa) Purple Loosestrife (Lythrum salicaria) Quackgrass (Elymus repens) Rattlebox (Sesbania punicea) Russian Olive (Elaeagnus angustifolia) Silk Tree (Albizia julibrissin) Spotted Knapweed (Centaurea stoebe) Strawberry Guava (Psidium cattleianum)

ALPHABETICAL LIST OF INVASIVE PLANTS ENTRIES n xxv

Swallow-Worts (Cynanchum rossicum and Cynanchum louiseae) Tamarisk (Tamarix chinensis, Tamarix ramosissima, Tamarix parviflora, and Tamarix gallica) Toadflax (Linaria dalmatica ssp. dalmatica and Linaria vulgaris) Tree of Heaven (Ailanthus altissima) Tropical Soda Apple (Solanum viarum) Velvet Tree (Miconia calvescens) Water Chestnut (Trapa natans) Waterhyacinth (Eichhornia crassipes) West Indian Marsh Grass (Hymenachne amplexicaulis) Winter Creeper (Euonymus fortunei) Wisteria (Wisteria sinensis and Wisteria floribunda) Yellow Himalayan Raspberry (Rubus ellipticus) Yellow Starthistle (Centaurea solstitialis)

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n Aquatic Plants n Eurasian Watermilfoil Also known as: Spike watermilfoil Scientific name: Myriophyllum spicatum Synonyms: None Family: Watermilfoil (Haloragaceae) Native Range. Widely distributed in Europe, Asia, and North Africa. Distribution in the United States. Found in every state except Wyoming and Hawai’i. A major problem in the Northeast, Upper Midwest, Gulf Coast drainages, Southwest river systems, and the Pacific Northwest, it is still expanding its range. Description. Eurasian watermilfoil is an herbaceous aquatic perennial that is submersed, meaning it grows primarily under the water surface. It usually grows in water depths of 3–13 ft. (1–4 m), but can be rooted on bottom sediments as deep as 33 ft. (10 m) beneath the surface. The species is variable in appearance. The slender, hairless stems have no leaves toward the base due to lack of light. Growing stem tips are often reddish brown. Upon reaching the water surface, plant stems branch and form a dense canopy. Plants also branch when they are cut, browsed or otherwise damaged. In shallow water, stem densities can exceed 30 per sq. ft. (300/m2). Olive-green leaves, 4–5 per node, are whorled around the stem. Each leaf is finely divided into narrow segments or leaflets, usually 12–16 pairs, but sometimes as few as 5 or as many as 24. The soft, feathery leaflets are 0.5 in. (1.3 cm) long. When removed from the water, leaflets become limp and cling to the stem above the node. With cooler fall temperatures, stems die back to the propagating root crowns and plants overwinter rooted in bottom sediment. In warmer areas, plants can continue growing throughout the winter months. Carbohydrate storage is in the shoots and roots, and plants do not grow turions. Growth begins rapidly when spring temperatures near 59ºF (15ºC). Roots are fibrous and often become fragmented. Beginning in early summer and continuing for several months, flowers develop on reddish spikes that extend 2–4 in (5–10 cm) out of the water. Stems beneath the spikes become thickened and curved to lie parallel with the surface. Small yellow or pinkish, four-part flowers occur in whorls of four (rarely five) around the inflorescence, with female flowers at the base and male flowers at the top. After pollination, flower spikes sink down into the water. Four small hard capsules, 0.05–0.1in (1–3 mm), develop from each flower. When flowering is complete, stems fragment, growing roots at the nodes before breaking away. If conditions are not suitable, or stems and leaves are eaten by herbivores, plants may not reach the surface and flower. Related or Similar Species. Ten species of Myriophyllum are native to the eastern United States, but taxonomy is unclear, causing confusion in identification. The number of leaf divisions, 5–24 pairs, is usually sufficient to distinguish Eurasian watermilfoil from other species. The most closely related species native to North America is northern watermilfoil, also known as shortspike watermilfoil, with 5–10 leaflet pairs that remain rigid when removed from water. The stem beneath the flower spikes of the northern watermilfoil is straight and not thickened.

322 n AQUATIC PLANTS Northern watermilfoil forms blackish-green turions, or scaly shoots from underwater buds, whereas the Eurasian species does not. Parrotfeather, native to the Amazon River in South America, is commonly used in aquariums and garden ponds. Although it is less pervasive than Eurasian watermilfoil, it forms denser stands which provide more breeding habitat for mosquitos. Leaves, in whorls of 4–6, occur in two types, submersed and emergent. Submersed leaves, with 20–30 leaf divisions, are most commonly confused with Eurasian watermilfoil. The emergent leaves have only 6–18 divisions, and are bright green. The most distinctive difference is that the emergent leaves and stems grow as much as 1 ft. (0.3 m) up out of the water. This plant causes problems similar to those of Eurasian watermilfoil, and is a noxious weed in several states. Although native to the southern United States and endangered in Kentucky, Ohio, and After its initial introduction to the Eastern Seaboard, Eurasian Pennsylvania, variable waterwatermilfoil spread rapidly throughout the Northeast, into the milfoil is an invasive species in Tennessee River valley, and into the Pacific Northwest. (Native range some New England states. It adapted from USDA GRIN and selected references. Introduced range has two types of leaves. The adapted from USGS Nonindigenous Aquatic Species Database and whorled leaves below the water selected references.) surface are reddish-green to brown, very finely dissected or threadlike, and 0.5–2.5 in. (1.4–6.4 cm) long. Emergent leaves, which grow on stalks rising 6–8 in. (15–20 cm) out of the water, are small, 0.25 in. (0.6 cm) and oval. The native coontail, also called common hornwort, differs from Myriophyllum species in that it is a floating plant that does not root. Its toothed leaves, making it feel rough to touch, are bright green, stiff, and brittle. The whorled leaves, which curve upward to resemble a tail, remain rigid when removed from water. It is not invasive and is an important part of natural ecosystems. Introduction History. The introduction of Eurasian watermilfoil to North America is not clear. It may have been accidentally introduced into the northeastern United States sometime between the late 1800s and 1940, perhaps in ship ballast in the late 1800s. Reports

EURASIAN WATERMILFOIL n 323

A. Finely divided leaves are whorled around the stem. (Chris Evans, River to River CWMA, Bugwood.org.) B. Leaflets cling to the stem when the plant is out of the water. (Richard Old, XID Services, Inc., Bugwood.org.) C. Tiny flowers are whorled around the flower spikes. (Leslie J. Mehrhoff, Ecology and Evolutionary Biology University of Connecticut, Bugwood.org.)

prior to 1940, however, may be due to misidentified plants. The first recorded collection was in Washington, D.C., in fall 1942. By 1985, it had spread to 33 states and adjacent parts of Canada. Plants may have been intentionally introduced to the Tennessee Valley Authority (TVA) system in 1953 by a resort owner, and some anglers have deliberately stocked lakes or ponds. Some Oklahoma populations developed when earthworm farmers used Eurasian watermilfoil for packing material. Long-distance dispersal can be attributed to the aquarium and water garden trade, through which it is still sold. Habitat. Eurasian watermilfoil tolerates a wide range of environmental conditions, from frozen ponds in Minnesota to shallow, warm bays in Florida. It primarily invades disturbed areas where native plants are unable to adapt to changes, and is less likely to spread into healthy ecosystems. Although it prefers quiet, stagnant water commonly found in ponds, lakes, reservoirs, pools, ditches, and irrigation canals, either deep or shallow, it also grows on muddy shores and in flowing water. Because it tolerates fresh to slightly brackish water, with salinity as high as 15 ppt, it is found in estuaries. It is also tolerant of many types of water pollution, as well as pH levels 5.4–11. Because it is herbaceous and protected by water, it survives in ice-covered lakes. It requires high light levels compared with other submersed plants, but grows rapidly over a broad temperature range. Reproduction and Dispersal. Although plants reproduce by seed, vegetative growth is responsible for its spread in North America. New plants, which grow from each stem node, will root in the muddy bottom. Stems become naturally broken apart by wind and waves, and by self-fragmentation after flowering. Boat traffic or weed cutting machines will also cut and spread fragments. Fragments are inadvertently carried on boats and trailers, and by currents downstream in river systems. Seedlings are rare. Seeds need temperatures higher than 57ºF (14ºC) to germinate, but amount of light is not important. Too much sediment, however, impedes germination. Impacts. Eurasian watermilfoil is considered the worst waterweed in the continental United States. Millions of dollars are spent nationwide in control. Several states, including Washington, Minnesota, Wisconsin, Vermont, and New York, spend approximately $1 million each year. Although no direct financial assessment exists, infestations of Eurasian watermilfoil negatively affect recreational use of water bodies, making boating, swimming, and fishing

324 n AQUATIC PLANTS unpleasant, if not impossible. Plant canopies in stagnant water provide ideal mosquito habitat. Dense stands of plants clog irrigation systems and intakes for hydropower. By growing rapidly and creating dense canopies on the water surface, Eurasian watermilfoil reduces light penetration early in the growing season, thereby shading out native plants, such as the native northern watermilfoil. Although the northern watermilfoil is able to successfully compete in aquarium tank studies, it fails to do so in the field. With decreased plant biodiversity, fewer animals, including benthic invertebrates and native fish, can survive. Fish have fewer spawning areas and do not grow as large. Decomposition of so much biomass at the end of summer changes water chemistry, increasing phosphorus and nitrogen levels. Eurasian watermilfoil also decreases the amount of oxygen beneath the mats, and raises both the temperature and pH of the water. Management. Thorough inspection and cleaning of boats and trailers may prevent fragments from being carried to noninfested water bodies. Several methods of control also have negative impacts on native plants, fish, and other wildlife. Mechanical harvesting and herbicides kill beneficial insects and may do more long-term harm. Mechanical harvesters, rototillers, and dredges are also expensive, labor intensive, and disruptive to the environment. Physical removal provides short-term control, while insect predation represents long-term control. Physical means of control are ineffective in the long term because broken pieces of Eurasian watermilfoil will grow into new plants. Small plants may be hand-pulled, but all pieces must be removed from the water. Mechanical harvesting can control growth in larger areas, but should be done more than once in a summer season. Harvesting implies that cut plants are removed and disposed of elsewhere. Rototilling the bottom pulls up the roots, which can then be removed. Water level manipulation may be practical in reservoirs, canals, or ditches, but not in natural areas. A higher water level may limit light to the plants, effectively shading them out. Lower water levels expose plants to dehydration in summer and freezing in winter. Drawdown of 6.5 ft. (2 m) in the Tennessee Valley Authority system in the Southeast effectively reduces populations. Light may also be reduced by planting vegetation on banks or erecting shade structures. Vertical screen barriers inserted to a water depth of 13 ft. (4 m) will confine the infestations and prevent plant fragments from moving into other parts of the water body, perhaps a way to keep docks or swimming areas free. Those types of areas may also be kept clean by covering the sediment with a light-blocking substance. Care must be taken with any attempt at chemical control because herbicides may also kill fish and nontarget aquatic plants, cause more algae growth, and contaminate the water supply. Not all herbicides are approved for use in all types of water bodies, and selection of product must take into account whether control is needed in a natural lake or a roadside ditch. Some herbicide applications will suppress growth for six weeks up to one year. Fluridone is selective for watermilfoil and other nonnative weeds and is not harmful to recreation activities or drinking-water supplies. One application controls weeds for the season. Also selective, triclopyr and 2,4-D afford excellent control and do not affect native aquatics. Other herbicides have also been found to be effective. Research on insects and pathogens for potential biological control has been conducted for 30 years. Over 20 insect species have been observed feeding on Eurasian watermilfoil in its native range, but few have been investigated seriously because they do not appear to be host specific. Several species, some native to North America and some accidentally introduced, are possibilities. Three small herbivores, a pyralid moth (Acentria ephemerella), the milfoil midge (Cricotopus myriophylli), and a weevil (Euhrychiopsis lecontei) have been associated with declines in populations of Eurasian watermilfoil in some lakes. The moth, native to Europe but now widespread from the East Coast west to Minnesota and Iowa, prefers

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Eurasian watermilfoil but does not feed on it exclusively. Each female lays 100–300 eggs, often with two generations per year. The larvae feed on the apical meristems, reducing plant growth, height, and biomass, and inhibiting canopy formation. The milfoil midge may have been accidentally introduced to North America because it prefers Eurasian watermilfoil over the native northern watermilfoil. It is now widely distributed in the northern states from the West Coast to New York, but only in areas that support Eurasian watermilfoil. Its larvae may reduce the plant’s biomass by boring into the stems. Although it may be present in many lakes, it is difficult to identify. The weevil, native to and widely distributed in North America, is a watermilfoil specialist. All life stages eat tips, stems, and leaves. Although it initially fed on native northern watermilfoil, the weevil now prefers the introduced Eurasian watermilfoil. This weevil is now available commercially, but needs shoreline habitat where adults overwinter. Development of shorelines with houses and other structures inhibits its establishment. Inconsistent results with insects may be caused by slight chemical differences, such as nitrogen content, in different populations of Eurasian watermilfoil, which in turn provide different nutritive value to feeding insects, altering their vigor. Similarly, waterfowl in Alabama eat a lot of Eurasian watermilfoil, but the same species avoid it in the Great Lakes region. Grass carp (see Volume 1, Vertebrates, Fish, Grass Carp) (Ctenopharyngodon idella), a fish, is used for control of several aquatic pest species. Grass carp, however, prefer other food and only eat Eurasian watermilfoil if nothing else is available. Their presence can also deplete desired plant biomass, limiting food and shelter for native fish, invertebrates, and waterfowl. Most states do not allow importation of grass carp. Two fungi, Mycoleptodiscus terrestris and Colletotrichum gloeosporioides, are possibilities.

Selected References Agricultural Research Service. “Foiling Watermilfoil.” Agricultural Research Magazine, 1999. Accessed at United States Department of Agriculture. http://www.ars.usda.gov/is/AR/archive/mar99/ foil0399.htm. Johnson, R. L., and B. Blossey. “Eurasian Watermilfoil.” In Biological Control of Invasive Plants in the Eastern United States, by R. Van Driesche et al. USDA Forest Service Publication FHTET-2002-04, Morgantown, WV, 2002. http://www.invasive.org/eastern/biocontrol/6EurasianMilfoil.html.

Successful Eradication of Eurasian Watermilfoil in Cayuga Lake

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urasian watermilfoil dominated the waters of Cayuga Lake, one of the Finger Lakes of upstate New York, to the exclusion of most other water plants until 1991 when large populations of the pyralid moth were discovered there. Ten years later, the biomass of Eurasian watermilfoil was only 10 percent of what it had been, with no canopy, resulting in long-term control and reversion to the natural ecosystem. Native plants have repopulated the lake, economic viability for recreation-based communities has resumed, and herbicide use has been reduced.

326 n AQUATIC PLANTS “Parrotfeather (Myriophyllum aquaticum).” Non-native Invasive Freshwater Plants, Department of Ecology, State of Washington, n.d. http://www.ecy.wa.gov/Programs/wq/plants/weeds/ aqua003.html. Ramey, Victor. “Eurasian water-milfoil, Myriophyllum spicatum.” Center for Aquatic and Invasive Plants, University of Florida, 2001. http://plants.ifas.ufl.edu/node/278. Rook, Earl J. S. “Ceratophyllum demersum, Common Hornwort.” 2002, 2004. http://www.rook.org/earl/ bwca/nature/aquatics/ceratophyllum.html. Rook, Earl J. S. “Myriophyllum heterophyllum, Two Leaf Milfoil.” 2002, 2004. http://www.rook.org/earl/ bwca/nature/aquatics/myriophyllumhet.html.

n Giant Salvinia Also known as: water velvet, salvinia, African pyle, aquarium watermoss, kariba weed, water fern, koi kandy, floating fern Scientific name: Salvinia molesta Synonyms: Salvinia auriculata Family: Floating Fern (Salviniaceae) Native Range. Coastal regions, as far as 125 mi. (200 km) inland, of southeastern Brazil in the states of Sao Paulo, Parana, Santa Catarina, and Rio Grande do Sul, and in northeastern Argentina. From 24º S to 32º S latitude. Distribution in the United States. Over 40 drainage basins, primarily along the Gulf Coast and Atlantic Coast, from Texas east to Florida, north to Virginia, and in New York State. Also in Arizona, California, Hawai’i, and Puerto Rico. It is still expanding its range. Description. Giant salvinia is a free-floating fern. Horizontal stems, or rhizomes, float just below the water surface. The stems produce three leaves at each node, two floating or emergent and one submergent. The oval or round floating leaves, green or yellow-green, are opposite each other on the surface. Young floating leaves are thin, 0.3–0.6 in. (8–15 mm) wide, and lie flat on the water surface. Leaf size varies with space and nutrient conditions, but leaves of mature plants are usually heart-shaped or oblong, 0.5–1.5 in. (1.3–3.8 cm) wide and sometimes as wide as 2.4 in. (6 cm) when unfolded. They may become brown at the edges as they age. The crowding of plants forces the leaves of older plants to fold in the center, creating chains of upright leaves extending out of the water. The upper surface of leaves is covered with rows of bristly hairs. Each hair stalk divides into four extensions that rejoin at the tips to form a cage that resembles an eggbeater. These structures can be seen with minor magnification, such as a hand lens. The hairs, giving plants a velvety appearance, are an air trap that provides buoyancy. Hairs on the upper leaf surface repel water, while the short, straight hairs on the lower leaf surface attract water, a combination that keeps the leaf properly oriented. Although possibly damaged in older leaves, the hairy structures are clearly visible on young leaves. Giant salvinia has no roots. The underwater structures that resemble roots are filamentous fronds or leaves. The third leaf growing from the surface node is highly divided into brown or whitish filaments, which dangle in the water. The filaments are covered with very short hairs. The length of the filaments, several inches, stabilizes the floating plants. Descending stalks among the root-like leaves hold chains of egg-shaped spore cases. Related or Similar Species. Several plants closely related to giant salvinia, called the Salvinia auriculata complex, include Salvinia auriculata, S. biloba, and S. herzogii. All have the same type of eggbeater hairs, but are difficult to identify. Although all are federal noxious weeds, none occur in the United States.

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Common salvinia, also known as water spangles, is an invasive aquatic species from Central and South America that closely resembles giant salvinia. It produces two round or oval floating leaves, 0.2–0.75 (0.4– 2.0 cm) long, from each rhizome node. Older leaves fold at the midrib and stand more erect. In shady locations, the leaves remain round and emerald green; leaves in full sun become larger, longer, and rusty brown. The third leaf from the node is the submerged filaments. Both the underside of the floating leaves and the filaments are covered with long hairs. The most distinguishing feature is that the hairs on the upper leaf surface are not joined at the tip, and therefore lack the eggbeater structures. Mat-forming waterfern plants native to the United States include three Azolla species, all of which have very small leaves. Mosquito fern, native to midwestern and eastern North America, is less than 0.5 in. (1.3 cm) wide, with First found growing in a natural water body in 1995, giant salvinia is a lacy-looking leaves. The gray- recent invader dispersed by the aquarium and water garden trades. green or rusty-red leaves fre- (Native range adapted from USDA GRIN and selected references. quently overlap, giving the plant Introduced range adapted from USGS Nonindigenous Aquatic Species a quilted look. It can form large Database and selected references.) mats, 1.5 in. (4 cm) thick, in stagnant water. Mexican water-fern, native to the midwestern and western United States, has tiny (1 mm), overlapping leaves. Each leaf has two lobes, one on the surface and one submerged. Pacific mosquitofern plants, native to the West Coast, are 0.4–0.8 in (1–2 cm) across, with green overlapping leaves, sometimes tinged with pink, orange, or red. Species of water clover, so called because their leaves are divided into four parts resembling clover, have leaves which are borne on long stalks either projecting out of the water or submerged. Introduction History. Giant salvinia was first recorded growing in a natural area in 1995, in a private pond in South Carolina, from which it has since been eradicated. It is believed to have been introduced via the aquarium and water garden trade, subsequently discarded into a waterway when the plants outgrew the aquarium or pond. Flooding may also have accidentally released the species from pond cultivation. The plant is still offered for sale in

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A. Floating plants can completely cover a lake. (Ted D. Center, USDA Agricultural Research Service, Bugwood.org.) B. Leaves are usually heart-shaped. (© Barry Rice, Sarracenia.com.) C. The upper surface of leaves is covered with bristly hairs. (© Barry Rice, Sarracenia.com.) D. Under crowded conditions, the leaves fold in the middle. (Troy Evans, Great Smoky Mountains National Park, Bugwood.org.) E. “Egg beater” cages on the leaf hairs. (© Barry Rice, Sarracenia.com.)

nurseries and mail-order suppliers in several states, and is frequently a contaminant in aquatic nursery plant stock. Common salvinia, which has been cultivated in gardens and greenhouses since the late 1880s, is still widely available for sale. It is also a common contaminant in other water plant stock. Habitat. Giant salvinia is found in quiet, nutrient-rich water, such as lakes or ponds, oxbows and backwater swamps, marshes, rice fields, ditches, and any slowly flowing water courses. Plants grow only in freshwater and are intolerant of as little as 11 ppt salt. Growing in tropical, subtropical, or warm temperate climates, the species can tolerate freezing air temperature but not ice formation in the water. Giant salvinia is capable of overwintering in mild, southern climates. Plants do best at water temperatures of 68–86ºF (20–30ºC), and dense mats do not develop at temperatures lower than 50ºF (10ºC). Exposure to 26.5ºF (−3ºC) or above 109ºF (43ºC) will kill buds in two hours’ time. Reproduction and Dispersal. Although giant salvinia has many spore cases, it is not known to be fertile, and its means of reproduction is strictly vegetative. Each rhizome node has as many as five buds that produce new rhizome branches, which radiate outward. Stress from cool temperatures or desiccation stimulates latent buds to sprout. Rhizome pieces are transported to other water bodies by boats, propellers, boat trailers, jet ski intakes, and other water gear. Young plants or pieces are carried downstream by currents or are distributed when ponds or lakes flood and overflow. Wind may also push floating plants to new locations within water bodies. The plant’s hairiness minimizes desiccation when it is transported out of the water. Impacts. The vegetative reproductive method of giant salvinia allows it to rapidly create a network of plants that grow into dense mats covering the water surface. Under ideal greenhouse conditions, it can double its numbers every 2–4 days. In one month, one plant can multiply to 8,000 plants, and to more than 67 million plants in two months. Under good conditions and warm weather, the size of a mat in a natural environment may double in 7–10 days. Vegetation mats may cover entire lakes or other water bodies. In other countries,

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Recuperation of Invasive Species?

A

fter the British Petroleum oil spill in the Gulf of Mexico in April, 2010, the governor of Louisiana ordered the Davis Pond Freshwater Diversion Project to be fully opened, an attempt to stem the inflow of oil by flooding the area with fresh water. The influx of so much fresh water lowered the salinity of the waterways and allowed freshwater invasive species to gain a foothold. Giant salvinia was one of the plants identified in November to be taking advantage of the lower salinity levels, and it is questionable whether the species can be eliminated in this new environment. Source: Bob Marshall, The Times-Picayune, “Freshwater areas’ next big battle has arrived.” November 21, 2010. www.nola.com/outdoors/index.ssf/2010/11/freshwater_areas)_next_big_ batt.html.

mats covering 96 sq. mi. (250 km2) and measuring 2–3 ft. (0.6–0.9 m) thick have been recorded, indicating its potential. One individual plant was documented to have increased to cover 40 sq. mi. (104 km2) in three months. Plants grow faster when water is saturated with nutrients, perhaps resulting from fertilizer runoff. Mats alter ecosystems by blocking light, which kills algae and other organisms that serve as food for fish and other species higher on the food chain. Plants alter the water quality, lower the pH level, and increase temperature and carbon dioxide content. Decaying vegetation uses oxygen, depleting the supply for fish, insects, and other aquatic organisms. At Enchanted Lake on O’ahu, Hawai’i, giant salvinia threatens nesting habitats of endangered waterbirds, including the Hawaiian Coot, Hawaiian Gallinule, and the Hawaiian Stilt. Although populations of giant salvinia have been reduced in that location, the plant continues to expand its range to other sites, including the big island of Hawai’i. Its rapid spread may threaten cultivated aquatic crops, such as rice. It clogs water lines carrying drinking water, irrigation canals, and intakes for hydroelectric power plants. The dense mats interfere with boating, fishing, and recreational activities or water sports. Common salvinia has escaped into natural areas by flooding or by intentional release, growing into dense mats in Texas and Louisiana, where it is a noxious weed. In Louisiana, it is documented to have covered a waterway 12 mi. (19.3 km) long and 360 ft. (110 m) wide as thickly as 8–10 in. (20–25 cm). It may displace native duckweed, which is an important food for waterfowl. It may also dominate native mosquito fern in summer. Management. New infestations of giant salvinia can be prevented by thorough washing of all boating and other equipment after leaving the water. Even one piece can start a new population. Although small infestations can be removed by hand, the species must be identified and removed quickly because the plant spreads rapidly. Other alien floating plants, such as waterhyacinth, however, may invade after giant salvinia is eradicated. Physical methods of removal, either by hand or by mechanical harvesters, are only feasible for small infestations that have not yet become established. All pieces should be bagged and disposed of in an upland landfill, not near water. Because giant salvinia does not tolerate salinity, infestations can be controlled by flooding with seawater. Although chemical applications may be effective, they require long-term contact. Repeated applications of fluridone, hexazinone, glyphosate, or diquat may control the plant.

330 n AQUATIC PLANTS Chemical control is further complicated because masses of decaying plants severely deplete the oxygen in the water. Because several insects feed on giant salvinia in its native Brazil, where it does not form dense mats, biological control is possible. Large populations, however, may also need herbicide applications. A host-specific weevil (Cyrtobagous salviniae) from giant salvinia’s native range in southeastern Brazil and adjacent countries has succeeded in suppressing populations in Australia, Asia, and Africa. This tiny insect, 0.1 in. (2.5 mm) long, lives in or on the leaves and submerged rhizomes. After the eggs hatch in a cavity chewed into the leaf bud by the female, the larvae eat the leaf bud base and tunnel into the rhizomes and petioles of the plant. Until temperatures drop below approximately 75ºF (24ºC), this weevil can generate a new generation every month. Populations can reach 30 adults and 90 larvae per sq. ft (300 adults and 900 larvae per m2) of water surface. Cyrtobagous salviniae is host-specific and will not eat North American native water plants, such as mosquito fern or water clover. In preliminary trials in Texas, using Cyrtobagous salviniae weevils collected from common salvinia plants in Florida, results were inconclusive because of other variables such as flood and drought, which affected the weevils. Confusion exists regarding the identity of those weevils, however, and it is believed that the weevils in the United States may be genetically distinct from the weevils that are very effective in other parts of the world. Release of Cyrtobagous salviniae imported from Australia is pending positive identification of the weevil species collected in the United States.

Selected References Jacono, C. C. “Common—Salvinia minima Identification.” U.S. Geological Survey, 2003. http:// salvinia.er.usgs.gov/html/identification1.html. Jacono, C. C. “Giant Salvinia—Salvinia molesta Identification.” U.S. Geological Survey, 2003. http:// salvinia.er.usgs.gov/html/identification.html. Julien, M. H. “Floating Fern (Salvinia).” In Biological Control of Invasive Plants in the Eastern United States, by R. Van Driesche et al. USDA Forest Service Publication FHTET-2002-04, Morgantown, WV, 2002. http://wiki.bugwood.org/Archive:BCIPEUS/Floating_Fern_(Salvinia). National Biological Information Infrastructure (NBII), Comite´ franc¸ais de l’UICN (IUCN French Committee), and IUCN SSC Invasive Species Specialist Group (ISSG) “Salvinia molesta (Aquatic Plant, Herb).” ISSG Global Invasive Species Database. 2005. http://www.issg.org/database/species/ ecology.asp?fr=1&si=569 “Salvinia Complex.” Plant Pest and Health Prevention Services (PHHPS). California Department of Food and Agriculture, n.d. http://www.cdfa.ca.gov/phpps/ipc/weedinfo/salvinia.htm.

Successful Biological Control

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yrtobagous salviniae weevils, from Brazil, were released in Australia in 1980. In only 14 months, they succeeded in eliminating 90 percent of giant salvinia from Lake Moondarra, which was previously almost completely covered with plants. This weevil destroyed more than 8,000 tons of the plant in less than a year. Source: Julien, M. H. 2002.

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n Hydrilla Also known as: water thyme, waterthyme, Florida elodea, Indian star vine Scientific name: Hydrilla verticillata Synonyms: None Family: Frog’s-bit (Hydrocharitaceae) Native Range. Probably from the warmer areas of southern Asia and India and Korea. Hydrilla is so widely spread throughout the world, on all continents except Antarctica, that its native range is difficult to determine. The dioecious form in the United States is native to India, while the monoecious form is native to Korea. Distribution in the United States. Most of the eastern half of the country. The Atlantic Coast and Gulf Coast states, from Maine south and west to Texas; north through Oklahoma, Arkansas, Missouri, Iowa, Wisconsin, and Upper Michigan, and east to Maine. Western states, including Colorado, Arizona, Nevada, California, Idaho, and Washington. Also in Puerto Rico. Most invasive in the southern and coastal states. The dioecious form is found in the southern states, while the monoecious form is found north of North Carolina. A population in Connecticut derived from the dioecious strain is expanding its range, with new populations being discovered in the northern and midwestern states. Description. Hydrilla is an herbaceous perennial that grows submersed in freshwater. Plants are most often rooted in bottom sediments, but broken pieces may be free-floating. Its appearance, such as number of leaves, length of stem, and leaf shape, is variable and dependent on age and environmental conditions. Slender stems growing up from the bottom may be 6.5 ft. (2 m) or more long, depending Two forms of hydrilla are in the United States, a dioecious form in the on the water depth. Some have warmer South and a monoecious form in cooler, northern climates. been measured at 30 ft. (9 m). (Native range approximated from selected references. Introduced range Stems of dioecious plants in adapted from USGS. Aquatic Species Database and selected references.)

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A. Plants may form dense floating mats. (David J. Moorhead, University of Georgia, Bugwood.org.) B. Narrow, pointed leaves are whorled around the stem. (Robert Vide´ki, Doronicum Kft., Bugwood.org.) C. Plant pieces entangled in boat motors may be dispersed to other water bodies. (Wilfredo Robles, Mississippi State University, Bugwood.org.) D. Small tubers can produce many new plants. (Robert Vide´ki, Doronicum Kft., Bugwood.org.)

deep water have few branches, but they branch profusely upon reaching the surface, forming dense vegetation mats. Monoecious plants, however, branch at the sediment rather than at the surface, sending a denser array of stems growing up through the water column. Small, 0.25–0.8 in (0.6–2 cm) long, narrow, pointed leaves, with finely toothed margins, grow in whorls of 3–10 along the stems. The lower surfaces of leaves on mature hydrilla sometimes have small sharp spines on the reddish midrib, making the plant feel scratchy. The green leaves are translucent when clean, but the top leaves, sun bleached or damaged by bacteria, may range from yellowish to brownish green. Leaf axils have pairs of tiny scales, only 0.5 mm long, with an orange-brown hairy fringe. Turions, which are condensed shoots 0.25 in. (0.6 cm) long with whorls of fleshy leaves, grow in leaf axils. Turions are dark green and look spiny. In cold climates, the stems and leaves die back seasonally, but the tubers and turions send up new stems in spring. Small, pale tubers, 0.2–0.5 in (0.5–1.3 cm), that resemble tiny potatoes develop at the ends of stolons or rhizomes, both on and below the surface of the bottom sediment where the plant is rooted. They may be as deep as 12 in. (30 cm) into the sediment. Tiny female flowers grow singly on long, 4 in. (10 cm), thread-like stalks from leaf axils near the top of the stems. Three whitish sepals enclose three transparent petals. The funnel-shaped flowers float upright on the surface, the petals keeping the flower centers dry. Tiny male flowers, also with three sepals and three petals, range in color from whitish, reddish, brownish, to greenish. Male flowers break loose from the leaf axils and float freely on the water surface, looking like tiny inverted bells. Pollination is by wind. Related or Similar Species. Hydrilla may be difficult to distinguish from the nonnative Brazilian waterweed, also called Brazilian elodea, or the native Canadian waterweed with which it often grows. Brazilian waterweed has 4–5 leaves on each whorl, and the fine serrations on the leaf margins are only detectible under magnification. Canadian waterweed has whorls of 3–6 leaves. Neither plant has tubers.

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Introduction History. An aquarium dealer shipped the dioecious variety of hydrilla plants from Sri Lanka to Florida in the 1950s. After being deemed unsatisfactory, the plants were dumped into a canal near Tampa Bay. In 1955, some of the plant population was taken to Miami for the pet trade, where careless or accidental release allowed it to infest many water bodies. By 1988, it had spread to 49,500 ac. (20,000 ha) of water bodies in Florida. The monoecious strain, from Korea, was first reported in Delaware in 1976 and in the Potomac River around 1980. Habitat. Other than a need to be submerged in freshwater, hydrilla has few specific requirements. It grows in still or slow-flowing water of various depths in tropical to temperate climates where water temperatures can be 50–95ºF (10–35ºC). Temperatures of 68–81ºF (20–27ºC) are optimal for photosynthesis, but hydrilla will continue to grow slowly at lower temperatures. It can grow in clear water with low nutrients, or in murky, nutrient-rich water. Although optimum pH is 7, hydrilla grows within a range of acidity. Plants are found in many types of water bodies, including lakes, ponds, reservoirs, springs, rivers, canals, ditches, tidal zones, and rice fields. It tolerates polluted water and has moderate tolerance for salinity, up to 7 percent, allowing it to infest the upper reaches of estuaries such as Chesapeake Bay. Because it can grow with little sunlight, it is able to colonize deeper water than most native aquatic plants. Reproduction and Dispersal. Hydrilla is one species with two forms, a monoecious and a dioecious biotype. The southern biotype is dioecious, with only female plants. Although they flower, they cannot set seed. The northern biotype is monoecious, with the male and female flowers on the same plant, but seeds are rare. The only known seed production in the United States is in monoecious stands in North Carolina. Seeds mature in September and sink to the bottom sediment, where they germinate the following spring. Although, the germination rate is less than 50 percent, new plants can flower after two months. Hydrilla reproduction is almost exclusively vegetative, from stem fragments, stolons, or rhizomes and turions. Even stem fragments that contain only 1–3 whorls of leaves can produce new plants. Tubers develop at the ends of rhizomes or stolons and then grow new plants. One tuber can produce up to 500 new tubers per sq. ft. (5,000 per m2). Tubers remain viable for several days out of water and for more than four years in sediment. Turions, produced in the leaf axils, are specialized buds. After detaching from the parent plant, they are dispersed by water currents to form new colonies. Floating segments produce more turions than do rooted stems. Both tubers and turions are overwintering organs in cold climates. Turions begin to grow when temperatures reach 64.5ºF (18ºC). Tubers and turions can also remain viable under ice cover, dry conditions, and herbicide application. The only method of dispersal to new water bodies is through human activities, such as boating and fishing or through the aquarium trade. Some California and Washington populations may have been transported as hitchhikers on water lily plants. Impacts. Masses of hydrilla stems just beneath the surface impede navigation and commercial activities and interfere with recreation. Plants clog irrigation canals, flood-control canals, and intake pumps for irrigation and for hydroelectric plants. Recreational activities, such as swimming, boating, and sport fishing, are curtailed by hydrilla mats. Stagnant water in dense mats is prime mosquito-breeding territory. Because plants initially grow from the bottom, infestations may go unseen until it is too late for efficient control. Because plants can grow in low light, only 1 percent of what is available, and in silty water, hydrilla begins growing during the short days of early spring before native plants begin to grow. Plants grow rapidly, up to 1 in. (2.5 cm) a day. Dense, branching mats block

334 n AQUATIC PLANTS light, displacing native aquatic plants such as pondweeds, tapegrass, and coon’s tail. They alter the community structure by changing the water chemistry, raising the pH, and increasing temperature. As the decay of the large biomass depletes oxygen in the water, zooplankton die and the fish population changes. Hydrilla even outcompetes two other nonnative aquatic pests, Eurasian watermilfoil (see Aquatic Plants, Eurasian Watermilfoil) and Brazilian waterweed. Fish, especially chain pickerel, congregate under or near mats, where they use the cover for hunting. The economic impact is tremendous. The most abundant aquatic plant in Florida, hydrilla covered approximately 95,000 ac. (38,500 ha) in 1994. In 1994–1995, Florida spent about $14.5 million, not including loss of income from curtailed recreational activities, on controlling hydrilla. From 1980 to 2005, Florida spent $174 million. Millions are spent each year on herbicides and harvesters just trying to control the plants. Management. Hydrilla has been successfully eradicated from several sites in California and Washington. Because hydrilla grows new plants from pieces, physical means of control such as harvesting or chopping only serve to spread the infestation. Small populations can be harvested if all parts are removed from the water. Sites should be closely monitored for regrowth. Mechanical harvesting of large areas can cost $1,200 or more per ac. ($2,950 per ha) and is usually prohibitive because as many as six harvests a year are required due to the plant’s rapid growth. Mechanical harvesting is used to open boat lanes in waterways that are totally infested. In regulated areas such as reservoirs, water drawdown may be somewhat effective in reducing stem densities, but it will not kill the plants because of regrowth from tubers. Covering bottom sediment with opaque fabric that totally blocks light will suppress growth around boat docks or swimming areas. Chemical control is possible with herbicides approved for water use. Fluridone, slow to take effect, will reduce infestations but will not eliminate hydrilla. Endothall is used when results are desired more quickly. The most effective biological control is grass carp (see Volume 1, Vertebrates, Fish, Grass Carp) (Ctenopharyngodon idella), also called white amur, a nonnative invasive fish that consumes hydrilla. Care must be taken that no fish escape the target water body, because they will eat all aquatic plants, including natives. Grass carp are prohibited in most states unless the fish are sterile. Since 1981, over 40 insects that feed on hydrilla have been identified in various parts of the world. Possibilities include a beetle (Bagous affinis) from India and Pakistan, whose larvae eat hydrilla tubers. The beetle requires alternating wet and dry periods that may be simulated by artificial drawdowns. No established populations of the beetle exist in the United States. Of two leaf-mining flies (Hydrellia pakistanae and H. bulciunasi) released in Florida, one had no impact, and the other had limited success. An aquatic moth (Parapoynx diminutalis), accidentally released, defoliates plants, but stems remain viable. Tropical insects may not do well in northern climates.

Selected References Evans, Chris, and Joseph LaForest. “Hydrilla verticillata.” Center for Invasive Species and Ecosystem Health, University of Georgia, 2008. http://wiki.bugwood.org/Hydrilla_verticillata. “Hydrilla (Hydrilla verticillata).” Non-native Invasive Freshwater Plants, Department of Ecology, State of Washington, n.d. http://www.ecy.wa.gov/programs/wq/plants/weeds/aqua001.html. Masterson, J. “Hydrilla verticillata.” Smithsonian Marine Station at Fort Pierce, 2007. http://www.sms .si.edu/irlSpec/Hydrilla_verticillata.htm. Ramey, Victor. “Hydrilla verticillata.” Center for Aquatic and Invasive Plants, University of Florida, 2001. http://plants.ifas.ufl.edu/node/183.

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Successful Hydrilla Eradication in Washington State

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robably introduced with nonnative water lilies, hydrilla was discovered on June 1, 1995, in two interconnected lakes, Pipe Lake and Lucerne Lake, in Washington. These two lakes north of Seattle comprise 73 ac (30 ha). From 1995 through 2000, the entire lake system was treated yearly with an aquatic herbicide. Although the population of hydrilla thinned, new tubers germinated. No sprouts developed, however, from seeds or turions. In 2001 and 2002, selectively treating sections of the lake where hydrilla still existed was not effective. In 2003, herbicide applications combined with divers and snorkelers hand-pulling plants succeeded in ridding the lakes of hydrilla. Since 2004, no plants were reported in Lucerne Lake, and as of 2007, none were found in either lake. Monitoring continues. Source: Department of Ecology, State of Washington, n.d.

n Water Chestnut Also known as: Ball nut, European water chestnut, water caltrop, horned water chestnut, water-chestnut Scientific name: Trapa natans Synonyms: Trapa bispinosa, T. natans var. bispinosa, T. natans var. natans Family: Water Caltrop (Trapaceae) Native Range. Western Europe, northern Africa, and Asia, including the Indus River basin, southeastern China, and Vietnam. Possibly southern Africa. Distribution in the United States. From the northeastern states west to Wisconsin and south to Virginia. The worst infestations are in Chesapeake Bay and the Potomac River and in the Connecticut River Valley, Hudson River, and Lake Champlain region. It has the potential to spread to warm temperate and subtropical regions. Description. Water chestnut is an aquatic annual with stems that anchor in the muddy substrate. A system of long, fine roots holds the long stems in the mud. Feathery leaves grow in whorls around the submerged stems, which can grow 13–16.5 ft. (4–5 m) tall, depending on water depth. These sessile stem leaves are similar to adventitious root hairs. At the surface, the stem terminates in a rosette of floating leaves. The glossy rosette leaves, 0.75–1.5 in. (2–4 cm) long, are triangular and saw-toothed. An inflated spongy petiole, 6 in. (15 cm) long, gives the rosette buoyancy. In late June to mid-July, inconspicuous white flowers develop in the center of the leafy rosettes. Flowers, which have four 0.3 in. (8 mm) long petals, are insect pollinated. Each flower produces one black fruit that contains one seed. Also called a nut, the fruit is a woody ball, about 1 in. (2.5 cm) wide and weighing 0.2 oz. (6 g). The four triangular sepals

The Water Chestnut

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he water chestnut used in Chinese cooking is Eleocharis dulcis, in the sedge family (Cyperaceae). The corms are the edible part.

336 n AQUATIC PLANTS become hard horn-like prongs on the fruit. The prongs or horns, as long as 0.5 in. (1.25 cm), are covered with backward pointing barbs. Fruit develops in the water, just below the surface leaf rosette. As annuals, plants die in the fall and do not overwinter in the water. Regrowth is from the nuts. Related or Similar Species. No related species of Trapa, or any other genus of the eastern hemisphere family Trapaceae, occur naturally in the United States. Native to China, Trapa bicornis, called devil pod, bat nut, or horn nut, is used for food in Asia. The glossy black nut, 2.5–3 in (6.3–7.6 cm) has two distinct horns and resembles the profile of a bat in flight. Although not commonly known and not found in natural settings in the United States, Trapa bicornis is a noxious weed in the state of Washington. It is a problem in the Caspian Sea and in irrigation systems in India. Other water plants have Although present in the United States since the mid-1800s, water some of the same characterischestnut remains localized in the northeastern states. (Native range tics. The introduced waterhyaadapted from USDA GRIN and selected references. Introduced range cinth, also popular in the adapted from USGS Nonindigenous Aquatic Species Database and aquarium and water garden selected references.) trade, can be distinguished by its tall spike of showy lavender flowers. Neither Eurasian watermilfoil (see Aquatic Plants, Eurasian Watermilfoil) nor hydrilla (see Aquatic Plants, Hydrilla) have a floating rosette of leaves. Introduction History. The specific origin of the genotype in the United States, first seen in 1859 in Massachusetts, is unknown. In 1877, the well-known botanist Asa Gray cultivated it in his botanical garden in Cambridge, Massachusetts, and by 1879, it had escaped to local waterways. By 1884, a population was noticed near Scotia, New York, followed by populations in Vermont and Massachusetts. By 1923, plants were growing in Maryland, and the species had spread 40 mi. (65 km) up the Potomac River outside Washington, D.C., covering about 10,000 ac. (4,000 ha). Although the Army Corps of Engineers attempted to remove the infestation, water chestnut had migrated to the Bird River in Baltimore County by 1955, and to the Sassafras River, a tributary to Chesapeake Bay, by 1964. Sometime before the late 1950s, water

WATER CHESTNUT n 337

A. Populations can rapidly increase to completely cover water bodies. B. Small white flowers have four petals and four sepals. C. Woody fruit have four distinctive “horns.” D. Glossy triangular leaves float in rosettes on the water surface. (Leslie J. Mehrhoff, Ecology and Evolutionary Biology University of Connecticut, Bugwood.org.)

chestnut was introduced into one of the New York Finger Lakes, part of the larger Great Lakes Basin, possibly as a result of the connection with the Mohawk River via the Erie Canal. The plant is now established in parts of Lake Ontario. In 1998, it was found in the South River in Quebec, which has connections with Lake Champlain. Introductions may have been intentional, as food for waterfowl, or accidental, from water gardens. Habitat. Water chestnut is found in shallow, nutrient-rich, fresh-water lakes and rivers, generally with a pH of 6.7–8.2. Water is usually stagnant or slow moving. Plants can grow in water as deep as 16.5 ft (5 m), but are usually found where depth is 1–6.6 ft (0.3–2 m). Reproduction and Dispersal. Water chestnut reproduces both by seed and asexually. Flowers develop from the center of the rosette on the water surface, but as new leaves are produced on the meristem, the older leaves and developing fruit sink below the surface. Fruit ripens in about one month, and the mature fruit falls to the bottom of the water body where it remains during winter. The prongs or horns on the fruit may serve to help anchor the seed. Seeds need a dormancy period of about four months and germinate in late spring on bottom sediments. Although most seeds germinate in the first two years, they are viable for as long as 12 years. Leaves, which enable the plant to photosynthesize, develop on the stem while it is growing toward the surface. The stem and leaves reach the surface by midMay. After the rosette develops at the surface, the stem branches, growing secondary stems which also produce rosettes. One rooted stem can create 15–20 rosettes, and each rosette can produce as many as 20 flowers and 20 seeds. One acre (0.4 ha) of water chestnut can produce enough seeds to cover 100 ac. (40 ha) the following year. Asexual dispersal occurs when plants are uprooted or rosettes break free to float with currents and waves. Nuts are also dispersed by water and may become trapped in feathers of waterfowl. Human activity is a major means of dispersal of water chestnut. It is an ornamental in aquariums and water gardens in the United States and may be improperly disposed of into natural water bodies. Impacts. Infestations of water chestnut have both ecological and economic impacts. Plants grow rapidly, and infestations can increase dramatically. A population of 50 plants in 1997 on the Bird River in Maryland increased to cover more than three ac. (1.2 ha) in 1998. By 1999, it covered 20 ac. (8 ha). Floating rosettes of water chestnut can create mats that completely cover the water surface, blocking light to the water below. Density of rosettes on the water surface can be as many as 5 per sq. ft. (50 per m2), which can cover the surface with leaves three layers deep.

338 n AQUATIC PLANTS The shade suppresses the growth of other submersed or floating water plants. Because plants are annuals, much dead material is discarded each year, which changes the water quality. Reduction of oxygen levels kills fish. Mats of vegetation interfere with navigation and recreational activities, such as boating, fishing, and swimming, particularly along shorelines. Bays of southern Lake Champlain, which were previously used for fishing, are now inaccessible. The spiky seeds are hard enough to puncture shoe leather and can severely damage bare skin. Removal is expensive and labor intensive. In 2002, Vermont allotted $500,000 to harvest and remove water chestnut. Management. Although control and eradication are difficult, efforts in the 1950s and 1960s by the Army Corps of Engineers succeeded in controlling water chestnut in the United States. When the program was suspended, however, due to its success and budget problems, populations rebounded. By 1994, water chestnut infested more territory than it had before control efforts were begun. Physical control includes hand removal, pulling and raking plants from boats. Plants are easily pulled out of the mud, allowing small populations to be removed. Because seeds are viable for several years, however, eradication is not ensured. Large populations, thick mats that cover miles of river, require both mechanical harvesting and herbicides. Mechanical removal and harvesting by volunteers removed approximately 400,000 lb. (181,500 kg) of water chestnut from the Bird River and Sassafras River in Maryland in 1999. Machinery, however, cannot operate in the shallow water occupied by much of the water chestnut. Chemical applications of 2,4-D are somewhat helpful, and the herbicide seems to have no adverse effect on wildlife. The search for natural enemies of water chestnut that could be used for biological control has been conducted in Western Europe and northeastern Asia, where the extremes of the temperate zone climates are similar to those of regions infested in the United States. A leaf beetle (Galerucella bimanica), which is widespread in northeastern Asia, can cause complete defoliation of whole populations. Different stages in its life cycle eat different parts of the leaves, leaving only a vein skeleton behind. However, the beetle also attacks many other plants and is a pest of cultivated water chestnut in Asia. A related species, Galerucella nymphaeae, which is most common in Europe, does less damage but also feeds on water lilies. Two weevils, Nanophyte japonica from central Japan and China and an unidentified Nanophyte species from China and Russia, eat leaves. Although both appear to feed only on Trapa species, neither produces much damage. Biological agents from India cannot survive the cooler climate in the northeastern United States, but searches can be conducted in tropical and subtropical areas of its native range if water chestnut expands its distribution to the southern United States.

Not Invasive Everywhere

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opulations of water chestnut are dwindling so much in Europe that it has become rare. The Council of Europe declared it a protected species. In Asia, it has both nutritional and medicinal value. The nutlike fruit is cultivated and used as food for both humans and livestock. Parts of the plant are also used to treat elephantiasis, fevers, rheumatism, and skin disorders.

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Selected References Cao, Ling. “Trapa natans.” USGS Nonindigenous Aquatic Species Database, Gainesville, Florida, 2010. http://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=263. Pemberton, R. W. “Water Chestnut.” In Biological Control of Invasive Plants in the Eastern United States, by R. Van Driesche et al. USDA Forest Service Publication FHTET-2002-04, Morgantown, WV, 2002. http://wiki.bugwood.org/Archive:BCIPEUS/Water_Chestnut “Water Chestnut, Trapa natans.” Invasive Species in the Chesapeake Bay Watershed Workshop, Sea Grant, MD, 2007. http://www.mdsg.umd.edu/issues/restoration/non-natives/workshop/water _chestnut.html.

n Waterhyacinth Also known as: Water-hyacinth, floating water hyacinth Scientific name: Eichhornia crassipes Synonyms: Eichhornia speciosa, Piaropus crassipes, P. Mesomelas, Pontederia crassipes, Heteranthera formosa Family: Pickerelweed family (Pontederiaceae) Native Range. Amazon Basin of northern South America, from Venezuela to Brazil. Distribution in the United States. Widespread from New York state west to Wisconsin, Texas, and Colorado, and in the Pacific Coast states. A problem primarily in the southeastern states and in California, Hawai’i, Puerto Rico, and the Virgin Islands. Description. Waterhyacinth is a floating perennial plant that forms a rosette of leaves above the surface of the water. While the rosette of leaves extends from a few inches to over 3 ft. (1 m) above the water surface, 16 in. (40 cm) is most common. Leaves, borne upright on stalks, occur in whorls of 6–10. The round or oval leaves, up to 10 in. (25 cm) wide, but more likely 6 in. (15 cm) or less, are thick and leathery, waxy or glossy. They are slightly curved inward toward the stem and sometimes have wavy edges. The stems, which are actually leaf petioles, are spongy air-filled tissue, bulbous and inflated, which enables the plant to float. Petioles, usually up to 12 in. (30 cm) long, are short in uncrowded conditions, but elongate where plants become crowded. Each plant sends out floating stolons in all directions. The combination of many plants and associated intertwined stolons forms dense, impenetrable mats that can be 6.5 ft. (2 m) thick. Approximately 50 percent of the plant biomass is fibrous roots, extending deep into the water. Many fine lateral roots give the roots a distinctly feathery appearance. Showy flowers, usually 8–15 on each inflorescence, grow in clusters at the top of a 12–19.5 in. (30–50 cm) stalk which extends above the leaves. The six-petaled flowers, 1.5–2.8 in. (4–7 cm) in diameter, are lavender, purplish blue, or pinkish, with bright yellow centers. Thin, delicate petals are oval or oblong. The flowers have 6 stamens and 3 stigmas. The fruit is a thin-walled capsule with three cells. Each capsule usually contains about 50 seeds, but can have as many as 450. Seeds are small, 0.2 by 0.04 in. (5 by 1 mm), with longitudinal ridges. As the fruit matures, the flower stalk bends to release the seeds under water. Related or Similar Species. Other Eichhornia species from South or Central America are less invasive. Anchored waterhyacinth is listed as a Federal Noxious Weed. Because it must be rooted, it occurs only in shallow ponds or along the shorelines of lakes and rivers. Variable leaf waterhyacinth, native to Puerto Rico, is considered difficult to maintain in an aquarium and is unlikely to be found naturalized. Leaves beneath the water surface are

340 n AQUATIC PLANTS linear, while those floating on the surface are round. Brazilian waterhyacinth, native to Brazil, is found only locally in Florida. Introduction History. Waterhyacinth was introduced as an ornamental at the Cotton States Exposition in New Orleans in 1884. Within 70 years, these fast-growing plants covered 126,000 ac. (5,100 ha) in Florida. Plants are widely available in nurseries for fish ponds and aquariums. Habitat. Although most often found floating in water, waterhyacinth plants can survive for months on moist sediment. They have a wide tolerance to environmental conditions, including nutrient levels, temperature, and toxic substances. Optimum water temperatures are 77–86°F (25–30°C). Temperatures below 54°F (12°C) and above 92°F (33°C) inhibit growth. Although its range is limited by cold, it is able to grow new leaves after mild freezes. In northern states, plants will grow only during the summer and After introduction to New Orleans as an ornamental plant, waterhyacinth cannot survive cold winters. A spread throughout most of the warmer states, primarily due to the water hard frost will kill the plant, garden industry. (Native range adapted from USDA GRIN and selected but reinfestation may occur references. Introduced range adapted from USGS Nonindigenous from seeds. Waterhyacinth will Aquatic Species Database and selected references.) grow in water with a pH of 4–10, but it prefers neutral, nutrient-rich water. It can also survive in water with salinity as high as 0.24 percent, and is tolerant of water level changes and variations in water flow. Plants need high light levels to thrive. Reproduction and Dispersal. Waterhyacinth plants produce seeds, but reproduction and spread is primarily vegetative. New plants form at nodes along the floating stolons that radiate from the parent plant. Plants grow very fast, and populations can double in six days. Results of one study showed that only two plants produced 1,200 daughter plants in only four months. When they break free, these new plants are spread by water currents or pushed by the wind and redistributed to form new colonies. Plant pieces are frequently carried to new locations on boats and trailers. Improper disposal of excess or unwanted plants, such as dumping into a canal or lake, can create additional invasive populations.

WATERHYACINTH n 341

A. Rapidly growing plants can quickly cover acres or entire lakes. (Graves Lovell, Alabama Department of Conservation and Natural Resources, Bugwood.org.) B. Spongy, inflated petioles enable plants to float. (Richard Old, XID Services, Inc., Bugwood.org.) C. Glossy leaves encircle a showy inflorescence. (Wilfredo Robles, Mississippi State University, Bugwood.org.) D. Roots are thick and feathery. (Rebekah D. Wallace, Bugwood.org.)

Although plants can flower several times a year, and one plant can produce over 3,000 seeds, expansion by sexual reproduction is limited. Fruit and seeds are rare except in warmer climates, and few seedlings are seen in the field. Plants are self-fertile but are also pollinated by bees. The number of fruit produced per plant is highly variable, and under high temperatures and low relative humidity, few fruit develop. Seeds remain viable in mud for 15–20 years and are able to survive on both muddy banks and on waterhyacinth mats. Germination requirements are not clearly determined, but high light intensities and alternating temperatures favor the process. Buried seeds fail to germinate. Birds may also transport seeds to new areas, and seeds may also be carried on boats and trailers. Impacts. Waterhyacinth infestations alter hydrologic systems, impede water traffic, degrade recreational sites, change water chemistry and quality, decrease biological diversity, damage wildlife habitat, and increase habitat for undesirable species. Because of rapid growth, infestations can quickly cover many acres. Mats of waterhyacinth can completely cover lakes, rivers, canals, and ditches and can be dense enough for a person to walk on. One acre of healthy plants can weigh 200 or more tons. Plants can block drainage and cause flooding, impede water flow for irrigation, and clog pumps for hydroelectric power. Mats may also increase the sediment load by interfering with drainage. Floating mats can envelop water ways, making them impenetrable by watercraft, both commercial and recreational. Swimming sites are overrun with plants, and waterfront properties have suffered a decrease in value because of waterhyacinth. Mats restrict fishing access, and equipment can become entangled and lost in the root systems. Alterations in the water environment, such as warmer water temperatures beneath dense mats, change the species composition and reduce the number of sport fish. The mats reduce oxygen supply in the water by covering the surface and preventing gas exchange with the atmosphere. Waterhyacinth reduces biological diversity because it shades out native water plants, crushes them with the weight of the mat, or literally pushes them away. With no light, phytoplankton cannot survive, which alters the invertebrate composition and also the fish diversity. When native aquatic plants die, they further deplete oxygen supplies as they decay and add organic matter to the water. As a result, fish and other water

342 n AQUATIC PLANTS fauna suffocate. As well as blocking access to water for land animals, dense mats also eliminate native plants those animals depend on for food, nesting, or shelter. In the Florida Everglades, for example, the snail kite, a raptor that feeds on apple snails, is negatively impacted because waterhyacinth has smothered the aquatic food plants for the snails. Fish-spawning areas and waterfowl habitat are diminished. The moist mats increase habitat for undesirable mosquitoes and parasitic flatworms and can provide microhabitat for insects that spread diseases such as schistosomiasis and malaria in favorable climates. Because evapotranspiration from plants can be 1.8 times that of an open water surface, the growth of the plants can substantially decrease the water supply. Control of waterhyacinth, often merely to a maintenance level, costs several millions of dollars each year. Management. Preventing the spread of waterhyacinth is a key to its control, because even one plant can quickly produce hundreds. Garden pond plants must not be disposed of in native waterways. Boats and equipment used in water must be thoroughly cleaned of all plant debris before being transferred to other water bodies. Because of the vast scale of infestation once plants become established, physical methods of eradication, such as dumping plants onshore to die or chopping them to small bits, are expensive and have limited effectiveness. Not only is removal a short-term solution, but the requirements for transportation of plants, both on the water and on land, is enormous because of the weight of the plants, which are 95 percent water. Chemical control is also limited, not only because of expense but because some herbicides cannot be used around water because of detrimental effects on water ecosystems. Some formulations of glyphosate can kill waterhyacinth in eight weeks. Although it is nontoxic to fish, glyphosate is slightly toxic to aquatic invertebrates. Applications of 2,4-D are most effective, especially in hot weather. It is selective to broadleaf plants and some monocots, including waterhyacinth, but is somewhat toxic to birds, fish, and aquatic invertebrates. Copper sulfate or copper chelate inhibit growth but are toxic to fish, especially trout, and to some mammals, aquatic invertebrates, and soil organisms. Biological control may be somewhat accomplished with plant-eating fish or insects. Although fish eat the roots and do not destroy plants, they may be used to reduce densities in sport-fishing areas. Possible species include Chinese grass carp (see Volume 1, Vertebrates, Fish, Grass Carp) (Ctenopharyngodon idella) and two tilapia species (Tilapia melanopleura, T. mossambica). Chinese grass carp prefers other foods but will feed on waterhyacinth where it is dense or where little else is available. Because of their diet preferences, they can also reduce the abundance of native plants. Several states require that any individuals imported be sterile so they do not outcompete stocked fish or damage native aquatic vegetation. Other biological control, however, is promising, and over 100 species of insects have been considered. Two weevils (Neochetina bruchi and N. eichhorniae), native to Argentina, control the plant in some locales, but success has been inconsistent. The weevils place eggs inside plant tissue, where larvae then feed and weaken the plant. Because they also feed on native pickerelweed, however, they are not suitable for use in the United States. Similarly, the waterhyacinth moth (Sameodes = Niphograpta albiguttalis) and a mite (Orthogalumna terebrantis) may also damage native plants. Biological control is slow relative to the rapid growth and spread of the plants. New research involves species of Thrypticus flies and plant-hopper species of Taosa and Megamelus, all native to the source regions of waterhyacinth. The fly larvae feed on leaf stalk tissue, while the plant-hoppers are sap-sucking insects that insert pathogens into the plants, weakening them. Two possible fungus species, Acremonium

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Is Waterhyacinth Good for Anything?

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everal projects involving practical uses of waterhyacinth, some which are more applicable to developing countries, are being conducted in various parts of the world. The fibrous tissue, when blended with other materials, makes a suitable paper or fiber board. Dried plants are woven into baskets and matting, and rope made from the fibers is used to wrap around canes to make a type of durable rattan furniture. Because the roots harbor aerobic bacteria that feed on waste, plants may be used to filter sewage. Plants or their roots provide nutritious food for pigs, ducks, and pond fish such as carp, tilapia, or catfish. Other ideas include molding charcoal briquettes from burned remains, development of biogas, or use as fertilizers, mulch, or compost.

zonatum, associated with the waterhyacinth mite, and Cercospora rodmanii, native to the southeastern United States, currently provide low levels of control.

Selected References Batcher, Michael S. “Element Stewardship Abstract, Eichhornia crassipes.” Global Invasive Species Team. The Nature Conservancy, 2000; updated 2009. http://wiki.bugwood.org/Eichhornia _crassipes. Center, T. D., H. Cordo, M. P. Hill, and M. H. Julien. “Waterhyacinth.” In Biological Control of Invasive Plants in the Eastern United States, by R. Van Driesche et al. USDA Forest Service Publication FHTET-2002-04, Morgantown, WV, 2002. http://www.invasive.org/eastern/biocontrol/4 WaterHyacinth.html. “Water Hyacinth.” Practical Answers, Technical Information Online, n.d. http://practicalaction.org/ practicalanswers/product_info.php?products_id=189. “Water Hyacinth, Eichhornia crassipes.” Center for Aquatic and Invasive Plants. University of Florida, IFAS, n.d. http://plants.ifas.ufl.edu/node/141.

n Forbs n Canada Thistle Also known as: Californian thistle, creeping thistle, field thistle, corn thistle Scientific name: Cirsium arvense Synonyms: Cirsium setosum, Breea arvensis, B. incana, Carduus arvensis, and others. Family: Sunflower (Asteraceae) Native Range. Southwestern Asia, including Afghanistan, Iran, Turkey, and the Caucasus region. Widespread, and possibly native to Europe and more extensive areas in Asia. Distribution in the United States. Most of the country except the southern states and Hawai’i. Especially invasive in the northern states, from northern California east to Maine and south to Virginia. The southern limit may be influenced by high summer temperatures and shorter summer days. Description. Canada thistle is an herbaceous perennial with erect stems growing 1.5–4 ft. (0.5–1.2 m) tall, branching toward the top. It has four interfertile varieties, the most common being Cirsium arvense var. horridum and numerous genotypes, which account for its variable appearance. New shoots and seedlings initially form a rosette, although it may be poorly developed with few leaves. Mature plants may have several slender stems arising from the root system. Stem leaves are sessile and alternate. All leaves are oblong to lanceshaped, 2–8 in. (5–20 cm) long, with either entire or shallowly lobed and toothed, spiny margins. The undersides of leaves are often covered with soft, wooly hairs, but the upper surface is green and glabrous. Unlike many other thistles, leaf bases do not extend down the stem to form wings, and the stem is almost glabrous. The plant has a deep, extensive network of both horizontal and vertical roots. Seedlings first grow a fibrous taproot that serves as a storage organ, before developing creeping roots in 2–4 months. Although primarily in the top 18–24 in. (45–60 cm) of soil, the vertical roots may extend down 6.5–10 ft. (2-3 m), and sometimes as deep as 23 ft. (7 m). The horizontal roots can spread outward several feet, and although brittle and easily fragmented, can survive in frozen soil. Canada thistle is dioecious, meaning that male and female flowers are on different plants. Although a patch may be all one sex, both male and female plants can develop from the same clone. The flowers, which bloom from June to October, are rose-purple, lavender, or sometimes white. Cylindrical, oval, or bell-shaped flower heads grow in umbrella-shaped clusters. Female flowers may have a distinct vanilla-like smell. Flower heads are 0.4–0.75 in. (1–2 cm) in diameter, and the spines are short and slender. The involucre, or whorl of bracts beneath the flower head, is purplish and either glabrous or with white wooly hairs. Old, dry flower stems remain standing erect. Fruits are small and dry brownish or tan achenes, with a tan, feathery appendage called a pappus. The pappus in Cirsium species has branched hairs, giving the genus the general name of “plumed thistles.” Male flowers have a slightly shorter pappus without a seed, 0.4–0.6 in. (1–1.4 cm), compared with the pappus on female flowers, 0.6–0.8 in. (1.5–2 cm). The pappus on both types of flowers is deciduous, leaving most seeds in the flower head.

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Related or Similar Species. Several Cirsium species are native to the United States. Yellowspine thistle, native to the southwestern United States is a clump-forming perennial similar in size to Canada thistle but with narrower lanceshaped leaves, 4–10 in. (10– 25 cm) long and less than 1.2 in. (3 cm) wide. Its stems are not winged and are densely wooly. Leaf margins are deeply and coarsely lobed and toothed. Lower leaf surfaces are densely wooly, while the upper surfaces are grayish and only lightly covered with white wooly hairs. White, pink, or pale purple flower heads, 0.8–1.6 in. (2–4 cm) long, have a sparse cover of white wooly hairs. The stout, yellow spines, 0.1–0.5 in. (5–12 mm) long, are spreading or curved slightly downward. Seeds are pale orangish brown with tan pappus bristles, 1–1.2 in. (2.5–3 cm) long. Wavyleaf thistle, native to the western third of the United States and spotty in eastern states, is also known as gray Canada thistle grows best in northern climates with long summer days. thistle and hybridizes with yel- (Native range approximated from USDA GRIN and selected references. lowspine thistle. Although it Introduced range adapted from USDA PLANTS Database, Invasive Plant grows in compact clumps, it is Atlas of the United States, and selected references.) not a widely spreading species because its lateral roots are short and only weakly creeping. The shallow and coarsely lobed leaves resemble those of yellowspine thistle, but rosette leaves are longer, 6–12 in. (15– 30 cm), and more than 1.2 in. (3 cm) wide. Stems are densely wooly and not winged. Upper leaf surfaces are lightly wooly. Flower heads resemble those of yellowspine thistle, but have short, slender spines. Its seeds are tan. Several thistles native to Europe and North Africa are pests that resemble Canada thistle. The pappus of Carduus species is not branched or feathery. The taxonomy of musk thistle is not clear (see Forbs, Musk Thistle). It may be several species or several subspecies. This biennial species is common in southern California, the Midwest, and Appalachia. Bull thistle is a biennial found throughout the United States, growing best in heavy, fertile soils. Reaching 6.5 ft. (2 m) tall, it has foliage with stiff hairs and prickly, winged stems caused by the leaf bases extending down the stem. Stems and undersides of leaves are

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A. Stems may branch near the top. (Steve Dewey, Utah State University, Bugwood.org.) B. Lobed and toothed rosette leaves have spiny margins. (Ohio State Weed Lab Archive, The Ohio State University, Bugwood.org.) C. Flowers are usually purple or lavender, and white flowers (right) are rare. (Steve Dewey, Utah State University, Bugwood.org.) D. The involucre is the whorl of bracts beneath the flowerhead. (Chris Evans, River to River CWMA, Bugwood.org.) E. Seeds of the female flower heads have a long pappus. (Richard Old, XID Services, Bugwood.org.)

covered with a network of white hairs that resemble cobwebs. The upper leaf surface is bumpy and covered with long, stiff hairs. Bull thistle has a thick, fleshy taproot, sometimes branched, extending 28 in. (70 cm) deep. Common in coastal California, Italian thistle is rare elsewhere in the United States. It is a summer annual with seeds that generally germinate the following spring. Milk thistle is a pest in the dry coastal regions of California. As a winter annual, it germinates in late summer or fall, producing flowers and seeds the following spring or summer. Introduction History. Canada thistle was inadvertently brought to the United States in the early 1600s. It was declared a noxious weed in Vermont by 1795 and in an additional 43 states by 1954. Habitat. Canada thistle commonly invades disturbed sites, even the modest soil erosion caused by gopher mounds, and is rare in healthy pastures. It is common on altered sites, such as road and railway right-of-ways, pastures, agricultural fields, and abandoned fields. It is frequently found in moist upland environments, such as prairies and grasslands in the Midwest and Great Plains, and in riparian habitats in the Intermountain West. In the eastern states, it grows in drier habitats, such as sand dunes and sandy fields. Because plants do not tolerate shade, Canada thistle grows only in non-forested sites. It grows in a variety of soil textures, including clay, loam, silt, gravel, and chalk, but prefers deep, well-drained mesic soils and will not tolerate waterlogged soils. The plant can also tolerate 2 percent salt. Reproduction and Dispersal. Canada thistle reproduces both sexually and vegetatively. Because it is a long-day plant, meaning that at least 14 hours of daylight are required for flowering, plants have more flowers and a longer bloom period at higher latitudes. In order to produce seed, female plants and male plants must be within 0.25 mi. (0.4 km) of each other. Some predominantly male plants, however, are self-fertile, with both male and female flowers. Seed develops 8–10 days after insect pollination. One plant may produce 5,000 seeds each year, and a dense thicket covering 10 sq. ft. (1 m2) can produce over 70,000 seeds.

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Although the bristly plumed seeds may be wind-dispersed more than 0.6 mi. (1 km), the pappus breaks off easily, and most seeds fall near the parent plant. Seeds may also be dispersed by water, in animal droppings, by birds and small mammals, and by human activity, such as on vehicles and equipment or as a contaminant in packing material, soil, crop seed, or hay. Most seeds germinate within one year, but unless deeply buried, some remain viable in the soil for 20 or more years. Germination is best in the top 0.4 in. (1 cm) of soil, at 68–86ºF (20– 30ºC) with abundant moisture, bright light, and little competition. Canada thistle does not easily establish from seed where soil is undisturbed, and seeds have low viability after passing through a digestive tract. Germination and rosette growth take place in mid to late spring, and seedlings rapidly develop a root system. Roots may initially grow 0.4 in. (1 cm) per day, and the plant grows a vertical root 5 ft. (1.5 m) deep in the first year. Plants flower the following summer. Most germinating seeds become female plants. Local expansion is by roots and shoots. Canada thistle forms clumps or patches because of its creeping root system. Although most horizontal roots grow 3.3–6.6 ft. (1–2 m) a year, they can grow as much as 19.5 ft. (6 m) in one season, radiating away from the parent plant. The shoots develop in winter and emerge in spring, from as much as 3 ft. (1 m) beneath the surface. Wherever a vertical shoot grows, approximately every 2–3 ft. (0.6–0.9 m), another horizontal root and a vertical root develop in the same location. Because sprouts develop quickly as the horizontal root grows, the lateral roots do not extend very far beyond the perimeter of the thicket. Although growth and density of shoots varies with environmental conditions, 3.3 ft. (1 m) of horizontal root may have 8–24 buds. Root buds, however, are not necessary. New shoots may sprout from root fragments less than 1 in. (2.5 cm) long and create a clone 9 ft. (2.8 m) in diameter in one year. Most roots live only two years, but the plants grow new sections every year. Stem pieces also grow new plants. Whether from seed or from roots or stems, plants grow quickly after a rosette stage lasting 2–4 weeks. When plants bolt, the flowering stems may grow 1.2 in. (3 cm) per day, and flower after 10 weeks. Because root buds produce new shoots all summer, a stand may be in several stages of growth. Impacts. Because of its creeping root system, Canada thistle readily establishes and crowds out native plant species. Clones can reach 115 ft. (35 m) in diameter. It changes the structure of the community, displaces native species, and reduces plant and animal diversity. Plants can produce as many as 29 flowering shoots in 10 sq. ft. (1 m2), shading out other plants and directly competing for water and soil nutrients. Canada thistle may also have alleleopathic qualities. Insect pollinators may prefer Canada thistle flowers, to the detriment of native plant species. Although plants may accumulate nitrates that are toxic to animals, the substance causes few problems because the plants are not grazed by livestock. Spiny leaves scratch or puncture livestock hides, resulting in infections. Canada thistle costs tens of millions of dollars in crop loss annually, and millions for control. Shoot densities of fewer than 2 per 10 sq. ft. (1 m2) may cause a 15 percent loss in forage. A density of 20 shoots per 10 sq. ft. (1 m2) can cause a yield loss of 35–50 percent in crops, such as barley, winter wheat, or alfalfa. It is a host for the bean aphid and bean stalk borer, which affect corn and tomatoes, and is a host for the sod-web worm, which also affects corn crops. Density of standing stalks and litter can increase both fire frequency and intensity. Management. Eradication is difficult once Canada thistle is established, and plants should be removed when first spotted. A combination of methods is most effective. Different ecotypes, however, respond differently to management methods, and results are highly variable. Regardless of the method used, priority should be given to killing the entire

348 n FORBS clone, including the root system and any root pieces. Although spread by seed is relatively rare, an additional goal should also be decreased seed production and destruction of the seed bank. The best control is to prevent infestation by maintaining good pastures, but treated areas may be re-infested from areas not cared for, such as roadsides. Removal of Canada thistle by physical means is difficult. Occasional cultivation or mowing are poor practices because they stimulate growth of horizontal roots, and cultivation breaks roots, which sprout new plants from pieces. Repeated cultivation or mowing, however, especially when done in early spring before much growth has taken place, can deplete root reserves. Cultivating 3–4 in. (7.5–10 cm) deep every 20 days can eliminate up to 90 percent of plants. Mowing every 7–21 days for four years may eliminate the plant. Cultivation and mowing, however, are not appropriate in natural areas. Prescribed burns done during the dormant season may stimulate native species to grow, which both decreases the amount of bare soil and shades out Canada thistle. Fire during the growing season, however, damages native plants. Grazing is ineffective because livestock do not eat Canada thistle and avoid areas where it grows, giving it a competitive advantage. Because Canada thistle is not competitive in shade, planting crops such as alfalfa may prohibit its early establishment. Chemical applications are most successful when physical means are used to stress the plant early in the season. They may not be appropriate, however, for natural areas where herbicides can also kill native plants, alter succession, and open the site for more invasion. Depending on the site and growth stage of Canada thistle, herbicide possibilities include glyphosate, clopyralid, and chlorsulfuron. Picloram, dicamba, metsulfuron, and 2,4-D are not recommended, either because they are ineffective or are too damaging to native species. Different clones have varying tolerances to herbicides, and Canada thistle’s deep root system makes plants resistant. Applications are most successful on young plants or plants weakened by mowing or tilling and should be done before flowering to prevent seed production. Care should be taken to treat all areas because plants do not always remain connected as roots die or are severed. Chemical applications are most effective when combined with physical or biological controls, such as the European seed weevil. Biological control is not promising. Canada thistle is a major crop pest in its native European range where no major enemies keep it under control. Potential insects must be host-specific to avoid adverse impacts on native Cirsium species or crop plants, such as safflower and globe artichoke, which are closely related to Canada thistle. Most insects weaken and kill individual plants, but do not offer widespread eradication, and no one agent is totally effective. Larvae of the native painted butterfly (Vanessa cardui) defoliate local areas, but their populations vary yearly with migrations. This butterfly occurs primarily in the southern states and also affects other Cirsium species. Several insects have been introduced, either accidentally or intentionally, and may be established in different parts of the country. An Asian beetle (Altica carduorum), released in 1966, eats leaves during summer, defoliating and weakening plants but failing to kill them. Stressed plants, however, produce fewer shoots and seeds. This beetle has not become established due to predation. The Canada thistle stem weevil (Ceuthorhynchus litura), intentionally released in 1971–1985, eats stems, but plants recover with new shoots. Although it does not attack crops, it feeds on all Cirsium species, including natives. A bud weevil (Larinus planus) eats seed heads but has little effect and also attacks native thistle species. A thistle stem gall fly (Erophora cardui), released 1981–1985, feeds primarily on Canada thistle shoots, and a seed-head fly (Terellia ruficauda) destroys seeds. Larvae of a European seed weevil (Rhinocyllus conicus) prefer to eat seed heads of musk thistles but will also feed on Canada thistle and bull thistle. A leaf-feeding tortoise beetle (Cassida rubiginosa), accidentally

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Uses of Canada Thistle

N

ative Americans adopted Canada thistle and used it for medicinal purposes to cure mouth diseases. The Chippewa used it as an astringent, tonic, and diuretic. Young shoots and roots may be eaten like asparagus, and the flower’s nectar makes good honey.

introduced in 1902 and established since 1927, defoliates both Canada thistles and bull thistles, but also feeds on artichokes. A root-feeding weevil (Cleonis pigra) and a lace bug (Tingis ampliata) attack artichokes. Two fungal pathogens damage Canada thistle. A widespread rust fungus (Puccinia punctiformis) attacks leaves of the basal rosette and new shoots, causing them to die before flowering. Although introduced into Canada, its success is not yet known. Another fungus (Sclerotinia sclerotiorum) affects the roots.

Selected References “Canada Thistle.” Non-Native Plant Species of Alaska. Alaska Natural Heritage Program, Environment and Natural Resources Institute, University of Alaska, Anchorage, 2006. http://akweeds.uaa .alaska.edu/pdfs/species_bios_pdfs/Species_bios_CIAR_ed.pdf. “Cirsium Genus.” Plant Pest and Health Prevention Services (PHHPS), California Department of Food and Agriculture, 2010. http://www.cdfa.ca.gov/phpps/ipc/weedinfo/winfo_table-commname.htm. “Integrated Pest Management Manual, Thistles.” Explore Nature. National Park Service, n.d. http:// www.nature.nps.gov/biology/ipm/manual/thistle.cfm. McClay, A. S. “Canada Thistle.” In Biological Control of Invasive Plants in the Eastern United States, by R. Van Driesche et al. USDA Forest Service Publication FHTET-2002-04, Morgantown, WV, 2002. http://www.invasive.org/eastern/biocontrol/17CanadaThistle.html. Nuzzo, Victoria. “Element Stewardship Abstract, Cirsium arvense.” Global Invasive Species Team, Nature Conservancy, 1997. http://wiki.bugwood.org/Cirsium_arvense.

n Chinese Lespedeza Also known as: Chinese bush clover, sericea lespedeza, sericea bush clover, silky bush clover, Himalayan bush clover, hairy lespedza Scientific name: Lespedeza cuneata Synonyms: Lespedeza juncea var. sericea, Lespedeza sericea Family: Pea (Fabaceae) Native Range. Eastern Asia, including eastern Russia, Mongolia, northern China, Korea, Taiwan, and Japan. Distribution in the United States. The Great Plains east to the Atlantic and Gulf coasts, from Minnesota to Texas, New York to Florida. Description. Chinese lespedeza is a warm-season perennial herb, with one to several stems that usually grow 3–5 ft. (1–1.5 m) tall, giving it a shrubby appearance. In deep loamy soils, it can reach 6.5 ft. (2 m) in height. Young plants have one stem. More stems develop from the base of older plants, and the stems branch as they grow upward. Stems angle outward, giving the plant a V shape. The round stems have defined ridges covered with bristly white hairs.

350 n FORBS Young stems are light green. Older stems turn brown as they become somewhat woody and fibrous, and may lose the hairs. The compound leaves, alternate on the stem and with very short petioles, are trifoliate, meaning that each leaf has three leaflets, like clover. Each narrow leaflet is 0.2–1 in. (0.5–2.5 cm) long, with smooth margins. Although the tip of each leaflet is rounded, it ends in an awl-shaped sharp point. It is the only species in the Lespedeza genus with a wedge-shaped leaf base. Small flattened hairs, which cover the lower surface of the leaflets, give the leaves a grayish-green to silvery color. Plants have a woody taproot with lateral branches. The taproot may extend 3–4 ft. (1–1.2 m) deep into the soil. From late July to October, two types of flowers grow from leaf axils of the upper or middle leaves of the plant. Chasmogamous flowers, meaning that they open to be cross-pollinated by honeybees and other insects, Several cultivars of Chinese lespedeza were developed and used for appear first, in clusters of 1–4. erosion control in the midwestern and eastern states. (Native range They are typically pea-shaped approximated from USDA GRIN and selected references. Introduced and small, 0.3 in. (0.75 cm), range adapted from USDA PLANTS Database, Invasive Plant Atlas of the creamy white to pale yellow, United States, and selected references.) with purplish throats. The uppermost petal, the banner, is streaked with pink- to purple-colored veins. Cleistogamous flowers, which do not open and are self-fertilized, appear second. They do not have showy petals, and are scattered among the chasmogamous flowers. The numbers of each type of flower, as well as the amount of seed produced, depends on the number of daylight hours, sun or shade location, and air temperatures. More cleistogamous flowers are produced when plants are mowed or grazed. One small shiny seed, which can be tan, olive, purple, or mottled brown, is produced from each flower. The shape and size of the seeds, ellipsoid to oval and slightly flattened, varies according to the type of flower that produced it. Related or Similar Species. The closely related native slender lespedeza, found in a similar range of states, has fewer stems and is a shorter plant, typically growing 2.5 ft. (0.75 m) tall. The stems are covered with fine white hairs. The trifoliate compound leaves are

CHINESE LESPEDEZA n 351

A. Because plants have several stems, they resemble shrubs. B. The three leaflets are slightly hairy on the lower surface (left). C. Chasmogamous flowers are typically pea-shaped. D. Each flower produces one oval seed. (James H. Miller, USDA Forest Service, Bugwood.org.)

supported on 0.5–1 in. (1.3–2.5 cm) petioles, and the glabrous leaflets are as long as 2 in. (5 cm). The flowers are pink, and the base of the banner petal is a deeper rose color. Introduction History. Chinese lespedeza was deliberately introduced into the southern states in the late 1800s for its useful characteristics, including bank stabilization and wildlife cover. The plant was widely recommended in the 1940s by federal and state agencies for erosion control and as a forage and hay crop capable of growing on poor soils. Several cultivars, such as ‘Common Sericea,’ ‘Arlington,’ ‘Serala,’ and ‘Interstate,’ were specifically developed for the midwestern and eastern United States. The plant’s stems, however, are only tender and succulent until they reach 12–15 in. (30–38 cm) tall. Older stems are too woody and coarse to be palatable. Chinese lespedeza seeds, including the cultivars, continue to be available for sale via the Internet. The plant is still used for erosion control along roadsides, around reservoirs, and on strip-mine spoils. It is also used for forage and is still planted as cover for wildlife in some parts of the United States. Habitat. Chinese lespedeza grows in a variety of habitats, including sites where the soil has become severely eroded and sterile and in rough or rocky locations. Because it has been deliberately seeded and cultivated for pasture, it is frequently found in grassy environments, such as meadows, prairies, open woodlands, and savannas. It is also a weed in cultivated crops and fallow fields. It is common in disturbed sites, such as roadsides, railroad tracks, fence rows, trails, burned sites, and any other open disturbed ground that is moist. Plants thrive on bottomland sites, including ditches and wetland borders of ponds and swamps. It can survive flooding in cool water for as long as 10 days, but not in warm water. The plant tolerates light to moderate shade but will not grow in heavy shade. Plants will grow in shallow soil but do best in deep soil, such as organic rich sands, sandy loams, or clay loam. Soils can be either neutral or very acid. Although it is drought tolerant, Chinese lespedeza grows best with annual precipitation of 30–35 in. (75–90 cm), and prefers dry winters and wet summers. Plants survive freezing winter temperatures when dormant, but late spring frosts will damage young growth. Reproduction and Dispersal. Chinese lespedeza reproduces primarily by seed but also vegetatively. Seeds, with no special structure for dispersal, are dispersed when animals and birds eat the fruit and distribute the seeds. Seeds are often contaminants in hay, which is often transported long distances to new locales. Seeds remain viable for 20 years or longer, and the seed bank is extensive. Seeds from chasmogamous, or cross-pollinated, flowers need to be scarified before germination. Optimum temperatures for germination are 68–86ºF (20–30ºC), with a

352 n FORBS variation between day and night. Germination is best when day temperatures are 79ºF (26ºC), night temperatures are 72ºF (22ºC), and days have 13–15 hours of daylight. Although old stems die back to the ground in winter, they may remain standing. New stems sprout every spring from buds on the root crown. A plant can produce 5–30 stems after four years of growth. Root crown buds will be stimulated to sprout after mowing, burning, or grazing. Stems can also grow from lateral buds after mowing or grazing. Impacts. Chinese lespedeza easily escapes cultivation and is an invasive species for many of the same reasons that it was introduced to the United States. It can grow in poor habits of eroded, infertile soils, is resistant to prolonged drought, and is not susceptible to insects or disease. As a long-lived perennial, it provides abundant forage and abundant seed. Beef cattle and goats will eat the new growth, the pliable stems with low tannin content, but they are not appropriate for dairy cattle or hogs. Tannins, which inhibit the growth of other plants, render Chinese lespedeza unpalatable and untouched unless nothing else is available. Tannins are more concentrated in the leaves than in the stems, and also in the upper portions of the plants and in older plants. Other than early in the season when the shoots are tender, it is not important food for wildlife. The plantings at field edges next to wooded areas, however, provide nesting sites for Bobwhite Quail, Grasshopper Sparrow, Meadowlark, and Greater Prairie Chicken. Bobwhite Quail, Wild Turkey, and other gamebirds eat the seeds. Chinese lespedeza is an aggressive plant that invades open areas such as meadows and grasslands in the midwestern and eastern United States. The plants crowd out and suppress native flora, and the tannins have alleleopathic compounds that inhibit growth of nearby native plants. Chinese lespedeza can dominate a grassland community in 3–4 years. Mature plants begin growth earlier in the spring than do most native species. With its large taproot, the species outcompetes native species for water and nutrients, especially in times of drought. Their competitive ability, however, decreases when plants are continually grazed. With a greater number of stems each year, one plant can form a large monospecific stand that can live for more than 20 years. Management. The potential of restoring large areas to a natural state after invasion by Chinese lespedeza is slim, and efforts may take several years. Small infestations have a better chance of being eradicated, although they are difficult to identify and may quickly grow into large stands. Chinese lespedeza is difficult to control in natural areas because digging and mowing cause too much damage to the environment. An integrated management program, which includes burning, mowing, and herbicides, is best. Any infestations are difficult because roadways and erosion-control sites supply a steady seed source. The best control would be to eliminate plant and seed sales. Physical control alone is limited. The depth of the extensive root system makes digging or pulling out plants difficult. Mowing stands low to the ground for 2–3 consecutive years when they are in the flower bud stage will reduce the number of seeds produced and also decrease the vigor of plants. Burning may increase the infestation because it both scarifies seed in the seed bank and creates bare ground for germination. Spring burns stimulate new shoots from the root crown. Late-summer burns, however, will decrease seed production from the current crop. Mowing, which decreases seed production, followed by herbicides on regrowth may be effective. Postemergent chemical treatments can kill mature plants, even the taproot, but they do not affect the seedbank. Herbicides are effective when applied in early to mid-summer, but spraying may need to be repeated for several years. Triclopyr and clopyralid afford the best control but cannot be used in wet sites. Glyphosate is safer for wetlands. Herbicides should be applied while the roots are still increasing reserves, before the plants flower, to be sure

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that the chemicals are carried to the root. One effective integrated method is to spray herbicide on newly sprouting vegetation, burn the remainder, and reseed the area with annual cereal grains or warm season grasses. Chinese lespedeza is not susceptible to 2,4-D, picloram, or dicamba. Biological control is limited. Three-cornered alfalfa leaf hopper (Spissistulus festinus), grass army worms (Pseudodaleta unipuncta), grasshoppers (Schistocerca americana), and lespedeza webworm (Tetralopha scortealis) need further research.

Selected References Hilty, John. “Silky Bush Clover.” Illinois Wildflowers, 2002–2010. http://www.illinoiswildflowers.info/ weeds/plants/silky_bushclover.htm. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Lespedeza cuneata.” ISSG Global Invasive Species Database. 2005. http://www.issg.org/ database/species/ecology.asp?si=270. Remaley, Tom. “Chinese Lespedeza.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2006. http://www.nps.gov/plants/alien/fact/ lecu1.htm. Stevens, Sandy. “Element Stewardship Abstact, Lespedeza cuneata.” Global Invasive Species Team, Nature Conservancy, 2002. http://wiki.bugwood.org/Lespedeza_cuneta.

n Common Mullein Also known as: Big taper, flannel mullein, velvet dock, wooly mullein, Jacob’s staff, flannel leaf, and others Scientific name: Verbascum thapsus Synonyms: None Family: Figwort (Schrophulariaceae) Native Range. Europe and western Asia, from Russia and Afghanistan east through India to southern China. Distribution in the United States. Every state, including Alaska and Hawai’i. Description. Common mullein is an erect biennial herb that grows as tall as 5–10 ft. (1.5–3 m), including the flower stalk. In its first year, the plant grows a rosette of leaves as much as 24 in. (60 cm) in diameter. Rosette leaves are 3–20 in. (8–50 cm) long and 1.5 in. (4 cm) wide. Growth of the rosette continues until stopped by low temperatures in autumn. In the second season, the plant bolts, sending up a strong flowering stem, 1.5–6 ft. (0.5–2 m) tall, which is densely wooly with branched hairs. The stem is longitudinally ridged and covered by overlapping leaves. Stem leaves, oblong to lance-shaped, 4–16 in. (10–40 cm) long and usually 2–4 times longer than they are wide, are alternate or in a loose spiral around the stalk. Leaves are largest at the bottom of the stalk, decreasing with height. Both rosette and stem leaves are bluish gray-green, with a felt-like pubescence which makes then densely wooly and soft. Plants grow both a deep taproot and fibrous lateral roots in the first year. Depth and size of roots vary with location and environmental conditions. Root growth almost ceases when the plant puts its energy into producing the flower stalk. Single flowers, sessile or with very short pedicels, are densely packed on a terminal spike at the top of the leafy stalk. Plants normally have one inflorescence, but it may branch into two or three, especially if damaged. Beginning in June and usually continuing to August or even October, flowers bloom and produce fruit progressively from the base of the inflorescence upward. Flowering period depends on the height of the inflorescence, which can be

354 n FORBS 8–20 in. (20–50 cm) long. The stalk will continue to grow and flower until stopped by cold temperatures in autumn. Flowers are 0.75–1.5 in. (2– 3.8 cm) in diameter and bright sulfur yellow, rarely white, with five round petals that are fused at the base. Stalks, often with fruit attached, remain standing throughout the winter. Fruit are small, 0.25 in. (6 mm), oval two-celled capsules covered with short hairs. They split open when mature to release many tiny brown seeds, which are rough with wavy ridges and deep grooves. Common mullein is monocarpic, meaning that it dies after flowering and maturing fruit. Related or Similar Species. Moth mullen, also called spurious mullein or slippery mullein, is a close relative of common mullein. Also native to Eurasia, it was introduced to the East Coast and was first recorded in Pennsylvania in 1818 and in Michigan in 1840. It can be distinguished from common mulDeliberately brought to the United States in the mid-1700s, common lein by its smaller size, leaf and mullein has a long-standng presence in every state, including Alaska flower details, and lack of hairs. and Hawai’i. (Native range approximated from USDA GRIN and selected The basal rosette is usually 8–12 references. Introduced range adapted from USDA PLANTS Database, in. (20–30 cm) in diameter, and Invasive Plant Atlas of the United States, and selected references.) the flowering stalk is 2–4 ft. (0.6–1.2 m) tall. The largest leaves are 6 in. (15 cm) long by 2.5 in. (6 cm) wide. Leaf margins are toothed and sometimes slightly wavy or irregular. Leaves are hairless, and veins on the upper surface appear wrinkled. The inflorescence is 0.5–2 ft. (0.2–0.6 m) long. Showy flowers, ranging in color from yellow to pinkish white, with a purplish tinge in the center, are less densely packed on the inflorescence than on common mullein. Flowers are not sessile but are borne singly on 0.5 in. (1.25 cm) pedicels. Flower centers have fine purple and white hairs on the stamens. Introduction History. Common mullein was deliberately brought to North America in the mid-1700s by settlers as a fish poison. Crushed seeds placed in the water prevent fish from breathing, allowing easy capture. The plant was first recorded in the Blue Ridge Mountains of Virginia in the 1700s. Because it was used as a fish poison in Europe and also as a medicinal herb, common mullein was probably introduced multiple times. The species has been in

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A. In the first season, plants grow as a rosette. (Forest and Kim Starr, U.S. Geological Survey, Bugwood.org.) B. Fuzzy leaves feel like velvet. (Bonnie Million, BLM, Ely District, Bugwood.org.) C. In the second season, plants bolt and flower. (Karan A. Rawlins, University of Georgia, Bugwood.org.) D. Single flowers are sessile on the stalk. (Steve Dewey, Utah State University, Bugwood.org.) E. Dried fruit capsules split open to release seeds. (Bonnie Million, BLM, Ely District, Bugwood.org.)

the United States so long that it was described as native in an 1818 flora of the East Coast. It spread quickly and was recorded in Michigan by 1839 and was a common weed in Boulder, Colorado, in 1905. The species reached the Pacific coast and became naturalized by 1876. It was first reported in Hawai’i in 1932 and recorded in Alaskan floras by 1968. Habitat. As evidenced by its distribution in both Alaska and Hawai’i as well as throughout the contiguous United States, common mullein has a wide range of environmental tolerances. It prefers disturbed areas with little vegetation, such as neglected meadows and pastures, forest openings, fence rows, roadsides and other right-of-ways, and industrial areas. It can be found in any vegetation type, including prairie, desert, chaparral, and deciduous or coniferous forests. Mullein populations increase as rangeland deteriorates due to heavy grazing, logging, or fires. Even digging by animals can create a small disturbed area suitable for common mullein to invade. An early colonizer, it is often the pioneer species on bare soils. It prefers well-drained, sandy or gravelly soils with a pH of 6.5–7.8, but soil specifics are not important. It is intolerant of shade, but will grow in any open, sunny area. It grows best with annual precipitation of 20–60 in. (50–150 cm) and requires a 140-day growing season. It is found from sea level to 9,000 ft. (2,750 m) elevation, and occasionally higher. Plants vary in size according to climate. Reproduction and Dispersal. Common mullein reproduces solely by seed. Size of the overwintering rosette is important in determining the next season’s flowering. Over 50 percent of rosettes smaller than 6 in. (15 cm) in diameter die over the winter, and rosettes smaller than 3.5 in. (9 cm) fail to flower. Individual flowers open for only a short period, from dawn to midafternoon. If not pollinated by short-tongue or long-tongue bees, the flowers will selfpollinate after they close. Each plant may have 200–300 fruit, with 500–800 seeds per seed capsule, meaning that each plant can produce 100,000–240,000 seeds. Branched inflorescences produce even more. The form of mullein most frequently seen in Hawai’i has a fasciated inflorescence, a twisted and compact irregular growth form, with more flowers and more seed. With no specific adaptations for dispersal, most seeds fall within 3.3–16 ft. (1–5 m) of the parent plant, although some are carried by wind and animals. Seeds are dispersed long distances as contaminants in soil moved for highway or building construction. They have no dormancy requirement and remain viable in the soil for 35–100 years or longer. Seeds in soil

356 n FORBS samples from archaeological sites dated 1300 AD were viable. It is the seed bank, not dispersal, that creates “instant” plants immediately following a disturbance. Seeds germinate faster and seedlings grow more quickly on bare sites. Seeds at or near the surface germinate best, even under diurnal temperature extremes, while those deeply buried do not. Seeds cannot germinate, however, at temperatures below 50ºF (10ºC) or above 104ºF (40ºC). If seed germinates in the fall, the plant becomes an annual and will bolt and flower the following summer. Impacts. Common mullein is rarely a significant weed in natural areas because it is easily outcompeted by native plants. It is incapable of maintaining itself unless the site is repeatedly disturbed. It becomes a problem in bare ground or in soils with little vegetation, and stands can cover acres or miles along a roadway. Plants create a dense ground cover that prevents normal establishment of native species after disturbances. By growing on barren ground exposed by forest fires, for example, common mullein alters the successional sequence. It is eventually outcompeted by shrubs or other native plants in later successional stages because mullein seeds are unable to germinate in the shade. Common mullein, however, has invaded and colonized pristine, undisturbed meadows in the Mono Lake and Owens Valley area of California. It also threatens sparsely vegetated alpine sites on Hawai’ian volcanoes, from sea level to almost 15,080 ft. (4,600 m) on Mauna Kea. In 1990, the plant covered 770 sq. mi. (2,000 km2) in Hawai’i. It is found in several undisturbed mountain communities, including subalpine grasslands dominated by alpine hairgrass, subalpine ohia lehua woodlands, as well as in alpine desert communities. The many bare sites on volcanic soils are favorable to common mullein, and preferential grazing of other plants by feral sheep and goats have probably helped it to spread. It inhibits revegetation by native Hawai’ian species and specifically replaces the endangered silversword. Common mullein is not a weed in agricultural crops because it does not survive repeated cultivation. It is a host, however, for insect pests, such as the mullein leaf bug, which attacks apples and pears in eastern states. Management. Because common mullein is primarily a weed of bare soil surfaces, maintenance of native plant cover or sowing bare sites with native plant seeds may prevent establishment. Its abundant seed production makes it difficult to totally eradicate. Any physical control should minimize disturbance to the soil surface. Regular cultivation, such as disking or plowing, however, controls infestations because it continually uproots seedlings. Plants can be hand-pulled before seed sets, but stalks, flowers, and seeds should be bagged to prevent seed dispersal. Plants cut below the lowest leaves will not resprout. Mowing is ineffective because the cuts are too high and the rosettes continue to grow. When mowing ceases, plants bolt to flower. If only the flower stalk is cut, it will branch new stalks. Burning kills both rosettes and bolted plants but, unless done selectively with a flamethrower, creates bare soils that enhance more germination. Grazing is not an option because cattle and sheep avoid the unpalatable hairy leaves, and livestock trampling exposes bare soil. Applications of systemic herbicides, such as glyphosate or triclopyr, provide effective chemical control as long as a surfactant is added to help the herbicide penetrate the thick hairs on leaf surfaces. To prevent damage to nontarget plants, applications are best done in early spring before native species break dormancy. Chemical applications are appropriate on steep slopes or otherwise inaccessible areas or where physical removal would cause too much soil disturbance. Herbicides do not need to be applied to the entire plant. Application to the growing point in the center of the rosette is sufficient. Preemergent herbicides are an option to control germination from the seed bank, but their application also destroys seeds of desirable plants.

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Medicinal and Other Uses of Common Mullein

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ommon mullein has had many uses in Europe. The yellow flowers were used for a hair dye as early as the fourth century BC. Aristotle recorded its use as a fish poison, and Romans used the stalks, dipped in tallow, for torches. Plant parts have been an herbal medicine for respiratory ailments, such as asthma, tuberculosis, bronchitis, coughs, colds, congestion, and pneumonia. It was used as a remedy for urinary tract infection, skin disease, hemorrhoids, diarrhea, burns, earaches, warts, migraines, frostbite, and ringworm. Native Americans readily adopted the plant. Hopi in Arizona smoked dried leaves and flowers, combined with other plants, to treat mental illness. Other tribes in the Midwest and East smoked the herb to treat respiratory problems, and concocted a cough syrup from boiled roots. Mashed leaves were used as a poultice for bruises, wounds, sprains, and headaches. The plant remains useful today. A methanol extract is used against mosquito larvae, and the plant contributes to herbal eardrops for children’s earaches. Recent studies have shown that mullein has antibacterial and antitumor properties.

Two insects from Europe offer possible biological control. Maturing larvae of a hostspecific curculionid weevil (Gymnaetron tetrum), which was accidentally introduced to North America sometime before 1937, eats seed capsules. Although the larvae can destroy 50 percent of a plant’s seeds, the weevil fails to limit the plant because of the number of seeds produced. The mullein moth (Cucullia verbasci), which makes only limited use of native species, has been tested in the United States. Two diseases, powdery mildew (Erysiphe cichoracearum) and root rot (Phymatototrichum omnivorum), attack mullein, but also affect commercial crops, including vegetables and cotton.

Selected References Gucker, Corey L. “Verbascum thapsus.” In: Fire Effects Information System, USDA, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, 2008. www.fs.fed.us/database/feis/plants/ forb/vertha/all.html. Hoshovsky, Marc C. “Element Stewardship Abstract, Verbascum thapsus.” Global Invasive Species Team, Nature Conservancy, 1986; modified 2009. http://wiki.bugwood.org/Verbascum_thapsus. “Moth Mullein: Verbascum blattaria.” Virginia Tech Weed Identification Guide, n.d. http://www .ppws.vt.edu/scott/weed_id/vesbl.htm. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Verbascum thapsus.” ISSG Global Invasive Species Database, 2005. http://www.issg.org/ database/species/ecology.asp?si=695&fr=1&sts=sss&lang=EN. Pitcairn, Michael J. “Verbascum thapsus L.” In Invasive Plants of California’s Wildlands. edited by Carla C. Bossard, John M. Randall, and Marc C. Hoshovsky. Berkeley: University of California Press, 2000. http://www.cal-ipc.org/ip/management/ipcw/pages/detailreport.cfm@usernumber=87&survey number=182.php. Remaley, Tom. “Common Mullein.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2009. http://www.nps.gov/plants/alien/fact/ veth1.htm.

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n Common St. Johnswort Also known as: Klamath weed, St. John’s wort, common goatweed, tipton weed Scientific name: Hypericum perforatum Synonyms: None Family: Mangosteen (Clusiaceae) Native Range. Europe, the Canary Islands, North Africa, and Asia, including aouthwestern Asia, western Russia, Mongolia, and as far east as the China coast. Distribution in the United States. Every state except Florida, including Alaska and Hawai’i. Most problematic in the northern states. Description. Common St. Johnswort is an erect perennial herb, with one stem or multiple stems, that grows 1–4 ft. (0.3– 1.2 m) tall. Most branching is toward the top of the plant. Stems emerging from the lower leaf axils are short, 0.8–4 in. (2–10 cm), and sterile. The reddish or rust-colored stems are woody at the base. Although the stems are smooth, two longitudinal ridges, which are covered with black glands, make the stems two-sided. The sessile leaves, opposite on the stem, are narrow and lanceshaped, 1–2 in. (2.5–5 cm) long, with pointed tips. The green leaves are covered with tiny translucent glands, which can be seen when the leaf is held to the light. These glands contain hypericin, a toxic substance. Leaf margins are slightly rolled under. The plant has a complex root system with a long, stout taproot. Many branching lateral roots grow from the taproot, as deep as 5 ft. (1.5 m). Rhizomes, extending from the root crown, grow just below the soil surface. New shoots in the spring emerge both from the root crown and Common St. Johnswort is often found along roadsides and in other disturbed from the rhizomes. From June to September, ground and waste areas. (Native range adapted from USDA GRIN and selected references. Introduced range adapted from USDA PLANTS bright yellow star-like flowers, Database, Invasive Plant Atlas of the United States, and selected references.) 0.75–1 in. (2–2.5 cm) in diameter,

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A. The top of the stem may have several branches. (Eric Coombs, Oregon Department of Agriculture, Bugwood.org.) B. Showy yellow flowers have many stamens. (Richard Old, XID Services, Inc., Bugwood.org.) C. Margins of the lance-shaped leaves are slightly inrolled. (Steve Dewey, Utah State University, Bugwood.org.) D. Fruit are clustered at the ends of stems. (Steve Dewey, Utah State University, Bugwood.org.)

grow in flat-topped clusters of 25–100. Each flower has five petals, sometimes with tiny black dots and edges, and many yellow stamens. Fruit, a rust-brown three-part oval pod, less than 0.4 in. (1 cm) long, matures at the end of August. The capsule, which has no lobes, opens to release many shiny dark brown seeds. Aerial parts of the plant turn rusty red in fall, and the dead stalks may remain standing through the winter or for several years. Related or Similar Species. Canary Island St. Johnswort is an ornamental shrub, 13–16.4 ft. (4–5 m) tall, with narrow leaves, 0.75–2.75 in. (2–7 cm) long. Its yellow-orange flowers are 0.5 in. (1.5 cm) in diameter, and the sepals are lined with hairs. The seed capsules are leathery. A relatively recent invader in coastal California, its impacts are not yet fully known. Several species of Hypericum are native to the United States. Dwarf St. Johnswort, found growing in moist places such as riparian habitats, is an erect annual or perennial herb that is usually 2 ft. (0.6 m) tall. Its stem is four-angled. Flowers are small, less than 0.25 in. (0.6 cm) across, and the fruit is a single-cell capsule. Large St. Johnswort, an annual that grows in moist sandy soil, has tiny flowers, linear leaves, and a one-compartment capsule. Tinker’s penny is also an annual herb in wet places, growing prostrate, less than 1 ft. (0.3 m) tall. Native species do not produce hypericin. Introduction History. Currently cultivated in farms in Eastern Europe, common St. Johnswort has been used medicinally for centuries. It was brought to the United States in the seventeenth century by Rosicrucians, a group also known as the Ancient Order of the Rosy Cross, which believes in mysticism and metaphysical connections. The plant escaped from gardens, and by the Revolutionary War, it was common along roadsides from Maine to Florida. Common St. Johnswort was introduced to California around 1900, and by 1940, about 7.5 million ac. (3 million ha) of rangelands in California and the Pacific Northwest were infested. Habitat. St. Johnswort grows best in temperate climates with dry summers and cool, moist winters. The plant thrives in poor, dry soils in full sun and does not tolerate saturated

360 n FORBS soils. It prefers coarse textured, gravelly or sandy soils, including sand dunes, and grows in a wide range of acidity, pH 4.3–7.6. Common in waste areas and disturbed ground, initial infestations are often associated with logging, fire, mining, or overgrazing. Plants also grow in road and railroad right-of-ways and even in sidewalk cracks. The plant spreads from those disturbed areas to natural open forests, healthy rangelands, meadows, dry pastures, and fields. Reproduction and Dispersal. Common St. Johnswort reproduces both sexually and vegetatively. Plants usually do not flower in their first year of growth. Flowers are both insect pollinated and apomictic (needing no pollination). Every year, each plant typically produces 15,000–33,000 seeds, which are viable for 6–10 years. Wind, water, and animals carry seeds long distances. The seed coat is gelatinous, allowing it to adhere to fur, feathers, clothes, vehicle tires, and machinery. Seeds can also be transported in contaminated hay. After 4–6 months of dormancy, needed to break down the seed coat, seeds germinate from fall to spring. They do best at temperatures 70–78ºF (21–25.5ºC) and on bare soil in full sun after a heavy rain. Fire temperatures of 212–284ºF (100–140ºC) frequently stimulate more seeds to germinate. Seedlings, however, grow slowly and are poor competitors with established native grasses and other plants. Buds on underground rhizomes and above-ground creeping stems may sprout and grow roots. Independent plants subsequently separate from the parent. Vegetative propagation is stimulated by mowing, grazing, or burning. Impacts. By creating a dense canopy of vegetative growth early in spring, common St. Johnswort shades out and displaces native plant species, which reduces forage for livestock and wildlife. Because they grow on disturbed sites, plants disrupt succession and delay establishment of native species. Although not palatable and only grazed when little else is available, all parts of St. Johnswort are low to moderately toxic when eaten by livestock. The plant is toxic at all stages of growth. The toxins remain active in dried plants and may be a contaminant in hay or processed food. The toxin is absorbed in the intestinal tract, enters general circulation, and is carried to the skin, where it is activated by ultraviolet rays. Sunlight reaching the animal is abnormally converted into heat, causing sunburn, which damages cells. Skin may become swollen and tender before turning red, and may be so badly burned that it peels off in sheets. It also causes inflammation of mucus membranes, resulting in swelling, blisters, and open sores, with a risk of infection. Other symptoms may include itching, fever, rapid pulse, and diarrhea. It is especially toxic to cattle and sheep, but also to goats, horses, and swine. It primarily affects areas with light pigmentation, such as pink or white skin, udders and teats, and the delicate tissue around the mouth and eyes. Parts of the body that receive more sun, such as head, neck, and back, are also affected. Poisoning can develop after the animal has consumed 1–4 percent of its body weight or eaten it for 4–5 days. Animals will act abnormally, and pain may prevent them from eating or drinking. Inflammation in the eyes may affect vision. Although moving affected animals into shade will be sufficient for mild cases, severe cases, including damaged eyes or blistered skin, require veterinary care, including antibiotics or other medication. Although rarely resulting in death, the toxin causes economic losses. The accumulation of standing dry stalks presents a fire hazard in late summer and fall. Management. Common St. Johnswort is difficult to eradicate because of its extensive root system and abundant seeds. Maintaining rangeland in good condition will help to prevent its encroachment. Although it must be ingested to affect animals, workers should wear gloves

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St. Johnswort in Medicine

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he plant has been used for centuries in Europe for various ailments. It was a treatment for wounds, an astringent, a sedative, and a diuretic. It was also used to treat hysteria. The toxin, hypericin, in St. Johnswort is an antidepressant ingredient in herbal medicine. Research using lab animals has indicated that hypericin was effective in treating several viruses, including herpes and hepatitis B. In 1991, studies were begun to test the effectiveness of very high doses of hypericin against human immunodeficiency virus (HIV). The trial was aborted, however, when the patients became very sensitive to sunlight and developed skin rashes. One darkskinned patient, however, was not affected. Because limited studies indicate that St. Johnswort extracts interact with other medications, further research should proceed cautiously.

and avoid touching their eyes while removing common St. Johnswort because contact with the plant may cause skin blisters on sensitive persons. Physical control, such as tilling or mowing, will limit seed production but stimulate vegetative reproduction and new growth. Burning will stimulate both seed germination and sprouting of root buds. Repeated tillage may be effective in agricultural fields, but may also spread root fragments. New plants or small infestations can be effectively pulled by hand, providing that the entire plant, including the root system, is removed. All plant parts and seeds must be disposed of offsite because they can sprout. Large stands may be mowed, sprayed with herbicides, and reseeded to improve pasture. The waxy leaves limit the uptake of chemical applications. St. Johnswort can be temporarily suppressed in pasture and rangeland by several herbicides, including aminopyralid, metsulfuron, picloram, and 2,4-D. Each type is effective during a different stage in the plant’s life cycle. Herbicides, however, often increase the palatability of St. Johnswort and exacerbate the problem of toxicity. St. Johnswort was the first weed to be targeted for biological control in the United States. After being released in California in 1945 and 1946, two foliage beetles (Chrysolina hyperici and C. quadrigemina), became established in two years. The larvae, feeding on leaves and flowers, can completely defoliate plants. Although the beetles have reduced infestations by 97–99 percent, new outbreaks can occur locally following logging, fire, or some other type of disturbance. In 1950, a root-boring beetle (Agrilus hyperici) was released. Larvae feed on roots for almost a year, stunting plants and reducing flowering. The California colonies of beetles became the source for further collection and release elsewhere. Those insects, however, do not thrive at high elevations or in cold climates. The larvae of a moth (Aplocera plagiata), more recently released and established, eats leaves and flowers, defoliating plants and inhibiting seed production.

Selected References “Common St. Johnswort.” Non-Native Species of Alaska. Alaska Natural Heritage Program, Environment and Natural Resources Institute, University of Alaska, Anchorage, 2005. http:// akweeds.uaa.alaska.edu/pdfs/species_bios_pdfs/Species_bios_HYPE.pdf.

362 n FORBS “Common St. Johnswort or Klamathweed.” Plant Pest and Health Prevention Services (PHHPS), California Department of Food and Agriculture, n.d. http://www.cdfa.ca.gov/phpps/ipc/weedinfo/ hypericum.htm. “Fact Sheet 729, St. Johns Wort (Hypericin).” AIDS InfoNet, New Mexico AIDS Education and Training Center, Health Sciences Center, University of New Mexico, 2009. http://www.aidsinfonet.org/fact _sheets/view/729. Goetz, Rebecca J., Thomas N. Jordan, John W. McCain, and Nancy Y. Su. “Common St. Johnswort, Klamath Weed.” Cooperative Extension Service, School of Veterinary Medicine, Purdue University, West Lafayette, IN, n.d. http://www.vet.purdue.edu/toxic/plant38.htm. Jacobs, Jim. “Ecology and Management of Common St. Johnswort (Hypericum perforatum L.)” Natural Resources Conservation Service, Invasive Species, Technical Note No. MT-14, U.S. Department of Agriculture, Montana, 2007. http://www.mt.nrcs.usda.gov/technical/ecs/invasive/technotes/invasi vetechnotemt14/.

n Dyer’s Woad Also known as: Marlahan mustard Scientific name: Isatis tinctoria Synonyms: None Family: Mustard (Brassicaceae) Native Range. Grasslands and desert regions of Central Asia, especially the Caucasus region. Possibly western China, western Tibet, and Afghanistan. Widespread in Europe. Distribution in the United States. Eastern states, from New York south to Virginia, Illinois and Missouri in the Midwest, and from the Rocky Mountains west to the Pacific coast. Description. Usually a biennial, dyer’s woad may also be a short-lived perennial or a winter annual. Either the seed or the rosette must undergo a period of cold temperatures before the plant can flower. Most germination occurs in spring. The plant grows a basal rosette of leaves and overwinters. In its second spring, the plant bolts, sending up flower stalks that are 1–4 ft. (0.3–1.2 m) tall. If conditions are poor in the second season, the plant can continue growing as a rosette for a third year. A few seeds, however, germinate in the fall and live as annuals, flowering and producing seed the following spring. Leaves, both basal and stem, are bluish green, with a prominent cream-colored midrib from base to tip. The basal rosette leaves, oblong or lance-shaped, 2–8 in. (5–20 cm) long, are slightly succulent. They have small, rounded teeth and are covered with fine hairs, especially along the midrib. Broad at the tip, the leaves narrow toward the base, grading into a short petiole. Leaves on flowering stems are smaller, lance shaped, and glabrous, with entire margins. They are sessile, in an alternate arrangement, and the lower part of the leaf clasps the stem with auricles. The plant has a thick taproot, 3–5 ft. (1–1.5 m) long. Lateral roots, that grow in the top 12 in. (30 cm) of soil, branch during the second season. Plants may have as many as 20 flowering stems. Most flower stems grow erect from the base, but the lower branches are decumbent, paralleling the ground and turning up at the tips. The tiny yellow flowers, 0.25 in. (0.6 cm) in diameter, grow in flat-topped, elongated clusters on branched racemes. Typical of the mustard family, they have four narrow petals that form a cross. Flowers are showy, crowded on both the plant and the stems. Flowers will be blooming at the top of the raceme, while seeds are developing below. The winged fruit is a narrow, flattened pod (silicle), 0.5–0.75 in. (1.2–2 cm) long and 0.25 in. (0.6 cm) wide, with the tip slightly wider than the base. Pods, which hang down from the stalk on short pedicels, are green and hairless when young, but become black or dark purplish brown as they mature. Pods are indehiscent and cling to the stem. Each pod has one

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brownish-yellow cylindrical seed, 0.1 in. (3 mm) long. Fruit matures in late spring to early summer, and plants die after they produce seed. Related or Similar Species. Although many mustard species have showy yellow flowers, none have a similar accumulation of black seed pods lining the old flower stems. Introduction History. Dyer’s woad was brought to colonial Virginia in the late seventeenth century, where it was cultivated for blue dye. It is a more recent invader of western states, introduced in the early 1900s in contaminated alfalfa seed, both to northern California and to Utah. In 1934, a specimen was noted in the pharmaceutical garden at the University of Montana, and by 2006, dyer’s woad infested at least 12 counties in that state. The first identification in Washington, in 1986, was along a railroad. Although that stand was eradicated in 1992, the site is still monitored. The plant has the capacity to continue expanding By reducing forage for livestock, dyer’s woad threatens pastures and rangeland in western states. (Native range approximated from USDA its range in the United States. Habitat. Although dyer’s GRIN and selected references. Introduced range adapted from USDA woad can infest both disturbed PLANTS Database, Invasive Plant Atlas of the United States, and selected references.) and undisturbed communities, it is often found in rugged, inaccessible terrain that is usually gravelly, rocky, or sandy. The plant will also grow in loose alkaline soil, and its long taproot enables it to thrive in the arid steppe regions of the West. The species requires little nitrogen and can thrive on nutrient-poor soil. Woad may first appear in gravel pits and waste areas, or along road, levee, and railroad right-of-ways, before spreading into well-vegetated rangeland, pasture, forest, and wildland. Plants may also invade row crops and orchards. They can grow at 3,000–8,000 ft. (1,000–2,500 m) elevation, usually in full sun. Reproduction and Dispersal. Rosettes grow quickly after snowmelt, and seeds develop 4–8 weeks after the flower stalks begin to grow. Each plant usually produces 350–500 seeds. About 95 percent of the indehiscent seed pods fall to the ground within 2 ft. (0.6 m) of the parent plant, but the winged pods may be blown several feet, especially over a snow crust.

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A. Dyer’s woad is bushy with tall flowerstalks. B. Fine hairs highlight the midribs on the basal rosette leaves. C. Each seed pod has one seed. D. Flowering stem, immature green seed pods, and mature black pods. (Steve Dewey, Utah State University, Bugwood.org.)

Seeds may be transported long distances along roads, trails, or railways. The pods float in water, and seeds may be carried by animals, both attached to fur and within the gastrointestinal tract. Seeds may be a contaminant in crop seeds, livestock bedding, or in hay or other livestock feed. Most seeds are viable for only a short term, but intact pods that are buried in the soil may remain viable for 10 years. Seed pods contain a water-soluble chemical that inhibits germination, and seeds remain in the seed bank until rainfall is sufficient to wash it away, ensuring that the seedling has enough moisture for growth. Spring germination may be more common than fall germination because melting winter snows leach the chemical out of the seed. Seeds germinate under a wide range of temperature, 37–77ºF (3–25ºC). Although the root crown has dormant buds that can sprout if the top part of the plant is damaged, plants do not reproduce vegetatively. Impacts. The biggest threat of dyer’s woad is to rangelands and pastures, where it can form dense infestations, outcompete native plants, and reduce forage. It grows rapidly, outcompeting native plants for spring moisture. Currently infesting thousands of acres of western rangeland, dyer’s woad lowers the quality and capacity of rangeland. It has been estimated to reduce grazing capacity of range by 38 percent. It also competes with crops, costing millions of dollars in diminished crop yields. Although sheep will eat the young rosettes when nothing else is available, dyer’s woad is unpalatable to livestock. An accumulation in the soil of the chemical which inhibits dyer’s woad germination may be alleleopathic to other species, but it is not toxic to animals. Management. At least in some areas of the western states, dyer’s woad appears to be in the introductory stages of invasion. The goal is to eradicate it before it spreads further, and any method must be repeated because seeds are persistent in the seed bank for several years. Physical control can be accomplished by intensive labor of hand-pulling or digging out plants, including the taproot and root crown, because latent buds on the root crown will sprout. Because fewer than 25 percent of young rosettes survive, compared with 80 percent of mature rosettes, removal efforts should be concentrated on mature rosettes and flowering plants, after plants have bolted but before seed is produced. Removing young rosettes would duplicate their natural mortality. Hand-pulling, however, should be repeated in 3–4 weeks to remove the later-maturing plants. Hand removal may be the only method possible on difficult terrain. Because even green pods may set seed, all pods on plants should be burned or removed to a landfill. Cropland may be kept free of dyer’s woad by a combination of tilling,

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Successful Eradication—but a Lot of Work!

V

olunteer labor from the Montana Dyer’s Woad Cooperative Project, which was established in 1984, had, by 2007, significantly reduced the dyer’s woad population in that state, from 13 infested counties down to 4, and from 480 ac. (194 ha) down to 6.4 ac. (2.6 ha). After eight years of volunteer labor in Utah, a population of woad was reduced by 95 percent. Source: Jacobs and Pokorny, 2007.

crop rotation, and herbicides. Tilling in spring will kill new seedlings and rosettes. Seedlings that emerge in summer or fall cannot flower and produce seed until they undergo a cold period. Those seedlings can be tilled or sprayed with herbicide. Mowing plants in orchards, if repeated when new stems sprout from the root crown, will prevent seed development. Although sheep may eat the young rosettes in early spring when nothing else is available, grazing offers little control. The choice of chemical treatments is dependent on the plant’s stage of growth. Applications of metsulfuron or chlorsulfuron effectively prevent seed production when applied to stems in the late bloom stage. Imazapic may also be applied to bolting rosettes. Limiting seed production will decrease the number of rosettes the following spring. The most effective herbicide on the seedling to rosette stage is 2,4-D, but it does not control the plant after flowering begins. The only known biological control is a rust fungus thought to be Puccinia thlaspeos, a native to Eurasia. First discovered in southern Idaho in 1978, it has since spread to other states. It is a systemic, entering the plants through leaves. Although it takes 3–9 months for the plant to succumb, the rust kills seedlings and young rosettes and completely prevents seed production on most infected plants. It has spread naturally to new populations, and deliberate transfer is being investigated.

Selected References “Dyer’s Woad.” Weed of the Week. U.S. Department of Agriculture, Forest Service, Invasive Plants, 2006. http://www.invasive.org/weedcd/pdfs/wow/dyers_woad.pdf.

Uses of Dyer’s Woad

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yer’s woad has long been used for dye and medicine. It was cultivated as a source of blue dye in Europe until it was replaced in the 1600s by indigo from the East Indies. Cultivation ceased in England in 1930. The source of the blue dye is indigotine, present in the leaves and extracted through a fermentation process. Although woad has a history of medicinal use, and may hold promise for future treatments, no clinical trials have been conducted regarding its safety. Root extracts are a rich source of the anticancer chemical glucobrassicin. Plant parts have been used in Chinese medicine for a wide variety of ailments, including throat infections, mumps, encephalitis, gastroenteritis, hepatitis, headaches, and fever. Chinese studies indicate that dyer’s woad is antibacterial, antiviral, and antiparasitic.

366 n FORBS “Dyers Woad (Isatis tinctoria L.).” Written Findings of the State Noxious Weed Control Board—Class A Weed, State of Washington, 1999. www.nwcb.wa.gov/weed_info/Written_findings/Isatis_tinctoria.html. Jacobs, Jim, and Monica Pokorny. “Ecology and Management of Dyer’s Woad (Isatis tinctoria L.).” Invasive Species Technical Note No. MT-10. Natural Resources Conservation Service, U.S. Department of Agriculture, 2007. Roberts, Teresinha. “Woad Facts.” 2010. http://www.woad.org.uk/html/woad_facts.htm.

n Fig Buttercup Also known as: Lesser celadine, pilewort, bulbous buttercup, small crowfoot Scientific name: Ficaria verna Synonyms: Ranunculus ficaria, Ficaria ranunculoides Family: Buttercup (Ranunculaceae)

Ornamental varieties of fig buttercup are sold by many plant nurseries throughout the country. (Native range adapted from USDA GRIN and selected references. Introduced range adapted from USDA PLANTS Database, Invasive Plant Atlas of the United States, and selected references.)

Native Range. Europe, northern coast of Africa, and western Russia. Distribution in the United States. Upper midwestern and northeastern states, from Wisconsin east to New Hampshire, south to Virginia, and west to Missouri, Illinois, and Texas. Also in Oregon and Washington. Description. Fig buttercup is an herbaceous perennial plant with a short life cycle, growing in late winter and spring. The species has variable morphology due to several cultivars and varieties. Shiny, darkgreen leaves begin to emerge in winter, forming a lowgrowing basal rosette. Depending on the variety or subspecies, plants are either erect or reclining, 4–12 in. (10– 30 cm) tall. The tender, fleshy leaves, supported by long petioles, are kidney- to heartshaped, 0.7–2 in. (1.8–5 cm) in both length and width. Leaf tips are rounded, and margins are usually entire or wavy. The glabrous, fleshy stems have closely spaced nodes where bulblets may develop. The root system is both fibrous and tuberous. The leaves

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A. Butter yellow flowers bloom in early spring. B. Edges of the heart-shaped leaves may be wavy. C. New sprouts grow from clusters of tubers. (Leslie J. Mehrhoff, Ecology and Evolutionary Biology University of Connecticut, Bugwood.org.)

and flower stalks grow from a cluster of tubers. Many turions, which are young scaly shoots, grow on the roots. Plants flower in late winter or early spring, March to May, with one terminal flower on each stem. The delicate flower stalks grow taller than the leaves of the plant. More flowers are produced in high light conditions and on plants with larger tubers. The flowers are symmetrical, about 1 in. (2–3 cm) in diameter with 8–12 glossy yellow petals. They are slightly darker in the center and fade to white as they age. In May, each flower may produce a globular fruiting head, about 0.25 in. (0.6 cm) in diameter, composed of several pubescent achenes (dry, one-seeded fruits). After flowering, plants die back, and by early June, most are dormant, reduced to thick tubers in the ground. Related or Similar Species. At least nine cultivars and 100 varieties of fig buttercup have been developed, including a double-flower form. Some varieties have leaves with silvery or whitish mottling or black spots. Most buttercup species have upright stems, while fig buttercup may have either upright or decumbent stems, meaning that the stems lie parallel to the ground, but with the tip upright. Marsh marigold, native to wetlands in eastern United States, is a more robust plant with larger, lighter green leaves. Its flower stalks, at least 8 in. (20 cm) tall, grow upright and support a number of flowers. It has no petals, but the 5–9 sepals are a deep yellow and resemble petals. The fruit is a follicle or dry seed pod. Marsh marigold produces no tubers or bulblets and never grows as a continuous carpet. Celandine, also called greater celandine, grows much taller and has distinctly lobed leaves. Celandine poppy is a tall native perennial with a hairy stem and deeply lobed, large leaves. Both plants are in the poppy family and have flowers with four petals. Ground ivy, also known as gill-over-the-ground and creeping Charlie, is a creeping perennial groundcover in the mint family. It is distinguished from fig buttercup by having hairy leaves and lavender asymmetrical flowers. Introduction History. Fig buttercup was introduced to the eastern United States as an attractive ornamental, probably in the mid-1700s. Many varieties are widely available from nurseries, catalogs, and Internet sales. Habitat. Fig buttercup grows best in the moist alluvial soil of herbaceous wetlands and forested floodplains, where it forms large dense patches that carpet the ground. It also occupies some upland sites, including grassy meadows and early successional forests. The species is less frequently found in drier soils, such as embankments, roadsides, and open woodlands. Although it may tolerate dry sites during summer dormancy, seasonally wet

368 n FORBS areas provide plants with moisture in the spring when they are actively growing. In the same manner, it grows in sunny sites in wooded areas in spring, but is dormant in summer when the canopy provides shade. It also grows in disturbed sites, such as abandoned fields, pastures, roadsides, and vacant lots, and is a weed in gardens and lawns. Some evidence exists that fig buttercup prefers sandy and slightly alkaline soil. Reproduction and Dispersal. Although each flower may produce 10–15 achenes, fig buttercup seeds are rare because most abort before reaching maturity. Approximately 60 percent of seeds that are produced are viable. No information is available regarding a seed bank. Most reproduction is vegetative, by tubers and bulblets. Small cream-colored bulblets, each of which can produce a new plant, grow in stem axils or nodes. Plants have many fleshy, fingerlike tubers with several turions, meaning shoots that are ready to develop new plants. Tubers and turions survive for years and are easily transported. Tubers may be uprooted and scattered by digging or burrowing animals. Tubers may also be dispersed in floodwaters or as a contaminant in transported soil, or by human activity, such as weed-pulling or deliberate planting. Impacts. Fig buttercup is an aggressive plant that spreads rapidly, creating monocultures that cover acres of ground. Plants begin growth early in spring, in sunlight before the leaf canopy of trees and shrubs develops. Because fig buttercup emerges first and is a vigorous spring grower, it displaces native plants, especially those with a spring-flowering life cycle, including but not limited to bloodroot, wild ginger, spring beauty, harbinger-of-spring, twinleaf, squirrel-corn, trout lily, trillium, and Virginia bluebells. As a result, the structure of the native community is altered. These native spring ephemerals are important sources of nectar and pollen for native pollinators, such as bees, small beetles, and flies. These native plants also produce fruit and seeds, which are food for native species of insects and other wildlife. Management. Fig buttercup’s abbreviated life cycle allows management opportunities in only a short window of time when it is growing. Because it is difficult to remove all bulblets and tubers, physical control, such as pulling or digging out plants, is practical only on small infestations. Such methods also cause soil disturbance, which creates sites for more invasion. Chemical treatment is preferable for controlling or eradicating fig buttercup. Glyphosate, a systemic herbicide, will kill tubers, but the treatment should be repeated the following year. Herbicides should be sprayed on the leaves in late winter or early spring, either before plants flower or when approximately 50 percent of plants are in the bloom stage. Spraying before native ephemerals begin to grow ensures that few to no desirable plants will be damaged. Native amphibians, such as frogs and salamanders that can absorb toxins through their skin, are also less likely to be harmed by early spring applications of herbicides because they have yet to come out of hibernation. No biological controls are known or are being investigated.

Selected References “Fig Buttercup.” Invasive Plant Atlas of New England (IPANE), University of Connecticut, 2009. http:// nbii-nin.ciesin.columbia.edu/ipane/icat/browse.do?specieID=89. Huebner, Cynthia, Cassandra Olson, and Heather Smith. “Lesser Celadine.” Invasive Plants Field and Reference Guide: An Ecological Perspective of Plant Invaders of Forests and Woodlands-Supplement 2. USDA Forest Service, State and Private Forestry Technical Publication 05-04, 2008. http:// na.fs.fed.us/pubs/misc/ip/ip_field_guide_supp2_lr.pdf. “Lesser Celandine.” Oregon Department of Agriculture Plant Division, Noxious Weed Control, n.d. http://www.oregon.gov/ODA/PLANT/WEEDS/profile_lessercelandine.shtml. Swearingen, Jil.“Fig Buttercup.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2010. http://www.nps.gov/plants/alien/fact/ rafi1.htm.

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n Garlic Mustard Also known as: hedge garlic, sauce-alone, jack-by-the-hedge, poor-man’s mustard Scientific name: Alliaria petiolata Synonyms: Alliaria officinalis, A. alliaria, Sisymbrium alliaria, S. officinalis, Erysium alliaria Family: Mustard (Brassicaceae) Native Range. Southern Europe, northern Africa, and western Russia. Possibly Southwest Asia as far east as India and western China. Distribution in the United States. Most abundant in the Midwest and New England, from North Dakota east to Maine, south to Georgia, and west to Oklahoma, Colorado, and Utah, and the Northwest coast. Also in Alaska. Description. Garlic mustard, so named because the dark green leaves emit a garlic smell when crushed, is a biennial herb, meaning that it has a two-year life cycle. In the first year, the plant grows a low rosette of leaves, 4 in. (10 cm) tall and 2.4–4 in. (6–10 cm) in diameter by fall. The plant remains green and continues to grow in winter during snowfree periods when temperatures are above freezing. In the second summer, plants send up a flowering stem, 2–3.5 ft. (0.6– 1 m) tall. First-year leaves are round to kidney-shaped, 2.4–4 in. (6–10 cm) in diameter, with scalloped edges. The alternately arranged stem leaves are triangular or heart-shaped, 1.2– 3.2 in. (3–8 cm) both long and wide, and coarsely toothed. They become gradually smaller toward the top of the stem. All leaves grow on pubescent petioles, 0.4–2 in. (1–5 cm) long. Plants usually have one or two flowering stems, with few or no branches. Small white flowers, Garlic mustard grows in a number of habitats, which vary according to 0.3 in. (7 mm) in diameter, geographic region. (Native range adapted from USDA GRIN and appear in late April and May. selected references. Introduced range adapted from USDA PLANTS Flowers, in button-like clusters, Database, Invasive Plant Atlas of the United States, and selected usually grow on a terminal references.)

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A. Flowering stems may be more than 2 ft. (0.6 m) tall. (Chris Evans, River to River CWMA, Bugwood.org.) B. The four petals of each flower form a small cross. (Chris Evans, River to River CWMA, Bugwood.org.) C. Rosette leaves are distinctly kidney-shaped. (Ohio State Weed Lab Archive, The Ohio State University, Bugwood.org.) D. Triangular stem leaves have pointed tips. (Linda Haugen, USDA Forest Service, Bugwood.org.) E. Fruit are very slender seed pods. (James H. Miller, USDA Forest Service, Bugwood.org.)

raceme, but they can also occur on short racemes in leaf axils. The four narrow petals form the shape of a cross. Fruit, which develops in May and June, is a four-sided slender pod called a silique, 1–2.5 in. (2.5–6.3 cm) long. Siliques, averaging 9–19 per plant, grow erect on short, stout pedicels 0.2 in. (.5 cm) long. Each silique contains 10–20 tiny black, cylindrical, ridged seeds, arranged in two rows. By June, most plants are dead, but the erect flower stalks with dry pale-brown seedpods remain through the summer, sometimes still holding seeds. Related or Similar Species. Several white-flowered native herbs, such as toothworts, sweet cicely, and early saxifrage, grow alongside garlic mustard. First-year garlic mustard plants may be confused with other rosette species, especially violets, white avens, and toothwort species in the Midwest and Northeast, and with fringecup and piggyback plant in the West. Although the effect dissipates toward autumn, garlic mustard can be distinguished by the garlic odor of its foliage. Plants have a slender white taproot with a distinctive crook shape close to the soil surface. Introduction History. Because garlic mustard can be used as a potherb or in salad, especially the rosette leaves in winter and early spring, it was probably introduced multiple times by settlers for food or medicine. It was first recorded in 1868 in Long Island, New York. By 1991, it had spread to 28 midwestern and northeastern states. It is considered a gourmet ingredient, and seeds can be ordered off the Internet. Habitat. Garlic mustard grows in a wide range of habitats, most often in deciduous forest communities with partial shade. It is found in both full sun and shade, upland forests, riparian forests on floodplains, roadsides, trails, forest edges, oak savannas, and urban areas. It is less frequent in woodlots surrounded by cropland. Although rarely found under conifers in the midwestern states, it invades those habitats in Ontario, Canada. Its habitat varies with geography. Garlic mustard is river-associated in the Northeast and along railroad right-ofways in the Midwest. It grows in riparian habitats and on waste ground on the Great Plains and along hiking trails in the eastern Rocky Mountains. Disturbed areas are most

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vulnerable to rapid invasion and dominance, but garlic mustard can also spread into healthy communities. It grows best in rich, moist soil, preferably calcareous, and does not tolerate high acidity. It can grow on sand, loam, clay, limestone, and sandstone, but is rare on peat or mucky soils. Flooding during the growing season may limit its extent. Reproduction and Dispersal. Although damaged plants may sprout new flowering stems from the root crown, garlic mustard reproduces exclusively by seed. Plants develop rapidly in their second spring, flowering, setting seed, and dying by late June. Flowers may be pollinated by bees and flies, but are also self-fertile, enabling one plant to populate an entire site. Each plant can produce over 500 seeds, allowing an extensive seed bank to accumulate in the soil. The seed pods burst when ripe, expelling seeds several feet from the parent plant, but humans and wildlife are responsible for long-distance dispersal. Rodents and birds also contribute to seed dispersal. Because seeds are easily transported by water, floodplains are vulnerable to invasion. Abundant seeds enable garlic mustard to rapidly invade sites after a disturbance. While browsing other plants, white-tailed deer trample the soil, inadvertently providing more disturbed area for garlic mustard. Seeds remain viable for five or more years but require 8–22 months of dormancy before germinating. Seeds germinate in early spring, which may be late February to mid-May, depending on geography. While native plants require light to germinate, garlic mustard has an advantage because it is able to germinate in both sun and shade. Although initial seedling density can be 500 or more per sq. ft. (5,000 per m2), only 2–4 percent survive to flower the following spring. Impacts. Because it grows in early spring and late fall when native plants are dormant, garlic mustard is one of the few plants able to invade the understory of forests in the United States. It dominates the herbaceous layer in woodlands, eliminating native plants and animals. Garlic mustard outcompetes native wildflowers, such as spring beauty, wild ginger, bloodroot, Dutchman’s breeches, hepatica, toothworts, and trillium, which also complete their life cycles in the spring. When these wildflowers are displaced, so is the wildlife that depend on them for pollen, nectar, foliage, fruits and seeds. Garlic mustard threatens the existence of native garden white butterflies. It appears to be toxic to the butterfly eggs because they fail to hatch when laid on that plant. The rare West Virginia white butterfly is dependent on two species of toothwort, crinkleroot, which is also called twoleaf toothwort, and cutleaf toothwort, as hosts for their eggs, plants which are often displaced by garlic mustard. Management. Eradication or control of garlic mustard is difficult due to the enormous numbers of seeds produced and their long-term viability. The best control is prevention and early detection. The goal should be to exhaust the seed supply, and sites should be monitored for seedlings for at least five years. Any physical removal of plants should minimize soil disturbance and be done before seeds mature. Hand removal is effective for small infestations or especially when garlic mustard threatens the survival of native plants, but the entire root system must be removed to prevent resprouting. Plants in larger areas can be cut at ground level every year until the seed bank is exhausted. If plants are cut too high on the stem, flowers will grow from leaf axils. All plant fragments should be removed from the site, especially if flowers or seedpods are present. Fire can be used in fire-adapted communities, but the ground disturbance opens the surface to seeds and encourages germination. If fire is used, sites must be burned annually for 3–5 years to deplete the seed bank. Chemical control is appropriate for heavy infestations where few native plants remain. Glyphosate is best applied to dormant rosettes in late fall or early spring, any time the temperature is above 50ºF (10ºC), and when native plants are still dormant.

372 n FORBS Possibilities of biological control are still being investigated. Garlic mustard has no natural enemies in the United States, but at least 69 species of insects and 7 species of fungi are associated with the plant in Europe. Five weevils and one flea beetle are being studied. Two weevil species (Ceutorhynchus alliariae and C. roberti) are effective in reducing seed production. Adults eat the leaves, and the larvae develop inside the stems and leaf petioles. The larvae of a root-mining weevil (C. scrobicollis) first mine the petioles and rosette leaves but do most of their feeding on the root crowns. Although the larvae of a fourth weevil (Ceutorhynchus constrictus) eat developing seeds, they fail to provide control. A fifth weevil (Ceutorhynchus theonae), more recently discovered in Russia, also attacks seeds and may be more effective. Impact of the flea beetle (Phyllotreta ochripes) is not yet known. Adults eat the leaves, while larvae eat the roots, rosettes, and bolting plants.

Selected References Blossey, Bernd, Victoria A. Nuzzo, Hariet L. Hinz, and Esther Gerber. “Garlic Mustard.” In Biological Control of Invasive Plants in the Eastern United States, by R. Van Driesche et al. USDA Forest Service Publication FHTET-2002-04, Morgantown, WV, 2002. http://www.invasive.org/eastern/ biocontrol/29GarlicMustard.html. “Garlic Mustard—Alliaria petiolata.” Southeast Exotic Pest Plant Council (SEEPPC) Invasive Plant Manual. Invasive Plants of the Eastern United States, 2003. http://www.invasive.org/eastern/eppc/ garlicmustard.html. Nuzzo, Victoria. “Element Stewardship Abstract, Alliaria petiolata.” Global Invasive Species Team, Nature Conservancy, 2000; updated 2009. http://wiki.bugwood.org/Alliaria_petiolata. Rowe, Pamela, and Jil M. Swearingen. “Garlic Mustard.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2009. http://www .nps.gov/plants/ALIEN/fact/alpe1.htm.

n Giant Hogweed Also known as: Giant cow-parsnip, cartwheel-flower Scientific name: Heracleum mantegazzianum Synonyms: Heracleum caucasicum, H. giganteum, H. panaces, H. speciosum, H. tauricum Family: Carrot (Apiaceae) Native Range. Caucasus region of Southwest Asia. Distribution in the United States. New England, northern midwestern states, and Washington and Oregon. Description. Giant hogweed is an herbaceous perennial that often reaches 10–20 ft. (3– 6 m) tall at the flowering stage. The plant is a rosette of leaves during its first year of growth, and leaf clusters become larger as the plant becomes older. After accumulating enough energy, over 2–5 years, plants bolt and flower in midsummer. The stout stems, 2–4 in. (5– 10 cm) in diameter, are coarse and ridged, with prominent white hairs, especially at the nodes. The stems and leaf stalks, which are both hollow, have dark reddish-purple spots. Both the leaf stalks and stems have small pustules (blister-like spots), each with a single sturdy bristle, that contain toxic sap. Leaves are alternate on the stem and have various shapes and sizes at different life stages. Young leaves at the base of the plant in spring are ternately compound, meaning that divisions each have three leaflets. As the plant grows, those leaves become larger, as wide as 5 ft. (1.5 m), with deeply incised lobes. Some leaves have measured almost 10 ft. (3 m) wide. Higher on the stem, the leaves are smaller, and

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the lobes are even more deeply cut. The lower surface of the leaves is densely covered with short, stiff hairs. Young plants develop a taproot in their first year. Lateral roots also develop, and the extensive root system gives the large plant stability. Foliage dies to the ground in winter, and buds on the tuberous root stalk sprout new leaves each spring. Plants flower in June and July. The large inflorescence, as wide as 2.5 ft. (.75 m), is a broad flat-topped, compound umbel, with many small white or greenish-white flowers. The small dry fruit, flattened, winged, and oval in shape, are approximately 0.4 in. (1 cm) long. Each contains one seed. Seeds are marked with brown swollen resin canals. Plants are believed to be monocarpic and die after flowering, although the dead stems often remain standing. Related or Similar Species. Although several native species in the carrot family resemble giant hogweed, the size of the Although currently present in few states, giant hogweed may become plant makes it distinct. Com- more expansive due to its unique qualities as an ornamental. (Native mon, or cow, parsnip is a range adapted from USDA GRIN and selected references. Introduced smaller plant, usually less than range adapted from USDA PLANTS Database, Invasive Plant Atlas of the United States, and selected references.) 6 ft. (1.8 m) tall. The hollow, ridged stems are usually less than 2 in. (5 cm) in diameter at the base and lack reddish purple spots. The palmately compound leaves, very pubescent on the undersides, are deeply incised but only 1 ft. (0.3 m) wide. The white flower umbels are rounded on top and 6– 12 in. (15–30 cm) wide. Purplestem angelica grows 4–6 ft. (1.2–1.8 m) tall, with a smooth, hairless purple stem and doubly compound leaves that are not dissected. Its white flowered inflorescence is round, not flat-topped, and 8–12 in. (20–30 cm) wide. Wild parsnip is 2–5 ft. (0.6–1.5 m) tall, with a yellow-green ridged stem. Yellow flowers are in flat umbels, 4–6 in. (10–15 cm) wide, and the yellow-green compound leaves have 5–11 leaflets. The watery sap from wild parsnip may cause a photosensitive reaction. Two alien species in the carrot family, both widely naturalized, may also appear similar. Queen Anne’s lace is small, 1–3 ft. (0.3–1 m) tall, with thin hairy stems. Flowers grow in a flat umbel, 3–6 in. (7.5–15 cm) wide, and the 6 in. (15 cm) long leaves are finely dissected.

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A. Giant hogweed can grow 2–3 times the height of a person. (Terry English, USDA APHIS PPQ, Bugwood.org.) B. The inflorescence is a large umbel. (Terry English, USDA APHIS PPQ, Bugwood.org.) C. Large stalks are hollow. (Leslie J. Mehrhoff, Ecology and Evolutionary Biology, University of Connecticut, Bugwood.org.) D. Large leaves are deeply lobed. (Donna R. Ellis, University of Connecticut, Bugwood.org.) E. Dried fruit, each with one seed, have prominent resin canals. (USDA APHIS PPQ Archive, USDA APHIS PPQ, Bugwood.org.)

The smooth, purple stems of poison hemlock reach 4–7 ft. (1.2–2 m) tall. The flowers are half-round umbels, 2–8 in. (5–20 cm) in diameter, and the compound leaves have fine, linear leaflets. Common elderberry, in the honeysuckle family and native to the United States, is a shrub or tree 2–10 ft. (0.6–3 m) tall with a woody gray-brown stem. White inflorescences are flat, 4–6 in. (10–15 cm) wide, and compound leaves have 5–7 leaflets, each 2–6 in. (5–15 cm) long. Introduction History. Because of its unique size, giant hogweed was probably brought to the United States as an ornamental. In 1917, it was found growing in a garden in New York, and it was reported in Canada around 1950. The dried fruit is used as a spice, called golpar, in Iranian cooking, and seeds are occasionally sold in ethnic food stores. Habitat. Giant hogweed is most common on disturbed sites, such as vacant lots, uncultivated fields, and along roads and railroads, but may also invade intact communities such as grasslands. It thrives in rich, moist soils in riparian zones along rivers and streams, where water easily distributes seeds. It also occupies ravines and ditches. Giant hogweed grows best in sunny locations and can be overgrown by native species in shady sites. When planted as an ornamental, it may escape to vacant lots or open space between residential communities. Reproduction and Dispersal. Giant hogweed reproduces by seed. Although it takes several years before plants grow flower stalks, one plant can produce 27,000–50,000 seeds. Most seeds fall near the parent, and natural dispersal is primarily by wind and water. The fruit is able to float for three days and may be carried as far as 6 mi. (10 km) distant. Seeds are also dispersed by birds that eat the fruit. Human activity also aids in the spread of giant hogweed. Seeds may escape from gardens or be contaminants in topsoil deposited along right-of-ways. Dried inflorescences are frequently used in decorative flower arrangements. Because they require a period of cold weather, seeds will not germinate in the summer they are produced, and seeds are viable for more than seven years. Germination begins in early

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spring and continues all summer, but the plant requires moisture to become established. Although plants usually die after flowering, they may offset, producing new plants from their root crowns. Impacts. The plant’s clear watery sap contains glucoside phototoxins, which react with sunlight. Brushing against the bristles or against broken stems or leaves will deposit the toxic sap onto the skin. The result is severe dermatitis, making the plant a serious health hazard in urban and suburban areas. In the 1970s, several children in Great Britain were affected after using the hollow stems as toys. Direct contact with the sap increases the skin’s sensitivity to the ultraviolet radiation in sunlight, often leading to severe burns that may require months to heal. Symptoms appear 15–20 hours after contact with sap and exposure to sunlight. Affected skin may redden and swell, often developing blisters, which break open to infection and frequently cause scarring. Contact of the sap with the eyes can cause either temporary or permanent blindness. It is advised to avoid breathing smoke from fires that contain giant hogweed fuel. Even birds and other animals have been reported to have experienced skin injuries from contact with the plant. Due to its abundant seed production, giant hogweed colonizes rapidly. Its larger leaves create a dense canopy that suppresses native riparian species, negatively affecting associated wildlife. Because the large plants die back to the ground in winter, the resulting exposure of bare soil may increase soil erosion along stream banks and on steep slopes. Other soil changes include a potential increase in nutrients because of the large amount of decaying biomass each year. Economic impacts include not only money spent to control infestations, but also funds spent for medical care. Management. Because of varying leaf morphology, plants in the rosette stage may go unnoticed, enabling the plant to grow and spread. After establishment, infestations may require five years to eradicate. Control measures should be repeated and sites frequently monitored, with the goal of both depleting root reserves and eliminating the seed bank. Anyone working with or around giant hogweed should avoid direct contact with the plant by wearing protective clothing. Work done after sunset will minimize the possibility of sunburns. If contact occurs, the skin should be covered to reduce sunlight exposure and immediately washed with soap and cold water. Physical control is the most commonly used method. If nothing else can be done, removal of flowers will prevent seed development. Plants can be dug out or cut below ground level. Although difficult to do, taproots should also be removed because root buds will sprout. All seeds should be destroyed by burning or taken to a landfill. Mechanical brush cutters can be used on large populations, just after the peak of flowering but before seed sets. Resprouts can be cut a few weeks later. Plants that are cut after seeds mature, however, will not resprout. Although mowing stimulates the buds on the root stalk, repeated mowing may exhaust the plant’s nutrient reserves. Grazing by cattle and pigs, which suffer no ill effects from eating the foliage, may stress the plant and limit flowering. Trampling also damages plants. Effective chemical control of giant hogweed can be achieved by applications of glyphosate or triclopyr, which will be absorbed into the roots. The best time for application on first-year plants is before they reach 2 ft. (0.6 m) tall or in the fall, after the first frost. Other herbicides, including 2,4-D, TBA, MCPA, and dicamba, kill the aerial parts of the plant but not the roots. No biological control is known. Although the toxic sap may be a deterrent to most insects, the caterpillars of some butterflies do feed on it. Several insect species found on giant hogweed in Switzerland are being investigated.

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Selected References “Giant Hogweed.” Environment and Natural Resources Institute. Alaska Natural Heritage Program. University of Alaska, Anchorage, 2005. http://akweeds.uaa.alaska.edu/pdfs/potential_species/bios/ Species_bios_HERMAN.pdf. “Giant Hogweed—Heracleum mantegazzianum.” Agricultural Program, Cornell University Cooperative Extension, Wyoming County, NY, n.d. http://counties.cce.cornell.edu/wyoming/agriculture/ resources/ipd/giant_hogweed.htm. Marrison, David L., and David J. Goerig. “Giant Hogweed.” Horticulture and Crop Science, Ohio State University Extension Fact Sheet. Columbus, n.d. http://ohioline.osu.edu/anr-fact/hogweed.html. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Heracleum mantegazzianum.” ISSG Global Invasive Species Database, 2005. http:// www.issg.org/database/species/ecology.asp?si=418&fr=1&sts. Nice, Glenn, Bill Johnson, and Tom Bauman. “The Infamous Giant Hogweed.” Purdue Extension Weed Science. Purdue University, West Lafayette, IN, 2004. http://www.btny.purdue.edu/weedscience/ 2004/articles/gianthogweed04.pdf.

n Goutweed Also known as: Snow-on-the-mountain, bishop’s weed, bishop’s goutweed, ground elder Scientific name: Aegopodium podagraria Synonyms: None Family: Carrot (Apiaceae) Native Range. Most of Europe and northern Asia to eastern Siberia. Distribution in the United States. Eastern half of the United States, from Maine south to Georgia and west to Minnesota and Missouri. Also the Northwest coast, Washington and Oregon, east to Idaho and Montana. It is either absent or uncommon in the drier western states. Description. Goutweed is an herbaceous perennial commonly used as a groundcover. Although sometimes called a vine, it does not have a climbing or twining habit. It grows as a mat, but with leaves and flowers held upright. Leaves are basal, meaning that the leaf stalks are attached directly to the rhizomes in the soil. The hollow stems holding the leaves grow 1 ft. (0.3 m) tall. The compound leaves are triternate, in three groups of three leaflets. The lower leaflets may be fused together, reducing the number of leaflets in the compound leaf. Leaflets are oval with a pointed tip and toothed or lobed edges, with no pattern to the teeth or the lobes. Leaves are medium green or pale gray-green, with each leaflet 1–3 in. (3–8 cm) long. The variegated form has bluish-green leaves with a white, creamy edge. Patches may be mixed because the variegated form often reverts to green. Goutweed is deciduous. After yellowing in August, leaves drop off the stem following the first frost in autumn. The root system is shallow, but extensive, with both main and lateral roots. The rhizomes are long, white, and branching, forming roots at each node. Horizontal rhizomes may develop vertical shoots at the end of the growing season. Rhizomes can be as short as 2 in. (5 cm) or as long as 9.8 ft. (3 m), but only 0.08 in. (2 mm) in diameter. Flower stems, reaching 2–3 ft. (0.6–0.9 m) tall, appear from May through August, depending on geographic location. The leafy stalks support flat-topped, compound umbels of small, five-petaled flowers. Flower clusters are 2–4.5 in. (6–12 cm) in diameter. Leaves, however, are much more numerous than flower stalks, especially in deep shade, and the white flowers are almost camouflaged by the white leaf variegation. Tiny brown, elongate seeds, resembling carrot seeds, ripen in late summer.

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Related or Similar Species. Aegopodium podagraria ‘Variegatum’ is the variegated variety, with no difference in habitat or invasive characteristics except that it may be less aggressive than the green form. Introduction History. Brought to the United States by European immigrants as an ornamental, goutweed was well established by 1863. The plant’s name stems from the once-held belief that it could be used to cure gout. The leaves were used as a salad ingredient in parts of Russia. Goutweed was uncommon in New England in the early 1980s and is currently expanding its range, especially in Vermont and Massachusetts. The plant is still readily available in nurseries and is one of the most common deciduous groundcovers in northern U.S. climates. Habitat. Goutweed’s natural history in North America has not been well studied, but its habitat preferences can be extrapolated from its native range. Its habitat in Europe is primarily deciduous forests, Goutweed colonizes disturbed sites and deciduous forests, primarily in especially riparian sites, but it is the eastern states. (Native range adapted from USDA GRIN and selected also found in shrublands, wet- references. Introduced range adapted from USDA PLANTS Database, lands, and grasslands. Although Invasive Plant Atlas of the United States, and selected references.) most often found on disturbed sites in North America, such as logged forest areas, abandoned fields, and pastures, it can also invade closed-canopy forests. In Europe, goutweed grows under the canopy of several types of deciduous forest trees, including ash, oak, beech, maple, and elm. It also grows in mixed forests where spruce, aspen, and linden are common, and is found beneath willows, birch, and alder. These same genera dominate the northern forests of the United States, which are susceptible to invasion. Goutweed is tolerant of poor soils and a range of soil acidity. It grows best on moist, well-drained soils, but may also tolerate saturated soils on floodplains. Lack of sufficient soil moisture may be a limiting factor in its extent. Goutweed grows well in part sun to full shade. Leaves will scorch if the site is hot, sunny, and dry. In Europe, it grows where annual precipitation is 19.5–32.8 in. (495–832 mm), and at elevations up to 3,488 ft. (1,063 m). Reproduction and Dispersal. Although goutweed is capable of producing viable seed, it spreads primarily by vegetative means, growing new stems from rhizomes and root

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A. Flower stems may be held high above the foliage. (Richard Old, XID Services, Inc., Bugwood.org.) B. Leaflets are in sets of three. (Richard Old, XID Services, Inc., Bugwood.org.) C. Leaves of the variegated form have white edges. (Richard Old, XID Services, Inc., Bugwood.org.) D. Plants have an extensive rhizome system. (Leslie J. Mehrhoff, Ecology and Evolutionary Biology University of Connecticut, Bugwood.org.) E. Flower clusters are flat-topped umbels. (Leslie J. Mehrhoff, Ecology and Evolutionary Biology University of Connecticut, Bugwood.org.)

segments. Established plants can expand by rhizome extension into both sunny and shady areas, and a clump can increase its diameter by more than 2 ft. (0.6 m) a year. Patterns of invasion are often clumped due to growth by rhizomes. Goutweed invades new areas by intentional transplants and by improper disposal of yard waste containing rhizomes. The fragrant flowers are pollinated by many insects, including beetles, bees, and small flies. Seeds have no specific dispersal mechanism and simply fall from the plant. They require a cold period and germinate the following spring, but do not seem to remain in the soil as a seed bank. Seedlings need disturbed sites and bright light and may not survive shady locations. Plants, however, rarely produce seeds, and seedlings are rare. Impacts. Most deciduous forests in the eastern United States are vulnerable to invasion by goutweed. Because goutweed is widely planted as an ornamental, infestations usually come from abandoned or poorly kept gardens. Moist forests near old residential neighborhoods or farmsteads are especially susceptible. Goutweed is aggressive, dominating the herb layer in forests and displacing native plants, which reduces species diversity. By forming a dense groundcover, it inhibits the germination and subsequent establishment of native tree species. Direct effects on wildlife are not known, but deer seem to avoid grazing it. Management. Because goutweed is limited in its extent, it may be possible to eradicate it before it spreads into new territory. Any site where it has been eradicated or controlled should be closely monitored for a few years to ensure that regrowth from rhizomes can be eliminated as it develops. Once goutweed is controlled, the area should be reseeded with native plants or noninvasive ornamentals, depending on the site, to avoid other invasive species from taking advantage of the bare or disturbed site. Reseeding or plantings may also be important to prevent soil erosion on the bare site. If used as a garden plant, goutweed should be planted in a restricted area—for example, confined by concrete, such as a sidewalk or foundation, to prevent unwanted spread by rhizomes. Physical means of control will rarely kill the plant. Digging it up breaks apart the root system and invigorates the plant, causing resprouting. Hand-pulling may be adequate for small patches, but all the rhizomes and stolons must be removed. Plant debris should be left to dry, then bagged and disposed of because any piece of root will grow. Frequent mowing may keep goutweed from spreading along roadsides or into gardens and lawns. Covering

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plants with black plastic when leaves begin to emerge in spring will prevent the plant from photosynthesizing and deplete its nutrient supply. Plastic should be left on all summer. An alternative method is to mow the leaves before covering with plastic. The plants, therefore, have used some of their reserves in growth but have no way of obtaining more. Covering plants in mid- to late-summer is ineffective because the roots have already acquired nutrient reserves. Chemical control requires a systemic herbicide, such as glyphosate. Repeated applications may be necessary to deplete the nutrient reserves. Contact herbicides only kill the leaves, and the plant resprouts from its extensive rhizome system within two months. Only new leaves can be killed by contact herbicides. By late summer, the cuticle on the old leaves is too thick to allow the herbicide to penetrate. Mowing in late summer, however, will stimulate new growth, which can then be sprayed. No biological control is available, because goutweed has no significant diseases or pests.

Selected References “Aegopodium podagraria ‘Variegatum.’ ” Ohio State University, n.d. http://hcs.osu.edu/hcs/TMI/ Plantlist/ae_raria.html. Garske, Steve, and David Schimpf. “Goutweed.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2005. http://www.nps.gov/ plants/alien/fact/aepo1.htm. “Goutweed Aegopodium podagraria L.” Weed of the Week. U.S. Department of Agriculture, Forest Service, Invasive Plants, 2006. http://www.na.fs.fed.us/fhp/invasive_plants. Waggy, Melissa A. “Aegopodium podagraria.” In Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, 2010. http://www.fs.fed.us/database/feis/.

n Halogeton Also known as: Saltlover Scientific name: Halogeton glomeratus Synonyms: Anabasis glomerata Family: Goosefoot (Chenopodiaceae) Native Range. Deserts and grasslands of southern Asia, including Kazakhstan, Uzbekistan, Turkmenistan, Afghanistan, and Pakistan, and eastward into southern Russia, Mongolia, and western China. Distribution in the United States. The northern Great Plains, from Nebraska to the Dakotas, and all states west of the Rocky Mountains. Description. Halogeton is an annual herbaceous plant that is semi-succulent. Plants vary in size, usually 3–18 in. (7.5–45 cm) tall and equally as wide. Several stems emerge from the base of the plant, spreading outward before bending to grow vertically. These main stems have many secondary branches, which are often tinged with red or purple. Stems grow only a few inches tall where stands are dense, but they can be 2 ft. (0.6 m) tall where plants are widely spaced. The fleshy, succulent leaves are alternate and sessile on the stem. Leaves are cylindrical, smooth and short, 0.2–0.9 in. (0.4–2.2 cm) long. At the end of the blunt leaf tip is a conspicuous but delicate needlelike spine. The foliage is glabrous, but leaf axils have tufts of long, cotton-like interwoven hairs. Plants have a dull bluish green tone in spring and early summer, but change color later in the season. By late summer, stems may turn pink or

380 n FORBS reddish, or both stems and leaves may become pink, red, salmon, or yellow. Leaves are deciduous or dried by the time seeds mature. Plants slowly grow a taproot as deep as 20 in. (50 cm), and lateral roots radiate as far as 18 in. (45 cm) in all directions Beginning in June and continuing through September, dense clusters of small flowers form in most of the leaf axils. Halogeton has two types of flowers, which produce two different kinds of seeds. Neither flower type has petals. The majority of flowers, 0.08–0.12 in. (2–3 mm) in diameter, have five fan-shaped, membranous or transparent sepals, narrow at the base and wider at the top. The fan-shaped sepals are greenish yellow, sometimes tinged with red. Smaller flowers have brown, toothlike sepals that look like bracts. Seeds mature from July to October. Winged dark-brown or black seeds are produced in late summer. The black seeds are Halogeton is toxic to livestock on western rangeland. (Native range enclosed by the fan-shaped adapted from USDA GRIN and selected references. Introduced range sepals, in clusters dense enough adapted from USDA PLANTS Database, Invasive Plant Atlas of the to cover and hide the stem. United States, and selected references.) Wingless light tan or brown seeds mature in early summer. They are completely enclosed by the brown toothlike sepals. Plants that germinate and mature late in the season produce black seeds only. Related or Similar Species. Young plants may resemble Russian thistle, another invasive species in arid regions of the western United States (see Forbs, Prickly Russian Thistle), but Russian thistle leaves are linear. It also does not have white hairs in the leaf axils, and its seeds are cone-shaped. Burning bush, also known as summer cypress or kochia, is an annual bushy forb growing 1–7 ft. (0.3–2.1 m) tall. Its taproot and resistance to insects and disease make it desirable as a forage crop for livestock. Dark green when young, plants became red as they mature. Its pubescent leaves and lack of a stiff spine at the tip differentiate it from halogeton. Introduction History. Halogeton was introduced to northern Nevada in the early 1930s, most likely as a contaminant in crop seed. The first herbarium specimen was collected in Nevada in 1934.

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A. Plants are usually less than 1.5 ft. (0.5 m) tall. (Joseph M. DiTomaso, University of California–Davis, Bugwood.org.) B. Small succulent leaves end in a short spine. (Bonnie Million, BLM, Ely District, Bugwood.org.) C. What appear to be petals are membranous sepals. (Clinton Shock, Oregon State University, Bugwood.org.)

Habitat. Halogeton is called saltlover because it does best in alkaline and saline soils, pH of 8–9 with a salt content of at least 5,800 ppm. It grows in the semiarid and high-desert regions of the West that receive 5–13 in. (127–330 mm) of annual precipitation, approximately 60–70 percent of which falls as snow. It can be found on any soil texture, from clay to loamy sands, which may or may not have a hard pan of calcium carbonate. The plant commonly grows around dry lakebeds or alkaline flats, at 2,500–7,000 ft. (750–2,150 m) elevation. It primarily invades disturbed sites in saltgrass, salt desert shrub, big sagebrush, desert grasslands, and pinyon and juniper woodland ecosystems. It often grows in association with other alien weeds, such as cheatgrass, clasping pepperweed, and Russian thistle. It also grows with native shrubs, such as greasewood and shadscale saltbush, and with native grasses, such as wheatgrass, needlegrass, Indian ricegrass, squirreltail, and galleta grass. It is typically found in areas associated with livestock, such as stock trails, bedding or feeding areas, watering sites, and overgrazed land. Halogeton is also common in human-disturbed areas, such as roadsides, gravel pits, airstrips, railroad right-of-ways, and abandoned farms, mines, and townsites. Numbers of plants and severity of infestations depend on sporadic precipitation, which triggers germination. Reproduction and Dispersal. Halogeton reproduces only by seed and is a prolific producer. One inch of stem can produce 75 seeds (35 per cm), and one large plant can produce more than 100,000 seeds. An infestation may produce 200–400 lbs. of seed per acre (222– 449 kg per ha). Seeds have several means of dispersal. The winged black seeds are easily wind-dispersed. Plants also break at the base of the stem and become tumbleweeds, pieces of which can be transported long distances when caught on vehicles. Road equipment, such as graders, also distributes stems and seeds. Dust devils can carry dry stems and seeds as far as 2 mi. (3.2 km). Seeds are resistant to animal intestinal tracts and are often deposited in manure. Two types of seeds with different germination requirements ensure regeneration of the plant. The black seeds drop off the plant by early November, have no dormancy requirement, and germinate in the first growing season after maturing. The brown seeds stay on the dried plant until January or February and remain viable in the soil seed bank for 10 or more years. They require a three-month dormant period of cold temperatures, slightly above freezing, before germination. Both types of seeds contain a coiled embryo. Either type germinates quickly after a rainfall, from February through mid-August, with a peak in April.

382 n FORBS Impacts. Although halogeton is not a competitive plant, it infests millions of acres of disturbed or overgrazed land in the western states. Once established, it can prevent regrowth of desirable native plant species because it alters the chemistry of the soil. Halogeton plants take salt from deeper layers in the soil and deposit it on the soil surface when they die. Soils become more alkaline and less permeable to water, which causes more evaporation. The salts also inhibit microorganism activity. Halogeton was first recognized as toxic in 1942. As a halophyte, the plant manufactures large amounts of oxalic acids due to its excessive uptake of sodium ions. The large quantities of the oxalate in the leaves and stems are poisonous to livestock. Usually unpalatable because of its bitter taste, hungry or thirsty livestock will eat the plant if nothing else is available. It is especially toxic to sheep, and thousands of animals have died after ingesting the plant. Signs of poisoning, which may occur as little as two hours after eating 12–18 oz. (340–510 g) of the plant, include weakness, staggering, rapid and shallow breathing, drooling, muscle spasms, and eventually coma and death. No treatment is available. The amount of oxalates varies by season and part of the plant, but is more concentrated in actively growing plants. Sheep may become adapted to the oxalates if they are slowly given gradually increasing amounts. The oxalates cause calcium to be lost from the blood, and sheep are frequently fed calcium-enriched feed to counteract the loss. Management. The best management is prevention, through maintenance of vigorous stands of pasture and range grasses and adoption of good grazing practices. All soil disturbances should be held to a minimum, including road construction and off-road vehicle use. To prevent poisoning, livestock should be kept away from infestations, especially after precipitation occurs because the moisture will trigger germination from the seed bank. It is possible to eradicate small, isolated patches. Sites should be monitored once or twice a year so seedlings may be killed before they have a chance to produce seed. This should be done for at least 10 years to exhaust the seed bank. For extensive stands, the cause of soil disturbance must be eliminated or reduced and the site replanted with grasses, forbs, or shrubs that can compete with halogeton. Physical removal of small plants or seedlings can be accomplished by hand-pulling. If flowering has begun, plants must be removed from the site to ensure that no seed develops. Mowing close to the ground will reduce, but not eliminate, seed production because short branches missed by mowing will flower. Prescribed burns are a poor choice because halogeton is one of the first plants to regrow after a fire. Although the fire may destroy existing plants and the seed bank, new seeds will be recruited from elsewhere to the now-exposed site. Seeding or encouraging perennials that can compete with halogeton may decrease its dominance. Although most wheatgrass species do not grow well on salty soils, a hybrid, such as A. desertorum cv ‘Hycrest,’ is adapted to saline conditions and can eliminate halogeton. Chemical applications of glyphosate can be used for spot treatment of small patches before flowering occurs, and repeated throughout the summer as new seedlings emerge. Metsulfuron is a better choice for more extensive infestations in pastures and rangeland

A Russian Spy Plot?

D

uring the Cold War, it was speculated that Russian spy planes introduced halogeton as a biological weapon.

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because it does not harm grasses. In field tests, dicamba and picloram were much less effective. Spraying must be repeated for 6–10 years to exhaust the seed bank. Although potential insects have been identified in Central Asia, biological control is not yet available. A stem-boring moth (Coleophora parthenica) from Pakistan was introduced to the United States, but it failed to become established.

Selected References Dewey, Steve. “Halogeton glomeratus.” In Invasive Plants of California’s Wildland, edited by Carla C. Bossard, John M. Randall, and Marc C. Hoshovsky. Berkeley: University of California Press, 2000. California Invasive Plant Council, 2006–2010. http://www.cal-ipc.org/ip/management/ipcw/pages/ detailreport.cfm@usernumber=53&surveynumber=182.php. “Halogeton (Halogeton glomeratus).” Plant Pest and Health Prevention Services (PHHPS), California Department of Food and Agriculture, n.d. http://www.cdfa.ca.gov/phpps/ipc/weedinfo/ halogeton.htm. Pavek, Diane S. “Halogeton glomeratus.” In Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, 1992. http://www.fs.fed.us/database/feis/plants/forb/halglo/all.html.

n Ice Plant Also known as: Highway ice plant, pigface, sea fig, Hottentot fig Scientific name: Carpobrotus edulis Synonyms: Mesembryanthemum edule Family: Stone Plant (Aizoaceae)

n Crystalline Ice Plant Also known as: Common ice plant, ice plant Scientific name: Mesembryanthemum crystallinum Synonyms: Cryophytum crystallinum Family: Stone Plant (Aizoaceae) Native Range. Coastal areas of southwest Africa. Distribution in the United States. Ice plant grows in California, from Eureka south into Baja California, and in Florida. Crystalline ice plant is in California, Arizona, and Pennsylvania. Description. Ice plant: Ice plant is a large, creeping, mat-forming perennial herb, which is sometimes referred to as a shrub. Stems are 0.3–0.5 in. (8–13 mm) in diameter and as long as 6.5 ft. (2 m). Stems become woody after several years growth. The very succulent leaves are arranged opposite on the stem and are much longer, 1.6–4 in. (4–10 cm), than they are wide, 0.2–0.5 in. (5–12 mm). They are either straight or slightly curved, triangular in cross section, with one edge of the triangle finely serrated. Large water-filled cells in the leaves often give them a shiny appearance. Leaf color ranges from dull green to bright green, with red, orange, or purple margins. More sun exposure increases coloring in the leaves. Flowering occurs all year, but the bloom peak is in late spring or early summer. The large flowers, 2.5–6 in. (6.5–15 cm) in diameter, are terminal and solitary, rising from 0.4–0.8 in. (1–2 cm) long pedicels. Dozens of narrow linear petals, pink, yellow, or yellowish white and 1.2–1.6 in. (3–4 cm) long, radiate from a center filled with many yellowish stamens. Flowers become pinker as they age. The edible fruit is a fleshy sphere or oval, 1–1.2 in. (2.5–3 cm)

384 n FORBS long, initially green but ripening to purplish red. They do not split at maturity but remain on the plant for several months. Each fruit contains numerous tiny black seeds. Crystalline Ice Plant: Although crystalline ice plant has different morphological characteristics, it causes many similar problems as an invasive. It is found from San Francisco Bay south to Baja, including the Channel Islands and as far as 8 mi. (13 km) inland. A low-growing, annual or biennial herb, it spreads over the ground on trailing stems. The succulent stems and leaves are green to reddish. Stems branch frequently and are usually less than 3.3 ft. (1 m) long. Leaves, growing 0.8–8 in. (2–20 cm) long on short petioles, are oval- to spoonshaped, with wavy margins. Leaves, stems, and fruit are covered with crystal-like projections that resemble tiny water bubbles. The majority of flowers bloom from March through June, but because germination Both species of ice plant are considered invasive in coastal California. takes place all year, some flowers (Native range adapted from USDA GRIN and selected references. can be found all year as well. The Introduced range adapted from USDA PLANTS Database, Invasive Plant flowers are small, 0.3–0.4 in. (7– Atlas of the United States, and selected references.) 10 mm), and stalkless, with many narrow white petals radiating from the center. Petal color changes to pink as the flowers age. Flowers have numerous stamens. After the fruits ripen in June through August, the plants dry from the base upward and die. Dried fruits burst to release many seeds. Germination begins with the first fall rains and fog and continues all winter. Seedlings grow rapidly until spring, but stop vegetative growth during the hot, dry summer. All parts of the plants are edible. Related or Similar Species. The genus Carpobrotus contains about 30 species, most of which are called ice plant. The common name ice plant refers to many other plants as well, such as Delosperma cooperi and Lampranthus spp. Sea fig, also called Chilean iceplant although it is native to South Africa, is a close relative that is smaller and less aggressive. Its magenta flowers are 1.5–2.5 in. (3.8–6.4 cm) in diameter. The two species of Carpobrotus hybridize naturally along the California coast, resulting in pink hybrid flowers intermediate in size. Hybrid plants are invasive.

ICE PLANT AND CRYSTALLINE ICE PLANT n 385

A. Ice plant mats can cover large areas. (Richard Old, XID Services, Inc.) B. The large ice plant flowers have many narrow petals. (Joseph M. DiTomaso, University of California–Davis, Bugwood.org.) C. Flowers of crystalline ice plant are smaller, and the oval leaves have wavy margins. (Joseph M. DiTomaso, University of California–Davis, Bugwood.org.) D. The long, succulent ice plant leaves are triangular. (Richard Old, XID Services, Inc.) E. Crystalline ice plant leaves are covered with tiny bubble-like projections. (Joseph M. DiTomaso, University of California–Davis, Bugwood.org.)

Introduction History. Ice plant was intentionally introduced to California in the early 1900s and used to stabilize soil along railroad tracks. It was subsequently planted along highways for the same purpose until the 1970s. Thousands of acres were planted in California. It is still promoted and sold in nurseries as an attractive garden plant, particularly along the coast due to its tolerance of salt. Crystalline ice plant was probably brought to California in the 1500s, in sand used for ship ballast. The California Department of Transportation used it for erosion control and landscaping in the 1950s, but stopped in 1969 when it was realized that it failed to stabilize soil on steep slopes and died during a hard freeze. Habitat. Ice plant tolerates a range of environmental conditions, such as soil moisture and nutrient content. It grows predominantly in coastal habitats, including dune scrub, prairie, bluffs, salt marsh, and maritime chaparral. Because it is intolerant of frost, it does not extend far inland or above 500 ft. (150 m) elevation. The plant’s invasive ability varies with the type and health of native plant communities. Seeds are most easily established on disturbed sites. Rodent disturbances in coastal prairie, for example, open bare soil patches. In a healthy, undisturbed community, the native prairie grasses can outcompete ice plant seedlings. Crystalline ice plant grows mostly on saline coastal soils, such as beaches, sage scrub, grasslands, estuaries, salt marshes, and bluffs. It easily spreads onto bare soil and disturbed sites. Grazing of coastal grasslands and continued natural erosion of coastal bluffs provide disturbed ground that encourages its spread. Its intolerance of frost limits its distribution. Reproduction and Dispersal. Ice plant reproduces and spreads both sexually and vegetatively. Each plant produces an abundance of fruit, each containing hundreds of seeds. The fruit are eaten by several mammals, including deer, rabbits, and rodents, all of which are significant in dispersal of seeds, because scarification in a digestive tract aids germination. Long trailing stems branch frequently and grow shallow, fibrous roots at every node in contact with the soil. All stems and shoots grow roots, and continue to grow when separated from the parent plant. Vegetative growth is extensive.

386 n FORBS Rabbits and mice eat the fruit and disperse the seeds of crystalline ice plant. It does not reproduce vegetatively. Impacts. Ice plant is invasive in Mediterranean climates similar to its native range, especially in California and Australia, where it often forms monospecific stands. It lowers biodiversity by either directly competing with native plants, both seedlings and mature shrubs, or by altering environmental conditions. Ice plant makes soils more acidic, and buildup of organic matter in sandy soils or dunes allows other nonnative plants to also invade. It has the biggest impact on native plants in drought years, and is quicker than natives to invade burned clearings. Specific endangered or sensitive native plants threatened by ice plant include Wolf’s primrose, pink sand verbena, and beach layia. Because ice plant has no dormant season, stems can increase their length more than 3 ft. (1 m) each year, even though it is somewhat limited due to grazing by rabbits. Stems grow over one another and form impenetrable mats blanketing the ground up to 19.5 in. (50 cm) thick. Individual plants eventually coalesce to cover areas as large as 165 ft. (50 m) in diameter. Because ice plant stabilizes coastal sand dunes more quickly than native plants do, dune buildup is decreased. Areas inland from the dunes may be subject to more wave erosion because of fewer large, protective dunes. Crystalline ice plant outcompetes native species because it is better able to withdraw moisture from the soil. Salts that accumulate in plant tissues return to the soil at the death of the plant, which increases the salt content on the surface beyond the tolerance of many native grasses and forbs. Levels of soil nitrate are higher under crystalline ice plant, which inhibits the growth of native grass seedlings. Management. Hand-pulling is an effective physical way of controlling small plants or populations, but it is expensive and labor intensive. Larger areas may be more easily removed using tractors or other machinery. Because fragments of ice plant will grow roots and sprout, all root and stem pieces must be removed from the soil. Reseeding with native species or mulching the area may help to suppress growth of any remaining pieces. Prescribed burning is not useful because of the high water content in both types of ice plant. Control by grazing is limited because leaves are too salty and astringent and the stems too fibrous and woody to be palatable to livestock. Because herbicides have detrimental effects on nontarget plants, chemical control can damage native plants. Foliar spraying is best done in winter when native plants are dormant, but the evergreen ice plant is not. Although glyphosate will kill plants, sprouts may reoccur for several months. Chlorflurenol, used along roadsides, is also effective. No biological controls are available. Ice plant scale insects (Pulvinariella mesembryanthemi and P. delottoi) do some damage, but not enough to affect growth. Parasitism by a dodder (Cuscuta sp.) also fails to do enough harm. Although no specific research has been conducted on eradication of crystalline ice plant, some of the same methods may be applicable. Because crystalline ice plant is an annual, however, efforts should target reducing seed production.

Selected References Albert, Marc. “Carpobrotus edulis.” In Invasive Plants of California’s Wildlands, edited by Carla C. Bossard, John M. Randall, and Marc C. Hoshovsky. Berkeley: University of California Press, 2000. http://www.cal-ipc.org/ip/management/ipcw/online.php. Randall, John M. “Mesembryanthemum crystallinum.” In Invasive Plants of California’s Wildlands, edited by Carla C. Bossard, John M. Randall, and Marc C. Hoshovsky. Berkeley: University of California Press, 2000. http://www.cal-ipc.org/ip/management/ipcw/online.php.

JAPANESE KNOTWEED n 387 Whittemore, Frank. “Why Is the Ice Plant Bad?” Garden Guides, 1997. http://www.gardenguides.com /88524-ice-plant-bad.html.

n Japanese Knotweed Also known as: Japanese bamboo, crimson beauty, Mexican bamboo, Japanese fleece flower, reynoutria Scientific name: Fallopia japonica Synonyms: Polygonum cuspidatum, Pleuropterus cuspidatus, Pleuropterus zuccarinii, Polygonum zuccarinii, Reynoutria japonica Family: Buckwheat (Polygonaceae) Native Range. Eastern Asia, including China, Taiwan, Japan, and Korea. Distribution in the United States. Most of the lower 48 states and Alaska. Especially prominent in the eastern half of the country, from Wisconsin east to Maine, south to Louisiana and Georgia, and west to South Dakota and Oklahoma. Stands are scattered in midwestern and western states. Description. Japanese knotweed is an herbaceous perennial that appears woody because of its upright stems that grow 3–10 ft. (1–3 m) tall with little side branching. Although it superficially resembles bamboo because of its straight growth of cane-like hollow stems, it is not related and can be distinguished by its leaf shape. The round stems, which are 1 in. (2.5 cm) or more in diameter, are smooth and sturdy. Swollen nodes, where leaves are attached to the stem, occur every 3–5 in. (7.5– 12.5 cm). Characteristic of all members of the buckwheat family, the stems have a membraneous sheath encircling the nodes. In Japanese knotweed, the sheath is often reduced to a

Japanese knotweed, which was used for erosion control, is more prevalent in the eastern states. (Native range adapted from USDA GRIN and selected references. Introduced range adapted from USDA PLANTS Database, Invasive Plant Atlas of the United States, and selected references.)

388 n FORBS

A. Japanese knotweed can grow 10 ft. (3 m) tall. (Richard Old, XID Services, Inc., Bugwood.org.) B. Leaves have smooth margins and a pointed tip. (James H. Miller, USDA Forest Service, Bugwood.org.) C. The rhizome system is extensive. (Ohio State Weed Lab Archive, The Ohio State University, Bugwood.org.) D. Small flowers grow on panicles at the ends of stems. (James H. Miller, USDA Forest Service, Bugwood.org.) E. Papery, winged fruits contain small seeds. (Barbara Tokarska-Guzik, University of Silesia, Bugwood.org.) F. Swollen nodes line the smooth stems. (James H. Miller, USDA Forest Service, Bugwood.org.)

red ring around the stem, which sometimes makes the stem appear reddish brown. The broadly oval leaves vary in size, but are usually 6 in. (15 cm) long and 3–4 in. (7.5– 10 cm) wide, with smooth margins and a pointed tip. Leaves are alternate and grow on the upper parts of the stems. The extensive root system, with rhizomes as long as 65 ft. (20 m), enables Japanese knotweed to form thick colonies. Rhizomes extend as deep as 7 ft. (2 m) into the soil, where they tap a wide source of water and nutrients. Each root crown produces 30–50 shoots, and individual plants can be 8–15 ft. (2.4–4.5 m) in diameter. Large clumps consisting of several plants can cover several hundred square feet or several acres and can dominate an entire shoreline. Intolerant of freezing temperatures, above-ground parts of the plants quickly die after frost. The bare, brown stalks remain upright all winter. Rhizomes survive and resprout rapidly in spring, as early as April or as late as June, depending on geographic region. Young sprouts resemble red asparagus. Because of root reserves, plants grow fast, as much as 1 ft. (0.3 m) each week, and if they resprout early in spring, they can reach 10 ft. (3 m) by June. In late summer to early fall, August to September, greenish-white or cream-colored flowers appear in panicles, or branched sprays near the ends of the stems. Flowers are tiny, 0.1 in. (3 mm), but the panicles are 3–6 in. (8–15 cm) long. Although all flowers have vestigial parts of both sexes, male and female flowers grow on different plants. Male inflorescences are upright, while female inflorescences are drooping. Pollination is done by bees and other insects, and fruit appears only two weeks after flowering. The fruit are small (0.25–0.4 in.; 6–10 mm), papery, and winged, containing very small, shiny black seeds, 0.15 in. (4 mm) long. Related or Similar Species. Giant knotweed and Bohemian knotweed, which is a hybrid between giant knotweed and Japanese knotweed, look similar to Japanese knotweed except for tiny hairs on the undersides of the leaves. Giant knotweed grows to 15 ft. (4.5 m) tall, with heart-shaped leaves and greenish flowers. Hybrid seeds are fertile. Nomenclature of knotweeds is in dispute, but the invasive effects are the same regardless of name. Introduction History. Japanese knotweed was from brought from Japan to the United Kingdom in 1825 as an ornamental, and then introduced to the United States from Great

JAPANESE KNOTWEED n 389

Britain in the late 1800s. Used for erosion control and landscape screening because of its dense network of rhizomes, it became invasive in natural habitats after escaping cultivation in gardens. By 1894, it had naturalized near Philadelphia, Pennsylvania; Schenectady, New York; and Atlantic Highlands, New Jersey. In 1910, it was advertised in seed catalogs, but by 1938, information was published on how to eradicate it from gardens. Habitat. Japanese knotweed is tolerant of many conditions, including full shade, high temperatures, drought, and floods. Its growth rate depends on soil quality and nutrients, and the species is more common in regions with high rainfall. The species grows on a variety of soils, including silt, loam, and sand, under saline, alkaline, or acid conditions. It thrives along streams, rivers, and other low-lying areas, but also invades disturbed ground, such as old homesites, abandoned farmland, ditches, roadsides, railroad tracks, and utility line corridors. It needs damp soil to become established, but grows in dry sites as well. It grows best in sun, and poorly in shade. In its native range, Japanese knotweed is the dominant pioneer on volcanic slopes and disturbed sites. Reproduction and Dispersal. New plants arise from seed, broken stems, and rhizome nodes. Although seeds are the normal means of reproduction in its native Japan, they are rarely produced in the United States, because fertile males are rare and clones are usually all male or all female. Seeds do germinate, however, when produced. Stands expand predominantly by vegetative means. Any fragment of the roots, rhizomes, or stems, as small as 0.5 in. (1.25 cm), will grow into a new plant. Even internode pieces will sprout. Fragments are relocated by water, wind, mud, as contaminants in fill dirt, or as discarded cuttings from urban gardens. Optimal sprouting takes place from rhizomes just below the soil surface, but sprouts are capable of emerging from rhizomes buried as deep as 3.3 ft. (1 m). Impacts. Specific problem areas include hundreds of acres of wetlands in western Pennsylvania, creeks in suburban Philadelphia, and Rock Creek National Park in Washington, D.C. Because of its propensity to grow from rhizomes that can extend up to 65 ft. (20 m) away from the parent plant, Japanese knotweed forms dense, monoculture thickets that exclude native vegetation and reduce biodiversity. Rapid growth in spring, over 3 in. (8 cm) per day, enables plants to shade out native species. Growing best in full sunlight, it is less likely to invade undisturbed forest and shady areas. Japanese knotweed is especially a threat to riparian areas, where it destroys habitat for fish and other wildlife and limits recreational opportunities. Not only can it survive extensive flooding, but it rapidly colonizes bare ground left by floodwaters. It pulls nitrogen out of the soil but does not return it in leaf fall, thereby altering the soil and aquatic nutrient exchanges. In the Pacific Northwest, Japanese knotweed threatens salmon due to loss of insects and shady areas because it outcompetes native plants. By providing shade and habitat for animals, native trees are an important part of the natural riparian environment. Native plants also stabilize the ground against erosion. Woody debris from native trees disrupts stream flow, resulting in the creation of pools of water for salmon. Japanese knotweed causes monetary loss because vigorous rhizome growth can break foundations and road beds. Management. It is probably not possible to eliminate Japanese knotweed everywhere. Management should be selective, as funds and personnel permit. Treated sites should be monitored frequently for regrowth. At minimum, areas 20 ft. (6 m) away from the original plants should be examined for sprouts, which can then be pulled before they become established. The origin of stands along the Hoh River in Washington State was traced upstream to a single ornamental planting from which pieces escaped cultivation. Therefore, any

390 n FORBS management along waterways must begin upstream, because broken pieces carried downstream will grow into new colonies. Complete physical removal may only be possible with small plants or small infestations. It is imperative that all parts of even a small plant be dug up and properly disposed of. Removing even a small patch of Japanese knotweed may take as long as three years. Digging plants is not practical, because the roots extend very deep and pieces break off. Repeated cutting or mowing stands, before regrowth reaches 6 in. (15 cm), at least three times a year for 2–3 years, will deplete root supplies and weaken the stand. Careless mowing, however, may actually increase the size of the stand, because pieces will grow, and one plant can quickly give rise to hundreds. Burning does not kill the plant, and the only benefit is that it opens access to dense stands for other means of control. Covering cut or mowed stands with black plastic will prevent plants from conducting photosynthesis, thereby depriving them of nutrients. Covering should remain in place for at least one year and be frequently checked for sprouts, both around the edges and through the material. Japanese knotweed has been observed growing through 2 in. (5 cm) of asphalt and can more easily penetrate even thick plastic. Grazing of young shoots by sheep, goats, cattle, and horses will not kill plants but serves the same purpose as mowing, to weaken the plant. Chemical control is possible with repeated applications and is more effective combined with cutting or mowing. Glyphosate or triclopyr may be applied to cut stumps within one half-hour after cutting, before the wound begins to heal, or may be directly injected into each stem. Because they are labor intensive, neither method is feasible for a large stand. Picloram is a selective herbicide but cannot be used near water. Applications of herbicide can be used in cold weather as long as the ground is not frozen. Systemics work best in early fall, when plants are actively moving nutrients into the roots. Foliar applications are effective on new growth or anytime the plant is in full leaf, but is best done before flowering. Using selections from a list of potential insects and pathogens from Japan, initial research on biological control of Japanese knotweed has been conducted in the United Kingdom, where the plant is also a serious invasive. Two insects, a leaf-chewing chrysomelid beetle (Gallerucida bifasciata) and a sap-sucking psyllid (Aphalara itadori), were imported into U.S. quarantine in 2007 for testing.

Beneficial Uses of Japanese Knotweed

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idely planted as an ornamental, Japanese knotweed may have other beneficial uses. Dried roots of the plant are steeped for tea in Asia, and the plant shows promise for medicinal use. It is a major source of resveratrol, the same substance that is in red wine, which is often sold as a nutritional supplement. Experiments with mice show that extracts from the plant may be anti-inflammatory, helping to prevent ulcers or to promote healing of burns. Compounds from the roots also seem to be beneficial in several ways. They inhibit growth of certain bacteria, may protect against cancer, and prevent formation of blood clots. Roots, with their concentrations of emodin, also sold as a nutritional supplement, are also used in Asia as a natural laxative.

KAHILI GINGER n 391

Selected References “Integrated Pest Management Profile, Japanese Knotweed.” Department of Ecology, State of Washington, 2007. http://www.ecy.wa.gov/programs/wq/plants/weeds/aqua015.html Mehrhoff, L. J., J. A. Silander Jr., S. A. Leicht, E. S. Mosher, and N. M. Tabak. “Japanese Knotweed.” Invasive Plant Atlas of New England (IPANE), University of Connecticut, 2003. http:// www.ipane.org. Nice, Glenn. “Japanese Knotweed, (Polygonum cuspidatum).” Extension Weed Science, Purdue University, 2007. http://www.btny.purdue.edu/weedscience/. Remaley, Tom. “Japanese Knotweed.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2009. http://www.nps.gov/plants/ALIEN/ fact/faja1.htm. Seiger, Leslie. “Element Stewardship Abstract, Polygonum cuspidatum.” Global Invasive Species Team, Nature Conservancy, 1991. http://wiki.bugwood.org/Polygonum_cuspidatum.

n Kahili Ginger Also known as: Awapuhi kahili, kahili, kahila garland lily, wild ginger Scientific name: Hedychium gardnerianum Synonyms: None Family: Ginger (Zingiberaceae) Native Range. Lower slopes, up to 4,100 ft. (1,250 m), of the Himalayas in Nepal and eastern India. Distribution in the United States. Hawai’i. Description. Kahili ginger is a non-woody perennial herb with thick, branching rhizomes. From May through July every year, buds on the rhizomes produce many new leafy shoots, which can be as tall as 5–6.5 ft. (1.5–2 m). The large oblong to lance-shaped leaves, 8–20 in. (20–50 cm) long and 4–6 in. (10–15 cm) wide, are shiny and alternate. The upper surface is glabrous, while the lower surface is sparsely pubescent. Tips are pointed, and leaves have no petioles. The ligules, where the leaf attaches to the stem, are membraneous, 0.8–1.6 in. (2–4 cm) long, and pubescent, but leaf sheaths are glabrous. The fleshy rhizomes, which are segmented into units 4 in. (10 cm) long and 1.5 in. (4 cm) in diameter, grow in an intertwined, solid mat that can be 3.3 ft. (1 m) thick in the soil. A distant relative of the ginger used in cooking, the rhizome interiors are pale, with a faint ginger smell and taste. Plants in Hawai’i flower in July and August. The erect inflorescence is a large spike, 10– 18 in. (25–45 cm) long, and cylinder shaped, with many lemon yellow zygomorphic flowers. The corolla is a slender tube, 3–3.5 in. (8–9 cm) long. Yellow structures that resemble petals, but are sterile stamens called staminodes, are 1.6–2 in. (4–5 cm) long. One long stamen, usually red but sometimes yellow, conspicuously extends beyond the yellow corolla. Flowers are very fragrant. After the flowers drop off, the fruiting spike remains upright with fleshy orange fruits, each 0.6–0.8 in. (1.5–2 cm) long. When mature, usually October through December, the seed capsules open on the stalk to expose small, shiny red, fleshy seeds, which become gray as they age. Related or Similar Species. Hedychium species readily hybridize, confusing the taxonomy of yellow ginger and white ginger. Yellow ginger, also known as cream lily, is native to eastern India and Nepal at elevations of 1,650–2,600 ft. (500–800 m). A significant pest in Hawai’i, it grows in forests, at forest edges, and along riverbanks. Stems grow 3.3–10 ft. (1–3 m) tall. The plant’s elliptical to lance-shaped leaves, 8–20 in. (20–50 cm) long and

392 n FORBS 1.5–4 in. (4–10 cm) wide, are more narrow than those of kahili ginger and more vertically oriented, pointing up. Leaf tips are pointed, and leaf sheaths are slightly pubescent. The flower spike is smaller, 6– 8 in. (15–20 cm) long and 1.2– 2.4 in. (3–6 cm) wide, with creamy to pale-yellow fragrant flowers, sometimes reddish yellow at the base. Green bracts below the corolla are distinctly imbricate (overlapping). Yellow ginger reproduces both by seed and by rhizome buds. White ginger, also known as ginger-lily, is native to the tropical wet regions of southeastern China and southern Asia, from India east to Vietnam and south to Malaysia and Indonesia. Although it can be found in full sun, it prefers partial shade, humus-rich soils, and waterlogged, but not submerged, soils. Its stems reach 3.3–10 ft. (1–3 m) tall. Leaf blades are lance-shaped, 8–16 in. (20–40 cm) long and 1.8–3 in. (4.5–8 cm) wide, glabrous on top and thinly hairy Kahili ginger grows best in wet or mesic environments in Hawai’i. (Native beneath. Elliptical flower spikes, range adapted from USDA GRIN and selected references. Introduced 1.5–8 in. (10–20 cm) long and range adapted from USDA PLANTS Database, Invasive Plant Atlas of the 1.6–3 in. (4–8 cm) wide, have United States, and selected references.) fragrant white flowers, sometimes tinged with yellow at the base. Seeds are bright red. Precise correlation of seed production and elevation is not known, but seeds do not develop at Kalopa State Recreation Area, on the Big Island, at 2,000 ft. (600 m). In Hawai’i Volcanoes National Park, seeds are produced only below an elevation of 4,000 ft. (1,200 m). Because it produces fewer seeds, white ginger spreads primarily by rhizomes. Introduction History. Kahili ginger was introduced to every island in the Hawaiian chain as an ornamental by Chinese immigrants in the early 1900s. It has since escaped from cultivation. When first recorded in Hawai’i Volcanoes National Park, it was kept in check by feral pigs (see Volume 1, Vertebrates, Mammals, Feral pig). Since the pigs were fenced out of the park in the 1970s, the ginger now grows uncontrolled. Habitat. Kahili ginger thrives in both bright light and in dense shade. Although it prefers fertile soils and mesic to wet conditions, including areas with poor drainage, it can also grow on soils with low fertility, in very little soil, or in thick humus. It even grows successfully in

KAHILI GINGER n 393

A. New shoots grow from the dense mat of rhizomes. B. Both the inflorescences and leaves are large. C. Flowers are zygomorphic. D. The fruit, fleshy at first, dries on the stalk. (Forest and Kim Starr, U.S. Geological Survey, Bugwood.org.)

moss-covered forks of trees or on branches. Plants can be found in agricultural land, coastland, natural rainforests, montane forests, forest plantations, grasslands, riparian sites, wetlands, and shrublands. Kahili ginger dominates early succession in sites destroyed by fire. Both yellow ginger and white ginger are usually found at the forest edges, not in dense shade beneath the canopy. Reproduction and Dispersal. Reproduction is both sexual and vegetative, Kahili ginger spreads by seeds, rhizomes, intentional plantings, and careless disposal of garden trimmings. All rhizome pieces sprout stems, and also grow outward to expand the size of the clump. Each clump has several flower heads, and each flower head produces 20–600 seeds. Fewer seeds are produced in low light under forest canopies. Dense infestations in Hawai’i may have 200 seeds per sq. ft. (2,000 per m2). Dispersal over longer distances to new areas occurs when birds eat the fruit and expel the seeds. The two birds primarily responsible for dispersal are both introduced species, the Japanese White-eye and the Red-billed Leiothrix. Although passage through the digestive tract may enhance germination of seeds, most seeds are viable for only one year. Impacts. Because kahili ginger grows quickly, lives at least 70 years, and sprouts from rhizomes when stems are removed, it has the potential to invade all wet habitats in Hawai’i below 5,500 ft. (1,700 m) elevation. Kahili ginger does not need disturbance and can invade healthy, closed-canopy forests, where plants thrive because the species is shade-tolerant. It outcompetes native plants for light, space, nutrients, and moisture, displacing the understory of native mosses, ferns, and shrubs. Because seedlings of native plants cannot grow through the thick rhizome mat, kahili ginger prevents forest regeneration, with the result that the multilayered forest is replaced by dense, monospecific thickets. Infestations of kahili ginger change the habitat for wildlife, especially for birds. Results from a study conducted in Hawai’i Volcanoes National Park indicated that populations of Japanese White-eye (see Volume 1, Vertebrates, Birds, Japanese White-Eye), a nonnative bird, increased in ginger-dominated forests. Although the rhizome system is extensive, the shallow roots beneath the rhizome mat do not grip the soil well. Due to the weight of the rhizomes mass, the entire plant often falls as a unit from steep, wet slopes. Such erosion downgrades water quality and causes siltation. The rhizome mat can block stream flow, altering hydrology. The density of the rhizome mat prevents water from infiltrating and percolating to the water table, reducing the forests’ usefulness as watersheds.

394 n FORBS Management. Eradication of kahili ginger is very difficult, usually requiring a combination of physical removal and herbicide application. Physical removal includes digging out small stands or small plants and cutting off top growth of larger plants. All rhizomes must be removed when plants are dug out. Because fruit consumed by birds is a major means of dispersal, inflorescences should be pulled off before seeds mature. If seeds are mature, care must be taken to properly dispose of the flower heads. Because the cut stems and leaves do not sprout, they can be composted. Fire is inefficient because neither stalks nor roots burn well. Additionally, most sites are too ecologically sensitive to attempt control by burning. Kahili ginger is not poisonous and is palatable to livestock. Chemical control is necessary for large plants. Herbicides applied directly to exposed rhizomes after foliage is removed is the most effective means of control, although it may take 12–15 months for rhizomes to die. Treated rhizomes will not sprout and can be left in place to decay. Metsulfuron-methyl is the most effective herbicide sprayed on foliage, but it will also damage nontarget native plants. The most efficient method is to chop down the stalks and spray the regrowth when it reaches 20–24 in. (50–60 cm) tall. Glyphosate is also an effective foliar spray. Kahili ginger may also be controlled by imazapyr, amitrol, and triclopyr ester. Glyphosate is effective on rhizomes of white ginger after the shoots have been removed. White ginger is also sensitive to foliar application of picloram and to metsulfuron, and to some extent to triclopyr. Yellow ginger is extremely sensitive to metsulfuron applied to cut rhizomes. A bacterium (Ralstonia solanacearum), which causes bacterial wilt, shows good potential as a biological control agent for kahili ginger. This bacterium is host-specific and does not harm either white ginger or yellow ginger. Experiments have shown that spraying with a bacteria solution, which is easily produced, decreased fruit, stunted growth, wilted leaves, and promoted rhizome decay. The bacterium is now established in soils at Hawai’i Volcanoes National Park and is expanding its range by means of soil water and insect movements.

Selected References Buddenhagen, Chris. “Ecology of Hedychium gardnerianum.” ISSG Global Invasive Species Database, 2006. http://www.issg.org/database/species/ecology.asp?si=57&fr=1&sts=&ang=EN&ver=print &prtflag=false. Csurhes, Steve, and Martin Hannan-Jones. Pest Plant Risk Assessment, Kahili Ginger, White Ginger, yellow Ginger. Department of Primary Industries and Fisheries, Queensland Government, Brisbane, Australia, 2008. http://dpi.qld.gov.au/documents/Biosecurity_EnvironmentalPests/IPA-Kahili -Ginger-Risk-Assessment.pdf. “Wild Ginger.” Pest Facts 4. Northland Regional Council, New Zealand, n.d. http://nrc.govt.nz/upload/ 2398/Plant%20Pests%2004%20-%20Wild%20Ginger.pdf.

“Kahili” Sounds Like It’s Native to Hawai’i

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ahili ginger got its Hawaiian name because the flowering stalks were thought to resemble the feathered staffs used by Hawaiian royalty to show their status and lineage.

LEAFY SPURGE n 395

n Leafy Spurge Also known as: Wolf’s milk, Fuitour’s-grass Scientific name: Euphorbia esula Synonyms: Euphorbia virgata, Tithymalus esula, Galarhoeus esula, and others Family: Spurge (Euphorbiaceae) Native Range. Europe and Asia, including western Russia, the Caucasus region, Southwest Asia, Mongolia, China, and Korea. Distribution in the United States. Most of the United States except the southern states. From the West Coast east to New Mexico, through the Great Plains States, the Midwest, and into the Mid-Atlantic states and New England. Description. Leafy spurge is an erect branching perennial herb reaching 2–3.5 ft. (0.6– 1 m) tall. Plants become woody at the base when mature. The smooth, or sometimes hairy, stems often occur in clusters arising from one root. All parts of the plant exude a white latex, or white milky sap, increasingly so as the plant ages. Leaves are stalkless and variable in both shape and size. They may be linear, lance-shaped, or oval, 1–4 in. (2.5–10 cm) long and 0.25 in. (6 mm) wide. Tips are either pointed or rounded, and leaf margins are smooth or slightly wavy. Leaves are alternate on the stem, but so closely spaced that they may seem to be opposite or even whorled. Leaves on seedlings are similar to those on mature plants, but smaller, and leaf pairs are rolled or folded together. The bluish-green color gives the plant a slightly frosted appearance. Stems die back at the onset of the cold season, turning yellow or red before leaves drop. Plants need approximately 42 days of chilling temA common invader of grassland or rangeland, leafy spurge may be peratures to break dormancy accidentally dispersed by farm machinery. (Native range approximated the following spring. from USDA GRIN and selected references. Introduced range adapted Leafy spurge has a complex from USDA PLANTS Database, Invasive Plant Atlas of the United States, root network that is tough and and selected references.)

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A. The many branches make the plant appear shrubby. (Steve Dewey, Utah State University, Bugwood.org.) B. Tiny floral parts are surrounded by cup-shaped bracts. (Norman E. Rees, USDA Agricultural Research Service, Bugwood.org.) C. Leaves are often linear. (Steve Dewey, Utah State University, Bugwood.org.) D. Flower clusters grow at the end of stems. (George Markham, USDA Forest Service, Bugwood.org.) E. Leafy spurge (right) is larger and more leafy than the ornamental cypress spurge. (Leslie J. Mehrhoff, Ecology and Evolutionary Biology, University of Connecticut, Bugwood.org.) F. The complex root system is tough. (Steve Dewey, Utah State University, Bugwood.org.)

woody. Long horizontal roots and short feeder roots grow within 12 in. (30 cm) of the soil surface. Several vertical roots extend as far as 10–20 ft. (3–6 m) into the soil, occasionally reaching 30 ft. (9 m) deep. Long, old roots become corky and drought tolerant. The extensive root system stores an abundance of nutrient reserves, and the roots and root crowns have numerous regenerative buds. First-year shoots, which are more abundant at the edges of clone infestations, do not yet have a woody crown. What appear to be yellow-green flowers, the showy part, are bracts at the base of the flowers. The tiny flowers are reduced to the basics. Each female flower consists of one pistil, and each male flower consists of one stamen. What looks like a flower is actually one female surrounded by 11–21 males, all inside a cuplike bract. The bract clusters begin to develop in late May and early June, with the flowers following in mid-June. Plants may flower again in the fall. Flowers have abundant pollen and nectar and are pollinated by at least 60 insects in the United States. Fruits are smooth, round, three-celled capsules 0.01 in. (3 mm) in diameter. The tiny seeds, one to a cell, are oval, smooth and gray-brown to purple with yellow flecks. Related or Similar Species. Leafy spurge is variable in its native range, and many regional biotypes exist in the United States, confusing the taxonomy of these spurges. Leafy spurge may be a hybrid or a series of hybrids. Toothed spurge, also known as serrate spurge, and eggleaf spurge are very similar to leafy spurge. Madwoman’s milk, also called sun spurge, is an annual. Caper spurge, or gopher plant, may be either an annual or a biennial. The more recently introduced Geraldton carnation weed is a perennial, as is the ornamental cypress spurge. Several of these spurge species are invasive or potentially invasive. Introduction History. First recorded in Massachusetts in 1827, leafy spurge is believed to have arrived in the United States as a contaminant in seed in the early 1800s. Introduction

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from Russia, in ship ballast and seed contamination in grain, probably occurred multiple times. By the early 1900s, the plant had reached as far west as North Dakota. It is currently spread with commercial seed, forage, or hay, and by fragments attached to farm or road equipment. Habitat. Leafy spurge has wide environmental tolerances. It is found in subtropical to subarctic climates, and xeric to mesic sites. In its native range, leafy spurge occupies grasslands, hedges, and ruderal habitats. In the United States, it is most common in grassland and rangeland. It easily invades disturbed prairies, savannas, pastures, abandoned fields, and roadsides, but it also is found in undisturbed prairies and woodlands. Although it grows in moist to dry habitats, leafy spurge is most aggressive in dry areas, where it encounters less native competition. It is present on all soil types but grows best in coarse-textured soil. Plants tolerate flooding for as long as four months, and occupy stream and ditch banks. Although it can grow in shade, leafy spurge prefers sunlight. Fewer flowers and shoots are produced under shady conditions. Reproduction and Dispersal. Because leafy spurge reproduces both sexually and asexually, it grows and spreads quickly. Stands usually start by seed, then expand vegetatively. Reproduction in sandy soils is predominantly vegetative due to a small soil seed bank, approximately 20 seeds per sq. ft. (200 per m2). In clay soils, with approximately 200 seeds per sq. ft. (2,000 per m2), 60 percent of sprouts emerge from seeds. Times of emergence, flowering, seed set, and germination vary with geographic location. Seeds mature about 30 days after flowering occurs, usually in late July. Each flower stem can produce 250 seeds. The seed capsules open explosively, ejecting the seeds as far as 15 ft. (4.5 m) away from the parent plant. Long-distance dispersal is aided by water and wildlife. Seeds that survive the digestive tract of sheep and goats are spread through their manure. Because no dormancy or cold period is required, seeds are able to germinate as soon as they mature. Seeds have a high germination rate, 99 percent in the first two years, and they remain viable in the soil for 7–9 years. Optimal temperatures for germination are 68–85ºF (20–30ºC), preferably with alternating freezing and thawing combined with periods of darkness. With sufficient moisture, seeds germinate throughout the growing season. Although many seedlings appear to die, they resprout from root buds that developed soon after germination. Stems from seedlings and root buds usually do not flower the first year. Plants also reproduce from the roots and root crowns. Root buds are primarily within 12 in. (30 cm) of the soil surface, but root pieces 9 ft. (2.8 m) deep can grow new plants. Buds remain viable for 5–8 years. Any root fragment, even as small as 0.5 in. (1.25 cm), can grow into a new plant. Clones extend their cover vegetatively at the rate of several feet per year. Damage to aerial plant parts stimulates the root buds. Impacts. Leafy spurge is very aggressive and a major problem in drier western states. Over five million acres (2 million ha) in the United States and Canada are infested. It can completely take over large areas, forming dense patches that replace native grasses and forbs by shading the ground and tapping water and nutrients. Because it can germinate when temperatures are close to freezing, leafy spurge is one of the first plants to emerge in spring. Its thick litter layer smothers the ground, and the decomposing plant tissue exudes a toxin that prevents other plants from growing. Severe infestations reduce both biodiversity and carrying capacity of rangeland. Studies on the Great Plains indicate that numbers of species of native grassland birds decline where leafy spurge is dense. The sap causes skin irritation, blisters, or severe rashes in humans, and can seriously damage the eyes. Because of the white sap, which affects the digestive tract in a similar manner, it is unpalatable or even toxic to native herbivores, such as elk, deer, and antelope.

398 n FORBS Significant ingestion can be fatal to cattle, which will not eat leafy spurge unless nothing else is available or the plant is a contaminant in hay. Leafy spurge infestations are responsible for significant economic losses, and can reduce crop yields by 10–100 percent. A conservative estimate of monetary loss in 1979 due to cost of control and loss of productivity was $10.5 million. A 1990 study concluded that the direct financial impact in Montana, North Dakota, South Dakota, and Wyoming was $40.2 million, with a secondary impact of $89 million. Economic impact in the Dakotas, Montana, and Wyoming is estimated at $144 million a year in crop and animal losses and control expenses Management. The best control of leafy spurge is early detection and elimination. Once it has gained a foothold, its deep root system and multiple buds make it almost impossible to totally eradicate. The abundant reserves in the root system enable the plant to survive repeated removal of aerial parts. Sites should be monitored for regrowth for at least 10 years after supposed eradication. Physical means may control the growth and spread, but it is highly improbable that plants can be eradicated because most physical removal does not affect the roots except to stimulate bud growth. Very small stands may be removed by hand-pulling or digging, but every piece of root must be removed. Gloves provide protection from toxic sap. Physical removal, however, disturbs the soil and other plant species, exposing more areas that may become infested. Continuous grazing by sheep and goats can reduce the plant’s density by adversely affecting reserves and seed production, but root crown buds will continue to sprout for several years after grazing stops. Sheep and goats should also be quarantined after grazing leafy spurge to prevent the transport of seeds in their manure. Cultivation or disking of infested fields is inadvisable because it spreads root pieces. Fire is generally not successful because roots and root crowns will resprout, but it does remove litter and other dead plant material. It may also encourage native bunchgrasses to grow and compete with leafy spurge. Fire may provide good control if repeated for at least 5–10 years. Any chemical treatment must be repeated over several years in order for the reserves in the roots to be depleted. Timing is critical. Chemical applications work best when combined with grazing, but can be detrimental to beneficial insects, including biological control agents. Leafy spurge can purge unwanted chemicals, such as herbicides, from its surface root system. The rest of the root regenerates after the soil concentration of herbicide has dissipated. Systemics, such as glyphosate or 2,4-D, are best applied in June on the developing flowers and seeds, or in mid-September when plants are transporting nutrients into the roots. Picloram is the most effective herbicide and, in combination with 2,4-D, can provide 90–95 percent control after five years. Research shows that chemical treatment in the fall combined with a spring burn reduces seed production, which in turn reduces the infestation. Native grasses respond well when herbicide is selectively applied to leafy spurge. The potential for biological controls is good. Twelve insect species, natural enemies from Europe and China, have been released in the United States since 1965, but few have established populations. These insects may help to manage infestations, allowing native plants to effectively compete with leafy spurge. Larvae of the hawkmoth (Hyles euphorbiae) eat the leaves and flowers but have succumbed to predation by ants, carabids, and mammals. The larvae of three clearwing moths (Chamaesphecia spp.) feed on roots but also failed to establish. A longhorn beetle (Oberea erythrocephala) has become established in Montana. The adults eat stems and roots while larvae feed on the root crown and roots. Four species of flea beetles (Aphthona spp.) now have established populations and have been the most successful in defoliating plants. Adults feed on stems, leaves, and flowers, but more important, the

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Successful Eradication

R

esults of biological control, documented by before and after photos by Team Leafy Spurge, illustrate that insect pest introductions can be successful in as little as two years. After 40 years of herbicide use failed to limit dense leafy spurge infestations on his rangeland, a rancher in Montana introduced flea beetles and is now a firm supporter of biological control. Densities of leafy spurge in other sites have been reduced from almost 50 percent cover down to 12 percent, allowing native grasses to recover. Source: Team Leafy Spurge, n.d.

larvae eat the root hairs and roots, opening them to fungal infections. The short-tip gall midge (Spurgia esulae) causes galls to form, which prevents flowering.

Selected References Biesboer, David D. “Element Stewardship Abstract, Euphorbia esula.” Global Invasive Species Team, Nature Conservancy, 1996; modifed 2009. http://wiki.bugwood.org/Euphorbia_esula. “Euphorbia Genus.” Plant Pest and Health Prevention Services (PHHPS), California Department of Food and Agriculture, n.d. http://www.cdfa.ca.gov/phpps/ipc/weedinfo/euphorbia.htm. “Leafy Spurge, Euphorbia esula L.” 2005. Alaska Natural Heritage Program. Environment and Natural Resources Institute, University of Alaska, Anchorage, 2005. http://akweeds.uaa.alaska.edu/pdfs/ potential_species/bios/Species_bios_EUES.pdf. “Leafy Spurge, Euphorbia esula L.” Weed of the Week. U.S. Department of Agriculture, Forest Service, Invasive Plants, 2006. http://www.na.fs.fed.us/fhp/invasive_plants. Nowierski, R. M., and R. W. Pemberton. 2002. “Leafy Spurge.” In: Biological Control of Invasive Plants in the Eastern United States, by R.Van Driesche et al. U.S. Department of Agriculture, Forest Service Publication FHTET-2002-04, Morgantown, WV, 2002. http://www.invasive.org/eastern/biocontrol/ 14LeafySpurge.html. Team Leafy Spurge. “Leafy Spurge Biological Control Information and Photo Resource Gallery”, n.d. http://www.team.ars.usda.gov/v2/photos.html.

n Musk Thistle Also known as: Nodding thistle, plumeless thistle Scientific name: Carduus nutans Synonyms: C. nutans ssp. leiophyllus, C. nutans ssp. macrocephalus, C. nutans ssp. macrolepis, Carduus armenus, C. thoermeri, C. coloratus, C. schischkinii, and others Family: Sunflower (Asteraceae) Native Range. Western and central Europe, north to Scotland, east to Yugoslavia, and the Ukraine. Also the western part of Asia from the Caucasus east to western China. Distribution in the United States. Every state except Maine, Vermont, Florida, Alaska, and Hawai’i. Most problematic in the Northwest Coast, the Rocky Mountains, Great Plains, Upper Midwest, and central Atlantic states. Description. Musk thistle is an aggressive biennial herb. In their first year of growth, seedlings develop a large flat-lying basal rosette, up to 5 ft. (1.5 m) in diameter. The plant

400 n FORBS flowers in the second year, rarely in the first year, sending up a flower stalk 1.5–6 ft. (0.5–1.8 m) tall. Plants have considerable variation in leaf size, spine length, flower head diameter, hairiness, and shape of bracts. Leaves and stems are spiny. The coarsely lobed leaves are dark green, with a smooth waxy surface, prickly toothed margins, and a yellowish-white spine at the tip. Leaves in the basal rosette are lance-shaped and can be as large as 16 in. (40 cm) long and 6 in. (15 cm) wide. The stem leaves are alternate and smaller, 3–6 in. (7.5– 15 cm) long, with light-green midribs and a white margin. The base of each leaf extends down the full length of the stem to form a narrow, spiny winglike structure. Many small roots develop in the fall after seeds germinate. A long, fleshy taproot, which may be branched, develops in the spring. Corky and hollow near the soil surface, the taproot may extend to a depth of 16 in. Musk thistle grows in a variety of environments, but is absent from deserts, (40 cm) or more. Plants begin to bolt in shady forests, and coastal areas. (Native range adapted from USDA GRIN and selected references. Introduced range adapted from USDA PLANTS March, and flowers appear from Database, Invasive Plant Atlas of the United States, and selected references.) May through September. Flower stalks, one or more rising from the root crown, are multi-branched. Large, showy disc-shaped flower heads, 0.8–3 in. (2–7.5 cm), occur singly at the tips of stems. The base of the flower head resembles a pine cone, with many large, lance-shaped bracts, tipped with spines. The outer bracts are broad, as wide as 0.4 in. (1 cm), with long, flat spine tips. The soft, narrow inner bracts may be purplish and are only sparsely spiny. Hundreds of tiny red-purple tubular flowers, each 1.5–3.5 in. (4–9 cm) long, comprise the disc flower. The short, 0.8 in. (2 cm) pedicels bend at maturity, causing the flower heads to droop at a 90-degree angle to the stem. Seeds mature about one month after flowering occurs. Each plant produces thousands of smooth strawcolored seeds, 0.1–0.2 in. (3–5 mm), with cream-colored plumed bristles. Related or Similar Species. The taxonomy of musk thistle is not clear, because plants exhibit considerable variation in morphological characteristics. Carduus nutans may be one species with four subspecies or three separate species. The genus Carduus has several

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A. Flowering plants can be as tall as 6 ft. (1.8 m). (Norman E. Rees, USDA Agricultural Research Service, Bugwood.org.) B. Musk thistle flowers (right) are distinctly different from bull thistle flowers (left). (Steve Dewey, Utah State University, Bugwood.org.) C. Plants grow as a rosette in their first season. (Richard Old, XID Services, Inc., Bugwood.org.) D. Stems are covered with sharp prickles. (Steve Dewey, Utah State University, Bugwood.org.) E. Seedheads are filled with plumed bristles. (Steve Dewey, Utah State University, Bugwood.org.)

additional species similar to musk thistle, all of which are erect plants with prickly winged stems and leaves. Common names may be confusing because they are not always distinctive. Scientific names provide more clarity. No Carduus species are native to the United States. Plumeless thistle (Carduus acanthoides) is a winter annual or biennial herb growing as tall as 5 ft. (1.5 m). Its basal leaves are 4–8 in. (10–20 cm) long. This plant is distinguished by its erect flower heads less than 1 in. (2.5 cm) in diameter and narrow, lance-shaped hairy bracts. It is more abundant in the northern states. Musk thistle and C. acanthoides readily hybridize, resulting in plants with intermediate characteristics. Italian thistle (Carduus pycnocephalus), from the Mediterranean region, and slenderflowered thistle (Carduus tenuflorus), from central Europe, are primarily winter annuals reaching 6.5 ft. (2 m) tall. C. pycnocephalus has narrow cylindrical heads 0.6 in. (1.5 cm) across, in clusters of 2–5 at the ends of branches. Its leaves are covered with wooly hairs. Flowerheads of C. tenuflorus occur in clusters of 5–20. C. pycnocephalus and C. tenuflorus are currently found in only a few states but are expanding their ranges. Because C. tenuflorus is self-pollinating, these two species rarely hybridize. Other introduced thistle genera are also invasive. Cirsium species are differentiated from Carduus species by pappus hairs which are divided and feathery. Native to southwestern Asia, Canada thistle (Cirsium arvense; see Forbs, Canada Thistle) is a perennial with creeping roots that give rise to new plants. It has small unisexual flower heads, with male and female flowers on different plants. Its stems and flower heads are smooth rather than prickly. The upper leaf surfaces of bull thistle (Cirsium vulgare), a coarse biennial native to Europe and North Africa, are covered with stiff bristly hairs, making them rough to the touch. Although the leaves of Scotch thistle (Onopordum acanthium), a plant native to Scotland, are tipped in spines, the plant is covered with silvery white cottony wool rather than with bristles.

402 n FORBS Starthistles (Centaurea spp.; see Forbs, Yellow Starthistle), native to southern Europe and southwestern Asia, are distinguished by long, sharp spines surrounding the flower head. Several related genera, such as Centaurea, Saussurea, and Cirsium, have species native to the United States that are similar to Carduus. Introduction History. Although musk thistle was brought to the eastern United States in the early 1800s, probably as a contaminant in ship ballast, it arrived in the midwestern states about 1900. It was recognized as a serious weed in the 1940s, and by the 1970s had spread to 42 states. Habitat. Musk thistle has a wide range of environmental tolerances, but does best in welldrained fertile alluvial soils, of any texture. It grows poorly on acidic or nutrient-deficient soils, but is somewhat tolerant of salinity. Although musk thistle grows in open natural areas, such as meadows, prairies, and deciduous forests, it heavily infests disturbed areas, such as sites subjected to landslides, flooding, fire, heavy grazing, or trampling. It is also frequently found in pastures, fields, annual grasslands, rangeland, roadsides and other rightof-ways, stream or ditch banks, and waste areas. It does not grow in very wet or very dry sites or in shade, and is absent from deserts, dense forests, and coastal environments. Although foliage is killed by a hard frost, the spiny stems remain erect. Musk thistle grows from sea level to 10,000 ft. (3,000 m) elevation. Reproduction and Dispersal. Musk thistle reproduces only by seed, and plants may be either cross-pollinated or self-pollinated. One plant can quickly become an infestation. The number of seed heads on each plant depends on site conditions, 1–18 on poorer sites, increasing to 24–46 on favorable sites. One 6 ft. (1.8 m) tall plant, however, had 643 seed heads! Plants will continue to flower and set seed until the soil moisture is depleted, producing more seeds in climates with spring and summer rainfall. One flower head can produce as many as 1,500 seeds, and one plant can produce as many as 120,000. The number of seeds per flower head decreases to as little as 25 later in summer. Most seeds fall within 165 ft. (50 m) of the parent plant, but some are transported long distances by wind, small mammals, birds, or water. The plumed seeds can be windblown for miles. Seeds become sticky when moistened, enabling them to adhere to surfaces. Human activity, involving farm animals, machinery, and vehicles, aids the spread of musk thistle seeds. Seeds may also be a contaminant in hay and crops. Although most seeds germinate within three years, some seeds remain viable in the soil for more than 10 years, enabling the plant to rapidly invade areas after a disturbance. Because seeds usually need a cool winter period, 40 days at temperatures below 50ºF (10ºC), in order to germinate, most seeds germinate from late summer to spring, in moist soils. Those that germinate in late fall may live as annuals and flower the subsequent summer. Although musk thistle reproduces only by seed, many buds on the root crown can sprout after the top portion of the plant is damaged. Impacts. Infestations of musk thistle degrade grasslands and inhibit succession. Plants frequently form large, dense colonies that crowd out native plants and suppress growth of forage plants by competing for light, nutrients, and moisture. Musk thistle is unpalatable to livestock and wildlife. Animals avoid grazing near the prickly plants, and selective grazing of native plant species decreases competition for the thistle. One plant per 16 sq. ft. (1 per 1.5 m2) can reduce pasture yields by more than 20 percent. Musk thistle has alleleopathic properties. Its seeds and dead leaves inhibit germination and growth of pasture grasses. At the bolting stage, the larger rosette leaves begin to decompose, possibly releasing inhibitors to other plants. Musk thistle threatens rare or sensitive species such as the Sacramento Mountain thistle in New Mexico and sand dune thistle, which is native to the sand dunes on the Great Lakes shoreline.

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In contrast, seeds are important feed for songbirds, and flowers are attractive to insect pollinators. Management. The best control is to maintain good range management and ensure that seed, hay, bedding, and equipment are clean of contaminants. Infected areas should be avoided. Care should be taken during any type of management to minimize soil disturbance, which triggers germination from the seedbank. Eradication may take 15 or more years. Because seedlings are intolerant of competition, reestablishment of native vegetation is effective. Physical control, such as mowing or burning, reduces seed production but will not eliminate infestations because new stems will emerge from the root crown. A single mowing is ineffective, because stands have plants of different heights and flower and seed development. Tilling, or any method which severs the root 2–4 in. (5–10 cm) below the soil surface, will kill plants but is not practical in crop or natural areas. Small plants in small populations can be hand-pulled all year, but pulling is best done before seeds develop. Any flower heads present should be bagged and disposed of to prevent seed dispersal. Chemical control will be only temporary if the conditions that caused the infestation are not changed. Preemergents are ineffective. Postemergence compounds, such as glyphosate, triclopyr, dicamba, 2,4-D, or picloram, work well when sprayed on foliage, especially when applied to the rosette stage in spring before flowering takes place. Chlorpyralid, which is selective to sunflower, buckwheat, and pea families, may harm crops. Because musk thistle reproduces only by seed, research for biological control has concentrated on seed-eating insects in southern Europe. Of the several species released in the United States, two have become established and are effective. A thistlehead-feeding weevil (Rhinocyllus conicus) was released in 1969. The insect hatches inside the flower head and feeds on developing florets. It works best where limited grazing allows grasses to compete with the thistles and can reduce thistle density by 90 percent in 5–6 years. It also attacks Scotch thistle. Because this weevil also feeds on several native Cirsium thistles, however, and can significantly reduce their seed production, its release in areas with Cirsium species requires extra care. A rosette-feeding weevil (Trichosirocalus horridus), which only occasionally feeds on native Cirsium species, was released in 1974. The larvae feed on meristem tissues in the rosette, causing the crown tissue to die. It can reduce musk thistle infestations by 96 percent within six years and works best in conjunction with Rhinocyllus conicus. It also attacks other Carduus species, such as Canada thistle, bull thistle, and Scotch thistle. The establishment of two other insects, a root-crown fly (Cheilosia corydon) and a thistle-rosette weevil (Psylliodes chalcomera), neither of which eat native Cirsium, is unknown. A second thistle-rosette weevil, Ceutorhynchus trimaculatus, was found to be destructive to native Cirsium species and was not released.

Selected References Gassmann, A., and L. T. Kok. “Musk Thistle (Nodding Thistle).” In Biological Control of Invasive Plants in the Eastern United States, by R. Van Driesche et al. USDA Forest Service Publication FHTET2002-04, Morgantown, WV, 2002. www.invasive.org/eastern/biocontrol/18MuskThistle.html. “Musk Thistle.” Plant Pest and Health Prevention Services (PHHPS), California Department of Food and Agriculture, n.d. http://www.cdfa.ca.gov/phpps/ipc/weedinfo/carduus.htm. “Musk Thistle (Carduus nutans L.) and Related Species.” Environment and Natural Resources Institute, Alaska Natural Heritage Program, University of Alaska, Anchorage, 2005. http://akweeds.uaa.alaska .edu/pdfs/potential_species/bios/Species_bios_CANU.pdf.

404 n FORBS Remaley, Tom. “Fact Sheet: Musk Thistle.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2005. http://www.nps.gov/plants/alien/ fact/canu1.htm. Zouhar, Kris. “Carduus nutans.” In: Fire Effects Information System, U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, 2002. www.fs.fed.us/ database/feis/plants/forb/carnut/all.html.

n Perennial Pepperweed Also known as: Tall whitetop, dittander, giant whiteweed, slender perennial peppercress, broadleaved pepperweed Scientific name: Lepidium latifolium Synonyms: Cardaria latifolia Family: Mustard (Brassicaceae)

n Hoary Cress Also known as: White top, perennial peppergrass, pepperweed whitetop, heart-podded hoary cress Scientific name: Cardaria draba Synonyms: Cochlearia draba, Lepidium draba, Nasturtium draba Family: Mustard (Brassicaceae) Native Range. Pepperweed is native to Europe, the northern coast of Africa, and Southwest and Central Asia, from Turkey and southwestern Russia to eastern China. Hoary Cress comes from Europe, European Russia, and Southwest and Central Asia, from Turkey to western China. Distribution in the United States. Pepperweed grows in coastal New England, midwestern and Great Plains states, from Illinois west to Nebraska, Kansas, and Texas, and in all states west of the Rocky Mountains. Especially invasive in the western states and still expanding its range. Hoary Cress grows in all states except in the Southeast. Most invasive west of the Rocky Mountains. Neither species is in Alaska or Hawai’i. Description. Perennial Pepperweed: Pepperweed is an herbaceous, perennial herb typically 1.6–5 ft. (0.5–1.5 m) tall, but it can reach more than 8 ft. (2.4 m) in height. The aerial parts die back to the soil surface in winter. Stems, very woody at the base, may remain erect for several years in dry areas, forming impenetrable thickets. New leaves emerge from the root in March, creating rosettes on the soil surface for several weeks before the plants bolt to flower. In late April, stems elongate quickly, and may reach 1.6 ft. (0.5 m) by June 1 and 3.3 ft. (1 m) by June 15, branching at the top. Leaves are glabrous and waxy, green to gray-green, sometimes with reddish spots. Leaves are elliptical and vary in size according to location on the plant. Rosette leaves, 4–12 in. (10–30 cm) long and 1–3 in. (2.5–8 cm) wide, have long petioles, 1.2–6 in. (3–15 cm), and serrate margins. Stem leaves are alternate, lance-shaped or oblong, and tapered at the base, with entire or slightly toothed margins. Leaf petioles become shorter with stem height, until leaves on the upper part of the stem are sessile. Leaves also become successively shorter up the stem. Both the rosette leaves and lower stem leaves senesce as the stems grow taller. Pepperweed has a large semi-woody root crown and many rhizomes, which are long, thick, and almost branchless. Although 20 percent of the root biomass is in the top 4 in.

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(10 cm) of soil, and 85 percent in the top 24 in. (60 cm), roots can extend more than 10 ft. (3 m) deep. Roots are phreatophytic, meaning that they grow down to the water table. Plants flower from May through August. Small, crossshaped flowers, about 0.1 in. (3 mm) wide, with four white petals form dense clusters on panicles, 5–6 in. (13–15 cm) wide, at the stem tips. The fruit, which matures in August and September, is a small, 0.08 in. (2 mm), two-chambered pod called a silicle. The silicle is round or slightly flattened, with long hairs. It is attached to the plant by a pedicel longer than the fruit. Each chamber produces one tiny reddish-brown seed, but stressed plants frequently abort the seeds. The fruit do not readily release the seeds and remain on the stem until the following spring. Stems become dried stalks in mid to late summer. Hoary Cress: Hoary cress is a smaller plant, an herbaceous perennial with erect stems growing 6–20 in. (15–50 cm) Perennial pepperweed grows best in wetlands and is often found along tall. Plants usually have one irrigation canals. (Native range adapted from USDA GRIN and selected stem, which may occasionally references. Introduced range adapted from USDA PLANTS Database, branch near the top. Basal Invasive Plant Atlas of the United States, and selected references.) leaves, growing in a rosette, are 1.5–4 in. (4–10 cm) long and lance-shaped. Stem leaves are smaller, 1.5–3 in. (4–8 cm) long, and broadly oval. They are alternate and sometimes have toothed margins. The stem leaves are sessile, and their broad bases clasp the stem. Both stems and leaves, blue-green to gray-green, are softly hairy at the base of the plant and become less hairy with height. Hoary cress has an extensive root system with abundant nutrient reserves. Rootstocks may extend 6 ft. (1.8 m) deep, and long rhizomes have numerous buds which create new shoots. Plants flower from April to June, and seeds mature from June to August. Flowers develop in terminal, branching racemes of flat-topped clusters. The four narrow, short petals forming a cross are white. Glabrous seed pods, called silicles, are heart-shaped at the base and supported by slender pedicels 0.2–0.6 in. (6–15 mm) long. Each flat silicle has 2–4 seeds.

406 n FORBS Related or Similar Species. Although 75 species of Lepidium, both annual and perennial, grow in North America, no natives grow aggressively or are invasive. Two alien invasive species of Cardaria can be distinguished by the shape of their seed pods. Lens-pod hoary cress has circular pods that are glabrous and fairly flat. Pods of hairy whitetop are spherical and covered with fine hairs. Introduction History. Pepperweed was accidentally introduced to California in the early 1900s, perhaps as a contaminant in sugar beet seed from Europe. It was first reported in Massachusetts in 1924 and in Connecticut in 1933, with an unknown source. Hoary cress was first recognized in California in 1876, probably introduced as a contaminant in ship ballast or alfalfa. Similar introductions took it to the southwestern United States in 1910 and to New York State in 1898. Habitat. Pepperweed is capable of growing in environHoary cress is invasive in sunny sites and in dry pastures and crops. ments as different as Donner (Native range adapted from USDA GRIN and selected references. Summit in the Sierra Nevada, Introduced range adapted from USDA PLANTS Database, Invasive Plant California, at 8,500 ft. (2,600 m) Atlas of the United States, and selected references.) and in the coastal salt marshes of San Francisco Bay. Although adapted to salinity and also found on salt pans in the Intermountain West, it does not require salty soils. It prefers wetlands, such as riparian areas, floodplains, and coastal marsh, but can also colonize seasonally dry meadows. It is often found in alfalfa fields, rangeland, native wet hay meadows with sedges and rushes, and along the irrigation canals and ditches that carry water to agricultural fields. Pepperweed does not grow in upland soils or where drought is prolonged. It dominates in areas that have been disturbed or are already weedy, such as roadsides, overgrazed pastures, and abandoned cropland. Although hoary cress is found in a variety of environments, it grows best in open, sunny grassland sites with neutral or alkaline soils. It is most often found on land disturbed by grazing or cultivation, such as fields, pastures, waste areas, and feed lots, and along roadsides and irrigation ditches. It is a more significant pest in the dry western states and is not as problematic in areas that receive higher rainfall. It is found at more than 8,000 ft.

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A. Stem leaves of perennial pepperweed are supported by petioles. (Joseph M. DiTomaso, University of California–Davis, Bugwood.org). B. Perennial pepperweed flowers grow in dense panicles. (Leslie J. Mehrhoff, Ecology and Evolutionary Biology University of Connecticut, Bugwood.org.) C. Pepperweed plants frequently form dense thickets. (Leslie J. Mehrhoff, Ecology and Evolutionary Biology University of Connecticut, Bugwood.org.) D. Stem leaves of hoary cress are sessile and clasp the stem. (Joseph M. DiTomaso, University of California–Davis, Bugwood.org.) E. Hoary cress flower clusters have flat tops. (Chris Evans, River to River CWMA, Bugwood.org.) F. Hoary cress seed pods are flattened pods with heart-shaped bases. (Joseph M. DiTomaso, University of California–Davis, Bugwood.org.)

(2,500 m) elevation in parts of the mountainous west and survives freezing temperatures and snowfall. Reproduction and Dispersal. Perennial Pepperweed: Pepperweed reproduces both sexually and vegetatively. Seed production is variable, perhaps in response to variations in seasonal rainfall. A mature root crown may produce several flowering stems. Although more flowers develop in dry years, each produces fewer seeds. One acre of plants can produce more than 6.5 billion seeds (16 billion per ha) every year. Seeds readily germinate in wet sand or mud, and seedlings can produce flowers and seeds in their first year of growth. Seedlings, however, are rare in dense infestations. Because the seeds have no hard coat, their viability is short term. Absence of a seed bank may account for the few seedlings found in the wild. Pepperweed creates large monospecific colonies from spreading rhizomes, and any small root piece will sprout a new plant. Root fragments can tolerate dry conditions, allowing them to be transported and become established elsewhere. Root fragments or seeds can be dispersed by water, or as contaminants in soil or hay bales, including those used for erosion control. Hoary Cress: Hoary cress is a prolific producer of seeds, 1,000–5,000 seeds per plant, with 80 percent viability. More seeds are produced in wet years, and seeds are viable for three years. They are dispersed in hay and forage, in soil adhering to farm equipment, or by water and wind. Such transport may be responsible for long-distance dispersal, but local infestations increase by rhizome extensions and sprouts. Stands rapidly increase in

408 n FORBS disturbed areas, and one plant can cover an area 12 ft. (3.6 m) in diameter after one year of growth. Root or rhizome pieces may also be carried long distances. Seedlings often appear after grass fires, which stimulate dormant seeds to sprout. Impacts. Closed-canopy thickets, with 4–8 stems per sq. ft. (40–80 per m2) of soil can obscure new spring growth of both pepperweed and other species. By sprouting from its root after the last spring frost, usually before native species emerge, pepperweed outcompetes native plants for moisture and nutrients as well as for light. The basal rosettes may persist all winter in regions with no frost. A dense litter layer, from old stems and leaves, can be deep enough, 4 in. (10 cm) or more, to block light and prevent emergence of native annuals. Even where pepperweed plants have been eradicated, the litter layer must also be removed to encourage sprouting of native species. Pepperweed plants interfere with regeneration of willows and cottonwoods, which is the normal succession on disturbed riparian sites. Because it is a phreatophyte, pepperweed roots pull salt as well as water from greater depths. The salt is then deposited on the surface, where it alters the soil chemistry and favors the growth of halophytes. Pepperweed displaces sedges and rushes in wetlands, which are important nesting sites for waterfowl and shorebirds. It also displaces endangered animal species, such as the salt marsh harvest mouse, a rodent endemic to the San Francisco Bay Area in California. Mixed in hayfields, pepperweed lowers the protein content of the hay used for livestock. Reports of horses being poisoned after ingesting pepperweed are being evaluated. Hoary cress can grow into extensive mats, to the exclusion of all other plants. It displaces forage and is toxic to livestock. Invasions of cropland reduce agricultural yields of grain, alfalfa, and orchard crops. Management. Eradication of pepperweed or hoary cress is difficult. The perennial roots may remain dormant in the soil for years, and sites must be continually monitored for early detection of new growth. Because plants are only green early in the season, they are easy to miss. Monospecific stands are most visible when plants are in flower or fruit. All root fragments must be removed or killed because even small pieces 1 in. (2.5 cm) long can grow into new plants. All litter must also be removed. No nonchemical management methods for pepperweed are effective except long-term flooding. It is not known, however, whether plants will reestablish after flooding subsides. Because pepperweed is most common on disturbed sites, it is important to restore the native vegetation to prevent re-infestation. Different management methods may be appropriate for large monospecific stands compared with smaller, scattered populations. Many physical control methods such as disking are inappropriate for native meadows or other natural environments. Other areas, such as marshes, riverbanks, and fencelines, also cannot be easily mowed or disked. Frequent mowing to maintain short stubble and prevent flowering is also not practical in natural environments. Although livestock will not eat pepperweed when the stems begin to elongate, the newly formed rosette leaves in early spring are palatable. Old stems may be mowed in pastures to expose the new growth for grazing. Grazing may control pepperweed growth, but plants recover when the grazers are removed. Any type of cultivation is usually inadvisable because it cuts rhizomes into small pieces that will resprout, resulting in stronger and larger root crowns. Although prescribed fires may be used to destroy the litter layer, release nutrients, and stimulate new growth, burning does not harm the root system of either pepperweed or hoary cress. Chemical applications of herbicides, such as 2,4-D, may kill the aerial parts of the plant, but new shoots will arise from the rootstocks the following spring. Repeated applications, however, may eventually deplete the root reserves. Herbicides are best when applied to

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flowerbuds in the early flowering stage. The most effective herbicide, chlorsulfuron, which both kills the foliage and remains in the soil to be absorbed by the roots, provides the best long-term control. Metsulfuron-methyl is more selective and does not harm grasses, but more research is needed. Imazapyr is also effective but is less selective, resulting in more bare ground. If the site is appropriate, mowing or disking at the flowerbud stage followed by herbicide application to new shoots is effective. Few herbicides are appropriate for use in the wetlands and riparian areas favored by pepperweed, and many are not approved for use on cropland. Glyphosate can be used in wetlands or riparian sites where other herbicides are prohibited. Sites treated with glyphosate rebound with better plant diversity than sites treated with other herbicides. Disking also aids diversity because it stimulates germination of the seed bank of other species. Herbicides applied in spring to areas that cannot be mowed or disked can simulate mowing by removing aerial parts of plants. Herbicides can then be applied to resprouts. Dormant, perennial roots require that the area be subjected to spot treatment for several years. Any biological control must be host-specific. The mustard family includes many valuable crops, such as canola, mustard, cabbage, and kale, and several Lepidium species native to the United States, which are threatened or endangered. Although white leaf rust (Albugo) decreases seed production of pepperweed in the western states, it does not harm the root system. Several insects eat the flowerbuds, which also decreases seed production, but the roots are unaffected.

Selected References Bossard, Carla, and David Chipping. “Cardaria draba.” In Invasive Plants of California’s Wildlands, edited by Carla C. Bossard, John M. Randall, and Marc C. Hoshovksy. Berkeley: University of California Press, 2000. http://www.cal-ipc.org/ip/management/ipcw. Howald, Ann. “Lepidium latifolium.” In Invasive Plants of California’s Wildlands, edited by Carla C. Bossard, John M. Randall, and Marc C. Hoshovksy. Berkeley: University of California Press, 2000. http://www.cal-ipc.org/ip/management/ipcw. Renz, Mark J., and J. M. Randall, eds. “Element Stewardship Abstract, Lepidium latifolium.” Element Stewardship Abstract. Global Invasive Species Team, Nature Conservancy, 2000. http:// wiki.bugwood.org/Lepidium_latifolium. Young, James A., Debra E. Palmquist, Robert S. Blank, and Charles E. Turner. “Ecology and Control of Perennial Pepperweed.” 1995 Symposium Proceedings, California Exotic Pest Plant Council. http:// www.cal-ipc.org/symposia/archive/pdf/1995_symposium_proceedings1795.pdf.

n Prickly Russian Thistle Also known as: Tumbleweed, Russian tumbleweed, saltwort, common saltwort, windwitch, witchweed, prickly glasswort Scientific name: Salsola tragus Synonyms: Salsola kali, S. australis, S. iberica, S. kali var. tenuifolia, S. kali ssp. tragus, S. kali ssp. ruthenica, S. pestifer Family: Goosefoot (Chenopodiaceae) Native Range. Semiarid steppes of southern Russia and western Siberia. Possibly native to the Caucasus region and Southwest Asia and as far east as Mongolia and northern China. Distribution in the United States. Every state except Alaska and Florida. Most invasive in western states.

410 n FORBS Description. Although the mature plant looks like a bushy shrub, prickly Russian thistle is a summer annual herb that reaches 1–5 ft. (0.3–1.5 m) tall and as much as 6 ft. (1.8 m) diameter. Seedlings and small plants resemble pine seedlings due to their finely-dissected, needlelike leaves. Subsequent young leaves are fleshy and soft, about 1 in. (2.5 cm) long, and only weakly spine tipped. Slender, flexible stems on juvenile plants are red or purple striped, either glabrous or pubescent. Immature plants are taller than they are wide, with lateral branches shorter than the main stem. Mature plants are usually equal in height and width. The plant’s many branches, which curve upward, become woody and spiny as the plants mature. Stalkless leaves, blue-green and alternate on the stem, are very narrow, 0.5–2.4 in. (1.3–6 cm) long, and awl-shaped or cylindrical. Leaves may be glabrous or covered with a short, stiff Dried plants of prickly Russian thistle, tumbleweeds, are commonly seen pubescence. Older leaves bein western states. (Native range adapted from USDA GRIN and selected come stiff and are succulent or references. Introduced range adapted from USDA PLANTS Database, sometimes leathery, usually Invasive Plant Atlas of the United States, and selected references.) with a pointed tip or spine at the end. Prickly Russian thistle has a large and spreading root system. Lateral roots are as long as 6 ft. (1.8 m), and the taproot extends 6 ft. (1.8 m) deep. Both types of roots enable the plant to draw moisture from a wide area. Plants usually bloom from July through October, although they will continue to flower and produce seed until temperatures fall below 25ºF (−4ºC). The inconspicuous small flowers grow solitary in leaf axils near the upper parts of the branches or in a terminal spike. They have no petals, but the five sepals are greenish, white, or pink. Two shiny, papery, awl-shaped bracts at the base of each flower are each tipped with a spine. Five stamens extend beyond the sepals. Flowers are wind pollinated, both crossing and self-fertile. The small fruit, 0.4 in. (1 cm), is enclosed in the calyx, which has five wing-like appendages, one from the back of each sepal. The fan-shaped sepal wings are translucent pinkish to deep red with minutely toothed margins. Each fruit contains only one seed. The dark

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A. Plants have a shrubby appearance but are herbaceous annuals. (Joseph M. DiTomaso, University of California–Davis, Bugwood.org.) B. Inconspicuous flowers, with sepals but no petals, grow in leaf axils. (Joseph M. DiTomaso, University of California–Davis, Bugwood.org). C. Seeds are dispersed as the dried plant, the tumbleweed, blows in the wind. (Richard Old, XID Services Inc., Bugwood.org.) D. Seedlings may be mistaken for tiny pine tree seedlings. (Phil Westra, Colorado State University, Bugwood.org.)

greenish-brown coiled embryo, or plantlet, is visible through the translucent seed coat. After flowering and setting seed, the plant dries completely. Related or Similar Species. The taxonomy for Salsola is confused, with no firm consensus on either scientific name or common name. S. tragus is possibly three or more similar species with different flower sizes and shapes. Several Salsola species are listed as noxious or invasive. First reported in 1958, slender Russian thistle is widespread, from the western intermontane basins east to the Midwest and New England, and is expanding its range. Slender Russian thistle seeds have been found as a contaminant in commercial bird seed. Plants grow to 3.3 ft. (1 m) tall, and stems have green and white striations. Dark green leaves, 2 in. (5 cm) long, on young plants are pliable, somewhat succulent to leathery, with a soft bristle at the tip. When those leaves are shed, they are followed by short, stiff, spiny leaves about 0.5 in. (1.25 cm) long. Bracts, which are lance-shaped and spine tipped, strongly overlap and completely cover the flowers and the fruit. Sepal wings are either absent or very narrow. Slender Russian thistle is a noxious weed in California. Barbwire Russian thistle closely resembles and is often confused with prickly Russian thistle, but is shorter, usually 1.6 ft. (0.5 m) tall. It rarely hosts the leafhopper, and is found in desert habitats, such as the Mojave Desert and east to Utah at elevations of 2,300–5,900 ft. (700–1,800 m). Although believed to have been introduced to the southwestern United States around 1900, it was not recognized until 1967. The immature plant is wider than it is tall, with lateral branches longer than the main stem. Stems are thick, somewhat rigid, with no purple striations. Leaves of barbwire Russian thistle, which do not differ between young and mature plants, are yellow-green, fleshy, thick, and stiff, with a spine at the tip. They are 0.2–1.2 in. (0.5–3 cm) long and often covered with short hairs. This species flowers 2–3 weeks before prickly Russian thistle does, and although flower bracts are similar, the sepal tips are stiff and spine like. Sepal wings resemble those of prickly Russian thistle but are larger. Barbwire Russian thistle plants do not become tumbleweeds, and most seed falls near the parent plant. Barbwire Russian thistle hybridizes with prickly Russian thistle, producing plants with intermediate characteristics.

412 n FORBS Oppositeleaf Russian thistle is a summer annual that grows to 1.6 ft. (0.5 m) on saline mudflats and saltmarshes in the San Francisco Bay area of California. The glabrous stems may be either green or red. The plant does not dry out but remains fleshy when mature. Flowers and fruit of shrubby Russian thistle are similar to those of prickly Russian thistle, but this species is a shrubby perennial. It has oblong to oval leaves with rounded tips, with no spines or sharp points. Halogeton (see Forbs, Halogeton), which grows less than 1 ft. (0.3 m) tall, can be mistaken for young prickly Russian thistle plants except for the cottony-white hairs in its leaf axils. Introduction History. Prickly Russian thistle was accidentally introduced to North Dakota in 1873 by Ukrainian immigrants as a contaminant in flaxseed. It spread rapidly, not only by its natural method of blowing in the wind, but also in contaminated seed, threshing machinery, and railroad cars. Removal of prairie grasses by farmers provided a smoother surface for the rolling dried skeletons. By 1900, prickly Russian thistle had reached the West Coast. Habitat. Prickly Russian thistle can be found anywhere the ground has been disturbed, including dryland agricultural fields, roadsides and other right-of-ways, pastures, river bottoms, forest edges, and vacant lots. It also invades sandy beaches and dunes, both inland and along the coast. It grows in a variety of soils, including alkali, but needs a loose texture and cannot establish on hard-packed substrate. The plant is very drought tolerant and is common in the semiarid western states, especially on overgrazed range and pasture. It will invade areas after dry spells or where vegetation has been cleared. It grows from below sea level in Death Valley to over 8,500 ft. (2,600 m) elevation. Reproduction and Dispersal. Prickly Russian thistle reproduces solely by seed, and one large plant typically produces 250,000 seeds. At maturity, the plant dries and breaks at the base. Seeds are dispersed as the skeleton ball of woody branches, called a tumbleweed, is blown by the wind. Often the path can be traced by a trail of seedlings that emerge the following spring. The tumbleweeds persist for at least a year, usually piled against an obstruction. Seeds usually remain viable for 6–12 months, and rarely for two years. Seeds germinate in spring under a wide range of temperatures, 28–110ºF (-2–43ºC). Most seeds germinate in March and April when temperatures are optimal, 45–95ºF (7–35ºC), but germination can occur all year if daytime temperatures are above freezing. Seedlings are easily killed by frost. Little rainfall (0.3 in. or 7.5 mm) is needed to stimulate germination, and seedlings develop a taproot within 12 hours. Because seeds have no protective coat, they have no stored food reserves. Each seed is a tiny embryonic plant, coiled inside a thin membrane, giving it the advantage of rapid growth. Impacts. Russian thistle is generally not competitive with other species. Seedlings are readily shaded out by other plants. It colonizes open ground, depending on rapid growth to gain access to deep soil moisture, thereby threatening reestablishment of native plant ecosystems. Infestations in agricultural land reduce crop yields, especially of alfalfa and small grains, by depleting soil moisture. Prickly Russian thistle is a host plant for the sugar beet leafhopper, a carrier for curly-top virus, which affects sugar beets, potatoes, tomatoes, and beans. Masses of tumbleweeds are a fire hazard. Entire plants can be carried by the wind as flaming balls, both spreading the fire and making firefighting dangerous. Large tumbleweeds blowing across highways are a hazard to drivers because they block vision and cause drivers to swerve to avoid the plant. Tumbleweeds may also block stream channels and roads. Management. Maintenance of rangeland and limiting disturbance is a key to prevention. Care should be taken to avoid loosening the soil in abandoned areas. Prickly Russian thistle is rarely a problem on well-tended sites where healthy stands of plants, such as perennial

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Russian Thistle as Food

B

efore they become woody and spiny, young plants are grazed by cattle and sheep. During the Dust Bowl in the 1930s, Russian thistle was fed to beef cattle because no other feed was available. Young Russian thistle is also a minor part of the diets of mule deer and elk, and tender shoots are important for bighorn sheep and pronghorn. Seeds are eaten by birds, such as Scaled Quail and Gambel’s Quail, and by many small mammals, such as prairie dogs and mice.

grasses, resist invasion. Plants may be successfully removed from one area, but unless the land is revegetated, adjacent regions provide a seed source for new invasions. Seedlings may be especially numerous along fences and other obstructions where plant skeletons accumulate, and all sites should be continually monitored for new infestations. Physical removal of large plants is difficult because of the spines. Although mowing large plants stimulates new branches to grow closer to the ground, repeated mowing may provide some control in reducing seed production. Plants may be cut, mowed, or tilled before seeds develop, but control must be repeated until the seed bank is depleted. Mowing is effective to eliminate seedlings. Burning is not an option because Russian thistle thrives on disturbed sites. Chemical control is most effective in the seedling stage. Different herbicides should be selected for different types of sites, such as roadside versus crop or pasture. Several preemergents are effective if used along roadsides in the fall. Postemergents, such as dicamba, glyphosate, triclopyr, and others, are more effective on seedlings than on mature plants. Few herbicides will kill plants after they reach the spiny stage. The herbicide 2,4-D causes plants to become tough and leathery, making them even more difficult to manage. Several applications may be necessary as seedlings continue to emerge throughout the spring and summer. Because populations may develop resistance to specific herbicides, changing types is recommended. Biological control has had limited success. Two insects, a leaf-mining moth (Coleophora klimeschiella) and a stem-boring moth (C. parthenica), released in the 1970s, did not provide sufficient control. The host-specific blister mite (Aceria salsolae) from the Mediterranean region stunts plants by killing the growing tips of young stems, preventing the development of flowers. It attacks only S. tragus and its close relatives. Other possibilities include a moth (Gymnancyla canela), whose caterpillers eat developing seeds and stems. Central Asia is being explored for other natural enemies.

Selected References Morisawa, Tunyalee. “Element Stewardship Abstract, Salsola kali.” Global Invasive Species Team, Nature Conservancy, 1988; modified 2009. http://wiki.bugwood.org/Salsola_kali. Orloff, S. B., D. W. Cudney, C. L. Elmore, and J. M. DiTomaso. “Pest Notes: Russian Thistle.” UC ANR Publication 7486. Agriculture and Natural Resources, Statewide IPM Program, University of California, Davis, 2008. http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7486.html. “Salsola genus Part 1, Russianthistle or Common Russianthistle, Spineless Russianthistle, Barbwire Russianthistle.” Plant Pest and Health Prevention Services (PHHPS), California Department of Food and Agriculture, n.d. http://www.cdfa.ca.gov/phpps/ipc/weedinfo/salsola.htm.

414 n FORBS Smith, Lincoln. “Biological Control of Russian Thistle (Tumbleweed).” Proceedings of the 60th Conference of the California Weed Science Society, Monterey, CA: 90-93, January 28–30, 2008. http://www.cwss.org/proceedingsfiles/2008/90_2008.pdf.

n Purple Loosestrife Also known as: Purple lythrum, rainbow weed, salicaire, spiked loosestrife Scientific name: Lythrum salicaria Synonyms: None Family: Loosestrife (Lythraceae) Native Range. Eurasia, including all of Europe and east through China and Korea to Japan. Also from the northern coast of Africa. Distribution in the United States. All of the United States except Florida, Alaska, and Hawai’i. The heaviest infestations are in the northeastern states, where continental glaciation left abundant wetland sites. West of the Mississippi River, where territory is generally dryer, distribution is scattered and primarily found around water reclamation projects. Description. Purple loosestrife is an erect perennial herb, 1.5–10 ft. (0.5–3 m) tall, with 4–7 stems per plant. Green to purple stems are square or octagonal, often branching to make the plant bushy. Leaves are opposite or in whorls of three, which seem to clasp the stems. Leaves are stalkless, lance-shaped to oval, 1.5–2.3 in. (4–6 cm) long, and heart-shaped or rounded at the base. Leaf edges are entire, not toothed or lobed. Plants are covered with fine hairs. Leaves on the aerial shoots die back in fall, but the woody stems remain erect for 2–3 years, contributing to the density of the stand. New shoots in spring emerge from the rootstocks, not from the dead aerial shoots. Purple loosestrife has both a taproot and spreading rootstock. Mature plants may grow 30–50 stems from one rootstock. The large woody taproot with rhizomes forms a dense mat in the soil. Very showy purple or magenta flowers, with 5–7 petals each 0.4 in. (1 cm) long, develop all summer, from June to September. They are arranged in whorls on terminal spikes which are as small as 3 in. (7.5 cm) or as tall as 3 ft. (1 m). The calyx of each flower is tubular and hairy, with 12 thin vertical ridges on the outside. Flowers may also be light pink or white. The fruits, or seed capsules, which remain on the plant during winter, are 0.1 in. (3–4 mm) long. Each capsule contains an average of 120 tiny seeds, with 900 seed capsules per plant. Related or Similar Species. Cultivars of purple loosestrife and European wand loosestrife vary little from the wild plant and can still be purchased from nurseries. Although labeled as “infertile,” they produce viable seed and cross freely with non-cultivars of purple loosestrife and native Lythrum species. European wand loosestrife is a perennial subshrub that reaches 20–40 in. (50–100 cm) tall. Its glabrous stems distinguish it from purple loosestrife. Leaf bases are wedge shaped, and leaf margins are coarsely toothed. It also has fewer flowers, only 2–3 per stem. Because of the showy flower spike, purple loosestrife can be confused with native flowers, such as fireweed, swamp verbena, Canada germander, or blazing star, when viewed from a distance. Close examination, however, will reveal distinct differences for positive identification. Introduction History. First reported in North America in 1814, purple loosestrife was intentionally brought to the United States in the early 1800s for both ornamental and herbal

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uses, and also inadvertently in ship ballast. The plant spreads rapidly via canals and other water transportation systems. Habitat. Purple loosestrife is a riparian plant, inhabiting freshwater wetlands such as lakeshores, marshes, wet meadows, river and stream banks, and pond, reservoir, or ditch edges— areas that would naturally support cattail marshes, sedge meadows, and bogs. Because of its massive seed output and seed bank, purple loosestrife quickly reseeds and grows onto disturbed or degraded wetland sites, such as exposed banks during dry years, or where bulldozing, silt deposition, cattle trampling, or dredging have created bare surfaces. When not found in homogenous stands, purple loosestrife grows in association with broadleaf cattail, white cattail, common reed (see Graminoids, Common Reed), cordgrass, bulrushes, and sedges. The plant tolerates many environmental conditions, but its one requirement is moisture. It grows best in soils with high organic content but is found on a Purple loosestrife, with attractive purple flower spikes, commonly grows wide range of substrate, including in wet sites around lakes and marshes. (Native range adapted from clay, sand, muck, and silt. Al- USDA GRIN and selected references. Introduced range adapted from USDA PLANTS Database, Invasive Plant Atlas of the United States, and though full sun is preferred, plants selected references.) survive in 50 percent shade. Reproduction and Dispersal. Although the plant resprouts from root and stem fragments, its major means of reproduction and spread is by seed. Attracted by abundant nectar, several types of bees and butterflies pollinate the flowers. Because purple loosestrife has a long flowering season, the top of the spike is often still in flower while the lower seed capsules are mature. A large plant from a single rootstock can produce 2–3 million seeds per year. Plants in open areas produce more seeds than plants in dense stands. When ripe during June to September, the seed capsules burst, expelling the seeds. Seeds may remain viable for 20 years. Ability to germinate, however, decreases after two years of storage in water. The buoyant seeds are disseminated primarily by wind and water, but also by birds, animals, and humans. Seeds often are embedded in mud on the feet of waterfowl and other animals or carried on clothing. Beekeepers have been known to deliberately sow seed in order to have a good source of nectar.

416 n FORBS

A. Lance-shaped leaves are opposite on the stem. (Steve Dewey, Utah State University, Bugwood.org.) B. Three whorled leaves clasp the stem. (Ohio State Weed Lab Archive, The Ohio State University, Bugwood.org.) C. The inflorescence is a terminal spike. (Eric Coombs, Oregon Department of Agriculture, Bugwood.org.) D. The purple flowers are showy. (Norman E. Rees, USDA Agricultural Research Service, Bugwood.org.)

Seeds can germinate in any type of soil, acid to alkaline, rich or poor in nutrients. Soil surface temperature of 59–68ºF (15–20°C), however, is critical. Established seedlings can survive standing water up to 12–18 in. (30–45 cm) deep. As many as 1,000–2,000 seeds can germinate in a single square foot (10,000–20,000 per m2), outcompeting native seedlings. As they grow, the plants crowd out or shade out native species. Germination can take place in either spring or summer, but spring germinators have a better chance of survival. Taproots grow rapidly when plants are seedlings. New plants can flower only 8–10 weeks after germination. Plants that germinate in spring can produce a 12 in. (30 cm) inflorescence the first year. The rhizomes increase the size of stands by growing about 1 ft. (0.3 m) each year. Any stem cutting or piece of root will sprout. Impacts. Purple loosestrife invades both natural and disturbed wetlands, where it replaces native plants and threatens the existence of rare and endangered species, such as orchids. Its aggressive growth displaces grasses and sedges, which provide better nutrition for wildlife. Redwing Blackbirds, however, have been noted to eat purple loosestrife seeds. Species diversity is replaced with homogenous stands of purple loosestrife. Dense thickets restrict access to open water and limit food and shelter for wildlife, particularly waterfowl, because the thickets are unsuitable for either nesting or forage. Dense stands clog waterways, irrigation ditches, and recreational water bodies, and can alter hydrology of moist meadows. Debris builds up around the roots, enabling plants to invade deeper water and shade out native emergent vegetation or eliminate floating vegetation by clogging waterways. Management. Depending on objectives and available funds and personnel, purple loosestrife can be prevented, contained, or even eradicated. It is difficult to impossible to totally eradicate stands of three acres (1.2 ha) or more. Because the most effective herbicides are nonselective and biological controls are still experimental, containment and minimizing reproduction are more feasible goals than eradication. Physical means such as hand-pulling, with as little disturbance to the soil as possible, may be effective on small stands or at the edges of larger stands to prevent spread. Root disturbance stimulates growth, and because any fragment will grow a new plant, all pieces must be removed. Pulling or digging out plants before seed production also limits seed supply.

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It is more difficult to control large populations. Frequent cutting to ground level over several years may deplete root reserves and weaken the stand. All cuttings and fragments should be burned so they cannot sprout. Burning plants without first cutting them down makes infestations worse because desirable plants are also destroyed and purple loosestrife resprouts from the root when aerial parts are damaged. Systemic herbicides such as glyphosate and triclopyr offer effective chemical control, but sites require frequent monitoring for regrowth. Treatment is best done late in the season when plants are pulling nutrients into the root system in preparation for dormancy, although midsummer applications can reduce seed production. Because these nonselective herbicides also kill native vegetation, purple loosestrife can actually increase due to its abundant seed production and new exposure of bare sites. If possible, spot treatment is best, on stems cut down to 6 in. (15 cm). Follow-up is critical to prevent new growth, both during the same growing season and for several years after treatment. Some plants survive, some are missed, and new plants sprout from the seed bank. For large areas where spot treatment is not feasible, spray with a broadleaf contact herbicide, such as 2,4-D. Most native wetland plants are monocots and will not be harmed. Results are best when spraying is done in late May or early June, but purple loosestrife may not be seen without its showy flowers. Long term control of purple loosestrife requires biological methods. Three insect species from Europe, approved by the U.S. Department of Agriculture in 1997, were released in selected natural areas in northern states from Oregon to New York. They include a rootmining weevil (Hylobius transversovittatus) and two leaf-feeding beetles (Galerucella calmariensis, G. pusilla), which do not appear to substantially harm other plants. Experiments are being conducted with flower-feeding beetles. Some success has been achieved by replacing purple loosestrife with other plants. When sown on newly emerged bare soil, Japanese millet (Echinochloa frumentaceae) can outcompete purple loosestrife as long as its seeds have not begun to germinate. The Japanese millet must be resown every year. Native curlytop knotweed (Polygonum lapathifolium) has provided similar results when sown into existing purple loosestrife stands.

Selected References Bender, J. “Element Stewardship Abstract, Lythrum salicaria.” Global Invasive Species Team, Nature Conservancy, 1987. http://www.invasive.org/gist/esadocs/documnts/lythsal.pdf. “Purple loosestrife, Lythrum salicaria L.” Weed of the Week. U.S. Department of Agriculture, Forest Service, Invasive Plants, n.d. http://www.na.fs.fed.us/fhp/invasive_plants. Swearingen, Jil M. “Purple Loosestrife.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2005. http://www.nps.gov/plants/alien/fact/ lysa1.htm. Zheng, Hao, Yun Wu, Jianquing Ding, Denise Binion, Weidong Fu, and Richard Reardon. “Lythrum spp. Loosestrife.” Invasive Plants of Asian Origin Established in the US and Their Natural Enemies, 2004. http://www.invasives.org/weedcd/pdfs/asianv1/lythrum.pdf.

n Spotted Knapweed Also known as: None Scientific name: Centaurea stoebe Synonyms: Centaurea biebersteinii, C. maculosa Family: Sunflower (Asteraceae)

418 n FORBS Native Range. Central Europe to southwestern Russia, including the Caucasus region Distribution in the United States. Widely distributed, with the exception of Oklahoma, Texas, Alaska, and Hawai’i. Description. Spotted knapweed is a biennial or short-lived perennial with a basal rosette of leaves, erect branching stems, and a deep taproot. Foliage is gray-green and hairy. Plants usually live 3–9 years and resprout from the root crown. During the first year of growth, the plant develops a basal rosette, sending up flowering stems in subsequent years. Rosette leaves are long and narrow, 8 in. (20 cm) by 2 in. (5 cm), wider above the middle half and narrower toward the base. They grow on short stalks. Rosette leaf edges are deeply lobed or wavy, and leaf surfaces are rough. Flowering stems, growing 1–4 ft. (0.3– 1.2 m) tall, are slender, multibranched, and either sparsely or densely hairy. The pale-green stem leaves are alternate and As a contaminant in alfalfa seed, spotted knapweed rapidly became stalkless. Margins of the lower widespread in the United States. (Native range adapted from USDA GRIN stem leaves are slightly lobed, and selected references. Introduced range adapted from USDA PLANTS while the upper leaves are Database, Invasive Plant Atlas of the United States, and selected references.) linear and entire. Stem leaves are 1–3 in. (2.5–7.5 cm) long, decreasing in size toward the tip of the stem. Plants bloom from June to October, with a shorter flowering time in more northern climates. Each plant produces 1–15 flowering stems. Flower heads, which may be solitary or in groups of 2–3 at the ends of each branch, are 0.25 in. (6 mm) in diameter and 0.5 in. (12.5 mm) long. Several, 25–35, pink or lavender (rarely white) tubular florets are clustered on each head. Although seeds are shed when mature, the dry flower heads remain on the plant. The yellow-green bracts at the base of the flower have obvious veins and are tipped or spotted in black, giving the plant its name. Plants with white flowers usually lack the black spots. Margins of the bracts are fringed with soft spines. The pale-brown seeds are oval and tiny, less than 0.25 in. (6 mm) long, with a short fringe of light-colored bristles or spines on one end. Related or Similar Species. Several similar knapweeds and starthistles cause similar environmental problems. Russian knapweed is a creeping perennial with black, scaly roots

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A. Stems are freely branching. B. Rosette leaves are deeply lobed. C. Bracts at the base of the flowerhead are distinctly spotted with black. (Steve Dewey, Utah State University, Bugwood.org.)

extending as deep as 8 ft. (2.5 m). Young plants in the spring are a rosette of silvery-green hairy leaves with wavy edges, and flower stalks support pink or lavender cone-shaped flower heads. Found on sites similar to where spotted knapweed invades, it can be distinguished by its flower heads, which are smaller and lack the black spots. Russian knapweed is also alleleopathic, exuding toxins that prevent growth of competitors. It reproduces not only from seed, but also vegetatively. Any piece of root will sprout a new plant, even from 3 ft. (1 m) deep or under a plastic cover. Herbicide applications kill only the aerial portion of plants. The plant is toxic to some animals, especially horses, which can die if they ingest too much. Cattle and sheep are not affected. Diffuse knapweed, a biennial growing 1–3 ft. (0.3–1 m) tall, has white, pink, or pale-purple flowers, with 12–13 florets per head. Stem leaves are linear and entire. Straw-colored spines are short, only 0.1 in. (3mm) long. The plant is self-fertile, producing about 13 dark-brown seeds per flower head. Seeds are dispersed when the flower stems break and blow away in the wind. Squarrose knapweed is a shorter perennial, 1.6 ft. (0.5 m) tall, with a woody base and a stout taproot. Stem leaves are also linear and entire, although plants usually have no stem leaves when they are in flower. It has 4–8 pink to pale-purple florets per head. The short, 0.01 in. (3 mm), central spines on the bracts are usually tilted downward. Each flower head produces 1–4 pale brown seeds, and the head falls as a unit from the plant. This species is more adaptable to drought and cold conditions. Purple or red starthistle is an annual or perennial, growing as tall as 3 ft. (1 m). Its leaves are resin-dotted, and the upper stem leaves are lobed or divided. New rosette leaves are densely covered with gray hairs, and the rosette develops a circle of spines as it ages. Flowers are distinctly reddish purple, and the thick, straw-colored spines on the bracts are 0.5–1 in. (1.3–2.5 cm) long. It grows a stout taproot and is frequently found on heavy, fertile, or alluvial soils. The seeds are white, and the seed head falls as a unit from the plant. Iberian knapweed is an annual, biennial, or short-lived perennial that resembles purple starthistle except for its pale rose-pink or whitish flowers. Its leaves are resin-dotted, and the stem leaves are pinnately divided. Spines are shorter than those of purple starthistle. New leaves are covered with tiny bristly hairs. Its seeds are white. It has a stout taproot and is common along water course banks and other moist sites. Introduction History. Spotted knapweed was accidentally introduced to the United States from eastern Europe in the late 1800s or early 1900s as a contaminant in alfalfa or clover seed. Alternatively, the seeds may have been in soil used as ship ballast. First recorded in British Columbia in 1883, the plant spread rapidly in seed shipments before it was noticed to be an invasive problem.

420 n FORBS Habitat. Spotted knapweed has wide environmental tolerances. It grows from sea level to over 10,000 ft. (3,000 m) elevation and in regions with 8–80 in. (200–2,000 mm) of precipitation. An invader of both disturbed and natural land in many habitats, it grows predominantly in semiarid rangeland and pasture. It is also found in forest clearings, irrigated areas, and agricultural fields. It grows best on well-drained soils with summer rain, and does not compete well in moist areas. In seasonally dry areas, its deep taproot gives it an advantage over other plants, enabling it to access deeper water sources. It is most invasive in disturbed areas, such as gravel pits, vacant land, hayfields, and along highways, railroad tracks, pipelines, utility lines, and waterways. Reproduction and Dispersal. Spotted knapweed reproduces only by seed, 1,000 or more per plant. Plants can produce 500–4,000 seeds per sq. ft. (5,000–40,000 per m2) of ground each year, of which 90 percent are immediately viable the same or following season. The rest of the seeds remain in the soil for 5–8 years and can re-infest a site after the initial plants have been destroyed. Germination takes place during the entire growing season, from spring to fall. Seedlings that sprout in the fall overwinter as rosettes, resuming growth to produce flowering stems in subsequent years. Most seeds fall close to the plant and are dispersed short distances by animals, in fur and in droppings, and by water. Because seeds have no adaptations for long-distance dispersal, the plant is dependent on human influence to spread to new territory. Seeds can be carried by livestock, on vehicles, or as contaminants in crop seed or hay. Spotted knapweed spreads easily from gravel pits, equipment or machine yards, grain elevators, fill dirt piles, logging yards, and railroad yards. Although the root crowns may sprout stems, the plant does not reproduce vegetatively. Impacts. Spotted knapweed infests several million acres in the United States. Because it is alleleopathic, exuding a chemical that prevents other plants from growing nearby, it can create a monoculture. It outcompetes native species, reducing biodiversity of both plants and animals, and decreases forage potential of rangeland. Economic impact due to loss of forage is estimated to be in the millions of dollars. The taproot replaces intertwined native grass roots, reducing both the stability of the soil and its water-holding capacity. Dense infestations contribute to soil erosion and sedimentation caused by increased runoff. The plants also lessen the visual attractiveness of recreational lands, and dry plants pose a fire hazard. Management. The most effective means of control is to prevent the spread of seeds. Livestock grazing should be limited when seeds are ripening. Clothing, all hiking gear, vehicles, and equipment should be thoroughly cleaned. Transport of potentially contaminated hay should be prevented. Existing infestations are best controlled by using a combination of physical, chemical, and biological means. Competitive range plants, both grasses and forbs, may help control spotted knapweed, but revegetation or reseeding is best done when the spotted knapweed is stressed from prior treatments. Control of small infestations may be attempted by physical means, such as hand-pulling plants before seed sets. The entire root crown and taproot must be pulled out to prevent resprouting. For best results, the area should be treated with a herbicide after hand removal. Mowing stems before they flower can reduce seed production, and long-term grazing by sheep and goats is sometimes successful in suppressing infestations. Livestock will eat it when nothing else is available. Chemical means of control have met with limited success. Herbicide applications that control all plant stages, including mature plants, seedlings, and seeds in the soil, are best. Because of the long-term viability of seeds in the soil, reduction in the seedbank should be a goal. The herbicide 2,4-D will kill existing plants, but needs to be reapplied yearly to eliminate seedlings that sprout from the soil seed bank. Picloram can control seedling growth for

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2–5 years, but may contaminate groundwater in porous soils or in areas with a shallow water table. Dicamba is less effective than picloram in preventing seed germination and also kills other broadleaf plants. Although clopyralid is also effective in controlling spotted knapweed and is a more selective herbicide; it will harm clovers, which are often desirable range plants. The best times for herbicide application are on the rosettes in the fall and at the bud or bloom stage in spring. Although it may take decades to suppress or kill spotted knapweed on a large site, biological control, using several insects from the plant’s native range in Eurasia, is most efficient for extensive infestations. Insect larvae from spotted knapweed’s natural enemies feed on and damage the root, leaves, or flowers. From 1973 to 1992, 12 insects from Eurasia have been released in North America. Insects selected for biological control are host-specific and should not affect native plants. Although impact on natives has not been researched, no incidences have been reported of nontarget plant species being attacked. Several species are well established, with individual success related to location and climate. Especially effective are two seed head flies (Urophora affinis and U. quadrifasciata), which can reduce seed production by 50 percent. Larvae of a seed head weevil (Larinus minutus) and a moth (Metzneria paucipunctella) also damage growing seeds. Larvae of a root-boring weevil (Cyphocleonus achates) burrow into roots and feed all winter, spring, and early summer, depleting the plant’s resources. Insects weaken plants and reduce their competitive ability. Economic benefits are not yet realized, but reductions in knapweed have been observed. Research is ongoing, with no definitive results, but a combination of insects for biological control appears to be more effective than just one species.

Selected References “Centaurea Genus Part I.” Plant Pest and Health Prevention Services (PHHPS), California Department of Food and Agriculture, n.d. www.cdfa.ca.gov/phpps/ipc/weedinfo/centaurea.htm. Lym, Rodney G., and Richard K. Zollinger. “Spotted Knapweed (Centaurea maculosa Lam.).” North Dakota State University Extension Service, Fargo, ND, 1992. http://www.ag.ndsu.edu/pubs/ plantsci/weeds/w842w.htm. “Russian Knapweed.” Colorado State University Cooperative Extension Tri River Area, Grand Junction, CO, 2004. http://www.coopext.colostate.edu/TRA/knapweed.html. “Spotted Knapweed, Centaurea biebersteinii DC.” Chequamegon-Nicolet National Forest, U.S. Department of Agriculture, Forest Service, 2005. http://www.fs.fed.us/r9/cnnf/natres/nnis/spotted _knapweed.html. Story, J. “Spotted Knapweed.” In: Biological Control of Invasive Plants in the Eastern United States, by R. Van Driesche et al. U.S. Department of Agriculture, Forest Service Publication FHTET-2002-04, Morgantown, WV, 2003. http://www.invasive.org/eastern/biocontrol/13Knapweed.html.

n Toadflax Dalmatian Toadflax Also known as: Broadleaf toadflax, broad-leaved toadflax, wild snapdragon Scientific name: Linaria dalmatica ssp. dalmatica Synonyms: Linaria genistifolia ssp. dalmatica Family: Figwort (Scrophulariaceae)

422 n FORBS Yellow Toadflax Also known as: Common toadflax, wild snapdragon, perennial snapdragon, flaxweed, butter and eggs, eggs and bacon, Jacob’s ladder, rabbit-flower Scientific name: Linaria vulgaris Synonyms: None Family: Figwort (Scrophulariaceae) Native Range. Dalmatian toadflax is native to the Mediterranean region of southeastern Europe, extending into Turkey and Afghanistan in Southwest Asia. Yellow toadflax is native to central and southern Europe and to Turkey. It may also be native to the British Isles, Russia, Siberia, and China. Distribution in the United States. Dalmatian toadflax is common in the northern states, but is problematic in the Rocky Mountain and western desert regions. It is not found in Alaska, Hawai’i, or in the southeastern states. With the exception of Hawai’i, yellow toadflax is found throughout the United States, including southern Alaska. It is more comDalmatian toadflax is found on coarse-textured, well-drained soils, premon in eastern North America dominantly in western states. (Native range adapted from USDA GRIN and selected references. Introduced range adapted from USDA PLANTS and is scattered in the West. Description. Toadflaxes are Database, Invasive Plant Atlas of the United States, and selected references.) short-lived herbaceous perennials that grow 1–25 vertical flowering stems, which are thick-walled and fibrous. Although leaves are alternate, crowding on the stem may make them appear to be opposite. Plants have both a long taproot, usually 4 ft. (1.2 m) deep into the soil, and creeping horizontal roots, at a depth of 2–12 in. (5–30 cm), which can grow as far as 12 ft. (3.6 m) from the parent plant. Flowers, which resemble snapdragons, develop from May to August. They are bright yellow, with a distinctly two-lipped yellow corolla. A bulge in the lower lip, called the palate, which almost closes the throat of the flower, is hairy and orange. Because flowers mature successively from the lower stem to the top, several stages of flower and fruit can be on one plant or inflorescence. Fruits are two-celled capsules, which grow upright on the stem. Seeds mature from July to October. Dalmatian Toadflax: Dalmatian toadflax stems grow to 2–5 ft. (0.6–1.5 m) tall, and are stiff and leafy. Plants are usually scattered rather than clumped, although they may be

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connected beneath the surface. Plants are robust, with waxy stems that branch toward the top of the plant. The stems become rough and woody at the base, while the upper portions are smooth and more herbaceous. Plants develop prostrate stems in September, which are tolerant to freezing and remain green beneath the snow in winter. These branches give rise to floral stems the following summer. The lower leaves, oval or heart-shaped and pointed, are 1–2.5 in. (2.5–6 cm) long and almost as wide. They wrap around or clasp the stem. Upper stem leaves are smaller and oval to lance-shaped. All leaves are bluish green and waxy. Flowers develop in long, loose racemes at the ends of the stems, with each flower supported by a short pedicel growing from a leaf axil. Flowers are 0.5–1 in. (1.4–2.5 cm) long, with a curved spur, 0.4–0.7 in. (1– 1.7 cm) long. Each egg-shaped to round fruit capsule, approximately 0.2–0.4 in. (4–10 mm) Yellow toadflax, growing in moist sites, is common in the eastern states in diameter, contains 60–300 and a frequent invader of cropland. (Native range approximated from seeds. The small, 0.04–0.08 in. USDA GRIN and selected references. Introduced range adapted from USDA PLANTS Database, Invasive Plant Atlas of the United States, and (1–2 mm), black seeds are selected references.) sharply triangular, with a slight papery wing on each edge. Dead flower stalks may remain standing for 2 years. Yellow Toadflax: Yellow toadflax is a shorter plant, with smooth stems 1–3 ft. (0.3–1 m) tall, growing in crowded patches or clumps. Stems are generally sparsely branched or not at all. They are usually reddish at the base, and become more slender and green toward the tips. The pale-green leaves are linear to lance-shaped, 1 in. (2.5 cm) long and less than 0.2 in. (0.5 cm) wide, pointed or tapering at both ends. They are sessile, do not clasp the stem, and are not waxy. Yellow toadflax does not produce overwintering prostrate stems, and all above-ground parts die back in winter. Flowers of yellow toadflax form in dense terminal clusters of 6–30, which continue to grow and become longer as new flowers develop. Flowers are approximately 1 in. (2.5 cm) long, including the short spur. Each stem may have as many as 30 globular seed capsules, each containing as many as 250 seeds. Yellow, dark-brown, or black seeds, 0.04–0.08 in. (1–2 mm), are flattened disks, with a distinctly winged edge.

424 n FORBS

A. Heart-shaped leaves on prostrate stems of Dalmatian toadflax wrap around the stem. (Bonnie Million, BLM, Ely District, Bugwood.org.) B. Upper stem leaves of Dalmatian toadflax are lance-shaped. (Steve Dewey, Utah State University, Bugwood.org.) C. Dalmatian toadflax flowers grow in loose racemes. (Joseph M. DiTomaso, University of California–Davis, Bugwood.org.) D. Pedicels of Dalmatian toadflax flowers emerge from leaf axils. (Joseph M. DiTomaso, University of California–Davis, Bugwood.org.) E. Yellow toadflax plants are shorter than those of Dalmatian toadflax. (L. L. Berry, Bugwood.org.) F. Sessile leaves of yellow toadflax are linear and do not clasp the stem. (Bonnie Million, BLM, Ely District, Bugwood.org.) G. Yellow toadflax flowers grow in dense terminal clusters. (Steve Dewey, Utah State University, Bugwood.org.) H. Yellow toadflax flowers grow close to the stem. (Richard Old, XID Services, Inc., Bugwood.org.)

Related or Similar Species. Because Dalmatian toadflax and yellow toadflax are highly variable in shape, size, and color, hybrids may have developed between the two. A possibility exists that the narrow-leaf form of Dalmatian toadflax is a separate invasive from Europe, broomleaf toadflax. Canada toadflax, also called blue toadflax, is native to the United States and easily distinguished by its purple or blue flowers. Introduction History. Both species of toadflax were introduced as ornamentals because of their showy flowers. Yellow toadflax, a plant used in Germany for yellow dye, was brought to Delaware from Wales in the mid-1800s. Immigrants, especially Mennonites, cultivated it for dying yarn and cloth. Dalmatian toadflax was brought to the western United States in the late 1800s. Widely available in the horticultural trade under several names, toadflaxes are still used as garden plants. Habitat. Toadflaxes are quick to invade bare areas, especially when perennial plants are removed. Because the taproot efficiently taps deep moisture, toadflaxes are well adapted to arid sites and are most competitive in dry-summer climates. Both species prefer sunny sites, tolerate low temperatures, and thrive in open, disturbed habitats. Dalmatian toadflax does best on well-drained, coarse-textured soils, such as road and railroad rights-of-way, gravel pits, waste areas, abandoned lots and fields, clear cuts, and degraded rangelands. It also grows in low-elevation coniferous forests and with oak and aspen at 5,000–6,500 ft. (1,500–2,000 m) elevation. Although generally found on similar soils and sites, yellow

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toadflax requires more fertile soils with more moisture, and can invade higher elevations, such as upland meadows at 6,000–8,500 ft. (1,800–2,600 m) elevation. It is also a more common weed in cropland. Reproduction and Dispersal. Both species reproduce both sexually and vegetatively. Infestations usually start by seed, but expand from the root system. Both species require cross-pollination with another plant, usually done by large bees. Although most seeds drop from the plant in the year they mature, some seed may remain on the dead stem. One Dalmatian toadflax plant can produce as many as 500,000 seeds in a season, with 75 percent germination. Yellow toadflax, is less prolific, as many as 30,000 seeds per plant, with a germination rate of 10 percent. Yellow toadflax capsules that mature later in the season, however, have a higher percentage of viable seeds. Wind is the primary dispersal agent for the winged seeds, which can even be blown across encrusted snow. Broken stalks may be blown as a unit. Seeds are also dispersed by livestock, deer, and other browsing animals. Seeds, which may remain viable in the soil for as long as 10 years, germinate in both fall and spring. Seedlings, with lance-shaped leaves in both species, grow rapidly. Dalmatian toadflax may develop a 20 in. (50 cm) long taproot within eight weeks and 2–5 flowering and prostrate stems in the first season. In the second and subsequent years of growth, a plant can produce as many as 25 flowering stems and 40 prostrate stems, all of which grow in a loose rosette at the base of the plant. Yellow toadflax seedlings grow a taproot in 2–3 weeks. Regeneration in spring can be as early as February. The horizontal root system has adventitious buds which produce new plants. Root buds and lateral roots may begin to grow 2–9 weeks after the seed has germinated. The lateral root system of one yellow toadflax plant can produce as many as 100 shoots in the first summer. In one study, yellow toadflax increased its spread over 400 percent in one season. A patch originally covering 1 acre (0.4 ha) increased to 85 acres (34 ha) in five years. Buds on severed or broken roots will grow, and fragments as short as 0.4 in. (1 cm) can produce new plants. Root bud sprouts grow a separate root system and can become independent plants in just one year. Individual plants and roots generally live for 3–5 years, but 13-year old infestations may occur under good conditions. Impacts. Both toadflax species are short-lived, but aggressive invaders. Although one plant may do little damage to crops or to natural areas, the threat of toadflax is its potential to spread. Crop yields may be significantly reduced and native communities stressed or displaced. One study showed that a pasture plot without toadflax had 2.5 times more grass than an infested plot. Once established, toadflax outcompetes crops, pasture grasses, and native plants and becomes the dominant vegetation. The taproots and early spring growth deplete the soil of water and nutrients needed by crops, forage, or native species. Although both species contain a toxic glucoside harmful to cattle in large quantities, no poisonings have been reported because the plants are not palatable to livestock. The toxins do not affect sheep and goats. Management. Eradication of toadflaxes is difficult because of their deep, robust root systems and abundant seed production. The genetic diversity of both species complicates control. Because toadflax seedlings are poor competitors against established perennials and winter annual crops, maintenance of desirable grasses in pastures and rangeland will help prevent infestations. The plants, however, can invade even small openings in quality range. Once toadflax is established, the primary goal should be to decrease or eliminate seed production. Seeds and broken root pieces may be spread by farm machinery and outdoor recreational equipment that is not thoroughly cleaned. Livestock using infested areas should be held 6–11 days before being transported elsewhere.

426 n FORBS Seedlings are the most vulnerable to physical removal. Although small plants are fairly easily pulled, the root system of large plants provides a solid anchor. Hand-pulling plants before seeds mature, including all fragments of roots, every season for 5–6 years will deplete the seed bank. Mowing plants will prevent seed development, but root buds will produce new plants. Mowing for approximately 10 years, however, may deplete the seed bank. Repeated cultivation, 7–10 times annually for two years, will disrupt new plants as they sprout from broken roots. Prescribed fire is a poor choice. Although burning prevents seed production, it fails to kill either the roots or the seed bank and opens more bare ground for invasion. Grazing is not recommended because cattle avoid the plant and their hooves disturb the ground, creating more potential habitat. Toadflax cannot be controlled by chemical applications alone. Effectiveness varies due to different climates, waxy leaves, and genetic variation in the two species. Spraying is most effective when done at the flowering stage, when root reserves are lowest. Because both picloram and dicamba can have a residual effect on nontarget, broad-leaved perennials, glyphosate is the best choice. Yellow toadflax is more resistant to chemicals than is Dalmatian toadflax. Several insects, most of which attack both toadflax species, offer potential biological control. Three species were accidentally introduced to the United States on infected plants. A flower-feeding beetle (Brachypterolus pulicarius) was first identified on yellow toadflax in the 1920s in New York. Both adults and larvae feed on flower buds and pollen and can decrease seed production by 74 percent. Two seed-feeding weevils (Rhinusa antirrhini and R. neta) were discovered in Canada in the late 1950s. Adults feed on a variety of foliage parts, while larvae eat the developing seeds. R. antirrhini feeds primarily on yellow toadflax and can reduce seed production by 85–90 percent. Five species have been intentionally released, a defoliating moth in the early 1960s, the remainder in the 1990s. Larvae of the defoliating moth (Calophasia lunula) eat the foliage, weakening the plant, but the insect does not adapt to cold temperatures. Larvae of two root-boring moths (Eteobalea intermedia and E. serratella) feed on root tissue, also weakening the plant and reducing seed production. Adults of the root-galling weevil (Rhinusa linariae) feed on foliage and stems, while the larvae eat the tissue inside the root gall, depriving the roots of nutrients and water. Both adults and larvae of the stem-mining weevil (Mecinus janthinus) feed on tissues inside the stems, reducing flowering, seed production, and shoot biomass. Severe stem damage can kill the plant. No one insect, however, completely destroys toadflax, and one species cannot adapt to the wide range of climate where toadflax grows.

Selected References Butler, M. D., and L. C. Burrill. “Yellow Toadflax and Dalmatian Toadflax.” Weeds. Pacific Northwest Extension Publication 135, 1994. http://extension.oregonstate.edu/catalog/pdf/pnw/pnw135.pdf. Carpenter, Alan T., and Thomas A. Murray. “Element Stewardship Abstract, Linaria genistifolia ssp. dalmatica and Linaria vulgaris.” Global Invasive Species Team, Nature Conservancy, 1998. http:// www.invasive.org/gist/esadocs/documnts/linadal.pdf. Erskine, Jennifer A., and Mark J. Renz. “Dalmatian Toadflax.” New Mexico State University WeedFactsheet, 2005. http://weeds.nmsu.edu/downloads/dalmatian_toadflax_factsheet_11-06-05.pdf. Wilson, L. M., S. E. Sing, G. L. Piper, R. W. Hansen, R. De Clerck-Floate, D. K. MacKinnon, and C. Randall. “Biology and Biological Control of Dalmatian and Yellow Toadflax.” U.S. Department of Agriculture, Forest Service, FHTET-05-13, 2005. http://www.fs.fed.us/foresthealth/technology/ pdfs/Toadflax.pdf.

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n Yellow Starthistle Also known as: Golden starthistle, yellow cockspur, St. Barnaby’s thistle Scientific name: Centaurea solstitialis Synonyms: Leucantha solstitialis Family: Sunflower family (Asteraceae) Native Range. Mediterranean regions of southern Europe, northern Africa, and the Balkan peninsula. Also native to the desert regions of Southwest Asia, From Turkey to as far east as Pakistan. Distribution in the United States. Most of the United States, except some southeastern states, parts of New England, Alaska, and Hawai’i. Especially invasive in western states, and still expanding its range. Description. Yellow starthistle is usually an herbaceous winter annual, but can be biennial in mild climates. Plant morphology is variable. Young plants first grow as rosettes, where leaves are 2–6 in. (5–15 cm) long, with deep lobes reaching to the midrib of the leaf. As the plant matures, several stiff flowering stems emerge from the basal rosette, generally growing to 3.3 ft. (1 m) but sometimes as tall as 6.5 ft. (2 m). The basal leaves wither and die as flowering stems grow. Stem leaves are short and linear, 0.5–1 in. (1.2–2.5 cm) long. They may be smooth, toothed, or with wavy margins. Stem leaves are opposite and appear gray-green or blue-green due to a dense covering of fine white hairs or cottony wool. Leaf bases of the lower leaves extend down the stems, making them look winged. Plants have a long taproot, normally 3.3 ft. (1 m) but occasionally as deep as 6 ft. (1.8 m). Flowering occurs all summer, until plants are killed by frost. The 0.5 in. (1.25 cm) flower heads support a cluster of 30–100 bright yellow tubular florets, 0.5–0.75 in. (1.3–2 cm) long, in a terminal arrangement on the ends of the branched stems. Bracts at the base of the flowers are spiny, with a stiff central spine usually 0.5–1 in. (1–2.5 cm) long, but sometimes as long as 2 in. (5 cm). The central spines are yellowish or straw-colored. Flowers require crosspollination by insects and are an important source of nectar for honey bees. Each seed head has 35–80 tiny seeds, 0.08–0.15 in. (2–4 mm) long, which mature as the yellow flowers fade in late summer. Most seeds (75–90%) are produced from flowers in the center of the flower head and disperse when dried flowers become detached. Those seeds are smallest and have slightly barbed tufts of short white hairs or bristles. Seeds from the periphery of the flower head, slightly larger and hairless, remain attached to the edges of the flower head into fall and winter. Plants dry in late summer or early fall, shedding the spines, but leaving dense, fuzzy gray hairs on the flower heads. The old stems decay slowly and remain standing. Related or Similar Species. Although two species with yellow flowers resemble yellow starthistle, they have other distinguishing characteristics. Several are also listed as noxious or invasive in various states. Leaves of the Malta starthistle are covered with stiff hairs, and the spines surrounding the flower heads are slender and purplish. Grayish to tan seeds have a fine pubescence. Dried flower heads retain the spines but shed the wooly hairs. It is not known to cause chewing disease. Sicilian starthistle is not as invasive as other starthistles, and populations remain small. Rosette leaves are not as deeply lobed, and stem leaves are toothed. The central spines around the flower head are straw-colored at the top and black or dark brown at the base. Seeds are glossy dark brown with dark brown or black bristles. Both the central spines and the fuzzy gray wool are retained on the dried flower heads. Taproots of both Malta starthistle and Sicilian starthistle do not extend as deeply as those of yellow starthistle.

428 n FORBS Two species have reddishpurple or lavender flowers and spines in the center of the rosette leaves. Purple or red starthistle has purple flowers, The flower heads are surrounded by long, thick white or straw-colored spines, which remain on the bracts at the end of the season. Seeds are white and lack hairs or bristles. Flowering stems have a mound-like form as tall as 4 ft. (1.2 m). Iberian starthistle also has a mounding habit, and the lower leaves are longer, 4–8 in. (10– 20 cm) Flowers are rosylavender and white, and spines are straw-colored. It more often colonizes moist sites such as streambanks. Russian knapweed is distinguished by its purplish thistlelike but spineless flowers. This perennial has woody stems up to 3 ft. (1 m) tall, and its rhizome system is invasive. Gray hairs covering the leaves and stems give it a gray-green appearance. This species also negatively affects horses. Introduction History. Yellow Yellow starthistle is a major problem in rangeland and pasture in the western United States. (Native range adapted from USDA GRIN and starthistle was introduced to selected references. Introduced range adapted from USDA PLANTS California from Chile during Database, Invasive Plant Atlas of the United States, and selected the Gold Rush in the midreferences.) 1800s, probably as a seed contaminant in alfalfa. After 1903, starthistle was probably introduced several times in alfalfa shipped directly from Europe or from Southwest Asia. Infestations remained localized around the Sacramento River delta until alfalfa cultivation expanded between 1870 and 1905. Increased use of mechanization, such as tractors, contributed to its rapid spread in the Pacific Northwest in the 1920s. Plants invaded the grazed rangeland of the California foothills during the 1930s and 1940s. Three factors have contributed to its rapid spread since the 1960s—road building, suburban development, and more ranching. It has since spread from California to the Atlantic coast. Habitat. Yellow starthistle grows best in deep, well-drained soils under full sun, and does not do well in shady locations under trees or shrubs. It thrives in disturbed areas such as rangeland, pasture, hayfields, orchards, vineyards, and along waterways and roadsides. Although it can survive a wide range of precipitation, 10–60 in. (250–1,500 mm), yellow

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A. Several flowering stems grow from the base of the plant. (Steve Dewey, Utah State University, Bugwood.org.) B. Leaf bases appear to have “wings.” (Steve Dewey, Utah State University, Bugwood.org.) C. Rosette leaves are deeply lobed. (Steve Dewey, Utah State University, Bugwood.org.) D. The bracts are very spiny, including a long, stiff central spine. (Steve Dewey, Utah State University, Bugwood.org.) E. Flower heads grow at the ends of branches. (Charles Turner, USDA Agricultural Research Service, Bugwood.org.)

starthistle does best in climates with summer drought and is less dense in summer-rain areas east of the Rocky Mountains. Plants are found as high as 6,000 ft. (1,800 m) elevation. Reproduction and Dispersal. Yellow starthistle reproduces only by seed, 95 percent of which are viable. An average plant can produce 1,000 seeds in one season, and large plants can produce as many as 75,000 seeds. Heavy infestations can produce 50–100 million seeds per acre (125–250 million per ha). Seeds fall only 2 ft. (0.6 m) from the parent plant, and natural spread is slow because the bristles are too coarse for wind transportation. Animals and humans carry the bristled seeds short distances, trapped in fur or clothing. Human activity, such as road maintenance equipment, other vehicles, and contaminated hay and seed, is responsible for long distance dispersal. Seeds buried in the soil, as many as 2,900 per sq. ft. (29,000 per m2) are viable for 10 years, but viability of those on the surface is 3–5 years. Although most seeds germinate the year after they mature, they are capable of germination just one week after ripening. Germination is best under warm, 50–68ºF (10–20ºC), moist, conditions with plenty of light, usually in fall after the first rainfall in dry-summer climates. New plants emerge after each rainfall event. Young plants quickly establish a taproot, which enables the plant to access deeper water during the dry summer and fall. Fall seedlings overwinter as a rosette, while roots continue to grow. Impacts. Infesting 15–20 million ac. (6–8 million ha) of range and wildland in California alone, yellow starthistle is a rapid colonizer that quickly develops into dense stands, displacing native plants. Yellow starthistle is alleleopathic, exuding chemicals that prevent growth of other plants nearby. The result is a reduction in biodiversity and less forage for both native animals and livestock, which reduces rangeland values. Infestations also fragment sensitive habitat or rare plant locations. Deep taproots deplete soil moisture, damaging both annual and perennial grasslands. Water use by the plants is a serious problem in the arid western states, especially those with summer dry seasons. The spiny thickets of yellow starthistle also lower the value of recreation land. Grazing animals usually avoid areas infested with the spiny plants, putting more pressure on other parts of pasture or range. Spines may also damage the eyes of grazing animals.

430 n FORBS Yellow starthistle’s most significant impact is on horses, costing millions of dollars. Repeated ingestion by horses (over 30–60 days) causes a disease, nigropalallidal encephalomalacia, which results in a softening of a portion of the brain. It is commonly called “chewing disease” because it affects the animal’s ability to chew or swallow. The disease does not appear to affect cattle, sheep, mules, or burros. It can be a serious problem when little other forage is available or when yellow starthistle is a major contaminant in dried hay. Some horses, however, develop a taste and prefer starthistle over other feed, even when the plants are dry and spiny. The lethal dose is 5–5.7 lb. (2.3–2.6 kg) of green plants per 220 lb. (100 kg) of body weight per day. Russian knapweed is similar but more toxic. Symptoms, which can result from either green or dried plants, appear abruptly. The toxin affects the nervous system, triggering abnormal behavior, such as violent head tossing, lip twitches, tongue flicking, or excessive yawning. The horse may hold lips open with tongue hanging out. Mouth muscles become weak, and the horse loses the ability to chew or drink. Advanced stages include brain lesions and mouth ulcers. Unable to eat or drink, the horse loses weight and dies from starvation or dehydration, or requires euthanization. Parts of the brain die and do not regenerate. No treatment exists. Management. Because of the difficulty of removing dense infestations of these spiny plants, the best control is prevention. Inspection and removal of seeds from livestock, clothes, and vehicles is effective but labor intensive. Once plants have become established, any effective control must suppress seed production and requires more than one year of effort. After eradication or suppression of yellow starthistle, areas should be revegetated with perennial grasses or legumes. A combination of methods works best. Physical removal of the plants or the seeds can be done in several ways. Plants in small infestations may be pulled, but even immature flower heads must be disposed of carefully because they might produce seeds. All of the stems must be removed because even a 2 in. (5 cm) piece of stem attached to a root may regrow. Grazing or mowing reduces biomass and limits seed production, but timing of those activities is critical. Grazing or mowing at the wrong time may stimulate bolting to flowering stage. Mowing before seed sets, as long as all stem tips and leaves are removed, may be effective, but mowing too early will cause plants to resprout. Mowing or grazing too late may increase seed dispersal as seeds become trapped in equipment or animal fur. Sheep, goats, and cattle will graze the plants in early spring before the spines develop, and goats will also feed on spiny plants. Livestock may also eat the more desirable plants, thus removing competition. Burning for three successive years is effective and best done when the flowers appear. Yellow starthistle plants will still be green, but associated grasses in dry-summer climates will be dry enough to carry the fire. Fire does not affect the soil seed bank, but it reduces thatch and returns nutrients to the soil. Repeated tillage may be effective along roadsides, but in pasture or rangeland, it disturbs and exposes more soil to invasion. Application of systemic herbicides in winter when yellow starthistle plants are in the rosette stage of growth is an effective means of chemical control. Clopyralid controls yellow starthistle for one season, while picloram has more soil residual and suppresses growth for 2–3 years. Although clopyralid does not harm grasses, it can damage some nontarget species in the sunflower and legume families. Nonselective herbicides, such as glyphosate, are useful for spot treatment on bolted plants. Eliminating or reducing the number of plants encourages growth of native annuals. Biological control may be accomplished by insects, which damage the seed head and decrease the number of seeds. Six insects, three weevils, and three flies now have established populations in North America. Larvae of the seed-head weevil (Bangasternus orientalis), hairy

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weevil (Eustenopus villosus), flower weevil (Larinus curtus), seed-head fly (Urophora sirunaseva), peacock fly (Chaetorellia australis), and false peacock fly (Chaetorellia succinea) attack yellow starthistle flowers where the larvae feed on seed heads. The most successful agents in California are the hairy weevil and the false peacock fly, which reduce seed production by 43–76 percent. The Mediterranean rust fungus (Puccinia juncea var. solstitialis), which attacks foliage and young plants, was introduced into California in 2003, but effects are not yet conclusive. Tests showed that native plants were not susceptible to Mediterranean rust. Other fungi are also being tested.

Selected References “Centaurea Genus Part 2.” Plant Pest and Health Prevention Services (PHHPS), California Department of Food and Agriculture, n.d. http://www.cdfa.ca.gov/phpps/ipc/weedinfo/centaurea2.htm. DiTomaso, Joe. “Element Stewardship Abstract, Centaurea solstitialis L.” Global Invasive Species Team, Nature Conservancy, 2001. http://www.invasive.org/weedcd/pdfs/tncweeds/centsol.pdf. Murphy, Alicia. “Yellow Starthistle.” Weeds Gone Wild: Alien Invasive Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2009. http://www.nps.gov/plants/alien/ fact/ceso1.htm. “Yellow Starthistle.” Plumas-Sierra Noxious WEEDS Management Group. California Department of Food and Agriculture, n.d. www.cdfa.ca.gov/wma.

n Graminoids n Asiatic Sand Sedge Also known as: Japanese sedge Scientific name: Carex kobomugi Synonyms: None Family: Sedge (Cyperaceae) Native Range. Coastal northeastern Asia, China, Korea, southern Japan, and Taiwan. Distribution in the United States. Atlantic coastal regions from Massachusetts and Rhode Island south to North Carolina, and in Oregon. Description. Asiatic sand sedge is a perennial sedge growing 4–12 in. (10–30 cm) tall. Characteristic of the sedge family, the stems are solid and triangular in cross-section. The yellow-green, slightly arching leaves, about 0.1–0.25 in. (3–6 mm) wide, are coarse and somewhat stiff. Small marginal teeth, which can be seen with a 10x hand lens, give the leaves a rough texture. The stem base is covered with brown scales. Older basal leaves are slightly wider, darker green, and leathery. Leaf color becomes more yellow and brown in spring and fall. The extensive rhizome system, extending many feet horizontally but just below the surface of the sand, enables the plant to form extensive colonies. New shoots arise from the rhizomes, which may be 0.25 in. (6 mm) in diameter and interconnected in the stand. The tips of rhizomes are sharply pointed and can puncture skin. Long roots can extend several feet deep into the sand. Plants can be difficult to distinguish among other vegetation, but are more apparent when flowering in spring, April through June. Asiatic sand sedge is paradioecious, which is slightly different from dioecious. While male and female flowers occur on different plants, either gender may develop on any plant, even on separate stems that are part of the same rhizome system. The inflorescence, about 2 in. (5 cm) long, is a dense spike at the end of the flower stalk, which is usually shorter than the leaves. Male flowers can be identified by white strands of pollen. Female flowers have a seedhead, which is a triangular set of spikes and brown scales. Each female flower is enclosed in a dark-brown, papery sac called a perigynium, which develops a triangular achene, or hard fruit containing one seed, 0.15–0.25 in. (4–7 mm). Related or Similar Species. Two native grasses may superficially resemble Asiatic sand sedge, but because they are grasses, the stems are round in cross-section. Both American beach grass and beach panic grass, also known as bitter panicum, have leaves that are two-ranked, meaning they are on opposite sides of the stem. Their leaves also have a bluish-green cast. The inflorescence of American beach grass is much larger, 4–15 in. (10–40 cm) long. Large-headed sedge is native to coastal Russia, Japan, and western North America from Oregon north to Alaska. A newcomer to the East Coast, it has recently been found on dunes in coastal New Jersey. It can be distinguished by a more sparse growth pattern, a maximum of 4–9 shoots per sq. ft. (40–90 per m2) compared with Asiatic sand sedge with 20–50 per sq. ft. (200–500 per m2). It has longer, greener leaves, larger seedheads, and darker seeds with a sharp point that can penetrate flesh. Although the two species do not grow together in their native ranges, possible hybridization is a concern because both are wind-

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pollinated. Hybrids are usually more aggressive invaders, which could pose a new problem to coastal sand dune environments. Other sedge species (Cyperus spp.) flower in late summer to early fall. They have smooth leaves, without serrations. They also are either weakly rhizomatous or not at all. Introduction History. Asiatic sand sedge was first reported at a beach park in New Jersey in 1929. By the 1940s, it had spread to the Delmarva Peninsula. Speculation that the sedge was used as packing material for Oriental ceramics is likely just a story. Asiatic sand sedge would not make good packing material because it is not spongy for cushioning and it has sharp edges. More likely, seeds were incorporated into sand, which was used as ballast in empty ships sailing from Japan. Plants were intentionally distributed along the East Coast as early as the 1930s to bind sand dunes for erosion control. It was deliberately propagated and planted in the 1960s and 1970s. By Except for isolated sites in Oregon, Asiatic sand sedge is limited to Mid1977, the Cape May Plant Atlantic coastal regions. (Native range adapted from USDA GRIN and Materials Center in New Jersey selected references. Introduced range adapted from USDA PLANTS was distributing 20,000 plants Database, Invasive Plant Atlas of the United States, and selected references.) per year. Because of increasing realization of the plant’s invasive qualities, sales were stopped in the mid-1980s. Ironically, Asiatic sand sedge was listed as an endangered species in the 1970s. Now, it is one of the 10 most unwanted plants in New Jersey. Habitat. Asiatic sand sedge colonizes coastal beaches and sand dunes, specifically the primary dunes, the first dunes landward from the coastline, but may also be found on coastal sand pits. Storm disturbance allows Asiatic sand sedge to gain a foothold. The species tolerates salt spray and high winds, but inundation by storm surges may kill growing plants. Reproduction and Dispersal. It is not clear how Asiatic sand sedge disperses to new locations. Some populations rarely bloom and set seed, the germination rate is low, and seedlings are rare. Because plants are paradioecious, both male and female flowers may not occur in the same vicinity. Pollen, however, is easily transported over long distances by

434 n GRAMINOIDS

A. Infestations can cover the entire beach. (Louise Wootton, Georgian Court University, New Jersey.) B. New plants sprout from the extensive rhizome system. (Louise Wootton, Georgian Court University, New Jersey.) C. The stiff leaves slightly arch. (Louise Wootton, Georgian Court University, New Jersey.) D. Male flowers are distinguished by long strands of pollen. (James Burkitt, Georgian Court University, New Jersey.) E. Female flower seed heads have brown scales. (Louise Wootton, Georgian Court University, New Jersey.)

wind. Although no confirming evidence exists, seeds and plant pieces are probably saltwater tolerant and carried by currents and storm surges to new locations. Asiatic sand sedge’s major means of reproduction is vegetative, expanding its cover by its extensive rhizome system. Impacts. Large stands of Asiatic sand sedge form low dense mats, which degrade the ecosystems of the sand dunes by altering habitat for beach dwellers, displacing native plant species, reducing the biodiversity, and perhaps exposing the beach areas to more storm erosion. Asiatic sand sedge outcompetes or crowds out native dune species, such as American beach grass and sea oats, the two major sand-binding species. It also displaces, either by competition or habitat changes, several rare or threatened species, such as seabeach amaranth, seaside knotweed, sea sandwort, slender seapurslane, seabeach evening primrose, wormwood, saltmeadow cordgrass, coastal sand spurge, and sea-coast marsh elder. A study in New Jersey indicated that Asiatic sand sedge reduced the abundance of native plant species by 50–70 percent. It also affects the seaside goldenrod, which provides nectar for migrating monarch butterflies. With a lower biodiversity, the ecosystem is less resilient and more prone to disruption. By altering the beach habitat, it threatens many rare and endangered species, such as the northeastern sea beach tiger beetle, which needs open sand. Birds that may be displaced include Piping Plover, Least Tern, and Black Skimmer. Dense mats of sedge cover the open sandy areas that the birds require for nesting sites. By reducing the energy of storm waves, coastal dunes are the first line of protection against erosion and flooding. Dunes protect the ecosystems and maintain habitat for native plants and animals, as well as contribute to filtering rainwater. Although evidence is conflicting, Asiatic sand sedge may change the dune profile. One theory is that because Asiatic sand sedge is shorter than the native dune grasses, it traps less sand, resulting in lower dunes that provide less protection. The lower dune is more vulnerable to shifting, blowouts from wind, and storm surges. Other evidence indicates that the sedge stabilizes dune sand so well that dune blowouts, meaning that the dune is breached and sand is blown inland, occur less frequently. Dune blowouts are responsible for development of the bare sand habitat necessary for plovers and other high-beach species. Management. Regardless of the method used to control Asiatic sand sedge, follow-up monitoring and treatment are necessary. Early detection is critical because plants spread rapidly.

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How Bad Can It Be?

I

n a study at Island Beach State Park in New Jersey, the area occupied by Asiatic sand sedge tripled from 1985 to 2003, and doubled from 2003 to 2008. At Sandy Hook Unit of Gateway National Recreation Area in New Jersey, the situation was worse. Asiatic sand sedge increased its presence 780 percent from 1985 to 2003. From 2003 to 2008, it increased another 300 percent. As of 2008, 20 percent of the dunes in both parks were dominated by the sedge, not by native plant species. Source: Louise Wootton’s Pages, 2009.

Because the plant does stabilize the dunes, however, removal should be approached cautiously. When the infestation is eradicated or controlled, revegetating the primary dunes with American beach grass or sea oats will stabilize them and prevent recolonization by Asiatic sand sedge. Stable dunes further from the beach can be revegetated with a number of additional plants, including seaside goldenrod, beach panic grass, dune panic grass, and sea-rocket. Physical removal is limited to small plants or small infestations, usually fewer than 200 shoots. All rhizomes must be excavated from the sand without breakage, because any buried remains will sprout a new plant. Plants can be disposed of in an unsuitable habitat away from the sandy beach or covered with black plastic to bake and die. Larger stands are generally too labor intensive and costly for hand removal and should undergo chemical treatment. One or two applications of glyphosate during the growing season, preferably in summer or fall, are effective, provided they are followed by spot treatment on new shoots. Because the plant has narrow leaves that can easily be missed by a foliar spray, a colorant will be helpful to ensure coverage. No biological controls are known.

Selected References “Asiatic Sand Sedge.” Invasive Alien Plant Species of Virginia. Department of Conservation and Recreation. State of Virginia, n.d. http://www.dcr.virginia.gov/natural_heritage/documents/ fscako.pdf. “Carex kobomugi.” Invasive Plant Atlas of New England (IPANE), 2004. http://nbii-nin .ciesin.columbia.edu/ipane/icat/browse.do?specieId=121. “Carex kobomugi.” Louise Wootton’s Pages, Georgian Court University, 2009. http://gcuonline .georgian.edu/wootton/Carexkobomugi.htm. “Carex macrocephala.” Louise Wootton’s Pages, Georgian Court University, 2010. http://gcuonline .georgian.edu/wootton/carexmacrocephalanj.htm. Lea, Chris, and Greg McLaughlin. “Asiatic Sand Sedge.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2005. http://www.nps .gov/plants/alien/fact/pdf/cako1.pdf.

n Buffelgrass Also known as: African foxtail grass, anjan grass, pasto buffel, zacate buffel Scientific name: Pennisetum ciliare Synonyms: Cenchrus ciliaris, C. glaucus, Pennisetum conchroides, P. incomptum Family: Grass (Poaceae)

436 n GRAMINOIDS Native Range. Africa, Madagascar, Arabia, and Southwest Asia east to western India. Distribution in the United States. Southern states from California to Florida. Also in New York and Hawai’i. Most invasive in the deserts of California, Arizona, New Mexico, and Texas, and on the Hawaiian Islands. Description. Buffelgrass is a perennial shrubby bunch grass, usually 1.5–3.5 ft. (0.5–1 m) tall and 3–4 ft. (1–1.2 m) in diameter. It can, however, be as small as 4 in. (10 cm) or as large as 5 ft. (1.5 m) tall. The erect stems are dense, all growing from the base of the plant but branching freely at the nodes, giving it a bushy appearance. Plants form thick mats or clumps. The previous season’s growth turns gray and remains in the clump, adding to the bushy nature. Golden brown during dry periods, it quickly becomes green, growing leaves and flower spikes after even a light rainfall. The bluish-green Deliberately introduced for livestock feed and soil stabilization, buffelgrass leaf blades are flat, 3–11 in. has become invasive in desert areas in the southwestern United States. (7.5–30 cm) long, and narrow, (Native range approximated from USDA GRIN and selected references. less than 0.4 in. (1 cm) wide. Introduced range adapted from USDA PLANTS Database, Invasive Plant Plants feel rough because of Atlas of the United States, and selected references.) small soft to stiff hairs on the leaf blades. Ligules, where the leaf blade separates from the leaf sheath on the stem, are noticeably hairy. The root system is a long, dense network of stolons, usually extending 6–8 ft. (2–2.5 m) deep, but sometimes reaching 10 ft. (3 m). The inflorescences are cylindrical spikes resembling narrow bottle brushes, 0.75–5.5 in. (2–14 cm) long and 0.4–1 in. (1–2.6 cm) wide. Each spike has 30–50 long bristles, usually brown or purplish, but sometimes straw-colored. The spikelets, which have no awns, are either solitary or in clusters. The rachis is rough after the seeds drop. Fruit are bristly burs, and although the bristles are not hard or stiff, they catch on fur or clothing. Seeds cover the flower spike so densely that individual seeds are difficult to distinguish. Related or Similar Species. Buffelgrass is distinguished from similar looking native grasses by details in morphology. Arizona cottontop is sparsely branched and less shrubby.

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A. Buffelgrass clumps look bushy because all the stems emerge from the base of the plant. (Joseph M. DiTomaso, University of California–Davis, Bugwood.org.) B. Ligules are hairy. (Tom Curry, Phoenix Weedwackers.) C. The root system is dense with stolons. (Tom Curry, Phoenix Weedwackers.) D. The inflorescence is a bristly spike. (Tom Curry, Phoenix Weedwackers.)

Bush muhly is a densely branched shrub with more delicate stems. Seeds of plains bristlegrass do not densely cover the flower spike, and individual seeds can easily be distinguished. Because buffelgrass was introduced for livestock forage, many cultivars with different properties have been developed. Introduction History. Buffelgrass was deliberately introduced to Arizona for livestock feed. Trial plantings were done in Tucson by the Soil Conservation Service from 1938 to 1952. It was also used for erosion control and soil stabilization. Populations did not rapidly expand, however, until about 1980. As an example, buffelgrass was rare in Organ Pipe Cactus National Monument before 1984, but by 1994, plants occupied 20–25 sq. mi. (50–65 km2) and its range was increasing. It is still promoted in some regions as a range or hay crop. Habitat. Buffelgrass grows primarily in warm climates with frost-free winters and annual rainfall of 6–24 in. (150–610 mm), most of which occurs in summer. It is very drought tolerant and grows best in dry climates with only 7–10 in. (180–250 mm) of rain. Plants are most often found on disturbed land, such as roadsides, fields, vacant land, rangeland, or grassland, but they also invade healthy desert communities and riparian habitats. Buffelgrass also grows on rocky hillsides, usually east-facing and south-facing slopes. It is abundant on talus or scree slopes and invades less steep sites from those locations. Buffelgrass is tolerant of harsh environmental conditions, such as strong wind, aridity, erosion, and poor soils. It grows on all types of soil but is most common on sandy soils, which it prefers in its native range. Alkaline soils, with a pH of 5.5–8.2, are best. It does poorly on clay soils with little calcium, and cannot survive extended periods of freezing or flooding. Providing other conditions are met, it grows from sea level up to 6,550 ft. (2,000 m) elevation. Reproduction and Dispersal. Buffelgrass reproduces both sexually and vegetatively. Plants begin growth in late winter and flower spring through fall. Although plants have both male and female flowers, buffelgrass can produce seed either with or without fertilization. Non-fertilized seeds are identical to the parent plant. Plants produce abundant seeds, which are disseminated by wind, water, animal fur, and human clothing and footwear. Occasional floodwaters also extend its range. Most seeds germinate at the start of the wet season, usually spring, but can sprout any time it rains. Plants also sprout from the rhizomes and stolons as the root system expands. Impacts. Some of the same characteristics that make buffelgrass desirable for erosion control or livestock fodder contribute to its invasive nature. Seeds germinate rapidly, and plants

438 n GRAMINOIDS do well on poor soils. Buffelgrass is resistant to fire, drought, heavy grazing, and trampling, making it a good arid land forage. It has few pests or predators. The root system stores carbohydrate reserves, which allow it to regenerate after a fire. Buffelgrass outcompetes native species, and alters the landscape. The grass grows into dense clumps that crowd out and kill many native plants. They compete for scarce water, and the dense system of roots and branches shade the ground and prevent germination of other plants. It also may have alleleopathic compounds that prevent seeds of other plants from germinating. In Hawai’i, where it was introduced for erosion control, it is replacing the native pili grass, also known as tanglehead. In southern Texas, it threatens federally endangered species, such as Zapata bladderpod and Rio Grande ragweed, also known as South Texas ambrosia. In the Sonoran Desert of southern Arizona and adjacent Mexico, it outcompetes and excludes creosote bush, saltbush, bursage, and herbaceous grasses and forbs, replacing the complex ecosystem with a monoculture grassland, and eventually leaving it barren. Dense stands of buffelgrass increase the fuel load, resulting in fires that burn hotter. It burns readily even when green and resprouts after burning. Because fire is not an ecological part of Sonoran Desert ecosystems, fires kill most native plants. Evidence exists that after about 10 years, when it has depleted the soil of all nutrients, buffelgrass dies, leaving behind a nutrient-poor wasteland. In spite of its use for forage, buffelgrass may be detrimental to livestock. It may cause oxalate poisoning in sheep if the animals graze buffelgrass too heavily. Horses may develop a condition called “bighead,” or hyperparathyroidism, due to calcium deficiency if they eat too much buffelgrass. Management. The best control is an integrated approach and early elimination of small infestations. Because roadsides are corridors for linear spread and expansion into adjacent fields, removal in those locations should be a priority. Removal is also made more difficult if adjacent land is allowed to go unchecked, such as along the border between Mexico and Organ Pipe Cactus National Monument. Any site should be monitored for a minimum of 3–5 years. Although it is possible to remove extensive infestations, physical removal is best done only for small stands because of the labor involved. All pieces of the root must be removed or they will resprout. In Organ Pipe Cactus National Monument, buffelgrass was almost eradicated from a 25 sq. mi. (65 km2) area when volunteer labor removed over 150 tons of plant material. Follow-up the second year, which required pulling up new seedlings, was much less intensive. Repeated tilling can be effective in destroying the plant, but cannot

Sonoran Desert Weedwackers

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everal volunteer groups in southern Arizona meet monthly for buffelgrass pulls. Since 2000, when the Sonoran Desert Weedwackers was formed, approximately 120 tons of buffelgrass and nonnative fountain grasses have been dug out and removed from Tucson Mountain Park. Much of the area now supports native grasses and wildflowers. Weedwackers are also making progress in other areas, such as Phoenix Mountain Preserves, Waterman’s-Ironwood Forest National Monument, and Saguaro National Park.

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be done in a natural area. Cutting and mowing is not effective because even when plants are mowed low to the ground, buffelgrass can produce seed. Mowing may also stimulate growth, but can be used to decrease above-ground biomass prior to herbicide treatment. Continued grazing may limit root depth and weaken plants. Burning is not an option because fire damages native vegetation and buffelgrass will resprout from rhizomes. Chemical applications are effective, particularly if the standing biomass is reduced first. A combination of glyphosate and ammonium sulfate, if applied several times, will kill the root mass. Tebuthiuron and hexazinone reduce growth in some plants. Seedlings can be controlled by a variety of herbicides, including dicamba, 2,4-D, 3,6-dichlorpicolinic acid, triclopyr, tebuthiuron, or hexazinone. Picloram is not effective. Even though no biological controls, such as insects or pathogens, are yet known, it remains a controversial concept because buffelgrass is still used as forage in many areas. A leaf blight, also known as rice blast or buffelgrass blight, caused by a fungus (Pyricularia grisea) may cause significant damage, but some cultivars are resistant. Evidence suggests that the fungal blight may also harm commercial agricultural crops. Restoration of the native vegetation may help to reduce infestations. Because buffelgrass does not compete well with dense vegetation, in well-managed pastures, or in shade, planting native shrubs and trees may keep it under control.

Selected References “Buffelgrass (Pennisetum ciliare).” Citizen Scientists Combat Invasive Species. Invaders of the Sonoran Desert Region, Arizona-Sonoran Desert Museum. Tucson, AZ, n.d. http://www.desertmuseum.org/ invaders/invaders_buffelgrass.htm. IUCN SSC Invasive Species Specialist Group (ISSG). “Cenchrus ciliaris (Grass).” ISSG Global Invasive Species Database. 2006. http://www.issg.org/database/species/ecology.asp?si=846&fr=1&sts =&lang=EN. “Invasives, Sonoran Desert Weedwackers.” Arizona Native Plant Society, n.d. http://aznps.com/invasives/ weedwackers.html. Tu, Mandy. “Element Stewardship Abstract, Pennisetum ciliare.” Global Invasive Species Team, Nature Conservancy, 2002; modified 2009. http://wiki.bugwood.org/Pennisetum_ciliare.

n Cheatgrass Also known as: Downy brome, downy chess, early chess, drooping brome, wild oats, military grass, thatch bromegrass, broncograss, soft chess Scientific name: Bromus tectorum Synonyms: Anisantha tectorum Family: Grass (Poaceae) Native Range. Southern Europe, northern Africa, Arabia, and Southwest Asia, as far north as Kazakhstan and southern Russia, and east to Pakistan and western China. Distribution in the United States. Every state, including Alaska and Hawai’i. It is most prominent in the grasslands and sagebrush range in the West. Description. Cheatgrass is a winter annual grass with highly variable characteristics. Three keys to identification are the drooping panicles, long awns, and color that changes from green to purple to tan in early summer as plants mature and seeds ripen. Seedlings are bright green with hairy leaf blades and sheaths. The narrow leaves, slightly twisted initially, have a prominent midrib and soft hairs. Erect culms on mature plants, 2–35 in. (5–90 cm) tall, grow in large tufts. The flat leaf blades, 1.5–6 in. (4–16 cm) long, are narrow,

440 n GRAMINOIDS light green, and covered with soft, white hairs. Ligules are glabrous. The lower sheaths are also noticeably hairy, while the upper sheaths may be glabrous. The root system is finely divided and fibrous, normally reaching 12 in. (30 cm) deep, with few main roots. Flowering stems are erect, either smooth or slightly hairy. Inflorescences, densely grouped in open panicles within the leaves, are 2–8 in. (5–20 cm) long, with several slender branches that droop or sag to one side from the top of the inflorescences. The panicle branches are pubescent, each holding 3–8 spikelets. Spikelets, with 4–8 florets each, are 0.8–2 in. (2–5 cm) long, including the awns, and also droop from the stalk. Awns are slender and straight, often longer than 1 in. (2.5 cm). Seeds are narrow, about 0.5 in. (1.3 cm) long, light and fluffy. Plants die after flowering, usually by July. Related or Similar Species. Several introduced, invasive Cheatgrass often excludes all other plants, forming a monoculture in bromes, with a variety of commrangeland in western states. (Native range adapted from USDA GRIN and on names, resemble cheatgrass. selected references. Introduced range adapted from USDA PLANTS Distinctions are in the details. Database, Invasive Plant Atlas of the United States, and selected references.) Three annuals, Japanese brome, native to southeastern Europe and Asia, soft brome, native to southern Europe and northern Africa, and bald brome, native to the Baltic region of Europe, are widespread in disturbed areas such as roadsides. Smooth brome is a rhizomatous perennial native to Eurasia that has been widely planted for forage from Texas to Alaska. No native bromes are similar to cheatgrass. Introduction History. Accidentally introduced to North America sometime before 1860 and probably many times after that, cheatgrass was first identified in 1861 in New York and Pennsylvania. It probably arrived as a seed contaminant in grain or in soil used as ballast for ships. The plant became prominent along railroad right-of-ways, its dispersal probably facilitated by straw packing material in freight transported by railroads. It had become a serious problem in crops by the 1920s and reached its present range throughout the United States by 1930. The name “cheatgrass” was coined by farmers on the Great Plains, who believed they had been cheated with impure seed when this grass sprouted in their wheat fields.

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A. In many places, cheatgrass has replaced the native shrub and grass community. (Chris Evans, River to River CWMA, Bugwood.org.) B. The open panicles droop to one side of the stem. (Steve Dewey, Utah State University, Bugwood.org.) C. The fine roots extend deep into the soil. (Leslie J. Mehrhoff, Ecology and Evolutionary Biology University of Connecticut, Bugwood.org.) D. Leaf blades and lower leaf sheaths are softly hairy. (Tom Heutte, USDA Forest Service, Bugwood.org.)

Habitat. Cheatgrass grows under a wide variety of conditions. In the western states, it is most commonly found in sagebrush, bunchgrass, and desert scrub communities, but it also spreads into pinyon, juniper, and pine forests at higher elevations. Cheatgrass is a successful invader of rangeland, roadsides, and abandoned croplands or fields. It is also common in recently burned areas and a pest in winter crops. Although more prevalent on disturbed ground, whether as major as overgrazed or cultivated or as minimal as rodent holes, cheatgrass also invades undisturbed ground when seeds settle into and sprout in natural soil cracks. Although capable of growing on almost any soil type, cheatgrass prefers coarse soil and does not do well on heavy or saline soils or dry sites. Although it occurs in many climates, with precipitation ranging from 6 to 27 in. (150– 685 mm) annually, it is most invasive in semiarid regions with 12–22 in. (300–560 mm) of precipitation. Cheatgrass does not tolerate shade and will not survive in mature, shady forests. It can be found growing to an elevation of 13,125 ft. (4,000 m). Reproduction and Dispersal. Cheatgrass reproduces only by seed, but may resprout from rhizomes if mowed or burned too soon. It is self-fertile and needs no cross-pollination. Cheatgrass produces an extensive number of seeds, as many as 300 per plant, and maintains a large soil seed bank. Seed production, however, depends on plant density and growing conditions and is less in dense stands. The smallest seed producer may be only 1 in. (2.5 cm) tall. Seeds are viable in the soil for only 2–5 years, but for as long as 11 years in a dried state, such as in hay. At maturity, the spikelets break apart to disperse the seeds. The majority of seeds fall near the parent plant. Wind, water, rodents, and ants disperse seeds a short distance away. Seeds are carried longer distances by human activity, such as on machinery, vehicles, or clothing, and in contaminated hay, grain, or straw. Dispersal is common along transportation corridors such as roads or railroads. Both domestic and wild animals and birds also transport seeds in fur, feathers, and feces. Seeds do not need to contact bare soil, and litter promotes the germination and establishment of seedlings. The germination rate is high, although dry conditions can induce dormancy in seeds, as evidenced by seeds in dried hay. Most seeds germinate in the fall, within 1 in. (2.5 cm) of the surface. Growth begins at 35–38ºF (2.0–3.5ºC) and ends when temperatures are higher than 59ºF (15ºC). Plants overwinter as a small seedling, 0.8–2 in.

442 n GRAMINOIDS (2–4 cm) tall, and grow a root system that is ready to outcompete native spring growers. The shallow root system draws surface water early in spring, preventing other seeds and plants from germinating or growing. The flower-to-seed cycle is quick. Inflorescences develop in mid-spring, flowers follow within a week, and seeds mature in mid-to-late June. By completing its life cycle early, cheatgrass avoids dry summer conditions. By depleting soil moisture early in spring, it deprives native plants of needed water. Impacts. As an annual, cheatgrass produces leaves and inflorescences in a single season and then dies in early summer. This accumulation of thatch is a major fire hazard, which changes the fire regime from approximately once every 60–100 years to once every 3– 5 years. Fire is especially detrimental to desert communities that are not fire adapted. Cheatgrass dominates over 100 million ac. (40.5 million ha) in the western states, permanently changing the ecosystems. In many places, it has totally displaced native shrubs, such as big sagebrush and antelope bitterbrush, and perennial grasses, such as bluebunch grass, western wheatgrass, Sandburg bluegrass, needle-and-thread grass, and Thurber’s needlegrass. Replacement generally takes several years, beginning with a disturbance, such as overgrazing, that allows initial invasion. Frequent fires replace the shrubs and perennial grasses with annual grasses, causing the soils to deteriorate. Eventually, the cheatgrass outcompetes the remaining annuals and becomes a monoculture. The loss in plant biodiversity affects native wildlife in several ways. Bird numbers and species diminish because of less suitable habitat. Large animals, such as elk and mule deer, no longer have native forage plants. The numbers and diversity of predators, such as coyotes, gopher snakes, and golden eagles, decline as their prey, small mammals such as ground squirrels and packrats, becomes scarce. Once the ecosystem is impoverished, cheatgrassdominated range is susceptible to other nonnative invaders, such as medusahead (see Graminoids, Medusahead). Cheatgrass is also a weed in winter wheat, alfalfa, and other crops. The estimated cost in lost yields and control for the western United States and Canada is $350–370 million each year. Depending on the density of cheatgrass infestation, wheat yields can be reduced by 40–92 percent. The long, bristly awns injure livestock and other animals, sticking in eyes, mouths, and throat if eaten when plants are dry in late spring or summer. Such injuries may prevent the animal from eating, resulting in weight loss. Management. For effective eradication, an integrated approach, which may involve fire, herbicide, and reseeding, is necessary for at least 2–3 years to create a cumulative stress on plants. Reduction of seed output is most important. Proper land management and a seed source of native plants are essential to prevent re-invasion. Once roots of native perennials reach more than 20 in. (0.5 m) deep, they can compete with cheatgrass because it uses water at shallow depths. Total eradication, however, may not be the goal in areas where cheatgrass is important early-season forage for livestock. Physical control methods should minimize soil disturbance and seed dispersal and maintain the health of native plants. Hand-pulling is only appropriate for small areas or seedlings, and all root pieces must be removed. It may take several years before the seed bank is depleted. Live plants can be tilled into the soil in spring and fall before the plants turn purple, the process repeated whenever new plants appear. Seeds deposited deeper than 3 in. (8 cm) do not sprout. Depending on the remnant native plant community and timing, livestock grazing can be effective. Mowing soon after flowering, every three weeks in spring and early summer, prevents most seed formation. Fire will kill seeds if plants are burned after they dry but before seeds are dropped. If burned or mowed too early, roots may resprout.

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Benefits of Cheatgrass?

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heatgrass is a detrimental invasive weed, but it is also an early spring forage crop. It is important forage for both livestock and wildlife when it is green in spring, especially where native bunchgrasses have been eliminated. However, it is not dependable because the season and amount of edible green foliage depends on rainfall. The Chukar Partridge, a pheasant introduced from Pakistan as a game bird, eats cheatgrass, and is currently expanding its range, following the invasion of cheatgrass.

Chemical control is difficult because native plants or crops should be preserved. The choice of herbicide depends on the remaining native vegetation or type of crop. Several choices also exist for non-crop infestations or rangeland. Atrazine and imazapic are preemergents used in late summer or early fall to prevent seeds from sprouting. Paraquat or glyphosate can be sprayed on emerging seedlings in early spring or while seeds are developing. Biological control is limited, although rabbits, mice, and migratory grasshoppers (Melanoplus sanquinipes) eat the seeds. Over 20 diseases have been reported, but research has been limited. Cheatgrass is susceptible to a heat smut (Ustilagao bulleta), which, if severe, can decrease seed yield. A pink snow mold (Fusarium nivale) is being investigated, but no conclusions have been reached. Experiments are also being conducted on phytotoxins produced by two rhizobacteria strains (Pseudomonas fluorescens and P. syringae), which inhibit germination.

Selected References “Bromus tectorum, Cheatgrass.” NatureServe Explorer. An Online Encyclopedia of Life, 2009. http:// www.natureserve.org/explorer/servlet/NatureServe?searchName-Bromus%20tectorum. Carpenter, Alan T., and Thomas A. Murray. “Element Stewardship Abstract, Bromus tectorum.” Global Invasive Species Team, Nature Conservancy, 1999. http://wiki.bugwood.org/Bromus_tectorum. “Cheatgrass.” Non-Native Plant Species of Alaska. Alaska Natural Heritage Program, Environment and Natural Resources Institute, University of Alaska, Anchorage, 2005. http://akweeds.uaa.alaska.edu/ pdfs/species_bios_pdfs/Species_bios_BRTE.pdf. “Downy Brome (Cheatgrass).” Colorado State Parks Best Management Practices Weed Profile, 2003; revised 2005. http://parks.state.co.us/SiteCollectionImages/parks/Programs/ParksResourceSteward ship/Downey%20Brome.pdf. Pokorny, Monica. “Cheatgrass (Bromus tectorum).” 2007. http://www.ipm.montana.edu/cropweeds/ Extension/.

n Cogongrass Also known as: Speargrass, cogon grass, satintail, blady grass, Japanese blood grass Scientific name: Imperata cylindrica Synonyms: Imperata cylindrica var. major, Imperata arundinaceae, Lagurus cylindricus Family: Grass (Poaceae) Native Range. The native range is not clearly known. Eastern Africa and Asia, north to Kazakhstan and east through India, China, Korea, and Southeast Asia. Also Japan, the Philippines, Indonesia, and New Guinea. Possibly native to southen Africa, northern Africa, and Mediterranean Europe.

444 n GRAMINOIDS Distribution in the United States. Primarily in the southeastern United States, from Texas east to Virginia. Also in Oregon. Description. Cogongrass is a tufted perennial grass that grows in either loose or compact bunches. Because it is so widespread geographically, it is variable in form. The bunch consists of several lance-shaped leaves rising from ground level, directly from the rhizomes. Leaves are 1–5 ft. (0.3–1.5 m) tall and 0.5–1 in. (1.3–2.5 cm) wide, with a prominent white midrib that is slightly off center. The sharply pointed leaf blades are light green, turning orangebrown as they age. Leaf margins are finely toothed and embedded with silica crystals. The upper surface of the leaf blade is hairy near the base, while the undersurface is glabrous. Where subjected to freezing temperatures in winter, leaves turn light brown. Cogongrass has an extensive system of hard, creeping rhizomes that are sharply pointed and scaly. Most occur in the Cogongrass grows in many environments but does not tolerate cold top 6 in. (15 cm) of soil, but weather. (Native range approximated from USDA GRIN and selected they can penetrate as deep as references. Introduced range adapted from USDA PLANTS Database, 4 ft. (1.2 m). Where the plant Invasive Plant Atlas of the United States, and selected references.) is firmly established, the rhizome mass can weigh 3–16 tons per acre (7.5–40 tons per ha). Flowering season is both spring and fall. Silvery, plume-like flowers grow on a manybranched cylindrical panicle, 3–11 in. (7.5–28 cm) long and 1.5 in. (4 cm) wide. The small spikelets, 0.1–0.2 in. (4–5 mm), are surrounded by several silky white hairs, which are 0.4–0.6 in. (10–15 mm) long, making the spikelet seem larger. Spikelets are crowded on the stalks, enhancing the plume-like appearance. Flowers have three bracts within the glumes, and two stamens per flower. Seeds, which develop in spring, are very small, with a plume of long white hairs. Related or Similar Species. Japanese blood grass (I. cylindrica ‘Rubra’), a cultivar called Red Baron, is distinguished by its brightly colored, blood-red leaf edges. This attractive variety, which is not on the U.S. federal noxious weed list, is frequently sold in nurseries or on the Internet for ornamental plantings. Although it is described as noninvasive, no evidence exists to support that claim. It is not known if this variety is a potential threat to natural areas, but

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A. Cogongrass grows in dense stands. (Florida Division of Plant Industry Archive, Florida Department of Agriculture and Consumer Services, Bugwood.org.) B. Rhizomes are sharply pointed. (Chris Evans, River to River CWMA, Bugwood.org.) C. The upper surfaces of leaf blades are hairy. (Chris Evans, River to River CWMA, Bugwood.org.) D. Leaf blades have a prominent white midrib. (Chris Evans, River to River CWMA, Bugwood.org.) E. Rhizome buds produce many new sprouts. (Nancy Loewenstein, Auburn University, Bugwood.org.) F. Silvery plumed flowers, with silky hairs, are showy. (John D. Byrd, Mississippi State University, Bugwood.org.)

it becomes invasive in horticultural settings. Seedlings exhibit aggressive characteristics similar to those of the green form. The plant is very cold tolerant, and the red color is more intense in colder climates. In southern regions, the plants revert to green. The variety tends to be more invasive in regions where leaves lose their red color. Red Baron rarely blooms, and no records exist of flowering or setting seed in cold climates, but the plant has the potential to produce 3,000 seeds per season. If Red Baron were to hybridize with the main variety of cogongrass (I. cylindrica var. major) that grows in the southeastern United States, the hybrid would be both cold tolerant and invasive. Brazilian satintail, native to Central and South America, may sometimes be distinguished from cogongrass by having two bracts within the glumes and one stamen per flower. These distinctions, however, are variable. The two plants hybridize and may be the same species. California satintail resembles Brazilian satintail, but is larger, with culms generally reaching 3.3–4.9 ft. (1–1.5 m) tall. California satintail is genetically distinct from the nonnative Imperata species. Introduction History. Introduction took place several times. Cogongrass was accidentally introduced when it was brought to Mobile, Alabama, in 1912 as packing material in orange crates. In 1921, the U.S. Department of Agriculture intentionally introduced the plant from the Philippines for forage. In the 1930s and 1940s, it was brought to Florida for potential forage and for soil stabilization. The finely serrated edges and silica crystals made it undesirable for forage. Cogongrass spread by illegal plantings and contamination in soil during road construction. It was also sold as an ornamental due to its hardiness and attractive leaves. It has established in the last 50 years in the southeastern United States, especially in Alabama, Mississippi, and Florida. Habitat. Cogongrass can be found in a variety of ecosystems, from open fields to the edge of standing water, including coastland, riparian, swamplands, savannas, forests, and desert dunes. It is quick to overtake disturbed sites, such as ditch banks, pastures, roadsides, mine sites, and forestry plantations. It forms a monoculture on hundreds of acres of old phosphate mines, and is also a weed on open cultivated ground, wastelands, and in parks and golf courses. Although

446 n GRAMINOIDS it prefers acidity, pH of 4.7, cogongrass grows on any soil type that has enough moisture, including fine sand to heavy clay and soils with low fertility. Cogongrass is tolerant of many adverse environmental conditions, including shade, high salinity, and drought. It normally does not tolerate cold weather, but some stands have survived temperatures of 7ºF (−14ºC). Reproduction and Dispersal. Plants may produce several thousand small, winddisseminated seeds, which may also be carried over short distances by animals. Plants are not self-fertile and must be cross pollinated to produce viable seed. Less than half of the spikelets, however, will develop seeds. Seeds have no dormancy requirement, and 90 percent of the seeds produced are viable. Seedling survival is poor, with fewer than 20 percent living to be one year old. Cogongrass spreads primarily by rhizomes. A fragment as small as 0.08 in. (2 mm) will grow. Both seeds and fragments of rhizomes are inadvertently carried long distances on equipment, including roadside mowers, and in fill dirt during road construction. Rhizomes, which can grow 5–10 ft. (1.5–3 m) per year, can be dormant for a long time before sprouting. They have numerous buds ready to sprout, and are resistant to fire and deep burial. Impacts. Cogongrass forms dense mats of thatch and leaves that native plants cannot penetrate. The sheer mass of rhizomes enables cogongrass to dominate, but the plant may also exude alleleopathic substances. Eventually, cogongrass excludes all other plants, halting succession. Monospecific grass thickets displace native plants used by animals, including mammals, birds, and insects, for forage, shelter, and host plants. Ground-nesting species are especially at a disadvantage because of the dense cover of cogongrass. The grasses provide poor habitat for wildlife and poor forage for grazers, either wild or livestock. New growth, however, is not coarse and has some limited use as forage. The tall grasses shade out native species, especially short herbs. It invades and displaces longleaf pine flatwood communities. In Florida, cogongrass destroys the habitats of the rare gopher tortoise and the rare indigo snake. The biomass of thatch alters fire regimes, causing fires to be both more frequent and intense. Fires may injure or destroy native vegetation outright, or reduce their ability to flower and set seed. Fires especially impact small mammals, herpetofauna, and invertebrates that cannot move fast enough to escape. Management. The density and mass of rhizomes makes cogongrass difficult to eradicate. When used independently, methods such as burning, cultivation, cover crops, and herbicides have only limited success. An integrated management system, which includes mechanical, cultural, and chemical means, is necessary to eradicate or control cogongrass. The goal is to eliminate all rhizomes. Physical control of cogongrass can involve burning or mowing, but both actions stimulate growth from rhizomes. Plowing or disking, at least 6 in. (15 cm) deep, several times during a dry season will cause rhizomes to become desiccated and lose their carbohydrate reserves. This method may keep cultivated fields free of cogongrass. Mowing, burning, or fertilization, however, also stimulates seedhead formation. Mowing the grass in late spring will remove thatch and old leaves, but the area should be deeply plowed or disked 6–8 weeks later, when grass has resprouted to 6–12 in. (15–30 cm) high. Regrowth in delicate ecosystems should be followed with application of a systemic herbicide, preferably in early fall before the first frost. While hundreds of possibilities have been tested, only a few herbicides provide effective chemical control. Soil sterilants are effective, but kill everything for 6–12 months, exposing bare ground to potential erosion. If the area is to be planted to prevent erosion, bahia grass or bermuda grass provides good control in nonnatural areas. Choice of plants in natural areas is more difficult and depends on the ecosystem. Glyphosate or imazapyr applied to growing plants will reduce infestations, but several applications may be necessary. Because it leaves no soil residual, glyphosate should be used if the area will be replanted soon. If revegetation of

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Cogongrass in the World

O

ne of the world’s 10 worst weeds, cogongrass is invasive in tropical and subtropical regions throughout the world that receive 30–200 in. (750–5,000 mm) annual rainfall. It grows best with daytime temperatures of 84ºF (29ºC) and nights of 73ºF (23ºC), temperatures that are typical for the wet tropics. It is a pest in 73 countries and 35 crops, including teak, cocoa, kola, coffee, cashew, oil palm, coconut, and rubber. Annual yields may be reduced by 80–100 percent, especially significant where farmers are dependent on subsistence agriculture. Found from sea level to 6,550 ft. (2,000 m) elevation, cogongrass infests approximately 500 million ac. (20.25 million ha) of plantation and agricultural land worldwide. It thrives in disturbed sites, such as burned, overgrazed, or intensely cultivated land, and invades abandoned shifting agricultural land. Benefits of cogongrass are limited. It is used locally for thatch, forage, erosion control, paper making, and bedding for livestock.

the area is not planned, imazapyr is a better choice. Fluazifop, which is selective to grasses, is moderately effective. Sites should be monitored and spot treated as necessary. The search for natural pests for biological control of cogongrass has met with limited success. The gall midge (Orseolia javanica) is host-specific but still has limited effectiveness. Its larvae enters the plant and penetrates the shoot apical meristem, forming a gall where it develops and pupates. Few eggs survive, however, due to predation by the midge’s many natural enemies. A nematode (Heterodera sinensis), a mite (Aceria imperata), and two unidentified stem borers may have potential. A host-specific fungus (Colletotrichum caudatum), which was tested in Malaysia, did some damage, but failed to kill whole plants. Some pathogens are possibilities, but none provide effective control.

Selected References “Cogongrass, Imperata cylindrica.” Excerpted from Invasive Species Management Plans for Florida, Circular 1529, by G. MacDonald et al. IFAS Extension, University of Florida, 2009. http:// plants.ifas.ufl.edu/node/199. Johnson, Eric R. R. L., and Donn G. Shilling. “Cogon Grass.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2009. http://www.nps .gov/plants/alien/fact/imcy1.htm. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Imperata cylindrica (Grass).” ISSG Global Invasive Species Database. 2009. http:// www.issg.org/database/species/ecology.asp?fr=1&si=16. Van Loan, A. N., J. R. Meeker, and M. C. Minno. “Cogon Grass.” In Biological Control of Invasive Plants in the Eastern United States, by R. Van Driesche et al. U.S. Department of Agriculture, Forest Service Publication FHTET-2002-04, Morgantown, WV, 2002. http://www.invasive.org/eastern/biocontrol/ 28CogonGrass.html.

n Common Reed Also known as: Giant reed, phragmites, giant reedgrass, Roseau, Roseau cane, yellow cane, cane Scientific name: Phragmites australis ssp. australis Synonyms: Phragmites communis, P. communis var. berlandieri, P. phragmites Family: Grass (Poaceae)

448 n GRAMINOIDS Native Range. Because common reed is widespread throughout the world, its native origin is not clear. It is believed to have originated in Eurasia. The subspecies americanus is native to contiguous United States and Canada. Believed to be native to Puerto Rico. Distribution in the United States. Every state except Alaska. It is a problem primarily from the Great Lakes states to the East Coast and south to Georgia, and in Colorado. Description. Common reed is a warm-season, sod-forming, perennial grass that forms large clones. The erect culms, which are rigid, smooth, and hollow, are almost 1 in. (2.5 cm) in diameter and usually 6–13 ft. (2–4 m) tall. Lance-shaped leaves, 10–20 in. (25–50 cm) long, and 0.4–2 in. (1–5 cm) wide, do not grow from the base of the plant but are alternate on the culms. The leafy stems do not branch. Shoots and leaves are stiff and sharp because of high cellulose and Common reed, genetically distinctive from the native subspecies, was silica content, and leaf margins inadvertently dispersed along transportation corridors. (Native range can be somewhat rough. approximated from USDA GRIN and selected references. Introduced Leaves are deciduous in winter. range adapted from USDA PLANTS Database, Invasive Plant Atlas of the While the roots grow to about United States, and selected references.) 3.3 ft. (1 m) deep, the depth of the dense rhizome system depends on soil conditions. Rhizomes may be anywhere from 4 in. (10 cm) to 6.5 ft. (2 m) deep. They are thick and scaly and can extend 70 ft. (20 m) away from the parent plant. In soil, they are long, thick, and unbranched. In water, rhizomes are shorter, more slender, and branching. During times of low water, plants may grow stolons at the surface up to 43 ft. (13 m) long. From July through September, purple or golden flowers appear at the tips of the tall stems. The inflorescence is 1–1.25 ft. (0.3–0.4 m) long, consisting of a bushy panicle with many feathery branches or spikelets. Each spikelet, which has many silky hairs, has 3–7 florets, each 0.5 in. (1.25 cm) long, with the larger florets at the base of the panicle. Lower florets are male or sterile, without awns, contrasting with the awned female upper florets. The panicles have a fluffy look when seeds mature because of the hairs, giving the plume a gray sheen. Seeds are small, less than 0.1 in. (2.5 mm) long.

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A. Plants can be more than 10 ft. (3 m) tall. (James H. Miller, USDA Forest Service, Bugwood.org.) B. Leaves are alternate on the smooth stems. (Steve Dewey, Utah State University, Bugwood.org.) C. Stiff leaves are as wide as 2 in. (5 cm). (Richard Old, XID Services, Inc., Bugwood.org.) D. The inflorescence is a long, bushy panicle. (Richard Old, XID Services, Inc., Bugwood.org.)

Clones of common reed can live more than 1,000 years, but individual portions live only about eight years. Related or Similar Species. The species Phragmites australis is complex. Of the 27 genetic strains of Phragmites worldwide, 11 are native to the United States. Although all strains are variable, making identification difficult, the introduced invasive plant appears to be a distinctive genetic type. The native common reed, P. australis ssp. americanus, and the introduced common reed, P. australis ssp. australis, are different genotypes that can be distinguished by details. Leaf sheaths on native plants loosely adhere to the stems and drop off as the plant dies. Leaf sheaths on introduced plants are tight to the stem and are not shed. Ligules on the native variety are slightly longer than those on the introduced common reed. The glumes are also longer. No evidence exists for natural hybrids between the native and introduced forms. The native subspecies of common reed is often found intermixed with other plants, such as bulrush, cattail, arrowhead, northern redgrass, and sedge (Carex spp.), in undisturbed freshwater marshes. Introduced plants most frequently form a monoculture in disturbed or undisturbed brackish water along the Atlantic coast or along roadsides. A third subspecies (Phragmites australis ssp. berlandieri), growing in the southern states from Florida to California, is possibly a Gulf coast native. It is not easily distinguished, and its status remains unresolved. The closest relative of Phragmites australis is giant reed (Arundo donax), another invasive large grass (see Graminoids, Giant Reed). Introduction History. The aggressive genotype of common reed is grown commercially in Europe for thatch, fodder, and cellulous production. It was accidentally introduced to the United States in the late 1700s or early 1800s, probably at several Atlantic ports in ship ballast. Not noticed at first because of its similarity to native Phragmites, it became established on the Atlantic coast and spread west in the 1900s along roads, railroads, and waterways. In addition to genetic differences from native Phragmites, the fact that wildlife fail to use the invasive species and that no herbivores specialize in consuming it is further evidence that the plant was introduced. Common reed is still sold in nurseries. Habitat. As its wide geographic distribution suggests, common reed has broad environmental tolerances. It is found in climate zones ranging from desert to continental to subtropical, wherever moisture is available. It grows from sea level to 7,000 ft. (2,100 m) elevation. Leaves and stems are killed by the first frost in autumn, but stems remain erect

450 n GRAMINOIDS all winter. It prefers sunny wetlands that may be either fresh or brackish, but high salinity limits growth. In shady locations, plants will be short and stems less stiff. It has no specific soil requirements and grows in soils with a variety of nutrient levels, organic matter, acidity, and texture. It may even grow as a floating mat, not rooted in soil. Although also found in undisturbed sites, common reed more easily outcompetes native plants in areas undergoing some type of environmental stress, such as altered hydrology, dredging, restricted tidal flooding, storm drainage, and road salt or water pollution. It can be found growing in tidal or nontidal marshes, river edges, lake and pond shores, springs, irrigation ditches and other waterways, and in disturbed areas, such as roadsides and reclaimed strip mines. It does best in slow or stagnant water with silty bottoms. Reproduction and Dispersal. Common reed reproduces both by seed and vegetatively. Plants are wind-pollinated, self-fertile, and can also produce seeds without fertilization. Each plant produces thousands of seeds each year. Viability of seeds is affected by site or environmental factors, and dispersal is by wind and water. Seeds germinate in spring, under alternating night and day temperatures of 60ºF (15.5ºC) to 85ºF (29.5ºC). They need exposed moist soils, and seedlings cannot emerge from depths below 2 in. (5 cm). A seed bank in marshy soils may re-infest sites after eradication. Dispersal to new sites is often accomplished by seeds, even though mortality rate of seedlings is high, due to flooding, drought, salt, or freezing. Rhizome fragments carried along waterways and shorelines grow into new plants, giving rise to new stands. Rhizome pieces caught in machinery are responsible for spreading the plant along roadsides. Sprouts from rhizomes are less sensitive to environmental conditions. Each rhizome lives for 2–3 years. Impacts. The nonnative aggressive strain of Phragmites has invaded native Phragmites habitat and displaced it on the East Coast, where most stands are now the introduced European genetic strain. The native genotype is still common in the Southwest and Pacific Northwest except along roads and waterways and in urban areas. Common reed changes hydrology, alters wildlife habitat, and increases the fire potential because of the high biomass. While the native common reed is valuable to waterfowl, such as ducks, herons, and egrets, and provides cover for deer, the introduced plant crowds out native plants and reduces biodiversity. It degrades the quality of wetland habitat, especially for migrating waterfowl, and provides little food or shelter for wildlife. Some rare and threatened bird species in Connecticut that are present in native, short-grass marshland habitats are absent from Phragmites monocultures. Limited research indicates that bird diversity rebounds after control or eradication. Common reed forms dense, impenetrable stands of both living and dead stems, as many as 20 per sq. ft. (200 per m2). The nonnative variety sprouts earlier in spring than the native Phragmites, producing a greater biomass sooner. Plants grow quickly, and colonies can cover hundreds of acres. Stems can grow 1.5 in. (3.8 cm) in one day, and rhizome runners can grow more than 10 ft. (3 m) in one growing season. The rapid growth rate of rhizomes and shoots starves competing native plants of nutrients. The dense growth blocks light, and the root system occupies all the soil space beneath the surface. Management. Any attempts to control common reed must involve a long-term plan because colonies are long-lived. Infestation of new water bodies can be prevented if all equipment on boats and trailers is thoroughly inspected when leaving and entering a water area. Deliberate planting for erosion control or ornamental purposes also should be avoided. Physical elimination may include several years of cutting, pulling, or mowing. Prescribed burns after flowering will reduce dead biomass, both standing and ground litter, and decrease the hazard of wildfire. Reduction in biomass may also allow other plants to sprout

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the following spring. Burning in spring and summer before plants flower, however, may stimulate growth because rhizomes are not affected by fire. Repeated mowing slows the spread of common reed by depriving it of its photosynthesis ability but will not kill the plants. The increase in temperature under a cover of plastic, however, may kill rhizomes. Sediments may be excavated to remove the rhizomes, but any pieces left in the soil will regenerate. Because common reed will die if water is too salty, manipulation of tidal flow may increase salinity above its tolerance levels. Foliar application of glyphosate is the most effective chemical treatment. Applications work better when done before the rhizome network becomes established. Best applied in late summer or early fall after flowering, the herbicide can be either sprayed onto foliage or painted on cut stem bases. Treatments are necessary for several years to kill regrowth from rhizomes. No biological control for common reed is available in the United States, but research is being conducted on several nonnative insects. Larvae of three shoot flies (Lipara spp.) produce galls, which prevent the formation of inflorescences. A gall midge (Lasioptera hungarica), a legless red mealybug (Chaetococcus phragmitis), a shoot-boring moth (Archanara geminipuncta), and a fly (Platycephala planifrons) all weaken stem tissue. Four moths (Rhizedra lutosa, Phragmataecia castaneae, Chilo phragmitella, and Schoenobius gigantella) feed on roots and rhizomes. Although none of these insects have been deliberately introduced to North America, some are found in the United States. No evaluations have yet been made on their effectiveness.

Selected References Blossey, B., M. Schwarzlander, P. Hafliger, R. Casagrande, and L. Tewksbury. “Common Reed.” In Biological Control of Invasive Plants in the Eastern United States, by R. Van Driesche et al. U.S. Department of Agriculture, Forest Service Publication FHTET-2002-04, 2002. http:// www.invasive.org/eastern/biocontrol/9CommonReed.html. “Common/Giant Reed.” Aquatic Invasive Species. Indiana Department of Natural Resources, 2005. http://www.in.gov/dnr/files/PHRAGMITES2.pdf. Gucker, Corey L. “Phragmites australis.” In Fire Effects Information System, U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, 2008. http://www.fs.fed.us/database/feis/. Saltonstall, Kristin. “Common Reed.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2009. http://www.nps.gov/plants/alien/fact/ phau1.htm.

History of Common Reed

C

ommon reed has been part of the native flora in the southwestern United States for at least 40,000 years, as indicated by remains found in ground sloth dung. Preserved remains have also been found in coastal salt marsh sediments dated 3,000–4,000 years ago. Native Americans used common reed for arrow shafts, ceremonial objects, musical instruments, and cigarettes. Leaves and stems were used by the Anasazi in southwestern Colorado about 1,000 years ago for construction of mats.

452 n GRAMINOIDS

n Cordgrasses and Their Hybrids Also known as: Smooth cordgrass, Atlantic cordgrass (Spartina alterniflora); dense-flowered cordgrass (Spartina densiflora); salt meadow cordgrass, salt marsh hay (Spartina patens); common cordgrass (Spartina anglica); smooth cordgrass hybrid (Spartina alterniflora x foliosa) Synonyms for smooth cordgrass: Spartina alterniflora var. glabra, S. alterniflora var. pilosa Synonyms for salt meadow cordgrass: Spartina patens var. juncea, S. patens var. monogyna Synonym for common cordgrass: Spartina maritima x alterniflora Family: Grass (Poaceae) Native Range. Smooth cordgrass and salt meadow cordgrass are native to the Atlantic and Gulf coasts, from Texas to Newfoundland. Smooth cordgrass is also native to the east coat of South America and the islands of Trinidad and Guadeloupe in the Lesser Antilles, but not to Central America. Salt meadow cordgrass is also native to many Caribbean Islands in both the Greater and Lesser Antilles. Dense-flowered cordgrass is native to southern South America, including Brazil, Uruguay, Argentina, and Chile. Common cordgrass is a hybrid beween smooth cordgrass and small cordgrass (S. maritima), which is native to England. Distribution in the United States. Distribution of alien cordgrasses in disjunct. They are found in various bays and coastal locations from Washington south to the San Francisco Bay region in California. Denseflowered cordgrass is also found in isolated parts of Texas. Description. Smooth Cordgrass: Smooth cordgrass is a perennial emergent grass that usually grows in dense stands. Although its size varies accordAlthough native to the Atlantic and Gulf coasts of North America, as well ing to conditions, its stiff, erect as to the Atlantic coast of South America, smooth cordgrass is invasive on stems, 1 in. (2.5 cm) wide at the Pacific coast. (Adapted from USGS Nonindigenous Aquatic Species the base, are often 1 ft. (0.3 m) Database and selected references.) tall in spring and may reach a

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A. Smooth cordgrass and its hybrids colonize mudflats, changing the habitat to meadow. (California Coastal Conservancy, San Francisco Estuary Invasive Spartina Project.) B. The extensive root system, with rhizomes spreading just beneath the surface, traps sediment. (California Coastal Conservancy, San Francisco Estuary Invasive Spartina Project.) C. Stems are round, and both leaves and leaf sheaths are hairless. (Joseph M. DiTomaso, University of California–Davis, Bugwood.org.) D. The inflorescence is a narrow spike. (Joseph M. DiTomaso, University of California–Davis, Bugwood.org.)

height of 6–8 ft. (1.8–2.5 m) by fall. Stems are round, spongy, and hollow, decreasing to less than 0.3 in. (8 mm) in diameter toward the top. Gray-green leaves, 8–22 in. (20–55 cm) long and 1–2 in. (2.5–5 cm) wide, are flat when fresh and sharply pointed at the tips. The green color of healthy young shoots and leaves is often streaked with red or purple just below the sediment surface. Both upper and lower leaf surfaces, as well as the leaf sheaths, are hairless, but the upper leaf surface is ribbed. Ligules are hairy. The tough, whitish rhizomes are 0.15–0.25 in. (4–7 mm) wide and fleshy. Although the rhizomes may extend deeply into the substrate, approximately 75 percent of the root system is in the top 6 in. (15 cm), and more than 40 percent grow in the upper 2 in. (5 cm) of soil. Smooth cordgrass blooms from July to November and has colorless flowers. The narrow inflorescence is a spike-like panicle, 4–18 in. (10–45 cm) long and less than 1 in. (2.5 cm) wide. It has 3–30 spikes or branches, each as long as 5 in. (12.5 cm). The branches, loosely overlapping and loosely pressed against the main axis of the inflorescence, each have 5–35 spikelets, or flowers. The glumes may be glabrous or hairy. Dense-Flowered Cordgrass: Dense-flowered cordgrass has a compact form, growing in erect, tufted clumps. The slender stems are 1–5 ft. (0.3–15 m) tall. It has grayish foliage and narrow leaf blades (approximately 0.25 in. (7 mm) wide. Leaf blades are 4.5–17 in. (12–43 cm) long and inrolled when fresh. Its rhizomes are short and stout, about 0.4 in (1 cm) wide, and the root mass is fairly shallow. Plants flower from April through July. The inflorescence is 2.5–12 in. (6–30 cm) long and less than 0.5 in. (1.3 cm) wide. Its 2–20 spikes, approximately 4 in (11 cm) long, are overlapping and closely pressed to the axis. The glumes are short with sharp bristles. Until 1984, this plant was misidentified as the native California cordgrass. Salt Meadow Cordgrass: The decumbent and matted stems of salt meadow cordgrass form a dense turf or sod. When not in bloom, it is distinguished by its thin, wiry stems which reach 1–4 ft. (0.3–1.2 m) tall and its tightly furled, or inrolled, leaf blades. Both stems and leaves are narrow at the base, less than 0.2 in. (5 mm) wide. Leaf blades are green, 4–20 in. (10–50 cm) long and very narrow, less than 3 mm wide. Plants are reddish purple at the base. The plant flowers in late summer. The inflorescence, 1–9 in. (5–22 cm) long and 0.8–4 in. (2–9 cm) wide, is an open panicle. Several spikes, usually 1–4, but as many as

454 n GRAMINOIDS 13, branch at a 60° angle from the stem axis. Each spike or branch is 0.4–3 in. (1–8 cm) long. Rhizomes are long and slender, approximately 0.2 in. (3 mm) wide. Common Cordgrass: Common cordgrass is a fertile hybrid between smooth cordgrass and small cordgrass, a species native to England. The cross, which originated in England, initially produced a sterile hybrid, Spartina x townsedii, but backcrossing produced the fertile S. anglica. Although common cordgrass may have many of the same characteristics as smooth cordgarss, its morphology is highly variable, probably due to its extensive hybridization. It spreads to cover extensive meadows with large monospecific stands. Height of the stout stems is variable, usually 1–4.3 ft. (0.3–1.3 m), but plants can be as short as 2 in. (5 cm). Ligules have a hairy fringe. Leaves may be green or grayish-green, flat or inrolled, persistent or falling. Blades are Dense-flowered cordgrass is native to southern South America. (Native 14–18 in. (35–45 cm) long and range adapted from USDA GRIN and selected references. Introduced 0.2–0.5 in. (5–12 mm) wide. range adapted from USDA PLANTS Database, Invasive Plant Atlas of the Flowering season is variable, United States, and selected references.) usually July to November, but sometimes as late as February. The inflorescence, 4.5–15.5 in. (12–40 cm) long, is an erect and dense panicle with 2–12 slightly-spreading spikes. Spikes are 5.5–8.5 in. (14–21 cm) long. Smooth Cordgrass x California Cordgrass Hybrid: Smooth cordgrass has hybridized with native California cordgrass to the extent that few to no pure smooth cordgrass stands remain in some regions. Hybridization has resulted in many different morphologies. Early hybrids are usually taller than either parent, have larger flowers, and produce more pollen. Later hybrids do not resemble either smooth cordgrass or California cordgrass, and may have spiky leaves, an odd orange color, or other variations. Later, back-crossed generations become increasingly more difficult to identify in the field on the basis of morphology. Related or Similar Species. California cordgrass, native from Bodega Bay, north of San Francisco, south to Baja California, is shorter, less than 4.5 ft. (1.4 m) tall by autumn. It usually has no red pigment when healthy, and its leaf blades are 6–18 in. (15–45 cm) long. This native

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species blooms from June to September. The inflorescence, 3.5–10 in. (9–25 cm) long, is a dense cylinder, with spikes that are closely overlapping and pressed against the main axis. The native cosmopolitan bulrush, also called saltmarsh clubrush or alkali bulrush, has grasslike leaves with reddish-purple bases. As a sedge, its stems are triangular in cross-section. The unbranched inflorescence is a short open umbel, 4–8 in. (10– 25 cm) long, with a cluster of 2–15 spikelets. Each brown flower is oval or cylindrical, 0.5–1 in. (1.3–2.5 cm) long. Sea-side arrowgrass, also a native plant, grows 8–30 in. (20–76 cm) tall with very slender stems. The plants bloom from summer to fall, and the inflorescence is an unbranched spikelike raceme, 4–16 in. (10–40 cm) tall. The six-parted green or brown flowers are showy and grow on short pedicels. Introduction History. Although the date is disputed, smooth cordgrass may have been introduced to Willapa Bay, Native to the Gulf and Atlantic coasts of North America and to the Washington, in 1894, mixed Caribbean, salt meadow cordgrass displaces native coastal grasses in with packing material for eastern Pacific coast states. (Native range adapted from USDA GRIN and selected oysters shipped into the state for references. Introduced range adapted from USDA PLANTS Database, propagation. It also may have Invasive Plant Atlas of the United States, and selected references.) arrived as ballast in ships in the early 1900s. Because the plant is important for sedimentation and stabilization in its native range, it was intentionally introduced into Puget Sound in the 1940s for shoreline stabilization and salt-marsh restoration. A small amount was planted in the Siuslaw River estuary, Oregon, in the 1970s for the same reasons, but when the plot rapidly increased to an acre in size by the 1990s, the grass was recognized as invasive and eradicated. Smooth cordgrass was also deliberately planted in San Francisco Bay in the early 1970s for stabilization and restoration. Dense-flowered cordgrass was probably inadvertently brought to Humboldt Bay in 1850 as ballast on ships carrying lumber back to Chile. It was recognized as an alien pest in the 1980s, and is the alien species which dominates the salt marshes in Humboldt Bay. Denseflowered cordgrass was introduced into Marin County, California, for a landscape restoration project, and some plants occur in San Francisco Bay.

456 n GRAMINOIDS A small patch of salt meadow cordgrass occurs at Southampton Marsh in the San Francisco Estuary. The plant is also in Siuslaw Estuary in Oregon and also on the west side of Puget Sound in Washington. Small patches of common cordgrass are visible on a 1939 aerial photo of the Siuslaw River in Oregon, and two plants were found in San Francisco Bay in 1970. Thought at the time to be the sterile hybrid, common cordgrass was introduced into Puget A hybrid originating in England, common cordgrass is invasive to Pacific Sound in the early 1960s, as forcoastal zones. (Native range adapted from USDA GRIN and selected age for cattle. It was also intenreferences. Introduced range adapted from USDA PLANTS Database, tionally taken from Puget Sound Invasive Plant Atlas of the United States, and selected references.) to San Francisco Bay in 1977. Habitat. Although each species or hybrid has a preferable habitat, cordgrasses generally grow in saline or brackish water on muddy banks, salt marshes, and beaches in the intertidal zone, where they are protected from strong wave action. Plants may tolerate as much as 12 hours a day of flooding in water with a pH of 4.5–8.5 and salinity of 10–60 ppt. It especially invades bare mudflats and sandflats in shallow estuaries, but is found on a variety of substrates, including clay, gravel, and cobble. The hybrid (S. alterniflora x foliosa) of smooth cordgrass with the native California cordgrass grows both lower and higher in the tidal zone in San Francisco Bay than does the native California cordgrass, which has a more narrowly defined range. Cordgrasses do not grow in freshwater, and are generally excluded from terrestrial sites by competition from other plants. Reproduction and Dispersal. Cordgrasses reproduce and spread both by seed and by rhizomes and root fragments. Plants may flower and set seed in their first year, but most do so after 2–3 years of growth. Due to low soil temperatures, plants may not flower and set seed in all locations where the species has been introduced. Although plants develop many inflorescences, little seed is produced because cross-pollination (by wind) is required, a rare occurrence in isolated patches or clones. Seeds ripen from October to January and, if deposited in mud, germinate from February through May. Seeds are carried by tidal action and currents and may adhere to animals and birds. No seed bank exists because seeds are viable for only one year and cannot survive desiccation. Most seedlings fail to survive winter storms, but the remainder grow quickly in spring. Erosion, waves, and currents break off pieces of established plants, which are then dispersed by currents and tides. A fragment must have roots or rhizomes in order to grow. Initial colonization consists of isolated clones, which grow outward in circular patches. Spreading quickly by growth of rhizomes, frequently more than 3.3 ft. (1 m) per year, these circular patches coalesce to become continuous meadows. From April through September, plants grow rapidly. All the flowering stems die back in cold weather and are usually washed away with tides, but young, green shoots remain all winter. Impacts. Smooth cordgrass grows fast to create monotypic, impenetrable stands, altering the habitat and negatively affecting plants, birds, and other animals. It threatens the native

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California cordgrass by producing more seeds, which also have a better germination rate, and grows 6–7 times faster. By hybridizing with California cordgrass, smooth cordgrass endangers the genetic distinction of the native species. Both smooth cordgrass and its hybrids are more vigorous than the native species. By overgrowing and shading, it displaces native pickleweed, seaside arrowgrass, fleshy jaumea, and algae. Its propensity to colonize bare mudflats converts those bare sites and channels to marshland, changing the ecosystem, which formerly provided prey-rich nurseries for juvenile chum salmon and English sole. It reduces forage habitat for shorebirds and waterfowl, both residential and migratory, including the endangered California Clapper Rail in San Francisco Bay. Smooth cordgrass thickets also alter the habitat for the endangered salt marsh harvest mouse, as well as for other animals. The loss of mudflat habitat also negatively affects Dungeness crab, clams, and other marine life, and threatens commercial oyster beds. At its worst, almost 30 percent of the mudflats in Willapa Bay, Washington, were dominated by smooth cordgrass. Smooth cordgrass stands trap sediment, which not only changes the invertebrate population, but also clogs and fills in natural and flood control channels. Flood patterns are altered, permanently changing the hydrological conditions where it invades. Most alien Spartina species present the same problems, perhaps in slightly different ecosystems. Although dense-flowered cordgrass has displaced native pickleweed, saltgrass, and seaside arrowgrass in the lower- and mid-elevation salt marshes in Humboldt Bay, it especially threatens the high-elevation marsh, which has the most biodiversity and two rare annuals, Humboldt Bay owl’s clover and Pt. Reyes bird’s beak. It has also begun to colonize tidal mud flats, where its stem and root density alters marsh habitat for rodents, birds, invertebrates, crustaceans, and gastropods. A large amount of dead matter accumulates at the upper tidal limit of the upper marsh. Management. A clonal patch of smooth cordgrass may live for more than 100 years, and given its coastal location, it is likely that plants will continue to spread along the West Coast. Many cordgrass stands grow in deep mud that is impossible to approach on foot or by boat, a complication to management strategies. Small populations, covering fewer than 5 ac. (2 ha), may be controlled by a number of physical methods. Plants rooted in mud, especially small plants or seedling, are easily extracted, but a shovel may be needed for harder substrates. Larger plants of denseflowered cordgrass may be pulled out because that species grows in clones that are more clumped, with a shallower root system. Plants that are removed should be deposited above the high-tide line, where they will dry and die. Small infestations, 3.3–33 ft. (1–10 m) in diameter, may be solarized, buried under a 100 percent shadecloth or black plastic. Mowing plants first may facilitate covering, which is best done in spring. Although plants may die within four months, it is best to keep the area covered and monitored for two years. Tarping, of course, will kill everything beneath the cover. In climates where they go dormant, plants may be mowed to mud level in late fall. In areas of year-round growth, mowing eight or more times a year may be effective in reducing shoot density and seed production. Chemical applications are preferred when digging would be too damaging to the environment. Glyphosate failed to eliminate cordgrasses, and imazapyr is now the only herbicide used for effective control. It is the most economical herbicide that is also safe for the workers and the natural environment. Spring applications are best. Significant progress has been made toward eradicating cordgrasses in both Washington and in California. Although snow geese like to eat the roots of smooth cordgrass in Florida, few biological control agents have been approved because they may also attack the native and endemic California

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Eradication Success

I

n only three years, an invasion of smooth cordgrass in Humboldt Bay, California, increased from 100 sq. ft. (9.3 m2) to almost 5,000 sq. ft. (465 m2). By isolating the area with dikes, mowing the plants, applying excess salt, and covering the area with black plastic, the California Department of Fish and Game succeeded in eradicating the stand, preserving the local mudflat ecosystem. Two years of repeatedly mowing a small experimental plot in the nearby Mad River Slough killed all the dense-flowered cordgrass plants, allowing native plants to recolonize. No seed was recruited from adjacent areas, and the area remained clear of dense-flowered cordgrass. When similar treatment was applied to a larger, 15 ac. (6 ha) area, mowing also killed the cordgrass, but seeds were carried in by waves and currents. Although young cordgrass plants were selectively torched in spring, the growth of native species complicated the eradication efforts. This experiment indicated that eradication efforts must have a regional approach to avoid seed recruitment from elsewhere. (Humboldt Bay National Wildlife Refuge Complex, 2010.)

cordgrass. A planthopper (Prokeleisa marginata), which successfully stunts or kills smooth cordgrass in greenhouse experiments, has been approved for release into Willapa Bay in Washington State. Smooth cordgrass in other locations, however, proved to be tolerant of the planthopper. The marsh periwinkle (Littoraria irrorata), native to the Atlantic and Gulf coasts, is a sea snail that grazes on and causes a fungus to develop, which weakens but does not kill plants.

Selected References Daehler, Chris. “Spartina alterniflora.” In Invasive Plants of California’s Wildlands, edited by Carla C. Bossard, John M. Randall, and Marc C. Hoshovsky. Berkeley: University of California Press, 2000. http://www .cal-ipc.org/ip/management/ipcw/pages/detailreport.cfm@usernumber=75&surveynumber=182.php. Howard, V. “Spartina alterniflora.” U.S. Geological Survey Nonindigenous Aquatic Species Database, Gainesville, FL, 2010. http://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=1125. “Invasive Spartina in Humboldt County.” Humboldt Bay National Wildlife Refuge Complex, 2010. http://www.fws.gov/humboldtbay/spartina.html. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Spartina alterniflora (Grass).” ISSG Global Invasive Species Database, 2005. http:// www.issg.org/database/species/ecology.asp?si=792. San Francisco Estuary Invasive Spartina Project. Coastal Conservancy. n.d. http://www.spartina.org/ species.htm.

n Crimson Fountain Grass Also known as: African fountain grass, crimson fountain grass, tender fountain grass Scientific name: Pennisetum setaceum Synonyms: Pennisetum ruppelii, P. macrostachyon, P. rueppelianum, Phalaris setaceum, Cenchrus setaceus Family: Grass (Poaceae) Native Range. North Africa, from Morocco east to Egiypt and south to the Sudan and Ethiopia. Also on the Arabian Peninsula. Possibly native to eastern Africa as far south as Zimbabwe.

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Distribution in the United States. From Oregon and California on the West Coast, east to Colorado and Texas, and in the southern states of Arkansas, Louisiana, Kentucky, Tennessee, and Florida. Also in Hawai’i. Description. Fountain grass is a coarse perennial grass that forms dense clumps of erect stems as tall as 1.5–5 ft. (.5– 1.5 m). The rigid leaf blades are 8–26 in. (20–65 cm) long and only 0.08–0.14 in. (2– 3.5 mm) wide. Leaf sheaths are 1.5–3 in. (4–8 cm) long, and either smooth or hairy. The leaf color depends on water availability. It is greener with more water, but changes to purplish and then tan as plants dry. Leaf margins often have white hairs. The fibrous root system extends as deep as 12 in. (30 cm) into the soil, and has no rhizomes. Depending on climatic region, crimson fountain grass may have a long flowering season, from January to November. Inflorescences are a long panicle-like spike, with small, densely grouped pink or purple Crimson fountain grass continues to spread throughout the Southwest, flowers and many bristles. The displacing desert scrub. (Native range approximated from USDA GRIN prominent, feathery flowerheads, and selected references. Introduced range adapted from USDA PLANTS 3–15 in. (7.5–38 cm) long, Database, Invasive Plant Atlas of the United States, and selected references.) resemble bottlebrushes. Spikelets are usually 0.18–0.27 in. (4.5–7 mm) long and very narrow. Of the two florets on each spikelet, the lower is usually sterile. The many short, slender bristles remain on the spikelet when it detaches from the rachis. Seeds are yellowish brown and smooth. Related or Similar Species. Several Pennisetum species, introduced primarily as ornamental garden plants, have become invasive. Most are tall plants with showy panicles. They often have more than one common name and may be difficult to distinguish. Missiongrass, also called feathery pennisetum, is native to tropical Africa and India. It is now distributed on many Pacific islands, including Hawai’i, as well as in Florida and Puerto Rico. It is a tufted annual or perennial with few simple or branched culms 1.6–10 ft. (0.5–3 m) tall. The narrow leaf blades are 2–17.5 in. (5–45 cm) long, either smooth or hairy. The inflorescences are dense yellow-brown spikes, 2–10 in. (5–25 cm) long. Spikelets, with two florets on each, are purplish or yellow brown and surrounded by many bristles. It is sometimes confused with kyasuma grass or with elephant grass. Missiongrass predominantly invades dry

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A. Plants are often used as attractive ornamentals. B. Leaf sheaths and leaf margins may be hairy. C. The inflorescence is a showy plume. (Joseph M. DiTomaso, University of California–Davis, Bugwood.org.)

rangeland, grasslands, and disturbed sites. Adapted to low fertility and sandy soils, it grows quickly and is somewhat shade tolerant. It has been deliberately introduced as a pasture grass in some areas and also spreads by vehicles. It outcompetes native species, preventing regeneration of native trees and shrubs. Its dense tussocks alter the normal fire regime, and it spreads quickly after a fire. It can also reproduce from cuttings. Management is similar to fountain grass. Feathertop, a showy tufted perennial grass native to northeastern Africa, is scattered in several states, including California, Texas, Colorado, Michigan, Georgia, and Hawai’i. It is distinguished by the presence of rhizomes and its white flowers. Growing to 2.6 ft. (0.8 m) tall, it invades disturbed sites such as roadsides. Leaf blades are 2–15.5 in. (5–40 cm) long, and sheaths are either glabrous or slightly hairy. Rhizomes are short, wiry, and branched, reaching a depth of about 8 in. (20 cm). The dense fibrous root system may be 24 in. (60 cm) deep. Greenish-white to straw-colored flowers grow on short, spike-like, panicles, 1.5–4 in. (4–10 cm) long. The many bristles are straw color or white and can be 2 in. (5 cm) long, while the lower parts appear feathery. Seeds are yellowish brown, often with a purple tinge. This species tolerates saline conditions and frequent mowing, and recovers after a fire. Because it also invades coastal scrub, it has the potential to become noxious. Elephant grass is an annual or perennial grass found in California, Texas, Florida, Hawai’i, Puerto Rico, and the Virgin Islands, where it invades forests, grassland, riparian sites, and coastal beaches. This stout plant has a vigorous root system of creeping rhizomes 6–10 in. (15–25 cm) long. Leaf blades, 1–3 ft. (.3–.9 m) long and 0.4–1.2 in. (1–3 cm) wide, terminate in a fine point. The smooth culms, 6.5–16.5 ft. (2–5 m) tall, branch toward the top. Yellow-brown inflorescences are compact, with bristly spikes 3–12 in. (8–30 cm) long. Spikelets, with two florets each, are surrounded by several short bristles, and one bristle as long as 1.5 in. (4 cm). Elephant grass grows in a wide range of habitats but is tallest in moist, rich soils where it can create dense reedy thickets to 10 ft. (3 m) tall. Seeds are rarely produced. This species reproduces primarily vegetatively and resprouts vigorously when cut. Like other Pennisetum species, it displaces native plants. Digging out the plants is an ineffective method of control because of the extensive rhizome system. It is best to treat it with a herbicide. African feathergrass occurs in California, Texas, and Hawai’i. A tussock-forming perennial grass that reaches 3.2–6.5 ft. (1–2 m) tall, it resembles pampas grass (see Graminoids, Jubata Grass and Pampas Grass), but is native to southern Africa. Leaf blades, which grow from both the base of the plant and from the stems, are either light or dark green, sometimes with bluish-purple edges. They reach 4 ft. (1.2 m) in length, have pronounced ribbing on

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the upper surfaces, and are slightly curved rather than flat in cross-section. They have serrated edges and hairy sheaths. The root system is extensive. Stout rhizomes can be 6.5 ft. (2 m) long, and both rhizomes and fibrous roots extend 3.2 ft. (1 m) deep into the soil. Inflorescences are 3–12 in. (7.5–30 cm) long, with prominent bristles, about 0.4 in. (1 cm) long. Yellow-brown seeds mature in late summer and fall and are dispersed by tiny barbed hairs that catch in fur and clothing. Like many other feathergrasses, it was imported for use as an ornamental, often for garden ponds, and now invades disturbed areas and roadsides. African feathergrass prefers damp riparian habitats in full sun, where its unchecked growth can block waterways. Young plants need moisture, but become drought tolerant as they mature. Dry plants pose a fire hazard. It reproduces both by rhizomes and abundant seed production, spreading quickly and crowding out native species. Physical control is made worse by the difficulty of digging out the extensive root system. Kyasuma grass, currently found in Florida, is native to northern tropical Africa and India. It is a summer annual that propagates solely by seed and grows to 3.2 ft. (1 m) tall. Leaf blades, 6–10 in. (15–25 cm) long, are flat and glabrous. Culms are freely branching, both from the base and higher on the stem. The attractive pinkish-brown flowerheads grow on a panicle-like spike, 2–6 in. (5–15 cm) long. Many bristles, each 0.2–0.4 in. (5–10 mm) long, surround the spikelets, giving it a wooly look, but one bristle is conspicuously longer, 0.6–1 in. (16–24 mm). Although kyasuma grass is useful for soil stabilization and provides good forage, hay, and silage because it can be cut several times a year, it can become an invasive plant in disturbed sites, roadsides, fallow fields, or cultivated crops. Several cultivars of fountain grass have been developed, with green, reddish, or purple foliage. Although cultivars are supposedly sterile, some do set seed and may become a problem. Introduction History. Crimson fountain grass has been introduced to both Hawai’i and mainland United States several times as an attractive ornamental grass in landscape plantings. The first records of the plant are dated 1914 in Hawai’i and 1917 in California. It has now become naturalized in the southwestern states and is spreading in southern California and in the deserts of the southwestern United States and Mexico, where it is converting desert scrub to grassland. Unsuitable as a pasture grass, it has become a troublesome weed. Habitat. Tolerant of many conditions, fountain grass can be found growing on several habitats, from lava flows to rangeland, in a wide elevation range. Plants grow up to 2,000 ft. (600 m) elevation in desert areas of California and Arizona, and in Hawai’i, from sea level to the subalpine zone at 9,185 ft. (2,800 m). It is very drought tolerant and grows where annual precipitation is less than 50 in. (1,270 mm). It is a common desert plant in grasslands, washes, canyons, and roadsides. In California, fountain grass is found on disturbed coastal dunes, coastal sage scrub, and inland desert canyons and shrubland. In spite of its coastal locations, it does not tolerate saline soils. Roadsides are an especially common habitat near urban centers where ornamental plants have escaped cultivation. Seeds also germinate and grow in rock crevices and broken pavement. Reproduction and Dispersal. Fountain grass can produce viable seeds with or without fertilization. Pollination is not necessary because the female plants can produce seeds asexually, from other plant cells, not just from egg cells. However, even when flowers are pollinated, few seeds develop. Seeds are wind dispersed and remain viable in the soil at least seven years. Long-distance dispersal takes place by water, vehicles, livestock, and human activity. Plants grow quickly. In just five years, a plant can become 4 ft. (1.2 m) tall, with a basal diameter of 12 in. (30 cm). Individual plants may live for 20 years.

462 n GRAMINOIDS Impacts. In addition to replacing native plant species, the most serious impact of fountain grass is how it changes fire regimes. Plants accumulate dead biomass, providing more fuel, which results in increased intensity and spread of fires. It is an aggressive, fire-adapted invader that quickly colonizes burned areas and outcompetes native plants, eventually creating single-species stands. As a major threat to Hawaiian ecosystems, it replaces native species not adapted to fire. Fountain grass can cause forests in Hawai’i to convert to grassland, and it can replace coastal sage in California. Management. Because seeds are long lived, continued monitoring of a site is necessary. Control should begin at the edges of infestations, to prevent it from spreading further. Once fountain grass is successfully removed, it is important to reseed with native species. Physical removal by hand-pulling is only feasible in small stands or with small plants. It is difficult to break up plants that have a base larger than 6 in. (15 cm) in diameter. Handpulling should be done several times a year to prevent new sprouts from becoming established. The inflorescence must be properly disposed of, such as placing in plastic bags, to prevent seed dispersal. Because fountain grass is fire adapted, burning is a very poor option. Chemical control may be effective when used in combination with physical methods. Preemergents, such as hexazinone, used after plants have been removed will prevent seeds from sprouting for 9–12 months. A systemic, such as glyphosate, applied to leaves does not provide consistent results. Nothing has been proposed for biological control of fountain grass. Any insects would most likely also affect related forage and crops, such as kikuyugrass and pearl millet. Although kikuyu grass (see Graminoids, Kikuyugrass) is also an invasive pest in some regions, it is an important forage crop for cattle in Hawai’i.

Selected References Benton, Nancy. “Fountain Grass.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2009. http://www.nps.gov/archive/plants/ alien/fact/pese1.htm. IUCN SSC Invasive Species Specialist Group (ISSG). “Cenchrus setaceus (Grass).” ISSG Global Invasive Species Database. 2010. http://www.issg.org/database/species/ecology.asp?si=309. Lovich, Jeffrey. “Pennisetum setaceum.” In Invasive Plants of California’s Wildland, edited by Carla C. Bossard, John M. Randall, and Marc C. Hoshovsky. Berkeley: University of California Press, 2000. http://www.cal-ipc.org/ip/management/ipcw/pages/detailreport.cfm@usernumber=66&survey number=182.php.

n Giant Reed Also known as: Arundo, Spanish reed, wild cane, carrizo Scientific name: Arundo donax Synonyms: Arundo versicolor Family: Grass (Poaceae) Native Range. Eastern Asia, northern India, and Nepal. Introduced to and cultivated in other regions of Asia, southern Europe, North Africa, and the Middle East for thousands of years. Distribution in the United States. Southern half of the United States, from Illinois south to the Gulf of Mexico and from the Atlantic Ocean to the Pacific Ocean. Primarily problematic along waterways in the desert states.

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Description. One of the largest herbaceous species in the grass family, giant reed is a perennial that grows 6.5–30 ft. (2– 9 m) tall. Smooth stalks are 0.25–2 in. (0.6–5 cm) thick and hollow between the nodes. After the first year of growth, stems branch sparingly from the nodes. Continually cutting the culms causes the plant to branch profusely. Pale, green or blue-green leaves, which may be either flat or folded, grow alternately all along the stalk and are two-ranked, meaning that they grow on opposite sides of the stem, not all around it. The leaf blades are long, 1–2 ft. (0.3–0.6 m), and narrow, 1–2.5 in. (2.5–6 cm) wide, gradually tapering to a point. The bases of the leaves where they join the stalk are heart-shaped with a hairy tuft. Leaf margins are rough to the touch. Roots are tough and fibrous, penetrating deeply into the soil. Creeping rhizomes are thick and fleshy. Long, 2–3 ft. (0.6–1 m), plumes of cream or light-brown Giant reed colonizes moist areas along ditches and riverbanks. (Native flowers, borne in a panicle at range approximated from USDA GRIN and selected references. the top of the stalks, appear as Introduced range adapted from USDA PLANTS Database, Invasive Plant early as March, but mostly in Atlas of the United States, and selected references.) August and September. Many spikelets, 0.5 in. (1.2 cm) long with several florets, branch from the flower stalk. Flowers are densely packed on the inflorescence, and spikelet branches are upright, not drooping. Related or Similar Species. Giant reed resembles other tall members of the grass family, including bamboo, cultivated corn, and common reed (see Graminoids, Common Reed). Common reed also has smooth, hollow stems, but the leafy stems do not branch. Inflorescences are purple or golden, in a bushy panicle usually 12 in. (30 cm) long. Introduction History. Because it has useful properties, giant reed was intentionally introduced to North America, probably by the Spanish, and has also been introduced to most subtropical and warm temperate areas of the world. It was purposely planted on streambanks to control erosion and as an ornamental in warmer areas of the United States. Stalks and leaves were also used for fencing, thatching, and other building materials. It was first known in the Los Angeles area in the early 1800s.

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A. Plants can be as tall as 30 ft. (9 m). (Chuck Bargeron, University of Georgia, Bugwood.org.) B. Leaves are tworanked on the stem. (James H. Miller, USDA Forest Service, Bugwood.org.) C. The large inflorescence is a feathery panicle. (David J. Moorhead, University of Georgia, Bugwood.org.) D. The heart-shaped ligules are hairy. (Amy Ferriter, State of Idaho, Bugwood.org.) E. Culms grow in dense stands. (Bonnie Million, BLM, Ely District, Bugwood.org.) F. Buds on the rhizomes sprout many new plants. (Joseph M. DiTomaso, University of California–Davis, Bugwood.org.)

Habitat. Giant cane grows best in moist conditions, where water is available but soil is well drained. Riparian environments along ditches, streams, and riverbanks are ideal. Plants also tolerate both a high water table and dry upland areas along roads. Any type of soil is suitable, from clay to sand, and plants are tolerant of saline conditions. Although young plants are susceptible to drought, stands older than 2–3 years can withstand dry conditions because roots are not only drought resistant, but extend deep into the soil to extract moisture. Plants can survive low temperatures when dormant but not when growing. They are damaged by spring frosts. Reproduction and Dispersal. Not much is known about the viability of seeds or germination requirements, but studies have shown that seeds produced from plants in California are not viable. Commercial stands are planted by use of rhizomes, and natural reproduction is almost exclusively vegetative. Giant reed spreads when stem and root fragments float downstream. Floods break off pieces of the rhizomes or stalks, and any that contain nodes will readily sprout a new plant. Impacts. Giant reed causes a number of problems, including flooding, erosion, habitat loss, and increased fire danger. The plant forms dense thickets that clog stream channels and ditches. One clump can cover several acres. Root masses can be more than 3.3 ft. (1 m) thick, stabilizing banks and altering stream flow. The interconnecting roots form mats that block water flow under bridges and into culverts, where eventually the weight of the mat and trapped debris can damage structures. In contrast to bank stabilization, giant reed may increase bank erosion. During flood events, masses of vegetation can break off from the bank, with the entrwined roots and rhizomes carrying the soil as well. Because the plant grows very fast, up to 2 in. (5 cm) a day, giant reed outcompetes and totally displaces native plants, which reduces habitat for wildlife, including federal endangered species such as Least Bell’s Vireo and Willow Flycatcher in California. Native stands of willows and cottonwoods depend on periodic flooding and redeposition of silt, which is required for the evolution of the flood plain community. The resultant diversity in the plant community

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is necessary as nesting sites for several species of birds. Giant reed provides no food or nesting sites for natives. Leaves of giant reed contain noxious chemicals such as alkaloids, which give the plant natural protection from insects and grazers, another reason why the plant does not support wildlife. Stands of giant reed provide less shade than do native riparian plants, resulting in higher water temperature that limits aquatic diversity, including fish species. Because giant reed produces abundant plant material that is highly flammable, especially when dry, fire potential in normally moist riparian habitats is increased. In wild stands of giant reed, the amount of dried plant material per acre can be as much as 8.3 tons (20 tons per ha). Whereas the moist native vegetation serves as a firebreak, the flammable giant reed does not. Its height also leads flames into crown fires in nearby vegetation. Buried rhizomes quickly send up new shoots after a fire, outcompeting native plants. Because of its large size and mass, giant reed stands consume a considerable amount of water in arid regions. Management. A watershed approach must be used to control or eradicate giant reed. Eradication of all plants and rhizomes in the upper reaches of streams will prevent reestablishment of the plant downstream. Physical removal must include total removal of all plant debris to prevent fragments of stems or rhizomes from re-infesting the site. However, cut and dried chips will not sprout. Hand removal, although useful for small sites because it is selective, is labor intensive and expensive. Roots and rhizomes must be dug out. Mechanical removal by cutting or mowing is not selective and appropriate only for pure stands of giant reed where no native vegetation remains. Repeated mowing to deplete root reserves may be effective. If only one mowing can be accomplished, it is best done just before flowering to prevent production of any seeds. Prescribed burning, whether done selectively or not, should be done after flowering. Although fire does not destroy the roots, it may destroy the seed bank in the soil. Grazing is not a preferred method of reducing plant mass. Cattle find giant cane unpalatable, but will eat it during the dry season. Angora goats, and possibly sheep, are better options. Any physical removal should be followed by chemical application, with a herbicide that is appropriate for use in wetlands or riparian habitats. Systemic herbicides, such as glyphosate, should be applied on the whole plant after flowering but before dormancy, in mid-August to early November, when plants are actively translocating nutrients to the roots. Herbicides can also be applied on cut stalks or new growth. Areas may be reseeded with natives after the cane density has been reduced.

Beneficial Uses of Giant Reed

G

iant reed has been used by civilizations for thousands of years. Use for thatching and building materials is widespread. Ancient Egyptians lined grain storage pits with leaves and sometimes wrapped mummies in the leaves. It has been used in construction of musical instruments, such as pan pipes and bagpipes. Because no good substitute exists, giant reed is still grown commercially, especially in Argentina, China, Australia, Spain, Italy, and France, as a source of reeds for use in musical instruments. Rhizomes are beneficial in medicine, as a sudorific, diuretic, and antilactant. Additional uses include basketry, fishing rods, trellises, poultry pens, and fodder.

466 n GRAMINOIDS Little is known about insect predators or pathogens that can be used for biological control. The green bug (Schizaphiz graminum) feeds on giant cane in winter. Phothedes dulcis caterpillars in France may eat it, as will Zyginidia guyumi in Pakistan. A moth borer (Diatraea saccharalis) may be effective in Barbados. In the Mediterranean region, some damage occurs from corn borers, aphids, and spider mites. In the United States, plants are somewhat susceptible to root rot, lesions, crown rust, and stem speckle, but all result in little damage.

Selected References Bell, Gary P. Ecology and Management of Arundo donax, and Approaches to Riparian Habitat Restoration in Southern California. Santa Fe: Nature Conservancy of New Mexico, 2002. http://www.invasive.org/ gist/moredocs/arudon01.rtf. Benton, Nancy, Gary Bell, and Jil Swearingen. “Giant Reed.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2009. http:// www.nps.gov/plants/ALIEN/fact/ardo1.htm. Dudley, Tom L. “Arundo donax.” In Invasive Plants of California’s Wildlands, edited by Carla C. Bossard, John M. Randall, and Marc C. Hoshovksy. Berkeley: University of California Press, 2000. http://www.cal-ipc.org/ip/management/ipcw/pages/detailreport.cfm@usernumber=8&survey number=182.php. Hoshovsky, Marc. “Element Stewardship Abstract for Arundo donax.” Global Invasive Species Team, Nature Conservancy, 1996. http://www.invasive.org/gist/esadocs/documnts/arundon.pdf.

n Japanese Stilt Grass Also known as: Chinese packing grass, Nepalese browntop, eulalia Scientific name: Microstegium vimineum Synonyms: Eulalia viminea, Andropogon vimineum, Microstegium imberbe Family: Grass (Poaceae) Native Range. Southeastern part of Asia, including southern China, Korea, Japan, Taiwan, Southeast Asia, and the Philippines. Distribution in the United States. Most states east of the Mississippi River and along the Gulf coast, north to southern New England, and continuing to spread northward. Description. Growing in dense mats, Japanese stilt grass is a sprawling annual grass that can be 1–3.5 ft. (0.3–1 m) tall. The usually decumbent stems are as long as 3.3 ft. (1 m). The stems are weak, usually branched, smooth, and glabrous. The pale, lime-green leaves, alternate on the stem, are lance shaped, 1–3 in. (2.5–8 cm) long and as wide as 0.5 in. (1.25 cm). Leaves are distinctly tapered at each end, causing the plant to resemble a small bamboo. Both leaf surfaces are sparsely pubescent, and the leaf’s midrib on the upper surface has a palesilver stripe of reflective hairs that make it shiny. The ligules are membranous and fringed with short hairs. Plants take on a slight purple tinge in fall before dying. Roots are shallow, and stems root where nodes touch the ground. Appearing late summer to early fall, the inflorescence is a spike-like panicle with 1–6 racemes, each 1–3 in. (2.5–7.5 cm) long. Plants have multiple inflorescences, both from the end of the stem and from axils where the stems branch. The spikelets occur in pairs and are coarsely hairy. Glumes are 0.2 in. (5 mm) long, with no awns. The lemmas either have no awn or a slender awn, 0.1–0.3 in. (4–8 mm) long. Florets on the inflorescence at the end of the stem are chasmogamous (cross-pollinated), while those on the inflorescences in the axils are cleistogamous (self-pollinated). Small yellowish reddish seeds ripen from September to November.

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Related or Similar Species. Virginia cutgrass, also called white grass, which often grows with and resembles Japanese stilt grass, can be distinguished by its glabrous leaf sheaths, spikelets with only one flower, and lemmas that sometimes have a hairy fringe. Jointed grass, an invasive alien species, has short, broad leaves, 2.5 in. (6.3 cm) long and 0.75 in. (2 cm) wide, with hairy leaf bases that encircle the stem. Introduction History. Japanese stilt grass was first collected in Tennessee in 1919. It spread rapidly, and, by 1960, was present in several midwestern, southeastern, and Atlantic states. It appears to be expanding its range and was recently found along the Hudson River in New York and in Connecticut. Its use as packing material to protect porcelain shipments from Asia is the probable cause of its initial introduction, and it most likely was dispersed in transported hay or soil. Habitat. Adapted to low light conditions, the plant pre- Tolerant of both light and shade, Japanese stilt grass may form mats in fers shady, moist locations and both open areas and woodlands in southeastern states. (Native range is commonly found in wood- adapted from USDA GRIN and selected references. Introduced range lands near streams, forested adapted from USDA PLANTS Database, Invasive Plant Atlas of the wetlands, floodplains, and United States, and selected references.) swamps. Also able to grow in high light and moderately dry soils, it grows in uplands, such as fields, clearings, paths, seldom-used roadbeds, and road and utility right-of-ways. Japanese stiltgrass does not tolerate wet soil or standing water and does not grow in clay soils. It invades primarily acidic to neutral soils with high nitrogen content, but can also be found on neutral soils overlying limestone and marble. It easily invades areas that are regularly mowed, tilled, subject to foot traffic, or affected by any action that causes a soil disturbance. Naturally disturbed areas, such as scoured stream beds or banks caused by flooding, may also be invaded. A disturbance to a forest that creates a canopy opening will also stimulate the plant to spread. Upland forests in Pennsylvania were colonized after defoliation by gypsy moth. The coldest winter temperature where populations of Japanese stilt grass are considered to be invasive is approximately −7ºF (−22ºC).

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A. This groundcover is a monotypic stand of Japanese stilt grass. (Chris Evans, River to River CWMA, Bugwood.org.) B. Decumbent stems grow in a dense mat. (Chuck Bargeron, University of Georgia, Bugwood.org.) C. Florets grow close to the stem. (Leslie J. Mehrhoff, Ecology and Evolutionary Biology University of Connecticut, Bugwood.org.) D. Lance-shaped leaves taper to a point at both ends. (David J. Moorhead, University of Georgia, Bugwood.org.)

Reproduction and Dispersal. Japanese stilt grass reproduces both sexually and asexually. Seeds are most likely responsible for populations that develop in new locations, but the plant’s ability to root at stem nodes explains its ability to colonize large areas. Although one plant is capable of producing more than 1,000 seeds, 100 is the norm. Seeds have no obvious mode of dispersal, and most fall close to the parent. They may be dispersed by water flow during heavy rains and are frequent contaminants in hay, soil, or potted plants. Seeds may also adhere to vehicles and shoes. Although the grass is not eaten by deer and other browsers or grazers, those animals may aid in seed dispersal. Seeds remain viable in the soil for seven or more years and can survive 10 weeks of submergence in water. Seeds germinate in spring, and seedlings grow slowly during the summer. Impacts. Japanese stilt grass can spread extensively to create dense, monotypic stands. In disturbed areas, the grass can shade out and replace herbaceous ground cover in 3–5 years. It grows more slowly in undisturbed sites. It crowds out and displaces native herbaceous species in wetlands and forest floors. By changing the character of forest understory habitat, it negatively affects ground-nesting birds. It replaces the nesting habitat of native Bobwhite Quail and other wildlife, but provides good habitat for predators of ground-nesting birds, especially cotton rats. The annual dieback of the grass results in a thick layer of thatch on the ground. Although the leaves decompose quickly, the stems do not. Plants can alter soil chemistry. Litter and organic horizons become thinner, and the pH is higher. It is possible that Japanese stilt grass could negatively impact populations of the northern pearly eye butterfly along the Potomac River in the Washington, D.C., area. The butterfly has been observed laying eggs on Japanese stilt grass as an alternative host plant for its caterpillars, but the relationship is not yet clear. White-tailed deer selectively feed on native grasses, reducing competition and encouraging Japanese stilt grass to spread. Management. Management priority should be to prevent Japanese stilt grass introduction into noninfested areas. Because it is an annual with a shallow root system, physical removal is feasible. Hand-pulling is best accomplished in mid-to-late summer when plants are larger, and it is too late in the season for more seeds to germinate a new crop. Removing plants before early July triggers sprouting from the soil seed bank. Pulled plants may be left to dry on the surface, but plants in the fruiting stage should be bagged and disposed offsite. Repetition of hand removal methods for several years will exhaust the seed bank. Mowing

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the grass in late summer, August and September, while the plants are in flower, but before seed sets, will ensure that plants do not resprout the same season. Grazing is not an option because livestock, even goats, do not eat it. Flooding for more than three months during the growing season will kill mature plants but will not affect the seed bank. Prescribed burning in spring stimulates germination from the seed bank, but burning in late fall may be beneficial in that it reduces the thatch layer. Burning the litter layer before application of herbicides will allow the herbicides to reach more actively growing plants. Chemical applications of systemics, such as glyphosate, are practical for large infestations. The preemergent imazapic has been effective in controlling Japanese stilt grass in some regions, with the advantage that it can be sprayed throughout the summer. No biological controls are known.

Selected References “Invasive Plant, Japanese Stilt Grass (Microstegium vimineum).” The Nature Conservancy in Connecticut, 2010. http://www.nature.org/wherewework/northamerica/states/connecticut/science/ art24048.html. “Japanese Stilt Grass.” New Invasive Plants of the Midwest Fact Sheet. Midwest Invasive Plant Network, n.d. http://mipn.org/Midwest%20Invasives%20Fact%20Sheets/PDF/Japstilt.pdf. Swearingen, Jil M. and Sheherezade Adams. “Japanese Stiltgrass.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2009. http:// www.nps.gov/plants/alien/fact/mivi1.htm. Tu, Mandy, ed., and John Randall. “Element Stewardship Abstract, Microstegium vimineum.” Global Invasive Species Team, Nature Conservancy, 2000. http://wiki.bugwood.org/Microstegium _vimineum.

n Johnsongrass Also known as: Aleppo grass, Johnson grass Scientific name: Sorghum halepense Synonyms: Sorghum miliaceum, Holcus halapensis Family: Grass (Poaceae) Native Range. Mediterranean region of northeastern Africa and Southwest Asia. Possibly native to the desert areas as far east as Pakistan. Distribution in the United States. Every state except Maine, Minnesota, and Alaska. Description. Johnsongrass is a coarse, tall perennial grass that grows as high as 3–8 ft. (1–2.4 m). It can form dense clumps, with stems branching from the base, or nearly solid stands from the extensive growth of rhizomes. Stems are pink or reddish near the base. Leaf sheaths are glabrous, but the membranous ligules have a white fringe. The smooth leaves, alternate on the stem, are 0.6–2 ft. (0.2–0.6 m) long and 0.4–1.2 in. (1–3 cm) wide, with rough margins. Leaves are distinguished by a prominent white midrib on the upper surface. The fleshy rhizomes, as much as 0.4 in. (1 cm) in diameter and 6.5 ft. (2 m) long, are scaly and sharply pointed. Most are in the top 8 in. (20 cm) of soil, but the rhizome mass is deeper in light-textured soils and closer to the surface in heavy clay soils. Rhizomes attain a much greater biomass than stems and leaves and may be as much as 90 percent of the total weight of the plant. Flowering occurs throughout the growing season, usually April to November. Flowers occur in loosely branched panicles, 6–20 in. (15–50 cm) long. The numerous panicle

470 n GRAMINOIDS branches grow upright and whorled around the stem. The inflorescence is purplish and hairy, with short spikelets at the ends of the branches. Spikelets, 0.2 in. (5 mm) long, grow in pairs, or occasionally in groups of three, each with a conspicuous awn. Although each spikelet produces one seed, plants produce many reddish-brown seeds, 0.1 in. (3 mm) long and with a conspicuous awn. Seeds ripen from May through March. Related or Similar Species. Sorghum, also known as shattercane, is originally from northern Africa. The species and its cultivars, either annual or perennial, are cultivated for the edible grain. Although invasive in several states, this plant lacks creeping rhizomes. Sudangrass, a subspecies of sorghum, is an annual. Although available for sale as an ornamental, it is also invasive in some areas. Bulb panicgrass, frequently mistaken for Johnsongrass, can be distinguished Johnsongrass, a weed in both crops and natural ecosystems, is especially by swollen tissue at the base of problematic along the Gulf coast. (Native range adapted from USDA the culms and its much shorter GRIN and selected references. Introduced range adapted from USDA rhizomes. PLANTS Database, Invasive Plant Atlas of the United States, and selected Introduction History. Widely references.) used in the world as a forage crop, Johnsongrass was brought to Carolina from Turkey in the early 1800s. It is called Johnsongrass because a farmer named Johnson took the plant from South Carolina to Alabama in 1840. By the end of the nineteenth century, Johnsongrass had spread to most of the United States. Because it can be a nutritious fodder under the right growing conditions, it has been promoted as a forage plant. Its spreading rhizomes make it useful for erosion control. Habitat. Originally preferring Mediterranean or tropical climates, Johnsongrass has evolved new ecotypes that enable it to grow in many environments and continue to expand its range. Most ecotypes are frost sensitive, but some can overwinter in warmer climate zones. The aerial parts of the plant die back in colder winter regions, but the rhizomes may persist. Cold-tolerant ecotypes have been discovered in the northern United States and in Canada.

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A. Johnsongrass grows in dense clumps that can be 8 ft. (1.2 m) tall. (Chris Evans, River to River CWMA, Bugwood.org.) B. Leaf blades have a prominent white midrib. (Chris Evans, River to River CWMA, Bugwood.org.) C. Flowers are open panicles. (James H. Miller, USDA Forest Service, Bugwood.org.) D. Rhizomes are pointed and scaly. (Steve Dewey, Utah State University, Bugwood.org.) E. Seeds are plentiful. (Steve Dewey, Utah State University, Bugwood.org.)

Johnsongrass is most common in agricultural land, such as crops, pasture, and abandoned fields, and in disturbed areas, such as right-of-ways, irrigated ditches, and the trampled land around springs and stock tanks. It also grows at forest edges and in wetlands, but requires open areas and is not found under closed canopies. It thrives in disturbed open lowlands with rich soils, particularly cultivated fields. It grows best on moist, porous soils and less vigorously on poorly drained clays. The rhizomes are intolerant of hot, dry conditions and may be killed by exposure. Reproduction and Dispersal. Johnsongrass produces both sexually and vegetatively. Plants are self-fertile, which accounts for most of the seed production. It is a short-day plant; more seeds are produced when daylight hours are fewer than 12. Seed production also depends on the ecotype, varying 40–350 seeds per panicle. Seeds are spread by water and wind, and strong winds in thunderstorms can carry seed as far as 0.6 mi. (1 km) distant. The twisted awns are frequently found on farm equipment or caught in the coats of livestock. Seeds are able to survive the intestinal tract of birds or livestock, and are also a contaminant in hay and commercial seed. Most seeds germinate the year after they are produced. Although dormancy varies with the ecotype, some seeds enter dormancy immediately after ripening, with 50 percent capable of germination after five years. After six years, viability drops to 2 percent. Germination is best at 77–86ºF (25–30ºC), in light soils from a depth less than 3 in. (7 cm). Rhizomes, which root at nodes, begin to grow 30–45 days after seeds germinate. They grow more rapidly than shoots, and one plant can produce a total rhizome length of 200– 300 ft. (60–90 m) in one month. Shoots can emerge from rhizomes 4 ft. (1.2 m) deep in the soil, and any small piece is capable of sprouting a new plant. Rhizomes may remain dormant until conditions cause the buds to sprout. Impacts. Considered by some to be one of the 10 worst weeds in the world, Johnsongrass causes problems in most of the populated regions of the world, between 55º N and 45º S latitudes, and is particularly troublesome along the Gulf coast of the United States. Its impacts on both natural ecosystems and agriculture are many and varied. It forms dense colonies, which displace native plant species and restrict the establishment of tree seedlings, affecting natural succession. As a weed in cultivated fields, it shades out crops and deprives them of needed moisture and nutrients. It is also alleleopathic to several

472 n GRAMINOIDS crop species, including corn, sugar cane, grain sorghum, soybeans, sunflowers, wheat, barley, mustard, citrus, and cotton. It is an alternate host for insect, fungal, bacterial, and nematode pathogens that affect crops. Its flowers cross-pollinate with S. bicolor, reducing yields of commercial sorghum crops. Ingestion of Johnsongrass by livestock is very toxic, especially when plants are stressed, and can be fatal. Glycosides in the plant are converted into free cyanide in the digestive system of livestock. Certain feeds, such as alfalfa hay and linseed cake, provided along with Johnsongrass may retard the development of free cyanide. Cyanide is a rapidly acting poison, and symptoms can manifest just five minutes after the plant is ingested. Death can occur in 15 minutes or after several hours. Symptoms may begin with salivation and labored breathing, then progress to muscle tremors and incoordination. Venous blood becomes bright red, and convulsions and death may follow. Plants can also accumulate toxic amounts of nitrate, which causes poisoning in sheep and cattle. Animals can be treated for both cyanide and nitrate poisoning. Rarely, Johnsongrass can cause sorghum cystitis in horses, a disorder that permanently damages the spinal cord. The animal then loses control of its rear legs and bladder. Few horses that eat the plant are affected, and the cause is not known. No treatment exists, and the animal must be euthanized. The excessive amount of dried plant matter can be a fire hazard in summer, and the pollen is a known allergen. Management. Control of Johnsongrass is difficult, and eradication almost impossible because of the plant’s extensive rhizome system, its abundance of seeds, and ability to grow in various climates or environments. The best management is prevention, by maintaining land in an undisturbed state. Any physical control should avoid soil disturbance. Light infestations may be eliminated by hand-pulling. Plants should be pulled in June and all parts removed. Heavy infestations may be mowed or tilled. Frequent summer mowing may deplete rhizome reserves and prevent seed production. Mowing or grazing that keeps plants shorter than 12 in. (30 cm) tall may deplete the rhizomes stores and kill plants within 2–3 years. Winter cultivation will expose rhizomes to the fatal effects of cold temperatures. Cultivation early in the growing season, however, will spread rhizomes and make the infestation worse. Burning encourages regrowth. Solarization may provide some success. Covering infested areas with black plastic in hot climates will increase temperatures to a level where even the rhizomes die. Chemical applications of herbicides such as glyphosate for several years may be effective. No biological controls are known.

Selected References IUCN SSC Invasive Species Specialist Group (ISSG). “Sorghum halepense (Grass).” ISSG Global Invasive Species Database, 2005. http://www.issg.org/database/species/ecology.asp?si=213&fr=1&sts=sss. “Johnsongrass.” Toxic Plants of Texas. Texas AgriLife Extension Service, n.d. http://essmextension .tamu.edu/plants/toxics/detail.aspx?plantID=79. Newman, Dara. “Element Stewardship Abstract, Sorghum halepense.” Global Invasive Species Team, Nature Conservancy, 1993; updated 2009. http://wiki.bugwood.org/Sorghum_halepense.

n Jubata Grass Also known as: Andes grass, Andean pampas grass, selloa, cortaderia, pink pampas grass, purple pampas grass Scientific name: Cortaderia jubata Synonyms: Cortaderia atacamensis, Gynerium jubatum

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n Pampas Grass Also known as: Uruguayan pampas grass, silver pampas grass Scientific name: Cortaderia selloana Synonyms: Arundo selloana, C. argentea, C. dioica, Gynerium argentium Family: Grass (Poaceae) Native Range. Jubata grass is native to Northern Argentina and the Andes of Bolivia, Chile, Peru, and Ecuador, from sea level to over 11,000 ft. (3,400 m) elevation. Pampas grass is native to Argentina, Brazil, and Uruguay, in damp river margin soils. Distribution in the United States. Jubata grass grows in coastal California, Oregon, Washington and in Texas and Hawai’i. Pampas grass is found in the Pacific coast states of California, Oregon, and Washington; in the desert and mountain states of Arizona, New Mexico, Utah, and Colorado; and in the southeastern states from Texas to Virginia. Also in Hawai’i. Description. Jubata grass and its close relative pampas grass are often confused. Both are large tufted perennial grasses with leaves rising from a tussock and have a long feather-like, plumed panicle extending above the leaves. Leaves are glabrous on both upper and lower surfaces, and leaf margins are sharply serrated. The two species, however, are distinguishable by many characteristics, including stem height, details of leaves and flowers, and method of reproduction. Jubata Grass: The leaves of jubata grass are more spreading or drooping than erect, resulting in a shorter and broader plant than pampas grass. The leaf sheath of the bright-green to deep-green leaves is densely hairy, and the leaf tip is not bristled or curled. Leaf blades, Although a more aggressive invader than pampas grass, jubata grass is which are 3–5 ft. (1–1.5 m) limited to frost-free areas in western states. (Native range adapted from long and 0.8–4 in. (2–10 cm) USDA GRIN and selected references. Introduced range adapted from wide, may be flat or slightly V- USDA PLANTS Database, Invasive Plant Atlas of the United States, and selected references.) shaped in cross-section.

474 n GRAMINOIDS Although roots are fibrous, clustered around a crown not far beneath the surface, they may be either fine or thick. Plants flower from July to September. The inflorescence stem typically rises 3–6 ft. (1– 2 m) above the tussock, and the panicle itself is 1–3 ft. (0.3–1 m) long. The flower stalk is generally 2–4 times the height of the tussock. Jubata grass produces only female flowers, which are initially deep violet or purple, fading to pinkish or tan when mature. Spikelets are 0.6 in. (15 mm) long, with 3–5 florets each. Florets have hairs, 0.2–0.4 in. (6– 10 mm) long, on the base of the lemma, and the short awns, less than 0.04 in. (less than 1 mm), extend only slightly beyond the hairs. The stigma extends very little beyond the awns, and the glumes are purple. The ripened seed is easily separated from the rachilla. Pampas Grass: Leaves of pampas grass are more erect, resulting in a taller plant, Pampas grass is widely used as an ornamental and is still expanding its 6–13 ft. (2–4 m), not including range. (Native range adapted from USDA GRIN and selected references. the inflorescences. Leaves, as Introduced range adapted from USDA PLANTS Database, Invasive Plant long as 6 ft. (2 m) and 1–3 in. Atlas of the United States, and selected references.) (3–8 cm) wide, are a bluish green, with a tapering tip that is bristly and curled. They are somewhat folded at the midrib, giving them a V-shape profile. The sheath can be glabrous or variably hairy. Tussocks can be 9.8–16.4 ft. (3–5 m) in diameter. Roots of each established plant can fill about 1,100 sq. ft. (103 m2) of soil. Lateral roots spread as far as 13 ft. (4 m) from the parent plant, and taproots can extend 11.5 ft. (3.5 m) deep. Plants flower during August and September, with male and female flowers on separate plants. Although flower stalks may be no higher than the height of the tussock leaves, they are usually taller. Generally, the length of the flower stalk is equal to the height of the tussock. The flower stalks in female plants may reach 3 ft. (1 m) high above the tussock, and the male flower stems can be larger, as high as 6 ft. (2 m) above the tussock. The plume color of female plants is light violet to silvery or creamy white, while the plumes of male plants are a slightly darker violet. The inflorescence bears many spikelets, each 0.6 in. (15 mm) long.

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A. The drooping nature of the stems of jubata grass results in a wide plant. (Joseph M. DiTomaso, University of California–Davis, Bugwood.org.) B. Jubata grass leaf sheaths are hairy. (Joseph M. DiTomaso, University of California–Davis, Bugwood.org.) C. Flowers on the panicle of jubata grass are all female. (Joseph M. DiTomaso, University of California–Davis, Bugwood.org.) D. Culms of pampas grass grow more erect. (Forest and Kim Starr.) E. Pampas grass leaf sheaths are usually glabrous. (Joseph M. DiTomaso, University of California–Davis, Bugwood.org.) F. The female panicle (left) of pampas grass is larger and more showy than the male inflorescence (right). (Joseph M. DiTomaso, University of California–Davis, Bugwood.org.)

Female plants have 5–7 florets per spikelet, which have dense hairs, 0.04–0.4 in. (1–10 mm) long, at the base of the lemmas. The 3–5 florets on male plants have few to no hairs. Awns, 0.2–0.5 in. (5–12 mm), on female flowers are twice the length of the hairs. The stigma, about twice the length of the awns, extends beyond them. Glumes on the spikelet are white. Mature seed is not easily separated from the rachilla. Plants seldom produce seed because most ornamental plants are female. Related or Similar Species. Toe toe, also called Richard’s pampas grass, is native to New Zealand and widely available on the Internet. A clump-forming perennial, it grows to 9 ft. (2.7 m) tall and 6.5 ft. (2 m) wide. The arching leaves are stiff, leathery, and glabrous. The inflorescence is a plume of creamy flowers that can be almost 10 ft. (3 m) tall. Introduction History. Jubata grass was first used as an ornamental in France and Ireland, and probably reached California in horticultural trade from France at an unknown date. Although first recognized as a weed in California in the 1950s when it escaped cultivation, it was not until 1966 that it was first reported as a problem in logged redwood forests of northern California. Nurseries often sell jubata grass as “pampas grass.” The first confirmed record of jubata grass in Hawai’i was in 1991.

476 n GRAMINOIDS Pampas grass was taken as an ornamental to Santa Barbara, California, in 1848. By 1895, Santa Barbara nurseries were primary producers that shipped plants worldwide. In 1946, the U.S. Soil Conservation Service planted pampas grass in Ventura County and Los Angeles County for dryland forage and erosion control. Selected for the showy female plumes, plants were propagated vegetatively by division. More recently, plants have been produced by seed, and because the sex of the plant cannot be determined until it blooms, both male and female plants are currently sold as ornamentals. Because more males have now been planted, pampas grass is producing more seed. Although pampas grass was introduced to Hawai’i in 1925 as an ornamental, jubata grass was the only Cortaderia species identified in Hawai’i until 1998. Habitat. In California, jubata grass is found only in the coastal fog belt below 2,600 ft. (800 m). It cannot tolerate frost, hot summers, or intense sun or drought. It prefers bare or disturbed sites, such as roadcuts, forest clearcuts, landslides, cliffs, eroded soil, or burned areas. Although it does best on sandy soils, it is capable of growing on a wide range of substrate, including serpentine, with either low or high moisture. It grows in full sun to dense shade, but cannot survive in redwood forest shade. It cannot colonize healthy native grasslands. On Mau’i, jubata grass grows from 2,000–7,000 ft. (660–2150 m) elevation, with as little as 19.5 in. (500 mm) of annual rainfall. Pampas grass is most commonly found below 1,000 ft. (330 m) elevation along the California coast. Although tolerant of a wide variety of soils, it prefers deep sandy soils, moist but with good drainage. It also grows in disturbed areas, roads and trails, and rightof-ways. Although currently less extensive than jubata grass, it is still expanding its range. Because pampas grass tolerates winter frost, warmer summers, more intense sun, and moderate drought, it is used as an ornamental in the dry Central Valley of California, where it is not invasive. Reproduction and Dispersal. Jubata grass is apomictic, meaning that the female flowers produce seeds without pollination. Year-old plants can flower, and some plants can flower a second time in one season. Although it produces abundant viable seed, jubata grass has no genetic diversity because no pollen transfer takes place. One inflorescence can produce 100,000 tiny seeds, and large clumps can produce a million or more. Wind-blown seeds can be carried as far as 20 mi. (32 km). Plumes from mature plants are frequently used as decoration, a human activity that spreads seeds. Seeds can also be dispersed by water and machinery. No evidence exists of seed longevity or a soil seed bank. Germination occurs in spring, ideally on sandy soil with plenty of moisture and light. Plants can germinate when temperatures are 55–70ºF (13–21ºC). Seedlings grow best on bare soil, but need cool, foggy, moist conditions. Survival is low under shady conditions or in competition with grasses. Growth rate increases after young plants become established. New plants may also grow from tiller pieces, sometimes caught in machinery, which root in moist soil. Plants of pampas grass produce flowers 2–3 years after germination, and only produce seed when male and female plants are found together. Seeds germinate in the spring under the same requirements as jubata grass, and have a similar survival rate. Like jubata grass, each inflorescence may have 100,000 seeds on each inflorescence. Tiny seeds are dispersed primarily by wind, up to 20 mi. (32 km) distant. Plants of both species live for about 15 years. Impacts. The more aggressive of the two species, jubata grass threatens coastal ecosystems of California, particularly sensitive dune areas, by displacing native vegetation. In cutover redwood forests in northern California, it has become a weed problem where its presence interferes with establishment and growth of conifer seedlings. The buildup of dry

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plant matter, leaves and flower stalks, is a fire hazard, and large tussocks can block access and impede fire suppression efforts. The sawtoothed leaves cause injury to hikers, degrading recreational experiences. Pampas grass is a problem on the central and southern California coast, and may become more so as more seeds are produced and disseminated. Because it cross-pollinates, it is more genetically diverse than jubata grass, enabling it to adapt to a wider variety of environmental conditions and possibly expand its range. Impacts of pampas grass are similar to those of jubata grass, but not as severe. Both jubata grass and pampas grass are currently limited to small stands on Mau’i. Bare ground and cinder fields in Haleakala National Park, however, offer prime habitat. It is not known if jubata grass can consistently withstand the freezing temperatures encountered above 7,000 ft. (2,150 m) elevation, but seedlings and young plants are occasionally found, indicating a potential for invasion of montane and subalpine regions. Infestations of jubata grass have been located in pristine rainforest, the first known anywhere in the world. These sites on open, sunny ridgetops receive as much as 197 in. (5,000 mm) of rainfall. Management. Control or eradication is the same for both species. In order to preserve the native ecosystems, options for control of either grass are limited in sensitive coastal California sites or in Hawai’i rainforests and national parks. Seeding disturbed sites with desirable vegetation may help to prevent Cortaderia seeds from germinating. Mulches, such as layers of straw, on disturbed sites may also reduce germination. Physical removal is only possible with small plants or in areas where little native vegetation remains to be saved. Small seedlings may be hand-pulled, while larger plants may require a shovel or other tool. To prevent resprouting, the entire root crown must be removed. Pulled plants left lying on the surface can root if the soil is moist. For large plants, it may be necessary to cut or remove the leaves to expose the crown, which then can be dug out. Inflorescences must be removed from the site or burned to destroy the seeds, even if seeds are not yet mature. In severe, large-scale infestations, bulldozers and backhoes may be necessary to remove plants. Prescribed burns are ineffective because the growing points are protected by the deep thatch and leaves, and plants will resprout. Fire, however, can be used to remove the foliage and expose the base for other treatments. On very small scales, tarps placed over cut plants will shade out sprouts and also prevent seeds from germinating. Chemical treatment is most effective, although the amount of foliage requires a lot of contact herbicide. It is more efficient to cut the foliage and spray the new sprouts. Spot treatment with glyphosate, fluazifop, or imazapyr will kill the plant, although applications must be repeated to control resprouting. Herbicides are most effective if applied before the seed matures. An alternative to herbicides is to pour diesel oil on the root crown after the leaves have been removed. However, this method leaves an oily residue in the soil. No biological controls are known.

Selected References Chimera, Charles, Forest Starr, Kim Martz, and Lloyd Loope. “Pampas grass (Cortaderia jubata and C. selloana): An Alien Plant Report.” U.S. Geological Survey Biological Resources Division, American Water Works Association Research Foundation, and Maui County Board of Water Supply, 1999. http://www.hear.org/species/reports/corspp_fskm_awwa_report.pdf. DiTomaso, Joseph. “Cortaderia jubata.” In Invasive Plants of California’s Wildlands, edited by Carla C. Bossard, John M. Randall, and Marc C. Hoshovsky. Berkeley: University of California Press, 2000.

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Almost Eradicated

A

former residential property on Mau’i at 3,160 ft. (960 m) elevation supported 100 jubata grass clumps—landscape plants that got out of control. Tussocks were 6.5 ft. (2 m) wide and interconnected, forming barriers with razor-sharp leaves. Repeated physical control and herbicide applications over several years reduced the population. When the efforts stopped due to financial and labor limitations, however, the population rebounded.

http://www.cal-ipc.org/ip/management/ipcw/pages/detailreport.cfm@usernumber=33&survey number=182.php. DiTomaso, Joseph. “Cortaderia selloana.” In Invasive Plants of California’s Wildlands, edited by Carla C. Bossard, John M. Randall, and Marc C. Hoshovsky. Berkeley: University of California Press, 2000. http://www.cal-ipc.org/ip/management/ipcw/pages/detailreport.cfm@usernumber=35&survey number=182.php. DiTomaso, Joseph M., Evelyn Healy, Carl E. Bell, Jenifer Drewitz, and Alison Stanton. “Pampasgrass and Jubatagrass Threaten California Coastal Habitats.” Leaflet #99-1. Cooperative Extension, Weed Research and Information Center, University of California, Davis. 1999. http:// wric.ucdavis.edu/PDFs/pampasgrass%20and%20jubatagrass%20WRIC%20leaflet%2099-1.pdf. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Cortaderia jubata (Grass).” ISSG Global Invasive Species Database, 2006. http:// www.issg.org/database/species/ecology.asp?si=375&fr=1&sts=&lang=EN. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Cortaderia selloana (Grass).” ISSG Global Invasive Species Database, 2006. http:// www.issg.org/database/species/ecology.asp?fr=1&si=373.

n Kikuyugrass Also known as: West African pennisetum Scientific name: Pennisetum clandestinum Synonyms: Pennisetum inclusum, P. longstylum, P. longstylum var. clandestinum Family: Grass (Poaceae) Native Range. Highlands of tropical East Africa, from Kenya to Tanzania and the eastern Congo. Named for the Kikuyu tribe in Kenya. Distribution in the United States. California and Arizona in the western states. Also in Hawai’I and Puerto Rico. Description. Kikuyugrass is usually a low-growing perennial grass, although some culms may reach up to 1.6 ft. (0.5 m) tall. Several cultivars account for variation in size. Its prostrate stems root at the nodes, and the plant expands its coverage as a creeping, sodforming mat. Leaf blades are short, 0.5–2 in. (1.25–5 cm) and narrow. Leaf margins are rough, from tiny serrations, and the tips can be either blunt or pointed. When leaf blades first emerge, they are folded or rolled, subsequently opening to lie flat on the ground. Leaves, either glabrous or covered with sparse soft hairs, have pronounced midveins on the underside. Culms have overlapping leaf sheaths, and ligules are a fringe of white hairs. Leaf sheaths, 0.4–4 in. (1–10 cm) long, are glabrous or slightly hairy.

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Rhizomes are branched and thick, usually forming an extensive network in the top 4 in. (10 cm) of soil, but they can reach 12–15.5 in. (30–40 cm) deep. The multi-branched stolons are coarse and flattened, with many short internodes. The nodes are swollen. Many vertical leafy branches sprout from the stolons and rhizomes. Plants bloom from April to October. Flowers, if present at all, grow not on tall stems like many other Pennisetum species, but on leafy, vegetative side shoots. The small, white, or tawny-colored panicles, with 2–4 spikelets each, are inconspicuous, almost entirely hidden within the leaf sheaths, with only the stamens barely visible. The spikelets are 0.4– 0.8 in. (10–20 mm) long, graygreen to straw colored with few bristles. The dark-brown seeds form inside the leaf sheaths. Long, flexible bristles, attached to the stem below each spikelet, are dispersed with the spikelets when seeds mature. Related or Similar Species. Kikuyugrass grows best in moist sites and is especially invasive in coastal Bermuda grass also grows close areas. (Native range adapted from USDA GRIN and selected references. to the ground and propagates Introduced range adapted from USDA PLANTS Database, Invasive Plant by rapidly growing stolons as Atlas of the United States, and selected references.) long as 65.5 ft. (20 m). Leaves are longer, 1–8 in. (2.5–20 cm) and may be flat or folded. They have no distinct midvein but have rough edges. Flowering stems can be as short as 6 in. (15 cm) or as tall as 3.3 ft. (1 m). Flower spikes, 1–4 in. (2.5–10 cm) long, are prominent at the top of stems, where 2–12 are arranged in a starlike shape. Spikelets are tiny and lack awns. Seeds can develop all year in warm climates, but only in summer in cooler regions. St. Augustine grass is used as a lawn grass in much of the moist tropics. Usually 6–12 in. (15–30 cm) tall, it spreads by stolons and often forms a dense mat. Leaf blades, which are folded when young, are up to 6 in. (15 cm) long, with a blunt apex. Inflorescences are short, 2–4.5 in. (5–12 cm) tall, with 1–3 spikelets. Introduction History. Kikuyugrass was introduced to Hawai’i in 1925 as a forage crop. It was planted in California in the 1930s as a ground cover to control erosion.

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A. Although it is usually low-growing, Kikuyugrass can be more than 1.5 ft. (0.5 m) tall. (Forest and Kim Starr, U.S. Geological Survey, Bugwood.org.) B. Ligules are fringed with hairs. (Joseph M. DiTomaso, University of California–Davis, Bugwood.org.) C. Plants form a thick sod. (Steve Dewey, Utah State University, Bugwood.org.) D. Leaf blades are short. (Steve Dewey, Utah State University, Bugwood.org.) E. Creeping rhizomes root at the nodes. (Forest and Kim Starr, U.S. Geological Survey, Bugwood.org.)

Habitat. Kikuyugrass grows in a wide variety of habitats, including rangeland, grasslands, orchards, disturbed sites, urban areas, wetlands, plantation crops, and forest edges. Although it invades both dry and mesic habitats, the grass grows best under moist and humid conditions, but it needs good drainage. It is especially invasive in coastal sites. It grows in areas with mild winters and some summer moisture. It requires more than 35 in. (900 mm) of annual rainfall, but established plants can also survive long periods of drought. Because it does not tolerate dense shade, it is not found in healthy forests, but will invade wet forests after a disturbance. In Hawai’i, it is often found on volcanic soils or red tropical or subtropical soils, but tolerates most soil types. Found from 35º N to 37º S and up to 9,850 ft. (3,000 m) elevation, it can survive light frost but not sustained cold. It grows most quickly at temperatures between 70ºF and 104ºF (21–40ºC), and slowly during winter, becoming brown and dormant with frequent night frosts. Frequent defoliation by grazing or mowing causes no negative effects. Reproduction and Dispersal. Kikuyugrass reproduces vegetatively, spreading via an extensive network of rhizomes and stolons. Pieces of rhizomes or stolons are easily transported long distances on machinery or on vehicles. Although rarely produced, seeds are dispersed by wind and are also found in cow or sheep droppings. The best soil temperatures for germination are 68–86ºF (20–30ºC), and seedlings can emerge from soil depths up to 2.4 in. (6 cm). Impacts. Kikuyugrass is an aggressive invader of pasture, crops, and natural ecosystems. Its thick mats smother native vegetation, and its alleleopathic compounds prevent other plants from growing. It also invades manicured turf, such as lawns and golf courses. It can overrun agricultural areas and roadsides, and can climb over shrubs and small trees. Plants can accumulate high levels of oxalates and nitrates, which are toxic to grazers, both wildlife and livestock. The basal layer of dead leaves is a ground fire hazard. In spite of its invasive tendencies, kikuyugrass has widespread use in the world as pasture for dairy and beef cattle. It is also used for soil stabilization and erosion control and as a lawn grass. Management. Prevention of accidental spread of kikuyugrass requires that all agricultural equipment be thoroughly cleaned of all plant pieces. Although small plants can be removed

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Kikuyugrass in Peru

T

his African grass is sometimes used as a lawn grass on the terraces of Incan ruins, such as Machu picchu. Stolons from the intentional plantings, however, have overrun some ancient ruins, sprouting in cracks and breaking stones, causing irreparable damage to priceless archaeological structures.

by hand when first identified, physical control is limited because it is almost impossible to dig out all the rhizomes and stolons. Removing rhizomes at the edges of stands, however, will prevent its spread in the immediate area. Disking is discouraged because it will break and spread rhizomes and stolons. Covering the infested area with a plastic sheet for 4–12 weeks may be effective in killing the plants. Chemical control can be achieved with the use of systemics, such as glyphosate. Mowing before application reduces the standing biomass and amount of herbicide required. Potential for biological control includes fungus diseases and insects. The rust fungus (Phakopsora apoda), now established in South Africa, reduces the plant’s ability to photosynthesize but does not kill the plant. A fungus disease caused by Pyricularia grisea kills seedlings. Two insects (Sphenophorus entus vestitus and Herpetogramma licarsicalis) damage plants in Hawai’i. Plants are also susceptible to sugarcane aphids (Sipha spp.).

Selected References “Bermuda Grass.” Blue Planet Biomes, 2002. http://www.blueplanetbiomes.org/bermuda_grass.htm. Fukumoto, Glen K., and Chin N. Lee. “Kikuyugrass for Forage.” Livestock Management, LM-5. Cooperative Extension Service, College of Tropical Agriculture and Human Resources, University of Hawai’i at Manoa, 2003. http://www.ctahr.hawaii.edu/oc/freepubs/pdf/LM-5.pdf. “Kikuyugrass (Pennisetum clandestinum).” Plant Pest and Health Prevention Services (PHHPS), California Department of Food and Agriculture, n.d. http://www.cdfa.ca.gov/phpps/ipc/weedinfo/ pennisetum.htm. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Pennisetum clandestinum (Grass).” ISSG Global Invasive Species Database. 2005. http:// www.issg.org/database/species/ecology.asp?si=183. “Stenotaphrum secundatum (St. Augustine Grass).” ZipcodeZoo, n.d. http://zipcodezoo.com/Plants/S/ Stenotaphrum_secundatum/.

n Medusahead Also known as: Medusahead wildrye Scientific name: Taeniatherum caput-medusae Synonyms: Taeniatherum asperum, T. crinitum, Elymus caput-medusae, Hordeum caputmedusae Family: Grass (Poaceae) Native Range. Western part of the Mediterranean Basin, southern Europe and northern Africa, from Portugal and Morocco east to Turkey and Syria. Possibly native to Southwest Asia as far east as Pakistan.

482 n GRAMINOIDS Distribution in the United States. West Coast, from California north to Washington, east to Idaho, Montana, Nevada, Utah, and Arizona. Also in Nebraska and northeastern states of New York, Connecticut, and Pennsylvania. Description. Medusahead is a winter annual grass with slender stems and leaves. The stems, which branch from the base of the plant, can be either decumbent or erect and reach 8–24 in. (20–60 cm) tall. Each stem has 2–4 short and narrow leaf blades, 1.2–2.5 in. (3–6 cm) long and less than 0.2 in. (5 mm) wide. Leaf margins are somewhat in-rolled and sometimes fringed with hairs. Leaf sheaths are slightly inflated. Both sheaths and leaves may be either glabrous or covered with a downy pubescence of minute hairs. The fibrous roots continue to grow during the cool season, using the upper soil moisture first. Later in the season, they draw moisture from deeper soil layers. If the primary root becomes desAfter accidental introduction into Oregon, medusahead spread iccated, seedlings will survive throughout dry western rangeland and shrub communities. (Native because they are able to grow range adapted from USDA GRIN and selected references. Introduced new roots when moisture again range adapted from USDA PLANTS Database, Invasive Plant Atlas of the becomes available. Plants form a United States, and selected references.) dense mat of stems and roots 1.5–5.0 in. (4–12.5 cm) thick. The inflorescence, which develops in June, is a dense, bristly spike, 0.6–2 in. (1.5–5 cm) long, not including the awns. Spikelets occur in pairs, with two florets each, only one of which is fertile. The lemma of the fertile floret has three veins. Long awns, 1–3 in. (2.5– 7.5 cm), extend from the tips of the lemmas. They are straight or slightly curved when green, but twist and spread erratically as they dry, giving the grass the appearance of the mythical Medusa. Glumes are also awn-like, 0.4–1.6 in. (1–4 cm) long. Both awns and glumes are flat and stiff, with tiny pointed barbs along the margins. When seeds are ripe, spikelets separate from the axis above the glumes, while the axis stays intact. Old flower spikes with the awnlike glumes remain on the plant. Because medusahead matures 2–4 weeks later than perennial native grasses, it is conspicuously yellowish green in pastures of dried native plants.

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A. Medusahead stems branch from the base of the plant. B. When green, the long awns are straight. C. Awns become curved or twisted as they dry. D. Seeds have long awns. (Steve Dewey, Utah State University, Bugwood.org.)

Related or Similar Species. Barley and wildrye are distinguished by having three florets per spikelet and five veins on the lemmas. The flower spike axis breaks apart when seed is mature. Arizona wheatgrass is a closely related California native. Because of the long awns, medusahead may also be confused with foxtail, but the flower spike on that grass also disarticulates when mature. Introduction History. Medusahead was introduced to the United States in the late 1880s, possibly as a seed contaminant. The first collected specimen was near Roseburg, Oregon, in 1887. The plant spread rapidly in the 1930s. Habitat. Medusahead is found in disturbed pasture, sagebrush, chaparral, oak woodlands, agricultural fields, and along dry roadsides. It threatens sparsely populated communities of rangeland, especially those originally dominated by big sagebrush, bluebunch wheatgrass, and Sandberg bluegrass. More complex communities that have been degraded due to overgrazing, fire, or cultivation are also susceptible to medusahead. The grass favors soils with well-developed profiles that have some type of clay horizon. It is likely that a clay layer is necessary to retain water longer, allowing medusahead to mature later in the summer. The species is also found in swales that accumulate runoff. Unlike most perennial grasses, medusahead is adapted to vertisols, which are dry soils that expand and contract when moistened and dried. It is usually not found on well-drained, coarse-textured substrate, or on soils with little profile development. Those areas remain dominated by cheatgrass (see Graminoids, Cheatgrass). Medusahead grows in areas with mild to cold winters and hot summers, but not in places that experience long cold periods. It is found where annual precipitation, falling primarily in autumn, winter, and spring, is 10–40 in. (250–1,000 mm), but most infestations are in sagebrush-bunchgrass communities that receive 10–20 inches (250–500 mm) annually. Reproduction and Dispersal. Flowers are self-pollinated, and reproduction is solely by seed, with 8–15 on each flower spike. Seeds are dispersed locally by wind and water, and carried in coats of livestock, especially sheep, for long distances. New infestations are commonly seen along livestock trails. Seeds remain viable for at least one year. Most seeds germinate in the fall after the first rain, under optimal temperatures of 50–59ºF (10–15ºC), but some germination also takes place in winter and spring. Germination rate is as high as 98 percent, with seeds sprouting within 8–10 hours of being moistened. They do not need

484 n GRAMINOIDS direct contact with soil and germinate best in dense litter with low moisture. They may also emerge from a depth of approximately 3 in. (8 cm). Seedlings grow all winter, and roots grow 7–8 in. (18–20 cm) deep before the plant branches. Roots can be 40 in. (100 cm) deep by February. Plant density can be 100–200 per sq. ft. (1,000–2,000 per m2). Impacts. Medusahead alters the natural plant community and adversely affects the livestock industry. It displaces native grasses and degrades rangeland. The plant changes the shrub and perennial grass community into an annual grass community with less plant diversity for wildlife. Medusahead germinates sooner than bluebunch grass, and plants take water from the same soil depth. In some areas of southwestern Idaho, the grazing capacity of rangelands has been reduced by as much as 80 percent. Because plants contain a lot of silica and are not palatable, medusahead is eaten by livestock only in its early, green stage of growth or when nothing else is available. When dry, the long, sharp awns may injure animals’ mouths and eyes. At any stage of growth, it has little feed value and is not important as wildlife forage, although rabbits may graze the leaf blades. Seeds are indigestible to gamebirds, even to the introduced chukar, which eats cheatgrass seeds. In California and Oregon, where the range and habitat of medusahead overlaps with two introduced bromes, soft brome and cheatgrass, medusahead is displacing cheatgrass on mesic sites. Seeds germinate sooner and faster than cheatgrass and bluebunch wheatgrass. The roots of medusahead seedlings grow faster than those of cheatgrass, tapping soil moisture first, but plants mature 2–3 weeks later than cheatgrass. The thick mat of stems decomposes slowly, tying up nutrients and changing the temperature and moisture regimes in the soil. Although the mat reduces germination of other grasses, such as cheatgrass, it favors germination of medusahead seeds. The thick stem mats increase the fuel load and pose a fire hazard. Management. The best management is prevention, by maintaining healthy native perennial vegetation. Eradicating other invasive plants, especially cheatgrass, can open the ground to medusahead. Most attempts at restoration by reseeding with perennial grasses, such as bluebunch wheatgrass, will not be successful unless medusagrass is first eradicated from the site. A possible first step to reestablishment of native sagebrush-wheatgrass-bluegrass communities, however, is to overseed with squirreltail, a native perennial bunchgrass, which may outcompete medusahead. The self-pollinating squirreltail germinates and matures quickly. It has better root reserves to compete with annuals, is fire tolerant, and has good seed dispersal. Depending on the area, other competitive perennial grasses include intermediate wheatgrass, Thurber’s needlegrass, needle and thread grass, Indian ricegrass, Sandberg bluegrass, and sheep fescue. Physical control targets seed production. Controlled burns conducted in early June, after native grasses have matured but before medusahead seeds set, can almost eliminate medusagrass for several years. A slow, hot burn kills developing seeds, and fires also serve to reduce thatch. Disking or plowing before seed set also reduces seed production. Tillage breaks the thatch and buries seeds too deeply to sprout but also destroys all other plants and alters the soil moisture regime by removing microbiotic crusts. Mowing is also nonselective and fails to crop plants close enough to prevent resprouting. Any mowing after seed set, especially along roadsides, spreads the seeds. Grazing by sheep in the spring when the plant is still in the green stage can control seed production, but animals must be moved before seeds develop to avoid transportation of seeds. Chemical control is limited. Applications of glyphosate and paraquat have provided variable results. Because they are nonselective, they cannot be used where medusahead is mixed with desirable species. Many herbicides used on rangeland target broadleaf weeds

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Does Grazing Cause Medusahead Invasions?

I

n an attempt to assess the impact that grazing has on medusahead invasions, an area of rangeland in Modoc County, northern California, was fenced off from grazing in 1967. The enclosure, which did not have medusahead, was susceptible to invasion because the plant occurred in the surrounding area. Thirty years later, it was discovered that medusahead had successfully invaded and was the dominant herb in both areas. Shrub cover almost doubled in the grazed areas, which logically had fewer perennial grasses, and the non-grazed enclosure had more perennial grasses. However, the only sites in the grazed areas that were totally converted to medusahead were deep vertisol clay soils. A major conclusion was that ecological relations are more complicated and that grazing pressure, or lack of it, is not the only factor than influences medusahead invasion. Source: Wagner, Delmas, and Young, 2001.

and may encourage the growth of annual grasses like medusahead by removing competition. Fall application of atrazine, which targets annual grasses, controls medusahead but may also harm native perennial grasses, such as bluebunch wheatgrass and Columbia needlegrass. Little research has been conducted on biological control. Five soil fungi native to the western United States have been considered, but they are not host-specific and present a danger to winter wheat crops and crested wheatgrass. The near future holds no possibilities.

Selected References Archer, Amy J. “Taeniatherum caput-medusae.” In Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, 2001. http://www.fs.fed.us/database/feis/plants/graminoid/taecap/all.html. Maurer, Teresa, Mary J. Russo, and Audrey Godell. “Element Stewardship Abstract, Taeniatherum caput-medusae.” Global Invasive Species Team, Nature Conservancy, 1988; modified 2009. http:// wiki.bugwood.org/Taeniatherum_caput-medusae. “Medusahead (Taeniatherum caput-medusae).” Plant Pest and Health Prevention Services (PHHPS), California Department of Agriculture, n.d. http://www.cdfa.ca.gov/phpps/ipc/weedinfo/ taeniatherum-caput-medusae.htm. Wagner, Joseph A., Richard E. Delmas, and James A. Young. “Thirty Years of Medusahead: Return to Fly Blown-Flat.” Rangelands 23(3): 6–9, 2001. http://uvalde.tamu.edu/rangel/jun01/wagner.pdf.

n Quackgrass Also known as: Couch grass, dog grass, twitchgrass, creeping wild rye, witchgrass, devils-grass, wiregrass, and others Scientific name: Elymus repens Synonyms: Agropyron repens, Elytrigia repens, E. vaillantiana, Triticum repens, T. vaillantianum, and others Family: Grass (Poaceae) Native Range. Europe, Asia, and Mediterranean North Africa, from the British Isles east to northern India and western China.

486 n GRAMINOIDS Distribution in the United States. Throughout the country except the extreme southeastern states. In Alaska, but not in Hawai’i. Description. Quackgrass is a cool-season perennial with many regional genotypes that give it variable morphology. Erect stems are usually 1–4 ft. (0.3–1.2 m) tall, but decumbent stems, hugging the ground only 0.2–0.8 in. (0.5–2.0 cm) above the soil surface, are more common. The glaucous culms are green to whitish. Leaf blades, 1.5–12 in. (4–30 cm) long and less than 0.5 in. (1.3 cm) wide, are lax and usually droop from the stem. Although becoming flat as they mature, the leaf blades are inrolled when in bud. Leaves are pointed, with a slight constriction at the tip. Small auricles, ear-shaped appendages that occur at the junction of the leaf blade and sheath, are whitish to violet-tinged and clasp the stem. The upper surface of leaf blades is sparsely Quackgrass is found in a wide variety of habitats, but grows best in the hairy, but the lower surface is northern states, with cool climates with long summer days. (Native glabrous. The open sheaths may range adapted from USDA GRIN and selected references. Introduced be either glabrous or softly pubesrange adapted from USDA PLANTS Database, Invasive Plant Atlas of the cent. Hairiness of leaf blades and United States, and selected references.) sheaths is extremely variable, and hairs are usually more noticeable on new spring growth. Ligules are membranous, sometimes with a small fringe. The root system consists of long, somewhat fleshy, slender rhizomes, approximately 0.1 in. (3 mm) in diameter. The many branches of the rhizomes, 4–8 in. (10–20 cm) below the surface, create a tough mat-like network and a loose sod. Rhizomes are pale yellow or straw-colored, with a tough brown sheath at each node that makes the rhizomes appear scaly. Fibrous roots extend from each node. The sharply pointed tips of the rhizomes are able to penetrate hard soils. Quackgrass flowers from May to September. The inflorescence is an erect spike, 2–8 in. (5–20 cm) long, with spikelets in two long rows, alternate on the rachis. Each node on the spike has a single, sessile spikelet, with the spikelets overlapping and flattened toward the stem. Each spikelet has 3–8 florets, each approximately 0.4 in. (1 cm) long. Both the glumes

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A. Stems may be 1–4 ft. (0.3–1.2 m) tall. (Steve Dewey, Utah State University, Bugwood.org.) B. Stems are glaucous and smooth. (Ohio State Weed Lab Archive, The Ohio State University, Bugwood.org.) C. Auricles clasp the stem where the leaf blade joins the sheath. (Ohio State Weed Lab Archive, The Ohio State University, Bugwood.org.) D. Seeds develop on a narrow spike. (Ohio State Weed Lab Archive, The Ohio State University, Bugwood.org.) E. New plants sprout from rhizome nodes. (Steve Dewey, Utah State University, Bugwood.org.)

and the lemmas have either short awns or none. The pale, yellow to brown seeds, which mature from July to September, are elliptical, less than 0.4 in. (1 cm) long. Related or Similar Species. Quackgrass is distinguished from several similar grasses by its solitary spikelets and extensive scaly rhizome system. Blades of rush wheatgrass, hairy wheatgrass, and Russian wheatgrass are stiff and strongly ribbed. Tall wheatgrass and ryegrasses have no rhizomes. Beardless wheatgrass, tall wheatgrass, and crested wheatgrass are all tuftforming grasses without rhizomes. Northern wheatgrass has longer internodes on the spikes. Western wheatgrass leaf blades are strongly ridged and furrowed. Tick quackgrass has pithy culms at anthesis (when anthers and ovules are mature), while quackgrass culms are hollow. Introduction History. First reported in North American in 1672, quackgrass probably arrived as a contaminant in hay or straw. It has since been crossed with other grass species in the development of many hybrids planted for livestock consumption. Its mat of rhizomes makes the plant useful for stabilization of sandy areas or steep slopes, and it can be used for revegetation of mine tailings. Habitat. Quackgrass, found in several types of low-lying moist areas of grassland communities, can colonize both disturbed sites and undisturbed areas. As an early successional plant, it is common in waste areas, along ditches, stream banks, and roadsides, and in cultivated and abandoned fields. It also invades pastures, mixed-grass prairies, open woodlands, and mountain meadows, as high as 9,000 ft. (2,750 m) elevation in Rocky Mountain National Park. Although the grass does best in neutral to slightly alkaline soils (pH 6.5–8.0) that are fertile and loamy, it can grow in a variety of soils, including saline. It does not grow on very acid soils or on rocky outcrops. Quackgrass requires only 90 frost-free days, and grows best when temperatures are 68–77ºF (20–25ºC). Rhizomes grow best in cool temperatures, 50ºF (10ºC), and long, 18-hour days. Rhizomes can survive temperatures as low as 1.4ºF (-17ºC), but surface shoots are killed by frost. Quackgrass is drought tolerant, but does not grow in shade. Reproduction and Dispersal. Quackgrass reproduces both by seed and vegetatively. Although each flower stem may produce as many as 400 seeds, 25–40 is typical. Plants are able to flower and set seed more than once in a season. The wind-pollinated plants require cross-fertilization. Although seeds have no special adaptations for dispersal and most fall

488 n GRAMINOIDS near the parent plant, they are frequently transported in crop seed, straw, or manure. Seeds in the soil remain viable for 2–4 years, and seeds can germinate after passing through an animal’s digestive tract. Seeds germinate in both fall and spring, ideally when diurnal temperatures range from 59º to 77ºF (15–25ºC), and can emerge from a depth of 4 in. (10 cm). Rhizomes begin growth in April and May and grow rapidly in both spring and fall. When the plant sends up new shoots in the fall, as far as 2 ft. (0.6 m) distant from the parent plant, the rhizome also continues to grow horizontally. One plant may have as many as 1,200 dormant buds on its rhizomes, and fragments will grow new plants. Growth of rhizome buds may be stimulated by disturbance. As individual clumps increase in size from rhizome extension each year, they eventually merge to become a continuous stand of quackgrass. Impacts. Quackgrass is an aggressive invader that can grow over 200 new shoots and extend its spread by as much as 10 ft. (3 m) a year. As a cool-season grass, quackgrass begins to grow in early spring, enabling it to outcompete species that begin growth later. By utilizing soil moisture and nutrients, the rhizomes of quackgrass compete with cultivated crops as well as with native grasses and forbs in grassland communities. Because quackgrass dominates disturbed land for several years after invasion, it can alter natural succession, and hinder restoration of damaged areas. It can prevent native woody species from regenerating. Quackgrass infestations increase dramatically after fires, also altering succession. Alleleopathic toxins from the shoots and roots contribute to the ability of plants to suppress native species. In direct contrast to decreasing the biodiversity in an ecosystem, quackgrass also provides cover in grasslands for small rodents, birds, and waterfowl. One of the most difficult invaders to control in cultivated fields, quackgrass can significantly reduce crop yields or reduce productivity of pasture and rangeland. Seeds that contaminate grain crops lower the value of the harvest. Management. Physical control in agricultural fields can be accomplished by tillage and crop rotation, in conjunction with herbicide applications. Although a single effort can increase the infestation by spreading rhizome fragments, two years of intensive cultivation, repeated each time new growth appears, depletes the rhizome reserves. Fields may also be mowed or intensely grazed before tilling, a method that also will reduce reserves. Early spring burns in mixed grasslands, done repeatedly, or burning twice a year have been successful. Chemical control has had mixed results due to various timing of application and lack of repeated attempts. One effective method is application of a postemergent selective to grasses, such as fluazifop, sethoxydim, or clethodim. Infestations in natural areas are more difficult to control with herbicide sprays because of potential damage to nontarget plants. Spot applications or application while native species are dormant is possible. Glyphosate and nicosulfuron are nonselective postemergents. Herbicides should be applied in early spring or fall when quackgrass is 6–8 in. (15–20 cm) tall and actively growing. No biological control is known.

Selected References “Agropyron repens.” Species Abstracts of Highly Disruptive Exotic Plants at Pipestone National Monument. Northern Prairie Wildlife Research Center. U.S. Geological Survey, 2006. http:// www.npwrc.usgs.gov/resource/plants/exoticab/pipeagro.htm.

WEST INDIAN MARSH GRASS n 489 Batcher, Michael S. “Element Stewardship Abstract, Elytrigia repens.” Edited by Mandy Tu and Barry Meyers-Rice. Global Invasive Species Team, Nature Conservancy, 2001. http://www.invasive.org/ weedcd/pdfs/tncweeds/elytrep.pdf. “Quackgrass.” Non-Native Plant Species of Alaska. Alaska Natural Heritage Program. Environment and Natural Resources Institute. University of Alaska, Anchorage, 2006. http://akweeds.uaa.alaska.edu/ pdfs/species_bios_pdfs/Species_bios_ELRE_ed.pdf. “Quackgrass (Elytrigia repens).” Plant Pest and Health Prevention Services (PHHPS), California Department of Food and Agriculture, n.d. http://www.cdfa.ca.gov/phpps/ipc/weedinfo/elytrigia -repens.htm.

n West Indian Marsh Grass Also known as: Water straw grass, trumpet grass, trompetilla Scientific name: Hymenachne amplexicaulis Synonyms: Hymenachne acutigluma, Panicum amplexicaule Family: Grass (Poaceae) Native Range. Tropical Central and South America, from Mexico south to Uruguay, and the West Indies. Distribution in the United States. South of 29º N latitude in central and coastal Florida. Also in Puerto Rico. Not yet reported elsewhere. Description. West Indian marsh grass is a perennial grass, with robust erect culms, or stems, 3.3–8.2 ft. (1–2.5 m) tall and less than 0.5 in. (1.2 cm) in diameter. Stems are glabrous and have few branches. Stems are not hollow, but filled with white pith, called aerenchyma. The large intercellular spaces in the aerenchyma allow oxygen to easily move from the leaves to the roots. The glossy green leaf blades, 4–18 in. (10–45 cm) long and approximately 1.5 in. (4 cm) wide, are flat. Although both the leaf sheaths and blades are generally glabrous, hairs may line the upper margins of the sheaths and the lower margins of the leaves. The leaf sheaths are often spongy. The leaf blade is heart-shaped at the base, with earlike appendages called auricles that clasp the stem. The ligule is membranous. Prostrate stems, or cord-like stolons, extend many feet away from the parent plant. At nodes along the stolons, roots grow to anchor the plant in the substrate. Plants flower September to December, usually with one inflorescence per plant, but sometimes three in succession. The inflorescence is a narrow, spike-like, cylindrical panicle, 4–20 in. (10–50 cm) long and 0.4 in. (1 cm) wide. The short-stalked spikelets, oriented upright on the spike are lance-shaped, compressed, and less than 0.2 in. (5 mm) long, Related or Similar Species. American cupscale, a grass native to the United States, has a similar inflorescence but lacks the white pith in the culms and earlike appendages at the leaf bases. Introduction History. West Indian marsh grass is promoted as forage in seasonally flooded land in the Tropics. Although stems are too coarse to be dried for hay, it can be cut for green feed or for silage. It also can be used as a nutrient sink or sediment trap in polluted areas. It was first described in Florida in 1908, as a rare plant. The first herbarium record is 1957, from a pasture. It may have been intentionally introduced as forage or naturally carried from the Caribbean islands by migrating birds. The second specimen, in 1977, was also from a pasture. Habitat. West Indian marsh grass grows in freshwater wetlands, such as floodplains, swamp margins, and river banks. Adapted to fluctuating water levels, it prefers fertile areas

490 n GRAMINOIDS that are seasonally inundated. It typically grows in water less than 6.5 ft. (2 m) deep, but is sometimes found in water twice that depth. Extensive colonies are especially abundant in sites that are enriched by nutrient runoff, including shallow ponds, cypress swamps, and wet disturbed areas such as pastures, ditches, and drainage canals. The grass needs sunlight and will tolerate only light shade. It is not tolerant of drought or salt, even an occasional tidal impact. Based on its native range and elevation, it may have some adaptations to frost. Reproduction and Dispersal. West Indian marsh grass reproduces both by seed and vegetatively. It is a short-day plant, needing about 12 hours to flower, which may limit its northward spread. Flowering is also stimulated by rainfall, which occurs in autumn in southern Florida. Plants produce a high number of seeds, which are viable for 1–3 years. West Indian marsh grass is a short-day plant that grows in freshwater envi- Seeds are dispersed by stream ronments in Florida. (Native range adapted from USDA GRIN and selected flow, floodwater, and water references. Introduced range adapted from USDA PLANTS Database, birds. Seeds carried by migratInvasive Plant Atlas of the United States, and selected references.) ing birds may account for populations on islands. Nodes on the submerged stolons produce roots and new plants. Pieces of the stolons or entire rafts of plants broken loose from the banks may be carried long distances downstream. New infestations often follow roadsides before spreading into adjacent wetlands because muddy tires of vehicles frequently transport seeds and stolon fragments. Deliberate movement of plants for pasture development also may spread West Indian marsh grass. If plants reach reservoirs, the species can easily follow canals to increase its range. Impacts. Information on the use of West Indian marsh grass as a forage crop indicates that it tends to suppress other species in the habitat, displacing native plants. Everglades National Park, Big Cypress Swamp, and the St. Johns River are at risk. It creates monotypic stands with dense mats both above and below the water, blocking light and developing a large amount of biomass in marsh lands. The grass may alter biodiversity, resulting in fewer

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A. Dense stands of tall West Indian marsh grass can dominate freshwater wetlands. (Chris Gardiner, School of Veterinary and Biomedical Sciences, James Cook University, Queensland, Australia.) B. The base of the leaf blade clasps the stem. (Biosecurity Queensland, Department of Employment, Economic Development and Innovation, Queensland Government, Australia.) C. The inflorescence is a narrow spike. (Chris Gardiner, School of Veterinary and Biomedical Sciences, James Cook University, Queensland, Australia.) D. The lower part of the leaves and upper part of the leaf sheaths are lined with hairs. (Biosecurity Queensland, Department of Employment, Economic Development and Innovation, Queensland Government, Australia.) E. Roots form at nodes along the stolons. (Biosecurity Queensland, Department of Employment, Economic Development and Innovation, Queensland Government, Australia.)

species of native plants and animals. It threatens the survival of riparian forests, where it dominates river banks and prevents normal plant succession. The grass invades habitats needed by several types of native species, including birds, reptiles, amphibians, and fish, reducing the resources available for feeding, shelter, and breeding. Two grasses native to the eastern United States, maidencane and coast cockspur, that provide refuge for wildlife are being displaced by West Indian marsh grass. Habitats for both American alligators and American crocodiles are threatened, as are habitats of wading birds, such as Wood Storks, and raptors, such as the Everglade Snail Kite. By depleting the water of oxygen, stands may kill fish species, including killifishes, live bearers, and juvenile sunfishes. Several native frogs, such as leopard frogs, pig frogs, and green tree frogs are also at risk as their habitat diminishes. Also considered a weed elsewhere in the Tropics, West Indian marsh grass is becoming increasingly difficult to control along drainage canals in Florida. Its dense stands alter water quality and may worsen flooding by changing flow regimes and blocking drainage ways. Management. Eradication of West Indies marsh grass is difficult because it both grows and reproduces quickly. The best management is prevention. Because the plant is a prolific producer of seeds that can be carried long distances, sites should be monitored at least twice a year after any attempt at control. Physical methods must remove the stolons to prevent vegetative regrowth. Mechanical harvesters can be used on small areas as long as root fragments are removed. Because the grass is intolerant of shade, solarization, covering the area with plastic or mulch, may be practical for small areas. Manipulation of water level, either drying out or drowning plants, may facilitate elimination of the grass.

492 n GRAMINOIDS Chemical applications of herbicides can kill buried stolons. Both imazapyr and glyphosate are effective, killing 50–90 percent of plants. Repeated applications are necessary because some plants can recover and produce both stolons and seeds within three months. Burning the stubble after first spraying with glyphosate works well. Treatments should be done prior to flowering to prevent seed development and dispersal. An insect unofficially referred to as the Myakka bug, Ischnodemus variegatus, has potential for biological control. Although native to South America, it was discovered feeding on West Indian marsh grass in Florida in 2000 and now occurs throughout the central and southern parts of the state. The insect can cause severe seasonal damage to West Indian marsh grass by reducing its ability to photosynthesize and slowing its growth rate. It may be hostspecific. Although the grass is susceptible to two fungal diseases, caused by Curvulara lunata and Phyllachora spp., damage is insufficient.

Selected References Diaz, Rodrigo, and Bill Overholt. “West Indian Marsh Grass.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas, Plant Conservation Alliance’s Alien Plant Working Group, 2006. http:// www.nps.gov/plants/alien/fact/hyam1.htm. Diaz, Rodrigo, William A. Overholt, Brent Sellers, and James P. Cuda. “Wetland Weeds: West Indian Marsh Grass (Hymenachne amplexicaulis).” Document ENY-693 (IN491), Institute of Food and Agricultural Sciences (IFAS), University of Florida, 2003; revised 2010.http://edis.ifas.ufl.edu/ in491. “Factsheet—Hymenachne amplexicaulis.” Tropical Forages, n.d. http://www.tropicalforages.info/key/ Forages/Media/Html/Hymenachne_amplexicaulis.htm. Langeland, K. A., H. M. Cherry, C. M. McCormick, and K. A. Craddock Burks, eds. “Hymenachne amplexicaulis (rudge) Nees.” In Identification and Biology of Non-Native Plants in Florida’s Natural Areas, 2nd ed. UF/IFAS Publication #SP 257. Institute of Food and Agricultural Sciences (IFAS), University of Florida, 2008. http://www.fleppc.org/ID_book/Hymenachne%20 amplexicaulis.pdf.

n Shrubs n Asiatic Colubrina Also known as: Latherleaf, common colubrina, Asian snakeroot, Indian snakewood, wild coffee, Asian nakedwood Scientific name: Colubrina asiatica Synonyms: Ceanothus asiaticus, C. capsularis, Celastrus sepiarius, Rhamnus asiatica, R. splendens Family: Buckthorn (Rhamnaceae) Native Range. Coastal East Africa, Madagascar, and the Sechelles; eastern India through Southeast Asia to New Guinea, Solomon Islands, New Caledonia, and northeastern Australia. Distribution in the United States. The frost-free region of the east and west coasts of central and southern Florida, including the Florida Keys and the Everglades, where it has become naturalized. Widespread in the Caribbean and Puerto Rico and probably in the Virgin Islands. Also in Hawai’i. Description. Asiatic colubrina is an evergreen shrub with either drooping or climbing, almost vine-like, reddish-brown slender branches that can be 20 ft. (6 m) or more long. Branchlets are slender and may slightly zigzag between the nodes. Stems on older plants can reach 50 ft. (15 m) and be as thick as 4 in. (10 cm) in diameter. The wood is reddishorange and the bark is dark brown, sometimes with white striations. The thin, papery leaves are oval or egg-shaped, 1.5–5.5 in. (4–14 cm) long and 1–2 in. (2.5–5 cm) wide, with 3–5 distinct raised veins extending from the leaf base. Leaves are alternate on the stem and supported by a short, slender 0.6 in. (1.5 cm) petiole. They are glabrous, shiny dark green on the upper surface and a dull, paler green below. The apex of the leaf is either pointed or slightly notched, and margins are toothed. Leaves produce a thin lather when rubbed with water. Flowering occurs from July to September, and in some places, year-round. Tiny cream to yellow-green flowers, each with five hooded petals surrounding a nectar disk, occur in sparse, branched clusters in the leaf axils. Green and fleshy fruit, pea-size capsules less than 0.5 in. (1.3 cm) in diameter, mature to brownish-red from September to December. Each three-part capsule contains three tiny grayish seeds. Related or Similar Species. Colubrina species native to the United States are all trees or tall shrubs, with erect branches and hairy leaves. Asiatic colubrina can be distinguished by its sprawling habit, glabrous stems and leaves, and leaves with serrated margins. Three species, all rare and endangered, are native to Florida. Coffee colubrina, also known as greenheart, also has shiny leaves but the margins are entire. Twigs are covered with rust-colored hairs, which may also cover the underside of leaves. Cuban nakedwood and soldierwood are similar to coffee colubrina. Introduction History. Asiatic colubrina was intentionally brought to Jamaica in the 1850s by East Asian immigrants, probably for medicinal uses or as a soap substitute. From Jamaica, the plant spread to other Caribbean islands, the Yucatan Peninsula of Mexico, and Florida,

494 n SHRUBS most likely by ocean currents. The earliest records of the species in Florida are in 1937 in the Keys and in the 1950s in the Everglades on the mainland. Habitat. Asiatic colubrina grows on the upland, higher areas of the coast in soils with low permeability, above mean high tide. It can invade either disturbed or undisturbed habitats, including mangrove forests, tidal marshes, beach dunes, and coastal strands. Hammocks of tropical hardwoods and buttonwood are especially vulnerable because they are slightly above flood level. Plants can form thickets along elevated road right-ofways that have been disturbed. Although it is aggressively spreading along the coasts, its northern range may be limited by frost. Reproduction and Dispersal. Asiatic colubrina reproduces both sexually and vegetatively. Although plants can flower and fruit in their first year of growth, few flowers on shrubs of any age Asiatic colubrina occupies habitats above mean tide level in Florida. will produce fruit. The upper (Native range adapted from USDA GRIN and selected references. flowers of each cluster usually Introduced range adapted from USDA PLANTS Database, Invasive Plant abort. Mature seed capsules are Atlas of the United States, and selected references.) dehiscent, sometimes explosively expelling seeds. Little is known regarding germination requirements, other than loose soil and that seeds cannot germinate on exposed rock surfaces. Seedlings need light and will not grow well in the shade of the parent plants. Even so, most seedlings develop in the vicinity of mature plants, and longdistance dispersal is not common. The fruit and seeds, buoyant and salt tolerant, remain viable for many months after floating in salt water and are frequently dispersed by ocean currents and storm tides. Reports of viability of seeds in the soil are conflicting. Seeds may be viable for less than one year or for 3–5 years. Although it is speculated that the pebble-like, hard seeds are ingested by birds for use as crop stones, resulting in another means of longdistance dispersal, no evidence indicates that birds eat the seeds. The ability of Asiatic colubrina to spread vegetatively is tremendous. Roots will develop from any branch that touches the soil. Any damage to the stem stimulates sprouting from the roots and stump. Branches or stem pieces are distributed by storms and extreme tides.

ASIATIC COLUBRINA n 495

A. Plants have long, drooping stems. (Forest and Kim Starr, U.S. Geological Survey, Bugwood.org.) B. Shiny leaves are alternate on the stem. (Forest and Kim Starr, U.S. Geological Survey, Bugwood.org.) C. Leaves have toothed margins. (Forest and Kim Starr, U.S. Geological Survey, Bugwood.org.) D. Fruit are pea-size capsules. (Forest and Kim Starr.) E. Small flowers grow in small clusters from leaf axils. (Forest and Kim Starr.)

Plants grow rapidly. Stems can grow as much as 32 ft. (10 m) in one year, and the species can double its range in 8–10 years. Evidence indicates that Asiatic colubrina recovers from hurricane damage more quickly than do native plant species. Impacts. Considered one of the most aggressive alien weeds in Florida, Asiatic colubrina frequently grows into a thick mat of tangled stems, which can be several feet thick. Climbing plants cover other vegetation with a dense wall of leaves and vines that is almost impenetrable. Stems can grow more than 23 ft. (7 m) to the top of the tree canopy, loop back to the ground and root, and then grow upward again. Plants cover native vegetation, smothering them and shading out native species. Asiatic colubrina even climbs and smothers mature Brazilian peppertree (see Trees, Brazilian Peppertree), another alien species. Because few plants are able to persist under the dense mat, Asiatic colubrina reduces biological diversity. The plant changes the habitat for wildlife and disrupts species interactions. It is especially a problem in Florida’s coastal tropical hardwood forest, which support threatened and endangered plants such as West Indian mahogany, Florida thatch palm, wild cinnamon, machineel, and columnar cactus, as well as bromeliads and orchids. Asiatic colubrina also threatens rare native species, such as bay cedar and beach star in the Florida Keys. Asiatic colubrina’s clambering habit threatens cultural resources, archaeological sites such as Native American middens, hiding them from view and damaging them with their roots. Removal of invasive Australian pine (see Trees, Australian Pine) allows more light to penetrate to ground level, which may increase the growth of Asiatic colubrina. Management. Asiatic colubrina is controlled primarily by physical and chemical methods. Physical removal by hand-pulling is possible for plants which are less than 5 ft. (1.5 m) tall, but only if the roots are small enough to be removed as well. Care must be taken not to disturb the soil, which would encourage germination of any viable seeds in the seed bank. Mechanical methods of removal are generally not practical because Asiatic colubrina is growing on top of and intermixed with other species. If no native species remain, mechanical removal is more efficient. All branches must be carefully removed from the site because the dry fruit is easily dislodged or shattered to spread seeds. Although labor intensive because it is often difficult to find the main trunk among the rambling vines, chemical applications of triclopyr, either to basal bark or to cut stumps,

496 n SHRUBS

Uses of Asiatic Colubrina

S

everal cultures in Southeast Asia, Oceania, and the Caribbean use Asiatic colubrina for medicine and other purposes. Crushed leaves are used as a detergent or shampoo. A leaf extract may be a remedy for centipede stings and other skin irritations. The plant is also used to aid digestion, as a laxative, to expel internal parasites, and to reduce fever. A fruit mixture is used to induce abortions and to kill fish. Leaves are used to weave mats, and the wood is carved for utensils.

are the most effective for adult plants. The cut-stump method is recommended if the stand is fewer than 20 individuals. With more than 20 plants, applications to basal bark are more efficient. If the infestation consists of more than 100 individuals and the vines cover all existing vegetation, triclopyr may be applied to foliage. Because of prolific sprouting from the rooted portion of the plant, monitoring and follow-up applications are necessary. Because of the possibility of viable seeds in the soil, the site should be monitored for several years. Biological control of Asiatic colubrina is difficult because many native species in the buckthorn family, including three endangered species of Colubrina in Florida, may also be susceptible. The long-horn beetle (Artimpaza argenteonota), however, may be host-specific. No microorganisms have been reported to attack Asiatic colubrina.

Selected References Jones, David T. “Asiatic Colubrina.” Plants Gone Wild: Alien Plant Invaders in Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2009. http://www.nps.gov/plants/alien/fact/ pdf/coas1.pdf. McCormick, Cheryl M. “Colubrina Asiatica (Lather Leaf) Management Plan.” Colubrina Task Force. Florida Exotic Pest Plant Council (FLEPPC), 2007. http://www.fleppc.org/Manage_Plans/CA% 20Mngt%20Plan.pdf. Schultz, Gary E. “Element Stewardship Abstract, Colubrina asiatica.” Global Invasive Species Team, Nature Conservancy, 1992; modified 2009. http://wiki.bugwood.org/Colubrina_asiatica. Zheng, Hao, Yun Wu, Jianqing Ding, Denise Binion, Weidong Fu, and Richard Reardon. “Colubrina asiatica, Asiatic Colubrina, Latherleaf.” In Invasive Plants of Asian Origin Established in the US and Their Natural Enemies. U.S. Department of Agriculture, Forest Service, FHTET-2004-05, 2004. http://wiki.bugwood.org/uploads/Colubrina.pdf.

n Brooms Also known as: Scotch broom (Cytisus scoparius), Spanish broom (Spartium junceum), French broom (Genista monspessulana), Portuguese broom (Cytisus striatus) Synonyms: Sarothamnus scoparius, Spartium scoparium, Teline monspessulanus, Genista junceum, Cytisus monspessulanus, and others Family: Pea (Fabaceae) Native Range. Scotch broom is native to most of Europe, and is also from the Canary Islands and the Madeira Islands. Spanish broom is from Mediterranean Europe and North Africa, from Portugal and Morocco east to Turkey, Syria, and the Caucasus region. French broom is native to the Mediterranean regions of Europe and North Africa, from Portugal and Morocco east to

BROOMS n 497

Turkey. Less widespread than Spanish broom, Portuguese broom is native to Portugal, western Spain, and Morocco. Distribution in the United States. Scotch broom grows in the western states, from Montana west to Washington, south to California; and in the midwestern and eastern states, from Wisconsin east to Maine, south to Georgia, west to Alabama, Tennessee, and Kentucky. Both Spanish broom and French broom grow in coastal Washington, Oregon, and California. Spanish broom is also found in Texas. Portuguese broom is in Oregon and California. Description. The taxonomy of brooms is complex. Genera and species are not always well differentiated, and many hybrids occur. Unless otherwise stated, discussion applies to all brooms. Scotch Broom: Scotch broom is a perennial shrub, usually 3– 6 ft. (1–1.8 m) tall, which can reach heights of 12 ft. (3.5 m). Depending on growing conditions, shrubs may have many branches or a single upright Scotch broom is the most common broom in the United States, growing stem. The woody stems are in both the West and in the East. (Native range adapted from USDA five-angled and are star-shaped GRIN and selected references. Introduced range adapted from USDA in cross-section. Branches are PLANTS Database, Invasive Plant Atlas of the United States, and selected green and almost leafless, but references.) new twigs are hairy. The softly hairy compound leaves are small, with three leaflets, each 0.12–0.75 in. (0.3–2 cm) long. Plants are deciduous, without foliage from late summer to early spring. They have a strong, branched taproot and are nitrogen fixing. Flowers appear before the leaves emerge. Bright yellow typical pea-shaped flowers, 0.75–1 in. (2–2.5 cm) long, grow singly or in pairs from the axils of the upper leaves. Greenish-brown to black seed pods, flattened with hairy edges, are 1–2 in. (2.5–5 cm) long. Each pod contains 6–22 yellow-brown, shiny, oblong seeds,—approximately 0.15 in. long and 0.08 in. wide (4 mm by 2 mm). Individual shrubs can live 10–15 years or more. Spanish Broom: Spanish broom, also known as weavers’ broom, is difficult to distinguish from its close relative Scotch broom. Shrubs stand 6–10 ft. (1.8–3 m) tall and are often leafless. Lance-shaped, simple (not compound) leaves 0.5 in. (1.25 cm) long, appear from February to June. Leaves are sparse, and plants are leafless from summer to early spring.

498 n SHRUBS Its green stems, turning brown as they mature, are finely ribbed and round in cross-section. Flowering slightly later than Scotch broom, flowers of Spanish broom are slightly larger, 1 in. (2.5 cm) long, occurring in open racemes at the ends of stems. Seed pods, hairy all over, are 2–4 in. (5–10 cm) long and carry 15 reddish-brown seeds each. Because Spanish broom grows best in full sun with limited water, it is the most droughtresistant species. French Broom: Stems of French broom, also known as Montpelier broom, have 8–10 ridges, are covered with silky silvery hairs, and are round in cross-section. Leafy stems of the evergreen plant are lined with three-part compound leaves. Leaflets, variable in size but usually 0.4–0.8 in. (1–2 cm) long, are waxy above and slightly hairy below. Its flowers occur in clusters of 4–10 on short shoots among the longer stems. French broom Spanish broom is drought resistant and also tolerates salt spray on the is the most aggressive in terms West Coast. (Native range adapted from USDA GRIN and selected of invasion characteristics. references. Introduced range adapted from USDA PLANTS Database, Portuguese Broom: The apInvasive Plant Atlas of the United States, and selected references.) pearance of Portuguese broom, also known as striated broom, is most similar to Scotch broom, but the plants live longer and are larger, as much as 10 ft. (3 m) tall and 20 ft. (6 m) across. Stems have 8–10 sides or angles. Dark-green compound leaves, with 1–3 leaflets, are sparse, with more growing toward the ends of stems. Flowers are pale yellow, and seed pods 0.75–1.75 in. (2–4.5 cm) long, are inflated and covered with white hairs. Related or Similar Species. Bridal broom is distinguished from the others by its white flowers and purple calyxes. It has round pods, each containing only 1–2 seeds, and the pods do not split open as they dry. Gorse (see Shrubs, Gorse), an invasive shrub with a similar appearance and an abundance of yellow pea-shaped flowers, is distinguished by its thorny stems. The native California broom is a smaller plant with both smaller flowers and leaves.

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Introduction History. Scotch broom was introduced to California as an ornamental in the 1850s. Other brooms were also introduced by horticulturalists as garden plants. As early as the 1930s, the U.S. Department of Agriculture Soil Conservation Service introduced and planted brooms for erosion control along roads and to stabilize mine tailings. Habitat. Brooms grow prolifically in disturbed areas, such as roadsides and riverbanks, but may also invade undisturbed land. Plants spread easily to pastures, cultivated fields, dry scrubland, native grasslands, dry riverbeds, and clearings in forests due to logging or fires. They tolerate a wide range of soil types, moisture conditions, and sun or part shade, but cannot grow in deep shade. They grow best in dry, sandy soils and full sun. Plants tolerate light frost but die back under severely cold winters. Scotch broom is found primarily in mountainous and cool coastal areas with dry summers, at elevations as French broom is invasive in more humid regions of the West Coast. high as 5,500 ft. (1,675 m). (Native range adapted from USDA GRIN and selected references. The northern limit of Scotch Introduced range adapted from USDA PLANTS Database, Invasive Plant broom is probably due to cold Atlas of the United States, and selected references.) winter temperatures, while the southern limit is due to summer drought. It rarely grows on limestone. Scotch broom forms pure stands or is mixed with Spanish broom. Spanish broom occupies poor soils, including limestone, and also tolerates salt spray and temperatures as low as 14ºF (−10ºC). It is found below 2,000 ft. (600 m) elevation. French broom is found in more humid and subhumid regions in its native range, and grows below 1,650 ft. (500 m) elevation. Reproduction and Dispersal. Brooms reproduce primarily by seed. Plants produce seeds when they are about 3 ft. (1 m) high and 2–3 years old. They flower from March through June and sometimes again in the fall. Flowers are insect-pollinated, which accounts for crosses between species. Each shrub is capable of producing 2,000–3,500 pods. When pods dry and burst in late summer, during August and September, seeds are forcefully expelled. Seeds are further distributed by water, insects, birds, and other animals, and by human activity such as on boots, vehicles, or equipment. Approximately 50 percent of seeds remain

500 n SHRUBS dormant, and most germinate better after scarification or a cold, moist period of time. Seeds buried deeper than 4 in. (10 cm) in the soil remain dormant. With a hard coat, seeds remain viable for over 30 years under field conditions. Germination begins with fall rains and continues throughout winter until early to midsummer. Seedlings have a high mortality rate during dry summers and are susceptible to browsing by wildlife during the first two years. Plants also sprout from root crowns after cutting or burning. The roots themselves do not produce sprouts. Impacts. Brooms are ideal invaders. Plants grow rapidly, flower young, produce abundant seed that remains viable for years, have a long life span, and also sprout from the root crown. Brooms displace native plants, causing a decrease in biodiversity. Plants outcompete and prevent reestablishment of native trees in forest clearings. Portuguese broom is invasive in California. (Native range adapted from Nutrient dynamics are altered USDA GRIN and selected references. Introduced range adapted from in broom-dominated sites USDA PLANTS Database, Invasive Plant Atlas of the United States, and because the plant is a nitrogen selected references.) fixer. Brooms pose a fire hazard, especially on inaccessible steep slopes, because they are highly flammable and the extensive plant material increases the fuel load. All brooms contain quinolizidine alkaloids, particularly in flowers and seeds, which are toxic to humans, wildlife, and most domestic livestock except goats. Management. Eradication and control is difficult because Scotch broom plants produce abundant seed and also sprout new stems from root crowns. Prevention is critical to controlling brooms. Sites should be monitored after disturbances, and new infestations eliminated. Soil moved from one site to another should be checked for seeds. Even seeds lodged in vehicle tires can spread brooms. Because soil disturbance brings buried seeds close to the surface where they are able to germinate, physical removal that leaves the soil intact is preferred. Hand-pulling or uprooting is practical only on small populations or young plants. Mechanical means can be used on larger infestations. Stripping bark all around the base of the shrub can kill the

BROOMS n 501

A. Small leaves of brooms may be either simple or compound. (Richard Old, XID Services, Inc., Bugwood.org.) B. Stems of Scotch broom are distinctly angled. (Robert Videki, Doronicum Kft., Bugwood.org.) C. Bright yellow pea-shaped flowers cover the bushes. (Utah State University Archive, Utah State University, Bugwood.org.) D. Flattened seed pods of Scotch broom have hairy edges. (Richard Old, XID Services, Inc., Bugwood.org.) E. Seed pods of Portuguese broom are covered with white hairs. (William M. Ciesl, Forest Health Management International, Bugwood.org.)

plant. Regardless of method, plants must be removed below the root crown to prevent resprouting. Because pruning during the wet season will stimulate resprouting, trimming or mowing should be done near the end of the dry season when plants are stressed. Cutting or mowing after flowering may also kill the plants because their nutrient level is low at that time. Cutting or mowing may need to be repeated over several years to deplete the plants’ resources. Removal by burning has had mixed results because fire stimulates germination. Repeated fires on newly germinated plants, however, will help to deplete the seed bank. Flamethrowers can be used for spot treatment. Grazing may be somewhat successful. Although brooms are unpalatable and toxic to most livestock, they are less so when young. Angora goats and Spanish goats eat the tops of young plants, which prevents flowering and seed formation and also eventually depletes the root reserves. Goats have the advantage of being able to negotiate steep slopes where equipment is not practical. Desirable vegetation, however, must be protected from goats. Because their digestive system destroys seeds, chickens can be used to reduce the seed bank. Broom does not do well in deep shade, so planting native trees and shrubs to increase shading may be helpful. Young, actively growing plants are most susceptible to chemical control, best accomplished by spraying the foliage with glyphosate. A triclopyr solution is also effective when painted on cut stumps or applied to basal bark. Biological control is minimal. Although some insects feed on seeds, stems, or leaves of Scotch brooms, they do only minor damage. The twig-mining moth (Leucoptera spartifolilella) from Europe was released in California in 1960 and is now well established. This small white moth lays eggs on new growth, and the larvae tunnel through the stems and emerge the following spring. Affected twigs and branches die, but the effect on the whole plant is unknown. The Scotch broom seed weevil (Apian fuscirostre), also from Europe, is now established in California, Oregon, and Washington. Adults feed on stems, while larvae feed on seeds inside the pods. Although seed production may be reduced by 60 percent, the larvae have little effect on reducing infestations because of the great number of seeds each plant produces. The shoot tip leaf moth (Agonopterix nervosa) from Europe was accidentally introduced in the 1920s. Larvae feed on flower buds and young leaves, decreasing seed production, but control is limited. All three insects are specific to Scotch broom and do not feed on

502 n SHRUBS

Beneficial Uses of Brooms

B

room derives its name from the fact that its stiff branches were used in Europe to make brooms. In its native range in Europe, Spanish broom is used for to make baskets, mats, rope, and paper. A yellow dye is made from its flowers, and an essential oil is used in perfumes. Scotch and Spanish broom flowers are used in Europe for medicinal purposes, including cardiovascular problems, as a diuretic, and to induce labor. No scientific evidence attests to their value, and they are not approved for use in the United States. The plant is useful for erosion control because its deep root structure binds soil.

other brooms. No other insects are currently under consideration in the United States. New Zealand, however, is studying other possible biocontrol agents, including insects and pathogens.

Selected References “Brooms.” Plant Pest and Health Prevention Services (PHPPS), California Department of Food and Agriculture, n.d. http://www.cdfa.ca.gov/phpps/ipc/weedinfo/brooms.htm#anchor384748. “Brooms Cytisus spp., Genista spp., Spartium spp.” Invasive Weeds in Forest Land. Oregon State University, 2008. http://extension.oregonstate.edu/catalog/pdf/ec/ec1598-e.pdf. Nilsen, Erik. “Spartium junceum.” In Invasive Plants of California’s Wildland, edited by Carla C. Bossard, John M. Randall, and Marc C. Hoshovsky. Berkeley: University of California Press, 2000. http://www. cal-ipc.org/ip/management/ipcw/pages/detailreport.cfm@usernumber=79&surveynumber=182.php “Scotch, French, and Spanish Broom, IVM Technical Bulletin.” Noxious Weed Integrated Pest Management Guide, 2000. http://www.ipmaccess.com/Noxbroom.html.

n Exotic Bush Honeysuckles Also known as: Amur honeysuckle (Lonicera maackii), Morrow’s honeysuckle (L. morrowii), Tatarian honeysuckle (L. tatarica), Bell’s honeysuckle (L. x bella) Synonyms: Lonicera insularis, L. sibirica Family: Honeysuckle (Caprifoliaceae) Native Range. Amur honeysuckle is native to east-central Asia, from southern China to Korea and Japan. Morrow’s honeysuckle is native to South Korea and Japan. Tatarian honeysuckle is from central Asia, including southwestern Russia, Kazakhstan, Kyrgyzstan, and western China. Distribution in the United States. Collectively, the four most aggressive species of exotic bush honeysuckle grow in the majority of the country. Distribution of individual species is scattered. Amur honeysuckle is naturalized in the eastern and midwestern states, from New England west to North Dakota, south to Texas, and east to Georgia and the Atlantic seaboard. It is not known in Minnesota, South Dakota, Louisiana, or Florida. Morrow’s honeysuckle is primarily found in the northeastern and Atlantic states, from Maine south to Georgia, and in the midwestern states, from Minnesota to Arkansas. It also grows in the Rocky Mountain region, from Montana south to New Mexico. Tatarian honeysuckle is widespread from the East Coast to the West Coast, with the exception of the extreme south and

EXOTIC BUSH HONEYSUCKLES n 503

the desert states of Nevada and Arizona. It also grows in Alaska. Bell’s honeysuckle grows from Maine south to North Carolina, west to Missouri, and north into the Dakotas. Description. Although five species and one hybrid of exotic bush honeysuckles are known, four species are considered to be the most invasive. Species may be difficult to distinguish. All species are deciduous, upright shrubs reaching 6–20 ft. (1.8–6 m) tall. The glabrous twigs do not have thorns. Bark is light tan, and frequently flaking. Older stems are often hollow, with a brown pith. The opposite dark-green leaves are oval or eggshaped, 1–2.5 in. (2.5–6 cm) on short petioles. Different species may sometimes be distinguished by the amount of hairiness. The paired tubular flowers, less than 1 in. (2.5 cm) long, are showy and grow in leaf axils. Depending on the variety, flowers bloom from May to June and range from creamy white or yellow to pink or crimson. Species also differ in corolla and Found in the eastern half of the United States, Amur honeysuckle is pedicel length. The dark-red to especially adapted to limestone soils. (Native range adapted from USDA orange or occasionally yellow GRIN and selected references. Introduced range adapted from USDA fleshy berries, paired in leaf axils PLANTS Database, Invasive Plant Atlas of the United States, and selected references.) like the flowers, mature from September to October. Berries may remain on the plant during winter, and each berry contains 2–6 small seeds. Growing as tall as 30 ft. (9 m), Amur honeysuckle usually has several stems, with arching branches and stringy tan bark. Its leaves, 1.5–3.5 in. (3.5–9 cm) long, taper to a long pointed tip, and are slightly hairy and pale on the lower surface. The fragrant flowers, 0.75–1 in. (2–2.5 cm) long, are white or pink, fading to yellow. Berries are less than 0.25 in. (6 mm) in size and remain on the plant until mid-winter. Short and broad, usually 5–8 ft. (1.5–2.5 m) tall and 6–10 ft. (2–3 m) wide, Morrow’s honeysuckle becomes a tangled mound of foliage and branches covering the ground. Its gray-green leaves are 1–2.5 in. (3–6 cm) long, wrinkled above and softly pubescent underneath. Flowers, 0.6–0.75 in. (1.5–2 cm) long, are also softly pubescent, supported by

504 n SHRUBS densely hairy peduncles, or short stalk. The white flowers change to yellow as they age. The red berries, which mature June through August, are about 0.25 in. (6 mm) in diameter. Tatarian honeysuckle grows 3.3–12 ft. (1–3.5 m) tall and 10 ft. (3 m) wide. Usually multi-stemmed, the upper branches of the shrub arch into a dense mass of fine twigs. Long flat scales on the bark produce little shredding. The glabrous leaves are 1.25–2.5 in. (3–6 cm) long. The sessile flowers (with no peduncle) are also glabrous, usually pink but varying from red to white. The red, or rarely yellow, berries, 0.25 in. (6 mm), occur singly or in pairs with the bases fused together. Although they ripen from June through August, they remain on the plant in winter. Bell’s honeysuckle, a hybrid between Tatarian honeysuckle and Morrow’s honeysuckle, has intermediate characteristics between the two species and is probably more common than Morrow’s honeysuckle grows in a wide range of habitats, from the Rocky either parent. Difficult to distinMountain states to the East Coast. (Native range adapted from USDA guish, Bell’s honeysuckle has a GRIN and selected references. Introduced range adapted from USDA round growth habit, 4–10 ft. PLANTS Database, Invasive Plant Atlas of the United States, and selected (1.2–3 m) tall, usually with an references.) equal spread. The leaves, slightly hairy on the lower surface, are 1–3 in. (2.5–7.5 cm) long. Because it is a hybrid, Bell’s honeysuckle flower color is variable, usually pink fading to yellow. The red, or rarely yellow, fruit is 0.25–0.5 in. (6–13 mm). Its roots are shallower than those of other exotic bush honeysuckles, less than 6 in. (15 cm) deep, and spreading beyond the crown of the shrub. Other hybrids may exist but may not yet have become established in natural landscapes. Related or Similar Species. Winter honeysuckle, also known as fragrant honeysuckle or sweet breath of spring, and European fly honeysuckle, also known as dwarf honeysuckle, are less invasive species of exotic bush honeysuckles. Winter honeysuckle was introduced to the eastern United States from China in 1945. It is a deciduous or semievergreen shrub, usually 3.2–10 ft. (1–3 m), but sometimes reaching 15 ft. (4.5 m) tall. The plant has an erect and wide-spreading crown of tangled slender branches. Leaves are 0.5–3.5 in. (1.5–9 cm)

EXOTIC BUSH HONEYSUCKLES n 505

long, and paired flowers are 0.5 in. (1.2 cm) long. Berries are less than 0.5 in. (1.3 cm). European fly honeysuckle is a rounded shrub, 3.3–10 ft. (1– 3 m) tall and 10–12 ft. (3– 3.7 m) wide, with spreading arching branches. Several native plants, including honeysuckles, resemble exotic bush honeysuckles. Canadian honeysuckle grows at high elevations and reaches a maximum height of 6.5 ft. (2 m). Red honeysuckle, yellow honeysuckle, and grape honeysuckle are twining vines, not shrubs. Native honeysuckles are also distinguished by their solid stems. Flowers of exotic bush honeysuckles have hairy styles, while flowers of the native species, except for swamp fly-honeysuckle, do not. The fruit of sweetberry honeysuckle and bearberry honeysuckle, also called twinberry honeysuckle, is blue or black. The slender twigs of coralberry are purple to brown, and the leaves of bush honeysuckle are finely toothed and lance-shaped. Tatarian honeysuckle is widespread in the United States, and like all Introduction History. Amur species of exotic bush honeysuckles, grows in disturbed open areas. honeysuckle was brought to (Native range adapted from USDA GRIN and selected references. New York Botanical Gardens in Introduced range adapted from USDA PLANTS Database, Invasive Plant Atlas of the United States, and selected references.) 1898, and by 1931, it was available from at least eight nurseries. Morrow’s honeysuckle was introduced to North America in 1875, and Tatarian honeysuckle arrived as early as 1752. Exotic bush honeysuckles were promoted for wildlife cover and soil erosion control, as well as for ornamental use, and are still sold in both private and state-run plant nurseries. Tatarian honeysuckle has been used for reclamation of mining sites. Habitat. Somewhat intolerant of shade, exotic bush honeysuckles are usually found in open areas, such as abandoned fields, pastures, roadsides, and forest edges. Disturbed sites are common locations. They also invade canopy gaps in woodlands, caused by grazing, windthrow, or insect defoliation. Dense infestations are common beneath bird perches, such as trees, shrubs and fence rows. Amur honeysuckle grows in a wide range of soil types and is especially adapted to calcareous soils. It tolerates wet conditions, such as stream banks that overflow, for short periods of time. It is adapted to cold. Morrow’s honeysuckle, Tatarian

506 n SHRUBS honeysuckle, and Bell’s honeysuckle are found in the widest range of habitats, and also grow in swampy areas, sandy plains, and lakeshores. All three species occupy soils that are poorly drained to well drained, with low nutrient content. Reproduction and Dispersal. Exotic bush honeysuckles reproduce primarily by seed, but will resprout from the roots after the aerial parts are damaged. Bumblebees are the major pollinators, and Bell’s honeysuckle may also be pollinated by hummingbirds. Although information is sparse, exotic bush honeysuckles appear to be prolific in production of berries and seeds. Plants may produce fruit at 3–5 years of age, after reaching 3.3 ft. (1 m) tall. One typical Bell’s honeysuckle in Wisconsin, approximately 6.5 ft. (2 m) tall, produced over 3,500 berries and over 20,000 seeds in one year. In southern Ohio, Amur honeysuckle and European fly honeysuckle may produce 1.2 million berries per plant. Fruit-eating birds, especially American Robins; White-tailed deer; and small mammals, such as deer mice, disperse the seeds. Although most seeds have short-term viability and the soil seed bank appears to be low, some seeds can germinate after 12 years. Little information is available regarding germination requirements, which vary according to species, but some seeds may require a cold dormant period or scarification from passage through an animal’s digestive tract. Because plants are tolerant of only moderate shade, more germination takes place in sunny sites. Establishment is best where litter cover is sparse and few herbaceous plants offer competition. Cultivated land can be a barrier to the advance of exotic bush honeysuckles, while forested areas, which provide habitat for birds which disperse seeds, can promote its spread. Impacts. By aggressively creating a dense shrub layer, exotic bush honeysuckles shade and crowd out native plants. They have a competitive advantage because they leaf out earlier in spring and retain leaves later in the fall. They alter the habitat by decreasing light and depleting soil moisture and nutrients. Plants may also be alleleopathic. Exotic bush honeysuckle infestations restrict the growth of native plant seedlings and annual herbs, thereby affecting natural biodiversity and interfering with succession in forest habitats. They may also compete with native honeysuckles for pollinators, resulting in reduced seed production from natives. Although the fruit is rich in carbohydrates, it supplies too little of the fat and nutrients required by migrating birds. Berries of Amur honeysuckle are mildly poisonous. Birds, particularly American Robins, that use exotic bush honeysuckles for nesting sites may lose more eggs and young to predation due to the lack of protection afforded by the thornless branches. Management. Control or eradication of exotic bush honeysuckles requires a commitment of 3–5 years. While it may be impossible to restore highly infested areas to a natural state, it can be accomplished in newly infested areas. Sites with bare soil are susceptible to invasion and must be monitored for seedlings. Physical removal of seedlings and small shrubs is possible by pulling or digging, but soil disturbance will promote seedling growth. Any root not removed may resprout. Repeated clipping or trimming of branches may prevent dense stands from forming. Clipping in winter, however, will encourage vigorous resprouting. All plant parts, especially fruit, must be bagged and properly disposed. Prescribed annual burns will kill the top of shrubs and limit regrowth. Burning should be done at least every other year, before seeds are dispersed, for several years. Chemical application of glyphosate or triclopyr is frequently necessary. Foliar sprays are appropriate where no risk to nontarget plants exists, such as in large monospecific thickets. If grasses are present, the broadleaf selective triclopyr should be used. Individual shrubs can be cut and the stumps treated with either glyphosate or triclopyr, but triclopyr or imazapyr is best for basal bark applications. A flush of seedlings may follow herbicide treatments, but can themselves be treated.

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What Method Works Best?

I

n a scientific study of the effects of Amur honeysuckle (Lonicera maackii), Sahar Haghighat, a biology student at Monmouth College, concluded that the best method for increasing the biodiversity of understory plants where Amur honeysuckle has invaded is to physically uproot and remove entire plants, including the root system. Working with the hypothesis that management or elimination of Amur honeysuckle would increase the understory biodiversity, she compared three management methods to ascertain their effects. She outlined three experimental plots and one control plot, each 10 x 10 m2, with a buffer zone in between to ensure that the control treatments were completely separate. Plots were in the forested areas of LeSueur Nature Preserve in Monmouth, Illinois, which is a restored prairie with prairie grasses and typical midwestern trees. Plot 1 was the control, where nothing was done. In Plot 2, all Amur honeysuckle stems were clipped or trimmed, to reduce their shading effect, to 30 cm above the ground. In Plot 3, the same amount of clipping was combined with application of herbicide, a 50 percent concentration of glyphosate isopropylamine salt solution, painted on rather than sprayed to prevent damage to surrounding plants. In Plot 4, plants were totally removed, including all roots, by digging out or uprooting. Beginning in early summer 2008 and ending in summer 2009, each plot was sampled five times, recording species abundance and growth stage. Analysis included a calculation of importance levels of each species. While Amur honeysuckle was of course the most important species in the plots, its values dropped over the course of the project. Other plants, primarily opportunistic nonnative invaders such as garlic mustard (Alliaria petiolata) increased in abundance in the treated plots. Although all four plots were similar at the start of the project, they became increasingly different in terms of species composition as the project progressed, indicating that Amur honeysuckle was indeed responsible for the low biodiversity in sites where it dominated. While all treatments were followed by an increase in biodiversity, total removal of the Amur honeysuckle plants resulted in the biggest change. The most significant increase in biodiversity and biggest difference from the control plot was in the experimental plot where Amur honeysuckle plants were uprooted. Although results may be different with a greater number of samples or other refinements of methodology, the conclusion of this simple but well-done study was that physical removal of Amur honeysuckle by uprooting, while initially the most difficult and time-consuming, is the best method to restore biodiversity of the understory in wooded areas.

Source: Summarized from “Response of Lonicera maackii to Different Removal Methods and the Ecological Effect upon Native Species,” by Sahar Haghighat, Department of Biology, Monmouth College, Monmouth, IL, 61462, USA, May 12, 2010.

Because exotic bush honeysuckles appear to be free of diseases, insects, and predators, no biological control is available. An aphid (Hyadaphis tatariacae) feeds on the tips and shoots of Tatarian honeysuckle, and possibly on Morrow’s honeysuckle and Bell’s honeysuckle. The resulting “witch’s broom” tuft of twigs may interfere with flowering. Any potential

508 n SHRUBS organisms, however, must be host-specific to ensure that native honeysuckle species are not affected.

Selected References Batcher, Michael S., and Shelly A. Stiles. “Element Stewardship Abstract for the Bush Honeysuckles.” Global Invasives Team, Nature Conservancy, 2000. http://www.invasive.org/weedcd/pdfs/ tncweeds/loni_sp.pdf. “Bush Honeysuckles.” Southeast Exotic Pest Plant Council (SEEPPC) Invasive Plant Manual, 2003. http://wiki.bugwood.org/Archive:SEEPPC/Bush_Honeysuckles_-_Lonicera_spp. Munger, Gregory T. “Lonicera spp.” In: Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, 2005. http://www.fs .fed.us/database/feis/plants/shrub/lonspp/all.html. Williams, Charles E. “Exotic Bush Honeysuckles.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2005. http://www.nps.gov/ plants/alien/fact/pdf/loni1.pdf.

n Gorse Also known as: Common gorse, furze, Irish furze, whin Scientific name: Ulex europaeus Synonyms: None Family: Pea (Fabaceae) Native Range. Central and western Europe and the British Isles, where it is not aggressive and is cultivated as hedgerows to enclose livestock. Distribution in the United States. Pacific Coast, from California, north to Washington. Scattered in southern California as well as on the Atlantic coast, from Massachusetts south to North Carolina, where it is not an aggressive invader. Also in Hawai’i. Description. Gorse is a very prickly evergreen shrub, usually growing 1.5–10 ft. (0.5–3 m) tall, but occasionally reaching 16 ft. (5 m). The woody shrub branches densely from the base of the plant. The stout branches are longitudinally ridged. Young green twigs are covered with gray to reddish-brown hairs, while older branches turn brown and become stiff, intertwined, and thornlike. Young plants are mat-like in form, but as plants age, they tend to grow outward, forming a ring of growing vegetation around a dry, dead center. One plant may be as large as 30 ft. (9 m) in diameter. Under sustained windy conditions, plants may be sculpted into cushion or mat forms. Individual plants live for about 30 years. Gorse has different types of leaves according to the age of the plant. Seedlings grow in a compact rosette-leaf pattern. Juvenile plants, usually up to 2–4 in. (5–10 cm) tall, have compound leaves typical of the pea family, with three leaflets. Leaves on larger plants are alternate and reduced to awl-like stiff spines. Branches may appear leafless because of the reduced leaf structure. Branches and twigs terminate in a bottle brush of spiny leaves 0.5–2 in. (1.3–5 cm) long. Gorse has two types of roots, a fibrous system of lateral roots in the top few inches of soil and a deeper taproot. Bloom season varies with latitude, but generally occurs from March through May. In Hawai’i, flowering begins in December. Inflorescences, containing either single flowers or small clusters, grow in leaf axils and near the ends of twigs. One plant may have thousands of flowers, which completely cover the bush. Shiny, bright yellow flowers are distinctly pea

GORSE n 509

like, with a two-lipped corolla. Flowers are 0.8–1 in. (2– 2.5 cm) long, and the calyx is densely covered with soft hairs. Fragrant flowers attract pollinators, and seed pods mature about two months later. The fruit is a very hairy pod, 0.5–1 in. (1.3–2.5 cm) long, usually containing 2–6 hard olivebrown kidney shaped seeds. A fleshy, yellow protrusion on one end of the seeds is rich in oil and protein. Related or Similar Species. Gorse may be confused with one of the brooms, such as Scotch broom (see Shrubs, Brooms), which are also invasive species, but those plants have no spines. Gorse also forms denser, more impenetrable thickets. Dwarf gorse, reaching only 10 in. (30 cm) tall, is native to eastern England and western France, Spain, and Portugal. It has smaller flowers and softer spines, and is not naturalized in the United States. Introduction History. Gorse was probably brought to the East Coast by immigrants, who Although present on both coasts, gorse is invasive only in the West. used the plant extensively in (Native range adapted from USDA GRIN and selected references. Europe, including for animal Introduced range adapted from USDA PLANTS Database, Invasive Plant fodder and as a yellow dye. Atlas of the United States, and selected references.) Gorse was introduced to the West Coast, possibly to Mendocino County, California, or to Oregon, prior to 1894. By the 1950s, it had spread to western Washington, western Oregon, and northern California, with localized infestations on 15,000 ac. (6,000 ha) in California and on 25,000 ac. (10,000 ha) in Oregon. Gorse was introduced to Hawai’i as a hedge plant and ornamental sometime before 1910. Habitat. Gorse most frequently invades disturbed sites and can be found growing on sand dunes, gravel bars, overgrazed pastures, logged areas, and burned sites. It can also occupy forests, riparian sites, coastal scrub, and coastal cliffs. Because gorse is a nitrogen fixer, it is capable of growing on infertile soils and most every soil type, including silty, rocky, and clay. It can grow on serpentine soils, occasionally on calcareous sites, and can colonize barren mine dumps. Tolerant of acidity, it prefers a pH of 4.5–5.0, but also requires trace elements, such as boron, to grow well. It grows best in shady exposures but is

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A. Gorse is a densely branched woody shrub. (Forest and Kim Starr, U.S. Geological Survey, Bugwood.org.) B. Leaves on large stems are reduced to stiff spines. (George Markham, USDA Forest Service, Bugwood.org.) C. The hairy seed pods contain hard seeds. (Forest and Kim Starr, U.S. Geological Survey, Bugwood.org.) D. Pea-shaped flowers grow in showy spikes. (Forest and Kim Starr, U.S. Geological Survey, Bugwood.org.)

intolerant of heavy shade. Gorse requires moist, but well-drained, soils because the nitrogen-fixing bacteria are rendered ineffective under flooded conditions. Gorse requires a temperate climate and cannot tolerate drought. Its sensitivity to extremes of heat and cold limits its spread away from the coast. Its latitudinal range may be limited by photoperiod. Short summer days limit both flowering and thorn formation. Reproduction and Dispersal. Although gorse reproduces both vegetatively and sexually, it spreads predominantly by seed, and is a prolific seed producer. Plants can produce 14 million seeds per ac. (35 million per ha) each year. The upper inch (2.5 cm) of soil may contain 2,000 seeds per sq. ft. (20,000 per m2). Pods are explosively dehiscent, opening forcefully when dry and ejecting the seeds 3.3–10 ft. (1–3 m) from the parent plant. Although small, seeds are too heavy to be carried by wind, but are dispersed by water, ants, ground birds such as quail, other animals, and human activity. Improperly dumped garden waste, hikers, machinery, vehicles, and fill dirt may also be responsible for seed distribution. Because the seed coat is very hard and impenetrable by water, seeds are viable for 30–50 years. Seeds usually germinate in the wetter winter and spring months, but germination may occur any time of year if conditions are suitable. Germination increases substantially, either due to more light or higher soil temperatures, when mature plant cover is removed. Heat, particularly from fires, stimulates germination, but temperatures above 212ºF (100ºC) are lethal to seeds. Plants need a minimum of 18 months to grow from a seedling to reproductive age. Plants also vigorously resprout from stumps. Stems touching the ground will root, and some evidence suggests that gorse also spreads by creeping rhizomes. Impacts. Although initially slow to spread, gorse impacts the environment in a variety of ways. It forms dense, spiny thickets that remain impenetrable even when plants are dead. It outcompetes both native and cultivated plants, in part due to its nitrogen-fixing bacteria, which allow it to colonize soils that are poor in nitrogen. Nitrogen can accumulate at 20–30 pounds per ac. (22–34 kg per ha) every year. Gorse leaf litter makes the soil more acid and less suitable for native species. By replacing grassland, gorse thickets result in a loss of valuable pasture. By displacing native plants, it also decreases native wildlife habitat. In Hawai’i, where gorse occupies approximately 35,000 acres (14,000 ha) on both the island of Hawai’i and Mau’i, it threatens mamane forests and native birds, such as the palila.

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Because plants grow rapidly, a lot of dry plant litter accumulates. A new stand can accumulate 5,500 lb. per acre (6,000 kg per ha) of dry material in its first year. Dry matter accumulation in older stands can be 90–180 lb. per acre (100–200 kg per ha) every year. The oils in the foliage and litter are highly flammable, not only making gorse an extreme fire hazard but also causing fires to burn hotter. Gorse produces abundant pollen, and the major pollinator is the honey bee, making the plant attractive to commercial beekeepers. Management. The most effective control for gorse is rapid response, eliminating the shrub when it first invades. In order to be effective, management efforts must be long term because of the longevity of viable seeds. Preventing seed production is an option, and Hawai’i has tried restricting commercial bee keepers from setting hives near gorse. Reseeding with native plants should follow methods of control or eradication. Because gorse is intolerant of shade, it may be suppressed by taller plants. Research in both chemical and biological control is being conducted in Australia and New Zealand where gorse is also seriously invasive. The spiny nature of gorse makes it difficult to remove by physical means. Young plants, less than two years old and under 5 ft. (1.5 m) tall, may be removed by hand-pulling or digging, but all root pieces must be removed. Repeated cutting of aerial parts may deplete nutrient stores in roots, especially if done when reserves are lowest, just as plants begin to flower. In spite of the fact that burning will not remove either the roots or the seed bank in the soil, fires are most efficient in removing large plants. Although fire will kill seeds in the top 0.4–0.8 in. (1–2 cm) of soil, the deeper ones are stimulated to germinate. Repeated burning, however, may reduce the seed bank. Physical removal of the upper part of the shrub, down to the stumps, may be necessary to gain access to the base of the plant for herbicide application. Cutting or burning will also reduce seed production. Any physical removal of the top portion of plants should be followed by herbicide application to prevent resprouting. Grazing, particularly by angora goats, can control seedling and resprouts, but mature plants are too woody and spiny to be palatable to herbivores. A minimum of two years of grazing of new growth is needed to show any reduction in gorse. The digestive system in chickens destroys many weed seeds, including gorse, making chickens effective at reducing the seed bank. A number of herbicides, such as dicamba, triclopyr, 2,4-D + triclopyr, picloram, tordon and glyphosate, may provide chemical control of gorse. Some types, however, are not effective on mature plants because of the structure of the spiny leaves and their waxy cuticle, which prevents absorption of the herbicide. Seedlings are effectively eliminated by picloram, glyphosate, or triclopyr. Cut stumps of mature plants are best treated with glyphosate. Because different herbicides have different effects on nontarget species, the choice of which to apply depends on what remaining native vegetation must be protected. Regardless of the herbicide used, treatments must be repeated. No biological means of control are totally effective at controlling or eradicating gorse. The gorse weevil (Apion ulicis), from France, is established in California and Oregon. The larvae feeds on seeds inside the pod. When the pods ripen and open, the adults emerge to eat spines and flowers. Effects are limited in cool coastal climates because the adult weevils die inside the pod before the pods ripen and burst. The gorse spider mite (Tetranychus lintearis), introduced to and established in Hawai’i, damages plants but does not reduce populations. Colonies of the spider mites weave a tent-like web on the gorse plants and eat leaves of the mature plant. Effectiveness of other insects now established in Hawai’i, such as a foliage-eating moth (Pempelia genistella) and gorse thrips (Sericothrips staphylinus), is not yet known.

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Selected References Hoshovksy, Marc. “Element Stewardship Abstract, Ulex europaeus.” Global Invasive Species Team, Nature Conservancy, 1989; updated 2001. http://www.imapinvasives.org/GIST/ESA/esapages/doc umnts/ulexeur.pdf. Markin, George. “Ulex europaeus L., Common Gorse.” In The Woody Plant Seed Manual, Agricultural Handbook No. 727, edited by Franklin T. Bonner and Robert P. Karrfalt. U.S. Department of Agriculture, Forest Service, 2008. http://www.fs.fed.us/rm/pubs_other/wo_AgricHandbook727/ wo_AgricHandbook727_1140_1142.pdf. Motooka, P., et al. “Ulex europaeus.” In Weeds of Hawai’i’s Pastures and Natural Areas: An Identification and Management Guide. College of Tropical Agriculture and Human Resources, University of Hawai’i at Manoa, 2003. http://www.ctahr.hawaii.edu/invweed/WeedsHI/W_Ulex_europaeus.pdf. “Ulex europaeus.” Pacific Island Ecosystems at Risk (PIER). Hawaiian Ecosystems at Risk (HEAR), n.d. http://www.hear.org/pier/species/ulex_europaeus.htm.

n Japanese Barberry Also known as: No other names Scientific name: Berberis thunbergii Synonyms: Berberis thunbergia var. atropurpurea, Berberis sinensis, Berberis japonica Family: Barberry (Berberidaceae) Native Range. Japan Distribution in the United States. Eastern half of the United States, from Georgia north to New England, west to the Great Plains states, and from North Dakota south to Nebraska. Also in Wyoming and Washington. Description. Japanese barberry is a compact and spiny deciduous or semievergreen shrub with many branches. It usually grows 2–3 ft. (0.6–0.9 m) tall, but occasionally reaches 8.2 ft. (2.5 m). The deeply grooved brown branches form slight zigzags, rather than growing straight. Plants are hairless, but have one very sharp, simple spine in each leaf axil. The inner bark and wood is yellow. Leaves grow in tight, alternate bunches close to the branches. They are spoon-shaped or narrowly oval and wedge-shaped at the base. Leaves have smooth margins and vary in size, 0.5–1.5 in. (1.3–4 cm) long. Plants are distinguishable by the leaf color, ranging from bright green to burgundy. In warmer southern climates, plants may retain leaves during the winter. The root system is shallow, but tough. An abundant number of small pale-yellow flowers, 0.3–0.4 in. (8–10 mm) long, appear from March to May, depending on geography. Clusters of 2–4 flowers hang in small umbels along the entire stems of the shrub. The small, oblong fruits are bright red berries, approximately 0.3 in. (8 mm) in size, maturing from July through October. Although slightly juicy, they are solid. The clustered berries remain on the stems until spring. Related or Similar Species. Common barberry, a nonnative plant from Europe and western Asia, was formerly used extensively by early settlers for hedgerows, dye, and jam. However, because it was host to the black stem grain rust transmitted by the fungus Puccinia graminis, grain crops were devastated. Beginning in 1916, steps were taken to eradicate common barberry. Berberis x ottawensis is a hybrid of common barberry and Japanese barberry. American barberry, the only barberry native to North America, is found in dry woodland. It can be distinguished by its sharply toothed leaves and three-prong spines. Introduction History. Japanese barberry was introduced to the United States as an ornamental plant in 1875, when seeds from Russia were sent to Arnold Arboretum in Boston. In 1896, it was planted at the New York Botanical Garden and recommended as a substitute for the

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common barberry because it is not a host for the black stem grain rust. In 1910, Japanese barberry became naturalized in the Northeast after it escaped cultivation from plantings at vacation home sites. It is still a popular landscape plant, with several cultivars sold in nurseries. Habitat. Although it first colonizes open fields and pastures, Japanese barberry grows in a variety of habitats, including roadsides, railroad and utility right-of-ways, and fencelines. It grows best with at least part sun, but because it is shade tolerant, it can form dense stands in several types of forest, such as floodplain, planted, and successional. It is less common, however, in forests dominated by oaks or on north-facing slopes. Well-drained sites are preferred, but it also occupies wetlands. Japanese barberry does not compete well with grasses. Severe drought or extremely cold winters do not negatively impact either plants or seed production. Deer generally avoid Japanese barberry but browse other veg- Imported as a substitute for common barberry, Japanese Barberry is etation, giving the invaders more prominent in the northern Great Plains and eastern states. (Native range adapted from USDA GRIN and selected references. Introduced range room to spread. Reproduction and Dispersal. adapted from USDA PLANTS Database, Invasive Plant Atlas of the United States, and selected references.) Japanese barberry reproduces both sexually and vegetatively. Plants are prolific seed producers, and the germination rate is as high as 90 percent. Birds, most often ground birds such as Wild Turkey, Bobwhite Quail, Ring-necked Pheasant, and Ruffed Grouse, eat the fruit and deposit seeds elsewhere. Other birds drop seeds when they rest on power lines or on trees at forest edges or roadsides. Small mammals, such as rabbits, also eat the fruit and distribute seeds. Plants sprout from rhizomes, and branches will root when in contact with moist soil. Impacts. Japanese barberry plants can form dense, continuous stands that threaten natural areas by displacing native plants and reducing habitat and forage for native birds and mammals. Because it is one of the first plants to produce leaves in spring, it shades out native understory plants. Growth can be rapid, especially for seedlings, as much as 2–4 ft. (0.6– 1.2 m) in one year. Shrubs also change soil chemistry, altering nitrogen content and

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A. Shrubs are compact and spiny. (Richard Old, XID Services, Inc., Bugwood.org.) B. Twigs slightly zigzag, with a sharp spine in each leaf axil. (James H. Miller, USDA Forest Service, Bugwood.org.) C. Spoon-shaped leaves may remain on the plant in warmer climates. (James H. Miller, USDA Forest Service, Bugwood.org.) D. The oblong fruit are bright red berries. (Richard Old, XID Services, Inc., Bugwood.org.) E. Flowers hang in short clusters. (Leslie J. Mehrhoff, Ecology and Evolutionary Biology, University of Connecticut, Bugwood.org.)

biological activity in the soil. The species raises the soil pH and, by retaining its leaves, may reduce the depth of litter where it is semievergreen. Management. Because Japanese barberry seeds are abundant and dispersed easily, reducing seed production should be a priority in control. Whatever type of physical control is used to eliminate Japanese barberry, care should be taken to minimize soil disturbance. Plants are easy to pull out of forest soils in early spring, an option that is feasible only if numbers are low. Hand-pulling or digging out whole plants is effective when plants are less than 3 ft. (0.9 m) tall. All connected roots must be removed and remains properly disposed of to prevent accidental dispersal of seed. Uprooting plants, which can be done any time of year, reduces both the population and seed development. Plants are easier to see in winter, however, when native species are leafless. Mowing or cutting, as short as possible, effectively controls the spread of Japanese barberry by reducing flower and seed development, but will not kill plants. Mowing should be done at least once each growing season. Fire kills Japanese barberry and is a good option, but only in fire-adapted communities. Because of detrimental effects on nontarget native plant species, chemical applications should be used only on plants that are difficult to remove by hand. Foliar sprays, such as glyphosate and triclopyr, are effective when temperatures are above 65ºF (18ºC). Both herbicides can also be used on cut stumps, a more selective method than spraying, any time the soil is not frozen. No biological controls are available.

Selected References “Japanese Barberry.” Invasive Plant Atlas of New England (IPANE). University of Connecticut, 2009. http://nbii-nin.ciesin.columbia.edu/ipane/icat/browse.do?specieId==26. “Japanese Barberry.” Southeast Exotic Pest Plant Council (SEEPPC) Invasive Plant Manual, 2003. http://www.invasive.org/eastern/eppc/barberry.html. “Japanese Barberry.” Weed of the Week. U.S. Department of Agriculture, Forest Service, Invasive Plants, 2005. http://www.na.fs.fed.us/fhp/invasive_plants.

KOSTER’S CURSE n 515 Miller, Arthur E. “Black Stem Rust Quarantine.” Invasive Plants of the Eastern U.S., 2003. http://www .invasive.org/eastern/other/barberry.html. Swearingen, Jil M. “Japanese Barberry.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2009. http://www.nps.gov/plants/ALIEN/fact/ beth1.htm.

n Koster’s Curse Also known as: Soapbush, clidemia, camasey, nigua Scientific name: Clidemia hirta Synonyms: Melastoma hirta, Clidemia crenata, M. elegans, C. Elegans, M. hirtum Family: Melastome (Melastomataceae) Native Range. Tropical Central America and South America, from Mexico to Paraguay and northern Argentina. Also in the Greater and Lesser Antilles in the Caribbean, including Puerto Rico and the Virgin Islands. Distribution in the United States. Hawai’i. Description. Koster’s curse is a branched perennial shrub, either scrambling or growing upright. Branches and twigs are round and slender, and the plant is covered with straight red bristles or hairs that become lighter with age. When many stems arise from one rootstock, the shrub can become very dense. Depending on habitat conditions, mature shrubs may be 3.3–16.5 ft. (1–5 m) tall, shorter in exposed sites and taller in moist, shady locations. The oval leaves, 2–7 in. (5–18 cm) long and 1–3 in. (3–8 cm) wide, are opposite on the stem and grow on short petioles, 0.2–1.2 in. (0.5–3 cm) long. Each leaf has 5–7 prominent veins running from the base to the pointed tip. Many lateral veins intersect the longer veins, making the leaf appear checkered or pleated like seersucker fabric. Leaves are slightly hairy, and leaf margins are smooth or slightly scalloped or serrated. During dry seasons, the plant may lose its leaves, but will generate new leaves when adequate rain falls. Plants have a shallow lateral root system with many fine rootlets. Small white flowers, each with five petals, grow in short panicles, approximately 1 in. (2.5 cm) long, both at the ends of branches and in leaf axils. The calyx is hairy. Purple to black, fleshy berries, 0.3 in. (7 mm) in diameter and covered with bristles, taste a bit like blueberries. Each four-celled berry contains 100 or more very small coffee-colored seeds. Related or Similar Species. Other members of the Melastome family present in Hawai’i include velvet tree (see Trees, Velvet Tree) and two Tobouchina species, cane ti and glorybush, all native to tropical South America. Velvet tree is a branching plant, as tall as 45 ft. (13.5 m), with large, velvety leaves. Its leaves are as long as 3 ft. (1 m), green on the upper surface and purple below. Its upright inflorescences of tan flowers are not showy. Both Tobouchina species are smaller shrubs. Cane ti reaches 9 ft. (2.5 m) tall, with smaller leaves, 3 in. (7.5 cm) long. Its flowers are pink, with four petals and bright yellow anthers. Because it does not spread by seeds, glorybush is a less invasive plant. It grows to 12 ft. (3.5 m) tall, with 5 in. (12.5 cm) long leaves, and five-petaled purple flowers. Bristletips, native to the Himalayas and southwestern China, is also a smaller shrub 6.5–13 ft. (2–4 m) tall, with pendulous branches. Its leaves, 3–6 in. (8–16 cm) long, have only five parallel veins, and its pinkish-purple flowers grow in drooping clusters. Introduction History. In the 1880s, a man named Koster imported coffee plants from Central or South America to develop a plantation in Fiji and accidentally introduced Clidemia seeds. The plant quickly spread from Fiji to other Pacific Islands and became known as Koster’s curse because of its invasive properties. Although the date it reached Hawai’i is

516 n SHRUBS unknown, it was first recorded on O’ahu in 1941. It may have been an intentional introduction through the horticulture trade or as a specimen in a botanical garden or zoo. The tiny seeds could also have been a contaminant and brought to the island accidentally. By 1957, it was recognized as a noxious plant, and by 1988, it covered approximately 247,100 ac. (100,000 ha) on O’ahu alone. Plants are found on almost all the major islands, and it is still expanding its range. Habitat. Even in its native range, Koster’s curse spreads most rapidly in disturbed soil, including floodplains, pastures, agricultural fields, and roadsides. It rarely occurs in forests in its native range and appears to be more tolerant of shade in locations to which it has been introduced. The plant grows in a wide range of soil types, but needs moisture. Rainfall in its native range, where it grows from sea level to 5,000 ft. (1,500 m) elevation, is 47–157 in. (1,200–4,000 mm). It, thereKoster’s curse is primarily an invader of disturbed sites in Hawai’i. (Native fore, has the potential to invade range adapted from USDA GRIN and selected references. Introduced all wet and mesic habitats range adapted from USDA PLANTS Database, Invasive Plant Atlas of the below 5,000 ft. (1,500 m) United States, and selected references.) elevation, and may extend even higher. Although it grows best in full sun, it is tolerant of shade and can grow in both open and closed habitats, even with 100 percent canopy cover, under both native and introduced trees. Koster’s curse is primarily a weed on disturbed sites, where gaps, caused by storms, feral pigs (see Volume 1, Vertebrates, Mammals, Feral pig), landslides, and fire, occur in the forest subcanopy. Infestations are especially linked to disturbances by feral pigs. The shrub can also invade undisturbed areas, but its populations remain low. Reproduction and Dispersal. Koster’s curse reproduces both by seed and vegetatively. Where conditions are continually moist, Koster’s curse will flower and fruit year-round. It is a prolific seed producer. A large plant can produce more than 500 fruit each year, each containing 100 seeds, for a total of 50,000 seeds annually. Seeds are dispersed in several ways. Many seeds are distributed locally by nonnative species, such as birds, feral pigs, and mongooses, as well as by humans. Feral pigs carry seeds in their hooves. Hunters,

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A. Several stems can sprout from one rootstock. B. Prominent veins give the leaves a distinct pattern. C. Small flowers grow in the leaf axils or at the ends of branches. D. Fleshy berries are covered with bristles. (Forest and Kim Starr.)

hikers, and vehicles are responsible for long-distance dispersal. Seeds adhere to hikers’ boots, which may account for the spread of Koster’s curse from trail to trail or to other islands. Infestations in abandoned forest clearings formerly used to grow marijuana indicate another probable vector for long-distance dispersal. Seeds remain viable in the soil for four years, and plants can reach maturity and fruiting size in 6–10 months. Stems sprout from the root stalk and from cut stumps and also root where they contact moist soil. Even loose leaves have been known to grow roots. Impacts. In its native range, Koster’s curse lives only a few years before dying, due to disease or insect damage. However, in the absence of disease and insects where it has been introduced, the shrub can create monotypic thickets. Its high seed production, high seedling establishment, large seed bank, and early maturation give it the means to be a significant invader in a broad range of environments. Due to its rapid growth, Koster’s curse may dominate the understory in forests after only one year. By shading out understory native plant species, it inhibits forest regeneration and natural plant succession. It reduces biodiversity and is a serious threat to understory plants on tropical islands. It is considered one of the worst alien plants in Hawaiian natural ecosystems and is also a weed in plantation agriculture. Sheep will not eat it, and it is toxic to goats. Management. Because disturbance is the key to major invasions, control of feral pig populations will limit the amount of disturbed ground, as well as decrease the seed dispersal. Hikers and hunters should thoroughly wash their boots after leaving infected areas, so as to minimize seed dispersal. Because of the abundant seed production and seedbank, any control must be done on new stands before fruit sets for the first time. Most physical efforts at control, such as pulling up or cutting plants, fail unless they are followed by herbicide treatments. Plants are quickly replaced from the soil seed bank, and uprooted plants often resprout or reroot. Because of resprouting, mowing or cutting plants only once is not effective. Any physical control must be repeated for as long as 10 years to deplete root reserves and ensure eradication. Chemical applications of a broadleaf herbicide offer the best short-term control but are not practical in many areas of Hawai’i. Variation in results may be due to differences in

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Is Koster’s Curse Always a Curse?

I

n its native range in Puerto Rico, Koster’s curse is beneficial because it colonizes disturbed areas and is food for wildlife. It is used in Brazil as treatment for a skin infection, Leishmania braziliensis.

application techniques, and more research is needed, but more than one herbicide application is usually necessary. Herbicides should be used on seedlings and on uprooted plants to prevent sprouting. Glyphosate is effective as a foliar spray. A triclopyr solution is sometimes effective when applied to foliage, cut stump, or to basal bark. Biological control is the best possibility for a long-term solution. Although biological agents fail to eliminate the plant, they decrease its competitive advantage. Two insects that have been released in Hawai’i have met with only partial success. A thrips (Liothrips urichi) from Trinidad, released in 1953, is effective in open areas, such as pastures and fields, but not in shaded locations. A beetle (Lius peisodon), however, attacks plants in the shade. A fungus (Colletotrichum gloesporioides), introduced in 1986, provides some control in drier sites, both open and shaded, but is ineffective in wetter habitats. Three moths (Antiblemma acclinalis, Carposina bullata, and Mompha trithalama) released in the 1970s have been unsuccessful.

Selected References Francis, John K. “Clidemia hirta (L.) D. Don.” U.S. Department of Agriculture, Forest Service, International Institute of Tropical Forestry, San Juan, Puerto Rico, n.d. http://www.fs.fed.us/ global/iitf/pdf/shrubs/Clidemia%20hirta.pdf. Gerlach, Justin. “Clidemia hirta.” ISSG Global Invasive Species Database, 2006. http://www.issg.org/ database/species/ecology.asp?fr=1&si=53. Nelson, R. “Koster’s Curse” Untamed Science, 2010. http://www.untamedscience.com/biodiversity/ plants/flowering-plants/dicotyledons/myrtales/melastomataceae/clidemia/kosters-curse. Tunison, Tim. “Element Stewardship Abstract, Clidemia hirta.” Global Invasive Species Team. Nature Conservancy, 1991; modified 2009. http://wiki.bugwood.org/Clidemia_hirta.

n Lantana Also known as: red sage, yellow sage, prickly sage, big sage, blacksage, flowered sage, lantana wildtype, largeleaf lantana, prickly lantana Scientific name: Lantana camara Synonyms: Lantana aculeata, L. camara var. nivea, L. camara var. aculeata Family: Verbena (Verbenaceae) Native Range. Tropical North and South America, specifically the Caribbean Islands, including Bermuda, the Bahamas, Greater Antilles, Lesser Antilles, and Puerto Rico, and from Mexico south to Colombia and Venezuela. Because lantana has been cultivated for more than 300 years as an ornamental, it is difficult to determine exactly where it originated. Distribution in the United States. Southern United States, from North Carolina west to California. Also on all the main Hawaiian Islands, Puerto Rico, and the Virgin Islands. Description. Lantana has many cultivars, making it a highly variable species in its growth habit, flowers, leaves, growth rates, shade tolerance, spines, and toxicity to livestock.

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Lantana is a perennial shrub with multiple stems growing from its base, at or close to ground level. It may be as tall as 10 ft. (3 m). It is usually erect in open habitats, but prostrate, or occasionally clambering (climbing onto and over shrubs and trees) in scrubland or forests. It may grow in individual clumps or in thickets. Evergreen in the Tropics and Subtropics, lantana is deciduous in cooler climates. Stems are fourangled. Stems on plants that grow on the U.S. mainland usually have no spines, but the variety in Hawai’i usually has prickly stems. Yellow-green to green leaves are oval and broadly lance-shaped, 0.8–6 in. (2–15) cm long and 0.8–2.5 in. (2–6 cm) wide. They are opposite on the stem and stiff, with serrated edges. Covered with small rough hairs, the leaf surfaces feel rough, like fine sandpaper. When crushed, leaves are aromatic, reminiscent of black currents. The inflorescences, growing in the leaf axils near the ends Lantana has many cultivars and is widely available as an ornamental. of the stems, are compact, flat- (Native range adapted from USDA GRIN and selected references. topped flowerheads, about Introduced range adapted from USDA PLANTS Database, Invasive Plant 1 in. (2.5 cm) in diameter. Flo- Atlas of the United States, and selected references.) wer color is variable, typically becoming darker as the flowers age, changing from yellow to orange to red, or from white to pink to lavender. The central flowers and the outer ring of flowers are different colors. Lantana produces abundant fruit. Round, fleshy berries, 0.2 in. (6 mm) in diameter, hang in clusters like a blackberry. They are green when immature and purplish black when ripe. Each individual fruit contains 1–2 seeds. Related or Similar Species. Now endangered, pineland lantana, also called depressed shrubverbena, is native to Florida. It is distinguished from the invasive lantana by a distinctly tapered leaf base and yellow flowers. The two species, however, hybridize, making identification difficult. Introduction History. Lantana was introduced to Europe from Brazil in the seventeenth century. Although it may have been introduced to Europe multiple times, no records exist. In the 1700s, lantana was a favorite ornamental in Europe, leading to many cultivars. In

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A. Many stems grow from the base of the plant. (Rebekah D. Wallace, Bugwood.org.) B. Opposite leaves are toothed. (Forest and Kim Starr.) C. Round berries are fleshy. (Richard Old, XID Services, Inc., Bugwood.org.) D. and E. Flat-topped clusters of showy flowers almost cover the shrub. (Forest and Kim Starr.)

the 1800s and 1900s, lantana became widely distributed worldwide, with hundreds of cultivars and hybrids. No record indicates exactly when lantana was introduced to the mainland United States, but it was taken to Hawai’i as an ornamental in 1858. It became naturalized on the Hawaiian Islands by 1871 and was widespread. Plants are sold in nurseries throughout the United States. Habitat. Because so many cultivars and varieties exist, lantana has a broad tolerance to environmental factors and occupies a variety of habitats, including forests, riparian sites, pastures, and citrus groves. It thrives in both shady and sunny sites, but generally grows best in open, sunny locations, such as wasteland, forest edges, beaches, transportation corridors, and burned or logged forests. Somewhat shade tolerant, it is found beneath the canopy of open forests, but cannot grow in heavy shade. Lantana usually colonizes disturbed sites, and natural fires stimulate its growth. It benefits from destructive activities of foraging animals, such as pigs, cattle, sheep, or goats. It grows well on all types of well-drained soils, but cannot tolerate boggy conditions. Although resistant to both drought and salt spray, it does not grow on saline soils. Able to thrive in poor soils and quick to invade disturbed sites, plants may be used in reclamation of mine spoils. In Hawai’i, lantana occurs in low elevations that range from dry to moist, predominantly along roadsides, in vacant lots, pastures, forest, shrubland, and natural grassland. Worldwide, it is found in regions with 10–160 in. (250–4,000 mm) of annual rainfall. It grows from sea level to 6,500 ft. (2,000 m) elevation, but most varieties are limited by frost. Stems die back when temperatures drop to 28ºF (-2 C), but they resprout in spring. Reproduction and Dispersal. Reproduction is both sexual and vegetative. Under favorable temperature and moisture conditions, lantana has an almost continuous bloom period. In seasonal climates, peak flowering usually coincides with the rainy season. Flowers are pollinated by insects, especially butterflies and thrips. Reports of self-fertilization are conflicting. One plant produces about 12,000 fruit. Birds, and occasionally other animals, eat the fruit, which accounts for long-distance dispersal of the seeds. Six nonnative birds, including the Chinese Turtledove and the Common Myna (see Volume 1, Vertebrates, Birds, Common Myna), disperse lantana seeds in Hawai’i, where no native birds have been observed feeding on the fruit. Fruit that is not eaten becomes dry and remains on the shrub for some time. The low germination rate of seeds is enhanced by passage through a digestive

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tract. Germination requires high light conditions, and seedlings do not survive beneath the parent bushes. Given suitable conditions, germination can take place all year. Plants grow rapidly and may reach 10 ft. (3 m) tall in 3–4 years. Plants can regenerate from the base after stems are damaged. Large plants can survive fires and mowing because new stems grow from the base, but not from broken or damaged roots. Stems will root where they contact the soil, and new plants can be propagated by cuttings. Impacts. Lantana is a pest in both natural areas and in agriculture. By first growing on creek banks and roadsides, the shrub more easily invades adjacent disturbed natural ecosystems. It often forms dense thickets in disturbed forest and pasture, crowding out native species and reducing biodiversity. It dominates the understory layer of forests, where it suppresses growth of native plants. It is thought to have alleleopathic compounds, which limit growth of plants nearby. By interfering with forest reproduction, lantana can change forest communities into shrubland. In Hawai’i, lantana displaces native plants in dry habitats. Lantana can become the dominant understory shrub in orchards, plantations, or open forests. It is a weed in agricultural crops and reduces the carrying capacity of pasture. It is a serious economic pest in citrus groves in Florida, where its alleleopathic substances reduce vigor and productivity. Thick stands impede access to commercial forests and create fire hazards by increasing the biomass. Spiny varieties hinder human access and interfere with recreational activities, such as hiking. Leaves and unripe fruit are poisonous. If ingested by livestock, such as cattle, sheep, goats, or horses, or by wildlife, the plant can cause liver failure and death. Most animals avoid the plant. In home garden settings, children have been poisoned by eating the unripe fruit, occasionally causing death. Management. An integrated management approach, including physical removal, burning, chemicals, shading, prevention, and revegetation, is most effective. The best prevention, however, is to not purchase and plant lantana in the home garden and to maintain healthy ecosystems with native plant biodiversity. Rapid revegetation of disturbed areas, such as burns or cleared sites, will prevent lantana seedling development. Lantana cannot reestablish under the dense shade of closed tree canopies. Physical methods range from cutting off flowers to removal of entire plants. Spread can be prevented by removing flower heads or fruit clusters from the plant before they are ripe. Small plants can be hand-pulled. Fire or mowing reduces the biomass, thereby reducing the amount of chemicals required for herbicide applications. Fire is ineffective, however, unless followed by chemical treatments for several years. Digging out plants as follow-up is labor intensive and not practical for large stands. Chemical applications work best when clumps are first cut and herbicide is applied to the stumps or to the new sprouts. Regrowth should be sprayed when it is 1.5–5 ft. (0.5–1.5 m) tall. Foliar applications of glyphosate are not very effective, failing to prevent regrowth from the base. Fluroxypyr plus aminopyralid sprayed twice in six months works well, as does fluroxypyr or imazapyr applied to the base of the plant. Between 1902 and 1969, more than 20 insects were introduced to Hawai’i for biological control, with varying results. The most effective agents are a caterpillar (Hypena strigata), which defoliates plants; a fly (Ophiomyia lantanae), which destroys seeds; and the lace bug (Teleonemia scrupulosa), which damages the plant by feeding on leaves. Those introduced insects are now a problem on ornamental lantana shrubs, indicating that any biological control will be controversial because of the landscape plant industry and private gardens. A benefit of biological control is that it reduces the volume of individual plants, making other

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Uses of Lantana

P

lanted worldwide as an ornamental, lantana may also have value as an herbal medicine. It is used as a folk medicine for many ailments, including chicken pox, asthma, eczema, tumors, high blood pressure, tetanus, and rheumatism. Boiled leaves are applied to the skin to alleviate pain and reduce swelling. Lantana oil is used for itchy skin, as an antiseptic, and for such skin conditions as leprosy and scabies. Alkaloids may relieve constipation and lower blood pressure. Leaves contain an insecticidal or antimicrobial substance. Potatoes stored with lantana leaves, for example, sustain no damage from potato tuber moths (Phthorimaea operculella). Because of its toxicity, lantana offers possibilities for biocides or herbicides. Research has shown that a leachate can kill waterhyacinth.

control methods easier. No biological agent has totally controlled lantana, perhaps due to its genetic diversity. Different research is required for specific areas of the world, because what is effective in Australia may not control different varieties of lantana in Florida or in South Africa.

Selected References Francis, John K. “Lantana camara.” U.S. Department of Agriculture, Forest Service, International Institute of Tropical Forestry, San Juan, Puerto Rico, n.d. http://www.fs.fed.us/global/iitf/pdf/ shrubs/Lantana%20camara.pdf. MacDonald, Greg, Brent Sellers, Ken Langeland, Tina Duperron-Bond, and Eileen Ketterer-Guest. “Lantana species.” Excerpted from Identification and Biology of Non-Native Plants in Florida’s Natural Areas, by K. A. Langeland and K. Craddock Burks. IFAS Publication SP 257. Center for Aquatic and Invasive Plants, University of Florida, IFAS, 2008. http://plants.ifas.ufl.edu/node/223. Motooka, P., et al. “Lantana camara.” In Weeds of Hawai’i’s Pastures and Natural Areas: An Identification and Management Guide. College of Tropical Agriculture and Human Resources, University of Hawai’i, Manoa, 2003. http://www.ctahr.hawaii.edu/invweed/WeedsHI/W_Lantana_camara.pdf. Walton, Craig. “Lantana camara (Shrub).” ISSG Global Invasive Species Database. 2006. http:// www.issg.org/database/species/ecology.asp?fr=1&si=56.

n Multiflora Rose Also known as: Rambler rose Scientific name: Rosa multiflora Synonyms: Rosa cathayensis Family: Rose (Rosaceae) Native Range. Eastern Asia, including eastern China, Korea, Taiwan, and Japan. Distribution in the United States. Most of the contiguous United States except for the northern Rocky Mountain states and Great Plains states, from the Dakotas west to Idaho, and the desert states of Nevada and Arizona. Absent from Alaska, Hawai’i and Puerto Rico. Description. Multiflora rose is a thorny, perennial shrub that can reach 10–15 ft. (3–4.5 m) tall and be 9–13 ft. (2.7–4 m) wide. Many long, arching stems, called canes, which arise from the root crown, are covered with hard, recurved thorns. Leaves, on 0.5 in.

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(1.3 cm) long petioles, are alternate and pinnately compound, about 3–4 in. (8–10 cm) long. Each leaf has 4–11 oval or oblong leaflets, which are sharply toothed. The base of each leaf has a pair of fringed or finely dissected bracts called stipules. Showy panicles of fragrant flowers appear in May and June. Usually white, sometimes pink, flowers are 0.5–1 in. (1.3–2.5 cm) in diameter, with five petals. Clusters of fruit, called rose hips, hang from each panicle. The rose hips may be either glabrous or pubescent and become bright red as they mature in mid-to-late summer. Later in the fall, they become leathery. They do not burst to release seeds and remain on the plant. Each fruit contains an average of seven seeds, which are yellowish to tan and irregularly shaped, 0.08–0.16 in. (2–4 mm) long. Related or Similar Species. More than 80 species or subspecies of roses, some native, some escaped from cultivation, Because it was introduced multiple times and used for several purposes, and some confined to gardens, multiflora rose is widespread in the United States. (Native range adapted grow in the eastern United from USDA GRIN and selected references. Introduced range adapted States. Registered cultivars nu- from USDA PLANTS Database, Invasive Plant Atlas of the United States, and selected references.) mber an additional 8,000. Maccartney rose was brought from Asia to southeast Texas for use as a hedge row. Because it sprouts vegetatively and forms dense thickets, it has become invasive along the Gulf coast. Stems have both recurved and straight thorns. Each leaflet on the pinnately compound leaf is 1–3 in. (2.5–7.5 cm) long. White flowers with many yellow anthers grow in small clusters. Although named for the Cherokee Indians who cultivated it in the 1800s, Cherokee rose is native to China. Introduced by a plantation owner in 1759, this rose naturalizes so readily that it was believed to be native as late as 1916. It has many large, reddish-orange prickles, a threeleaflet compound leaf, and white flowers for a short time in early spring. It is a serious weed in the rich soils of the “black belt” in Alabama, where it occupies hundreds of acres of land. The dog rose, a scrambling species from Europe and western Asia, is not invasive and is prized for its large rose hips as a natural food source of vitamin C. The vines have recurved

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A. Canes are long and arching. (Ohio State Weed Lab Archive, The Ohio State University, Bugwood.org.) B. Leaflets have serrated margins. (James H. Miller, USDA Forest Service, Bugwood.org.) C. Leaf bases have fringed bracts. (James H. Miller, USDA Forest Service, Bugwood.org.) D. Showy flowers are usually white. (James H. Miller, USDA Forest Service, Bugwood.org.) E. The fruit, rose hips, remain on the plant. (James H. Miller, USDA Forest Service, Bugwood.org.) F. Plants have prominent recurved thorns. (Chris Evans, River to River CWMA, Bugwood.org.)

or hooked spines and pinnately compound leaves with 5–7 leaflets. Fragrant flowers can be deep pink or white but are usually pale pink. Sweetbriar rose from Europe, and rugosa rose from China, are both common and widespread in the eastern United States, but are generally not invasive. Young stems of sweetbriar rose are smooth, but become prickly and hairy with age. Flowers are pink to pale pink. Leaves of rugosa rose are a deep glossy green, heavily veined and wrinkled. Stems are very spiny, densely covered with needlelike thorns. Flowers range from white or yellow to pink or purple, and the rose hips are large, 1 in. (2. 5 cm) in diameter. Native rose species that may be confused with multiflora rose include pasture rose, climbing prairie rose, swamp rose, prickly rose, smooth rose, and Virginia rose, all with primarily pink flowers 2–3 in. (5–7.5 cm) in size. Two shrubby berry species are also similar. Allegheny blackberry has 1 in. (2.5 cm) white flowers, while purpleflowering raspberry has 2 in. (5 cm) pinkish-purple flowers. None of the native roses are invasive. Introduction History. Multiflora rose has been introduced into the United States many times since the late 1700s, both as garden plants and as root stock for ornamental roses. An introduction from Japan in 1886, of plants to be used as grafting stock for ornamental roses, is well documented. Multiflora rose is no longer used and is not available in nurseries. Beginning in the 1930s, the U.S. Soil Conservation Service recommended multiflora rose to check soil erosion and for use as living fences to control livestock. State conservationists recommended it as wildlife cover for ground birds and cottontail rabbits and as food for songbirds. Over 14 million free cuttings from state conservation departments were planted in West Virginia in the 1940s–1960s, and over 20 million were planted in North Carolina. However, some states such as Kentucky refused to promote multiflora rose, with the result that Kentucky as a whole is relatively free of invasion. Multiflora rose, however, is prominent in forested land in Kentucky. Plants were also planted on medians of highways, both as crash barriers and to reduce the glare of oncoming headlights. Rose hips are also used in tea for their vitamin C content.

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Habitat. A prolific grower, multiflora rose invades old fields and agricultural land in the southeastern United States. In the northeastern and midwestern states, it is predominantly a weed in pastures and other unplowed lands. On the Great Plains, it was frequently used as wind breaks. It can also be found in prairies, along roadsides, on hillsides, fence rows, right-of-ways, margins of swamps and marshes, and in open woods. Multiflora rose grows best on deep, well-drained soils, but tolerates a wide range of soil and environmental conditions. It grows in both shade and sun, but does best in full or partial sun. It grows in either damp or dry soils, but cannot tolerate standing water. It is less vigorous in the northern states because of cold winters, and is not found where winter temperatures drop below 28ºF (−33ºC). In contrast, south of central Georgia, it is only found as deliberate plantings because it needs cold temperatures to stimulate germination. Reproduction and Dispersal. Multiflora rose reproduces both sexually and vegetatively. A large plant may have 40–50 panicles, with an average of 50–60 rose hips each, meaning that an average mature plant can produce about 500,000 seeds per year. Approximately 90 percent of the seeds are viable. Long-distance dispersal is accomplished by winter-feeding birds, such as Cedar Waxwings, Mockingbirds, Starlings, Red-winged Blackbirds, and American Robins, which eat the fruit and expel the seeds. Passage through a bird’s digestive tract scarifies the seeds, which facilitates germination. Seedlings are often concentrated beneath places where birds perch. Deer also eat the fruit. Seeds remain viable for as long as 20 years and germinate easily. Seedlings grow close to the ground for the first 1–2 years. Local spread is due to the habit of the long, drooping canes, which root where the tips touch the soil. Impacts. Multiflora rose has both economic and ecological impacts. Over 45 million areas in the United States are infested with multiflora rose. Infestations lower land values of agricultural, forestry, and recreational areas. When used as a hedge between fields, it may lower crop yield by siphoning nutrients away from crops. Pastures on hilly terrain or steep slopes are often infested. Forage is reduced, and cattle avoid grazing pastures that support the thorny plants, resulting in a decrease in beef production. Because of its prolific growth and tendency to form dense, impenetrable thickets, it crowds out native plants, not only displacing the plant communities, but also the wildlife and insects that depend on them. Management. Type and effectiveness of physical control depends on the size of plants or the infested area. Although small seedlings can be pulled, removing plants by hand is timeconsuming. Repeated mowing will prevent establishment of seedlings, but it should be done 3–6 times per growing season for 2–4 years. Easily done in flat grassy pastures, mowing is difficult in wooded or brushy areas. Mowing cannot be done on mature clumps that are over 10 ft. (3 m) tall and 20 ft. (6 m) in diameter. Bulldozing of large plants and thickets is an option, but subsequent control of seedlings, which sprout on disturbed soil, is necessary. Burning has not been tried with multiflora rose, but it has been partly successful in Texas on Macartney rose, where 90 percent of top growth was killed. Regrowth from root crowns, however, occurred within two weeks. Periodic burning combined with spraying with herbicides is necessary to completely kill plants. Dead plant debris remaining from herbicide treatment can be efficiently burned. Any chemical control requires monitoring and follow-up because of the long-lived soil seed bank. Application of a foliar spray, such as glyphosate, 2,4-D, picloram, dicamba, triclopyr, or fosamine, in spring offers control if repeated for two years. Picloram, however, is not effective if applied directly to the soil. An advantage to fosamine is that it affects only woody species, leaving herbaceous species undamaged. Application of glyphosate or other herbicides to freshly cut stumps is very effective.

526 n SHRUBS Multiflora rose is tolerant to many North American insects and diseases. Any introduced biological control must not damage ornamental roses. Three possibilities are well established in the United States. Larvae of the European rose chalicid (Megastigmus aculeatus var. nigroflavus), a small torymid wasp, hatch within the seeds and feed on them. Although native to the same world region as multiflora rose, this insect was discovered in a New Jersey nursery in 1917, where rose seed was imported from Japan for creation of root stocks. The insect spread slowly from that location. After overwintering in the empty seed, the insects emerge as adults the next summer to lay eggs and renew the cycle. Adult chalicids are limited flyers and remain with the plant unless the seeds are transported. Because of the limited flying ability of the adults, the species is not widespread in the United States, and would have to be introduced locally where multiflora rose is invasive. Because most plants were distributed by cuttings, not seed, distribution of chalicid wasp lagged behind that of multiflora rose. Because the rose chalicid has been found to infect 95 percent of seeds imported from Japan, it is expected that it will infect the same percentage in the United States. Although it may take 3–5 decades, it has the potential to drastically reduce the invasiveness of multiflora rose. The virus-like rose rosette disease, which is native to North America and spread by a tiny native eriophyid mite (Phyllocoptes fructiphilus), causes flowers to develop abnormally and leaves and shoots to turn deep red or purplish. Stems are enlarged and become thornier. Plants also develop a broom-like growth from profuse sprouting of lateral buds. When temperatures drop below 14ºF (-10ºC), the affected canes die. The disease was first reported in California and Wyoming in 1941, on both ornamental roses and on the wild native Woods’ rose, which is common to the Rocky Mountains, western Plains, California and Arizona. The disease spread eastward, and was found on a multiflora rose in a Nebraska nursery in 1964 and in Pennsylvania and West Virginia by 1994, sparking concern over its potential damage to ornamental roses. This pathogen has been fatal to multiflora rose from the Great Plains to Pennsylvania and Maryland. It also affects ornamental roses, causing a yellow pattern on the leaves, increased thorniness, clumped and wrinkled foliage, and broom-like lateral bud growth. The pathogen is disseminated by air currents and can also be transmitted through grafting affected plants. The rose stemgirdler (Agrilus aurichalceus) is a small brownish-golden metallic colored beetle, 0.2–0.4 in. (5–9 mm) long. Originally from Europe, it is now established in eastern North America. As the larvae burrow beneath the bark, they girdle the stem, which kills the stem above the girdle. A drawback is that the stemgirdler may also affect other rose species and some blackberries and raspberries (Rubus spp.).

Selected References Amrine, J. W., Jr. “Multiflora rose.” In Biological Control of Invasive Plants in the Eastern United States, by R. Van Driesche et al. USDA Forest Service Publication FHTET-2002-04, 2002. http:// www.invasive.org/eastern/biocontrol/22MultifloraRose.html. Bergmann, Carole, and Jil M. Swearingen. “Multiflora Rose (Rosa multiflora).” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservational Alliance’s Alien Plant Working Group, 2009. http://www.nps.gov/plants/alien/fact/pdf/romu1.pdf. Eckardt, Nancy, and TunyaLee Martin. “Element Stewardship Abstract, Rosa multiflora.” Global Invasive Species Team, Nature Conservancy, 1987; revised 2001; modified 2009. http:// wiki.bugwood.org/Rosa_multiflora.

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n Rattlebox Also known as: Chinese wisteria, Spanish gold, scarlet wisteria, red sesbania, purple sesbane, false poinciana, black acacia Scientific name: Sesbania punicea Synonyms: Sesbania tripetii, Daubentonia punicea Family: Legume (Fabaceae) Native Range. South America, specifically Uruguay, southern Brazil, southern Paraguay, and northeastern Argentina. Distribution in the United States. Southern United States, from Texas and Arkansas east to Florida and as far north as Virginia. It has recently been recorded west of the Rocky Mountains in the Central Valley of California. Description. Rattlebox is a deciduous woody shrub or small tree, growing as tall as 15 ft. (4.5 m). The gray or reddishbrown bark is covered with lenticels. Mature trees have an open, spreading crown. The alternate leaves are pinnately compound, 4–8 in. (10–20 cm) long, with 10–40 dark green leaflets. Oblong leaflets, each about 1 in. (2.5 cm) long, have pointed tips and are arranged opposite on the leaf stem, with no terminal leaflet. Leaflets are droopy. Orange-red or coral-colored flowers, with the characteristic shape of legumes or peas, appear in spring and early summer. Flowers, each 0.8–1.2 in. (2–3 cm) long, hang clustered in dense sprays up to 10 in. (25 cm) long. The dark-brown woody seed pods, which hang in clusters on short stalks, are 3–4 in. (7.5–10 cm) long with a pronounced pointed tip. Pods are distinguished by four wingRattlebox grows best in climates with long, hot summers, in California like projections running the and the southern states. (Native range adapted from USDA GRIN and length of the seed pod. The 3– selected references. Introduced range adapted from USDA PLANTS 10 seeds are loose inside parti- Database, Invasive Plant Atlas of the United States, and selected tions within the pod, making a references.)

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A. Rattlebox has a spreading crown. (Charles T. Bryson, USDA Agricultural Research Service, Bugwood.org.) B. Compound leaves have no terminal leaflet. (Karan A. Rawlins, University of Georgia, Bugwood.org.) C. Seed pods are distinctively shaped. (Karan A. Rawlins, University of Georgia, Bugwood.org.) D. Showy flowers grow in long clusters. (Karan A. Rawlins, University of Georgia, Bugwood.org.) E. Loose seeds inside the pods make a rattlling sound. (Karan A. Rawlins, University of Georgia, Bugwood.org.)

rattling sound similar to a rattlesnake when shaken. Seeds are released when the pod shatters, but seed pods often remain on the plant through the winter. Related or Similar Species. The genus Sesbania has many species, both annual and woody. Some are native to the United States, and some have commercial value. The three described below are all deciduous and have the distinctive rattling seedpods. Bagpod, also called bladderpod, is an annual, native to the southeastern United States, that reaches 13 ft. (4 m) tall. Found on disturbed moist or wet sites, it has a smooth stem and few or no branches. Stem tips have dense white hairs. Leaves are alternate and pinnately compound, but longer than rattlebox leaves, as long as 12 in. (30 cm). Leaves have 20–40 leaflets, each 1.2 in. (3 cm) long, with smooth margins. Leaflets are very hairy when they first emerge, but become smooth as they mature. Flowers usually have yellow petals, but they are variable and often pink or red. The fruit is a dry, smooth inflated pod 0.8–2.4 in. (2–6 cm) long, containing two seeds. Green plants are not favored by livestock, but dried, mature seed pods may be eaten by goats and cattle in fall and winter. This plant, however, is toxic, especially the seeds. Freshly dried seeds are more toxic than older ones remaining on the plants. Bagpod often grows intermixed with hemp sesbania. Hemp sesbania, native to the United States, is an annual growing to 13 ft. (4 m) tall, with few to no branches. Its bark is smooth, and stem tips are not hairy. Leaves can be as long as 12 in. (30 cm), with 20–70 leaflets. Linear or oblong leaflets, 1.5 in. (3.5 cm) long, have smooth margins and pointed tips. Leaflets are smooth above, but waxy beneath. The yellow flowers may be streaked or spotted with purple. Seedpods are smooth, 4–8 in. (10–20 cm) long, and contain 30–40 seeds each. It grows in disturbed sites and along water courses as far north as New York. Hemp sesbania is a noxious weed in Arkansas because it invades crops, such as peanuts and cotton. Drummond rattlebox, also native to the United States, is a woody perennial shrub or small tree growing 2–15 ft. (0.6–4.5 m) tall. The green or light-brown bark is smooth. Leaves are alternate, 4–8 in. (10–20 cm) long, with 20–50 leaflets, each 0.5–1.5 in. (1.2– 4 cm) long. The dull-green leaflets fold up in response to hot sun. Although it has many branches in its canopy, their wide separation gives the tree an open appearance. The 0.5 in. (1.2 cm) flowers are yellow, sometimes streaked with red, hanging in 2 in. (5 cm) long clusters. The shrubby tree occupies low-lying wet sites. In the northern part of its range,

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the higher aerial parts freeze back in cold weather, but the lower woody parts remain unharmed. Introduction History. Rattlebox was introduced to California in 1930, and probably much earlier to the East Coast. Because of its showy coral-colored flowers and persistent, rattling seed pods, this species is still sold and planted as an ornamental. It has escaped cultivation and invaded natural habitats. Habitat. Rattlebox prefers moist areas with long, hot summers and is found along rivers and streams, where it receives full sun. It is also somewhat shade tolerant, and young plants can be found growing in the shade of mature rattlebox trees. It can survive freezing conditions for a few days. Leaves are damaged at 23ºF (−5ºC), and the entire plant will die at 14ºF (−10ºC). Reproduction and Dispersal. Rattlebox reproduces solely by seeds. Each plant produces hundreds of seed pods and thousands of seeds each year. Pods continue to fall from the branches almost all year. Buoyant seed pods, which can float for up to 10 days, are dispersed by water and have a high germination rate, especially after the seed coat has been abraded by sandy running water. Seeds that fail to germinate remain dormant in the soil for years. Seed counts have averaged over 100 per sq. ft. (1,000 per m2). Seedlings grow quickly, as much as 3.3 ft. (1 m) in the first year. Plants become reproductively mature in their second year. Impacts. Rattlebox displaces native vegetation, which in turn decreases habitat for wildlife and reduces biodiversity. Its worst impact is around water bodies, such as rivers, lakes, and stream banks. Dense thickets that cover 50–100 percent of the ground can interrupt water flow and alter water quality. Thickets also block access for recreational uses. By colonizing gravel bars and islands, the plants increase channel roughness, which increases flood potential. All parts of rattlebox, especially the seeds, are poisonous to birds, reptiles, humans, and other mammals. Even a few seeds can be fatal to birds. The toxic component is saponic glycosides. Symptoms of ingestion include nausea and vomiting, associated with abdominal pain and diarrhea. Severe reactions result in respiratory failure or death. Rattlebox is included on the list of toxic plants for horses. Management. The best control is to limit planting of rattlebox. However, if stands are small, young plants can be removed by physical means before seeds are produced. Because the root system is not large, pulling plants from wet soil is not difficult. Mulches provide some control but are not feasible in large areas. Attempts to drown the plant by flooding are not effective, and the plant is difficult to control in wetlands. During flooding, the lower part of the stem splits and grows new roots, which help prop up the plant in unstable, mucky soils. Mowing is effective but usually cannot be accomplished in wet soils where rattlebox grows. Large plants can be cut, and the stumps treated with herbicides. Physical removal must be repeated for several years because seeds remaining in the soil seed bank will continue to sprout. Whatever method of removal is used, it is important to avoid disturbing the site. Little research has been conducted on chemical control of rattlebox. Use of glyphosate and triclopyr was not successful in site trials in Florida. Trees sprayed with glyphosate in California turned yellow, but results were not conclusive. No biological controls are currently used in the United States. Three insects from Argentina are being investigated in South Africa. The sesbania flower beetle (Trichapion latrivetre) and the sesbania seed weevil (Rhyssomatus marginatus) attack seed pods and seeds, reducing production as much as 98 and 84 percent, respectively. The sesbania stem borer (Neodiplogrammus quadrivittatus), also a weevil, damages and kills trees.

530 n SHRUBS

Selected References Hall, David W., Vernon V. Vandiver, and Jason A. Ferrell. “Hemp Sesbania, Sesbania exaltata (Raf.) Cory.” Institute of Food and Agricultural Sciences (IFAS), University of Florida. 2009. http:// edis.ifas.ufl.edu/fw039. Hall, David W., Vernon V. Vandiver, and Brent A. Sellers. “Bagpod (Bladderpod), Sesbania vesicaria (Jacq.) Ell.” Institute of Food and Agricultural Sciences (IFAS), University of Florida.2009. http:// edis.ifas.ufl.edu/fw038. Hunter, John C., A. Gerrit, and J. Platenkamp. “The Hunt for Red Sesbania.” Cal EPPC News (Quarterly newsletter of the California Exotic Pest Plant Council) 11(2): 4–6, 2003. http://www.cal-ipc.org/ resources/news/pdf/cal-ipc_news5109.pdf. Russell, Alice B, James W. Hardin, Larry Grand, and Angela Fraser. Poisonous Plants of North Carolina. North Carolina State University, 1997. http://www.ces.ncsu.edu/depts/hort/consumer/poison/ Sesbapu.htm “Sesbania drummondii (Poisonbean).” Native Plant Database, Lady Bird Johnson Wildflower Center, 2010. http://www.wildflower.org/plants/result.php?id_plant=SEDR. “Spanish gold, rattlebox, Sesbania punicea.” Center for Aquatic and Invasive Plants, University of Florida, IFAS, 2009. http://plants.ifas.ufl.edu/node/418.

n Tropical Soda Apple Also known as: Sodom apple Scientific name: Solanum viarum Synonyms: S. chloranthum, S. viridiflorum, S. khasianum var. chatterjeeanum Family: Potato (Solanaceae) Native Range. South America, from Brazil south through Paraguay to northeastern Argentina and Uruguay. Distribution in the United States. Southeastern states, from Texas east to Florida, and north to Tennessee and North Carolina. Also in New York State, Pennsylvania, and California. Description. Tropical soda apple is a perennial shrub that grows 3–6 ft. (1–2 m) tall, and is usually as broad as it is tall. While the sturdy stems persist in mild winter climates, they may die back during unfavorable seasons. Deeply lobed leaves, somewhat resembling oak leaves, grow on distinct petioles. Leaves are alternate, 4–8 in. (10–20 cm) long, and 2–6 in. (5–16 cm) wide. Lobes are broad and pointed. Leaves and stems are covered with soft, fine hairs and appear velvety except for the prickles. Most parts of the plant, including leaves, stems, pedicels, petioles, and calyxes, have thick, white to yellowish, straight prickles or thorns up to 0.4 in. (1 cm) long. Rigid prickles line the midvein and secondary veins on both surfaces of leaves and are even more concentrated on the petioles. The root system is extensive. Feeder roots, just a few inches below the soil surface, are 0.25–1 in. (0.6–2.5 cm) in diameter and can extend 3–6 ft. (1–2 m) away from the root crown. Roots have adventitious buds which sprout into new plants. Although plants may flower any time of year, most flowering occurs from September through May. The small flowers with five white petals, curved backwards as is typical in the potato family, grow in small terminal clusters on the stems below the leaves. Fruit, each about the size of a golf ball, 1–1.5 in. (2.5–4 cm) in diameter, is light green with dark-green streaks when immature, resembling a tiny watermelon. As they mature, the smooth skin turns a dull yellow, and the fruit looks like small apples and smell like apples or plums. Although smooth, the skin is leathery, surrounding a thin layer of pale green mucilaginous pulp. The reddish-brown bitter seeds, 0.1 in. (2.5 mm), are also mucilaginous and slightly flattened.

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Related or Similar Species. Several prickly Solanum species are found in the southeastern United States. Two nonnative species and one species native to the western United States are considered invasive. Although turkey berry, also known as bushy white solanum, gully-bean, Thai eggplant, devil’s fig, or susumber, was introduced to Florida more than 100 years ago, it has been recognized as invasive only recently. It is a pantropical weed with an unknown origin, probably West Africa, Central or South America, or Asia. Turkey berry is found in Alabama, Florida, Maryland, Hawai’i, Puerto Rico, and the Virgin Islands. A prickly treelike shrub as tall as 10 ft. (3 m), it grows in a variety of habitats, from wetlands to rocky hillsides. Its leaf shape is highly variable and may be evenly lobed, oddly lobed, or unlobed. Stems and leaves, which may have either straight or curved prickles, are covered with stellate (star-shaped) hairs. Tropical soda apple has rapidly increased its range since it was identified Flower stalks are covered with in Florida in 1988. (Native range adapted from USDA GRIN and selected glandular hairs. Petals in the references. Introduced range adapted from USDA PLANTS Database, terminal flowers are bright Invasive Plant Atlas of the United States, and selected references.) white and are not recurved. Turkey berry is grown for its edible yellow fruit the size of grapes. Flower and fruit appear year-round in tropical and subtropical climates, and seeds are dispersed by birds. Plants grow into thickets because of sprouts from lateral rhizomes. Turkey berry invades disturbed areas, such as pastures, roadsides, forest clearings, and damp waste areas. It is also cultivated in home gardens for its fruit, even though recent studies indicate that it may be carcinogenic to humans and poisonous to animals. Wetlands nightshade, also called wetlands soda apple, aquatic soda apple, Tampico soda apple, or scrambling nightshade, is native to Mexico, Belize, and the West Indies. First recorded on the Dry Tortugas in 1974, it had spread to mainland Florida by 1983. Wetlands nightshade is limited to Florida. It grows along rivers and in cypress stands in either full shade or full sun. The plant has a clambering vine-like habit, growing as tall as 15 ft. (4.5 m) and forming large, tangled stands. The long, narrow leaves are distinctive,

532 n SHRUBS

A. Infestations of shrubs displace forage plants in pastures. (Charles T. Bryson, USDA Agricultural Research Service, Bugwood.org.) B. Stems and leaf veins have sharp thorns. (Florida Division of Plant Industry Archive, Florida Department of Agriculture and Consumer Services, Bugwood.org.) C. Five white petals on the flowers curve backward. (Rebekah D. Wallace, Bugwood.org.) D. The small striped fruit ripens to yellow. (Florida Division of Plant Industry Archive, Florida Department of Agriculture and Consumer Services, Bugwood.org.)

up to 6.3 in. (16 cm) long and 0.6–2.2 in. (1.5–5.5 cm) wide, with wavy, lobed, margins. All prickles, whether on stems or on leaves, are curved, not straight. Veins on the upper surface of leaves have straight hairs, and leaf surfaces and stems are covered with stellate hairs. It is tolerant of frost and temporary high water. The plant flowers from May to January. Small, pea-size, red berries, which have no dark markings when green, hang in clusters opposite the leaves. Dispersal is by seeds and by stem fragments transported in water. New stems emerge annually from the plant’s base, and plants also root at leaf axils. Wetlands nightshade prefers areas that are regularly flooded. It has infested approximately 500–750 ac. (200–300 ha) of marshlands, cypress swamps, and other riparian habitat in southwestern Florida. Wetland nightshade displaces desirable plants, such as pickerelweed and forms dense thickets that block access and waterways for both wildlife and humans. Silverleaf nightshade, which is also known as tomato weed or white horsenettle, is a perennial shrub native to northeastern Mexico and southwestern United States. Listed as invasive in Florida and many other states, it was probably transported in ballast or as bedding in livestock railroad cars. Although it may grow to 3 ft. (1 m) tall, the stems die back to the root system in winter. The dark-green to pale, grayish-green leaves are variable, usually lance shaped, 1–4 in. (2.5–10 cm) long and 0.4–1 in. (1–2.5 cm) wide. Margins may be slightly lobed or wavy. All leaves and stems are pubescent, making the plant appear silvery green. Leaves are covered with stellate hairs, and both stems and leaves have yellow or brown colored prickles. The inflorescence, a cyme, has 1–7 flowers with bright blue to purple, or sometimes white, corollas. Fruit is a dehiscent berry 0.4–0.6 in. (1–1.5 cm) in diameter, and one plant may have 40–60 fruits, each with 60–120 tiny seeds. Silverleaf nightshade is a weed in cultivated land, orchards and pastures, primarily in regions with low rainfall. Several other introduced nightshades can be invasive locally. Heartleaf horsenettle is a forb, while purple African nightshade and shrubby nightshade are shrubs. Climbing nightshade and orangeberry nightshade can be both shrubby and vine-like. Several native species may be confused with tropical soda apple. Cockroach berry, also called Devil’s apple or love-apple, is a shrub found in the southeastern United States, Texas, and the West Indies. It is distinguishable from tropical soda apple by its smaller red

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fruit and stems that are more densely covered with prickles. Carolina horsenettle, a forb native to the southeastern states, has become a weed of disturbed areas further north and further west. Both plants and prickles are usually shorter, and flowers are lavender to white. Western horsenettle, also known as Torrey’s nightshade, is native to Kansas, Arkansas, and Texas, but now occurs in Florida and southern Georgia. Flowers are purple with a green center, and it has pale-yellow fruit. Plants are covered with stellate hairs. Buffalobur is native to the Great Plains but is an occasional weed in the southeastern states. Leaves are pinnatifid (deeply lobed) and covered with stellate hairs and straight prickles. The very prickly calyx completely covers the fruit. Introduction History. The method of arrival of tropical soda apple into the United States is not known, but seeds were a likely contaminant in seed shipments or in hay. Seeds may have been in bags of manure used in composting, or attached to someone’s shoes. Plants were probably present in Florida as early as 1981, before it was identified and collected in 1988. (Reports in the early 1960s are now known to have been misidentifications of cockroach berry.) By 1990, plants had infested 24,700 ac. (10,000 ha) in Florida; by 1993, 400,300 ac. (162,000 ha); and by 1995, 1,235,500 ac. (500,000 ha). Habitat. Tropical soda apple invades agriculture land, riparian areas, recreation areas, and disturbed sites that are seasonally wet. Soil disturbance, such as disking, trampling by cattle, rooting by hogs, or even cleaning of ditches enhances establishment of plants. It is commonly found in damp waste areas, such as pastures, roadsides, and ditch banks, and in sugarcane fields, rangeland, and citrus groves. It grows in both open and semi-shaded sites, and prefers sandy soils on poorly drained level land. Although plants can survive very wet soils, more than three weeks of standing water will kill them. Seeds will sprout, however, when the water recedes. Reproduction and Dispersal. Although tropical soda apple’s main reproduction method is through abundant seed production, it also reproduces vegetatively. Plants flower and produce fruit all year and may have both mature and immature fruit at the same time. Plants average 125 fruit, each containing 180–420 seeds, meaning that each plant can produce approximately 50,000 seeds, of which 70 percent are viable. In delta soils in Mississippi, 8–10 plants can produce approximately one million seeds each year. Seeds are dispersed locally by livestock, especially cattle, and by wildlife, which are attracted to the sweetsmelling fruit. Raccoons, deer, feral hogs, and birds eat the fruit and expel the seeds. Seeds cannot germinate within the fruit, and scarification in a digestive tract promotes germination. One cow patty can hold 150 seeds, and plants are often concentrated where cattle rest. Spread to other counties and states is frequently due to the movement of livestock that have recently ingested tropical soda apple. Seeds are also inadvertently dispersed as contaminants in hay, grass seed, grass sod, or on machinery. Approximately 20 percent of the seed crop remains dormant for up to several months. Germination usually occurs during a dry season, October to May in Florida, but depends on temperature, light, and age of the seed. Older seeds lose viability, and seeds deeper than 6 in. (15 cm) in soil probably will not germinate. White seeds are not viable. Plants can grow from seed to maturity in 105 days. Root segments, branches, and old root crowns may sprout new plants. Impacts. Tropical soda apple is both a pest in agricultural land and a threat to native ecosystems. It is a competitive weed in agricultural crops, such as vegetables. The plant is an alternate host for a number of viruses and pathogens that cause disease in crops, such as tomatoes, cucumbers, potatoes, and tobacco. It also carries a fungal pathogen (Alternaria solani) that also causes disease in food crops. Several crop pests, including tobacco and tomato hornworms, Colorado potato beetle, tobacco budworm, tomato pinworm, green peach

534 n SHRUBS aphid, silverleaf whitefly, and soybean loper, use tropical soda apple as an alternate host. Prickles harm both foraging animals and humans who harvest crops. Plants infest thousands of acres of pasture and lawn in the southeastern United States. The rapid growth of tropical soda apple lowers carrying the capacity of pastures by displacing forage plants. From 1992 to 1993, infestations in pastureland in Florida doubled, to 388,300 ac. (157,145 ha). Although cattle eat the fruit, they avoid the prickly leaves and stems. Cattle undergo heat stress when they are forced to remain in sunny sites because impenetrable, prickly thickets impede their movement to shade. Costs due to control of tropical soda apple or to crop damage are difficult to assess, but the plant has the potential to be a major problem in the southern states. In 1994, losses to the cattle industry in Florida were estimated at more than $11 million. Costs could extend into the billions of dollars annually. Infestations of tropical soda apple disrupt ecosystems, displacing native plants and reducing biodiversity in natural areas. The plant infests oak and palm hammocks and cypress (Taxodium spp.) island stands in Florida. By creating a physical barrier, the prickly plants restrict movement of wildlife. Its rapid growth interferes with restoration of phosphate mine reclamation. Plants can create a monoculture covering 50 or more acres. Although eaten by animals, fruit of tropical soda apple contains a glyco-alkaloid called solasodine, a substance poisonous to humans. A lethal dose is 200 fruit. Management. Because tropical soda apple spreads quickly to form large patches, early detection and removal is important. It is also important to prevent fruit and seed development and dispersal of seeds. Cattle that may have eaten tropical soda apple fruit should be held for several days before being shipped elsewhere. All equipment, including vehicles, mowers, tractors, clothing, and shoes, must be thoroughly cleaned to prevent transport of seeds. Physical control may be accomplished by hand-pulling small populations. Entire plants, including fruit, stems, and roots, should be removed and destroyed. Large stands may be mowed to prevent formation of flowers and fruit. Chemical applications are effective on new sprouts after plants have been mowed. Although glyphosate, imazapyr, picloram, dicamba, and triclopyr are all effective, triclopyr works best. Because many economically important crops, including peppers, tomatoes, tobacco, eggplant, and potato, are closely related to tropical soda apple, any use of biological control must be host-specific to the invasive species of Solanum. Of the numerous agents investigated, two pathogens and four insects offer potential. Ralstonia solanacearum, a soil-born bacterium, causes tropical soda apple plants to wilt and die, but it can also attack crops if they come into contact with contaminated soil, equipment, or irrigation water. A strain of the tobacco mild green mosaic tobamovirus (TMGMV U2) is lethal to tropical soda apple. A defoliating leaf beetle (Leptinotarsa texana) and a leaf-feeding tortoise beetle (Metriona elatior) do not appear to harm Solanum-related crops, but more testing is required. A weevil (Anthonomus tenebrosus) destroys the contents of flower buds, which inhibits fruit production. A leaf-feeding beetle from South America (Gratiana boliviana), which is host-specific to tropical soda apple, was released in 2003. Although a high population of insects is necessary for total control, the beetles affect the plant’s competitive ability by reducing its vigor and the number of fruit. Small infestations require a release of 100–300 beetles, while dense stands need 300–500 individuals, all of which will reproduce. Because the beetles do not feed in winter, tropical soda apple plants will rebound where winters are mild.

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Benefits of Tropical Soda Apple

T

ropical soda apple has been cultivated in Mexico and India as a source of steroids, made from the solasodine that causes the fruit to be poisonous to humans. These steroids are useful in cancer treatment, Addison’s disease, rheumatic arthritis, and in the production of contraceptives.

Selected References Coile, Nancy C. “Tropical Soda Apple, Solanum viarum Dunal: The Plant from Hell.” Botany Circular No. 27, Florida Department of Agriculture and Consumer Services, Division of Plant Industry, 1993; revised 1996. http://www.doacs.state.fl.us/pi/enpp/botany/botcirc/TSA-circ27-1996.pdf. Cuda, J. P., D. Gandolfo, J. C. Medal, R. Charudattan, and J. J. Mullahey. “Tropical Soda Apple, Wetland Nightshade, and Turkey Berry.” In Biological Control of Invasive Plants in the Eastern United States, by R. Van Driesche et al. USDA Forest Service Publication FHTET-2002-04, 2002. http://www.invasive.org/eastern/biocontrol/23SodaApple.html. National Biological Information Infrastrucure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Solanum viarum (Shrub).” ISSG Global Invasive Species Database, 2005. http:// www.issg.org/database/species/ecology.asp?si=265&fr=1&sts=&lang=EN. Sellers, Brent, Jay Ferrell, J. Jeffrey Mullahey, and Pat Hogue. “Tropical Soda Apple: Biology, Ecology and Management of a Noxious Weed in Florida.” SS-AGR-77. Agronomy Department, Florida Cooperative Extensive Service, Institute of Food and Agricultural Sciences, University of Florida, 1993; revised 2009. http://edis.ifas.ufl.edu/pdffiles/UW/UW09700.pdf.

n Yellow Himalayan Raspberry Also known as: robust blackberry, wild blackberry, wild raspberry, yellow raspberry, cheeseberry Scientific name: Rubus ellipticus Synonyms: Rubus flavus, R. gowreephul Family: Rose (Rosaceae) Native Range. Foothills of the Himalaya Mountains, from Kashmir east through Nepal and southern China, and in tropical and subtropical India and Southeast Asia. Distribution in the United States. Hawai’i. Description. Yellow Himalayan raspberry is a robust evergreen shrub with very long stems or canes that may reach 15 ft. (4.5 m). Berry plants like this are often called brambles because of the arching and intertwining prickly stems. The hardy, perennial roots grow new stems each year, increasing the density and size of the stand. Stems, leaves, and inflorescences are densely covered with conspicuous prickles and reddish hairs. Some hairs are stout and curved, while others are fine and straight. Leaves are alternate and palmately compound, on prickly petioles about 1 in. (2.5 cm) long. The three leaflets are thick and hairy, with sawlike toothed margins. Leaflets are broadly oval, 2–4 in. (5–10 cm), with the terminal leaflet being slightly larger. It is the only raspberry species in Hawai’i with light-green oval leaves that are blunt and do not terminate in a point. The underside of leaves is lighter in color than the top, with downy hairs.

536 n SHRUBS About 20 small white flowers with five petals each are clustered on compact panicles, 2–5 in. (5–10 cm) long, at the ends of the stems. The prickly flowers are pollinated by insects. Fruits are oval or round yellow berries, about 0.5–1 in. (1.5–2.5 cm) long. It is the only yellow fruited raspberry in Hawai’i. Related or Similar Species. Hawai’i has both native and introduced species of raspberry and blackberry. Yellow Himalayan raspberry is considered the worst, but other nonnatives are also considered extremely invasive. The native Hawaiian blackberry, or akala, is the only deciduous raspberry species in Hawai’i. Growing in mesic to wet forests and subalpine woodlands at 2,200–10,000 ft. (660–3,070 m), it has dark pink flowers and less prickly, pale-colored stalks. Another native blackberry, akalakala, is rare, with a more localized distribution. Several nonnative Rubus speYellow Himalayan raspberry is one of several Rubus species that are cies have been naturalized in invasive in Hawai’i. (Native range adapted from USDA GRIN and selected Hawai’i. Himalayan blackberry references. Introduced range adapted from USDA PLANTS Database, is a sprawling evergreen shrub Invasive Plant Atlas of the United States, and selected references.) with canes as long as 10 ft. (3 m). In spite of its name, it is native to Western Europe. Canes, which can be erect, decumbent, or trailing, are angled and furrowed, with straight or curved prickles, 0.25–0.4 in. (0.5–1 cm) long. Young canes are pubescent, but become almost glabrous as they age. The five leaflets in the compound leaves, glabrous on the upper surface but fuzzy below, are large and broad, with coarsely toothed margins. Leaves on flowering canes are smaller, with 3–5 leaflets, and all petioles have hooked prickles. The inflorescence is a large terminal cluster emerging from lower leaf axils. Peduncles and pedicels are prickly. The white or rose-colored flowers, 0.8–1 in. (2–2.5 cm) in diameter, have broad petals. Fruit is a typical berry, a cluster of round, black, succulent drupelets, 0.8 in. (2 cm) long. Because Himalayan blackberry canes will root where the tips contact soil and suckers may emerge from roots or cuttings, the plant creates impenetrable thickets on disturbed land and in riparian areas. It is commonly found in pastures, right-of-ways, creek gullies, and stream edges, where it tolerates periodic flooding of

YELLOW HIMALAYAN RASPBERRY n 537

A. Arching canes can be 15 ft. (4.5 m) long. B. Stems are covered with prickles and stiff hairs. C. The terminal leaflet is larger than the other two leaflets. D. Small flowers are white. (Forest and Kim Starr.)

both fresh and brackish water. It grows on many types of soil, but requires moisture. Plants are reported to grow at elevations over 6,000 ft. (1,830 m). Himalayan blackberry was introduced to North America in 1885, probably for its berries, and is now widespread in the western states, several midwestern and eastern states, and in Hawai’i. It spreads locally by vegetative means and long-distance by seed when berries are eaten by birds or mammals. Thickets may produce 700–130 seeds per sq. ft. (7,000– 13,000 per m2). By dominating range and pasture, Himalayan blackberry brambles shade out and displace native species. Livestock avoid the prickly plant, and thickets may prevent even large animals from reaching water. It hinders access for maintenance and recreational activities, and its thick jumble of branches creates a fire hazard. Less prickly than yellow Himalayan raspberry, sawtooth blackberry, which is native to the eastern United States, is the most widespread nonnative raspberry in Mau’i. It is distinguishable by its white flowers, black fruits, and pointed leaf tip. It is considered a serious pest in wet forests and pastures on several islands. Native to tropical Asia, West Indian raspberry is a small prickly shrub 6 ft. (1.8 m) tall, with white flowers and red fruit. It has 5–7 long, pointed leaflets. This plant is found on most islands of Hawai’i, where it displaces native plants in pastures and impedes passage because of its dense growth. Snowpeaks raspberry, native to India and Southeast Asia, has 5–9 leaflets, which are also pointed. Lavender flowers and dark-red to black fruit with white hairs distinguish it from yellow Himalayan raspberry. It occurs on several islands with similar impacts. Introduction History. Deliberately introduced to the town of Volcano on the island of Hawai’i for its tasty yellow fruits in the early 1960s, yellow Himalayan raspberry has since escaped from cultivation. People also like the plant as an ornamental, and in some cases to

Brambles of Himalayan Blackberry

B

rambles of Himalayan blackberry may be so dense and intertwined that young sheep and goats that become entrapped may die from hunger or thirst if not rescued.

538 n SHRUBS check soil erosion. Because it is a noxious weed in Hawai’i, it is illegal to transport the plant between islands. Seeds, however, are unknowingly carried in tree fern trunks, which are widely shipped from the island of Hawai’i as an ornamental. Plants have been found in several places on Mau’i, indicating that more than one arrival to that island was responsible. It is likely that yellow Himalayan raspberry can be spread to wherever the tree ferns are sold in the state. Seeds can sprout and plants can be found growing directly on the tree ferns. Habitat. Yellow Himalayan raspberry tolerates several types of habitat, from semimoist to moist sites, including wet places in forests and along forest edges, both in full sun and deep shade. In Hawai’i, it is found in open canopy forests, shady rainforests, pasture or rangeland, grassland, agricultural areas, and disturbed sites. The raspberry is found primarily on the wet windward side of Hawai’i and might not be able to tolerate the drier rainshadow sides of the islands. It is especially invasive to areas damaged by feral pigs (see Volume 1, Vertebrates, Mammals, Feral pig). The plant survives in deep shade, taking advantage of forest openings as they occur. It is especially invasive to pasture and forest near Hawai’i Volcanoes National Park at 4,000 ft. (1,200 m). It is found growing at elevations ranging from 2,000 ft. (600 m) to 8,530 ft. (2,600 m), with annual rainfall of 49–275 in. (1,250– 7,000 mm). The plant tolerates some frost. Reproduction and Dispersal. Clumps of yellow Himalayan raspberry brambles increase in size by sprouting stems from root suckers and underground shoots, especially after disturbance by cutting or by fire. Each stem lives two years, producing fruit in the second year and dying two months after flowering. New stands originate from seeds, often when the fruit is eaten by birds and mammals, including humans, and then passed through the digestive tract and deposited in a distant location. Outlying, sporadic populations at mid-elevation forests on the eastern side of the island of Hawai’i are probably due to birds spreading seeds. Seeds can also be accidentally transported in clothing and camping gear, a significant dispersal means in Hawai’i Volcanoes National Park. New plants can also grow from pieces of roots or cuttings of fresh wood not properly disposed of. Impacts. Yellow Himalayan raspberry bushes form impenetrable thickets that displace native vegetation and impede wildlife movement. Arching stems can climb over and smother other plants. Thickets are often several feet or meters wide, and up to 15 ft. (4.5 m) tall. Because it grows in many habitats and smothers smaller plants, the raspberry threatens species diversity in Hawai’i. The native Hawaiian raspberry, akala, has no prickles for protection and is more likely than yellow Himalayan raspberry to be used as forage by feral sheep, goats, and pigs. The plant is considered a major threat to the Ola’a Forest Tract of Hawai’i Volcanoes National Park, especially in areas disturbed by feral pigs. The worst infestation is around farm lots near the town of Volcano and around the summit of Kilauea, where the region receives 50–275 in. (1,270–7,000 mm) of rain annually. Management. Control is not easy. Because of the size of dense thickets and the difficulty of handling the very prickly stems, it is difficult to impossible to eradicate these raspberry plants by physical removal. Every piece of the root must be removed and preferably burned so that it does not have the opportunity to resprout. Physical efforts to eradicate the plant in the Ola’a Forest Tract failed, largely because of the dense thickets where basal stem diameters may exceed 2 in. (5 cm). Even on smaller plants, it is very difficult to extract all the roots. Because yellow Himalayan raspberry is especially invasive to areas disturbed by feral pigs, it is important to first eliminate the pigs. Chemical applications can be applied in several ways, including foliar, stem injection, cut stump, or basal stem. Glyphosate or triclopyr, both systemics, are preferred because the herbicide is transported to the roots. Foliar sprays are not recommended in dense rainforest

YELLOW HIMALAYAN RASPBERRY n 539

Beneficial Uses of Yellow Himalayan Raspberry

C

ontrol of this invasive shrub is made more difficult because the delicious fruits are desirable for food. Fruits are also used to create a natural, purplish blue dye. The inner bark is used as a natural remedy in traditional Tibetan medicine, and the plant is useful as a renal tonic and an antidiuretic.

conditions because they will kill nontarget plants as well as yellow Himalayan raspberry. Experiments conducted at the University of Hawai’i at Manoa indicate that four herbicides (imazapyr, metsulfuron, triclopyr amine, and triclopyr ester) used in cut-stump treatments killed 95–100 percent of yellow Himalayan raspberry plants within two years. Although 10–15 percent resprouted, about one-half later died. Sprouts on plants treated with metsulfuron were slightly more likely to survive. Applications of picloram and 2,4-D + triclopyr killed only 65–75 percent of targeted plants. None of the herbicide applications significantly affected native plants The possibility always exists that any introduction of biological controls might adversely affect native plant species in Hawai’i. Four moths and a sawfly were introduced to control sawtooth blackberry. Not only were they considered to be ineffective, but one species was also observed feeding on the native Hawaiian raspberry species. Results of research attempts specifically to control yellow Himalayan raspberry are not yet available. A possibility exists in plant rust fungi from the southeastern United States.

Selected References Benton, Nancy. “Yellow Himalayan Raspberry.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2009. http://www.nps.gov/ plants/alien/fact/pdf/ruel1.pdf. Hoshovsky, Marc C. “Rubus discolor.” In Invasive Plants of California’s Wildland, edited by Carla C. Bossard, John M. Randall, and Marc C. Hoshovsky. Berkeley: University of California Press, 2000. http://www.cal-ipc.org/ip/management/ipcw/pages/detailreport.cfm@usernumber=71&survey number=182.php. McCarney, Perry. “Invasive Alien Species: Yellow Himalayan Raspberry.” Helium Sciences: Biology, 2002–2010. http://www.helium.com/items/984556-invasive-alien-species-yellow-himalayan -raspberry. Motooka, P., et al. “Rubus ellipticus.” In Weeds of Hawai’i’s Pastures and Natural Areas: An Identification and Management Guide. College of Tropical Agriculture and Human Resources, University of Hawai’i at Manoa, 2003. http://www.ctahr.hawaii.edu/invweed/index.html. Santos, Gregory L., Linda W. Cuddihy, and Charles P. Stone. Control of Yellow Himalayan Raspberry (Rubus ellipticus Sm.) with Cut Stump Herbicide Treatments in Hawaii Volcanoes National Park. Technical Report 80. Cooperative National Park Resources Studies Unit, University of Hawai’i at Manoa, 1991. https://scholarspace.manoa.hawaii.edu/handle/10125/7167. Starr, Forest, Kim Starr, and Lloyd Loope. “Rubus ellipticus, Yellow Himalayan Raspberry.” U.S.Geological Survey, Biological Resources Division. Haleakala Field Station, Mau’i, HI, 2003. http://www.hear.org/starr/hiplants/reports/pdf/rubus_ellipticus.pdf.

n Trees n Australian Pine Also known as: Beach she-oak, casuarina, coast she-oak, ironwood, beefwood, horsetail tree, scaly bark oak, whistling pine Scientific name: Casuarina equisetifolia Synonyms: C. litorea, C. littorea Family: Casuarina (Casuarinaceae) Native Range. Australia and neighboring regions, including Southeast Asia, Indonesia, Borneo, the Philippines, New Guinea, and New Caledonia. Distribution in the United States. California, Arizona, Texas, Alabama, Florida, Hawai’i, Puerto Rico, and the Virgin Islands. Description. Australian pine is an evergreen angiosperm that resembles a conifer because of its needle-like twigs and cone-like fruits. Although it generally grows 50–80 ft. (15–25 m) tall, with an open, irregular crown of erect, spreading, or drooping branches, it can reach as tall as 130 ft. (40 m). Trunk diameter is as much as 1–1.5 ft. (0.3–0.5 m), but those in coppiced thickets are much smaller. Smooth on small trunks, the reddish-brown to gray bark becomes thick, rough, furrowed, and peeling on older trees. What appear to be grayishgreen pine-like needles are narrow jointed twigs, 4–8 in. (10–20 cm) long and less than 0.04 in. (1 mm) wide. The twigs, drooping in clusters, have tiny but distinct ridges running between the nodes (joints). The twigs separate at the nodes, like a horsetail. The leaves are tiny pointed scales, 6–8 gathered in whorls that encircle the joints on the twigs. The needle-like twigs are deciduous, shedding continually all year. Plants have a shallow fibrous root system that spreads near the surface, but roots can also penetrate deep into the soil if moisture is available. Under wet conditions, roots will form a dense mat. Trees are monoecious, meaning that male and female flowers are on the same tree. Many tiny male flowers grow in narrow terminal spikes, 0.25–1 in. (0.6–2.5 cm) long, at the end of the twigs. Female flowers are borne on short stalks in small, round, light-brown clusters further down along the non-shedding part of the branch. Flowers are wind-pollinated. Abundant fruit form in brown woody clusters, or fruiting heads, 0.75 in. (2 cm) long and 0.5 in. (1.3 cm) wide, that resemble pine cones. Green fruiting heads are covered with a mat of white hairs before they ripen and become rusty colored. When the cluster dries, it releases the tiny, 0.25 (6 mm) one-seeded winged nutlets, called samaras. Related or Similar Species. Two other Casuarina species, Australian river oak and Brazilian oak, are also invasive. Both are known by several common names. Australian river oak, the smallest Casuarina in Florida, 33–50 ft. (10–15 m) tall, has a longer male flower spike, 0.4–2 in. (1–5 cm), smaller cones, and 8–10 scaly leaves in a whorl. Because it has no tolerance for salt spray or salt water, it does not grow on beaches. Brazilian oak trees have no female flowers in Florida. This species may be distinguished by its longer deep green twigs, smooth gray branches, and 12–16 scaly leaves in a whorl. In Hawai’i, it has shorter male flower spikes and smaller fruiting heads. Although Australian pine is the only species

AUSTRALIAN PINE n 541

naturalized in the United States, it readily hybridizes with these two species, resulting in trees with intermediate characteristics that are difficult to identify. Introduction History. The U.S. Department of Agriculture introduced seeds of Australian pine to Florida in 1898 for stabilization of ditch and canal banks and for use as shade, shelterbelts, hedges, ornamentals, and timber. The tree became naturalized both in Florida and in the West Indies before 1920. Populations of Australian pine rapidly expanded in 1960 after Hurricane Donna created newly disturbed sites for its establishment. In Hawai’i, plants were recorded on Kaua’i in 1882 and on O’ahu in 1895. Habitat. Australian pine is predominantly found in tropical and subtropical climates in coastal habitats, such as beaches and estuaries, and in riparian sites. It is frequent on disturbed sites, such as filled wetlands, clearings, and roadsides, and can occupy poor soils because it is a nitrogen fixer. Australian pine was used for bank stabilization along canals and ditches The tree has a wide range of in Florida as early as the late 1800s. (Native range approximated from environmental tolerances and USDA GRIN and selected references. Introduced range adapted from can grow on several types of USDA PLANTS Database, Invasive Plant Atlas of the United States, and substrate, including sand or selected references.) shell beaches, rocky coasts, sand bars or sand dunes, and on limestone. It can withstand partial water logging and can live in slightly saline mangrove habitats, but does not do well in heavy, clay soils. In Florida, Australian pine is usually found in coastal swamps or in hammocks in the Everglades, where it is salt tolerant and wind resistant. The mean maximum monthly temperature in its native range is 50–91ºF (10–33ºC), and it is not frost hardy. Average annual rainfall in its native range is 28–79 in. (700–2,000 mm), often with a six- to eight-month dry season, but it can grow with as little as 25 in. (640 mm) or as much as 169 in. (4,300 mm) of annual rainfall. It can also grow in semiarid regions and from sea level to approximately 5,000 ft. (1,500 m) elevation. In their native Australia, Australian pine grows along the coast, Brazilian oak grows in swamps, and Australian river oak grows along rivers. In Florida, Australian pine is more

542 n TREES

A. The forest floor under an Australian pine stand is barren of other plants. (Forest and Kim Starr, U.S. Geological Survey, Bugwood.org.) B. What appear to be needles are twigs with scaly leaves. (Amy Ferriter, State of Idaho, Bugwood.org.) C. Cone-like fruit form in brown woody clusters. (Forest and Kim Starr, U.S. Geological Survey, Bugwood.org.)

frequent along beaches and other dry sites, while Brazilian oak, the most frost hardy, is found along roads and fence lines. Australian river oak is primarily limited to deliberately planted trees. In Hawai’i, Australian pine is found along the sandy coast and other lowlands. Reproduction and Dispersal. Except for Brazilian oak, which has no female flowers in Florida, Casuarina species reproduce both sexually and vegetatively. Although trees in Hawai’i and Puerto Rico can produce flowers and fruit year-round, most trees in the United States flower twice a year, February to April and September to October. Fruit matures in June and December. After reaching 4–5 years of age, each plant produces thousands of winged seeds. Seeds are dispersed by birds, animals, water, and wind. Birds, particularly exotic parrots and parakeets, eat the seeds, and seeds may also adhere to animals’ feet and fur. The fruiting heads float in rivers and currents, and the wings on the seeds enable them to be wind-blown. Although seeds need only 4–8 days to germinate under ideal conditions, they remain viable for as long as a year. Seedlings, sensitive to fire, drought, and flooding, grow most rapidly in the first seven years, as much as 6.5 ft. (2 m) in the first year alone. Growth rates in Florida vary with conditions, ranging from 1.6 ft. (0.5 m) to over 10 ft. (3 m) per year. The plant, however, is intolerant of shade, and seedlings can easily be outcompeted by grasses and sedges. When the trunk of Australian pine or Brazilian oak is cut, it will produce many sprouts from the stump, resulting in a thicket of small trees. Brazilian oak also produces many new trees from root suckers, even without injury, but Australian pine and Australian river oak do not. Impacts. Australian pine alters the habitat, displaces native species, and contributes to soil erosion. Dense, monospecific thickets alter the light, temperature, soil chemistry, and hydrology of the habitat, which displaces native dune and beach plant species. Growing quickly to produce heavy shade, Australian pine also depletes soil moisture and lowers the water table. The thick litter layer has alleleopathic properties, which inhibit the growth of other plants. It offers little to no wildlife habitat, displacing native songbirds except for migrating goldfinches, which eat the seeds. The twigs and foliage have little food value, and the thick litter layer covering the ground does not favor insect populations. In the Everglades, fewer rodents, such as cotton mouse, hispid cotton rat, and marsh rice rat, inhabit groves of

AUSTRALIAN PINE n 543

Australian pine. Rodents are an important ecological link between plants and predators, such as raptors and snakes. Australian pine destroys breeding sites of threatened or endangered species in the Everglades, particularly the only remaining nesting sites in the United States of the American crocodile. Because baby turtles get trapped in the maze of tree roots, the most productive nesting sites for the green sea turtle and loggerhead turtle are at risk. The gopher tortoise is also vulnerable. The trees have a shallow root system, providing little support in storms. Downed Australian pine trees blocked escape routes in Florida after a 1945 hurricane. The root system can also break sewer and water lines and crack pavement. Because Australian pine displaces soil-binding vegetation, erosion is more likely to occur. The tall trees do not trap sand as well as shorter plants, resulting in flatter topography instead of the diversity in habitat provided by a swell and swale system. The pollen causes significant respiratory allergic reactions. Management. Most physical means of removal are ineffective because cutting or damage to the tree induces sprouting. Small stands may be removed by digging out seedlings and small trees. Periodic burning of large monospecific stands, combined with herbicide use on resprouts, may be used for trees greater than 3 in. (8 cm) in diameter. However, fire can also make the soil too alkaline, rendering it unsuitable for native plant species. Applied in any method—basal bark, cut stumps, hack-and-squirt, spray, or injection— chemical treatments are effective. Triclopyr works well on foliage of shoots and saplings. Glyphosate, dicamba, and picloram are best for cut surfaces. Although Australian pine is a tree with few insect problems, searches are being conducted for biological agents. No natural enemies exist in North America. A twig girdler (Oncideres cingulata) and an Australian pine borer (Chrysobothris tranquebarica) are only effective on small trees. Both a leaf notcher weevil (Artipus floridanus) and a spittlebug (Clastoptera undula) do little damage. Tests are being conducted on a defoliating moth (Zauclophora pelodes) and a host-specific seed-feeding wasp (Bootanelleus orientalis). Pests that attack trees in plantation settings or other places in Australian pine’s introduced range throughout the world also deserve notice. In India, a stem borer kills shoots, and a Rhizoctonia species causes seedling damping off. A root fungus (Trichosporium visiculosum) causes a blister disease in India, especially in wet, crowded conditions. A lymantriid moth (Lymantria xylina) is a significant pest of both Australian pine and Brazilian oak in China. A root rot is caused by a fungus (Clitocybe tabescens) in Florida, but it also attacks 210 other species. A stem canker and dieback is caused by a fungus (Diplodia natalensis) in Puerto Rico. Puerto Rico and India see few seedlings because of predation of seeds by ants.

Uses of Australian Pine

A

ustralian pine is widely used in regions where it has been introduced, especially in developing countries. Because of its rapid growth, it is often used for coastal reclamation and erosion control. Although brittle, the wood has a variety of uses, including oars, paving, wheels, roofing, and boats. The tannin has been used to cure alligator skins in Florida. In Hawai’i, the hard wood was used for war clubs and for beaters to pound tapa cloth, but now is used primarily for fuel.

544 n TREES

Selected References Elfers, Susan C. “ Element Stewardship Abstract, Casuarina equisetifolia.” Global Invasive Species Team, Nature Conservancy, 1988. http://wiki.bugwood.org/Casuarina_equisetifolia “Horsetail Casuarina.” In Common Forest Trees of Hawaii (Native and Introduced). Agricultural Handbook No. 679 by Elbert L. Little Jr. and Roger G. Skolmen. U.S. Department of Agriculture, Forest Service, 1989. Reprint by College of Tropical Agriculture and Human Resources, University of Hawai’i at Manoa, 2003. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Casuarina equisetifolia (Tree).” ISSG Global Invasive Species Database, 2010. http:// www.issg.org/database/species/ecology.asp?fr=1&si=365. “River-oak Casuarina.” In: Common Forest Trees of Hawaii (Native and Introduced). Agricultural Handbook No. 679 by Elbert L. Little Jr. and Roger G. Skolmen. USDA Forest Service. 1989. Reprint by College of Tropical Agriculture and Human Resources, University of Hawai’i at Manoa, 2003. Rockwood, D. L., R. F. Fisher, L. F. Conde, and J. B. Huffman. “Casuarina.” n.d. http://www.na.fs.fed .us/pubs/silvics_manual/volume_2/casuarina/casaurina.htm.

n Brazilian Peppertree Also known as: Christmasberry, Florida holly, Pimienta de Brazil, copal, schinus, wilelaiki Scientific name: Schinus terebinthifolius Synonyms: Sarcotheca bahiensis, Schinus antiarthriticus, Schinus mellisii, Schinus mucronulatus, Rhus terebinthifolia Family: Sumac (Anacardaceae) Native Range. Southern Paraguay, northeastern Argentina, Uruguay, and southeastern Brazil. Distribution in the United States. Widespread use as an ornamental in tropical, Mediterranean, and desert climates of California, Texas, Florida, Alabama, and Hawai’i, as well as Puerto Rico and the Virgin Islands. It has not reached the limits of its potential range, and is invasive in Hawai’i and Florida. Description. Brazilian peppertree grows either as a small broadleaf evergreen tree, usually 6.5–23 ft. (2–7 m) tall, or as a shrub. The trunk can be as large as 3 ft. (1 m) in diameter, but hidden by densely intertwining and arching branches. Shrubby trees with multiple trunks occur when many stems sprout from the root. The slightly rough bark is gray or dark, but young stems are yellow-green. The resinous sap and crushed leaves are aromatic, with a turpentine or peppery smell. Alternate leaves are pinnately compound, shiny and dark green above and pale green below. The number and size of leaflets is variable, ranging from as few as 4 to as many as 13. Leaflets are elliptical and pointed at each end. They can be as small as 0.6 in. (1.5 cm) or as large as 3 in. (7.5 cm) long and 1.25 in. (3 cm) wide, with the terminal leaflet being the largest. Leaves have a reddish color, often with a reddish midrib, and may be either entire or finely toothed. Distinctive parallel veins pattern the leaflets from the midrib. Trees flower in the fall, September through November, followed by the fruit from December to February. About 10 percent of populations flower again in spring, March to May. Flower clusters, 2–3 in. (5–7.5 cm) long, consisting of several small greenish-white flowers with yellow petals and yellow centers, grow in the leaf axils near the ends of branches. Although male and female flowers are not distinctively different, they occur on separate male and female trees. Male flowers last only one day, while female flowers last

BRAZILIAN PEPPERTREE n 545

up to six days. Flowers are pollinated by many insects, especially flies, wasps, and butterflies. Female trees produce an abundance of fruit, which remains ripe on the tree for eight months. Occurring in clusters like the flowers, the fruits are small, 0.16–0.25 in. (4–6 mm), glossy green berries which turn red when ripe. They have a brown pulp. Seeds are dark brown and tiny, one in each berry. A pound contains over 36,500 seeds (80,600 per kg). Related or Similar Species. Peruvian peppertree, also called California peppertree, can be distinguished by its weeping foliage and hanging flower panicles, almost a foot long (30 cm). The pale yellow flowers are followed by long, hanging clusters of green berries, first turning red, and then black as they ripen. The long compound leaves have 20–40 leaflets. The bark is dark brown and deeply fissured, peeling off in large flake-like plates. This species is also becoming inva- Commonly planted as an ornamental or for shade in California and sive in some areas. southern states, Brazilian peppertree is still expanding its range. (Native Introduction History. Listed range adapted from USDA GRIN and selected references. Introduced in seed catalogs as an ornamen- range adapted from USDA PLANTS Database, Invasive Plant Atlas of the tal in 1832, Brazilian pepper- United States, and selected references.) tree was imported to Florida by the 1840s. In the mid-1920s, a gardener gave friends hundreds of seeds, which dispersed the plant around the state. By the 1950s, the tree was considered an invasive pest. By 1969, it had reached the Everglades. It is still planted as an ornamental tree in several states. Habitat. Brazilian peppertree invades disturbed sites, such as fields, ditches, roadsides, and drained wetlands. It also invades pinelands and grows densely in dry to mesic pastures and forests, as well as in urban environments. In Florida, trees can dominate some hammocks, pinelands, and mangrove forests. In Hawai’i, it is widespread in mesic to dry environments, and can be dense on wastelands. It is very drought resistant and can survive both fire and high winds. Brazilian peppertree is a pioneer species and does not invade well-established native ground cover, but once it gains a foothold, the trees grow fast and outcompete native plants. It is tolerant of partial shade, growing slowly beneath a canopy

546 n TREES

A. The trunk of large trees may be hidden unless low-hanging branches are pruned. (Forest and Kim Starr, U.S. Geological Survey, Bugwood.org.) B. Flower clusters grow from leaf axils. (James H. Miller, USDA Forest Service, Bugwood.org.) C. Compound leaves have elliptical leaflets. Fruits are glossy red berries. (Joseph M. DiTomaso, University of California-Davis, Bugwood.org.)

until some disturbance opens the site to vigorous growth. It is somewhat tolerant of salinity, invading mangrove regions and low-saline ditches. Although seedlings die in deep water, mature trees can withstand up to six months of flooding. It is absent, however, from the parts of the Everglades that are flooded for more than six months. Its northern spread is limited because it cannot survive cold temperatures. Reproduction and Dispersal. The invasive nature of Brazilian peppertree is enhanced by its tremendous seed production, effective dispersal, and high germination rate. Trees mature in 3 years and can live for more than 30 years. Birds and mammals spread the seeds, and birds are critical in removing the fruit pulp. Because germination is improved by scarification, seeds benefit from the digestive tracts of birds and mammals. Raccoons and opossums especially feed on Brazilian peppertree seeds, and sometimes their droppings contain hundreds of germinating seeds. Seeds are also dispersed by water. Between 30 and 60 percent of the seeds are viable, but for only 2–9 months. Most germination takes place in January and February, soon after the fruit ripens. Between 66 and 100 percent of seedlings survive. The plant also propagates by resprouting from roots and from cuttings. Impacts. Brazilian peppertree’s major threat is to biodiversity of both plants and animals. Capable of invading both terrestrial and seasonally aquatic environments, it grows in dense thickets that shade out native plants and dominate pine forests. It replaces functioning ecosystems with dense, monotypic stands, decreasing habitat for native wildlife. Brazilian peppertree has displaced local populations in Florida of federally endangered species, such as beach clustervine and the endangered sedge, beachstar. Compared with native pinelands,

U.S. Champion

T

he largest Brazilian peppertree in the United States, 52.75 in. (134 cm) in diameter at breast height and 35 ft. (10.7 m) tall, is in Florida.

Source: John K. Francis, U.S. Department of Agriculture, Forest Service, International Institute of Tropical Forestry, San Juan, PR. N.d.

BRAZILIAN PEPPERTREE n 547

Brazilian peppertree stands have smaller populations and lower diversity of birds. Based on chemical irritants of its sap and leaves, the tree is suspected of allelopathy, but no field evidence exists to prove so. Because it is in the same family as poison ivy, poison oak, and poison sumac, contact with the sap or leaves can cause a rash in persons with sensitivity. Pollen can cause respiratory problems, as can smoke from burning plants. If eaten in excess, berries and seeds can kill raccoons, deer, and horses. Considered one of the most aggressive trees in Florida, Brazilian peppertree infested an estimated 113,500 ac. (280,000 ha) in central and southern Florida in the mid-1990s. A negative effect on tourism is expected as Brazilian peppertree replaces more of the natural ecosystems visitors come to see. Visitors may also choose to avoid areas where the tree is common, therefore eliminating risk of resin-caused dermatitis. Management. The best management strategy is to not grow Brazilian peppertree as an ornamental or allow it to be sold or transferred. Cut trees must be disposed of properly to prevent inadvertent seed dispersal. Because seeds are viable for a short time and no substantial seed bank remains in the soil, it is possible to totally eradicate small stands. Female trees can be selectively removed, therefore eliminating seed production. Physical control is possible if the entire plant, especially the roots, is removed. Even small root pieces, 0.25 in. (0.6 cm) diameter, can sprout. Fire will kill the aerial parts, but not the roots, which will produce new shoots. Seeds, however, will not germinate after a fire. Browsing by goats will control Brazilian peppertree but will not kill it. Foliar applications of herbicides are an effective chemical control, but coverage is difficult with large, leafy stands. The technique is better used for seedlings. Triclopyr or glyphosate leave no soil residuals, so nontarget plants are not harmed unless their leaves are accidentally sprayed. Imazapyr is also good, but because it has more soil residual, it harms nontarget species. Glyphosate or triclopyr can also be applied to trunks that are freshly cut. Triclopyr, with an oil additive that enables it to penetrate the bark and take the herbicide down to the cambium, can be wiped on basal bark with no need to first girdle the tree. This method requires weeks to take effect, but defoliation and termite activity are clues that it has worked. Trials with 2,4-D were not effective. Several herbicides, such as bromacil and hexazinone, which remain in the soil, are absorbed by tree roots and provide long-term effectiveness. They are slow to act, however, and a problem for nontarget species of hardwoods such as oaks and maples, which also absorb the herbicides from the soil. Although more than 200 insects feed on Brazilian peppertree in its native range, no biological controls for North America are currently known. Three Brazilian species were

Beneficial Uses of Brazilian Peppertree

B

ecause it is fire-resistant, Brazilian peppertree has been planted for fire breaks. Although the wood is too brittle for lumber, it is useful for stakes and posts. The abundant nectar supplies honey bees, and the foliage and twigs can be browsed by goats. The bright red berry clusters are used as Christmas decorations. Dried fruits are used in Brazil as a substitute for black pepper. The bark, when steeped in a hot bath, is used as a folk remedy in South America to cure rheumatism and back pain. Other folk remedies include use for skin ulcers, bronchitis, gout, arthritis, diarrhea, and infertility.

548 n TREES released in Hawai’i—a seed-feeding beetle (Lithraeus atronotatus = Bruchus atronotatus), a leaf-rolling moth (Episimus utilis), and a stem-galling moth (Crasimorpha infuscata). Two did only minor damage, and one failed to establish. A species of wasp (Megastigmus transvaalensis) originally from South Africa, was accidentally introduced into both Hawai’i and Florida, where it was found feeding on Brazilian peppertree fruit. It appears to kill up to 80 percent of the seeds it attacks, giving this wasp good potential for control. A sawfly (Heteroperreyia hubrichi) which causes defoliation; a thrips (Pseudophilothrips ichini), which attacks the roots; and other insects are being studied as possibilities.

Selected References Cuda, J. P., J. C. Medal, and D. H. Habeck. “Classical Biological Control of Brazilian Peppertree (Schinus terebinthifolius) in Florida.” ENY-820 (IN114). University of Florida Institute of Food and Agricultural Science (IFAS) Extension, 1999; revised 2009. http://edis.ifas.ufl.edu/in114. Hight, S. D., J. P. Cuda, and J. C. Medal. “Brazilian Peppertree.” In Biological Control of Invasive Plants in the Eastern United States, by R. Van Driesche et al. USDA Forest Service Publication FHTET-200204, 2002. http://www.invasive.org/eastern/biocontrol/24BrazilianPeppertree.html. MacDonald, Greg, Brent Sellers, Ken Langeland, Tina Duperron-Bond, and Eileen Ketterer-Guest. “Brazilian Pepper-tree, Schinus terebinthifolius.” Excerpted from the University of Florida Institute of Food and Agricultural Science (IFAS) Extension, Circular 1529, Invasive Species Management Plans for Florida. Center for Aquatic and Invasive Plants, 2008. http://plants.ifas.ufl.edu/node/405. Masterson, J. “Schinus terebinthifolius (Brazilian Pepper).” Smithsonian Marine Station at Fort Pierce, FL, 2007. http://www.sms.si.edu/irlspec/Schinus_terebinthifolius.htm. Motooka, P., et al. “Schinus terebinthifolius.” In Weeds of Hawai’i’s Pastures and Natural Areas; An Identification and Management Guide. College of Tropical Agriculture and Human Resources, University of Hawai’i at Manoa, 2003.

n Carrotwood Also known as: Tuckeroo tree, carrot weed. Scientific name: Cupaniopsis anacardioides Synonyms: Cupania anacardioides, Cupania anacardioides var. parvifolia Family: Soapberry (Sapindaceae) Native Range. North and east coasts of Australia and New Guinea. Distribution in the United States. Carrotwood is a popular landscape tree that is very adaptable and widely planted. It has become naturalized on both east and west coasts of Florida. In 1996, its distribution paralleled that of mangroves, and inland populations were just beginning to develop. Also in California, Texas, and Hawai’i. Description. Carrotwood is a broadleaf evergreen tree, usually with one slender trunk, which may rapidly grow as tall as 35 ft. (10.5 m). The outer bark is dark gray, but the inner bark, which gives the tree its name, is orange-colored. The large compound leaves, alternate on the stem, are evenly pinnate, meaning that the leaf terminates in a pair of leaflets. The petioles have a swollen base. The 4–12 stalked leaflets are a shiny oblong, yellowish green, and leathery. They are 8 in. (20 cm) long and 3 in. (7.5 cm) wide, with untoothed but wavy margins, and tips that are rounded or slightly indented. From January to March, depending on locality, many inconspicuous flowers grow in branched clusters from leaf axils. Each cluster is 3–14 in. (7.5–35.5 cm) long. Although flowers are unisexual, both types occur in each cluster. The small flowers, with five white to greenish petals less than 0.1 in. (3 mm) long, grow on short pedicels. Male flowers have

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eight stamems. Fruit, on a shortstalk, is a woody capsule, about 1 in. (2.5 cm) in diameter, with three distinctly ridged segments or lobes. Both flowers and fruit are minutely pubescent. The capsule ripens to yellow in April to June, before drying to a brown color and splitting to reveal the seeds. Three shiny black seeds in each fruit are covered by a red-orange aril, or fleshy tissue. Related or Similar Species. The unusual fruit and color of the wood make this tree distinctive. Introduction History. Carrotwood was brought to St. Lucie County in eastern Florida in 1955 as a cultivated plant. In 1968, a separate commercial introduction placed the plant into large-scale propagation as an ornamental in Sarasota. It was a popular landscape plant in the late 1970s and the early 1980s, but by 1990, seedlings were found in various natural habitats. Carrotwood was recommended as a street tree in Honolulu. Habitat. Carrotwood is a very Especially popular as an ornamental tree in Florida, carrotwood is durable urban tree that is used in tolerant of saline conditions and poor soils. (Native range adapted from private gardens and commercial USDA GRIN and selected references. Introduced range adapted from landscaping. It occupies dis- USDA PLANTS Database, Invasive Plant Atlas of the United States, and turbed and undisturbed sites in selected references.) both herbaceous and scrub communities. Growing in both sun and shade, it can tolerate conditions of salt, nutrient-poor soils, and poor drainage. Although most common in wet locations, such as freshwater marshes and riverbanks, it has a wide range of tolerance to soil moisture and can also be found in dry sites, such as hammocks and pinelands. Its tolerance of salinity enables it to invade coastal habitats, including mangrove and cypress swamps, beach dunes, and coastal strands. Cold temperatures, approximately 22ºF (-6ºC), may be the limiting factor in the potential northward distribution of carrotwood. Although used as an ornamental plant in California, no reports have indicated that carrotwood is becoming naturalized, probably because of California’s drier climate. Reproduction and Dispersal. Carrotwood reproduces both sexually and vegetatively, but it spreads primarily by seed. Flowers are most likely pollinated by bees. Plants seed freely,

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A. Carrotwood trees usually have a single trunk. B. Large compound leaves are leathery, with shiny oblong leaflets. C. Fruits are woody capsules. D. Each capsule has three compartments or segments. E. The hard seeds have a distinctive red aril. (Forest and Kim Starr.)

and the seeds are attractive to birds. Populations beneath telephone poles and lines, as well as island populations, can be attributed to birds. Fish Crows in Florida are especially important in carrying seeds from inland to coastal island habitats. Clumps of seedlings, however, are more likely the result of small mammals, which gather the fruit. Seeds are also distributed by water. When the top part of the tree is damaged or cut, multiple sprouts emerge from the stump. If left unpruned, the result is a multi-trunked tree. Impacts. Carrotwood is especially a problem in low, moist areas and a significant pest in mangrove habitats, which are important biological resource areas. Mangrove swamps are critical sites for wading and diving birds and provide protected nursery habitat for commercial and sport fish, crabs and other crustaceans, and invertebrates. These important habitats, as well as coastal hammocks, are in jeopardy because they are also removed from the natural landscape by development and by tropical storms and hurricanes. Carrotwood can develop monotypic stands in mangrove and coastal hammock sites, with densities of more than two plants per square foot (20 per m2). In Hawai’i, carrotwood grows in dense monocultures, crowding and outcompeting native plants for light and nutrients. Carrotwood also grows with other invasive plants in Hawai’i. Management. Because carrotwood is a common landscape plant, many management suggestions are directed to private homeowners. A major goal is to prevent distribution or dispersal of seeds. Physical prevention of seed development includes removing mature landscape plants. After cutting close to the ground, the stump should be treated with herbicides to prevent resprouting. Dead trees may be left in place to decay. Chemical treatments, which include triclopyr or glyphosate, are the most commonly used and most effective controls of carrotwood. Triclopyr is the best application for basal bark or to cut stumps. Glyphosate has marginal effectiveness, and treatments usually need to be repeated. Any applications of herbicides in mangrove swamps or other wetlands must be made with care because of the sensitivity of those water environments. No biological controls are known for carrotwood.

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Selected References Langeland, K. A. “Natural Area Weeds: Carrotwood (Cupaniopsis anacardiodes).” SS-AGR-165. University of Florida Institute of Food and Agricultural Sciences (IFAS) Extension, 2001; revised 2009. http://edis.ifas.ufl.edu/ag111. Lockhart, Chris. “Carrotwood (Cupaniopsis anacardioides).” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance, Alien Plant Working Group, 2009. http:// www.nps.gov/plants/alien/fact/cuan1.htm. National Biological Information Infrastructure (NBII) and IUCN/SSC Invasive Species Specialist Group (ISSG). “Cupaniopsis anacardioides (Tree).” ISSG Global Invasive Species Database, 2005. http:// www.issg.org/database/species/ecology.asp?si=641.

n Chinaberry Also known as: Pride of India, umbrellatree, Persian lilac, Indian lilac, white cedar, China tree, bead tree, ‘inia (Hawai’i), alelaila or pasilla (Puerto Rico) Scientific name: Melia azedarach Synonyms: Melia japonica, Azedarach amena, A. sempervirens, A. vulgaris, Melia angustifolia, M. australasica, M. floribunda, and others. Family: Mahogany (Meliaceae) Native Range. Temperate and tropical southeastern China, possibly India and Southeast Asia. Naturalized in Japan, India, Sri Lanka, Indonesia, Papua New Guinea, northern Australia, and the Solomon Islands. Distribution in the United States. Southern half of the United States, from California to Florida, north to Utah, Missouri, Virginia, and New York. Also in Hawai’i, Puerto Rico, and the Virgin Islands. Description. Chinaberry is a fast-growing deciduous tree usually less than 30 ft. (10 m) tall, although some plants reach 50 ft. (15 m) in height. Its rounded crown may cover an area 20 ft. (6 m) in diameter, making it a desirable shade tree. Although a single trunk may be as thick as 2 ft. (0.6 m) in diameter, the tree often has many smaller trunks because it readily sprouts from its roots. Stout stems and twigs, ranging in color from glossy olivegreen to brown or slightly purplish red, are covered with light brown spots. Leaf scars from dropped leaves are three-lobed and prominent. The bark, either dark chocolate or reddish brown, is also covered with light-brown spots, lenticels, and becomes fissured with age. The wood is soft and white. The bipinnately, or sometimes tripinnately, compound leaves, 1–2 ft. (0.3–0.6 m) long and 9–16 in. (23–41 cm) wide, give the tree a lacy appearance. Leaves are alternate, on long petioles, and either glabrous or covered with very fine hairs. They emit a musky odor when crushed. Toothed leaflets are lance-shaped, 1–3 in. (2.5–8 cm) long and 0.5–1.2 in. (1.3–3 cm) wide, tapering towards the tip. The upper surface of leaflets is dark green, with a sparsely hairy light-green midvein. The lower surface is a lighter green with no hairs. Leaves turn golden yellow in the fall. The root system is shallow, within the top 28 in. (70 cm) of the soil. In early spring, from March through May, loose drooping clusters of small fragrant flowers emerge in leaf axils on the new growth toward the ends of the branches. Each starshaped flower, with five narrow pink or lavender petals around a central dark tube, is about 0.75 in. (2 cm) in diameter. Round yellowish-tan berries, about the same size as the flowers and also hanging in clusters, are initially mucilaginous and sticky, but become leathery,

552 n TREES brown seed capsules when mature. The hard berries, each containing 1–6 seeds, remain on the tree after the leaves fall. Related or Similar Species. Texas umbrella chinaberry, also called Texas umbrella tree, is characterized by upward arching branches and drooping foliage that resembles an umbrella. This variety is often pollarded (limbs cut back to trunk), causing a dense cluster of branches to sprout from the top of the pruned tree. Common elderberry, a native shrub, can be distinguished by its white flowers and dark purple berries. Introduction History. The precise time period when Chinaberry was introduced to the United States is not clear. It may have been brought to the United States in the late 1700s by a French botanist, or introduced to Charleston, South Carolina, or Georgia in the mid-1800s. It has been a popular ornamental shade tree in southern states for over 200 years, where it is believed Chinaberry has been a popular shade tree in the southern states for over to bring good luck. It was intro200 years. (Native range adapted from USDA GRIN and selected duced as an ornamental to references. Introduced range adapted from USDA PLANTS Database, Hawai’i in 1840. The tree is still Invasive Plant Atlas of the United States, and selected references.) sold in nurseries. Habitat. Chinaberry can grow in a variety of habitats, but is most invasive in riparian zones or disturbed sites. Usually found below 1,000 ft. (300 m) elevation, it is reported to grow as high as 9,000 ft. (2,700 m) elevation in Hawai’i. The tree most often invades disturbed areas, such as road right-of-ways, fencerows, forest margins, and open areas, or after a site has been burned, cleared, or mowed. However, it is also found in relatively undisturbed sites, such as floodplain hammocks, marshes, and upland woods and grasslands. It is frequently found in open pine forests in South Carolina when fires are suppressed and after eradication of other invasive species, such as kudzu. It is often present around rural home sites, both occupied and abandoned, in the southeastern states. In Hawai’i, Chinaberry invades dry pastures and both dry and moist forests. It tolerates a wide range of soil moisture, as well as heat, drought, and poor soils. It grows most vigorously in full sun and is only somewhat shade tolerant. Although predominantly a tropical or subtropical species, the tree tolerates some frost.

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A. Trees have a rounded crown. (Chuck Bargeron, University of Georgia, Bugwood.org.) B. Compound leaves give the tree a lacy look. (Karan A. Rawlins, University of Georgia, Bugwood.org.) C. Star-shaped flowers are small. (Chris Evans, River to River CWMA, Bugwood.org.) D. Old bark becomes fissured. (Karan A. Rawlins, University of Georgia, Bugwood.org.) E. Berries hang in clusters. (Cheryl McCormick, University of Florida, Bugwood.org.) F. Bark on twigs and young trunks is speckled with lenticels. (James H. Miller, USDA Forest Service, Bugwood.org.)

Reproduction and Dispersal. Chinaberry reproduces and spreads both by seed and by vegetative means. Plants produce abundant seed, which can be carried long distances by birds or downstream by water in riparian areas. Because seeds require no dormancy period and can germinate as soon as they mature, seedlings are numerous. Seeds can survive severe desiccation and remain viable for at least two years. Colonies of trees sprouting from rootstocks can create dense, monotypic thickets. Impacts. Plants grow rapidly from numerous root sprouts to create dense thickets that crowd out and shade out native species. Plants can reach a height of 19.5–26 ft. (6–8 m) in only 4–5 years. By creating monocultures, Chinaberry decreases the biodiversity in native ecosystems. Because Chinaberry is resistant to insects and pathogens, it is able to outcompete native plants. The plant also has alleleopathic properties. The leaf litter changes the chemistry of the soil, reducing the aluminum levels and making the soil more alkaline. Leaf litter can also increase the available nitrogen, comparable to nitrogen-fixing legumes. The wood is brittle, and large trees are prone to dropping limbs, posing a hazard to people and structures. All parts of the plant, especially the fruit, are poisonous to humans, some livestock, and small mammals, including cats and dogs. Symptoms, which appear a few hours after ingestion, include stomach irritation, vomiting, diarrhea, breathing difficulty, and weakness or paralysis. Cattle and some birds usually eat the fruit without harm. However, ingestion of too many seeds may paralyze birds. Bees and butterflies do not use the flowers. Management. Maintenance of a healthy ecosystem, combined with early detection and control, will prevent Chinaberry invasions in natural areas. Where plants have become firmly established, total eradication is unlikely. The best management for existing Chinaberry trees is to limit or prevent seed production. Sites should be monitored for new growth and potential seed production for 3–5 years. Chinaberry can be identified on color-infrared aerial photographs, a factor that is useful for documenting its spread or for monitoring control efforts. Physical methods of controlling chinaberry, such as

554 n TREES

Uses of Chinaberry

T

he hard berries of Chinaberry trees are used for beads and in rosaries. Fruit and leaves can be used like mothballs to prevent insect damage to clothing or books. When stored with food, leaves act as an insect repellant. Extracts of the bark and fruit have medicinal properties and have been used for many purposes, such as an antiseptic, an emetic, a diuretic, and an astringent. Parts of the plant are reputed to reduce fevers, treat rheumatism, and kill parasitic roundworms. A peptide from leaf tissue has been shown to be effective against the herpes simplex virus.

hand-pulling, are only effective on very small seedlings. Because plants vigorously resprout from root fragments, all parts of the root must be removed. Cutting or mowing down trees will prevent development of seeds, but herbicides should be applied to the sprouts to prevent formation of thickets of trees. Chemical applications are the most effective means of controlling Chinaberry. Seedlings and small trees can be killed by spraying foliage with triclopyr, glyphosate, or imazapyr, but root systems of larger trees will not be affected. Foliar sprays are best done in summer and fall. Spraying trees taller than 20 ft. (6 m) or large stands is not practical because of the amount of foliage to be covered. Herbicides, such as imazapyr, picloram, or triclopyr, applied to cut stumps or girdled trunks are the best approach for large trees. This technique does best in late summer and fall, when the trees are translocating nutrients to the roots. Basal bark or cut stump application of triclopyr has proven to be most effective method of eradication. Because Chinaberry is practically insect and disease free, no biological controls are known.

Selected References Batcher, Michael S. “Element Stewardship Abstract, Melia azedarach, Chinaberry, Umbrella Tree.” Global Invasive Species Team, Nature Conservancy, 2000. http://www.imapinvasives.org/GIST/ ESA/esapages/documnts/meliaze.pdf. Motooka, P., L. Castro, D. Nelson, G. Nagai, and L. Ching. “Melia azedarach.” Weeds of Hawai’i’s Pastures and Natural Areas: An Identification and Management Guide. College of Tropical Agriculture and Human Resources, University of Hawai’i, Manoa, 2003. http://www.ctahr.hawaii.edu/invweed/WeedsHI/W_Melia_azedarach.pdf. Reemts, Charlotte. “Chinaberry (Melia azedarach).” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2009. http://www.nps.gov/plants/ alien/fact/meaz1.htm. Scheper, Jack. “Melia azedarach.” Floridata, 1999; updated 2004. http://www.floridata.com/ref/M/ meli_aze.cfm.

n Fire Tree Also known as: Firetree, fayatree, faya bush, candleberry myrtle, firebush Scientific name: Morella faya Synonyms: Myrica faya Family: Sweet Gale (Myricaceae)

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Native Range. Azores, Madeira Islands, Canary Islands. Distribution in the United States. All major islands in Hawai’i. In the late 1980s, it covered 100,000 ac. (40,470 ha), and it continues to expand its range. Description. Fire tree is an evergreen shrub or small tree, usually growing 12–26 ft. (3.7–8 m) tall, although it has been documented at 50 ft. (15 m). Stems and branches are covered with hairs. The dark green leaves are oblanceolate, 2–4 in. (5–10 cm) long and slightly less than an inch (2–2.5 cm) wide They are wider toward the tip than at the base. Alternate on the stem, the aromatic leaves are leathery, shiny, and smooth, but covered with inconspicuous brownish glandular dots. Leaf margins are entire or with shallow serrations toward the apex. The species is subdioecious, meaning that both male and female trees have a few flowers of the opposite sex. Tiny flowers develop among the current As a nitrogen fixer, fire tree colonizes nutrient-poor cinder and ash year’s growth of leaves. Flowers deposits on Hawaiian volcanoes, altering the successional process. have no calyx or corolla and (Native range adapted from USDA GRIN and selected references. grow in many-branched cat- Introduced range adapted from USDA PLANTS Database, Invasive Plant kins. Catkins with yellow- Atlas of the United States, and selected references.) green male flowers, each with four pinkish stamens, occur in small, hanging clusters near the ends of branches. Female flowers, hanging in clusters of three, grow further down on the branches. Plants produce an abundance of small edible fruit, bumpy looking like berries about 0.25 in. (6 mm) in diameter. Fruit is red to blackish-purple when it ripens in June. Related or Similar Species. None in Hawai’i. Introduction History. Fire tree was introduced to Hawai’i in the late 1800s by Portuguese immigrants, probably as an ornamental, for medicinal purposes, or for firewood. They also made a wine from the berries. In the early 1900s, trees were planted in reforestation projects, but by 1937, the species was recognized as invasive. The first eradication attempts followed in 1944. Fire tree was first discovered in Hawai’i Volcanoes National Park in 1961. By 1977, plants covered approximately 30,000 ac. (12,200 ha) in that park, and approximately 85,000 ac. (34,400 ha) on the island group.

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A. Trees usually grow 25 ft. (7.5 m) tall. B. Leathery leaves are shiny and smooth. C. Male catkins grow near the ends of branches. D. Fruit are bumpy looking berries. (Forest and Kim Starr.)

Habitat. Occupying a wide variety of habitats, fire tree invades various types of native forest, shrublands, agricultural areas, pastures, roadsides, and steep slopes. Because it is a nitrogen fixer, fire tree is capable of invading newly developed, nutrient-poor volcanic cinders and ash. It grows on recent cinder deposits, thin ash over lava, as well as on welldeveloped silty, clay, or loam soils. It forms dense, monotypic stands in both wet and mesic forests. The most affected ecosystem is the early successional stage of the dry seasonal submontane rainforest. The main infestation in Hawai’i Volcanoes National Park occurs at 4,100 ft. (1,250 m). Reproduction and Dispersal. Fire tree reproduces solely by seed, which is dispersed when primarily exotic birds, especially the nonnative Japanese Silver-eye, and feral pigs (see Volume 1, Vertebrates, Mammals, Feral pig) eat the fruit. Trees reproduce early in life, produce an abundance of fruit and seeds, and grow rapidly. The average adult plant produces 40,000–400,000 fruits per year. In one year, 21 original adult trees can expand the infestation to more than 150 mature trees. Seeds remain viable in the soil for a long time. Flowers are predominantly wind-pollinated but also by introduced honey bees. Impacts. By creating monospecific stands with a dense canopy that shades out understory herbaceous plants, fire tree interferes with and prevents natural succession. It invades early succession sites on lava flows and ash, where the dominant vegetation is evergreen ohia and koa trees, along with native tree ferns. Ohia is a primary pioneer plant on recently deposited cinders and ash, which are nitrogen poor. The open-canopied vegetation in ohia forests, because of the variable substrate, provides good habitat for the initial growth of fire tree. Birds that perch on ohia disperse fire tree seeds in their droppings. In sites that have both part shade and part sun, seeds germinate easily and grow rapidly. Because those sites are deficient in nitrogen, any species, such as fire tree, that can fix nitrogen has a competitive advantage. Fire tree quadruples the normal amount of nitrogen in the soil, enabling itself and other invaders to grow better and faster. As the fire tree stands develop a dense canopy, all understory plants are shaded out, halting the successional process. The amount of leaf litter also inhibits germination of native plants. Management. No long-term control methods have been discovered. Because seeds are spread by nonnative birds and animals, keeping populations of those species under control will limit fire tree invasions. Although physical means of removal are feasible in crop areas,

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they are generally precluded in natural areas because of the destruction that would occur to the environment. Goats can browse fire tree, but goats pose other problems to Hawai’i’s indigenous plant life. Even though it is expensive and labor intensive, chemical control has received the most attention in research. Undiluted glyphosate is the most effective treatment. Direct injection of the herbicide into the tree trunk protects nontarget plants that may be affected by sprays. The search for biological control organisms began in 1955, but because the most promising insects also attacked mango and avocado trees, the effort was abandoned. Botrytis cinerea, a pathogen native to Hawai’i, causes the fruit to rot, both reducing seed viability and making fruit less attractive to birds that disperse seeds. Adults and larvae of fruit-eating insects carry the infection from tree to tree. Fruit-eating insects, such as Amorbia emigratella and Cryptoblabes gnidiella, can be reared in laboratories, inoculated with the pathogen, and released in fire tree areas. Using native species is preferable to introducing new organisms to the islands. A moth (Caloptilia sp. nr. schinella), from the Azores and Madeira Islands, was released in 1991 in Hawaiian fire tree stands. Although not host-specific, the two-spotted leafhopper (Sophonia rufostachia) has killed fire tree on the island of Hawai’i. A butterfly (Phyllonorycter myricae) is under investigation. A fungal leaf pathogen (Septoria hodgesii sp. nov) that attacks southern wax myrtle in the southeastern United States, may also be a possibility.

Selected References Benton, Nancy. “Fire Tree.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2009. http://www.nps.gov/plants/alien/fact/ mofa1.htm. “Fire Tree, Firetree, Faya Bush (Morella faya).” Stopping the Silent Invasion. Hawaii Invasive Species Partnership, 2008. http://www.hawaiiinvasivespecies.org/pests/firetree.html. IUCN/SSC Invasive Species Specialist Group (ISSG). “Morella faya (Tree, Shrub).” ISSG Global Invasive Species Database, 2006. http://www.invasivespecies.net/database/species/ecology.asp?si=100. Seibold, Ryan. “Controlling Fire Tree (Myrica faya) in Hawaii.” Restoration and Reclamation Review. Student On-Line Journal (Hort 5015/5071). University of Minnesota, Department of Horticultural Science, St. Paul, 2001. http://purl.umn.edu/59731.

n Melaleuca Also known as: Paperbark tree, punk tree, white bottlebrush tree, paperbark tea tree Scientific name: Melaleuca quinquenervia Synonyms: Melaleuca leucadendron, M. viridiflora var. angustifolia, M. viridiflora var. rubiflora, Metrosideros quinquenervia Family: Myrtle or Eucalyptus (Myrtaceae) Native Range. Eastern Australia, New Guinea, and New Caledonia. Melaleuca is native to a narrow zone, 25 mi. (40 km) wide, of seasonally flooded coastal lowlands in northeastern Australia. Trees are commonly used for park plantings in Australia, and because development threatens it in its native habitat, efforts have been made to preserve melaleuca in its native range.

558 n TREES Distribution in the United States. Widespread in southern Florida, concentrated southward of Lake Okeechobee and on both coasts, where it is invasive to several million acres. Also in southern California, southern Texas, Louisiana, and Hawai’i. Description. Melaleuca is a slim, erect evergreen tree growing up to 80 ft. (24 m) tall, occasionally to 108 ft. (33 m), with a slender, non-spreading crown. Branches, growing upward, not outward, are irregularly spaced off the trunk. The white bark is spongy or corky and paperlike, prone to peeling in layers similar to a paper birch tree. The gray-green leaves are alternate and lance-shaped, as much as 4–6 in. (10–15 cm) long, but narrow. Five parallel longitudinal leaf veins are prominent. When mature, the leaves are flat, stiff, and leathery. Because of the oily content, the leaves release a camphorlike odor when crushed. Melaleuca has both a netMelaleuca is a serious invader in the Everglades, where it was originally work of roots near the soil surplanted to create forests. (Native range adapted from USDA GRIN and face and many vertical roots. selected references. Introduced range adapted from USDA PLANTS The vertical roots tap the water Database, Invasive Plant Atlas of the United States, and selected references.) table, allowing the plant to survive dry conditions. Although individual creamy white flowers are small, they occur in showy bottle-brush like spikes at the ends of the branches. The spiky inflorescences are 0.75–2 in. (2–5 cm) long. Each flower has five petals and 30–50 stamens. Because the flower stem is indeterminate, it continues to grow after flowering. The fruit is a small, woody seed capsule that resembles a cylindrical or squarish button. Each flower spike can produce 30–70 seed capsules, and each capsule contains 200–350 tiny seeds. Closed seed capsules are stored on the tree, and one stem or branch may have up to 10 clusters of seed capsules alternating with leaves because the stem continued to grow and reflower several times. Related or Similar Species. The genus Melaleuca has many species in its native Australia, but no others are considered invasive to the United States. The crimson bottlebrush plant, a common ornamental shrub in the same family as melaleuca, has similar flowers, but they are distinctly red.

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A. Melaleuca trees are slender and straight with a compact crown. (Forest and Kim Starr, U.S. Geological Survey, Bugwood.org.) B. Bark peels off in layers. (David Nance, USDA Agricultural Research Service, Bugwood.org.) C. The long narrow leaves are stiff and leathery. (Amy Ferriter, State of Idaho, Bugwood.org.) D. Woody fruit capsules remain on the tree. (Albert [Bud] Mayfield, Florida Department of Agriculture and Consumer Services, Bugwood.org.) E. Bottle-brush spikes of flowers grow at ends of branches. (Amy Ferriter, State of Idaho, Bugwood.org.)

Introduction History. Melaleuca was deliberately introduced to southern Florida as an ornamental in the late 1800s or early 1900s because of its showy flowers. It was also used as a means of reclaiming, or drying out, swampland and was planted for windbreaks and fencerows. In the 1930s, trees were planted for erosion control on canal levees, the south shore of Lake Okeechobee, and in Big Cypress National Preserve. Seeds were deliberately scattered over the Everglades to create forests. The trees remain concentrated around the regions where they were initially introduced. As late as 1970, melaleuca was still considered a good landscape tree. Over a million trees were planted for erosion control in Hawai’i. Habitat. A subtropical tree, melaleuca grows primarily in wet or swampy sites and grows best in wet areas with frequent fires. It invades several natural habitats, such as sawgrass marshes, wet prairies, lake margins, pine flatwoods, and cypress stands. Plants do best in seasonally wet sites, but they can also grow in both standing water and in drained uplands. Melaleuca will also take over disturbed areas such as roadsides, ditch banks, farmland, and urban environments, but disturbance is not necessary for invasion. Wet sites are more likely to be invaded. It is tolerant of brackish water, growing in mangrove swamps in both its native range and where introduced. Frost limits the northward expansion of melaleuca. Mature trees are able to survive freezing temperatures, but young trees are susceptible. Melaleuca grows from sea level to 4,500 ft. (1,400 m) elevation in Hawai’i, on all types of soils. However, it is not as invasive on the islands because its preferred habitat of wetlands is less common. Fewer wildfires also limit its competitive advantage. Reproduction and Dispersal. The reproductive advantage of melaleuca lies in its abundant seed production. Saplings that are three years old, and sometimes only one year old, will flower and set seed. November to January is the normal bloom season in Florida, but both flowering and growing seasons will be longer during especially wet years. Because melaleuca can flower up to five times per year, a mature tree can produce a million seeds each year, with more than 50 million stored on the plant in woody capsules. Seed pods must dry before releasing seeds, primarily after stress or disturbance such as frost, fire, physical

560 n TREES injury such as a cut limb, or herbicide application. However, some seeds are released continually, resulting in a steady but light seed fall. Only 10–20 percent of seeds, most of which remain within the capsules for at least 10 years, are viable. Viability of seeds that are released from the capsules is reduced by one-half after eight months in the ground, while others remain dormant for up to two years. Seeds are dispersed by wind and water. Germination takes place a few days after soil becomes moistened. Seeds are able to germinate in both sun and shade and even while submerged. Trees also reproduce vegetatively, having the ability to resprout from roots or stumps after a fire. Impacts. Melaleuca affects not only ecosystems, but also human health. It outcompetes and displaces native species, eliminates wildlife habitat, and poses a fire hazard. Grass and sedge marshes are the habitats most affected in southern Florida. Melaleuca shades out and replaces native vegetation such as sawgrass. Trees frequently form impenetrable thickets that eliminate all other vegetation, resulting in a monoculture that is little used by native wildlife. The Everglades is a watery grassland environment, but when melaleuca trees replace the grass, the area becomes an alien environment to native plants and animals, thereby limiting diversity in the ecosystem. The trees grow very quickly, 3.3–6.5 ft. (1–2 m) per year, and a stand can form a grove up to 600 ft. (180 m) in diameter in only one year. In only 25 years, the species can increase its cover in one square mile (2.6 km2) from 5 to 95 per cent. In densely occupied areas, as many as 31,000 trees and saplings can grow on one acre (0.4 ha) of land. The trees have more biomass than native grasses, providing more fuel for fires. Ground fires burn hotter and can ignite organic soils. The volatile oils in the leaves cause intense crown fires, which threaten both buildings and native trees, incurring higher firefighting costs. Accumulations of leaf litter often build hammocks, or tree islands, above the sawgrass marsh, perhaps altering hydrology and flow of water. Pollen from melaleuca is believed to be a mild allergen, worsened by the plant’s propensity to flower several times a year, causing respiratory problems for many Florida inhabitants. Along with the Brazilian peppertree (see Trees, Brazilian Peppertree), melaleuca is recognized internationally as the greatest threat to the Everglades ecosystem, which is a World Heritage Site and International Biosphere Reserve. Control of the species is a major obstacle to restoration and preservation efforts. Although melaleuca has economic uses, its shortcomings outweigh its benefits. In 1991, its economic benefits, such as use in commercial honey production, were estimated at $15 million. In contrast, assuming the entire Everglades were to become invaded, the potential loss to ecotourism, because a melaleuca landscape is less attractive and is impenetrable to hikers and boaters, was estimated to be $168.6 million. As of 1994, control of melaleuca cost the state of Florida more than $2.2 million each year. From 1991 to 1998, the Southern Florida Water Management district spent over $13 million on melaleuca control, while other agencies also spent millions. For 2003 alone, estimated total costs of control in southern Florida were more than $3 million. Management. Management and containment of melaleuca stands is expensive and requires a long-term commitment. Removal of even a moderately thick stand of trees, either physically or by injecting individual trees with herbicide, may cost hundreds or thousands of dollars per acre. Aerial spraying with herbicide is less expensive, but also less effective. Total eradication may be impossible, but spread of melaleuca can be checked, and some areas can be restored to their natural state. Treatment of dense stands does little good

MELALEUCA n 561

because any disturbance to the tree triggers either seed release or resprouting, which produces more trees. However, concentration of efforts on treatment of trees in outlying areas may prevent new stands from developing. Physical removal is possible only for isolated trees or small stands. Hand-pulling of seedlings may be temporarily successful, but because of the abundant seed production, new seedlings may develop in the same site if it is close to other trees. Medium-size trees may be bulldozed over and larger trees cut, but the roots, limbs in contact with moist ground, or stumps will resprout. Any attempt to manage the stands by fire is ineffective and actually serves to extend the range of melaleuca. Although young seedlings, as well as native plants, are killed, fire triggers seed release from mature trees and also provides a nutrient-rich surface for germination. Chemical applications will cause stressed plants to release seeds, ultimately making the situation worse. Depending on the method of application, various herbicides succeed in killing existing trees. A combination of glyphosate and imazapyr is most effective in both foliar applications and when applied directly to cuts through the basal bark to the cambium layer. Resprouting may occur when glyphosate is used alone. Either glyphosate or imazapyr is effective on cut stumps, a choice when it is unwise to leave dead trees standing. Triclopyr is less effective. Hexazinone applied to the soil at the base of plants is taken up by the roots. Research is currently being conducted to explore biological controls, specifically insects from its Australian native habitat. Five species have been introduced to Florida quarantine for study. Two have been released to the wild and are currently established. Released insects disperse slowly, and reduction in seed production, not eradication of the plant, is the goal. The snout beetle (Oxyops vitiosa) eats growing tips, while the melaleuca psylid (Boreioglycaspis melaleucae) causes foliage and stems to wilt, killing young trees. These two species and the melaleuca defoliating sawfly (Lophyrotoma zonalis) are host-specific, meaning that they only affect melaleuca and do not threaten native plants. The sawfly is being tested for toxicity to wildlife, because some evidence exists that eating the larvae is toxic to animals. The bud-gall fly (Fergusonina sp.), which creates galls on both flower and leaf buds, retarding growth, may also be host-specific but is still undergoing research tests. In contrast, the leaf-blotching bug (Eucerocoris suspectus), although effective at defoliating melaleuca, also attacked other plants and is no longer being considered. Other species are being tested in Australia for potential import.

Selected References Geary, T. F., and S. L. Woodall. “Melaleuca.” n.d. http://www.na.fs.fed.us/spfo/pubs/silvics_manual/ volume_2/melaleuca/quinquenervia.htm. Masterson, J. “Melaleuca quinquenervia.” Smithsonian Marine Station at Fort Pierce, FL, 2007. http:// www.sms.si.edu/IRLspec/Melaleuca_quinquenervia.htm. Mazzotti, Frank J., Ted D. Center, F. Allen Dray, and Dan Thayer. “Ecological Consequences of Invasion by Melaleuca quinquenervia in South Florida Wetlands: Paradise Damaged, not Lost.” Document SSWEC123. University of Florida Institute of Food and Agricultural Sciences (IFAS) Extension, 2008. http://edis.ifas.ufl.edu/uw123. Rayamajhi, M. B., et al. “Australian Paperbark Tree (Melaleuca).” In Biological Control of Invasive Plants in the Eastern United States, by R. Van Driesche et al. USDA Forest Service Publication FHTET-200204, 2002. http://www.invasive.org/biocontrol/8AutralianPaperbarkTree.html. Swearingen, Jil M. “Melaleuca.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2009. http://www.nps.gov/plants/alien/fact/ mequ1.htm.

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n Paper Mulberry Also known as: Wauke (Hawaiian) Scientific name: Broussonetia papyrifera Synonyms: Papyrius papyriferus Family: Mulberry (Moraceae) Native Range. Japan and Taiwan. Distribution in the United States. Southeastern, northeastern, and midwestern states. From Texas east to Florida, north to Massachusetts and New York, and west to Kansas and Oklahoma. Also in California, Hawai’i, and Puerto Rico. Description. Paper mulberry is a deciduous, low-branching tree that may be 33–66 ft. (10–20 m) tall. With many sucker stems emerging from the roots, it might look like a large shrub, with a mounded appearance because the taller stems are in the middle of the clump. Reddish-brown twigs are densely covered with coarse hairs, and the bark is tan or dark gray, either smooth or with shallow grooves or furrows. The soft wood is brittle, and the plant has milky sap. In winter, the tree can be recognized by its conical buds. Leaves are highly variable in size and shape, 2.5–10 in. (6–25 cm) long and 2–3.5 in. (5–9 cm) wide, on 1–3 in. (2.3–8 cm) long petioles. They may be alternate, opposite, or whorled around the stem, and may have 3–5 lobes, none, or be shaped like a mitten. Small leaves are usually not lobed, medium-size leaves are mitten-shaped, and the largest are deeply lobed, with two large lobes and two smaller lobes near the leaf base. They have pointed tips and either a heart-shaped or rounded leaf base. Leaf margins are coarsely toothed. The lower surface of leaves is densely covered with soft matted hairs, while the upper surface is sparsely covered with stiff hairs, making the leaves feel slightly rough to the touch. Leaves turn dull yellow in fall before dropping. Trees have a taproot as well as a system of matted surface roots, which give rise to suckers. Plants are dioecious, meaning that male and female flowers are on separate plants. Greenish flowers develop in April and May, when the leaves emerge. Male flowers are arranged in clusters of drooping catkins, each 1.2–3 in. (3–8 cm) long, which contain many individual small flowers. Female flowers are globular or ball-shaped, 1 in. (2.5 cm) in diameter. The reddish-purple to orange-red, fleshy fruit matures in summer and is an aggregate like a berry, 0.75–1.2 in. (1.5–3 cm) in diameter, looking like a spiky ball. Related or Similar Species. The nonnative white mulberry has both male and female flowers on the same plant. Native red mulberry is distinguished by leaves with a distinct heart-shaped base and only a slight pubescence on the underside. Twigs may be glabrous or finely pubescent, and the fruits are red and elongated. Leaves of the native sassafras, which have a spicy odor or taste, may be unlobed, mitten-shaped, or three-lobed, but the leaf base is distinctly pointed. Yellow-green flowers borne in short clusters are followed by blue-black berries nestled in red cups. White basswood, also native, has unlobed, distinctly heart-shaped leaves on long petioles. Pale-yellow or whitish flowers occur in clusters attached to a long thin bract. Fruit is small, gray, and pea-like. Introduction History. Paper mulberry has been known in Florida since 1903, and most of the plants are male. Because of their rapid growth, trees were planted extensively throughout the southeastern states as ornamentals and for shade around houses. Oceangoing Polynesians who originally settled Hawai’i brought paper mulberry shoots with them.

PAPER MULBERRY n 563

Habitat. Paper mulberry has become a worldwide invasive. It thrives in several climates, preferably where rainfall keeps the soil moist most of the year. Trees can be found in disturbed sites at the edges of forests and fields, and in open ground near urban areas below 5,000 ft. (1,500 m) elevation. They grow best in sun and do not tolerate heavy shade. Especially problematic in riparian zones of floodplain forests, paper mulberry is also known for its tolerance of 3–4 months of seasonal drought. The tree prefers lighttextured soils, such as sands or sandy loams, and can grow in either well-drained or waterlogged sites. Because the foliage is not frost tolerant, the tree often dies back to the ground in winter in cold climates. Reproduction and Dispersal. Paper mulberry reproduces both sexually and vegetatively. Long-distance dispersal is accomplished by birds and wildlife, which eat the fruit and expel the seeds elsewhere. Seeds can germinate one month Paper mulberry trees grow best in climates where soils are moist, after ripening. Although most of especially the southern states and Hawai’i. (Native range adapted from the plants in Florida are male, USDA GRIN and selected references. Introduced range adapted from enough seeds are produced for USDA PLANTS Database, Invasive Plant Atlas of the United States, and paper mulberry to be invasive selected references.) in some areas. Flowers and fruit do not develop in Hawai’i because all plants are male. In all regions, new plants sprout from the roots to create dense thickets. Impacts. Paper mulberry grows aggressively to displace native plant species, which negatively affects wildlife that depend on native plants for forage, cover, and nesting sites. Repeated growth of suckers, which sprout from the surface root system every few feet, makes the plant hard to contain. Because of its shallow root system, trees are frequently blown over in high winds. The roots, however, grow aggressively and can damage pipes and structures. Pollen from flowering plants may cause severe allergic reactions. Management. Although paper mulberry is still available in nurseries, the best management is to avoid planting it. Physical control may be accomplished by pulling small

564 n TREES

A. Trees begin branching close to the base. (Chuck Bargeron, University of Georgia, Bugwood.org.) B. Leaves are variable but often are deeply lobed. (Chuck Bargeron, University of Georgia, Bugwood.org.) C. Small leaves may be mitten-shaped or unlobed. (John Ruter, University of Georgia, Bugwood.org.) D. Twigs are very hairy. (James H. Miller, USDA Forest Service, Bugwood.org.) E. Old trunks are smooth, with shallow grooves. (James H. Miller, USDA Forest Service, Bugwood.org.)

seedlings. Small trees can be cut to the ground repeatedly as plants resprout, or cut in combination with herbicide applications on new growth. Chemical treatments, whether applied directly to basal bark or cut-stump or injected into tree tissue, are all effective. These methods, in contrast to foliar sprays, specifically target paper mulberry and do no damage to nontarget plants. Triclopyr is the most effective herbicide applied directly to cut tissue. Foliar applications of glyphosate, however, can be used to kill small trees if they are thoroughly covered with the herbicide. Herbicide treatments should be done before the fruit and seeds mature. Because of root sprouts, large trees need repeated treatments. The plant appears to be free of pests, and no biological agents are available. Research and data, however, are limited. Several species of fungi and insects are known to attack paper mulberry in its native range. Of the fungi, Aecidium mori var. broussonetia, Dendryphiella broussonetiae, and Phomopssis broussonetiae are host-specific.

Selected References Morgan, Eric C., and William A. Overholt. “Wildland Weeds: Paper Mulberry, Broussonetia papyrifera.” Publication ENY-702, University of Florida Institute of Food and Agricultural Sciences (IFAS) Extension, 2004; reviewed 2010. http://edis.ifas.ufl.edu/in498.

Why Is It Called “Paper” Mulberry?

A

s long as 2,000 years ago, the Chinese used the strong, fibrous inner bark of the tree as a source of fiber for making paper, and it is still used today for high-quality paper in China and Japan. On island environments where fibers such as cotton and silk were unknown, Polynesians and Hawaiians used the bark to make tapa cloth. Traditionally used for clothing and bedding, tapa cloth is valuable because it is warm, water resistant, soft, and washable.

PRINCESS TREE n 565 “Paper Mulberry, Broussonetia papyrifera.” Excerpted from Circular 1529, Invasive Species Management Plans for Florida. Institute of Food and agricultural Sciences (IFAS) Extension, 2008. http:// plants.ifas.ufl.edu/node/74. Swearingen, Jil M. “Paper Mulberry.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2005. http://www.nps.gov/plants/ALIEN/ fact/pdf/brpa1.pdf. Weaver, Richard. “Botany Weed of the Month, Broussonetia papyrifera, Paper Mulberry.” Florida Department of Agriculture and Consumer Services, 2010. http://www.doacs.state.fl.us/pi/enpp/ botany/weed-of-the-month/0410-broussonetia-papyrifera.html. Zheng, Hao, Yun Wu, Jianquing Ding, Denise Binion, Weidong Fu, and Richard Reardon. “Broussonetia papyrifera, Paper Mulberry.” In Invasive Plants of Asian Origin Established in the US and Their Natural Enemies, vol. 1, 2004. http://www.invasive.org/weeds/asian/broussonetia.pdf.

n Princess Tree Also known as: Royal paulownia, empress tree, paulownia, karritree Scientific name: Paulownia tomentosa Synonyms: Bignonia tomentosa, P. imperialis Family: Figwort (Scrophulariaceae) Native Range. East-central China. Distribution in the United States. Eastern and midwestern states, from New York and Massachusetts south to Florida, west to Texas, Missouri, and Illinois. Also in Oregon. Description. Princess tree is a small- to medium-size tree, growing 30–60 ft. (9–18 m) tall and as much as 2 ft. (0.6 m) in diameter. The spread of its canopy can match its height, and branches tend to droop as the tree grows. The stems or twigs are flattened at the juncture of stems and branches. Pith of stems is hollowed or chambered. The olive-brown to darkbrown bark on young growth is thin and smooth, with prominent elongated white lenticels. Twigs are primarily glabrous except for the young tips, areas around the buds, and the upper edges of leaf scars, which are covered with short hairs. Leaf scars are circular. Older bark is gray-brown and rough, but mottled with shiny smooth areas. The large leaves, in opposite pairs on the stem, are broadly oval or heart-shaped, with pointed tips. Margins are usually entire, or sometimes with three shallow lobes, but they may be toothed on small plants. Leaves on young saplings may grow in whorls of three. Leaves on mature trees are 6–16 in. (15–40 cm) long and 4–8 in. (10–30 cm) wide, but leaves on stump sprouts may be twice as large. Leaves are light green, with the lower surface being more pale in color. Both leaf surfaces are fuzzy or hairy, especially the undersides. Princess tree has many shallow, branching horizontal roots, but no strong taproot. The tree flowers in April and May, before the leaves develop, from leaf buds that formed the previous summer. Fragrant, showy flowers grow in conspicuous upright terminal panicles, 6–12 in. (15–30 cm) long, at the ends of the twigs. Bell-shaped pale violet or blue corollas, with five round, unequal lobes, are 2 in. (5 cm) long. The fruit grow in terminal clusters of oval, woody capsules, 1.25–1.75 in. (3–4.5 cm) long, on second-year growth. Initially coated with sticky hairs, the capsules, or seed pods, mature in the fall and become brown, dry, and woody, resembling pecans. Seed pods have four compartments, which together contain as many as 2,000 tiny flat, winged seeds. Capsules remain on the tree throughout winter. Related or Similar Species. Most members of the figwort family in North America are herbaceous. Two other species in the same genus, white-flowered paulownia (P. fortunei)

566 n TREES and elongate paulownia (P. elongata), are recommended for timber plantations in the United States where winter temperatures do not drop below 20ºF (−6.5ºC). Although the native catalpa tree is similar in size, leaves, and flowers, it has distinct differences from princess tree. The pith of catalpa stems is solid and whitish. Its leaves are whorled, with more distinctly pointed tips. Catalpa flowers grow on the current year’s growth, and catalpa fruit are slender pods, 8–18 in. (20– 46 cm) long. Introduction History. After first being taken to Europe in the 1830s by the Dutch East India Company, princess tree was imported to the United States around 1840 as an ornamental landscape tree. The use of seed pods to cushion porcelain cargo shipped from China may be a second possible mode of introduction. Princess tree has been naturalized in the eastern states for more than Grown in plantations for timber, princess tree is widely promoted in 150 years and is also grown on southern states. (Native range adapted from USDA GRIN and selected the West Coast. references. Introduced range adapted from USDA PLANTS Database, Habitat. Princess tree priInvasive Plant Atlas of the United States, and selected references.) marily invades bare or sterile soil in disturbed natural areas, such as burned sites, landslides, and forests defoliated by pests. Roadcuts and construction sites are also potential habitat. Trees thrive on marginal, even toxic, land. They tolerate infertile or acid soils but do best on well-drained soil with a high water-holding capacity and a pH of 6–8. Princess tree can be found along stream banks, on steep rocky slopes, and at the edges of forests where sunlight is sufficient, but not in shady forest interiors. Because it was planted as an ornamental, trees are frequently found around old homesites. Its natural range in China is south of the 0ºF (−18ºC) January isotherm and where annual precipitation is at least 40 in. (1,015 mm). Reproduction and Dispersal. Princess tree reproduces both by seed and from root sprouts. Flowers are insect pollinated in spring. Seed capsules break open to release seed throughout the following winter and into the spring. One large tree can produce 20 million seeds, which are transported long distances by wind and water. Seeds can germinate as soon as they are deposited in a suitable location, which has bare soil, moisture, and direct

PRINCESS TREE n 567

A. White lenticels are prominent on young twigs. (James H. Miller, USDA Forest Service, Bugwood.org.) B. Leaves are lighter green and more pubescent on the lower surface. (James H. Miller, USDA Forest Service, Bugwood.org.) C. Long inflorescences with bell-shaped flowers grow at the ends of twigs. (James R. Allison, Georgia Department of Natural Resources, Bugwood.org.) D. Fruit are woody capsules that resemble pecans. (James H. Miller, USDA Forest Service, Bugwood.org.)

sunlight. Seedlings are intolerant of shade and are susceptible to soil fungi, which causes damping off. Seedlings and small trees grow rapidly and can flower and set seed in 8–10 years. Mature trees, which live for approximately 70 years, become structurally weak. Root sprouts are abundant and can grow more than 15 ft. (4.5 m) in a year. Root cuttings of one-year-old plants are used for propagation in plantations. Impacts. Princess tree grows rapidly and displaces native species by preventing them from recovering after a disturbance. Although it is a poor competitor with established vegetation, princess tree rapidly occupies bare sites where it creates extensive colonies due to its prolific root sprouts. It often competes with rare plants on rocky cliffs and in scoured riparian sites. The litter that accumulates from its large leaves alters soil chemistry by increasing the nitrogen content. Management. Physical control is possible for young plants. They may be hand-pulled, providing that all roots are removed because any fragments may sprout new plants. Large trees may be cut to ground level, which is best done before the onset of flowering in order to prevent seed development. Resprouts from the roots, however, should be treated with herbicides. Girdling can be done where herbicide use is impractical. Cutting through the

Can Paulownia Be Useful?

A

s early as the third century BC, princess tree had medicinal and ornamental uses in China, and has been cultivated in Japan for centuries as a timber tree. The wood is currently valuable in China and Japan for its use in house construction, in furniture, and as a base for veneers. It is prized for being easily carved into gift boxes, toys, musical instruments, bowls, and clogs. In the 1970s, wild trees in the United States were cut for export to Japan. Since the 1990s, trees have been grown in plantations in the Mid-Atlantic and southeastern United States, with Japan being the major market. The tree is currently advertised on the Internet as a wonderful plant that enriches the soil, absorbs soil pollutants from livestock facilities, and is good for strip mine reclamation. Plantations are also touted as a means of saving natural forests from being cut for timber.

568 n TREES

Jimmy Carter and Princess Tree

F

ormer president Jimmy Carter has planted 10–15 acres of paulownia on his farm in Plains, Georgia, and is experimenting with turning them into biofuel. A cabinet that he built from Paulownia elongata wood sold at auction in 2000 for $230,000.

Source: Paulownia Supply, 2010. http://www.paulowniasupply.com/paulownia_history .htm.

bark and into and through the cambium layer completely around the tree about 6 in. (15 cm) above the ground will kill the top parts, but not the roots. Suckers can be controlled with herbicide. Chemical applications of glyphosate or triclopyr are effective on seedlings and small trees. If desirable grasses are present in the infestation, triclopyr is the better choice because it is selective to broadleaf plants. Cut-stump, basal bark, or hack-and-squirt methods are also effective. Herbicides should be applied to stumps immediately after cutting or to basal bark approximately 12–15 in. (30–38 cm) above the ground surface. Hack-and-squirt involves cutting into the trunk several times about 6–18 in. (15–45 cm) above the ground. Glyphosate or triclopyr is then injected into the cuts. All three methods can be done all year if the ground is not frozen. Princess tree is resistant to insects, and no biological controls are known. Of eight species of fungi that occur in its native range in China, four (Ascochyta paulownia, Gloeosporium kawakamii, Mycosphaerella corylea, and Phyllactinia paulownia) may be host-specific. No evidence indicates that any would be a controlling agent.

Selected References Bonner, F. T. “Royal Paulownia.” n.d. http://na.fs.fed.us/pubs/silvics_manual/volume_2/paulownia/ tomentosa.htm. Clatterbuck, Wayne K., and Donald G. Hodges. “Paulownia.” Tree Crops for Marginal Farmland. Revision of University of Tennessee Extension Publication PB 1465 (1992), 2004. http:// na.fs.fed.us/pubs/silvics_manual/volume_2/paulownia/tomentosa.htm. “Princess Tree.” Southeast Exotic Pest Plant Council (SEEPPC) Invasive Plant Manual, n.d. http:// www.se-eppc.org/manual/princess.html. Remaley, Tom. “Princess Tree.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2009. http://www.nps.gov/plants/alien/fact/ pato1.htm

n Russian Olive Also known as: Oleaster Scientific name: Elaeagnus angustifolia Synonyms: Elaeagnus hortensis, E. iliensis Family: Oleaster (Elaeagnaceae) Native Range. Eastern Europe and western Asia, including western Russia, Mongolia, northern China, and Southwest Asia from Kashmir west to Iran and the Caucasus.

RUSSIAN OLIVE n 569

Distribution in the United States. Almost every state except the extreme Southeast, Alaska, and Hawai’i. Especially invasive in the Intermontane West and riparian sites on the Great Plains. Description. Russian olive is a perennial small tree or large shrub as much as 15–35 ft. (4.5–10.5 m) tall. The tallest trees are in cultivation. Trees have a rounded shape, generally with a single trunk and branches loosely arranged. Bark on the trunk is dark brown with deep fissures. Young branches are gray, with a scaly pubescence that is lost as they age. Older branches, covered with smooth reddish-brown bark, remain flexible. Stems, buds, and leaves are densely covered with silvery or rusty scales. Twigs are thorny. Narrow leaves are simple and lanceshaped, 1–4 in. (2.5–10 cm) long and 0.4–1.2 in. (1–3 cm) wide, borne on short petioles in an alternate arrangement. Although leaf margins are not toothed, they may be wavy, Although drought tolerant, Russian olive trees grow primarily in welland leaf tips may be either blunt drained riparian sites throughout the United States. (Native range or pointed. The upper surface adapted from USDA GRIN and selected references. Introduced range of leaves is dull green and adapted from USDA PLANTS Database, Invasive Plant Atlas of the covered with star-shaped sil- United States, and selected references.) very hairs. Lower surfaces are silvery white and densely covered with scales. Leaves do not change color before dropping in autumn. The lateral root system is deep and extensive. Bell-shaped tubular flowers appear in May and June, soon after the plant leafs out, followed by fruit from August through October. Flowers, 0.4 in. (1 cm) long, grow in clusters of 1–10 on short stalks in the leaf axils. Although flowers have no petals, the four yellowishgreenish sepals, which are fused at the base and flared at the top, resemble petals. Flowers are very fragrant, silvery, and scaly outside and creamy yellow inside. The hard fruits are olive-shaped, 0.4–0.8 in. (1–2 cm) long, and remain on the tree all winter or until consumed by birds or other wildlife. They are mealy, greenish-yellow to brown, sometimes tipped with red, and covered with silvery scales. Although each fruit contains only one seed, each tree produces an abundance of fruit.

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A. Russian olive is a shrubby tree. (Norbert Frank, University of West Hungary, Bugwood.org.) B. Narrow lanceshaped leaves have a silvery or gray cast. (Paul Wray, Ohio State Weed Lab Archive, The Ohio State University, Bugwood.org.) C. Twigs have stout thorns. (Patrick Breen, Oregon State University, Bugwood.org.) D. Flowers have four fused sepals. (Joseph Berger, Bugwood.org.) E. Hard fruit each contain one seed. (Patrick Breen, Oregon State University, Bugwood.org.)

Related or Similar Species. Silverberry is the only species in the genus that is native to North America. It is a shorter, root-sprouting shrub with dark young stems that are not silvery. It grows primarily east of the Rocky Mountains but is also found in Idaho and Utah. Russian olive may also be confused with the native silver buffaloberry, which is closely related to Russian olive. Silver buffaloberry grows in the same saline riparian sites, but has opposite leaves and smaller, red-orange oval berries. It grows slowly into short thickets, reaching 10 ft. (3 m) tall after 20 years. The closely related autumn olive (Elaeagnus umbellata) grows in the eastern half of the United States, from the Atlantic coast west to Nebraska, and in Hawai’i, and is considered a noxious weed in some states. Both autumn olive and Russian olive can be found growing together where their ranges overlap. Native to eastern China, Japan, and Korea, autumn olive was introduced to the United States in the 1830s as an ornamental, for windbreaks and wildlife habitat, and to restore degraded land such as strip mines. Although it has the potential of becoming a troublesome weed, seeds are still distributed in some states for wildlife plantings. A deciduous shrub or small tree reaching 20 ft. (6 m), with a habit more bushy than tree-like, it thrives in full sun on disturbed sites. The lance-shaped leaves are alternate and not toothed. The upper surface of the leaves is dark green, with only the underside covered with silver-white scales. Its branches are not flexible and usually have no thorns. It has small, light-yellow flowers in early summer. Many round, juicy, reddish berries dotted with brown to silvery scales mature in autumn, and seeds are dispersed primarily by birds and small mammals. It does not do well in wet sites or in dense forest, although seedlings are shade tolerant. Because it is drought tolerant, it invades grasslands and woodlands, and is typically found in disturbed ground in pastures, fields, and along roadsides. Methods of control are similar to those used for Russian olive. Russian olive also resembles silverthorn, also called thorny olive, which is a nonnative evergreen with brown scaly and hairy twigs. Flowering in late fall, silverthorn matures a few reddish silver-scaly fruit in spring.

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Introduction History. Cultivated in Germany since 1736, Russian olive has been a popular landscaping plant since it was first introduced to North America in the late 1800s or early 1900s. The first records in the West date from 1903 to 1909 in New Mexico, Nevada, and Arizona. By the 1940s, it was a common ornamental in western cities because of its attractive silvery foliage. Young, spiny stems made a good barrier hedge. By 1954, it had escaped cultivation in several western states. As recently as 1984, some government agencies promoted Russian olive for soil stabilization, as windbreaks, and for improvement of wildlife habitat, even subsidizing distribution of seedlings. It is still recommended and sold in nurseries. Habitat. Although Russian olive tolerates seasonal drought, it grows predominantly in wet places, such as riparian sites, where it can withstand both flooding, siltation, and salinity. It often colonizes downstream from dams, where regulated water release changes the natural cycle of seasonal flooding. The tree also requires good drainage, and may not be invasive in Southeastern states. Trees are found in disturbed, seasonally moist floodplain forests and irrigation ditches, but also in drier sites, such as railroad and highway right-ofways, fence lines, and grasslands. It is widely used in mixed-species shelterbelts across the prairie and plains states. Although it tolerates a wide range of soils, from coarse sand to heavy clay, it grows best in deep sandy or loamy soils. As a nitrogen fixer, it has been used extensively for mine reclamation on bare mineral substrate and tailings, but it does not tolerate acidic soils (pH < 6.0). Seedlings are shade tolerant, but adults are not. Russian olive can grow in temperature conditions as low as −50ºF (−45ºC) and as high as 115ºF (46ºC), and from sea level to 8,000 ft. (2,500 m) elevation. Although trees need at least 8 in. (200 mm) of precipitation each year, plants are well adapted to ephemeral water conditions in riparian zones in dry regions. Russian olive is outcompeted by the invasive salt cedar (see Trees, Tamarisk) on salty soils. Reproduction and Dispersal. Reproduction is both sexual and asexual. Trees produce seed when they are 3–5 years old. Birds feed on the fruit and disperse the seeds. Fruit are also eaten by coyotes, deer, and raccoons, and seeds are gathered and stockpiled by small animals. The buoyant seeds may also be transported by water. Seeds are viable for three years but need 60–90 days of cold conditions to germinate. Russian olive also resprouts from buds on the root crown after damage to aerial parts, whether natural or human-induced, and stem cuttings can produce new trees. Impacts. Russian olive interferes with natural plant succession and alters nutrient cycling. It also uses more water than native plants and changes hydrology of streams. By forming dense thickets, plants crowd out and displace native vegetation, particularly riparian forests, resulting in loss of wildlife habitat. Native cottonwoods and willows have narrow germination requirements and cannot grow in the shade. In contrast, germination of Russian olive seeds takes place under a wide range of conditions, and few seedlings die. Plants grow quickly when young, up to 6 ft. (1.8 m) in one year, with the result that Russian olive stands replace the native plant community. Both a pioneer and climax species, Russian olive persists through successional changes. Beavers’ preference for cottonwoods and willows inadvertently favors Russian olive. Russian olive is quick to displace riparian vegetation after disturbances, such as flooding. Trees may also alter the flood regime. Thickets stabilize stream banks and alter hydrology, limiting sites for regeneration of native cottonwoods and changing riparian habitats into dry uplands. In spite of producing abundant fruits, which are eaten by more than 50 species of birds and mammals, monospecific stands of Russian olive lower the quality of wildlife habitat. Birds that require nesting cavities and insect food in native trees are displaced. Waterfowl, such as ducks, avoid water areas bordered by Russian olive.

572 n TREES Because it is a nitrogen fixer, Russian olive changes the chemical composition of infertile soils that native plants may require. Dense thickets also increase the fuel load, resulting in more damaging fires. Management. Because mature stands of Russian olive trees are nearly impossible to totally eradicate, the best management is to destroy small plants as they are discovered. All control methods should be repeated until the seed bank is exhausted. Any physical control on mature plants should be done before seeds mature. Small trees less than 3.5 in. (9 cm) diameter, and their roots, can be pulled out of moist soil. Repeated mowing or burning of seedlings with stems less than 1 in. (2.5 cm) diameter may control the infestation. Tilling is effective to renovate pastures because all saplings and roots are churned up with the soil. However, mowing, cutting, bulldozing, or chaining will remove only the top biomass of larger trees and provide only short-term effectiveness. Roots should be cut below ground level and the rest buried. Stumps may also be burned. Girdling and cutting trunks above ground level is ineffective because of sprouts from the root crown. Any plant debris should be removed from the site because it does not readily decay and poses a fire hazard. Followups should be conducted for several years to remove all sprouts and seedlings. Although chemical control is effective either by foliar spray or basal injection on young trees or resprouts, the best method for mature trees is application of herbicides to cut stumps. A systemic, such as glyphosate or triclopyr, can be used during the growing season, but herbicides such as imazipyr may be more effective when trees are dormant. Trees should be cut as low as possible, to ground level or below, then treated with herbicide. No research has been conducted on biological control of Russian olive. It was promoted as an ornamental because of its resistance to insects or disease. A canker disease (Tubercularia ulmea) that turns leaves brown can occasionally be found on branches and trunks, but it is not a means of control. Phomposis canker (Phomposis arnoldiae, P. elaeagni) may kill seedlings and saplings but is not widespread.

Selected References “Autumn Olive.” Southeast Exotic Pest Plant Council (SEEPPC) Invasive Plant Manual, 2003. http:// www.invasive.org/eastern/eppc/autolive.html. Sather, N., Nancy Eckardt, and TunyaLee Martin. “Element Stewardship Abstract, Elaeagnus umbellata.” Global Invasive Species Team, Nature Conservancy, 1987; revised 2009. http:// wiki.bugwood.org/Elaeagnus_umbellata. Stannard, Mark, Dan Ogle, Larry Holzworth, Joe Scianna, and Emmy Sunleaf. “History, Biology, Ecology, Suppression, and Revegetation of Russian-Olive Sites (Elaeagnus angustifolia, L.).” Plant Materials Technical Note No. MT-43. U.S. Department of Agriculture, Natural Resources Conservation Service, Montana, 2002. ftp://ftp-fc.sc.egov.usda.gov/MT/www/technical/plants/tech notes/PMC_Tech_Note_43.pdf. Tu, Mandy. “Element Stewardship Abstract, Elaeagnus angustifolia.” Global Invasive Species Team, Nature Conservancy, 2003; updated 2009. http://wiki.bugwood.org/Elaeagnus_angustifolia.

n Silk Tree Also known as: Mimosa, silky acacia, powderpuff tree, Scientific name: Albizia julibrissin Synonyms: Albizzia julibrissin, Mimosa julibrissin, Mimosa arborea Family: Pea (Fabaceae) Native Range. From northern Iran and Afghanistan through the Himalayas in northern India and Nebal, and into China and Japan.

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Distribution in the United States. Much of the United States, from California to Florida, north to New York and Massachusetts and west to Illinois and Kansas. Absent from the northern regions of the Midwest, the Great Plains, Rocky Mountains, and Pacific Northwest. Description. Silk tree is a small to medium sized deciduous tree, 10–50 ft. (3–15 m) tall, with a canopy spread of 25–30 ft. (7.5–9 m). It may have one trunk or multiple trunks. The leaf canopy, which gives the tree an umbrella shape, is generally open, allowing sunlight to penetrate. The smooth, thin bark is light brown to gray and covered with lenticels that look like corky dots and dashes. Young stems are lime green, becoming brown and covered with lenticels as they age. Wood is weak and brittle. The doubly compound leaves, alternate on the stem and 6–20 in. (15–50 cm) long, are finely divided and almost fern-like or feathery. The compound leaf Silk tree grows in a variety of environments but is restricted to the may have 8–24 pairs of pinnae, southern half of the United States by cold winter temperatures. (Native or branches, with 20–60 dark range adapted from USDA GRIN and selected references. Introduced green leaflets, each 0.5 in. range adapted from USDA PLANTS Database, Invasive Plant Atlas of the (1.3 cm) long, on each pinna. United States, and selected references.) The midrib is off center, closer to one margin of the leaflet. The light-pink to dark-pink flowers, showy and sweetly fragrant, emerge from May through August. Many conspicuous stamen filaments make them resemble small pink pompoms or tufts, 1.5–2 in. (3.8–5 cm) long, with white bases. Flowers are sessile and occur in loosely branched clusters of 15–25 at the ends of the current year’s growth of branches. Flat, linear, straw-colored seed pods, 6 in. (15 cm) long, contain 5–10 light brown oval seeds, each 0.5 in. (3.8 cm) long. Seed pods hang in large clusters and turn from light green to dark brown as they mature in August and September. In winter, the pods are whitish tan. Although they split to release the seeds, the empty pods remain on the trees all winter. Related or Similar Species. Woman’s tongue, an introduced tree species native to southern Asia and northern Australia that is sometimes invasive, is found in California,

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A. Foliage is open and lacy looking. (Rebekah D. Wallace, Bugwood.org.) B. Long leaves are pinnately compound. (James H. Miller, USDA Forest Service, Bugwood.org.) C. Flowers resemble fluffy pompoms. (Rebekah D. Wallace, Bugwood.org.) D. The smooth bark is spotted with lenticels. (James H. Miller, USDA Forest Service, Bugwood.org.) E. Pods each contain 5–10 seeds. (James H. Miller, USDA Forest Service, Bugwood.org.)

Texas, Florida, Hawai’i, Puerto Rico, and the Virgin Islands. It is distinguished from silk tree by its creamy or white flowers with numerous long stamens and a longer seed pod, up to 1 ft. (30 in). The seed pods, which do not split when ripe, remain on the tree in winter. The dried seeds make a rattling sound when the pods are disturbed by wind. Leaflets are more rounded, and leaves do not appear as feathery. The crimson bottle brush shrub, a member of the myrtle family and native to Australia, has similar pompom or bottle brush flowers. It can be distinguished by the red flower color, lance-shaped entire leaves, and woody capsules or seed pods. Silk tree, especially seedlings or saplings, may be confused with native pinnately compound legumes. Native to the southeastern United States, littleleaf sensitive-briar is an arching perennial vine with prickly stems and lavender to pink flowers. Partridge pea, also native to the Southeast, is a non-woody annual forb with five-part yellow flowers. Honeylocust, native to the Mississippi River drainage system, can be a very large tree, up to 100 ft. (30 m) tall. Its pinnate leaves have longer leaflets, 1 in. (2.5 cm), and branches often have 1.2–4 in. (3–10 cm) long thorns. Greenish or whitish flowers are tiny, and the long seed pods, 6–8 in. (15–20 cm), are slightly curved or twisted. Introduction History. Silk tree was introduced to the United States in 1745 as an ornamental because of its finely divided foliage and its showy, fragrant flowers, which are attractive to hummingbirds. It also requires little maintenance. Trees have been used to reclaim disturbed areas in shoreline or riparian sites, and the species is readily available at nurseries or on the Internet. Habitat. Silk tree is an invader of disturbed habitats, and can be found along roadsides and in open vacant lots in urban or suburban areas. It can grow in a variety of soils, including clay, loam, and sand, either alkaline or acidic. It is tolerant of drought, wind, salty soils, and moderate salt spray. Soils can be dry or wet, and plants can be a serious problem in riparian zones along scoured shorelines. Although the plant prefers full sun, it can grow in part shade. It is rare under full forest canopy. Limited by cold winters, silk tree grows below 3,000 ft. (900 m) elevation. Reproduction and Dispersal. Silk tree produces a very large seed crop and also spreads vegetatively. Most seeds fall around the parent plant, but they may be carried long distances by animals or by water. Seeds may also be a contaminant in fill dirt. The impermeable seed coat requires scarification to germinate, enabling seeds to be viable for many years. One

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study showed that 90 percent of seeds germinated after 5 years, and 33 percent germinated after 50 years. Damage to the top portion of the tree will trigger regrowth from the roots. Sprouts can grow over 3 ft. (1 m) in one season, and multiple root sprouts can result in dense colonies of trees. Impacts. Silk tree’s wide tolerance to environmental conditions enables it to outcompete a wide variety of native trees and shrubs in disturbed areas. The tree is also a strong competitor in open areas and at forest edges. It has a distinct advantage because it grows on several soil types and reproduces profusely from large seed crops and also has the ability to resprout after damage. Dense stands or thickets reduce sunlight and nutrients for native plants. As a nitrogen fixer, it alters soil chemistry. On riparian sites, scoured banks provide open habitat for germination of seeds, and water currents provide a means of seed dispersal. Management. Ideal control is to limit planting and to remove existing plants from the landscape. Because physical control alone is usually inadequate, herbicide application is appropriate. Young seedlings can be pulled by hand, but care must be taken to remove all the roots to prevent resprouting. Root sprouts can be repeatedly cut as they emerge or treated with herbicides. Midsize trees may be cut at ground level, preferably before flowers mature to prevent seed set. Herbicide should be applied to the resprouts. Girdling may be necessary for large trees that cannot be cut down or sprayed with herbicides. Cutting through the bark all around the base of the trunk, about 6 in. (15 cm) off the ground, will kill the upper part of the tree but not the roots. Resprouts should be treated with a herbicide. Chemical applications include foliar spray, cut-stump, and injection with either glyphosate or triclopyr. Resprouts, small areas, or thickets are appropriate for foliar spraying where no damage will be done to nontarget native plants. Because it targets broadleaf plants, triclopyr is a better choice if grasses are present. Cut-stump applications should be used where sprays might damage desirable natives. Herbicide application should be done within one minute of cutting the tree. Very large trees can be injected with imazapyr or triclopyr. Mimosa wilt (Fusarium oxysporum f. perniciosum), a fungus transferred through the soil, is a potential biological control. It infects the root system of the tree and can be fatal. Although currently not used, research is needed to ascertain its effectiveness.

Selected References “Albizia lebbeck.” In Identification and Biology of Non-Native Plants in Florida’s Natural Areas, edited by K. A. Langeland and K. Craddock Burks. University of Florida, IFAS, 1998. http://www.fleppc .org/ID_book/albizia%20lebbeck.pdf. Miller, James H. “Silktree, Mimosa.” In Nonnative Invasive Plants of Southern Forests: A Field Guide for Identification and Control. General Technical Report SRS-62. U.S. Department of Agriculture, Forest Service, Southern Research Station. Asheville, NC, 2003. http://www.invasive.org/eastern/ srs/S_M.html. “Mimosa.” Southeast Exotic Pest Plant Council (SE-EPPC) Invasive Plant Manual, n.d. http://www .se-eppc.org/manual/mimosa.html. “Mimosa Tree, Albizia julibrissin.” Excerpted from University of Florida, IFAS Extension, Circular 1529, Invasive Species Management Plans for Florida. University of Florida Institute of Food and Agricultural Sciences (IFAS) Extension, 2008. http://plants.ifas.ufl.edu/node/29. Remaley, Tom. “Silk Tree.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2005. http://www.nps.gov/plants/alien/fact/ alju1.htm.

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n Strawberry Guava Also known as: Cattley guava, purple guava, pineapple guava, purple strawberry guava, cherry guava, waiawi (Hawai’i) Scientific name: Psidium cattleianum Synonyms: Psidium littorale var. longipes Family: Myrtle (Myrtaceae) Native Range. Atlantic coast of southeastern Brazil. The red-fruited strawberry guava originates from 3,000 to 4,000 ft. (900–1,200 m) elevation in eastern Brazil, while the yellow-fruited varieties are native to coastal Brazil. Distribution in the United States. All major islands of Hawai’i, subtropical Florida, and Puerto Rico. Also in Arizona. Description. Strawberry guava is an evergreen shrub or small tree usually growing 6–20 ft. (1.8–6 m) tall, but it can reach 25 ft. (8 m). The trunk is smooth and pale brown, and multiple sprouts from the roots may cause the plant to be shrubby. Young branches are round and pubescent. The elliptical to oblong leaves, arranged opposite on the stems, vary in size, 2–5 in. (5–13 cm) long and 1–2.5 in. (2.5–6.5 cm) wide. They are glossy dark green, leathery, and aromatic, with smooth margins. Lateral veins are not prominent. Flowering and fruiting occur all year. Flowers, 1.2 in. (2.5 cm) wide, grow singly in leaf axils. The white petals surround a mass of white and yellow stamens. Fruit is a round, red berry, 1.2–2.4 in. (3–6 cm) in diameter. The whitish flesh is translucent and very juicy. It is sweet when ripe, tasting somewhat like strawberries. Two varieties have yellow fruit. Psidium cattleianum f. lucidum is a narrow tree, while Psidium catStrawberry guava is considered to be one of the worst invasive pests in Hawai’i. (Native range adapted from USDA GRIN and selected tleianum var. littorale is more references. Introduced range adapted from USDA PLANTS Database, substantial. Each fruit contains many small, hard, tan seeds. Invasive Plant Atlas of the United States, and selected references.)

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A. The trunk of a strawberry guava tree is smooth. B. The leathery leaves are opposite on the stem. C. The showy flowers have many stamens. D. The sweet fruits are round berries. (Forest and Kim Starr.)

Related or Similar Species. The common guava (Psidium guajava) is variable in form because many cultivated varieties exist. Its leaves are larger, 1.6–6 in. (4–15 cm) long, and stiff. Leaf cuticles are waxy, and the undersides of leaves are pubescent, with prominently raised veins. Its bark is smooth, reddish brown, and mottled with reddish brown, gray, or white patches. The white flowers turn yellow as they mature. Fruit is yellow or pink berries, 1.2–2.4 in. (3–6 cm) in diameter, with many yellow or white seeds. Introduction History. Strawberry guava was introduced into Florida in the 1880s as both an ornamental plant and as a fruit crop, and has been planted extensively. Fruit is used in fruit drinks and in jam. By the 1950s, the plant was considered to be naturalized and growing wild. It was introduced to Hawai’i in 1825, probably for similar purposes. It is currently used for firewood in Hawai’i. Habitat. Strawberry guava grows in a variety of habitats in tropical and subtropical climates, from dry to moist forests. Its broad tolerance to environmental conditions may be explained by its genetic variability. Although it is most abundant below 2,600 ft. (800 m), it grows at elevations as low as 330 ft. (100 m) and as high as 4,265 ft. (1,300 m). In Hawai’i, the tree grows from sea level to 4,000 ft. (1,200 m) elevation. Yellow-fruit forms are more common at lower elevations, while red is more common at higher elevations. Trees grow in a range of annual rainfall from 50 in. (1,250 mm) to 275 in. (7,000 mm). Although the species grows readily in disturbed sites, such as roadsides and pastures, it can invade undisturbed healthy forests. It has been found in 23 different vegetation types in Hawai’i, but is most common in moist forests, both lowland and submontane, especially sites where feral pigs (see Volume 1, Vertebrates, Mammals, Feral pig) are present. It is quick to invade wet ohia tree and tree fern rainforest as well as wet ohia tree and koa tree rainforests. Extremely shade tolerant, seedlings and root sprouts can grow in dense shade under taller plants, including adult strawberry guava trees. It easily survives on acidic soils and heavy tree fern litter, both of which are common in natural Hawaiian rainforest. Where native seedlings may be killed by deep leaf litter, small strawberry guava stems bend under the weight. They not only survive but send up vigorous shoots. Mature trees are hardy to about 22ºF (−5.5ºC). Yellow-fruited varieties are somewhat less tolerant of freezing temperatures. Reproduction and Dispersal. Strawberry guava reproduces and spreads both sexually and vegetatively. The number of seeds contained in each fruit can be 25–70. Although seeds have a short period of viability, they have a high rate of germination. No extensive seed bank

578 n TREES remains in the soil. The numerous fruits are consumed by birds and feral pigs, and the seeds are excreted elsewhere. Two nonnative birds, the Common Myna (see Volume 1, Vertebrates, Birds, Common Myna) and the Japanese White-eye (see Volume 1, Vertebrates, Birds, Japanese White-eye), are suspected of transporting seeds, but no evidence exists. Feral pigs play a major role in seed dispersal of strawberry guava. Although scarification is not required, seeds germinate more quickly after passing through the pig’s digestive tract. Calculations, extrapolated from a count of the number of seeds found in pig scat, indicate that in a densely infected area of Kipuhulu Valley on Mau’i, each pig was responsible for dispersing about eight million seeds each month during the peak fruiting season. Dense thickets develop when roots sprout stems. Stems from root suckers grow rapidly and have a good survival rate. Root sprouts also have more leaf area and are more vigorous because of nutrients stored in the roots. Cuttings will root. Impacts. Considered by some to be the worst plant pest in Hawai’i, strawberry guava may affect one-half of the land area of the islands. The tree alters habitat in parks and preserves and is a major threat to the native flora and fauna. It is present on approximatley 300,000 ac. (120,000 ha) of natural preserves on the island of Hawai’i alone. It has a competitive advantage for several reasons. It produces abundant fruit and seeds, and it grows rapidly. It tolerates shade and leaf litter, sends up sprouts from roots, and may exude alleleopathic compounds. Strawberry guava has become the dominant tree in several of Hawai’i’s native forests, including within the boundaries of two national parks. Monospecific thickets of strawberry guava trees are very dense, shading out native plants in both forests and in formerly open woodlands. Stem densities in thickets have been measured as high as one every square foot (9 per m2). A dense network of feeder roots forms a mat at the soil surface, allowing little else to grow. The tree also threatens groundwater supplies and stream flow. Strawberry guava uses about 25 percent more water in transpiration than natural rainforest trees require. Strawberry guava, as well as common guava and Surinam cherry, is a major host for the nonnative Caribbean fruit fly, which also spreads to commercial crops. Decreased yield and damaged fruit costs approximately $7.8 million a year for papaya growers alone. Management. Because they are a major dispersal factor, feral pigs must be controlled before strawberry guava infestations can be eliminated. Re-infestation is low in intact, pigfree forests, even when sources are nearby, and recovery potential is good. However, the absence of pigs will not ensure the absence of strawberry guava. Elimination of pigs must be followed by physical control, chemical control, or both. Physical control is only possible on seedlings and saplings that have grown from seed. After being pulled out, they must be removed from the site, because plants left on the ground can resprout or grow roots in high-precipitation areas. Because of the extensive root system, pulling out plants is less effective on root sprouts. Strawberry guava is sensitive to several types of chemical application. Triclopyr, dicamba, picloram, and 2,4-D are effective when applied to cut surfaces. Basal bark application of 2,4-D, picloram, and triclopyr also work well. Although glyphosate sprayed on foliage proved to be ineffective in the long term, it works well when applied directly to slashed trunks. Long-term management may depend on biological agents, but they must not become a threat to commercially grown common guava. Of seven potential biological control species found to attack strawberry guava in its native Brazil, a leaf-galling scale insect (Tectococcus ovatus) appears to be a good candidate. The formation of galls on new leaves where the insect feeds saps energy from the plant that would normally be used for growth and the production of fruit. The insect does not kill the tree but reduces its vigor and limits its ability to spread. After extensive testing on more than 80 plant species, it was determined that the leaf-galling

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Resistance to Biological Control

P

ublic outcry delayed the proposed release of an insect to control strawberry guava. Some Hawaiians had several concerns. They were afraid that the insect would attack commercial guava plantations. They also wanted to continue gathering wild strawberry guava fruit and grow the trees on their own property. They were also worried that they would have no wood for smoking meat, or that forests of dead strawberry guava trees would promote forest fires.

insect is host-specific. Neither the common guava nor the closely related ohia tree is susceptible. Fewer fruit will also reduce the number of fruit flies that infest commercial crops. Because the insect is flightless, it relies on crawling or wind for dispersal, and unless facilitated, its spread will be slow. Permits were granted in April 2008, but the release scheduled for 2009 was delayed.

Selected References Benton, Nancy. “Strawberry Guava.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2009. http://www.nps.gov/plants/alien/fact/ psca1.htm. Langeland, K. A., and K. Craddock Burks, eds. “Psidium cattleianum.” In Identification and Biology of Non-Native Plants in Florida’s Natural Areas. Florida Exotic Pest Plant Council (FLEPPC), 2008. http://www.fleppc.org/ID_book/psidium%20cattleianum.pdf. Motooka, P., et al. “Psidium cattleianum.” In: Weeds of Hawai’i’s Pastures and Natural Areas: An Identification and Management Guide. College of Tropical Agriculture and Human Resources, University of Hawai’i at Manoa. 2003. http://www.ctahr.hawaii.edu/invweed/WeedsHI/ W_Psidium_cattleianum.pdf Tunison, Tim. “Element Stewardship Abstract, Psidium cattleianum.” Global Invasives Team, Nature Conservancy, 1991; updated 2009. http://wiki.bugwood.org/Psidium_cattleianum. “Waiawi Biocontrol Controversy.” Environment Hawaii 19(1): 2008. http://www.hear.org/articles/envi ronmenthawaii/eh200807vol19no01/strawberryguavacontroversy200807.pdf.

n Tamarisk Also known as: Saltcedar, salt cedar, and others; see below. Five-stamen tamarisk, Chinese tamarisk (Tamarix chinensis); pink-flowered tamarisk (T. ramosissima); small-flowered tamarisk (T. parviflora); French tamarisk (T. gallica) Synonyms: Tamarix juniperina, T. petranda, T. pallasii var. brachystachys Family: Tamarisk family (Tamaricaceae) Native Range. Arid or semiarid regions of southern Europe and Asia, from the Mediterranean region east to Korea. Five-stamen tamarisk is native to east-central China. Pink-flowered tamarisk is from south-central Asia, from the Ukraine east through southern Russia, Kazakhstan, Mongolia, and western China. This species extends into Southwest Asia, including Iraq, Iran, Afghanistan, and western Pakistan. Small-flowered tamarisk is native to the Balkan peninsula and Turkey, while French tamarisk originates in the Mediterranean Europe regions of Italy, France, and Spain.

580 n TREES Distribution in the United States. Tamarisk species are found primarily in the hot and arid western, southwestern, Great Basin, and Great Plains states. While present in some of the eastern states, the trees are less invasive in those more humid climates. With few exceptions, five-stamen tamarisk is limited to the Great Plains and western states. Pinkflowered tamarisk has a similar distribution but is absent from the Pacific Northwest and present in the Southeast. Smallflowered tamarisk is generally found throughout contiguous United States, with some absences in the northern and Great Plains regions. French tamarisk grows primarily in the mountain and southwestern states, but also occurs in the Southeast. Description. Four tamarisk species are considered to be invasive, none of which is easily distinguishable from vegetative characteristics. Although the worst two, five-stamen tamaTamarisk species are distinct in their native ranges, but hybridize in the risk, also called Chinese tamaUnited States. (Native range adapted from USDA GRIN and selected risk, and pink-flowered, also references. Introduced range adapted from USDA PLANTS Database, called saltcedar, are distinct Invasive Plant Atlas of the United States, and selected references.) species in their native ranges, hybridization in the United States confuses identification. All four species, including small-flowered tamarisk and French tamarisk, are commonly referred to as saltcedar or simply tamarisk. Tamarisk plants are deciduous shrubs or bushy trees growing 30 ft. (9 m) or more tall. Normal growth is a tree with one trunk, but with disturbance, the plant may form multiple sprouts from the base. Although stands may be dense, individuals are loosely branched, giving the plants an airy look. Bark on young growth is smooth reddish brown, changing to furrowed dark brown or dark purple on older and larger plants. Tiny leaves, 0.06 in. (1.5 mm) long, are alternate on the stem but are closely packed and scaly, resembling those of cedars. That characteristic combined with its tendency to grow in salty environments is the basis for the common name saltcedar. Leaves have salt-secreting glands and are often encrusted with salt. The drought-tolerant leaves, which are deciduous, have water-storing tissue and sunken stomata.

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Salt cedar has an extensive root system, consisting of both a deep taproot and lateral roots, the relative importance of each type is dependent on soil characteristics and depth to water table. Lateral roots are 12–16 in. (30– 40 cm) below the soil surface. The taproot gives the plant important access to deep underground water sources, enabling it to survive in very dry habitats. Flowering generally coincides with snowmelt and summer rains, usually from April through September, but can occur continuously if water is available. White, light-pink, or reddish flowers are small, less than 0.2 in. (5 mm) long. Grouped in short, dense panicles, 2 in. long (5 cm), of individual racemes at the ends of the current year’s growth, they appear feathery. Fruit is a capsule containing many tiny seeds, less than 1 mm long, which may be produced all summer. Related Species. A noninvasive species also native to Southwest Asia, athel tamarisk, is an evergreen species growing Five-stamen tamarisk and pink-flowered tamarisk, primarily found in the in hot deserts. Although leaves drier western states, are the two most invasive species, (Native range are not scaly, they conspicu- adapted from USDA GRIN and selected references. Introduced range ously sheath the stem. Branch- adapted from USDA PLANTS Database, Invasive Plant Atlas of the United States, and selected references.) lets have a drooping habit. Introduction History. The earliest record, 1823, is in New York City, and the trees were available at East Coast nurseries by the 1930s. The plant was brought to the western states sometime in the 1850s. In the early 1900s, the trees were recommended as ornamentals and for windbreaks, shade for small livestock, and fuel. As late as 1964, it was still recommended for windbreaks on the Great Plains. It was intentionally planted along rivers in western states to control bank erosion. Regulation of water flow in reservoirs and diversion channels allowed the tree to rapidly spread along drainage ways. Habitat. The tolerance of tamarisk to many habitats may indicate that plants are actually several species, ecotypes, or hybrids. They most commonly grow along river systems, springs, lake shores, reservoirs, floodplains, and irrigation ditches where they have access to water. The trees are absent, however, from areas susceptible to long-term inundation

582 n TREES because they cannot survive more than three months of standing water. As a phreatophyte, tamarisk grows its roots down to the water table but is not dependent on groundwater. It grows on many substrates but is most commonly found on finetextured soils. Most soils are alkaline. The plant tolerates extreme salt concentrations, greater than 50,000 ppm of soluble salts, but is usually found on soils with 700–15,000 ppm. Tamarisk can form dense thickets where depth to groundwater is less than 20 ft. (6 m), but plants will be more widely spaced where the water table is further below the surface. It grows best in full sun and is shaded out by tall cottonwoods or willows. Bare sites suitable for germination of seedlings are created when dams and reservoirs alter stream flow. Floodplains and reservoirs subject to receding water expose bare land to colonization. Flood control also changes the dynamics of river flow, preventing or changing Except for a few northern states, smallflower tamarisk has a wide the season of large flows. Tamadistribution. French tamarisk is concentrated in the western desert and risk is less common along rivers mountain states and in the southeast. (Native range adapted from USDA that consistently flood in spring GRIN and selected references. Introduced range adapted from USDA because the high water scours PLANTS Database, Invasive Plant Atlas of the United States, and selected the banks free of seeds and references.) small plants. When land supporting native riparian vegetation is converted to agriculture, bare sites become available for tamarisk seed germination. Plants are found from below sea level to 6,600 ft. (2,000 m) elevation in Death Valley, California. The tree survives both cold winters and summer temperatures as high as 107ºF (42ºC). In extremely cold climates, plants die back to the ground in winter. Reproduction and Dispersal. Reproduction is both sexual and asexual. Tamarisk easily spreads by means of both seed production and root sprouts. One-year-old plants can flower and set seed. Tamarisk produces thousands of tiny seeds from each flower, and one mature plant can produce more than 500,000 seeds in one season. The seeds weigh very little and have short hairs, which facilitates wind dispersal. Both wind and water can carry the seeds long distances. They are also easily spread to other water systems via boats, fishermen,

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A. Trees become shrubby when branches sprout from the base. (Steve Dewey, Utah State University, Bugwood.org.) B. Leaves of athel tamarisk (left) smoothly sheath the twig, compared with the scaly leaves of other species (right). (Joseph M. DiTomaso, University of California-Davis, Bugwood.org.) C. Panicles of small flowers grow on the ends of twigs. (Steve Dewey, Utah State University, Bugwood.org.)

trailers, and water ballast. Seeds are viable for about five weeks and can germinate 24 hours after moistening. They have no dormancy requirements. Seeds produced later in the season have a better germination rate. In order to survive their first year, seedlings need saturated soil for the first few weeks, a high water table, and open, sunny conditions with no competition. Seedlings establish easiest on sandy soil where water recedes, such as reservoir margins or stream banks, opening bare areas to colonization. Although tamarisk seedlings will die if the soil dries within the first four weeks, they are more drought tolerant than willow seedlings. The slow rate of growth of tamarisk seedlings, less than 5 in. (12.5 cm) tall after eight weeks, is offset by a high rate of establishment. Few seeds survive cooler winter temperatures, meaning that no large seed bank exists in the soil. Tamarisk vigorously reproduces by vegetative means. Both mature plants and roots grow rapidly. Shoots can grow 10–13 ft. (3–4 m) in one season. In one year, lateral roots can extend as much as 30 ft. (9 m), and the tap root can grow 16 ft. (5 m). Branches touching moist soil will root. Burned or cut plants will produce numerous sprouts from the root crown and roots. Buried stems or broken pieces readily root. Floods frequently damage plants and distribute the pieces, and fragments may also be carried on boats or trailers. Impacts. Because of its vigorous growth, which literally crowds out the natives, tamarisk displaces native riparian species, such as willow, cottonwood, and mesquite. The plant not only tolerates salty soils, but also increases the salinity. Salt taken up by roots deep in the soil is exuded onto the leaves of the plant. As leaf litter accumulates, the surface soil becomes too salty for native species. The plant is less invasive where rivers are not controlled, and displacement of native species is greater where hydrological processes have been altered. Perhaps because of its greater leaf area, tamarisk uses more water than natives, lowering the water table and causing surface water to diminish or disappear. A mature tree is capable of using 300 gal. (1,135 l) per day. Dense stands may also increase local sediment deposition, and it is also speculated that tamarisk thickets may clog water channels and alter stream flow. The value of tamarisk for wildlife varies according to many factors, including region or watershed, density of the stand, and species. In some areas, such as the Lower Colorado

584 n TREES River in California, biodiversity of birds and small mammals, as well as total populations, are generally lower in tamarisk thickets than where native plant species exist. However, the trees do provide nesting sites in areas that previously had no forest. While ground feeders and seed-eating populations may benefit, fruit-eating birds, cavity nesters, and timber gleaners generally require native vegetation. Although beaver eat young tamarisk shoots, they prefer willows and cottonwoods, giving the tamarisk a competitive advantage. The relationship with other rodents varies with species and location. The scaly leaves, however, are not palatable to most grazing animals, either domestic or wild. Management. Because tamarisk is so widespread and disperses so readily, total eradication may not be possible except in small areas. Furthermore, the site may be permanently damaged due to salt buildup or changes in hydrology. All methods are time-consuming, labor intensive, and expensive. In 1998, complete restoration along a portion of the Rio Grande in New Mexico ranged from $1,850 to $3,200 per acre ($750 to $1,300 per ha). Because roots and pieces vigorously resprout, physical means such as cutting or bulldozing are ineffective if not used in conjunction with other methods. Removal of the aerial parts of the plants, however, can reduce water consumption by as much as 50 percent. If bulldozing is used, plants should be plowed up below the root crown. Small sprouts may be pulled by hand. Burning works best when 25 percent of the biomass is first cut and allowed to dry, and is most successful in the hottest part of summer, when plants are most water stressed. It may take three to four years or more to fully eradicate a tamarisk stand. Because tamarisk fragments resprout vigorously, burning should be followed by spraying new sprouts with a herbicide. Burning cannot be used where tamarisk is mixed with native cottonwoods and willows because those species do not resprout and will be killed. Grazing is a poor option because livestock prefer to graze the native cottonwood and willow seedlings rather than the tamarisk. Chemical control can be attempted in several ways, but care must be taken around waterways where tamarisk grows. Imazapyr, either alone or in conjunction with glyphosate, is the most effective herbicide, affording 70–90 percent control. While glyphosate, 2,4-D,

Successful Eradication

C

oachella Valley Preserve in southern California, home to 180 species of wildlife, contains the only undisturbed watershed remaining in that valley. Originally planted as a windbreak, tamarisk got out of control. Almost three-quarters of the 25 ac. (10 ha) wetland in Thousand Palms Canyon was 80 percent covered by tamarisk, and the spring had dried up. Although it took several years, 1986–1992, and 5,000 person-hours, tamarisk was successfully eradicated from the site. Using primarily hand labor provided by volunteers and California Conservation Corps crews, tamarisk trunks were cut close to the ground and immediately sprayed with a herbicide. The debris was moved to other areas in the preserve where the wood piles provided habitat for birds until the native riparian species regenerated. The spring began flowing soon after the first tamarisk cutting. Seeds of native plants were hand scattered in the area, and the canyon has been successfully restored. Occasional tamarisk seedlings from wind-blown seeds are easily pulled out, preventing re-infestation. Source: Martin, 2001.

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dicamba, or triclopyr will defoliate plants and reduce evapotranspiration and water use, they do not kill the plants. Leaves will grow back. Aerial spraying of herbicides is useful in monotypic stands of tamarisk but cannot be used in areas that include native vegetation. Herbicides can also be applied to freshly cut stumps or around the base of the tree on the bark. Basal application, however, requires more herbicide and is less effective than the cutstump method. Systemic herbicide application is most effective in fall or winter, when the plants are becoming dormant and moving resources to their roots. Biological control may be accomplished by two imported insects. The saltcedar leaf beetle (Diorhabda elongata) from China, west-central Asia, and the Mediterranean, was released in several western states. Seven different ecotypes are being studied. Both adults and larvae eat the leaves and defoliate the plant, and more than one generation develops during a season, two generations in cooler climates and three to four in warmer climates. More than 1,000 beetles on one plant can completely defoliate it. A mealybug (Trabutina mannipara), native to Israel, eats tamarisk twigs.

Selected References Carpenter, Alan T. “Element Stewardship Abstract, Tamarix ramosissima Ledebour, Tamarix pentrandra Pallas, Tamarix chinensis Loureiro, Tamarix parviflora De Candolle.” Global Invasive Species Team, Nature Conservancy, 1998. http://www.invasive.org/weedcd/pdfs/tncweeds/tamaram.pdf. Jacobs, Jim, and Sharlene Sing. “Ecology and management of Saltcedar (Tamarix ramosissima, T. chinensis and T. ramosissima x T. chinensis hybrids).” Invasive Species Technical Note No. MT-13. U.S. Department of Agriculture, Natural Resources Conservation Service. Bozeman, MT, July 2007. http://www.mt.nrcs.usda.gov/technical/ecs/invasive/technotes/invasivetechnotemt13/. Kirk, McDaniel, and Mark Renz. “Saltcedar Information, Biology and Ecology.” Weed Information, New Mexico State University, Las Cruces, n.d. http://agesvr1.nmsu.edu/saltcedar/Index.htm. Martin, Tunyalee. “A Success Story: Tamarisk Control at Coachella Valley Preserve, Southern California.” Wildland Invasive Species Program, Nature Conservancy, January 2001. http://www .invasive.org/gist/stories/ca003/ca003.PDF. Zouhar, Kris. “Tamarix spp.” In Fire Effects Information System, U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, 2003. http://www.fs.fed.us/ database/feis/.

n Tree of Heaven Also known as: Ailanthus, Chinese sumac, copal-tree, stinking shumac, varnish tree Scientific name: Ailanthus altissima Synonyms: Toxicodendron altissima, Albonia peregrina, Ailanthus glandulosa, Ailanthus peregrina Family: Quassia (Simaroubaceae) Native Range. China, except the extremely arid central region. Distribution in the United States. Common in the East and Midwest, from Maine south to Florida, west to Texas, and north to Iowa and Wisconsin. Distribution in western and Great Plains states is discontinuous, often in riparian zones, from New Mexico west to California and north to Washington State. Also in Idaho and Nevada, east to Nebraska and Kansas. Plants are often indicative of old mining sites or homesteads in California. Description. Tree of heaven is a deciduous tree that grows 40–100 ft. (12–30 m) tall. It has one main trunk and is not shrubby. The smooth gray bark is vertically streaked, becoming fissured with age. The stout twigs form a broad, spreading lacy crown with few branches.

586 n TREES Shoots are initially covered with yellow-brown hairs, but old twigs are hairless. Leaves, which reach 4 ft. (1.2 m) long, are alternate and pinnately compound with 11–41 pointed leaflets, including a terminal leaflet. The lance-shaped leaflets are 2–6 in. (5–15 cm) long. Each leaflet has 2–4 rounded teeth near its base, while the rest of the leaflet has a smooth margin. Each tooth on the leaf base has a round gland on the underside. The upper leaf surface is deep green, while the underside is grayish green. When leaves fall, they leave a prominent scar on the stem, variously shaped like a heart, horseshoe, or shield. Male flowers and crushed foliage release an unpleasant odor, variously described as peanuts, cashews, or rancid nut oil. Depending on the soil texture, trees may have both a deep tap root and long lateral roots. The root system is strong and aggressive. In late spring or early sumPresent in most states except the northern Great Plains, tree of heaven mer, April to July depending on grows well in poor conditions, including nutrient-deficient soils, salt geographic location, small spray, and drought. (Native range adapted from USDA GRIN and selected greenish star-shaped flowers references. Introduced range adapted from USDA PLANTS Database, appear on 2.5–5 in. (6–12 cm) Invasive Plant Atlas of the United States, and selected references.) long panicles at the ends of new branches. Flowers have five overlapping sepals and five petals, 0.08–0.1 in. (2.0–2.5 mm) long. The base of each flower is slightly hairy. Male and female flowers are produced on different trees. Fruits mature from August to October and remain on the tree into winter. Fruits go through a color change as they ripen, first green, then becoming yellow, pink or orange, red, and red-brown. The 1–2 in. (2.5–5 cm) long dry fruits contain one small seed in the center of two flat wings. The fruit masses hang down, and trees with no fruit are males. Related or Similar Species. Several plants native to the eastern United States which have large, compound leaves may be mistaken for tree of heaven. Native trees have serrated or toothed leaflet margins, distinct from the smooth leaflet margins of tree of heaven. Staghorn sumac may further be distinguished from tree of heaven by its fuzzy reddishbrown branches and red, fuzzy fruits that are borne erect rather than pendant.

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A. Tree of heaven is a tall tree with one main trunk. (Karan A. Rawlins, University of Georgia, Bugwood.org.) B. The large compound leaves have many leaflets. (Paul Wray, Iowa State University, Bugwood.org.) C. The trunk becomes fissured with age. (Annemarie Smith, ODNR Divison of Forestry, Bugwood.org.) D. Leaf scars are prominent, with a distinct shape. (Daniel Herms, Ohio State Weed Lab Archive, The Ohio State University, Bugwood.org.) E. Small star-shaped flowers grow on long panicles. (Jan Samanek, State Phytosanitary Administration, Bugwood.org.) F. The base of each leaflet has 2–4 distinct teeth. (James H. Miller, USDA Forest Service, Bugwood.org.) G. Each winged pod contains one seed. (Annemarie Smith, ODNR Divison of Forestry, Bugwood.org.)

Introduction History. Tree of heaven has a long history in the United States. A gardener in Philadelphia imported the plant in 1784, and by 1840, it was commonly available in nurseries, probably because it was easy to grow under poor conditions. Chinese immigrants introduced the tree to California during the gold rush in the 1890s. Habitat. Tree of heaven is a fast-growing pioneer tree that generally needs sunlight, but may tolerate some shade. The tree thrives in poor soils, including limestone, and tolerates airborne salt and drought. It predominantly invades wastelands, seminatural areas, or disturbed areas, including grassland, forest openings, riparian locations, and rocky outcrops. In urban locations, it is commonly seen in disturbed sites such as alleys, sidewalks, parking lots, and is so frequent that it is almost “natural.” In rural areas, it is found in fields, fencerows, roadsides, forest edges and clearings. It frequently forms thickets at the edges of forests and will fill in any clearings that develop. Due to extensive root suckering, it can form dense thickets covering an entire acre. Tree of heaven is also an agricultural pest. Seedlings by the hundreds can sprout in newly planted fields. While older trees can resist freezing temperatures, plants younger than six years are susceptible to frost. Regardless of age, leaves fall at the first frost. In the western states, the tree grows below 6,600 ft. (2,000 m) elevation. Reproduction and Dispersal. Tree of heaven reproduces both sexually and vegetatively. Plants flower early in their life, sometimes only six weeks after germination. Each female tree may produce 325,000 seeds annually and live for 50 years. Dissemination of seeds is primarily by wind, the wings on the seeds acting like small propellers. Seeds are also spread by water, birds, vehicles, and machinery. Seeds remain viable for one year. They have a high germination rate and develop a tap root within three months. If the soil is clay or compacted, long lateral roots develop instead. Trees grow quickly in full sunlight, as much as 3.3 ft. (1 m) per year for the first four years.

588 n TREES When the trunk is cut, suckers resprout vigorously from the stump and from roots. Root sprouts can emerge 50 ft. (15 m) from the mother plant, even through sidewalk cracks or other concrete. Impacts. Tree of heaven thickets displace natural vegetation, especially in riparian habitats, and toxins from leaf litter prevent native plants from reestablishing. Litter is toxic to 35 species of gymnosperms and 10 species of angiosperms, severely limiting competition and natural succession. In urban areas, the aggressive root system may damage sidewalks, sewers, and foundations. Sucker growth poses maintenance problems for landscapers. Management. Because this species vigorously resprouts, the most important management aspect is to frequently monitor sites for regrowth and pull or treat new sprouts or seedlings as they occur. Sites should be checked at least once a year, preferably more often. Targeting large female trees will help to reduce seed production. Any physical means of removal must involve the whole plant, because any root fragments will sprout. Small plants, especially seedlings, can be pulled or dug up. Although it is possible to remove entire seedlings, including roots, removing the root from root suckers is not as simple. Chopping, cutting, or mowing plants, either manually or mechanically, encourages sprouts. Cutting should be done in early summer or just before flowering when root reserves are lowest. Burning the trunks or stems with a flamethrower, which can be done during wet weather and snow conditions to avoid wildfires, can be used for spot treatment. However, plants will resprout. Grazing will remove tops of seedlings and sprouts, thereby preventing flowering. With repetition over several years, grazing, cutting, or burning may deplete root storage and weaken plants. Although no studies have been specific to tree of heaven, chemical applications provide the most effective control. Herbicides may be applied to leaves, basal bark, or cut stumps. Chemicals are especially necessary on cut stumps to prevent resprouting. It is easy to kill the above-ground parts of the plants, but roots are much more difficult. Both glyphosate and triclopyr are systemics, meaning that the chemicals are translocated to the roots, with no residue in the soil. Because glyphosate is nonselective, it cannot be sprayed onto foliage in mixed stands where native vegetation would also be damaged. In contrast, triclopyr is selective; it will affect broadleaf and woody plants but will not harm grasses. Basal bark application, which works well on trees less than 6 in. (15 cm) in diameter, is the easiest method because no cutting is involved. It is most effective when done in late winter or early spring. During late spring or early summer, plants are moving fluids upward to grow, not down into the roots. An alternative is hack-and-squirt. After making down-angled cuts into the trunk, squirt triclopyr into the cut. Girdling the trunk is not recommended without follow-up herbicide treatment because it triggers a survival response of vigorous sprouting and suckering in the plant. After a trunk is cut to a stump, herbicide must be applied within

Beneficial Uses of Tree of Heaven

B

ecause of its tolerance for poor soils, tree of heaven has been used for revegetating acidic mine spoils where the pH is less than 4.1. It is ideal for urban and industrial areas because it tolerates pollution, including particulates like cement dust and gases from the coke and coal-tar industry. The leaves absorb sulphur and mercury, and the plant is resistant to ozone. The book A Tree Grows in Brooklyn, by Betty Smith in 1943, is based on Ailanthus.

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5–15 minutes, before the plant seals off the area. It is labor intensive to cut trees before treatment, unless the area must be cleared anyway. Little research has been conducted on biological control of tree of heaven. However, a potential exists in fungal pathogens (Verticillium dahliae and Fusarium oxysporum) found on dead or dying plants in New York and Virginia. A possibility also exists in the use of the zonate leafspot (Cristulariella pyramidalis) for defoliation.

Selected References Hoshovsky, Marc C. “Element Stewardship Abstract, Ailanthus.” Global Invasive Species Team, Nature Conservancy, 1988. http://invasive.org/gist/esadocs/documents/ailaalt.pdf. Swearingen, Jil M., and Phil Pannill. “Tree of Heaven.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2005. http:// www.invasive.org/gist/esadocs/documnts/ailaalt.pdf. “Tree-of-Heaven.” Invasive Species Identification Sheet, U.S. Department of Agriculture Natural Resources Conservation Service. Tolland, CT, 2002. http://www.ct.nrcs.usda.gov/tree-of -heaven.html.

n Velvet Tree Also known as: Miconia, purple plague, bush currant Scientific name: Miconia calvescens Synonyms: Cyanophyllum magnificum, Miconia magnifica Family: Melastome (Melastomataceae) Native Range. Central and South America, from southern Mexico at 20º N latitude to northern Argentina and southern Brazil at 25º S latitude. It grows as high as 6,000 ft. (1,830 m) elevation in Ecuador. The form with the very large leaves and purple undersides is native only to Mexico and Central America, including Guatemala, Belize, and Costa Rica. Distribution in the United States. The major islands of Hawai’i. Some reports of naturalization in Puerto Rico. Description. Velvet tree is a shrubby evergreen tree, with many slender branched stems that grow vertically. The tree can reach 45 ft. (13.5 m) tall. The oval leaves, opposite on the stem, can be very large, up to 3 ft. (1 m) long. Although they may appear velvety, leaves have no hairs. In contrast to the dark-green upper surface of the leaf, the underside is an iridescent purple. Leaves are further distinguished by three prominent veins running from the base to the tip, one in the center of the leaf and one closer to each leaf margin. These veins are connected by many smaller veins running crosswise on the leaf. The root system is shallow. The inflorescence is a large erect panicle with 1,000–3,000 small white to pink or tan flowers. The sweetly scented flowers each live for only 12–24 hours. The small, 0.25–0.5 in. (6–13 mm) diameter, dark-blue or purple fruit is sweet and attractive to birds. Each fruit contains many small seeds, each about the size of a grain of sand. Related or Similar Species. Eight additional members of the Melastome family are present in Hawai’i, the worst being Koster’s curse or soap bush (see Shrubs, Koster’s Curse), cane ti or cane tibouchina, and bristletips. Both cane ti and bristletips are much smaller plants. Cane ti, native to Brazil, Paraguay, and Uruguay, is a branched upright shrub, as tall as 9 ft. (2.7 m). Leaves are 3 in. (7.5 cm) long and hairy, with 5–7 prominent longitudinal veins. The four-petaled flowers are pink with bright yellow anthers. A second shrub

590 n TREES species of Tibouchina, glorybush or princess flower, which is also native to Brazil, has purple flowers with five petals. Glorybush is less invasive because it does not seem to spread by seed. Native to the Himalayas and southwestern China, bristletips is a shrub 6.5–13 ft. (2– 4 m) tall with drooping branches. Leaves are 3–6 in. (8–16 cm) long with five parallel veins. Leaves are generally glabrous, but veins on the lower surface are covered with stellate hairs. Pinkish-purple flowers, 0.75 in. (2 cm) long, grow in pendulous clusters. Introduction History. Velvet tree was deliberately brought to the Wahiawa Botanical Garden in central O’ahu in 1961, and also to Waimea Botanical Garden in northwestern O’ahu. Both of those plantings were in seasonally dry areas of the island, with 59–65 in. (1,500– 1,650 mm) annual rainfall. A tree was planted at Harold L. Lyon Arboretum near Honolulu in 1964, and another Velvet tree is a very destructive invader of tropical rainforest habitats on tree was planted near the same Pacific islands, including Hawai’i. (Native range adapted from USDA area in the late 1970s or early GRIN and selected references. Introduced range adapted from USDA 1980s. In spite of the fact that PLANTS Database, Invasive Plant Atlas of the United States, and selected the original trees were destroreferences.) yed in the 1990s when the invasive nature of the tree was realized, velvet tree has become naturalized on O’ahu. A plant was introduced to a private estate on the island of Hawai’i in the early 1960s, and a specimen was taken to a private nursery and botanical garden on Mau’i in the early 1970s. Infestations on Kaua’i stem from a single seedling imported from O’ahu. Velvet tree was sold in nurseries because of its attractive foliage until it was declared a Hawai’i noxious weed in 1992. Habitat. Capable of growing in several habitats, including coastland, scrubland, and riparian sites, velvet tree occupies the tropical montane zone in Hawai’i, where the forests receive 70–80 in. (1,800–2,000 mm) of annual precipitation. Usually found between 1,000 and 5,900 ft. (300–1,800 m) elevation, it can grow as high as 6,500 ft. (2,000 m) elevation, as well as in lower elevations, and is a threat to habitats up to the upper limit of forest growth. It is quick to invade following deforestation due to fire, overgrazing, or other

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A. Velvet tree has destroyed much of the natural forest in Tahiti. (The Nature Conservancy Archive, Bugwood.org.) B. The large leaves have distinctive veins. (Forest and Kim Starr.) C. The inflorescence is a large panicle. (Forest and Kim Starr.) D. Veins are prominent on the purple undersides of leaves. (Forest and Kim Starr.)

disturbances, but can also invade intact, healthy forests. It is especially invasive on fallow land from abandoned sugarcane plantations, from where it can spread into adjacent upland forests. In Tahiti, it rapidly invaded forests damaged by hurricanes. The tree prefers to grow on mineral soil, dead tree trunks, and dead fern trunks, and is very shade tolerant. Reproduction and Dispersal. Plants produce flowers and fruit when they are 4–5 years old and about 12 ft. (3.7 m) tall. Each mature tree, taller than 26 ft. (8 m), can flower three times a year, With 220 inflorescences, 200 fruits per inflorescence, and 50–200 seeds per fruit, trees can produce 2–3 million seeds each time they flower. The soil seedbank is huge and may be more than 5,000 seeds per sq. ft. (50,000 per m2). Seeds remain viable for 5– 10 years. Seeds are dispersed predominantly by birds, and somewhat by rodents, which eat the fruit. Birds can carry thousands of seeds long distances, as far as 1.25 mi. (2 km). Seeds are dispersed predominantly by nonnative bird species, such as the Japanese White-eye, Common Myna (see Volume 1, Vertebrates, Birds, Common Myna), and the Red-billed Leiothrix. Seeds are also spread by human activities, by adhering to shoes or clothing, machinery, and vehicles, or being transported in soil or garden waste. Seeds can also cling to hooves of livestock. Seeds may be spread on native tree fern logs that are transported between islands. Seedlings can germinate in either sun or deep shade, with as little as 0.02 percent of available sunlight. Moisture, however, appears to be a limiting factor. Seeds lose viability when they become dry. Under good conditions, juvenile trees can grow 5 ft. (1.5 m) per year. Impacts. Velvet tree is considered to be one of the most destructive invaders to tropical rainforest habitats on the Pacific Islands, including Hawai’i. It is successful because it grows rapidly, reaches maturity early, and produces abundant seeds that are widely dispersed. If not stopped, it will threaten almost all the mesic and wet forests in Hawai’i that receive more than 60 in. (1,500 mm) of annual rainfall. It alters habitat, changes hydrology, and may contribute to soil erosion. Velvet tree forms dense monospecific stands that shade out and displace native plants, decreasing the biodiversity of the ecosystem, threatening endangered species, including plants, birds, and invertebrates. Velvet tree thickets threaten to replace ohia and koa forests, endangering rare native Hawaiian birds and insects, which depend on that habitat.

592 n TREES Velvet tree alters the hydrology. Dense thickets create an umbrella-like canopy over the watershed, reducing infiltration and groundwater recharge, resulting in more runoff. Because its roots are shallow, landslides and erosion are more likely where velvet tree displaces native plants. With less infiltration of rainfall, more runoff increases erosion, which in turn increases siltation, changing the quality of surface water. Estimates of costs due to reduced groundwater recharge and to changes to water quality on O’ahu approach $145 million per year. Loss of topsoil through soil erosion reduces nutrients and organic matter, which in turn lowers agricultural productivity. Economic losses for the worst-case scenario of damage to water and erosion on all the Hawaiian Islands are potentially $380 million per year. Management. Control or eradication of velvet tree requires a sustained effort. Because seeds are easily carried in clothing and equipment, people should change clothing and shoes after working in an infested area. All equipment, including anything that might carry seeds, should be thoroughly cleaned. Physical control is possible with small trees or saplings, less than 10 ft. (3 m) tall, that can be pulled or uprooted. Although it is unusual, uprooted trees left lying on the soil may grow adventitious roots. Cutting down trees, or removing the canopy, triggers germination of seedlings, which can be 40–100 per sq. ft. (400–1,000 per m2), all less than 2.3 ft. (0.7 m) tall, after 18 months of growth. These smaller trees may then be sprayed with a herbicide, repeated in 2–3 years until the seed bank is exhausted. Chemical control is the most effective. Triclopyr applied to foliage, cut stump, or basal bark is best. When applied to cut stumps, triclopyr + 2,4-D has resulted in few resprouts. In inaccessible areas such as steep slopes or rugged lava flows, aerial spraying of herbicides has had 70 percent success on fruiting trees, but it is expensive and threatens nontarget plant species. A range of biological agents from Latin America that damage velvet tree, including fungi, weevils, beetles, nematodes, wasps, butterflies, and moths, is being studied. Because Hawai’i has no native plants in the Melastome family, it is more likely that introduced pests will be host-specific to velvet tree. Chinese rose beetle (Adoretus sinicus) causes 50 percent defoliation but does not kill the tree. A defoliating sawfly (Atomacera petroa), which attacks leaves, has good potential because it is highly host-specific. A leaf spot disease caused by Cocostroma myconae is also a possibility. A gall wasp (Allorhogas sp.) and a beetle (Apion sp.) that both feed on the fruit are being evaluated in Brazil for host preferences. A fungus (Colletotrichum gloesporioides f. sp. miconiae), which causes leaf spotting and leaf drop, is now present on Hawai’i and Mau’i.

Velvet Tree in Tahiti

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elvet tree was introduced to Tahiti in 1937, possibly from Sri Lanka by the botanist J. F. Rock who worked extensively in botanical gardens in Asia. It now dominates over 65 percent of the island’s forest cover, and has displaced native species due to its deep shade-producing foliage. Tahiti and Hawai’i are similar in topography and climate, both being volcanic islands with heavy rainfall at a similar distance from the equator. If not checked, velvet tree has the potential to severely and irreparably alter Hawai’i’s botanical landscape as it has done to Tahiti.

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Selected References “HNIS Report for Miconia calvescens.” A product of the Hawaiian Ecosystems at Risk Project (HEAR), 1997. http://www.hear.org/hnis/reports/HNIS-MicCal.pdf. Medeiros, A. C., L. L. Loope, P. Conant, and S. McElvaney. “Status, Ecology, and Management of the Invasive Plant, Miconia calvescens DC (Melastomataceae) in the Hawaiian Islands.” Records of the Hawaii Biological Survey for 1996. Bishop Museum Occasional Papers 48: 23–36, 1997. http:// hbs.bishopmuseum.org/pdf/melastome97.pdf. Motooka, P., L. Castro, D. Nelson, G. Nagai, and L. Ching. “Miconia calvescens.” In Weeds of Hawai’i’s Pastures and Natural Areas: An Identification and Management Guide. College of Tropical Agriculture and Human Resources, University of Hawai’i, Manoa, 2003. http://www.ctahr.hawaii.edu/invweed/ WeedsHI/W_Miconia_calvescens.pdf. National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG). “Miconia calvescens (Tree).” ISSG Global Invasive Species Database, 2006. http://www.issg .org/database/species/ecology.asp?fr=1&si=2. Wise, Andrea, and Robert E. Lyons. “Velvet Tree.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2009. http://www.nps.gov/plants/ alien/fact/mica1.htm.

n Vines n Chocolate Vine Also known as: Five-leaf akebia Scientific name: Akebia quinata Synonyms: Rajania quinata Family: Lardizabala (Lardizabalaceae) Native Range. East-Central China to Korea and Japan. Distribution in the United States. Eastern and midwestern states, from New York and Massachusetts south to Georgia, west to Louisiana, and north to Missouri, Illinois, and Michigan. Description. Chocolate vine is a vigorous trailing ground cover or climbing woody vine that grows fast. The vines climb by twisting or twining stems around the host, and their height is restricted only by the structures or plants they climb. Plants are deciduous in cooler climates, but evergreen where winters are warmer. The slender round stems are green when young, but mature to grayish brown, with small, round lenticels. Bud scales are light reddish brown. Palmately compound leaves are alternate on the stem. Five or fewer oval leaflets, 1.5–3 in. (4–7.5 cm) long and slightly notched at the tip, grow on small stalks that merge in the center of the compound leaf. Leaflets are dull blue-green with a purplish tinge that turns to blue-green when the leaves mature. Flowering occurs from late March to early April. The reddish to chocolate-purple color flowers, 1 in. (2.5 cm) in diameter, are fragrant, with a vanilla or chocolate scent. Both male and female flowers grow on racemes from leaf axils. The two slightly smaller flowers at the end of the racemes are male, while the remainder are female. The ball-shaped buds unfold three broad sepals to form a cup holding the inner flower parts. Fruit ripens from late September to early October. The purple-violet seed pods resemble 2.5–4 in. (6–10 cm) long, flattened sausages. Pods split when mature, revealing a whitish pulpy interior with many tiny black or brownish seeds arranged in irregular rows. Related or Similar Species. A related species with three leaflets, three-leaf akebia, is also native to China. A hybrid occurring in Massachusetts, which is a cross between five-leaf akebia and three-leaf akebia, has 3–5 leaflets. Two species of Aristolochia common in the southern and eastern part of the United States are also climbing vines. Both pipevine and wooly Dutchman’s pipe are easily distinguished by having simple (not compound) heart-shaped leaves and flowers that resemble a pendulant curved pipe. Introduction History. Chocolate vine was introduced to the United States in 1845 as an ornamental, for its attractive purplish foliage. Because it rarely sets seed, its escape from cultivation, especially over long distances, was probably aided by humans. Both species and the hybrid, as well as cultivars with different color flowers, are available through Internet nurseries. Habitat. Chocolate vine grows in many habitats, including riparian, urban, and wetland sites, but it also tolerates drought. Plants grow best in partial shade, especially on northern aspects, but they can also do well in full sun. Because it is shade tolerant, the vine can invade healthy forests. It

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grows on various soil textures, from light to heavy, including sandy, loamy, and clay. Plants prefer well-drained but moist soils that may be either acid or alkaline. Although dormant plants are hardy to −4ºF (−20ºC), young spring growth will be killed by frost. In its native China, chocolate vine grows from 1,000 to 5,000 ft. (300– 1,500 m) elevation. Reproduction and Dispersal. Reproduction of chocolate vine is primarily vegetative because vines do not self-pollinate well. Both fruit and flowers are uncommon outside of cultivation. Vines, which root where they touch the ground, can grow as much as 20–40 ft. (6– 12 m) in one growing season. Birds eat the fruit and disperse the seeds, but most spread of chocolate vine is done by humans. Seeds germinate within 1–3 months at temperatures of 59ºF (15ºC). Plants require five years to mature to flowering and fruiting stage, but the life span is unknown. Impacts. Chocolate vine nat- This shade-tolerant vine, which thrives in a variety of habitats, can inuralizes easily and can overrun vade healthy forests, especially in the mid-Atlantic states. (Native range and smother ground-level adapted from USDA GRIN and selected references. Introduced range herbs, seedlings, saplings, and adapted from USDA PLANTS Database, Invasive Plant Atlas of the United States, and selected references.) understory shrubs because of its rapid growth. Its dense growth, a mat of impenetrable vines, prevents the germination and establishment of native plants by depriving them of light, water, nutrients, and space. If left unchecked, plants can even kill canopy trees by overtopping and smothering them. Management. Because chocolate vine will sprout from its roots, any control requires follow-up to eliminate resprouts. Physical control may be accomplished by repeatedly cutting the stems during the growing season to exhaust nutrient reserves in the roots. If available personnel and money allow only one cutting to be done, plants should be cut to the ground at the end of summer. Groundcover vines may be either left on site or disposed of elsewhere. Detached vines will not root and grow. Vines that climb trees or buildings may also be severed from the roots. Remaining roots from either growth type must be either dug out or treated with herbicides to prevent resprouting. Small plants, including the root, can be totally removed.

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A. Vines climb into the canopy of trees. (Chris Evans, River to River CWMA, Bugwood.org.) B. Compound leaves have five oval leaflets. (James H. Miller, USDA Forest Service, Bugwood.org.) C. Small flowers have three sepals. (Nancy Loewenstein, Auburn University, Bugwood.org.) D. Young vines are slender. (James H. Miller, USDA Forest Service, Bugwood.org.) E. Older vines are thicker, with lenticels. (James H. Miller, USDA Forest Service, Bugwood.org.) F. Seed pods resemble small sausages. (James H. Miller, USDA Forest Service, Bugwood.org.)

Mulching is effective for small areas of trailing chocolate vine on the ground or where herbicides cannot be used. Plants can be covered with several inches of any biodegradable material, such as grass clippings, hay, or wood chips. Hay and grass clippings, however, may be contaminated with other weed seeds. An additional covering of cardboard over the mulch will impede its decay and prolong its life. Mulching should be done for two growing seasons, refreshing the cover as necessary. Mulching can also be done after herbicide treatment as an extra precaution against regrowth. Chemical application of herbicides by spraying the foliage is practical for large stands where soil disturbance caused by uprooting plants would be too disruptive to the site. Triclopyr ester is a more effective foliar spray than is glyphosate, and is also absorbed through any bark it reaches. To avoid damage to native species, spraying should be done before native wildflowers emerge. Triclopyr ester applied to basal bark, after vines have been stripped away to allow access, affords good control, but care should be taken to avoid dripping the herbicide on the bark of the host tree. Stems of climbing vines may be cut close to the ground and again slightly higher to ensure a complete separation of roots from the climbing vines. The severed vines will die, rot, and fall off the tree or structure. Apply triclopyr amine or glyphosate to the cut stems to protect against sprouts. No biological controls are currently available for chocolate vine. Four species of fungus (Microsphaera akebiae, Microsphaera penicillata, Muyocopron smilacis, and Aecidium akabiae) are associated with chocolate vine in its native China. Three moths (Evecliptopera decurrens, Ophideres fullonica, and Archips asiaticus) can damage the plant. The most common, however, is Ophideres fullonica, a fruit-piercing moth, which is a serious pest in orchards.

Selected References National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG). “Akebia quinata (Vine, Climber).” ISSG Global Invasive Species Database. 2005. http:// www.issg.org/database/species/ecology.asp?si=188&fr=1&sts.

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Uses of Chocolate Vine

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hocolate vine, including stems, roots, and fruit, is an ancient traditional medicinal plant in China. The sweet, edible fruit is used in wine making, and the soft, young shoots may be eaten either pickled or raw in salads. Leaves are steeped for a type of tea. When ingested, some plant parts control bacterial and fungal infections, such as those of the urinary tract. The plant is also used to induce menstruation and lactation and for reducing fever. Oil from the seed is used for making soap.

Swearingen, Jil M., Adrienne Reese, and Robert E. Lyons. “Fiveleaf Akebia.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2006. http://www.nps.gov/plants/alien/fact/pdf/akqu1.pdf. Zheng, Hao, Yum Wu, Jianqing Ding, Denise Binion, Weidong Fu, and Richard Reardon. “Akebia quinata.” In Invasive Plants of Asian Origin Established in the United States and Their Natural Enemies. U.S. Department of Agriculture, Forest Service. FHTET-2004-05, 2004. http://www.invasive.org/weeds/ asian/akebia.pdf.

n Climbing Ferns Japanese Climbing Fern Also known as: No other names Scientific name: Lygodium japonicum Synonyms: Ophioglossum japonicum Old World Climbing Fern Also known as: Small-leaf climbing fern Scientific name: Lygodium microphyllum Synonyms: Lygodium scandens, Ugena microphylla Family: Climbing Fern (Lygodiaceae) Native Range. Japanese climbing fern is native to eastern Asia, from India east through Southeast Asia, eastern China, Japan, Korea, the Philippines, and Indonesia east to New Guinea. Old World climbing fern is from the Old World Tropics, sub-Saharan Africa, India, and thoughout Southeast Asia, southeastern China, the Philippines, Indonesia east to New Guinea, northern Australia, and some western Pacific islands. Distribution in the United States. Japanese climbing fern is found in the southeastern states, from Texas east to Florida, and north to North Carolina. Also in Pennsylvania, Hawai’i, and Puerto Rico. Old World climbing fern is limited to southern Florida. Description. Although both species are ferns, with distinct terminology for their vegetative parts, their overall structure resembles stems and leaves. Both climbing fern species are vine-like perennials that climb onto and over shrubs, trees, or structures. The slender twining stems, which may be 90 ft. (30 m) long, are green, orange, or black. All stems are wiry and difficult to break. Although both species have light-green compound leaves, opposite on the stem, the leaves are different. Japanese Climbing Fern: Leaves of Japanese climbing fern are doubly compound and vary in appearance. The overall shape of the compound leaf is triangular, 3–6 in. (8–15 cm) long and

598 n VINES 2–3 in. (5–8 cm) wide. Leaflets grow on stalks and are lobed. Terminal lobes of the leaflets are often very finely dissected, appearing lacy or feathery, while the basal lobes on the same leaflet may be either dissected or irregularly lobed. The lower surface of the leaves is pubescent, with short curved hairs. In climates where temperatures drop below freezing, leaflets die in winter, but they may remain green in sheltered places. The dry, brown fronds and stems remain in place, providing a trellis for new growth the following season. Slender, creeping rhizomes, which are actually the fern stems, are dark brown or black. They form a mat, 0.4–1.2 in. (1–3 cm) below the surface. While leaflets on the lower part of the stems are sterile and toothed, leaflets higher on the stem become successively more fertile as the vine grows longer. The fertile leaves, or fronds, are usually smaller. The leaf margins of fertile fronds have lobelike projections containing two Japanese climbing fern, not considered a wetland species, commonly rows of sporangia (structures invades open forests and roadsides in the southeastern states. (Native enclosing spores). Slightly rollrange adapted from USDA GRIN and selected references. Introduced ed leaf margins partially cover range adapted from USDA PLANTS Database, Invasive Plant Atlas of the the sporangia. The nearly micUnited States, and selected references.) roscopic spores are dispersed during late summer and early fall. Old World Climbing Fern: Leaves of Old World climbing fern are once compound, 2–5 in. (5–12 cm) long, with an oblong outline. Leaflets are leathery, usually not lobed, and glabrous or waxy on the lower surface. When the leaflet is detached, the wiry stalk remains attached to the stem. Restricted to warmer climates, Old World climbing fern does not die back in winter, continuing to produce vegetative growth and fertile leaflets. A dense mat of rhizomes may be 3 ft. (1 m) or more thick on the top of the soil. Fertile leaflets are the same size as other leaflets, with a tiny lobed fringe of slightly folded leaf tissue covering sporangia. Sterile fronds have entire margins. Related or Similar Species. Growing in wetlands throughout most states east of the Mississippi River, the rare American climbing fern is the only Lygodium species native to

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North America, where it is threatened or endangered. Its distinctly palm-like leaflets are easily recognized by the 5–7 fingerlike lobes. Introduction History. Both species have been cultivated in Florida as garden plants. A species of climbing fern, advertised as Old World but probably Japanese, was offered for sale in a nursery catalog as early as 1888. Japanese climbing fern was known to be naturalized in Georgia by 1903. The species is still recommended as a garden ornamental and sold on the Internet. Although the date and manner of introduction of Old World climbing fern is not known, the first naturalized specimen was collected in Florida in 1965. Since that time, the plant has spread rapidly to cover thousands of acres, including several counties and the Everglades, and is expanding its range northward. Habitat. Both plants are limited to warm temperate or tropical areas, usually growing on damp or disturbed sites, in Old World climbing fern, restricted to warm climates, is a major threat to either sun or shade. Little is the Everglades ecosystem. (Native range approximated from USDA GRIN known regarding specific habi- and selected references. Introduced range adapted from USDA PLANTS tat requirements. Neither spe- Database, Invasive Plant Atlas of the United States, and selected cies grows in very dry soils or references.) under long-term flood conditions, but both tolerate fluctuating water levels. Infestations in remote environments in the Everglades indicate that neither species requires human disturbance to become established. Although both are found in somewhat similar environments, Japanese climbing fern is not considered to be a wetland species. It is commonly found in yards and along roadsides, but also in moderately disturbed areas in open forests and at the margins of wetlands, such as swamps, lakes, and creeks. It may also be scattered in tree plantations. Old World climbing fern is found in both wetland and mesic habitats and is common in bald cypress swamps, hammocks, pine flatwoods, wet prairies, mangrove communities, and disturbed sites. Populations of Old World climbing fern in sawgrass marshes grow on slightly elevated mounds or on tree trunks or rotting logs. This species seems to be limited in its northern extent by minimum winter temperatures of 39–44ºF (4–6.5ºC). The potential

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A. Infestation of Old World climbing fern. (Amy Ferriter, State of Idaho, Bugwood.org.) B. Foliage of Japanese climbing fern. (Chris Evans, River to River CWMA, Bugwood.org.) C. The ferns climb by twining their stems around objects. (Richard Old, XID Services, Inc., Bugwood.org.) D. Fertile frond of Japanese climbing fern. (Richard Old, XID Services, Inc., Bugwood.org.) E. Pieces can be dispersed in pine straw bales collected from areas where Japanese climbing fern exists. (Dennis Teague, U.S. Air Force, Bugwood.org.) F. Fertile frond of Old World climbing fern. (Amy Ferriter, State of Idaho, Bugwood.org.)

for spores to be transported northward along the moderate climate regions of the Atlantic coast and westward along the Gulf coastline would greatly increase its range. Reproduction and Dispersal. Both climbing ferns reproduce by wind-dispersed spores. Spores may also be carried long distances as a component of dust on vehicles and other objects. Although spores may germinate in 6–7 days, dried spores are able to germinate after two years. The young fern initially resembles a small liverwort before it grows leafy fronds. The creeping rhizomes enable the plant to spread locally. Plants resprout after winter frosts and after vines are burned. Impacts. Both species grow as either individual plants or tangled masses of stems and leaves that cover the ground, shrubs, and even tall trees. They form dense mats of old and new stems and fronds that smother native vegetation, lowering the biodiversity of the community. The dense canopy blocks sunlight, with mats as thick as 10 ft. (1 m) that do not allow native plants to grow through. Hammocks in the Everglades may be so engulfed by climbing fern that the plants beneath cannot be seen. Both species intensify fires due to the added fuel load and, because of their climbing habit, carry fire into the tree canopy. Native bromeliads growing on tree trunks are destroyed. The dry leaflets of Japanese climbing fern and wind-blown burning fragments are additional fire hazards. Japanese Climbing Fern: Japanese climbing fern threatens three species on the Florida endangered list, a perennial shrub called Georgia bully, wooly Dutchman’s pipe (a vine), and branched tearthumb (a forb). Although the effect on wildlife is believed to be significant, no data are yet available. Old World Climbing Fern: Because Old World climbing fern is restricted to warmer climates and does not die back in winter, the accumulation of its stems and leaves can grow to massive proportions. It can form a monoculture in cypress swamps and other wet areas, where it displaces all the native plant and animal species, completely disrupting the ecosystem. Several rare plants, such as tropical curlygrass fern, giant air plant (also called giant wild pine), and other bromeliads, are severely threatened as Old World climbing fern invades their last remaining habitats. Because of its potential to spread, not just in Florida but to other subtropical areas of the Gulf coast and into Mexico and Central America, Old World climbing fern is considered to be a serious danger to subtropical ecosystems.

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Old World climbing fern is a serious problem in Florida pine plantations, where it not only complicates harvesting, but may also become a contaminant in pine straw. The use of pine straw, which is freshly fallen pine needles, in landscaping may inadvertently introduce both spores and fragments of Old World climbing fern into home gardens and new regions. In one investigation, approximately 25 percent of the pine straw bales sold in nurseries were contaminated. Economic costs of eradicating the ferns from natural areas or managed lands are high. Control costs in 2000 were $135–500 per acre ($330–1,250 per ha), but one application in a remote location cost $1,520 per acre ($3,750 per ha). The climbing ferns, however, grew again, and the area had to be retreated in 2001. Management. Areas should be consistently monitored to prevent new infestations. In existing sites, prevention of spore formation and dispersal is important to minimize the spread of climbing ferns into new areas. Because the tiny spores are easily transported, control activities should be undertaken at times of the year when spores are not being produced or dispersed. If work must be done at that time, avoid driving equipment through the fern area. To reduce the risk of spreading spores or plant pieces, workers should not go to other areas on the same day. Physical efforts on small plants or small areas may be done by hand-pulling or cutting, but new vines will grow from the rhizomes. Machines can be used to pull large mats off vegetation, but doing so may damage the understory soil and vegetation. Fire is a poor option, not only because new stems will grow from the rhizomes, but the climbing vines will pull the fire into tree canopies and do more damage. Little research has been conducted on chemical controls. Glyphosate, imazapyr, and metsulfuron methyl are all effective, either in combination or alone. Imazapyr causes the greatest damage to nontarget species, including large hardwood trees. Herbicide applications are best done during July through October. Because only one species of Lygodium is native to the United States, and in a different climate zone, the possibility is good of finding a biological agent that is host-specific. Searches have been conducted in most of the native ranges of the alien climbing ferns. A West Indies Lygodium species, from Cuba, the Dominican Republic, and Haiti, may be an additional source. Most studies have been done on Old World climbing fern, including testing for possible damage to 40 species of threatened or endangered ferns in Florida. A South American rust (Puccinia lygodii), which has been found on Japanese climbing fern in northern Florida, has been studied in greenhouse settings, but it is unknown whether the rust occurs in the region infested by Old World climbing fern. The moth Neomusotima fuscolinealis is a native pest on Japanese climbing fern in Japan, but because it also attacks American climbing fern, it is unsuitable. A related tropical moth from northern Australia and Southeast Asia (Neomusotima conspurcatalis) defoliates plants but does not pose a threat to American climbing fern because it cannot tolerate cooler temperatures. It was cleared for release in 2007. In 2004– 2005, a defoliating moth (Austromusotima camptozonale) from Australia was released in several locations in Florida, but did not become established. Additional possibilities include a gall mite (Floracarus perrepae), lygodium saw fly (Neostrombocerus sp.), flea beetles (Manobia sp.), and stem borers.

Selected References MacDonald, Greg, Brent Sellers, Ken Langeland, Tina Duperron-Bond, and Eileen Ketterer-Guest. “Japanese Climbing Fern.” Center for Aquatic and Invasive Plants, University of Florida, 2009. http://plants.ifas.ufl.edu/node/639.

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The Genus Lygopodium

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he genus Lygopodium is ancient, its ferny fronds easily recognizable in the fossil record from the Upper Cretaceous geologic time period, contemporaneous with dinosaurs.

Miller, James H. “Japanese Climbing Fern.” In: Nonnative invasive plants of southern forests: a field guide for identification and control. Gen. Tech. Rep. SRS-62, U.S. Department of Agriculture, Forest Service, Southern Research Station, Asheville, NC, 2003. http://www.invasive.org/eastern/srs/ JCF.html. Minogue, Patrick, Stella Jones, Kimberly K. Bohn, and Rick L. Williams. “Biology and Control of Japanese Climbing Fern (Lygodium japonicum).” Publication #FOR 218. University of Florida IFAS Extension, n.d. http://edis.ifas.ufl.edu/fr280. Pemberton, R. W., J. A. Goolsby, and T. Wright. “Old World Climbing Fern.” In Biological Control of Invasive Plants in the Eastern United States, by R. Van Driesche et al. USDA Forest Service Publication FHTET-2002-04, 2002. http://wiki.bugwood.org/Archive:BCIPEUS/Old_World _Climbing_Fern.

n English Ivy Also known as: No other names Scientific name: Hedera helix Synonyms: None Family: Ginseng (Araliacaeae) Native Range. Western Europe, from Scandinavia south to the Mediterranean Sea, and east to the Ukraine, Turkey, and the Caucasus region. Possibly the Mediterranean countries of northern Africa and the Canary Islands and Madeira Islands. Distribution in the United States. Western states, Arizona, Utah, and Idaho and the Pacific coast. Midwestern, southern, and eastern states, from Texas and Oklahoma east to Florida, north to Maine, and west to Wisconsin, Illinois, and Missouri. Also in Hawai’i. Description. English ivy has two growth forms. In the juvenile stage, it is an evergreen, perennial vine growing as long as 100 ft. (30 m), or as tall as the structures or trees on which it climbs. When mature and able to produce flowers and fruit, after about 10 years, English ivy becomes a woody shrub. Without something to climb on, the young stems form a trailing ground cover, rooting at leaf nodes. Leaf shape is variable, depending on the age of the plant, with the three-lobed form being most commonly recognized. The simple, alternate leaves are a deep, glossy green, with a waxy or almost leathery cuticle. They exude an odor when crushed. Leaves on young vines are palmately three- to five-lobed and heart-shaped, 1.5–4 in. (4–10 cm) long and similar in width. The terminal lobe is the largest, while the two at the base are smaller or even absent. Climbing stems have more lobes and lightercolored veins. Plants become adults when they reach the reproductive phase. They grow a woody, erect stem from either the ground or from a climbing vine and become a shrub. Leaves on shrubby stems are a lighter green, oval, and not lobed. Young shoots and leaves are hairy and scaly, but leaves of older plants are glabrous. In both stages, the petioles are as long as the leaf. Plants grow fastest in the vine stage and more slowly in the shrub stage.

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Roots in the soil are shallow and not extensive. Adventitious rootlets at leaf nodes enable the plant to climb vertical surfaces, such as walls and tree trunks. However, the rootlets do not damage the host. They exude a glue-like substance that allows them to adhere to, but not penetrate, surfaces. English ivy vines grow up buildings, other structures, and trees, but do not strangle trees and are not parasitic. Plants will flower and set seed if they receive enough light. Bloom time is autumn. Flowers emerge in umbel clusters, either solitary or on racemes, on the ends of branches that extend at right angles from the climbing vines. Flowers are radial, 0.2–0.3 in. (5–7 mm), with five white or yellowishgreen petals. Fruit is a berrylike drupe, dark red or purple to black, 0.25–0.35 in. (6– 9 mm). Each contains 1–5 hard, stone-like seeds. If not eaten by birds, fruit may remain on the vine throughout the winter. Because it is evergreen, English With the exception of wet areas, English ivy thrives in most ivy grows year-round, although environments, including open forests and meadows. It is absent from more slowly during the cooler most of the mountain and northern Great Plains states. (Native range approximated from USDA GRIN and selected references. Introduced winter months. Related or Similar Species. range adapted from USDA PLANTS Database, Invasive Plant Atlas of the United States, and selected references.) English ivy has hundreds of horticultural varieties. Native climbers that may appear similar include wild grape and Dutchman’s pipe vine. Wild grape plants are woody vines with climbing tendrils and large three-lobed leaves with toothed margins. Dutchman’s pipe is a deciduous woody vine that has heart-shaped leaves with smooth margins. Nonnative, sometimes invasive, species may appear similar to English ivy. Plants of the cinnamon vine, also called Chinese yam, climb by twining, and its leaves are opposite and arrow-shaped. Porcelainberry (see Vines, Porcelainberry) is a woody, deciduous vine that climbs with tendrils. Although its leaves are alternate and deeply lobed, they are usually toothed, resembling leaves of wild grape. Boston ivy also resembles English Ivy, but it is a deciduous vine. Atlantic ivy, also called Irish ivy, has leaves as large as 4 in. (10 cm) wide,

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A. English ivy can cover and replace all other vegetation. (David J. Moorhead, University of Georgia, Bugwood.org.) B. Roots at leaf nodes enable the plant to climb. (Chuck Bargeron, University of Georgia, Bugwood.org.) C. Vines can smother the host tree. (James H. Miller, USDA Forest Service, Bugwood.org.) D. When they become a shrub, plants are mature and able to produce flowers. (Jan Samanek, State Phytosanitary Administration, Bugwood.org.) E. Fruit are small, berrylike drupes. (Forest and Kim Starr, U.S. Geological Survey, Bugwood.org.)

covered with yellowish-brown or rusty-brown hairs. Leaves of colchis ivy, also called Persian ivy, may be wider than 4 in. (10 cm). They are dull green on the upper surface and have scale-like hairs. Poison ivy has some similar characteristics with English ivy, but it is deciduous, has compound leaves with three leaflets, and whitish berry clusters. Distinguishing characteristics of English ivy are that the evergreen leaves are palmate and dark green with a waxy cuticle. Introduction History. English ivy was probably introduced into North America as an ornamental in early colonial times. It was, and remains, a popular ornamental because it is a dependable, evergreen groundcover requiring little maintenance. It is very cold hardy and pest free, and is still widely sold in plant nurseries. It was also used for erosion control because of its propensity to root at leaf nodes, although its shallow root system renders it ineffective. It kills other ground-growing plants, leaving a bare soil surface that offers little resistance to water flow. Habitat. Widespread in woods and rocky locations in its native range, English ivy grows from sea level to 3,300 ft. (1,000 m). In North America, it invades open forests and forest edges, fields, hedgerows, and the margins of coastal salt marshes, often after some type of natural or human-induced disturbance. It prefers moist deciduous forest, but can grow almost anywhere, in a variety of exposures, moisture regimes, and slopes. Although it is tolerant of various conditions, it does not grow where the water table is high or in wet areas. It grows in both alkaline and acid soils but prefers slight acidity, a pH of 6.5. Although it is tolerant of shade, where it will grow and spread, it grows more vigorously and will flower in full sunlight. Reproduction and Dispersal. English ivy reproduction is primarily vegetative, but it also produces abundant seeds. Plants produce many adventitious roots, from each leaf node, and any stem fragment in contact with soil will sprout. Flowers are pollinated by flies and bees in the fall, when few other plants are flowering. Birds eat and disperse the seeds, of which approximately 70 percent are viable. The seeds have a hard coat that must be scarified, usually in the bird’s digestive tract. However, the toxic glycosides in the seeds often cause the birds to vomit the seeds.

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Impacts. English ivy is a serious problem in some areas on the West Coast and in woodlands on the East Coast, especially from Virginia to New York. It is very common near urban areas. By covering plants and trees, it alters or halts normal succession and threatens all layers in forests and in open areas, both ground plants and canopy. It inhibits generation of understory native plants by shading the soil and preventing herbs and seedlings from growing, with the result that the forest ecosystem cannot maintain itself. When English ivy grows up tree trunks, especially in deciduous forests where more light is available for winter growth, it shades out the tree canopy, killing the tree within a few years. In addition, the weight of the vines can increase storm damage during periods of high wind, rain, snow, or ice. Trees heavy with English ivy also may pose a hazard to people or structures. Wildlife is affected by the altered ecosystem, and the leaf litter changes the nutrient content of the soil. Toxic compounds, glycosides, in the berries and leaves cause vomiting, diarrhea, nervous disorders, and dermatitis in sensitive individuals. Some symptoms are more serious, including breathing difficulty, coma, fever, muscular weakness, and lack of coordination. English ivy is host for a pathogen, bacterial leaf scorch (Xylalla fastidiosa), which affects native and ornamental trees, such as elms, oaks, and maples. Management. Most research regarding English ivy has been in the development of cultivars, not in its control as an invasive species. The best control advice is to not plant it. Pruning and hand-pulling up vines is an effective physical control method, especially for small populations. Workers should take precautions to protect themselves from the plant’s potentially toxic effects. Hand-pulling or cutting can be effective in areas where herbicide use is impractical or impossible. The entire plant, including roots and runners, must be removed. It is especially important to remove the vines from trees because the flowers and seeds grow on the upright parts of the vine. Because stem fragments can sprout if they contact soil, cut portions should be bagged and properly disposed of. After the base of the plant is cut, the vines in the tree may remain a couple of years, but will eventually die. To exhaust nutrient supplies in the roots, new sprouts should be cut as they appear. Any method attempted should minimize disturbance to the soil, and native plants should be reintroduced to prevent re-infestation of English ivy. Selectively burning plants with a blow torch may eventually use up the plant’s reserves. The potential effects of grazing are unknown. Covering ground infestations with several inches of wood chips, grass clippings, or hay may be effective. Mulch coverings should be applied for at least two growing seasons, replenishing as needed. Because English ivy is tolerant of preemergent herbicides, and the waxy cuticle on the leaves makes it resistant to postemergent herbicides as well, chemical control is not always effective. Glyphosate may be useful on young plants, and triclopyr may be effective when most of the top growth of leaves is removed. Cutting the stems prior to herbicide application facilitates chemical control. Glyphosate or triclopyr can be applied to cut stumps or cut vines. Systemic foliar sprays are best applied on the evergreen ivy when the deciduous plants

Old Plants

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nglish ivy is noted for having a long life. Some vines are 1 ft. (0.3 m) in diameter, and the oldest reported plant is 433 years old.

606 n VINES are dormant, any time temperatures are above 55–60ºF (13–16°C), but before spring herbs and wildflowers emerge. Winter treatments are less effective because the plant is growing more slowly. No biological controls are known, and attempts are unlikely because English ivy is an important landscape plant in many parts of the United States.

Selected References “English Ivy.” Southeast Exotic Pest Plant Council (SEEPPC) Invasive Plant Manual, 2003. http:// www.se-eppc.org/manual/HEHE.html. “English Ivy Hedera helix.” Weed of the Week. U.S. Department of Agriculture, Forest Service, Invasive Plants, 2006. http://www.na.fs.fed.us/fhp/invasive_plants. Swearingen, Jil M., and Sandra Diedrich. “Hedera helix.” Weeds Gone Wild: Plant Conservation Alliance’s Alien Plant Working Group, 2009. http://www.nps.gov/plants/alien/fact/pdf/hehe1.pdf.

n Field Bindweed Also known as: Creeping Jenny, European bindweed, small-flowered morning glory, creeping Charlie, field morning glory, devil’s guts vine, corn bind, and others Scientific name: Convolvulus arvensis Synonyms: Convolvulus ambigens, C. incanus, Strophocaulos arvensis Family: Morning Glory (Convolvulaceae) Native Range. With the exception of the far northern latitudes, Europe, Asia, and northern Africa. Distribution in the United States. All states except Alaska. Description. Field bindweed is an herbaceous perennial vine with slender stems that sprawl on the ground or twine around objects. The branching stems, 1–6.5 ft. (0.3–2 m) long, are normally glabrous but may be pubescent. The stem surface appears ridged or corrugated. Prostrate plants can form tangled mats on the ground 2 in. (5 cm) thick. Leaves, 0.4–4 in. (1–10 cm) long and 0.1–2.4 in. (0.25–6 cm) wide, are alternate. They are usually arrowhead in shape, with the lobes at the base pointing outward, often at right angles from the leaf. Leaves are variable, however, and sometimes are almost oval. The leaves, which are sometimes sparsely hairy, are supported by glabrous or pubescent petioles approximately 1.2 in. (3 cm) long. Vines are deciduous, dying back to the root crown in winter. The fleshy, pale root system includes a perennial taproot, which may extend 2–10 ft. (0.6–3 m) deep. Many creeping lateral roots, 2–10 ft. (0.6–3 m) long, grow from buds on the taproot. Occurring in the top 2 ft. (0.6 m) of soil, rhizomes associated with the lateral roots can create independent plants. One plant may have a root system 20 ft. (6 m) in diameter and 30 ft. (9 m) deep. From May to September, small clusters of 1–3 flowers grow on a 2.5 in. (6 cm) long peduncle extending from the leaf axis. The peduncle has a pair of small linear bracts about midway down. The funnel- or trumpet-shaped flowers, which open only in the morning, are white, pink, tinged with pink, or rarely, red. The flowers are small, 0.5–1 in. (1.5– 2.5 cm) both long and wide. Both the five petals and the five green sepals are fused. The sepals are glabrous, but the petals may be slightly pubescent. Flowering is indeterminate, meaning that flowers will continue to develop as the stems grow until killed by frost.

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Fruit, which matures from June to September, is a glabrous cone-shaped capsule, 0.25 in. (0.6 cm) long, with four parts and four dark-brown or black egg-shaped seeds. Related or Similar Species. Western morning glory, a perennial native to the western states, is also called chaparral false bindweed or bush morning glory. Although growing primarily in chaparral or pine forests on dry slopes in California, it can also be a weedy pest in agricultural fields. Its flowers are 1–1.5 in. (2.5– 4 cm) long. The basal lobes of the leaves are squared or slightly indented with two lobes. Hedge false bindweed, which is also known by several other names, is another invasive vine native to Europe. It can be distinguished by larger vegetative parts. Leaves are 2–4.5 in. (5–12 cm) long. Flowers, 1.5– 3 in. (4–7 cm) long, are solitary, not in clusters, and the pedicels are 2–6 in. (5–15 cm) long, and leaves are 2–4.5 in. (5–12 cm) Present in every state except Alaska, field bindweed has been considered a weed in the United States since 1875. (Native range approximated from long. Mallow bindweed or holly- USDA GRIN and selected references. Introduced range adapted from hock bindweed, from the Med- USDA PLANTS Database, Invasive Plant Atlas of the United States, and iterranean region of Europe, selected references.) has become naturalized in the foothills of some California mountains and in the southwestern states. It is a showy perennial with purple to deep-pink flowers. Some of the upper leaves are distinguished by having deeply divided lobes. Field bindweed is difficult to distinguish from Ipomoea species, which are also referred to as morning glories. The styles are different, and the sepals of Ipomoea may not be fused. Dioscorea species, in the yam family, are also twining vines with heart-shaped leaves. Because they are monocots, the leaves have parallel veins with no secondary vein network and the flowers have three parts. Chinese yam, also called air potato, is an invasive vine. It can be distinguished by the leaf venation, inconspicuous flowers, and the bulbils, or tubers, which hang from the vine.

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A. Stems of field bindweed sprawl on the ground. (Richard Old, XID Services, Inc., Bugwood.org.) B. Leaves are supported by long petioles; flowers are on long peduncles. (Steve Dewey, Utah State University, Bugwood.org.) C. Flowers are funnel-shaped, with fused petals. (Joseph M. DiTomaso, University of California-Davis, Bugwood.org.) D. Leaf form is variable, but usually arrow-shaped. (Ohio State Weed Lab Archive, The Ohio State University, Bugwood.org.) E. Plants often clog machinery. (John D. Byrd, Mississippi State University, Bugwood.org.)

Introduction History. Field bindweed was introduced to the United States in the 1730s for use in medicine and as an ornamental. It was considered a weed in European gardens as early as 1633 and was recognized as a weed in North America in 1875. Habitat. Field bindweed grows in a wide range of climates, including temperate, Mediterranean, and tropical regions. It is most abundant in slightly disturbed sites, such as rangeland, pastures, abandoned fields, roadsides and railroad right-of-ways, and waste places, but it is also found in cultivated fields, orchards, vineyards, and gardens. It is common along irrigation drip lines in vineyards and along fencerows. Field bindweed grows best on moist, fertile soils, but not in wet sites or standing water. It may also be found on poor, dry, gravelly soils. It grows best in open, sunny locations but can invade forests if the canopy is not too dense. Reproduction and Dispersal. Field bindweed reproduces both by seed and vegetatively. Seed production is variable. More seeds are produced under dry, sunny conditions from plants growing on calcareous soils. Rain and heavy wet soils reduce seed output. Plants usually do not flower and set seed until their second season. One plant can produce as many as 500 seeds. Field bindweed is not self-compatible and must be pollinated by honey bees, bumblebees, butterflies, and moths. Seed pods are dehiscent. Most seeds fall near the parent plant, but some are dispersed over a long distance by water, birds and other animals, and agricultural activity. Seeds or root pieces may be contaminants in soil, mulch, crop seed, or hay, and may be also transported by farming equipment. The hard-coated seeds can survive as long as six days in the digestive tract of birds and animals. Although some seeds are able to germinate just 10–15 days after the flower is pollinated, 80 percent develop an impermeable coat that requires scarification. Seeds remain viable for 20–50 years, and the seed bank is extensive. If moisture is available, germination may take place throughout the growing season, but the peak occurs in mid-spring to early summer. A cold period of six weeks in winter, with temperatures dropping to approximately 41ºF (5ºC), aids germination. Light is not required. Most new shoots from rhizomes emerge in early spring. Root pieces as small as 2 in. (5 cm) can produce new growth. Patches of field bindweed can expand their radius as much

FIELD BINDWEED n 609

as 33 ft. (10 m) in one season. Although rhizomes can survive low winter temperatures, they will die if the ground freezes. Impacts. Growing in large patches and difficult to control, field bindweed is one of the worst weeds in agricultural fields. It is especially a problem in cereal, bean, and potato crops. It can reduce the harvest of cereal grains by 30–40 percent or more and outcompete vegetable seedlings. The plant competes with crops for nutrients and soil moisture and can increase irrigation costs. Although the taproot accesses deep soil moisture, enabling the plant to withstand drought, plants may also become dormant in summer, resprouting with fall rains. Its tangled vines can interfere with crop harvesting. Field bindweed can be an alternate host for viruses that affect crops, such as potato x disease, tomato spotted wilt, and vaccinium false bottom. Alkaloids in the foliage are mildly toxic to grazing animals and may cause intestinal problems in horses. In natural areas, the weight of the vines can break or uproot native species. By outcompeting native plants for sun, moisture, and nutrients, bindweed crowds out grasses and forbs, decreasing biodiversity in the habitat. Management. Control and prevention vary according to site, whether it is natural or agricultural. Maintenance of a good vegetative cover can prevent infestations. Once established, field bindweed is extremely difficult to eradicate. Physical control, including tilling, plowing, or disking, must be carefully planned to avoid eliminating competitors, which would encourage more root sprouts from field bindweed. To prevent spreading seeds or rhizome pieces in fields of actively growing crops, avoid tilling the field around the bindweed infestation. A year of deep cultivation, followed by planting a competitive crop such as winter wheat or alfalfa, may control bindweed in agricultural fields. The field should be cultivated before plants flower and repeated each time new shoots appear. Tilling every two weeks should deplete root reserves, but may also increase the potential for soil erosion. If done within three weeks of emergence, cultivation to a depth of at least 4 in. (10 cm) will destroy new seedlings. Small plants or new infestations, including all roots, can be pulled out by hand. Because field bindweed does not tolerate water-logged soils, flooding the area, 6–10 in. (15–25 cm) deep, for 60–90 days will kill plants. Although sheep and cattle avoid using it as forage, it can be fed to livestock as fodder. Hogs and chickens will eat the stems, leaves, and exposed roots or rhizomes. Mowing will reduce the seed crop. Shading plants by covering with paper, straw, wood chips, or black plastic may kill them. In orchards or vineyards, a cover crop of ryegrass, hairy vetch, and red clover will shade plants and can reduce the density and biomass of bindweed. Chemical applications repeated over several years may not eliminate field bindweed but may suppress it enough to minimize the problem. Different biotypes have varying resistance to herbicides. Glyphosate or 2,4-D, which should be applied before seed sets, is less likely to damage crops. Although herbicides are difficult to use in infested fields of broadleaf crops, a broadleaf selective herbicide can be used in grain crops. Spot treatment may prevent plants from spreading. Herbicides are less effective when plants are drought-stressed, and fall applications may be more effective than those applied in spring. Two biological control agents have been released. A bindweed gall mite (Aceria malherbae), native to Europe and North Africa, causes galls to form on the leaves, distorting growth and reducing seed production. Stems with galls can be picked and taken to other infested sites to disperse the mites. The gall mite also attacks hedge bindweed and some native Calystegia species of morning glory. A bindweed defoliating moth (Tyta luctuosa), native to Europe, North Africa, and Eurasia, feeds on flowers and leaves. The insect was not yet established in 2005, and the extent of damage is not known.

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Uses for Bindweed

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indweed has been considered a medicinal plant in Europe and Arabic-speaking countries for centuries. It is used to stop bleeding and heal wounds, to reduce fever, and to induce vomiting. Native Americans adopted the plant as early as 1890, using it as a laxative. Individuals of the Navajo Nation may use it on spider bites and as an intestinal stimulant. The Pomo culture uses it to facilitate menstruation and childbirth.

Selected References Burnham, R. J. “Plant Diversity Website, Convolvulus arvensis.” CLIMBERS Website, 2010. http://www -personal.umich.edu/~rburnham/SpeciesAccountspdfs/ConvarveCONVFINAL.pdf. “Convolvulus arvensis, Field Bindweed.” Texas Invasives, 2008. http://www.texasinvasives.org/plant _database/detail.php?symbol=COAR4. “Dioscorea oppositifolia, Chinese Yam.” Texas Invasives, 2008. http://www.texasinvasives.org/plant _database/detail.php?symbol=DIOP. Jacobs, Jim. Ecology and management of field bindweed (Convolvulus arvensis L.). Invasive Species Technical Note No. MT-9. U.S. Department of Agriculture, Natural Resources Conservation Service, 2007. http://www.msuextension.org/ruralliving/Dream/PDF/Weed/bindweed.pdf.

n Japanese Dodder Also known as: Giant Asian dodder, Tu Si Zi, devil’s hair, devil’s gut, strangleweed Scientific name: Cuscuta japonica Synonyms: Monogynella japonica Family: Morning Glory (Convulvulaceae) or Dodder (Cuscutaceae) Native Range. Temperate eastern Asia, including Mongolia, China, Manchuria, Korea, Japan, Ryukyu Islands, Taiwan, and tropical Vietnam. Distribution in the United States. Southeastern states, Texas, Florida, and South Carolina. Recently found in 2004 in northern California. The northernmost plant, in Redding, California, died naturally over the winter. Description. Japanese dodder is an annual holoparasitic vine, meaning that it can only obtain food and water from a host plant and will die without one. Usually an annual, it may overwinter on host plants from tissue embedded in the host. In warm climates, the plant may grow year-round. The much-branched stems are round, somewhat fleshy, and smooth. Although the vine appears leafless, the stem is lined with tiny scale-like leaves. The stems lack chlorophyll and range in color from pale green to vibrant yellow-green or gold, sometimes with red spots or striations. Stems are thick, similar in size to and resembling intertwining strands of cooked spaghetti. The plant coils around and attaches to its host with peg-like modified roots called haustoria, which dissolve and penetrate the bark. The haustoria extract everything needed for life from the host plant. The tangled mass of stems can blanket the host plant and drape down to the ground. The plant produces many inconspicuous pale-yellow flowers, supported by short stalks, in leaf axils. The fruit is a two-cell capsule containing four seeds. Seeds are tiny, less than 0.1 in. (3 mm) long, pale straw to black in color, and irregularly dented.

JAPANESE DODDER n 611

Related or Similar Species. The term dodder is used to refer to more than 150 parasitic, yellow twining plants that appear to be nothing but leafless stems. Stems of the many native dodder plants, which are present in all states except Alaska, are thin, resembling string or thread. Native dodders usually parasitize herbaceous plants and small shrubs, enveloping them in a large, spreading web, and can be pests in orchards, field crops, and gardens. Common dodder, also called scaldweed or swamp dodder, usually grows in low, damp locations. The stem is yellow to dull orange, and the tiny bellshaped flowers are white. Alfalfa dodder, a bright yellow species native to Africa and Eurasia, can be a problem in alfalfa fields and vegetable crops. Introduction History. Japanese dodder was accidentally introduced three times, on kudzu plants, to San Antonio, Texas, Quincy, Florida, and the Clemson University cam- The horticultural and agricultural industries of the United States may be pus, South Carolina. It was seriously harmed if Japanese dodder spreads from its presently localized believed to have been eradi- sites. (Native range adapted from USDA GRIN and selected references. cated in all three locations. In Introduced range adapted from USDA PLANTS Database, Invasive Plant 2001, the parasitic vine was Atlas of the United States, and selected references.) newly discovered in several locations in Houston, Texas, and in 2004 in Redding, California. By 2010, Japanese dodder was recorded at more than 245 sites in California, and more are expected. Dodder seeds are a common contaminant of commercial seed, spice, baggage, and straw. Any shipment found to contain whole dodder seeds of any species is denied entry into the United States. The shipment is either returned to the country of origin or the seed is sterilized. Heat-treated, sterile seeds may be legally imported, but seeds declared to be sterile are often not and will sprout. In spite of such precautions, seeds are also intentionally imported and distributed as a medicinal herb, probably by Asian immigrants or visitors. Because crushed or ground seeds are not viable, they are not a threat. Habitat. Japanese dodder will attach itself to both herbaceous and woody host plants. In Japan, the plant is known to parasitize 7 types of crops and 32 different species of wild

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A. Vines completely cover this privet bush and drape to the ground. (Kim Camilli, Texas Forest Service, Bugwood.org.) B. Vines look like a tangled mass of cooked spaghetti. (© Barry Rice, sarracenia.com.) C. Haustoria from the white stem are beginning to penetrate the bark of this lemon tree. (W. Thomas Lanini, University of California-Davis.) D. Stems climb by twining around the host plant. (© Barry Rice, sarracenia.com.) E. Infected plants must be completely removed, as in this street scene in Houston, Texas. (Kim Camilli, Texas Forest Service, Bugwood.org.)

plants in several families and genera. Japanese dodder has been seen on 20 species of plants in south Texas, both herbaceous and woody, including ornamental crape myrtles, native live oaks, and introduced privets. Crops in the United States that may be affected include orchard trees, eggplant, potatoes, onions, pumpkins, tobacco, and soybeans, as well as others. It is also commonly found on two introduced plants, kudzu (see Vines, Kudzu), and purple osier willow. It can invade natural areas as well as roadsides and unimproved property. In California, Japanese dodder may be found as ornamentals in residential areas, particularly in Southeast Asian neighborhoods, where it is used for medicinal purposes. It may also grow in riparian areas, where it affects important native plants such as willows, California live oak, and California buckeye. Loss of nesting sites may affect Least Bell’s Vireo and other endangered birds. Japanese dodder does not grow in hot, dry deserts, or at high elevations. Because the plant grows in several temperate climates in Asia, the potential is high for it to extend its range to similar climates in North America. Reproduction and Dispersal. Dodder seeds are carried over long distances as a contaminant in crop seed, and more locally by moving water, machinery, and soil disturbances such as erosion. Although most germinate within a year, seeds remain viable for 10–20 years. Plants in South Carolina produce viable seeds, but none have been seen in California or Texas. Seeds may germinate either in soil or on the bark of the host plant, and seedlings are both rootless and leafless. Although they may survive several weeks, using the soil as an anchor, seedlings will die unless they find a host. As the seedling stem grows longer, its tip twines toward other plants and seems to “sense” a potential host. Stems can grow several inches a day. Stem pieces are distributed locally by water, birds, animals, and human garden activities, such as pruning, composting, and improper disposal. Impacts. Because it is a parasite that takes nutrients and water from the host plant, Japanese dodder negatively affects growth and the yield of infested plants. It can kill a large plant in 2–3 years. It is capable of completely destroying a crop, and is a serious threat to agricultural and horticultural industries. The loss of native plants in riparian areas alters food chains, eliminates shade and nesting habitats, and may contribute to erosion.

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Although tall trees may be resistant to the effects of Japanese dodder, the understory is more susceptible. Potential impacts of more widespread infestations of Japanese dodder are serious. The export market for ornamentals and crop seeds may be threatened. Other countries may deny entry of seed exported from the United States, especially crop seed, if it may be contaminated with dodder. Ornamental plants grown for export would have to be more closely inspected. Maintenance costs of both private landscapes and public parks would increase as infested plants are removed and replaced. The agriculture industry would also bear the expense and loss in removing infected fruit and nut trees in orchards. Japanese dodder is a host for several serious citrus viruses that may be transmitted to orchard crops. Management. Physical control can be accomplished in small infestations by cutting the infected host plant to the roots, then bagging all host and dodder fragments and disposing of them in a deep commercial landfill. If possible, remove plants within 10 ft. (3 m) of the infected plant. Because of the risk of re-infestation, neither host nor dodder should be composted. Widespread infestations in fields can be eliminated with frequent tilling, burning, or herbicide applications. Burning will destroy not only the dodder and its seeds, but also the host plant. Host plants must be removed because haustoria embedded in the plant will sprout. Chemical applications are effective. Preemergent herbicides will prevent germination of seeds and kill seedlings that have no host. Postemergents will kill both the dodder and host, allowing all plant debris to be removed without threat of fragments resprouting. Sites can be treated with both a soil fumigant and a preemergent. Systemics may be injected into large trees. No biological controls are known.

Selected References Camilli, Kim. “Giant Asian Dodder: A New Invasive Plant Detected in Texas.” Invasive Plants of the Eastern United States. U.S. Department of Agriculture, Forest Health Technology Enterprise Team. Morgantown, WV, 2003. http://dnr.state.il.us/stewardship/cd/other/texas.html. “Japanese Dodder (Cuscuta japonica).” Plant Division, Noxious Weed Control. Oregon Department of Agriculture, n.d. http://www.oregon.gov/ODA/PLANT/WEEDS/profile_japanese dodder.shtml.

Medicinal Uses for Japanese Dodder

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eeds and other plant parts of Cuscuta have been used for centuries by Chinese herbalists for various ailments, including jaundice, kidney and digestive problems, gallbladder disorders, and sore eyes. The plant is used as a male aphrodisiac and is a major ingredient in currently sold herbal products for male enhancement. Cuscuta is still used by contemporary Chinese herbalists for treating such wideranging conditions as sperm leakage, dry eyes or blurred vision, lower back pain, frequent urination, and ringing in the ears. Products are widely available in health food stores and on the Internet.

614 n VINES Markmann, C., and R. Marushia. “Summary of Dodder (Cuscuta japonica) Biology, Concerns, and Management.” Plant Pest and Health Prevention Services (PHHPS). California Department of Food and Agriculture, 2006. http://www.cdfa.ca.gov/phpps/ipc/noxweedinfo/pdfs/jdodder _summary.pdf. Miller, Arthur. “Japanese Dodder.” Invasive Plants of the Eastern United States. U.S. Department of Agriculture, Forest Health Technology Enterprise Team, Morgantown, WV, 2003. http://dnr.state .il.us/stewardship/cd/other/jdodder.html.

n Japanese Honeysuckle Also known as: woodbine, Chinese honeysuckle Scientific name: Lonicera japonica Synonyms: Nintooa japonica Family: Honeysuckle (Caprifoliaceae) Native Range. Eastern China, Korea, and Japan. Distribution in the United States. Most of the United States except for the northern Great Plains. Scattered in California and on the Hawaiian Islands. Description. Japanese honeysuckle is a perennial woody vine or shrub with a trailing or twining habit. By twisting or coiling its stems around limbs and trunks of small trees, which are typically less than 6 in. (15 cm) in diameter, it can climb vertical structures. Encircling the tree trunk in closely spaced spirals gives the vine support for itself after the host tree has died. Vines, usually 6.5–10 ft. (2–3 m) long, can be 80 ft. (24 m). Pubescence is variable, but reddish-brown to light-brown young stems are often finely hairy. Older stems are glabrous and hollow, with brownish bark peeling in long strips. In the southern and MidAtlantic states, Japanese honeysuckle remains evergreen. In the colder North, it is semievergreen, dropping its leaves after a long cold spell. Leaves, 1.5–3 in. (4–8 cm), are opposite on the stem and have short petioles. Leaf shape is variable, oblong to oval. Leaves on new spring shoots may be pinnately lobed. Leaf petioles and the midribs on both sides of the leaves may also be finely hairy. Roots are vigorous and widespread in the soil. One root system was recorded at almost 10 ft. (3 m) across and 3.3 ft. (1 m) deep. Bloom time varies with location; April through December in the South, but only June in Michigan. The very fragrant flowers grow in the leaf axils, usually in pairs but occasionally singly. They are tubular, with five fused white petals, tinged with pink or purple, but they turn yellowish as they age. Corollas are distinctly bilabiate. Fruit, inconspicuous small round berries, 0.25 in. (6 mm), that become glossy black when ripe, develop on 1.2 in. (3 cm) stalks in the fall. Each berry contains 2–3 oval seeds. Related or Similar Species. Two cultivars are also invasive. Hall’s honeysuckle is more aggressive and has pure white flowers. Chinese honeysuckle is less common, with purple, glabrous leaves and red flowers. Several Eurasian bush honeysuckles (see Shrubs, Exotic Bush Honeysuckles), such as Amur honeysuckle, Morrow’s honeysuckle, Tartarian honeysuckle, and European fly honeysuckle, have also been introduced to North America for ornamental plantings, wildlife cover, and erosion control. They are generally deciduous shrubs ranging 6–15 ft. (1.8–4.5 m) tall and do not have climbing, coiling vines. Because they have variable tolerances, bush honeysuckles are found in habitats similar to those occupied by Japanese honeysuckle, especially on disturbed sites. Opposite leaves, 2–2.5 in. (5–6 cm) long, are oval or

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egg-shaped. Older stems of Japanese honeysuckle are usually hollow, compared with native honeysuckle stems that are solid. The native coral honeysuckle is distinguished from Japanese honeysuckle by several features. Flowers are red with yellow interiors, and berries are orange to red. Young leaves are glabrous, not hairy, and the uppermost leaves on the vine are not separate, but fused, forming one leaf through which the vine grows. Introduction History. Japanese honeysuckle was introduced to Long Island in 1806 as an ornamental because of its fragrant flowers and rapid growth. A second introduction occurred in 1862, also in New York. By 1919, the plant had naturalized from Massachusetts to the Gulf of Mexico and was described as an invasive problem. It continues to be sold in nurseries as an attractive landscape plant and is still planted along highways for erosion control and bank stabilization. Wildlife officials in some states have pro- Japanese honeysuckle, an attractive ornamental with fragrant flowers, is moted its use as winter forage still planted along highways for erosion control and is found in most states. (Native range adapted from USDA GRIN and selected references. for deer. Habitat. Japanese honey- Introduced range adapted from USDA PLANTS Database, Invasive Plant Atlas of the United States, and selected references.) suckle grows best in full sun with rich soil, but is tolerant of many conditions. It invades a variety of habitats, primarily where the natural ecosystem has been disturbed, including fields, forests, wetlands, floodplains, southern pine stands, and abandoned homesites. Thickets are often dense at forest margins, along roadsides, and in open woodlands, prairies, and old fields. Although it is rarely found in deep shade, it is somewhat shade tolerant and can invade mature forests, both dry and mesic, by first growing in forest openings or in partial shade. Japanese honeysuckle can go unnoticed in healthy forests until wind, disease, ice, landslide, or human activity causes an opening to develop, after which plants take advantage of better conditions and grow vigorously. Cold winters may limit its northward expansion, while drier conditions, which affect seedlings, may limit its western spread. Although the northern limit is currently where high

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A. Vines can overtop and completely enclose other plants. (Chris Evans, River to River CWMA, Bugwood.org.) B. Oblong leaves are opposite on the stem. (Karan A. Rawlins, University of Georgia, Bugwood.org.) C. Lower leaves on new spring growth may be pinnately lobed. (Ted Bodner, Southern Weed Science Society, Bugwood.org.) D. Tubular, bilabiate flowers grow in pairs from leaf axils. (Chuck Bargeron, University of Georgia, Bugwood.org.) E. Fruit are small berries. (Karan A. Rawlins, University of Georgia, Bugwood.org.) F. Bark on old stems is stringy and peeling. (James H. Miller, USDA Forest Service, Bugwood.org.)

temperatures in winter average −13ºF (−25ºC), Japanese honeysuckle continues to spread north due either to increased tolerance or to warmer winters. Plants on the northern edge are smaller due to the shorter growing season and rarely produce flowers or seeds. It grows most vigorously and is the biggest pest where annual precipitation is 40–47 in. (1,000– 1200 mm) and winter low temperatures average 5 to −17.5ºF (−8 to −15ºC). Reproduction and Dispersal. Although Japanese honeysuckle reproduces both vegetatively and sexually, its runners and rhizomes allow plants to overrun sites. New shoots grow from the roots, and vines will develop roots at nodes when in contact with moist soil. Stem cuttings will also root. Because the bloom season lasts several months, many fruits and seeds are produced. Fruit are eaten by deer, rabbits, turkey, and quail, but long-distance seed dispersal is primarily by birds, which deposit seeds in new locations. Little research has been conducted on seeds, but the number produced is related to soil chemistry. A large seed bank remains in the soil, ready to sprout when the site is disturbed. Dormancy and germination requirements are variable. Impacts. A pest in both managed forests and natural areas, Japanese honeysuckle spreads and outcompetes and replaces native plants in several ways. By branching frequently and rooting at nodes, the plant forms dense interlaced canopies, arbors, or thickets that can completely cover other vegetation. Forming a dense blanket over existing plants, it eliminates their light and prevents them from photosynthesizing. Shrubs and trees that provide support are either killed by girdling or break under the weight of the vines. The root system is vigorous, depriving native plants of necessary nutrients and rendering them less healthy. It is a rapid grower, and its evergreen to semi-evergreen nature gives it an advantage over deciduous species. Plants change forest structure by altering or stopping natural forest succession by eliminating the understory, either by shading or girdling. As an evergreen, Japanese honeysuckle casts shade in early spring, preventing the germination of ephemeral spring herbs. As

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understory herbs, shrubs, and young trees are covered and killed, gaps are created within the forest. With more light, Japanese honeysuckle grows even more vigorously, and the openings provide places for other invaders, such as kudzu and English ivy, to take hold. Changes in the understory of forests alters wildlife habitat and eliminates nesting sites for song birds. In contrast, dense thickets provide cover for other birds and small mammals, while leaves and seeds provide food for cottontail rabbits and birds. White-tailed deer eat the evergreen leaves, providing important winter forage. Japanese honeysuckle is a temporary host for agricultural pests, such as a spider mite (Tetranychus urticae) that attacks corn and peanuts, a cicadallid cotton pest (Empoasca biguttula), and the tobacco budworm. Management. Because of the difficulty of controlling Japanese honeysuckle, the goal should be 100 percent mortality. Infestations can be prevented if plants are removed as soon as they are noticed, preventing their spread. Plants, however, are hard to find when small. Regardless of what method is used to control Japanese honeysuckle invasions, sites should be monitored frequently for new growth. Methods should also minimize soil disturbance, which creates habitat for germination of not only Japanese honeysuckle, but other invasive species as well. Physical methods are generally ineffective in the long term because vines form roots at nodes and existing plants resprout from root buds. Cutting, pulling, or burning will weaken the plant but not kill it. Small stands or seedlings can be hand-pulled, but roots must also be removed. Although burning fails to kill the roots of mature vines, which will resprout, fires are more likely to kill seedlings and young plants. Mowing at least twice a year will keep vines and new shoots from spreading, but will not kill plants. Mowing, however, may also stimulate growth. Twining vines should be cut off of trees and shrubs, and all pieces must be properly disposed of because cut vines and branches will grow roots. Disking may be effective, but is very destructive and may also stimulate germination of the seed bank. Although goats will browse on Japanese honeysuckle, they would be invasive themselves if not confined. Chemical methods are the most effective means of control. Application is best done in the fall, when Japanese honeysuckle is still growing but native plants are going dormant. Large areas can be mowed to remove biomass, then treated with herbicides. Effective herbicides include glyphosate, 2,4-D + picloram, tebuthiuron, dicamba, and sulfometuron. A combination of burning in fall and winter followed by spraying new sprouts with herbicide is effective. Japanese honeysuckle has few natural enemies in North America. Although biological efforts are necessary for regional control, little research has been done. It is susceptible to honeysuckle latent virus and to tobacco leaf curl (Begomovirus).

How Fast Does Japanese Honeysuckle Grow?

A

growth rate of about 5 ft. (1.5 m) per year is typical, but in one location, it took vines only one year to cover a 14.75 ft. (4.5 m) tree. Each vine has many runners or canes, which also branch. The combined length from one sprout for one year’s growth can be more than 49 ft. (15 m). Source: Nuzzo, 1997.

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Selected References Bravo, Melissa A. “Japanese Honeysuckle.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2009. http://www.nps.gov/plants/alien/ fact/pdf/loja1.pdf. Nuzzo, Victoria. “Element Stewardship Abstract, Lonicera japonica.” Global Invasive Species Team, Nature Conservancy, 1997; updated 2009. http://wiki.bugwood.org/Lonicera_japonica. Swearingen, J., K. Reshetiloff, B. Slattery, and S. Zwicker. “Exotic Bush Honeysuckles.” Plant Invaders of Mid-Atlantic Natural Areas. National Park Service and U.S. Fish and Wildlife Service, 2002; updated 2003. http://www.invasive.org/eastern/midatlantic/loni.html.

n Japanese Hops Also known as: Japanese Hop Scientific name: Humulus japonicus Synonyms: Humulus scandens Family: Hemp (Cannabidaceae) Native Range. Temperate Asia, including southern and eastern China, Manchuria, the Amur region of Siberia, Korea, Japan, and the Ryukyu Islands. Also in tropical Vietnam. Distribution in the United States. Scattered in the eastern United States, from North Dakota east to Maine, south to Georgia, and west to Kansas. Currently most common in the northeastern United States, Japanese hops continues to expand its range. Description. Japanese hops is usually an annual vine, but it can be weakly perennial in warmer climates. The plant has no tendrils and climbs structures and other plants by twining its stems around the host. Without something on which to climb, plants can be trailing or prostrate. Stems, occasionally branching, may be 8–35 ft. (2.5–10.5 m) long by late summer. Stems are fairly stout, light green to reddish purple, and longitudinally ridged. Short, sharp, downward pointing prickles, which help the plant grasp host plants, line the stem ridges. The opposite leaves, both 2–6 in. (5–15 cm) long and wide, are palmate, usually with five deep lobes that taper to a point. Leaves on the top parts of the vine often have 3–5 lobes, while others may have 7–9 lobes. Leaf margins are coarsely toothed, with the serrations pointing forward. The upper leaf surface has a sparse cover of short, rough hairs, while stiff prickly hairs line the major vines on the underside. The stout, light-green leaf petioles, also covered with prickly hairs, are as long as or longer than the leaves, with a pair of small bracts, curved slightly downward, where the petiole joins the stem. Plants are dioecious, with male and female flowers on different plants, and bloom in July and August. Both types of inflorescences grow in leaf axils. Male inflorescences are erect spreading panicles, 6–10 in. (15–25 cm) long and as wide as 5 in. (12.5 cm). The panicle branches are slightly hairy and light green to pale red, with a pair of small bracts at the base. The yellow-green male flowers are very small, approximately 0.1 in. (3 mm), with five spreading light-green to pale-red sepals and no petals. Male flowers droop downward from the panicle branches. The female plant inflorescence is a short, catkin-like drooping spike of flowers and bracts, 0.25–1.5 in. (0.5–4 cm) in diameter, which becomes globular with age. A pair of small, inconspicuous female flowers, which have no petals, occurs at the base of each of the bracts. The cluster of pale-green, overlapping bracts, densely hairy at the margins, somewhat resembles a small pine cone. Initially, the bracts are narrow triangles, but they become broader as they age, with pointed, slightly recurved tips. The female flower inflorescence is called the hops. Seeds, one from each female flower, mature in September.

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The yellowish-brown achenes, with dark specks, are small, approximately 0.1–0.2 in. (3–5 mm), slightly oval and flattened, with a blunt tip. Related or Similar Species. The only other species in the genus is common hops, which is used in beer making. Common hops has five varieties, three of which are native to the United States, one native to Europe and West Asia, and one native to East Asia. Common hops leaves usually have three lobes or none, with rounded tips. The petiole is shorter than the length of the leaf. The male inflorescence is pale yellow, lacking the reddish tint of the sepals and branches of Japanese hops. The female flower spikes are oval and hairless, and the bracts, or scales, are blunt, either straight or curving slightly inward. Japanese hops does not contain the elements in common hops that are essential for brewing beer. Two native cucumber species may be confused with Japanese hops. The palmately veined leaves of the native bur Growing best in sunny habitats, Japanese hops frequently invades cucumber are alternate, with disturbed areas, such as roadsides and construction sites, in the eastern 3–5 very shallow lobes that are half of the United States. (Native range adapted from USDA GRIN and pointed at the tips. Although it selected references. Introduced range adapted from USDA PLANTS Database, Invasive Plant Atlas of the United States, and selected references.) is pubescent on the stem and underside of leaves, the plant has no prickles. It uses tendrils to climb. The monoecious plants have showy flowers, 0.5 in. (1.3 cm) in diameter, with white petals fused at the base. Fruits occur in clusters and are covered with white prickles which are approximately 0.5 in. (1.0–1.5) cm long. Wild cucumber has alternate, glabrous leaves and hairless stems. The thin leaves, with five deep, pointed lobes, have smooth margins. Wild cucumber also climbs with tendrils. The showy white flowers, 0.5–0.75 in. (1.3–2 cm) in diameter, each have six narrow, loose white petals. The fruit, occurring individually, resembles a small cucumber, about 2 in. (5 cm) long. Native Virginia creeper has compound leaves with five leaflets and no prickles. Introduction History. Japanese hops was introduced into the United States in the late 1800s for ornamental purposes and for use as a tonic in Asian medicine. It is an attractive

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A. Climbing plants form thick masses of vines. (Leslie J. Mehrhoff, Ecology and Evolutionary Biology, University of Connecticut, Bugwood.org). B. Leaves are palmately lobed. (Chris Evans, River to River CWMA, Bugwood.org). C. Female flowers are the “hops.” (Leslie J. Mehrhoff, Ecology and Evolutionary Biology, University of Connecticut, Bugwood.org.) D. Downward pointing prickles help the plant grasp its host. (Chris Evans, River to River CWMA, Bugwood.org.)

annual in gardens, especially the variegated forms, and is useful for garden screens. It is still sold in nurseries. Habitat. Although capable of growing in part shade, Japanese hops prefers bright sunlight. It is tolerant of any type of soil, including, sandy, loamy, clay, acid, neutral, or basic, as long as it is moist. Plants are most common in riparian and floodplain locations, ditches, and creek banks, but also threaten open woodlands, fields, and prairies. Because seeds prefer bare soil for germination, the plant is often found on disturbed sites, such as roadsides, fence lines, old fields, hayfields, construction sites, weedy meadows, and other non-crop areas. The plant may also spread rapidly into urban locations and managed areas such as parks. Reproduction and Dispersal. Flowers are wind-pollinated. Seeds mature in the autumn, when growth of the vine slows. After plants are killed by the first hard frost, vines disintegrate and decay. Seeds may be carried long distances by animals, people, machinery, and waterways. Seeds begin to germinate in early spring, and continue to do so all summer as long as conditions are sunny and moist. Seedlings can remain dormant in the cotyledon stage for several weeks. When the weather turns hot, seedlings rapidly grow into long vines. Seeds remain viable for three years. Impacts. With several thousands of plants per acre, Japanese hops can blanket large areas of open ground or low vegetation. Its rapid growth in summer enables it to grow long stems that overtop other plants, such as understory shrubs and small trees in woodlands. It can create dense mats that are several feet thick. Its weight can cause host plants to topple over or break, and the twining habit can also girdle plants. It displaces native species by blocking light to existing plants and preventing seedling growth, especially in riverbank and floodplain locations. The prickles are irritating, and contact with plants may cause dermatitis or blistering in some people. In China and Korea, pollen concentrations cause symptoms of asthma and allergic rhinitis, a problem that could be increased if Japanese hops continues to increase its range in the United States. Management. Because both hops species are common garden or commercial plants, little information is available regarding their control. Any eradication efforts should be continued

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for at least three years to ensure the elimination of all seeds in the seed bank. Because Japanese hops requires bright light, maintenance of a closed tree canopy will prevent its invasion. Vines use weeds and low branches as “ladders” to reach shrubs and small trees. If appropriate to the site, weeds and low branches can be removed. Although Japanese hops will grow and overtop grasses once started, they do not germinate well in sod-covered grasslands. Maintenance of grassland pastures might prevent infestations. Any machinery used for eradication should be thoroughly cleaned. Because it is slow and labor intensive, physical removal is appropriate only for small stands. The annual plants can be pulled any time of year before seed develops. Although the root system is not deep or extensive, allowing plants to be easily pulled out, the roots must be removed because buds will sprout. Physical removal should be done early in spring, when the roots are small and before vines become entangled in other vegetation. Because seeds germinate all summer, removal should be done monthly. Repeatedly cutting or mowing plants close to the ground surface until they die in the autumn is effective because it prevents seed production. All root and stem pieces should be removed from the site. Burning is inappropriate because the vines would carry the fire into the tree crowns. Chemical applications of both preemergents and postemergents are effective. Application of preemergents can be done around young trees in plantations or restoration projects, but not in natural woodland. When applied in spring, sulfometuron methyl proved to be the most long-lasting preemergent. Postemergent herbicides should be applied in April and May, after most Japanese hops seeds have germinated, but before the vines grow enough to cover vegetation and before new seeds mature in August. Metsulfuron methyl and glyphosate offer the best control, but plants may resprout from the roots if they are insufficiently damaged. Although some insects and pathogens attack or feed on Japanese hops, the introduction of biological control agents is unlikely because of the importance of common hops as a crop. Although Japanese hops is susceptible to hop latent carlavirus and Humulus japonicus ilarvirus, both transmitted by aphids, these viruses also infect common hops. Two moths (Epirrhoe sepergressa and Chytonix segregata) and a fungus (Pseudocercospora humuli), natural enemies of Japanese hops in Asia, are being studied. The Japanese beetle (Popilla japonica) feeds on hops but does little damage.

Selected References Hilty, John. “Japanese Hops (Humulus japonicus).” Weedy Wildflowers of Illinois, 2010. http:// www.illinoiswildflowers.info/weeds/plants/jp_hops.htm. Pannill, Philip D., Aaron Cook, Anne Hairston-Strang, and Jil M. Swearingen. “Japanese Hop.” Weeds Gone Wild: Alien Plant Invaders of natural areas. Plant Conservation Alliance’s Alien Plant Working Group, 2009. http://www.nps.gov/plants/alien/fact/pdf/huja1.pdf. Renz, Mark. “Japanese Hops, a New Weed Species to Be Aware of in Wisconsin.” Wisconsin Crop Manager Newsletter. Integrated Pest and Crop Management (IPCM), University of Wisconsin, 2008. http://ipcm.wisc.edu/WCMNews/tabid/53/EntryId/623/Japanese-hops-a-new-weed-species -to-be-aware-of-in-Wisconsin.aspx. Steffen, Brad, and Bob Edgin. “Japanese Hops (Humulus japonicus Sieb. & Zucc.) Species Character.” Vegetation Management Guideline 1(40): 2007. Illinois Nature Preserves Commission (INPC), Illinois Department of Natural Resources (DNR). http://dnr.state.il.us/inpc/pdf/VMG%20Japanese %20hops%20original%202007.pdf.

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n Kudzu Also known as: Japanese arrowroot Scientific name: Pueraria montana Synonyms: Dolichos lobatus, Dolichos hirsutus, Pueraria hirsuta, P. lobata, P. pseudohirsuta, P. Thunbergiana, P. triloba Family: Pea (Fabaceae) Native Range. Eastern Asia, including China, Korea, Japan, Taiwan, and Southeast Asia. Distribution in the United States. Widespread in the eastern states, as far north as Illinois, Michigan, and Maine, west to Texas, Oklahoma, Kansas, and Nebraska. Plants have also been reported in Portland, Oregon, and in Washington State. Also in Hawai’i. The worst infestations are in the southeastern states. Description. Kudzu is a perennial twining or climbing woody vine. It produces extensive mats that cover all other vegetation, including tall trees. New growth vines are pubescent and as much as 0.5 in. (1.3 cm) in diameter. Vines become fibrous as they age, and can be as much as 6 in. (15 cm) in diameter and as long as 100 ft. (30 m). Very old stems may be 12 in. (30 cm) in diameter. Leaves, supported by petioles 2–4 in. (5–10 cm) long, are alternate and compound. Each of the three heart-shaped leaflets is 3–7 in. (7.5–18 cm) long and can be either entire or two- or three-lobed. The herbaceous stems, petioles, and underside of leaves are covered with tan or brown hairs. The plant is deciduous and not frost tolerant, dropping its leaves at the first frost in autumn. Although the leaves and new growth die, the dried leaves remain on the vine Because kudzu was formerly promoted by the federal government for erosion control, the plant is widespread in southern states. (Native as a dead mat. New growth range adapted from USDA GRIN and selected references. Introduced begins in May. Kudzu produces large, fleshy range adapted from USDA PLANTS Database, Invasive Plant Atlas of the United States, and selected references.) taproots or tubers, up to 7 in.

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(18 cm) in diameter and 6 ft. (2 m) or more long. Roots are typically 3.3–10 ft. (1–3 m) deep, but some can extend down as far as 16 ft. (5 m). Tubers, which can weigh up to 400 lb. (180 kg), store an abundance of carbohydrates to sustain the plants. Plants in full sun bloom from July to October. The fragrant flowers, which emit a grape-like aroma, are bright red-pink or purple pea-like florets, 0.5–1 in. (1.3–2.5 cm) long, clustered on 4–12 in. (10–30 cm) long racemes. They are common on upright or draped climbing vines but rarely occur on plants covering flat ground or other horizontal surfaces. Clusters of 20–30 bean-shaped hairy pods ripen in the fall but remain on the plant until January. Pods are 3 in. (8 cm) long and contain 3–10 hard flattened, kidney-shaped seeds up to 0.3 in. (8 mm) wide. Related or Similar Species. Four native legumes that also have three-lobed leaves may appear similar. Prostrate ticktrefoil, also called dollar leaf plant, is a forb, with leaflets that are glabrous and almost round. Leaves of American hogpeanut, which can be either a forb or a vine, are less pubescent. Its flowers are white or pale lilac, and the fruit is only 0.2 in. (5 mm) long. Leaves of amberique bean, also called trailing wild bean, are sparsely hairy on the lower surface and smaller. The plant can also be either a vine or a forb. The flowers form in small clusters, and the seed pods resemble green beans. Poison ivy, which can be a shrub, forb, or vine, climbs with adventitious roots and its leaflets are more distinctly lobed. Introduction History. Kudzu was introduced to the United States at the 1876 Centennial Exposition in Philadelphia and promoted as an ornamental because of its fragrant flowers. By 1900, rooted cuttings were available by mail order from an enthusiastic Florida farmer who planted 35 acres for hay and considered kudzu an ideal plant for livestock forage. From 1935 to the mid-1950s, it was promoted by the federal government for use in erosion control, especially in the impoverished soils of the Appalachian piedmont in Alabama, Georgia, and Mississippi. The Soil Conservation Service distributed 85 million seedlings. Farmers were paid up to $8 per acre to plant kudzu, and more than 1.2 million acres were planted. During the 1940s, kudzu clubs formed in honor of the vine. In the 1930s and 1940s, kudzu was also promoted as a high-nitrogen forage crop for livestock, but it proved hard to bale and cattle trampled the vines. The federal government removed kudzu from its list of acceptable cover plants in 1953, and in 1972, the U.S. Department of Agriculture declared it a noxious weed. Habitat. Kudzu grows under a wide range of environmental conditions and is present in a variety of ecosystems, from dry flatwoods to riparian zones. It can grow where the water table is high, but cannot tolerate flooded soils. Although it is found on many types of substrate, it grows best on well drained, acid to neutral soil, with a pH of 4.5–7. As a nitrogen fixer, however, it can thrive on poor soils. It prefers full sun but can exist on the floor of a closed-canopy forest because the vines climb trees to get enough light. The plant can invade agricultural land, forests, plantations, range, grassland, riparian zones, scrub, and urban areas as well as disturbed sites, such as abandoned fields and roadsides. Infestations seen around abandoned homesteads are probably from ornamental plantings gone wild. Although it is unable to root on healthy grass cover, the vines can overrun grass areas such as pasture. It grows best in temperate regions with mild winters, 40–60ºF (4.5–15.5ºC), summers above 80°F (26.5°C), and 40 in. (1,000 mm) or more of rainfall. Kudzu can survive both drought and cold winters because of its massive root reserves. Reproduction and Dispersal. Kudzu spreads almost exclusively by vegetative means, by runners and rhizomes that root at nodes. Pieces of the plant can be carried and subsequently deposited by vehicles, machinery, or flowing water. Although it grows best in wet climates, it is drought tolerant, resprouting from its massive root crowns. One root can have up to 30

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A. Kudzu can rapidly overtop and smother even tall trees. (James H. Miller, USDA Forest Service, Bugwood.org.) B. The three leaflets may have entire margins. (James H. Miller, USDA Forest Service, Bugwood.org.) C. In the variety lobata, leaflets are lobed. (Ted Bodner, Southern Weed Science Society, Bugwood.org.) D. Pea-shaped flowers are clustered on long racemes. (Forest and Kim Starr, U.S. Geological Survey, Bugwood.org.) E. The large tubers store carbohydrates for the vines. (Forest and Kim Starr, U.S. Geological Survey, Bugwood.org.) F. Vines climb by twining around other plants. (Rebekah D. Wallace, Bugwood.org.) G. Seed pods are hairy. (Ted Bodner, Southern Weed Science Society, Bugwood.org.)

vines growing from it. Wherever nodes touch the soil, the vine will root and produce new root crowns, as many as one in every 1–2 sq. ft. (5–10/m2). The result can be thousands of plants in a dense stand. Vines can grow more than 1 ft. (0.3 m) in a day, and 65–100 ft. (20–30 m) in a year. Flowers appear in the late summer or early fall of the plant’s third year of growth. Although kudzu is capable of producing abundant seeds, seed counts vary from zero to 180 per sq. ft. (0–1,800/m2) of soil. Insect damage may be responsible for low seed counts. Seeds are dispersed by mammals and birds. Although few seeds are viable, they remain so for many years and are probably responsible for long-distance migration. Seeds do not easily germinate and require scarification. Seedlings are poor competitors. Impacts. Kudzu kills trees and other vegetation by smothering the plants and blocking all light. Vines girdle tree trunks, and the weight of the plant breaks branches and uproots trees, disrupting entire ecosystems and rendering the land useless. The weight of the vines can also cause power lines and buildings to collapse. Kudzu is a problem on more than seven million acres (2.8 million ha.) in the southeastern United States, and it is estimated by the Congressional Office of Technology that $50 million is lost in land productivity every year. Costs of controlling kudzu may exceed the productivity value of the land it covers. Expenditures of power companies to clear vines off utility lines are estimated at $1.5 million per year. Recent studies suggest that kudzu increases ozone pollution. As a nitrogen fixer, kudzu alters the nitrogen content of soils and doubles soil emissions of nitric oxide. The plant also emits large amounts of isoprene, a volatile organic compound (VOC). Nitric oxides and VOCs in the atmosphere chemically react with sunlight to create ozone, a major component of smog. Atmospheric modeling predicts a 50 percent increase in the number of unhealthy high-ozone days attributed to kudzu infestations.

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Are There Uses for Kudzu?

K

udzu has traditional culinary and herbal uses in Japan and in China, and it has also been used to reduce hypertension. It currently is being studied as treatment for alcoholism because it appears to reduce the craving. Kudzu can produce forage for livestock, with a carrying capacity of one cow per acre. Goats will also feed on the vines.

Management. Preventing the spread of kudzu depends on proper cleaning of all vehicles and equipment that come into contact with the plant, because pieces will root and may be carried in soil and on vehicles. Successful eradication of kudzu requires that the root system be destroyed, a process which requires persistent treatment and may take 10 years. Physical means of control that remove the vines may not be effective without follow-up applications of herbicides on root crowns. Digging out plants is difficult because of the large tubers, and is best used only for small, initial infestations. Repeated grazing by cattle, or more effectively by goats, over several years may remove the foliage, causing depletion of the energy stored in the roots. Mowing or cutting may do the same. Cut vines can be used as livestock feed, burned, or placed in plastic bags in a landfill. Burning the upper growth promotes seed germination, and new sprouts must be eliminated. Chemical control can be achieved by applying systemic herbicides, either glyphosate or triclopyr. Spraying of foliage can be used in large populations where saving native plants is not possible, but the root crown must also be treated. After locating the tuber by following the stems, workers should cut into the root crown and apply the herbicide to not only the root crown but also to any runners in the soil. Where it is desirable to preserve native vegetation in a mixed forest, kudzu can be selectively cut to stumps 2 in. (5 cm) above ground level, for immediate application of the herbicide. With either method, new sprouts must also be sprayed soon after emergence. Biological control is being investigated and surveys are being conducted for insects in kudzu’s native range. Some potential candidates have been rejected because they would also feed on crops. Possibilities include leaf-feeding beetles, sawflies, stem-boring weevils, and a large beetle that lays eggs on the main vines and roots. A fungal pathogen (Synchytrium puerariae) from southern China may have potential. Three pathogens native to North America, a bacterium (Pseudomonas syringas pv. Phaseolicola), a fungus (Myrothecium verrucaria), and Colletotrichum gloeosporioides, have also been studied. The fungus, from the sicklepod plant (Senna obtusifolia), has effectively killed kudzu in both greenhouse and field studies.

Selected References Bergmann, Carole, and Jil M. Swearingen. “Kudzu.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2009. http://www.nps.gov/plants/ alien/fact/pumo1.htm. Britton, Kerry O., David Orr, and Jianghua Sun. “Kudzu.” In Biological Control of Invasive Plants in the Eastern United States, by R. Van Driesche et al. USDA Forest Service Publication FHTET-2002-04, 2002. http://www.invasive.org/eastern/biocontrol/25Kudzu.html. “Kudzu.” Southeast Exotic Pest Plant Council Invasive Plant Manual, n.d. http://www.se-eppc.org/ manual/kudzu.html.

626 n VINES “Kudzu (Pueraria lobata).” Washington State Noxious Weed Control Board, March 2007. http:// www.nwcb.wa.gov/weed_info/Pueraria_lobata.html. Samarrai, Fariss. “Invasive Kudzu Is Major Factor in Surface Ozone Pollution, Study Shows.” Top News from the University of Virginia, 2010. http://www.virginia.edu/uvatoday/newsRelease.php ?id=11862.

n Mile-A-Minute Also known as: Asiatic tear-thumb, devil’s tail tear-thumb, mile-a-minute weed Scientific name: Persicaria perfoliata Synonyms: Polygonum perfoliatum; Polygonum arifolium var. perfoliatum Family: Buckwheat (Polygonaceae) Native Range. Southern and eastern Asia, from India east to China, and north to far eastern Russia and Korea. South to Vietnam, Thailand, and the Malay Peninsula. Also Japan, the Ryukyu Islands, Taiwan, and the Philippines. Distribution in the United States. Mile-a-minute is currently localized in the eastern states, from New York and Massachusetts south to North Carolina, centered on the introduction site in southern Pennsylvania. Description. Mile-a-minute is an annual, herbaceous, trailing vine with green stems that become reddish with age. The plant’s height varies with the site. In open areas, it becomes a dense mat, but vines will climb as high as 26 ft. (8 m) on trees at forest edges. Except where they become woody at the base, the elongated and branched stems are slender and delicate. Stems, leaf veins, and petioles are covered in 0.04–0.08 in. (1–2 mm) curved barb-like spines. The pale-green leaves are thin, alternate on the stem, and form distinct equilateral triangles, 1.5–2.8 in. (4–7 cm) long and 2–3.5 in. (5–9 cm) wide. Cup-shaped structures, called ocreas, form sheaths, 0.4–0.8 in. (1–2 cm) in diameter, which encircle the stems at the nodes. Vines die back with the first fall frost. Roots are shallow and fibrous. Flower buds, and subsequently the fruit, emerge from inside the ocreas, either on the ends of stems or in the axils of the upper leaves. Inflorescences are spike-like clusters of 10–15 tiny, inconspicuous white flowers, 0.1–0.15 in. (3–4 mm). After bloom, the calyx thickens to produce a metallic blue segmented berry-like fruit 0.2 in. (5 mm) in diameter. Each segment holds a single shiny black seed, 3 mm in diameter. Related or Similar Species. Many species of Persicaria, Polygonum and other genera in the buckwheat family occur in North America, both native and introduced, but none resembles mile-a-minute. Introduction History. Mile-a-minute was first recorded in the United States in 1890, from an herbarium specimen in Portland, Oregon, but the plant did not become established. It was accidentally brought to a plant nursery in southern Pennsylvania in the 1930s, when imported holly seeds were planted. It was also introduced into a garden in Maryland, where

World’s Worst 100?

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his plant, Persicaria perfoliata, is not the same as mile-a-minute (Mikania micrantha), which is in the Asteraceae and on the list of 100 of the World’s Worst Invasive Alien Species.

MILE-A-MINUTE n 627

it has since been eradicated. Interested by the new plant, the nursery owner in Pennsylvania allowed it to grow. It has since escaped cultivation and expanded its range approximately 300 mi. (480 km) in every direction, and continues to spread. Habitat. Because mile-aminute is an early successional species in its native range, it most often invades bare ground and disturbed areas, such as roadsides, edges of woodland, forest openings, orchards, riparian sites, drainage ditches, and fallow fields—any open, sunny site. It is quick to invade sites that have been treated with herbicides to clear brush, such as kudzu sites and utility corridors. Although it can grow on drier sites, it prefers moist soil and even tolerates very wet sites with poor soil structure. Plants also grow in urban locations, recreational areas, and plant nurseries. Although it tolerates some shade, it satisfies its light requirement by climbing on top of existing vegetation. Although mile-a-minute vine has thus far been contained relatively close As a temperate or subtropi- to its point of introduction in Pennsylvania and Maryland, it has the cal species, it can invade cli- potential to greatly increase its range. (Native range adapted from USDA mates with moderately cold GRIN and selected references. Introduced range adapted from USDA winters. Eight weeks of temper- PLANTS Database, Invasive Plant Atlas of the United States, and selected references.) atures 50ºF (10ºC) or below are necessary for seed germination. After the cold period, seeds germinate in both spring and summer at temperatures ranging from 40º to 68ºF (4.5–20ºC). Although it was formerly believed to persist as a perennial in mild climates that lack frost, that possibility has been disproved. Reproduction and Dispersal. Mile-a-minute plants have a long flowering season, June to October, and flowers are self-pollinating. They are prolific seed producers. Fruit usually develops from August to the date of the first frost, usually October, but, depending on site conditions, can develop as early as June. Seeds are dispersed by birds, insects, and small mammals. Birds disseminate seeds under utility lines, fence lines, and other perching locations. Ants have been seen carrying seeds short distances, and chipmunks, squirrels, and deer also eat the seeds. Because vines frequently overhang streams, water provides a

628 n VINES

A. Climbing vines can overtop other vegetation. (Leslie J. Mehrhoff, Ecology and Evolutionary Biology University of Connecticut, Bugwood.org.) B. Plants, with distinctly triangular leaves, may form a dense mat in open areas. (Britt Slattery, U.S. Fish and Wildlife Service, Bugwood.org.) C. The ocrea completely encircles the stem. (Leslie J. Mehrhoff, Ecology and Evolutionary Biology University of Connecticut, Bugwood.org.) D. Flowers and fruit emerge from the ocrea. (Richard Old, XID Services, Inc.). E. Stems are covered with barb-like spines. (Richard Old, XID Services, Inc.)

significant means of transportation in riparian locations, especially during storm events. Fruits remain buoyant for 7–9 days. The population in North Carolina may have originated from seeds floating down stream. Although newly discovered in summer of 2010, this new infestation may already be too large and dispersed to eradicate. Most seeds germinate in full sun in early spring. Impacts. This rapidly growing vine smothers herbs, shrubs, and small trees. The intertangled mat of vines covers all vegetation, blocking their foliage from light, thereby killing them because they cannot photosynthesize. Mile–a–minute causes a reduction in plant diversity, resulting in less food and shelter for wildlife. The vine has an economic impact because it is a threat to pine plantations, reforestation efforts, and Christmas tree farms, quickly smothering seedlings. It can also overrun plants in commercial nurseries and orchards. The densely spiny plant is a hazard in urban and recreational areas. Plants are also considered a weed harmful to agriculture in some parts of its native range. Management. The best way to prevent infestations of mile-a-minute is to maintain the stability of the native plant communities and avoid creating gaps where it can invade. Intact vegetative cover along streams, roadsides, and other corridors provides no bare ground for the plant to gain a foothold. Because the root system is weak and not persistent, small vines can be removed by physical means. Hand-pulling should be done while plants are still young, before the curved spines harden, and before seeds mature. Pulling vines that contain fruit may result in a dispersal of more seeds. Repeated mowing or cutting the vines close to the ground will reduce or prevent seed production. Because they do not resprout or root, severed vines can be rolled up and left to dry. The most effective chemical control is glyphosate, which kills existing plants, followed by a preemergent, such as imazapyr or atrizine, early the following spring to prevent germination of seeds. Because seeds are persistent in the soil bank, remaining viable for as long as six years, several applications of herbicide applications are necessary. Although some insects feed on mile-a-minute, no native species does significant damage. Of approximately 100 natural enemies in China, a few show promise for effective biological control. A weevil (Rhinoncomimus latipes), which is host-specific to mile-a-minute, was

ORIENTAL BITTERSWEET n 629

Preventing Spread

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lthough mile-a-minute is currently concentrated around the area where it was first introduced, it is present in only 20 percent of its potential range. Several other states provide suitable climate conditions. The mature plant, an annual with a shallow root system, is readily killed by herbicides and will not resprout. Its seeds have no means of extremely long-distance dispersal to widely disjunct locations across the United States except by human activity. If people are diligent about eliminating the plant when it first appears and are extremely careful not to transport seeds, the spread of this invasive species can be halted.

released into affected eastern states at various times beginning in 2004 and continuing to the present, with planned releases for 2011. This weevil produces several generations from spring to fall, with adults feeding on foliage, and larvae boring into the plant stems. Reports of a second weevil (Homorosoma chinensis) were subsequently found to be a misidentification of R. latipes. Two geometrid moths (Timandra griseata and T. convectaria) feed on young leaves and buds, defoliating the plants. Adults and larvae of a bug (Cletus schmidti) eat the skin of the fruit, exposing and damaging the developing seed. Although some of these insects will attack other species in the buckwheat family, their feeding preference is mile-aminute. A sawfly (Allantus nigrocaeruleus) and fungal pathogens are also undergoing research.

Selected References Okay, Judith A. Gerlach, Judith Hough-Goldstein, and Jil M. Swearingen. “Mile-A-Minute, Persicaria perfoliata.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2009. http://www.nps.gov/plants/alien/fact/pdf/pepe1.pdf. “Pest Alert, Mile-A-Minute Weed (Persicaria perfoliata).” U.S. Department of Agriculture, Forest Service, Northeastern Area, State and Private Forestry. Newtown Square, PA, 2009. http:// www.na.fs.fed.us. Wu, Yun, C. Readon, and Ding Jian-qing. “Mile-a-Minute Weed.” In Biological Control of Invasive Plants in the Eastern United States, by R. Van Driesche et al. USDA Forest Service Publication FHTET-2002 -04, 2002. http://www.invasive.org/eastern/biocontrol/26MileAMinute.html.

n Oriental Bittersweet Also known as: Round-leaved bittersweet, Asian bittersweet, Asiatic bittersweet, climbing spindleberry Scientific name: Celastrus orbiculatus Synonyms: Celastrus articulatus Family: Staff-tree (Celastraceae) Native Range. Temperate East Asia, including eastern Mongolia, northeastern China, Korea, and Japan. Distribution in the United States. The eastern half of the United States, from Minnesota south to Louisiana, east to Georgia and South Carolina, and north to Maine. It is cultivated in the Pacific Coast states, but has not yet been reported as naturalized in that region.

630 n VINES Description. Oriental bittersweet is a deciduous, woody perennial vine or trailing shrub. With no tendrils or adventitious roots, it climbs vegetation and structures by twining around the object for support. Its lightor dark-brown twigs are round and glabrous, with noticeable lenticels that appear as raised whitish corky dots. Older branches become olive drab or pale gray-brown with elongated lenticels and a scaly or shredded appearance. Branches can climb as high as 60 ft. (18 m) and can be as much as 5 in. (13 cm) in diameter. Leaves are variable in size and shape, but are generally broadly oblong or almost round, 1–5 in. (2.5– 12.5 cm) long and 0.5–3 in. (1.5–8 cm) wide. Leaf bases are generally obtuse, while leaf tips are acute to rounded. The glossy, finely toothed leaves, alternate on the stem, are supported on light-green petioles, 0.4–1.2 in. (1–3 cm) long. In fall, leaves turn lemon- to golden-yellow, enabling plants Although Oriental bittersweet is cultivated as an ornamental in the to be seen after most other western states, it has only become naturalized and invasive in the deciduous leaves have fallen. Midwest and East. (Native range adapted from USDA GRIN and selected The outer surfaces of the roots references. Introduced range adapted from USDA PLANTS Database, are a bright orange. Invasive Plant Atlas of the United States, and selected references.) Oriental bittersweet can be either dioecious or monoecious. In May and June, clusters of 3–7 small, inconspicuous flowers grow from the leaf axils. The greenish-white or greenish-yellow flowers initially have both male and female parts, but one type is aborted or reduced, resulting in unisexual flowers and unisexual plants. A few vines, however, retain both types of flowers. Flowers have five petals and, if male, five stamens. Many clusters of fruit, which are usually shorter than the leaves, develop at many points along the stem. The fruit is a globular capsule, approximately 0.25 in (7 mm) in diameter, with an outer covering that changes from green to bright yellow as it ages. The mature yellow capsule splits open to reveal three red-orange fleshy arils, each with 1–2 brown or yellow seeds. The three parts of the capsule become folded back, looking like three yellow wings behind the arils. Related or Similar Species. The native American bittersweet, which grows in similar habitats, is differentiated by flowers and fruit. Plants have a single panicle of flowers at the tips of

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A. Vines climb by twining around objects. (James H. Miller, USDA Forest Service, Bugwood.org.) B. Older and larger vines can girdle and kill their hosts. (Chris Evans, River to River CWMA, Bugwood.org.) C. Leaves are usually oblong or round, with pointed tips. (James H. Miller, USDA Forest Service, Bugwood.org.) D. Fruit are round capsules. (James R. Allison, Georgia Department of Natural Resources, Bugwood.org.) E. Clusters of inconspicuous flowers grow from leaf axils. (Leslie J. Mehrhoff, Ecology and Evolutionary Biology University of Connecticut, Bugwood.org). F. The three parts of the capsule fold backward to look like wings. (James R. Allison, Georgia Department of Natural Resources, Bugwood.org.)

the stems, and the clusters of flowers and fruit are approximately the same length as the leaves. The plant has fewer fruit, but in larger clusters, and the fruit is orange when ripe. Although identification by leaf shape and size is not reliable, leaves of American bittersweet tend to be twice as long as they are wide, and tapered at each end. Hybrids occur between American bittersweet and Oriental bittersweet. Introduction History. Oriental bittersweet was bought to the United States in the 1860s as an ornamental. It is often associated with old homesites, from where it has escaped to natural areas and has become naturalized in several states. Oriental bittersweet itself, or a plant mistaken for the American bittersweet, was also used extensively as highway landscape plantings and for erosion control. It has been promoted as enhancement for wildlife, providing food and cover. The fruit is showy and attractive, and fruiting branches are frequently used in floral arrangements. It is still available in the horticultural trade, often mislabeled as American bittersweet. Habitat. Oriental bittersweet has wide environmental tolerances. It grows at the edges of forests and marshes, in woodlands and coastal areas, along hedgerows, and in fields in the early successional stages. It is especially prominent in disturbed sites in meadows, thickets, beaches, and young forests. It grows best in open, sunny sites, but is tolerant of shade and can invade dense canopied forests. It can grow at elevations as high as 7,250 ft. (2200 m). Reproduction and Dispersal. Oriental bittersweet reproduces both by seed and by root suckering. Flowers are pollinated by bees and by wind. Fruit remains on the vine throughout the winter, providing food for several birds, such as Black-capped Chickadees, Mockingbirds, Blue Jays, and European Starlings, as well as for small mammals, all of which distribute the seeds. Human use of the fruiting stems in dried flower arrangements also contributes to dispersal, as old branches are disposed of in compost or discarded in brush. Seeds germinate in late spring. Oriental bittersweet produces copious root suckers from rhizomes, especially when the plant is damaged or cut. Clones or thickets can evolve from only one or a few plants.

632 n VINES Impacts. Because it grows quickly and sprouts from its roots, Oriental bittersweet commonly creates monotypic stands. This aggressive vine threatens both understory and canopy plants of forested and open areas. By climbing and overtopping plants, it kills them by girdling and preventing photosynthesis. The weight of the vine can cause host plants to become uprooted during high wind or heavy snows. Although the plant is most noticeable along roadsides, its greatest impact is in forests, where it resembles kudzu in the way it blankets existing vegetation. It outcompetes and displaces the native American bittersweet. The germination rate of Oriental bittersweet averages 70 percent, compared with 20 percent for American bittersweet, especially at low light intensities. Evidence exists that Oriental bittersweet is able to recover more quickly from grazing than native bittersweet does, giving it a further advantage. Hybridization between the two species threatens the genetic identity of American bittersweet, a plant that is becoming increasingly rare. Because the plant can grow in pure sand, Oriental bittersweet vines may spread into bird nesting areas on beaches or alter dune formation. By doing so, it may threaten the breeding behavior of the Piping Plover, a federally threatened species, on Long Island Sound. Fruit of the Oriental bittersweet is toxic to humans. Management. A combination of physical and chemical methods works most effectively. It is questionable, however, whether infested natural areas can recover after removal of Oriental bittersweet because of too many vegetative changes and disruptions to the natural ecosystem. Clonal thickets are especially hard to kill. After a 250 sq. ft. (25 m2) plot was treated with triclopyr in 1986, the area recovered to produce over 50 sprouts each subsequent year. It took six years to exhaust the seed bank. Re-infestation of any area is possible from other sources through long-distance dispersal of seeds. Physical control can be accomplished by hand-pulling small plants, including the entire root system, before fruit matures. If fruit is present, plants should be bagged and disposed of, to prevent seed dispersal. An alternative method is to leave the bag in the sun to bake, which will kill any seeds. On climbing vines, the best method is to sever the vines and treat the rooted base with herbicide. Cutting dense, low-growing patches close to the ground in early spring, followed by spraying new growth after about a month, can completely kill the plants. For large infestations, especially where pulling or uprooting vines would do too much damage, chemical applications of glyphosate or triclopyr are effective. Foliar sprays, which are also absorbed through the basal bark of the vines, are best done in fall after nontarget plants become dormant. Foliage of new seedlings may also be sprayed. Although herbicides may be applied directly to basal bark of the plants, chemical treatments work best when applied to cut stems. Application should be done in fall and winter, before ephemerals emerge in spring, to avoid damaging native plants. Repeated treatments may be necessary. Because it targets only broadleaf plants, triclopyr is preferred where nontarget vegetation includes grasses, sedges, and members of the lily family. No biological controls are known.

Selected References Burnham, R. J. “Plant Diversity Website, Celastrus orbiculatus.” CLIMBERS Website, 2010. http://www -personal.umich.edu/~rburnham/SpeciesAccountspdfs/CelascanCELAFINAL.pdf Dreyer, Glenn D. “Element Stewardship Abstract, Celastrus orbiculatus.” Global Invasive Species Team, Nature Conservancy, 1994; modified 2009. http://wiki.bugwood.org/Celastrus_orbiculatus.

PORCELAINBERRY n 633 Swearingen, Jil M. “Oriental Bittersweet.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2006. http://www.nps.gov/plants/alien/ fact/pdf/ceor1.pdf.

n Porcelainberry Also known as: Porcelain vine, porcelain ampelopsis, creeper, wild grape, Amur peppervine Scientific name: Ampelopsis glandulosa var. brevipedunculata Synonyms: Ampelopsis brevipedunculata, Cissus brevipedunculata, Vitis brevipedunculata, Ampelopsis heterophylla Family: Grape (Vitaceae) Native Range. Extreme northeastern China. Distribution in the United States. Eastern states, from Wisconsin and Iowa south to Alabama and Georgia, and north to New York and New Hampshire. Especially invasive in the northeastern states. Description. Porcelainberry is a woody perennial vine. It climbs by using twining, nonadhesive tendrils, which grow opposite the leaves. Although vines are mature at approximately 10 ft. (3 m) long, they can climb as high as 20 ft. (6 m). Plants running along the ground have an upright, spreading habit, and may form a dense matted ground cover. Vines need support in order to climb. The thin green twigs grow in a slightly zigzag pattern for the first year and become brown and semi-woody in their second season. The white stem pith is continuous across the stem nodes. The bark has lenticels and does not peel. Leaves, alternate on the stem, are broadly oval and palmate in shape, 5 in. (12.5 cm) long. Leaves may be either shallowly or prominently cleft, forming 3–5 coarsely toothed lobes. Plants with the deeper lobes are known as the variety Ampelopsis glandulosa var. heterophylla (formerly A. brevipedunculata var. maximowczii). The leaf base is heart-shaped, and the tip may be either rounded or pointed. Leaves are shiny, ranging from medium to dark green to blue-green. Leaves may have delicate hairs along the veins, and young twigs and petioles are hairy. Porcelainberry is deciduous, but leaves do not change color in fall. The taproot is large and vigorous. The small, inconspicuous creamy-green flowers appear June through September on the current season’s growth. They are densely arranged in cymes opposite the leaves. The fruit are hard berries, hanging in small, globular clusters. They change color as they mature and can be white, yellow, green, lilac, purple, turquoise, sky blue, or bright blue. Dots give the fruit a speckled or marbled appearance. Because of the long flowering season, all colors of fruit may occur on the vine, or even in one cluster. Each small fruit, 0.25 in. (0.6 cm), which matures in September or October, contains 2–4 seeds. Related or Similar Species. A cultivar, known as ‘Elegans,’ is a deeply lobed and variegated plant available in nurseries. It has smaller leaves that are mottled with white and sometimes pink coloration, and is less vigorous and invasive than the species. Boston ivy, also known as Japanese creeper, is a deciduous, climbing vine native to Asia. It has simple lobed leaves with serrated edges and hairy leaf veins. It can be distinguished from porcelainberry by adhesive tips on the ends of the tendrils, blue fruit on red pedicels, and foliage that turns red in the fall. Two native species of Ampelopsis are widespread in the southeastern United States. Peppervine is a ground cover or climbing vine that has few tendrils. It is invasive in some

634 n VINES regions. This plant is easily distinguished by its bi- or tripinnately compound foliage, which turns pale yellow in the fall. The inedible berries are bluish purple, becoming black and shiny as they ripen. Heartleaf peppervine uses tendrils, including twining flower stems, to climb trees in riparian sites, but it is not invasive. The broadly oval leaves, as much as 5 in. (12.5 cm) long and 4 in. (10 cm) wide, are not lobed and have a heart-shaped base. Berries are purple. Although porcelainberry resembles native grapes, grape vines have distinguishing characteristics. Grape pith is dark brown and is not continuous across stem nodes. The bark peels and has no lenticels, and flowers occur in panicles. Introduction History. Porcelainberry was introduced to the United States in the 1870s as a landscape plant because of its colorful berries. It also makes a good ground cover or trellisclimbing vine and was used as Found in the upper midwestern and eastern states, porcelainberry prefers a bedding plant and screening moist soils but is tolerant of drought (Native range adapted from USDA plant. The variety ‘Elegans’ was GRIN and selected references. Introduced range adapted from USDA brought to the United States PLANTS Database, Invasive Plant Atlas of the United States, and selected before 1847, either by direct references.) plantings or mixed in bird seed. Pest resistant and tolerant of adverse conditions, porcelainberry plants are still available in the horticultural trade. Habitat. Porcelainberry grows in several habitats, including disturbed sites, such as abandoned fields, vacant lots, and road, railroad, and utility right-of-ways. It can also be found at forest edges, pond margins, along stream banks, in pastures, and in successional or planted forests. It grows on most types of soil, rich to poor, and with various levels of acidity or alkalinity. It prefers moist soil, but does not tolerate sites that are permanently wet. Plants can withstand both drought and heat. Although it can be found in full sun to partial shade, porcelainberry is less tolerant of heavy shade and absent from mature forest interiors. Elevation limits are 500–2,000 ft. (150–600 m). Reproduction and Dispersal. Porcelainberry reproduces both by seeds and vegetatively. Birds and small mammals, such as squirrels, eat the berries and expel the seeds. Uneaten

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A. Vines climb into tree canopies. (Steven Manning, Invasiveplantcontrol.com.) B. and C. Depending on the variety, leaves may be deeply or shallowly lobed. (James H. Miller, USDA Forest Service, Bugwood.org.) D. Tiny flowers grow in cymes. (James H. Miller, USDA Forest Service, Bugwood.org.) E. Berries hang in small clusters. (James H. Miller, USDA Forest Service, Bugwood.org.) F. Old stems become semi-woody. (James H. Miller, USDA Forest Service, Bugwood.org.)

fruits split to release the seeds. Infestations that develop downstream from existing sites provide evidence that seeds may also be dispersed by water. Seeds germinate readily the following year, but some remain viable in the soil for several years. Plants resprout when the top portion is damaged or cut. Impacts. Porcelainberry invades both open and wooded habitats. Seeds grow well after a disturbance, either natural or human-caused. Its thick mat of vines cover and shade out native shrubs and small trees. The weight of the vines makes the host plant susceptible to wind and ice damage. When provided with high to moderate light and plenty of water, the plant spreads fast, and vines can grow 15 ft. (4.5 m) in one season. Management Any management program requires monitoring and follow-up. Some methods must be repeated, not only during the growing season but for several years. The major goal is to prevent flowering, fruiting, and production of mature seeds. Physical control includes hand-pulling vines in either fall or spring to prevent flowers the following summer. To avoid seed dispersal, vines should be pulled up before fruit matures. If the plant is in fruit, cuttings should be bagged and disposed of in a landfill. Large vines may be cut close to the ground and monitored for resprouts, pulling them soon after they emerge. Cutting vines in the fall will not prevent flower development because flowering occurs on the current season’s growth. Chemical treatment with herbicides may be necessary. Triclopyr or glyphosate may be applied to large vines that have been cut at ground level. Triclopyr is the most effective, either as a foliar spray or applied to cut plants. Applications of triclopyr ester to sections of stem 2–3 ft. (.6–1 m) long work well. Although 9 species of fungi and 13 species of arthropods are natural enemies of porcelainberry in its native range, no biological controls are available. Japanese beetles (Popillia japonica) attack landscape plants.

Selected References “Ampelopsis brevipedunculata.” The Ohio State University, n.d. http://www.hcs.ohio-state.edu/hcs/TMI/ Plantlist/am_ulata.html. “Porcelainberry, Amur Peppervine.” Invasive Plant Atlas of New England (IPANE), University of Connecticut, 2009. http://www.invasive.org/weedcd/pdfs/ipane/Ampelopsisbrevipedunculata.pdf.

636 n VINES Swearingen, J., K. Reshetiloff, B. Slattery, and S. Zwicker. “Porcelainberry.” Plant Invaders of MidAtlantic Natural Areas. National Park Service and U.S. Fish and Wildlife Service, 2002. http:// www.invasive.org/eastern/midatlantic/ambr.html. Young, Jamie. “Porcelain-berry.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2005. http://www.nps.gov/plants/alien/fact/ pdf/ambr1.pdf.

n Swallow-Worts Pale Swallow-Wort Also known as: Swallow-wort, swallowwort, European swallow-wort, dog-strangling vine Scientific name: Cynanchum rossicum Synonyms: Vincetoxicum rossicum, Cynanchum medium, Vincetoxicum medium, Antitoxicum rossicum Family: Milkweed (Asclepiadaceae) Black Swallow-Wort Also known as: Black dog-strangle vine, Louis’ swallow-wort, climbing milkweed Scientific name: Cynanchum louiseae Synonyms: Vincetoxicum nigrum Family: Milkweed (Asclepiadaceae) Native Range. Pale swallow-wort is native to the Ukraine and to southwestern European Russia, perhaps endemic to regions north of the Black Sea. Black swallowwort is from Mediterranean southwestern Europe, including Italy, France, Spain, and Portugal. Distribution in the United States. Midwestern and New England states. Pale swallowwort is more frequently found in the Great Lakes region and New England. Black swallowwort is more widespread, from Nebraska and Kansas east through New England, and has also been found in California. Description. Swallow-worts are long-lived, herbaceous perennial scramblers or vines that climb by twining slender stems around themselves or around other plants. Stems do not branch, and depending on the height of the supporting structure, they can grow 2–8 ft. (0.6–2.4 m) long. Typical of members of the milkweed family, stems and leaves exude a milky latex when cut. Pale swallow-wort stems have distinct lines of dense pubescence, which are absent or sparse in black swallow-wort. Black Swallow-worts were brought to the United States as ornamental plants. swallow-wort stems may turn (Native range adapted from USDA GRIN and selected references.) red in sunny locations. Dark-

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green leaves are oblong to oval or lance-shaped, 2–5 in. (5–13 cm) long and 0.5–3 in. (1.5–8 cm) wide. Leaf arrangement is opposite, and petioles are 0.2–0.8 in. (0.5–2 cm) long. Leaf tips are pointed, bases are rounded, and the margins are entire (not serrated). Upper leaf surfaces are glabrous and shiny, but lower surfaces, especially the veins, and leaf margins are pubescent. The pubescence on black swallow-wort leaves may be red. The largest and widest leaves grow in the middle of the vine, while the leaves at both the base and the growing tip are smaller. Both species have a fleshy, fibrous root system that is firmly anchored in the soil. Star-shaped flowers, appearing May through June, are small, approximately 0.25 in. (6 mm). They grow in small clusters of 4–20 in leaf axils. Open for 6–8 days, flowers emit a slight odor variously described as sweet or of rotting fruit. Petals of pale swallow-wort flowers are pale yellow-purple, creamy pink, or reddish brown. The flowers have a distinctly five-lobed pink, orange, or yellow ring, called a corona, surrounding pale green or yellowgreen stamens. Black swallow-wort flowers have purplish, almost black petals, with a maroon corona encircling bright yellow-green stamens. Petals of pale swallow-wort are glabrous, while the upper surface of black swallow-wort petals are covered with short, white hairs, giving the flower a downy appearance. Fruit are slender, tapered seed pods, 1.5–3 in. (4–8 cm) long and 0.25 in. (6 mm) wide, often occurring in pairs on the stem. When mature, they turn light brown and split along a longitudinal seam to release flat, brown seeds. Each seed has a thin membrane along its margins and a tuft of silky hair. Opened pods appear very silky inside. Although plants turn yellow in late summer and die back to the ground in winter, the dried stems may remain, often with open seed pods with remaining seeds. Related or Similar Species. White swallow-wort, native to most of Europe, grows sparsely in the northeastern United States. It does not seem to be invasive in most areas, but may be threatening green comet milkweed, an endangered species in Connecticut. Although the United States has several native Cynanchum species, honeyvine is the only one growing in the midwestern and northeastern United States where swallow-worts are found. Honeyvine has white flowers, and the bases of its leaves are distinctly heart shaped. Honeysuckles have distinctly pea-shaped flowers and semi-woody stems. Climbing nightshade, also an invasive species, has similar-looking star-shaped flowers but is distinguished by its berries and leaves, which are alternate and either serrated or lobed. Neither honeysuckles nor nightshade have latex. Introduction History. Although they are no longer desirable as ornamental plants, swallow-worts were probably brought to the United States for horticultural reasons. Pale swallow-wort was first collected in nature in New York State in 1897. Black swallow-wort was first collected from a natural area in Massachusetts in 1854, probably escaped from a botanic garden where it was a weed. Scattered occurrences of both species indicate that they were probably garden escapees, but swallow-worts are easily dispersed to new areas in contaminated hay. Habitat. Both swallow-wort species are found in similar habitats, primarily upland areas. They have a wide tolerance to light and moisture conditions, growing both in dry sunny locations and moist shaded locations, but avoid sites with long-standing water. Plants in shady sites, however, are less vigorous, with thinner stems, larger and darker leaves, and fewer roots. Swallow-worts grow in oak and mixed-hardwood forests, prairies, and along fencerows. Commonly found in disturbed sites, especially human-caused, they grow along transportation and utility right-of-ways, in quarries, and in abandoned pastures and agricultural fields. They also invade natural areas that have been disturbed, such as ice- or

638 n VINES flood-scoured river banks and talus slopes. Swallow-worts may dominate a shady understory for years, and when a disturbance opens the forest canopy, the plant will quickly grow, flower, and set seed. Swallow-worts are especially competitive and form large populations on shallow soils over limestone, areas prone to summer drought because the limestone fails to hold water after the surface soil dries. Plants are also found on deep, well-drained loamy soils. Black swallow-wort has a less distinct association with limestone and is also found on granitic substrate. This species also grows on rocky coasts, above the high-tide line, an indication that it is somewhat salt tolerant. Reproduction and Dispersal. Swallow-worts spread primarily by seed and are prolific producers. A thick stand in full sun can produce as many as 200 seeds per sq. ft. (2,000 per m2). The number of flowers and seed pods produced is directly Both swallow-wort species are found primarily in the upper midwestern related to the amount of light. and northeastern states, in sites disturbed by human activity. Plants in deep shade fail to (Introduced range adapted from USDA PLANTS Database, Invasive flower. Flowers are both selfPlant Atlas of the United States, and selected references.) pollinating and insect-pollinated, by bees, wasps, flies, ants, and beetles. Seeds are also polyembryonic, meaning that 1–4 plants can emerge from one seed. Long-distance dispersal is accomplished by wind-disseminated seeds. Many seeds are not viable. Greenhouse tests indicate that under normal conditions, the germination rate is less than 25 percent, and still less than 50 percent under ideal conditions. Some seeds germinate in fall, others in spring. In gardens, seedlings will flower and produce seed in their second year of growth. Both species sprout vigorously from dormant buds on the root crown when the top portions of the plant are damaged, and black swallow-wort spreads locally by rhizomes. Impacts. Swallow-worts grow in multi-stemmed clumps that outcompete native plants for soil moisture, nutrients, and light. Both species overtop plants in brushy areas and dominate the understory, but not the trees, of forests. They are problem weeds that require control in home gardens, perennial pastures, nurseries, and Christmas tree and other tree plantations, but they are usually not weedy in annual crops.

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A. Vines can cover and smother all other vegetation. B. Vines climb by twining around objects. C. Flowers of pale swallow-wort are light colored. D. Flowers of black swallow-wort are very dark purple. E. Seed pods are filled with silky filaments. (Leslie J. Mehrhoff, Ecology and Evolutionary Biology, University of Connecticut, Bugwood.org.)

Patches of swallow-wort displace or suppress native plant species and impact wildlife. Swallow-worts replace goldenrods and grasses in old fields and pastures, disrupting the process of natural succession. They threaten rare and endangered species. In at least one region in New York State, pale swallow-wort is displacing Hart’s tongue fern. In Vermont, black swallow-wort threatens Jesup’s milkvetch, an endangered endemic species. Also in New York State, swallow-worts threaten the rare and unique plant communities of limestone pavement barrens, called alvars. Plants modify the microbial community in the soil, thereby displacing the native species especially adapted to that environment. Neither swallow-wort species is readily used by native animals or insects. A study in New York State indicated that an increase in pale swallow-wort was followed by a decrease in native grassland birds. A Canadian study showed a decrease in diversity of ground and stem insects, and a total lack of gall-makers and miners. The effect of black swallow-wort on birds and insects is not known. Because they are in the milkweed family, swallow-worts may detrimentally affect monarch butterflies, which are obligated to lay their eggs on milkweeds. Eggs laid on swallow-worts do not survive. As swallow-worts become more dominant in the natural landscape, where they have displaced many Asclepia species necessary to the butterfly, populations of monarch butterflies could become endangered. Management. Early detection is important. Because swallow-wort produces so many seeds, if one plant is found, it is likely that more are nearby. Any management method should be carried out before seed sets. Because human activity may promote dispersal, areas that are actively releasing seed should be avoided, unless all the seeds can be collected. Any machinery or vehicles should be thoroughly cleaned to ensure that no seeds are carried away. If appropriate to the site, revegetation with grasses and subsequent spraying with a broadleaf herbicide to kill swallow-wort seedlings will eventually deplete the seed bank. Physical control is limited. Hand-pulling is less effective than digging out plants because the stem base is brittle, breaking off just above the root crown. Root crowns should be completely dug out because even a fragment may sprout a new plant. Any pod-bearing plants should be bagged and destroyed, taken to a landfill or burned. Mowing several times a year, when seed pods are small, will prevent seed formation, but timing is critical. If mowed during the flowering stage, plants will recover and sprout new stems. Although chemical treatments are best for large populations, the choice of herbicide is dependent on location and other plants. Herbicides should be applied after flowering begins but before seed pods form. At that time, plants are large enough to carry lethal doses of

640 n VINES herbicide to the roots, and no seeds will be produced. Because of the seed bank, several years may be needed to eradicate the population. Both glyphosate and triclopyr ester are effective, but glyphosate is better for cut stems. If seed pods are present, the stems with pods should be collected and bagged or seeds will continue to develop. Because foliar sprays may not penetrate the plant canopy, allowing seedlings and small plants to survive, repeated applications may be necessary. An alternative is to cut or mow plants that have seed pods and spray the regrowth in early fall. No biological controls are known for swallow-worts. Except for the tarnished plant bug (Lygus lineolaris), no insects or pathogens in the United States are prominent in swallowwort stands, and the plant bug does little damage. It is possible that swallow-worts may be toxic to North American insects. Little is known of natural enemies in their native range.

Selected References Lawlor, Fran. “Element Stewardship Abstract, Vincetoxicum nigrum and Vincetoxicum rossicum, Swallow-wort.” Global Invasive Species Team, Nature Conservancy, 2001; updated 2002. http:// www.invasive.org/gist/esadocs/documnts/vinc_sp.pdf. Sonday, ReBecca, and R. Burnham. “Plant Diversity Website: Cynanchum rossicum (Kleopow) Borhidi” and “Plant Diversity Website: Cynanchum louiseae Kartesz and Ghandi.” CLIMBERS Website, 2010. http://www-personal.umich.edu/~rburnham/climbers.html. Tewksbury, L., R. Casagrande, and A. Gassmann. 2002. “Swallow-Worts.” In Biological Control of Invasive Plants in the Eastern United States, by R. Van Driesche et al. USDA Forest Service Publication FHTET -2002-04, 2002. http://www.invasive.org/eastern/biocontrol/16SwallowWorts.html.

n Winter Creeper Also known as: Euonymus, dwarf euonymus, wintercreeper, climbing euonymus Scientific name: Euonymus fortunei Synonyms: Euonymus hederaceus, E. japonicus, E. japonicus var. acutus, E. radicans var. acutus, Elaeodendron fortunei, Family: Staff-vine (Celastraceae) Native Range. East-central China, Korea, Japan, and the Ryukyu Islands. Distribution in the United States. Scattered in the eastern and midwestern states, generally east of the Mississippi River, but also from Nebraska south to Texas and Louisiana north to Arkansas. From Wisconsin south to Alabama, east to Georgia, throughout the Atlantic coast north to Maine, and west to Michigan. Description. Winter creeper is an evergreen perennial with two growth habits. It can be a dense ground cover or shrub as much as 3 ft. (0.9 m) tall, or it can be a climbing vine. Aerial roots, used for climbing trees, rocks, and vertical structures, grow from stem nodes, enabling vines to climb as high as 40–70 ft. (12–21 m). Trailing plants also have many rootlets, which give the narrow stems a warty appearance. Initially lime green, the hairless stems become streaked with light-gray reddish bark as they age. Older stems have gray corky bark, at first fissured, then checkered with fissures. The broadly oval leaves, which are densely arranged and opposite on the stem, are 1–3 in. (2.5–8 cm) long and 1–1.8 in. (2.5–4.5 cm) wide. The thick, leathery leaves are smooth and glossy, with prominent silvery-white veins. Leaf blades are either dark green or green and white variegated on the upper surface. They are light green below. Leaf edges are finely serrated and slightly turned under or wavy. The leaf base tapers to the 0.1–0.4 in. (2–10 mm) petiole, and leaves are sometimes sessile.

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Long cymes of inconspicuous flowers, ranging in color from white to green, grow from leaf axils in June and July. Flowers are 0.1 in. (2–3 mm) in diameter, with five petals. Insect-pollination produces 0.25–0.5 in. (6–12 mm) pinkish to red, smooth capsules, hanging either singly or in groups of two. When ripe, September through November, the fruit splits to expose a single seed. Seeds are covered with a fleshy orange seed coat, called an aril. Related or Similar Species. Three Euonymus species are native to the eastern United States. Running strawberry bush, also called running euonymus, is a deciduous trailing shrub or prostrate vine with thin leaves. Its greenish-purple flowers are 0.2–0.3 in. (6– 8 mm) in diameter. Fruits are a three-lobed red capsule, and the seeds have red arils. Bursting heart is an understory shrub in eastern forests, with distinctive four-angled twigs and bright red fruit capsules A common ornamental, winter creeper is often found near old home sites and seeds. Burning bush and is especially widespread in midwestern and eastern states. (Native has pink capsules with red range adapted from USDA GRIN and selected references. Introduced seeds. Species of blueberry that range adapted from USDA PLANTS Database, Invasive Plant Atlas of the have large leaves can be distin- United States, and selected references.) guished by their alternate arrangement. The leaves of rusty blackhaw, a deciduous shrub or small tree native to the Southeast, are opposite and as long as 2–4 in. (5–10 cm). They are thick and shiny. The plant has a rusty-red pubescence on young stems and buds, clusters of creamy-white flowers, and purple or dark-blue fruit about 0.5 in. (1.3 cm) long. Coral honeysuckle is easily distinguished by its clusters of bright pink 2 in. (5 cm) tubular flowers and red berries. Several introduced species have similarities to winter creeper. Although leaves near the inflorescences of English ivy (see Vines, English Ivy) may resemble winter creeper leaves, all other leaves on English ivy are five-lobed with palmate veins. Oriental bittersweet (see Vines, Oriental Bittersweet), a deciduous shrub or trailing vine, has alternate 2–5 in. (5–12.5 cm) leaves. Its stems may be 2–4 in. (5–10 cm) in diameter. Although the arils on its seeds are red-orange, the mature fruit is green to yellow. Japanese honeysuckle (see

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A. This vine can create a dense ground cover. (James H. Miller, USDA Forest Service, Bugwood.org.) B. It can also climb by using aerial roots. (Chris Evans, River to River CWMA, Bugwood.org.) C. Inconspicuous flowers form in clusters from leaf axils. (James H. Miller, USDA Forest Service, Bugwood.org.) D. Each fruit contains one seed. (James H. Miller, USDA Forest Service, Bugwood.org.) E. Aerial roots grow from nodes on the stems. (James H. Miller, USDA Forest Service, Bugwood.org.)

Vines, Japanese Honeysuckle) lacks aerial roots and climbs by coiling its stems around the host plant. Its fragrant tubular flowers are white, tinged with pink. Introduction History. Winter creeper was brought to the United States in 1907 as a ground cover and ornamental. Two varieties are common in North America, Euonymus fortunei var. fortunei and E. fortunei var. radicans, and more than 50 cultivars, such as ‘Emerald’n Gold’ and ‘Gaity,’ are available in the horticultural trade. Cultivars vary by leaf size and color. Habitat. Winter creeper is most frequently found in old or abandoned homesites and near urban areas, where it escapes from gardens into adjoining forests. It may be in open grasslands, gravel pit debris, rocky bluffs, and floodplains, and along roads. Shade tolerant, it is quick to invade natural forest openings created by wind-throw, fire, or insect damage. It also invades human-disturbed sites. This vine commonly occurs with other invasives, such as multiflora rose (see Shrubs, Multiflora Rose) and oriental bittersweet. Winter creeper grows in a variety of environments, including full sun to dense shade and on fine- to coarse-textured soil. It prefers mesic sites, however, and is not found in heavy, wet soils or in wetlands. It grows in several types of forest communities, including those dominated by maples, oaks, elms, hickories, and pines. Although it can survive climates where the mean minimum temperature is as low as −30ºF (−34ºC), it requires protection from winter snow cover. It grows much better where minimum temperatures drop no lower than −20ºF (−29ºC). In China, winter creeper grows from near sea level to 11,200 ft. (3,400 m) elevation. Reproduction and Dispersal. Winter creeper reproduces both vegetatively and sexually. As a ground cover, independent plants grow from rootlets along the stems that rest on the ground. Lateral shoots grow from the main branches, and damage to the plant stimulates more lateral stems and more leaves to emerge from existing nodes. When plants are cut, sprouts develop from roots, root crowns, and cut stems. Conflicting accounts of whether or not winter creeper flowers is probably because only climbing plants with access to sufficient light produce flowers. Birds and wildlife that feed on the arils are responsible for long-distance dispersal of seeds. Both seeds and plant pieces can be transported by water to new sites. Little information is known concerning seed production, seed bank, viability, germination, or seedling establishment. Seedlings, however,

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are known to grow on disturbed or inhospitable sites, even through cracks in pavement. Growth rates vary with environmental conditions, such as sunlight, insect damage, water, and foliage damage by rabbits. Under the best conditions, plants need only one year to cover 75 percent of the ground with a dense mat of foliage. Impacts. Because winter creeper is tolerant of many environmental conditions and grows rapidly, it is a serious invader. Although some leaves do drop in spring, the plant is evergreen and begins growing sooner than native ephemerals in spring, thereby replacing them. It outcompetes native plants by depleting the soil of moisture and nutrients. As a ground cover, it forms a dense mat that eliminates understory plants by impeding seedling growth. By eliminating native ground-layer plants, it threatens native fauna, such as butterflies. As a climbing vine over taller shrubs and trees, especially those less than 20 ft. (6 m) tall, it blocks light and interferes with photosynthesis, weakening or killing the plants. Management. The best management is to prevent its establishment. Minimizing its use as a landscape plant and preventing fruit set will limit its ability to increase its range. Once established, the entire plant must be removed. Because winter creeper predominantly invades disturbed sites, maintenance of healthy communities and monitoring areas for signs of regrowth several times a year can keep the plant in check. Physical methods of control have limitations. Although labor intensive, small plants or small populations can be hand-pulled or dug out, especially in sensitive environments. All plant material, including roots and runners, must be removed, because any root pieces will sprout. Debris should be bagged and removed from the site. Cutting plants without using herbicides on the remaining rooted portion is ineffective because damage causes latent buds to sprout. Mowing, which is not practical in natural areas, is also ineffective without followup of treatment with a herbicide. Severing the climbing stems from the rest of the plant will prevent fruit development because only climbing stems flower. At a site in Kentucky, covering a monoculture stand of winter creeper with black plastic for a growing season suppressed its growth. The effectiveness of that method might be increased if the site were kept covered for two seasons. Burning selected plants with a blow torch may provide control when used in combination with other methods. Physical control must be combined with chemical applications. Foliar sprays of triclopyr ester or glyphosate can be applied from June through October, but must be repeated for several years. Use of a string trimmer on trailing plants to reduce growth and injure leaves will enhance the absorption of herbicide. Because glyphosate is nonselective, it should be used only where no native plants will be harmed. Triclopyr is selective only to broadleaf plants and can be used where grasses are intermixed with winter creeper. The best time for foliar sprays is late fall or early spring, when native vegetation is dormant. Where plants are well established or have climbed into tree canopies, application of herbicide to cut stems is effective, although it may have to be followed up with a foliar spray on resprouts. No effective biological control is yet known, but winter creeper is one of the major Asian invasive plants currently being studied in China for host-specific pests. It is susceptible to Asian Euonymus scale (Unaspis euonymi), which occurs with the plant in most of its U.S. range. By feeding on the leaves and causing them to drop, the scale damages tissue and reduces the plant’s photosynthesis capability. The scale can be lethal, especially to some cultivars, but it is also attacking native Euonymus species, such as burning bush and bursting heart, and also kills the rare subshrub Canby’s mountain-lover. Release in southern New England of five species of organisms from Asia in 1991–1995 provided no firm results. Plants are susceptible to attack by a fungal parasite, Texas root rot (Phymatotrichum omnivorum), which is endemic to the southwestern United States and adjacent Mexico.

644 n VINES The parasite’s presence may prevent the spread of winter creeper into that geographic area. Winter creeper is browsed by white-tailed deer in winter, and browsing by domestic goats or sheep is a possibility to keep plants small and prevent them from climbing and flowering.

Selected References Miller, James H. “Winter Creeper.” In Nonnative Invasive Plants of Southern Forests: A Field Guide for Identificaiton and Control. Gen. Tech. Rep. SRS-62. U.S. Department of Agriculture, Forest Service, Southern Research Station, 2003. http://www.invasive.org/eastern/srs/WC.html. Remaley, Tom. “Climbing Euonymus.” Weeds Gone Wild; Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2009. http://www.nps.gov/plants/alien/fact/ pdf/eufo1.pdf. Zouhar, Kris. “Euonymus fortunei.” Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, 2009. http:// www.fs.fed.us/database/feis/plants/vine/euofor/all.html.

n Wisteria Chinese Wisteria Also known as: Chinese-glysine Scientific name: Wisteria sinensis Synonyms: Kraunhia floribunda var. sinensis, K. sinensis, Rehsonia sinensis, Wisteria sinensis var. albiflora, Glysine sinensis Japanese Wisteria Also known as: No other names Scientific name: Wisteria floribunda Synonyms: Kraunhia floribunda, K. floribunda var alba, K. japonica, Millettia japonica, Rehsonia floribunda. Family: Pea (Fabaceae) Native Range. Chinese wisteria is from east- and south-central China. Japanese wisteria is native to Japan. Distribution in the United States. Both species are primarily in the southeastern and eastern states, from Texas east to Florida, north to Maine, and west to Michigan, Illinois, and Arkansas. Chinese wisteria is considered more invasive and is also in Hawai’i. Description. These two exotic wisterias are deciduous, woody perennial vines that climb trees and other structures. Because naturalized plants may be hybrids of the two, their characteristics are variable. The height of vines, which can reach 65 ft. (20 m), is limited only by the height of the object on which they climb. The vines have no tendrils or root hairs, but climb by twining their stems around host plants or structures. Stems may be slender to stout, with brown or white bark that may or may not be hairy. In old plants, stems can be 15 in. (38 cm) in diameter. Leaves are alternate and pinnately compound, varying in length, 4–16 in. (10– 40 cm) and in number of leaflets, 7–19. Chinese wisteria usually has fewer leaflets, 7–13. Leaflets, each 1.5–3 in. (4–8 cm) long, are oval to lance-shaped and have slightly wavy margins. Long hanging clusters of fragrant violet to purple flowers appear in spring, before the leaves fully develop. Individual flowers, supported by 0.6–0.8 in. (1.5–2 cm) pedicels, are typically pea-shaped and 0.5–1 in. (1.3–2.5 cm) long. Fruit is a velvety, fuzzy seed pod, either green or brown. The flattened pods are 4–7.5 in. (10–19 cm) long, narrowed at the

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base and with slight constrictions between the seeds. Pods, each containing 2–6 seeds, are retained on the vine after they mature. The flat, round seeds are 0.5 in. (1.3 cm) in diameter. Although most naturalized wisteria plants, at least in the southeastern United States, may be considered hybrids, the original two species are distinguishable by several characteristics. Chinese wisteria vines twist clockwise, from lower left to upper right, while Japanese wisteria twists counterclockwise, from lower right to upper Japanese wisteria and Chinese wisteria are distinct in their native ranges left. Chinese wisteria has dark- but hybridize in the United States. (Native range adapted from USDA gray bark and hairy stems. GRIN and selected references.) Japanese wisteria usually has white or chalky-gray bark, and only the young stems are hairy. The flower clusters, called racemes, on Chinese wisteria are shorter, 4–20 in. (10–50 cm) long, and the flowers in the cluster all open together. Japanese wisteria racemes can be very long, 1–3 ft. (0.3–0.9 m), and the flowers open sequentially from the base to the tip of the raceme. Related or Similar Species. American wisteria, also called Atlantic wisteria, is native to the southeastern U.S. coastal plain from Virginia south to Florida and west to eastern Texas. It can be found climbing over shrubs and fences in moist thickets adjacent to water bodies. Like the exotic wisterias, it can climb 50 ft. (15 m). The brown to reddish-brown stems are hairless, and the vines twine clockwise. Leaves are usually 12 in. (30 cm) long, with 9–15 leaflets, each 1–3 in. (2–8 cm). The lower leaf surface is a milky green color. Purplish-blue flowers occur in May, after the plant has leafed out. Flower clusters are shorter than those of either Chinese wisteria or Japanese wisteria, 1.5–6 in. (4–15 cm) long, and pedicels are 0.2–0.4 in. (0.5–1 cm) long. The most distinct feature is that the 2–4 in. (5–10 cm) brown seedpods are not hairy, but glabrous. Several cultivars, such as ‘Nivea’ with white flowers, ‘Magnifica’ with purple-blue flowers, and a yellow blotch, have been developed from American wisteria. American wisteria is host for many butterflies and bees. Trumpet creeper, native to the central and eastern United States, is distinguished from wisterias by its opposite leaves with toothed margins and its orange-red flowers, which bloom from late spring into autumn. Introduction History. Both exotic wisterias were imported for ornamental use, Chinese wisteria from China in 1816, and Japanese wisteria from Japan around 1830. Both species are used extensively in the southeastern states to decorate porches, gazebos, and garden walls. Because of its vigorous growth, wisteria escaped landscape plantings. Although Chinese wisteria and Japanese wisteria were imported as two distinct species, recent evidence indicates that naturalized and invasive plants are hybrids between the two. It is believed that the hybrids were propagated and spread through the nursery trade. Both species and several cultivars, with white, purple, pink, or lavender flowers, continue to be sold as popular ornamentals.

646 n VINES Habitat. Exotic wisterias are common in right-of-ways, roadsides, forest edges, ditches, and in riparian zones. Plants also invade open or disturbed areas after burns or clearing. Although they can be found in part shade, plants grow best in full sun. They tolerate a variety of soils and moisture, but prefer deep loamy soils that are well drained. Reproduction and Dispersal. Reproduction is primarily vegetative. Nodes on stolons, which creep along the ground surface, sprout new plants. Plants spread locally from homesites into surrounding woodlands, from neglected gardens or due to improper disposal of garden waste. Seeds are produced under favorable conditions, and can be carried long distances downstream by water to new riparian sites. Long-distance dispersal is accomplished through Internet and nursery sales. The reproductive biology of the hybrids, how seeds form and disperse to new locaBoth alien wisteria species, as well as their hybrids, are invasive, especially tions, is not yet known. Impacts. Aggressive wisteria in the southern and eastern states. (Introduced range adapted from USDA PLANTS Database, Invasive Plant Atlas of the United States, and selected plants are hardy and can live references.) for 50 or more years. New vines, either from seeds or from root sprouts, that trail on the ground can form thickets that exclude all other plants. Stems climb onto and over native shrubs and trees, either shading them out or strangling them. The twining vines circle the host tree tightly, cutting through the bark and girdling and killing them. When trees die, the forest canopy is altered, creating sunny openings that may initially encourage growth of native species, but ultimately favor the expansion of wisteria. Seeds and pods of Chinese wisteria are toxic, causing nausea, vomiting, stomach pain, or diarrhea if eaten. Management. Because wisteria will invade disturbed areas, it is important to maintain healthy ecosystems. Physical control is practical on small plants or small infestations. Small plants can be dug up in sensitive sites where herbicides are prohibited. Vines with seed pods should be bagged and disposed of properly, but piles of pulled material can remain on site as long as the area is monitored frequently for regrowth. Vines that grow into

WISTERIA n 647

A. Vines climb by twining around other plants, girdling and killing them. (Chris Evans, River to River CWMA, Bugwood.org.) B. Long compound leaves have many leaflets. (James H. Miller, USDA Forest Service, Bugwood.org.) C. Pendulant clusters of showy flowers may cover the plant. (Chris Evans, River to River CWMA, Bugwood.org). D. Fuzzy seed pods each contain 2–6 seeds. (Ted Bodner, Southern Weed Science Society, Bugwood.org.)

trees can be severed at the base, close to the root crown. Cut resprouts as they occur, every two weeks during the growing season. Cutting vines repeatedly to ground level slows growth, prevents seed production, and decreases nutrient reserves. Chemical control is effective, either sprayed on foliage or applied to basal bark or cut stems. Foliar sprays work best when applied to resprouts after vines have been cut. Spraying is efficient for large stands that cover all other vegetation. Foliar application is also best where cutting the stumps or physical removal is too disruptive. Applications of herbicide to cut stumps are appropriate for large stands where thick vines are well established. If applied with care, systemics such as glyphosate or triclopyr can be used without harming nontarget plants. In order to ensure protection of native species, spraying should be done before or after the spring bloom of wildflowers, either early in spring or in the fall. Because triclopyr is selective to broadleaf plants, it is safe to apply around native grasses. Chlopyralid is a herbicide specifically targeted to the sunflower, buckwheat, and pea families, but it seeps into groundwater. Picloram can be used where no desirable vegetation remains. No biological control for wisteria is known.

Selected References “Exotic Wisterias.” Weed of the Week. USDA Forest Service, Invasive Plants, 2006. http://na.fs.fed.us/ fhp/invasive_plants. Swearingen, J., and Tom Remaley. “Chinese Wisteria.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2010. http://www.nps .gov/plants/alien/fact/pdf/wisi1.pdf. Swearingen, J., and Tom Remaley. “Japanese Wisteria.” Weeds Gone Wild: Alien Plant Invaders of Natural Areas. Plant Conservation Alliance’s Alien Plant Working Group, 2010. http://www.nps .gov/plants/alien/fact/pdf/wifl1.pdf. Trusty, J. L., B. G. Lockaby, W. C. Zipperer, and L. R. Goertzen. “Identity of Naturalised Exotic Wisteria (Fabaceae) in the South-Eastern United States.” Weed Research 47: 479–87, 2007. http:// www.srs.fs.usda.gov/pubs/ja/ja_trusty003.pdf.

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Tables and Lists about Invasive Plants

n Common Names and Scientific Names All invasive plant species profiled in the 80 entries of Volume 2 show their common and scientific names in the entry headings for these plants. Below are common and scientific names of other species discussed within the entries of Volume 2. Common Name

Scientific Name

Aquatic Anchored waterhyacinth

Eichhornia azurea

Brazilian waterhyacinth

Eichhornia paniculata

Brazilian waterweed, Brazilian elodea

Egeria densa

Canadian waterweed

Elodea canadensis

Common salvinia, water spangles

Salvinia minima

Coon’s tail, common hortwort

Ceratophyllum demersum

Devil pod, bat nut, horn nut

Trapa bicornis

Duckweed

Lemna spp.

Northern watermilfoil, shortspike watermilfoil

Myriophyllum sibiricum

Mexican waterfern

Azolla mexicana

Mosquito fern

Azolla caroliniana

Pacific mosquito fern

Azolla filiculoides

Parrotfeather

Myriophyllum aquaticum

Pickerelweed

Pontederia cordata

Pondweed

Potamogeton spp.

Tapegrass

Vallisneria americana

Variable leaf waterhyacinth

Eichhornia diversifolia

Variable watermilfoil

Myriophyllum heterophyllum (Continued )

650 n COMMON NAMES AND SCIENTIFIC NAMES Common Name

Scientific Name

Water clover

Marsilea vestilia

Forbs Arrowhead

Sagittaria spp.

Bagpod, bladderpod

Sesbania vesicaria

Barbwire Russian thistle

Salsola paulsenii

Beach layia

Layia carnosa

Blazing star

Liatris spp.

Bloodroot

Sanguinaria canadensis

Bohemian knotweed

Polygonum × bohemicum (P. cuspidatum × P. sachalinense)

Branched tearthumb

Polygonum meisneranum

Broomleaf toadflax

Linaria genistifolia

Buffalobur nightshade

Solanum rostratum

Bull thistle

Cirsium vulgare

Burning bush, kochia, summer-cypress

Bassia scoparia

Canada germander

Teucrium canadense

Canada toadflax, blue toadflax

Nuttallanthus canadensis

Caper spurge, gopher plant

Euphorbia lathyris

Carolina horsenettle

Solanum carolinense

Celandine

Chelidonium majus

Celandine poppy

Stylophorum diphyllum

Clasping pepperweed

Lepidium perfoliatum

Coastal sand spurge

Euphorbia exserta

Common parsnip, cow parsnip

Heracleum maximum

Crinkleroot, twoleaf toothwort

Cardamine diphylla

Cutleaf toothwort

Cardamine laciniata

Cypress spurge

Euphorbia cyparissias

Diffuse knapweed

Centaurea diffusa

Dutchman’s breeches

Dicentra cucullaria

Dwarf St. Johnswort

Hypericum mutilum

Early saxifrage

Saxifraga virginica

Eggleaf spurge

Euphorbia oblongata

COMMON NAMES AND SCIENTIFIC NAMES n 651 Common Name

Scientific Name

Fireweed

Epilobium angustifolium

Fringecup

Tellima grandiflora

Geraldton carnation weed

Euphorbia terracina

Giant knotweed

Polygonum sachalinense

Giant wild pine, giant air plant

Tillandsia utriculata

Globe artichoke

Cynara scolymus

Green comet milkweed

Asclepias viridiflora

Ground ivy

Glechoma hederaceae

Hairy vetch

Vicia villosa

Hairy whitetop

Cardaria pubescens

Harbinger-of-spring

Erigenia bulbosa

Hart’s tongue fern

Asplenium scolopendrium

Heartleaf horsenettle

Solanum cardiophyllum

Hepatica

Hepatica nobilis

Horsetail

Equisetum spp.

Humboldt Bay owl’s clover

Castilleja ambigua ssp. humboldtiensis

Iberian knapweed, Iberian starthistle

Centaurea iberica

Italian thistle

Carduus pycnocephalus

Jesup’s milkvetch

Astralagus robbinsii var. Jesupi

Large St. Johnswort

Hypericum majus

Lens-pod hoary cress

Cardaria chalepensis

Madwoman’s milk, sun spurge

Euphorbia helioscopia

Malta starthistle

Centaurea melitensis

Marsh jaumea

Jaumea carnosa

Marsh marigold

Caltha palustris

Milk thistle

Silybum marianum

Moth mullein

Verbascum blattaria

Oppositeleaf Russian thistle

Salsola soda

Partridge pea

Chamaecrista fasciculata

Pickleweed

Salicornia virginica

Piggyback plant

Talmiea menziesii

Pink sand verbena

Abronia umbellata ssp. breviflora (Continued )

652 n COMMON NAMES AND SCIENTIFIC NAMES Common Name

Scientific Name

Plumeless thistle

Carduus acanthoides

Pt. Reyes bird’s beak

Cordylanthus maritimus var. palustris

Poison hemlock

Conium maculatum

Prostrate ticktrefoil, dollar leaf plant

Desmodium rotundifolium

Purple starthistle, red starthistle

Centaurea calcitrapa

Purplestem angelica

Angelica atropurpura

Queen Anne’s lace

Daucus carota

Red clover

Trifolium pretense

Rio Grande ragweed, South Texas ambrosia

Ambrosia cheiranthifolia

Russian knapweed

Acroptilon repens

Sacramento Mountain thistle

Cirsium vinaceum

Safflower

Carthamus tinctorius

Sand dune thistle

Cirsium pitcheri

Scotch thistle

Onopordum acanthium

Seabeach amaranth

Amaranthus pumilus

Seabeach evening primrose

Oenothera humifusa

Seacoast marsh elder

Iva imbricata

Sea fig

Carpobrotus chilensis

Searocket

Cakile edentula

Sea sandwort

Honckenya peploides

Seaside goldenrod

Solidago sempervirens

Seaside knotweed

Polygonum glaucum

Sicilian starthistle

Centaurea sulphurea

Slender-flowered thistle

Carduus tenuflorus

Slender lespedeza

Lespedeza virginica

Slender purslane

Sesuvium maritimum

Slender Russian thistle

Salsola collina

Spring beauty

Claytonia virginica

Squarrose knapweed

Centaurea virgata ssp. squarrosa

Squirrel-corn

Dicentra canadensis

Swamp verbena

Verbena hastata

COMMON NAMES AND SCIENTIFIC NAMES n 653 Common Name

Scientific Name

Sweet cicily

Osmorhiza claytonii

Tinker’s penny

Hypericum anagalloides

Toothed spurge

Euphorbia serrata

Toothworts

Cardamine spp.

Tree ferns

Cibotium spp.

Trillium

Trillium spp.

Tropical curlygrass fern, ray fern

Actinostachys pennula

Trout lily

Erythronium spp.

Twinleaf

Jeffersonia diphylla

Violet

Viola spp.

Virginia bluebells

Mertensia virginica

Wavyleaf thistle

Cirsium undulatum

Western horsenettle, Torrey’s nightshade

Solanum dimidiatum

White avens

Geum canadense

White ginger

Hedychium coronarium

Wild ginger

Aserium canadense

Wild parsnip

Pastinaca sativa

Wolf’s primrose

Oenothera wolfii

Yellow ginger

Hedychium flavescens

Yellowspine thistle

Cirsium ochrocentrum

Zapata bladderpod

Lesquerella thamnophila

Graminoids African feathergrass

Pennisetum macrourum

Alpine hairgrass

Deschampsia nubigena

American beach grass

Ammophila breviligulata

American cupscale

Sacciolepis striata

Arizona cottontop

Digitaria californica

Arizona wheatgrass

Elymus arizonicus

Bahia grass

Paspalum notatum

Bald brome

Bromus racemosus

Barley

Hordeum spp.

Beach panic grass

Panicum amarum (Continued )

654 n COMMON NAMES AND SCIENTIFIC NAMES Common Name

Scientific Name

Beachstar

Remirea maritima

Beardless wheatgrass

Pseudoroegneria spicata

Bermuda grass

Cynodon dactylon

Blue bunchgrass

Pseudoroegneria spicata

Bluebunch wheatgrass

Pseudoroegneria spicata

Brazilian satintail

Imperata brasiliensis

Broadleaf cattail

Typha latifolia

Bulb panicgrass

Panicum bulbosum

Bulrush

Scirpus spp.

Bush muhly

Muhlenbergia porteri

California cordgrass

Spartina foliosa

California satintail

Imperata brevifolia

Cattail

Typha spp.

Coast cockspur

Echinochloa walteri

Columbia needlegrass

Achnatherum nelsonii

Cosmopolitan bulrush

Schoenoplectus maritimus

Crested wheatgrass

Agropyron cristatum

Dune panic grass

Panicum amarulum

Elephant grass

Pennisetum purpureum

Feathertop

Pennisetum villosum

Field brome, Japanese brome

Bromus arvensus

Foxtail

Alopecuris spp.

Galleta grass

Pleuraphis spp.

Hairy wheatgrass

Thinopyrum intermedium

Indian ricegrass

Achnatherum hymenoides

Intermediate wheatgrass

Thinopyrum intermedium

Japanese blood grass

Imperata cylindrica ‘Rubra’

Japanese brome

Bromus japonicus

Jointed grass

Arthraxon hispidus

Kyasuma grass

Pennisetum pedicellatum

Large-headed sedge

Carex macrocephala

Maidencane

Panicum hemitomon

COMMON NAMES AND SCIENTIFIC NAMES n 655 Common Name

Scientific Name

Missiongrass, feathery pennisetum

Pennisetum polystachyon

Needle and thread grass

Hesperostipa comata

Needlegrass

Stipa spp.

Northern reedgrass

Calamagrostis stricta

Northern wheatgrass

Elymus lanceolatus

Pearl millet

Pennisetum glaucum

Pili grass, tanglehead

Heteropogon contortus

Plains bristlegrass

Setaria macrostachya

Reedgrass

Calamagrostis stricta

Rush wheatgrass

Thinopyrum ponticum

Russian wheatgrass

Thinopyrum junceiforme

Ryebrome

Bromus secalinus

Ryegrass

Lolium multiflorum

St. Augustine grass

Stenotaphrum secundatum

Saltgrass

Distichlis spicata

Sandberg bluegrass

Poa secunda

Sawgrass

Cladium jamaicense

Sea oats

Uniola paniculata

Seaside arrowgrass

Triglochin maritima

Sedge

Carex spp., Cyperus spp.

Silverberry

Elaeagnus commutata

Sheep fescue

Festuca ovina

Small cordgrass

Spartina maritima

Smooth brome

Bromus inermis

Soft brome

Bromus hordeaceus

Sorghum, shattercane

Sorghum bicolor

Squirreltail

Elymus elymoides

Sudangrass

Sorghum bicolor spp. drummondii

Tall wheatgrass

Thinopyrum elongatum

Thurber’s needlegrass

Achnatherum thurberianum

Tick quackgrass

Thinopyrum pungens

Toe toe, Richard’s pampas grass

Cortaderia richardii (Continued )

656 n COMMON NAMES AND SCIENTIFIC NAMES Common Name

Scientific Name

Virginia cutgrass

Leersia virginica

Western wheatgrass

Agropyron smithii

Wheatgrass

Agropyron spp.

White cattail

Typha glauca

Wild rye

Elymus spp.

Shrubs Akalakala

Rubus macraei

Allegheny blackberry

Rubus allegheniensis

American barberry

Berberis canadensis

Antelope bitterbrush

Purshia tridentata

Bearberry honeysuckle, twinberry honeysuckle

Lonicera involucrata

Big sagebrush

Artemisia tridentata

Blueberry

Vaccinium spp.

Bridal broom

Retama monosperma

Bristletips

Oxyspora paniculata

Buffaloberry

Shepherdia argentia

Burning bush

Euonymus atropurpurea

Bursage

Ambrosia spp.

Bursting heart

Euonymus americanus

Canadian honeysuckle

Lonicera canadensis

Canary Island St. Johnswort

Hypericum canariense

Canby’s mountain-lover

Paxistima canbyi

Cane ti, cane tibouchina

Tibouchina herbacea

Cherokee rose

Rosa laevigata

Climbing prairie rose

Rosa setigera

Cockroach berry

Solanum capsicoides

Coffee colubrina

Colubrina arborescens

Common barberry

Berberis vulgaris

Common elderberry

Sambucus canadensis

Coralberry

Symphoricarpos orbiculatus

Creosote bush

Larrea tridentata

COMMON NAMES AND SCIENTIFIC NAMES n 657 Common Name

Scientific Name

Crimson bottlebrush

Callistemon citrinus

Cuban nakedwood

Colubrina cubensis

Dog rose

Rosa canina

Drummond rattlebox

Sesbania drummondii

Dwarf gorse

Ulex minor

European fly honeysuckle, dwarf honeysuckle

Lonicera xylosteum

European wand loosestrife

Lythrum virgatum

Georgia bully

Sideoxylon thornei

Glorybush, princess flower

Tibouchina urvilleana

Grape honeysuckle

Lonicera reticulata

Greasewood

Sarcobatus vermiculatus

Hawaiian blackberry, akala

Rubus hawaiiensis

Himalayan blackberry

Rubus armeniacus

Maccartney rose

Rosa bracteata

Pasture rose

Rosa carolina

Pineland verbena, depressed shrubverbena

Lantana depressa

Prickly rose

Rosa acicularis

Privet

Ligustrum spp.

Purple African nightshade

Solanum marginatum

Purpleflowering raspberry

Rubus odoratus

Red honeysuckle

Lonicera dioica

Rugosa rose

Rosa rugosa

Running strawberry bush

Euonymus obovatus

Rusty blackhaw

Viburnum rufidulum

Saltbush

Atriplex spp.

Sawtooth blackberry

Rubus argutus

Shadscale saltbush

Atriplex confertifolia

Shrubby nightshade

Solanum robustum

Shrubby Russian thistle

Salsola vermiculata

Silverleaf nightshade

Solanum elaeagnifolium

Silversword

Argyroxiphium sandwicense ssp. sandwicense (Continued )

658 n COMMON NAMES AND SCIENTIFIC NAMES Common Name

Scientific Name

Silverthorn

Elaeagnus pungens

Smooth rose

Rosa blanda

Snowpeaks raspberry

Rubus niveus

Soldierwood

Colubrina elliptica

Southern bush honeysuckle

Diervilla sessilifolia

Staghorn sumac

Rhus typhina

Swamp fly honeysuckle

Lonicera oblongifolia

Swamp rose

Rosa palustris

Sweetberry honeysuckle

Lonicera caerulea

Sweetbriar rose

Rosa eglanteria

Turkey berry

Solanum torvum

Virginia rose

Rosa virginiana

West Indian raspberry

Rubus rosifolius

Winter honeysuckle, fragrant honeysuckle

Lonicera fragrantissima

Woods’ rose

Rosa woodsii

Wormwood

Artemisia spp.

Yellow honeysuckle

Lonicera flava

Trees Alder

Alnus spp.

Ash

Fraxinus spp.

Aspen

Populus spp.

Athel tamarisk

Tamarisk aphylla

Australian river oak

Casuarina cunninghamiana

Autumn olive

Elaeagnus umbellata

Bald cypress

Taxodium distichum

Bay cedar

Suriana maritima

Beech

Fagus spp.

Birch

Betula spp.

Brazilian oak

Casuarina glauca

Buttonwood

Conocarpus erectus

Columnar cactus

Cereus spp.

COMMON NAMES AND SCIENTIFIC NAMES n 659 Common Name

Scientific Name

California buckeye

Aesculus californica

California live oak

Quercus agrifolia

Catalpa

Catalpa speciosa

Common guava

Psidium guajava

Cottonwood

Populus spp.

Crape myrtle

Lagerstroemia indica

Elm

Ulmus spp.

Elongata princess tree

Paulownia elongata

Florida thatch palm

Thrinax radiata

Honeylocust

Gleditsia triacanthos

Koa

Acacia koa

Linden

Tilia spp.

Live oak

Quercus virginiana

Machineel

Hippomane mancinella

Mamane

Sophora chrysophylla

Maple

Acer spp.

Mesquite

Prosopis spp.

Oak

Quercus spp.

Ohia

Metrosideros polymorpha

Peruvian peppertree

Schinus molle

Purple osier willow

Salix purpurea

Red mulberry

Morus rubra

Sassafras

Sassafras albidum

Spruce

Picea spp.

Surinam cherry

Eugenia uniflora

Texas umbrella chinaberry

Melia azedarach cv ‘Umbraculiformis’

Wax myrtle

Myrica cerifera

West Indian mahogany

Swietenia mahagoni

White basswood

Tilia heterophylla

White-flowered paulownia

Paulownia fortunei

White mulberry

Morus alba

Wild cinnamon

Canella winterana (Continued )

660 n COMMON NAMES AND SCIENTIFIC NAMES Common Name

Scientific Name

Willow

Salix spp.

Woman’s tongue

Albizia lebbeck

Vines Alfalfa dodder

Cuscuta approximata

Amberique bean, American trailing wild bean

Strophostyles helvula

American bittersweet

Celastrus scandens

American climbing fern

Lygodium palmatum

American hogpeanut

Amphicarpaea bracteata

American wisteria, Atlantic wisteria

Wisteria frutescens

Atlantic Ivy, Irish ivy

Hedera hibernica

Beach clustervine

Jacquemontia reclinata

Black pepper

Piper nigrum

Boston ivy

Parthenocissus tricuspidata

Bur cucumber

Sicyos angulatus

Chinese honeysuckle

Lonicera japonica var. chinensis

Chinese yam, air potato

Dioscorea bulbifera

Cinammon vine, Chinese yam

Dioscorea oppositifolia

Climbing nightshade

Solanum dulcamara

Colchis ivy, Persian ivy

Hedera colchica

Common dodder, scaldweed, swamp dodder

Cuscuta gronovii

Common hops

Humulus lupulus

Coral honeysuckle

Lonicera sempervirens

Dutchman’s pipe

Aristolochia macrophylla

Grape

Vitis spp.

Hall’s honeysuckle

Lonicera japonica var. halliana

Heartleaf peppervine

Ampelopsis cordata

Hedge false bindweed

Calystegia sepium

Honeyvine

Cyanchum laeve

Hollyhock bindweed

Convolvulvus althaeoides

Hybrid akebia

Akebia x pentaphylla

Littleleaf sensitive-briar

Mimosa microphylla

COMMON NAMES AND SCIENTIFIC NAMES n 661 Common Name

Scientific Name

Mallow bindweed

Convolvulus althaeoides

Morning glories

Ipomoea spp.

Orangeberry nightshade

Solanum lanceolatum

Peppervine

Ampelopsis arborea

Pipevine

Aristolochia macrophylla

Poison ivy

Toxicodendron radicans

Three-leaf akebia

Akebia trifoliata

Trumpet creeper

Campsis radicans

Virginia creeper

Parthenocissus quinquefolia

Western morning glory

Calystegia occidentalis

Wetlands nightshade

Solanum tampicense

White swallow-wort

Cynanchum vincetoxicum

Wild cucumber

Echinocystis lobata

Wild grape

Vitis spp.

Woolly Dutchman’s pipe

Aristolochia tomentosa

Epiphytes Bromeliads

Tillandsia spp.

Orchids

Encyclia bootheriana, Oncidum luridum

Birds American Robin

Turdus migratorius

Black-capped Chickadee

Poecile atricapillus

Black Skimmer

Rynchops niger

Blue Jay

Cyanocitta cristata

Bobwhite Quail

Colinus virginianus

California Clapper rail

Rallus longirostris obsoletus

Cedar Waxwing

Bombycilla cedrorum

Chinese Turtledove

Streptopelia chinensis

Chukar Partridge

Alectoris chukar

Common Myna

Acridotheros tristis

Everglades Snail Kite

Rostrhamus sociabilis

Fish Crow

Corvus ossifragus

Gambel’s Quail

Lophortyx gambelii (Continued )

662 n COMMON NAMES AND SCIENTIFIC NAMES Common Name

Scientific Name

Golden Eagle

Aquila chrysaetos

Grasshopper Sparrow

Ammodramus savannarum

Greater Prairie Chicken

Tympanuchus cupido

Hawaiian Coot

Fulica alai

Hawaiian Gallinule

Gallinule chloropus

Hawaiian Stilt

Himantopus mexicanus knudseni

Japanese White-eye

Zosterops japonica

Least Bell’s Vireo

Vireo bellii pusillus

Least Tern

Sterna antillarum

Meadowlark

Stumella spp.

Mockingbird

Mimus polyglottos

Palila

Loxioides bailleui

Pheasant

Phasianus colchicus

Piping Plover

Charadrius melodus

Red-billed Leiothrix

Leiothrix lutea

Red-winged Blackbird

Agelaius phoeniceus

Ruffed Grouse

Bonasa umbellus

Scaled Quail

Callipepla squamata

Southwestern Willow Flycatcher

Empidonax traillii extimus

Starling

Sturnus vulgaris

Wild Turkey

Meleagris gallopavo

Wood Stork

Mycteria americana

Mammals Cotton mouse

Peromyscus gossypinus

Cotton rats

Sigmodon spp.

Coyote

Canis latrans

Deer mice

Peromyscus maniculatus

Elk

Cervus canadensis

Ground squirrels

Citellus spp.

Feral pig

Sus scrofa

Hispid cotton rat

Sigmodon hispidus

Marsh rice rat

Oryzomys palustris

COMMON NAMES AND SCIENTIFIC NAMES n 663 Common Name

Scientific Name

Mongoose

Herpestes auropunctatus

Mule deer

Odocoileus hemionus

Salt marsh harvest mouse

Reithrodontomys raviventris

White-tailed deer

Odocoileus virginianus

Woodrats

Neotoma spp.

Fish Chain pickerel

Esox niger

Chum salmon

Oncorhynchus keta

English sole

Pleuronectes vetulus

Grass carp

Ctenopharyngodon idella

Reptiles and Amphibians American alligator

Alligator mississippiensis

American crocodile

Crocodylus acutus

Gopher snake

Pituophis spp.

Gopher tortoise

Gopherus polyphemus

Green sea turtle

Chelonia mydas

Green tree frog

Hyla cinerea

Indigo snake

Drymarchon corais couperi

Leopard frog

Rana spp.

Loggerhead turtle

Caretta caretta ssp. caretta

Pig frog

Rana grylio

Invertebraes Caribbean fruit fly

Anastrepha suspensa

Colorado potato beetle

Leptinotarsa decemlineata

Garden white butterflies

Pieris spp.

Green peach aphid

Myzus persicae

Gypsy moth

Lymantria dispar

Honey bee

Apis mellifera

Monarch butterfly

Danaus plexippus

Mullein leaf bug

Campylomna verbasci

Northeastern sea beach tiger beetle

Cicindela dorsalis dorsalis

Pearly eye butterfly

Enodia anthedon (Continued )

664 n COMMON NAMES AND SCIENTIFIC NAMES Common Name

Scientific Name

Silverleaf whitefly

Bemisia argentifolii

Soybean loper

Pseudoplusia includens

Sugar beet leafhopper

Circulifer tenellus

Tobacco budworm

Helicoverpa virescens

Tobacco hornworm

Manduca sexta

Tomato hornworm

Manduca quinquemaculata

Tomato pinworm

Keiferia lycopersicella

West Virginia white butterfly

Pieris virginiensis

Crustaceans Dungeness crab

Cancer magister

Oyster

Crassotrea gigas

n State-by-State Designations of Invasive or Noxious Weeds

The following states have officially declared certain plants (discussed or mentioned in this encyclopedia) to be noxious, invasive, or undesirable on some level. Lack of an entry for a state, however, should not be interpreted as lack of a problem. Some plants may be noxious, invasive, or undesirable even without official recognition. States have differing levels of organization for identifying noxious or unwanted plants. Alabama Aquatic: Anchored waterhyacinth, Eurasian watermilfoil, giant salvinia, hydrilla, parrotfeather, water chestnut, waterhyacinth Forbs: Garlic mustard, giant hogweed, Japanese knotweed, purple loosestrife Graminoids: African feathergrass, Brazilian satintail, cogongrass, common reed, Japanese stilt grass, kikuyugrass, kyasuma grass, mission grass Shrubs: Multiflora rose, shrubby Russian thistle, tropical soda apple, turkey berry. Trees: Melaleuca Vines: Dodders, Japanese climbing fern, Old World climbing fern, mile-a-minute, wetlands nightshade Alaska Forbs: Canada thistle, Carolina horsenettle, hairy whitetop, leafy spurge, perennial pepperweed, Russian knapweed Graminoids: Quackgrass Vines: Field bindweed Arizona Aquatic: Anchored waterhyacinth, giant salvinia, hydrilla, water chestnut, waterhyacinth Forbs: Canada thistle, Carolina horsenettle, Dalmatian toadflax, diffuse knapweed, dyer’s woad, hairy whitetop, halogeton, Iberian knapweed, leafy spurge, lens-pod cress, plumeless thistle, purple loosestrife, purple starthistle, Russian knapweed, Scotch thistle, Sicilian starthistle, spotted knapweed, squarrose knapweed, yellow starthistle Graminoids: Buffelgrass, quackgrass Shrubs: Tropical soda apple Vines: Dodders, field bindweed Arkansas Forbs: Barbwire Russian thistle, bull thistle, Carduus spp. thistles, Carolina horsenettle, Cirsium spp. thistles, hemp sesbania, Italian thistle, oppositeleaf Russian thistle, plumeless thistle, prickly Russian thistle, purple loosestrife, Scotch thistle, slender Russian thistle Graminoids: Bald brome, ryebrome Shrubs: Shrubby Russian thistle, silverleaf nightshade Vines: Dodders, field bindweed (Continued )

666 n STATE-BY-STATE DESIGNATIONS OF INVASIVE OR NOXIOUS WEEDS California Aquatic: Anchored waterhyacinth, giant salvinia, hydrilla, water chestnut, waterhyacinth Forbs: Barbwire Russian thistle, Canada thistle, Carolina horsenettle, common St. Johnswort, Dalmatian toadflax, diffuse knapweed, dyer’s woad, giant hogweed, giant knotweed, hairy whitetop, halogeton, Iberian knapweed, Italian thistle, Japanese knotweed, leafy spurge, lens-pod cress, musk thistle, perennial pepperweed, plumeless thistle, prickly Russian thistle, purple loosestrife, purple starthistle, Russian knapweed, Scotch thistle, Sicilian starthistle, slender Russian thistle, spotted knapweed, squarrose knapweed, western horsenettle, yellow starthistle Graminoids: African feathergrass, Brazilian satintail, California satintail, cogongrass, kikuyugrass, kyasuma grass, medusahead, mission grass, quackgrass Shrubs: French broom, gorse, Scotch broom, shrubby Russian thistle, silverleaf nightshade, tropical soda apple, turkey berry Trees: Melaleuca Vines: Dodders, field bindweed, wetlands nightshade Colorado Aquatic: Eurasian watermilfoil, giant salvinia, hydrilla Forbs: Bull thistle, Canada thistle, Chinese lespedeza, common mullein, common St. Johnswort, Dalmatian toadflax, diffuse knapweed, dyer’s woad, halogeton, leafy spurge, moth mullein, musk thistle, perennial pepperweed, plumeless thistle, purple loosestrife, Russian knapweed, Scotch thistle, spotted knapweed, squarrose knapweed, yellow starthistle Graminoids: Cheatgrass, medusahead, quackgrass Trees: Russian olive, tamarisk Vines: Field bindweed Connecticut Aquatic: Eurasian watermilfoil, giant salvinia, hydrilla, parrotfeather, variable watermilfoil, water chestnut, waterhyacinth Forbs: Burning bush, Canada thistle, fig buttercup, garlic mustard, giant hogweed, giant knotweed, goutweed, Japanese knotweed, leafy spurge, perennial pepperweed, purple loosestrife, Scotch thistle, spotted knapweed Graminoids: Asiatic sand sedge, cheatgrass, common reed, Japanese stilt grass Shrubs: Amur honeysuckle, Bell’s honeysuckle, common barberry, Japanese barberry, Morrow’s honeysuckle, multiflora rose, Tatarian honeysuckle Trees: Autumn olive, princess tree, Russian olive, tree of heaven Vines: Black swallow-wort, Japanese honeysuckle, Japanese hops, kudzu, mile-a-minute, Oriental bittersweet, pale swallow-wort, porcelainberry Delaware Forbs: Canada thistle Florida Aquatic: Anchored waterhyacinth, common salvinia, Eurasian watermilfoil, hydrilla, water chestnut, waterhyacinth Forbs: Giant hogweed, purple loosestrife Graminoids: African feathergrass, Brazilian satintail, cogongrass, kikuyugrass, kyasuma grass, mission grass Shrubs: Asiatic colubrina, shrubby Russian thistle, tropical soda apple, turkey berry Trees: Australian pine, Brazilian peppertree, carrotwood, fire tree, melaleuca

STATE-BY-STATE DESIGNATIONS OF INVASIVE OR NOXIOUS WEEDS n 667 Vines: Dodders, field bindweed, Japanese climbing fern, kudzu, Old World climbing fern, wetlands nightshade Hawai’i Forbs: Canada thistle, Carolina horsenettle, common mullein, hairy whitetop, halogeton, leafy spurge, perennial pepperweed, prickly Russian thistle, Russian knapweed Graminoids: Cogongrass, crimson fountain grass, jubata grass, quackgrass Shrubs: French broom, Gorse, Koster’s curse, sawtooth blackberry, Scotch broom, silverleaf nightshade, snowpeaks raspberry, Spanish broom, turkey berry, yellow Himalayan raspberry Trees: Fire tree, velvet tree Vines: Field bindweed Idaho Aquatic: Eurasian watermilfoil Forbs: Buffalobur nightshade, Canada thistle, Dalmatian toadflax, diffuse knapweed, dyer’s woad, leafy spurge, musk thistle, perennial pepperweed, plumeless thistle, purple loosestrife, Russian knapweed, Scotch thistle, spotted knapweed, yellow starthistle, yellow toadflax Shrubs: Scotch broom, silverleaf nightshade Vines: Field bindweed Illinois Forbs: Canada thistle, musk thistle Vines: Kudzu Indiana Forbs: Canada thistle, purple loosestrife Graminoids: Sorghum, Sudangrass Shrubs: Multiflora rose Iowa Forbs: Bull thistle, Canada thistle, Carduus spp., Carolina horsenettle, Italian thistle, leafy spurge, purple loosestrife, Russian knapweed Graminoids: Quackgrass, sorghum, Sudangrass Shrubs: Multiflora rose Vines: Field bindweed Kansas Forbs: Canada thistle, Chinese lespedeza, leafy spurge, musk thistle, Russian knapweed Graminoids: Quackgrass Vines: Field bindweed, kudzu Kentucky Forbs: Canada thistle, musk thistle Shrubs: Multiflora rose Vines: Kudzu Maine Aquatics: Eurasian watermilfoil, hydrilla, parrot feather, variable watermilfoil, water chestnut (Continued )

668 n STATE-BY-STATE DESIGNATIONS OF INVASIVE OR NOXIOUS WEEDS Maryland Forbs: Bull thistle, Canada thistle, musk thistle, plumeless thistle Graminoids: Sorghum, Sudangrass Massachusetts Aquatic: Anchored waterhyacinth, Eurasian watermilfoil, giant salvinia, hydrilla, parrotfeather, variable watermilfoil, water chestnut Forbs: garlic mustard, giant hogweed, goutweed, Japanese knotweed, leafy spurge, perennial pepperweed, purple loosestrife, spotted knapweed Graminoids: African feathergrass, Asiatic sand sedge, Brazilian satintail, common reed, Japanese stilt grass, kikuyugrass, kyasuma grass, mission grass Shrubs: Amur honeysuckle, Bell’s honeysuckle, common barberry, Japanese barberry, Morrow’s honeysuckle, multiflora rose, shrubby Russian thistle, Tatarian honeysuckle, tropical soda apple, turkey berry Trees: Autumn olive, melaleuca, tree of heaven Vines: Black swallow-wort, dodders, Japanese honeysuckle, Japanese hops, kudzu, mile-aminute, Oriental bittersweet, pale swallow-wort, porcelainberry, wetlands nightshade Michigan Forbs: Canada thistle, purple loosestrife Vines: Dodders, field bindweed Minnesota Forbs: Bull thistle, Canada thistle, garlic mustard, giant hogweed, leafy spurge, musk thistle, plumeless thistle, purple loosestrife Graminoids: African feathergrass, Brazilian satintail, cogongrass, kikuyugrass, kyasuma grass, mission grass Shrubs: Shrubby Russian thistle, tropical soda apple, turkey berry Vines: Dodders, field bindweed Mississippi Aquatic: Giant salvinia, hydrilla Forbs: Fig buttercup Graminoids: Brazilian satintail, cogongrass Shrubs: Tropical soda apple Vines: Kudzu Missouri Forbs: Canada thistle, musk thistle, purple loosestrife, Scotch thistle Shrubs: Multiflora rose Vines: Field bindweed, kudzu Montana Aquatic: Eurasian watermilfoil Forbs: Canada thistle, common St. Johnswort, Dalmatian toadflax, diffuse knapweed, dyer’s woad, leafy spurge, perennial pepperweed, purple loosestrife, Russian knapweed, spotted knapweed, yellow starthistle, yellow toadflax Trees: Tamarisk Vines: Field bindweed

STATE-BY-STATE DESIGNATIONS OF INVASIVE OR NOXIOUS WEEDS n 669 Nebraska Forbs: Canada thistle, diffuse knapweed, leafy spurge, musk thistle, plumeless thistle, purple loosestrife, spotted knapweed Trees: Tamarisk Nevada Aquatic: Eurasian watermilfoil, giant salvinia, hydrilla Forbs: Canada thistle, Carolina horsenettle, common St. Johnswort, Dalmatian toadflax, diffuse knapweed, dyer’s woad, Iberian knapweed, leafy spurge, Malta starthistle, musk thistle, perennial pepperweed, purple loosestrife, purple starthistle, Russian knapweed, Scotch thistle, spotted knapweed, Sudangrass Shrubs: Silverleaf nightshade Trees: Tamarisk Vines: Black swallow-wort, field bindweed, pale swallow-wort New Hampshire Forbs: Garlic mustard, giant hogweed, Japanese knotweed spotted knapweed Shrubs: Bell’s honeysuckle, common barberry, Morrow’s honeysuckle, multiflora rose, Tatarian honeysuckle Trees: Autumn olive, tree of heaven Vines: Black swallow-wort, Japanese honeysuckle, Oriental bittersweet, pale swallow-wort New Mexico Aquatic: Eurasian watermilfoil, hydrilla Forbs: Bull thistle, Canada thistle, Dalmatian toadflax, diffuse knapweed, dyer’s woad, halogeton, leafy spurge, Malta starthistle, musk thistle, perennial pepperweed, purple loosestrife, purple starthistle, Russian knapweed, Scotch thistle, spotted knapweed, yellow starthistle, yellow toadflax Trees: Russian olive, tamarisk Vines: Field bindweed North Carolina Aquatic: Anchored waterhyacinth, common salvinia, Eurasian watermilfoil, hydrilla, water chestnut Forbs: Canada thistle, giant hogweed, musk thistle, plumeless thistle, purple loosestrife Graminoids: African feathergrass, Brazilian satintail, cogongrass, kikuyugrass, kyasuma grass, mission grass Shrubs: Shrubby Russian thistle, tropical soda apple, turkey berry Trees: Melaleuca Vines: Dodders, mile-a-minute, Oriental bittersweet, wetlands nightshade North Dakota Forbs: Canada thistle, Dalmatian toadflax, diffuse knapweed, leafy spurge, musk thistle, purple loosestrife, Russian knapweed, spotted knapweed, yellow starthistle Trees: Tamarisk Vines: Field bindweed Ohio Forbs: Canada thistle, giant hogweed, musk thistle, prickly Russian thistle, purple loosestrife (Continued )

670 n STATE-BY-STATE DESIGNATIONS OF INVASIVE OR NOXIOUS WEEDS Graminoids: Sorghum, Sudangrass Vines: Mile-a-minute Oklahoma Forbs: Canada thistle, musk thistle, Scotch thistle Oregon Aquatic: Anchored waterhyacinth, Eurasian watermilfoil, giant salvinia, hydrilla, water chestnut Forbs: Buffalobur nightshade, bull thistle, burning bush, Canada thistle, common St. Johnswort, Dalmatian toadflax, diffuse knapweed, dyer’s woad, garlic mustard, giant hogweed, giant knotweed, hairy whitetop, halogeton, Iberian knapweed, Italian thistle, Japanese knotweed, leafy spurge, lens-pod cress, musk thistle, perennial pepperweed, plumeless thistle, purple loosestrife, purple starthistle, Russian knapweed, Scotch thistle, spotted knapweed, squarrose knapweed, yellow starthistle, yellow toadflax Graminoids: African feathergrass, Brazilian satintail, cogongrass, common cordgrass, denseflowered cordgrass, kikuyugrass, kyasuma grass, medusahead, mission grass, quackgrass, salt meadow cordgrass, smooth cordgrass Shrubs: French broom, Gorse, Himalayan blackberry, Portuguese broom, Scotch broom, shrubby Russian thistle, silverleaf nightshade, Spanish broom, tropical soda apple, turkey berry Trees: Melaleuca, tamarisk Vines: Dodders, English ivy, field bindweed, kudzu, wetlands nightshade Pennsylvania Forbs: Bull thistle, Canada thistle, giant hogweed, musk thistle, purple loosestrife Graminoids: Sorghum, Sudangrass Shrubs: Multiflora rose Vines: Kudzu, mile-a-minute South Carolina Aquatic: Anchored waterhyacinth, Eurasian watermilfoil, giant salvinia, hydrilla, water chestnut, waterhyacinth Forbs: Giant hogweed, purple loosestrife, Russian knapweed Graminoids: African feathergrass, Brazilian satintail, cogongrass, common reed, kikuyugrass, kyasuma grass, mission grass Shrubs: Shrubby Russian thistle, tropical soda apple, turkey berry Trees: Melaleuca Vines: Dodders, mile-a-minute, wetlands nightshade South Dakota Aquatic: Eurasian watermilfoil Forbs: Canada thistle, common St. Johnswort, Dalmatian toadflax, diffuse knapweed, leafy spurge, musk thistle, perennial pepperweed, plumeless thistle, purple loosestrife, Russian knapweed, spotted knapweed, yellow starthistle, yellow toadflax Shrubs: Multiflora rose Trees: Tamarisk Vines: Dodders, field bindweed Tennessee Forbs: Purple loosestrife Shrubs: Tropical soda apple

STATE-BY-STATE DESIGNATIONS OF INVASIVE OR NOXIOUS WEEDS n 671 Texas Aquatic: Anchored waterhyacinth, common salvinia, Eurasian watermilfoil, giant salvinia, hydrilla, waterhyacinth Forbs: Purple loosestrife Graminoids: Giant reed Shrubs: Tropical soda apple Trees: Brazilian peppertree, melaleuca, tamarisk Vines: Dodders, field bindweed, kudzu Utah Forbs: Canada thistle, diffuse knapweed, dyer’s woad, leafy spurge, musk thistle, perennial pepperweed, purple loosestrife, Russian knapweed, Scotch thistle, spotted knapweed, squarrose knapweed, yellow starthistle Graminoids: Medusahead, quackgrass Vines: Field bindweed Vermont Aquatic: Anchored waterhyacinth, Eurasian watermilfoil, giant salvinia, hydrilla, parrotfeather, variable watermilfoil, water chestnut, waterhyacinth Forbs: Garlic mustard, giant hogweed, goutweed, Japanese knotweed, purple loosestrife, spotted knapweed Graminoids: African feathergrass, Brazilian satintail, cogongrass, common reed, kikuyugrass, kyasuma grass, mission grass Shrubs: Amur honeysuckle, Bell’s honeysuckle, Morrow’s honeysuckle, shrubby Russian thistle, Tatarian honeysuckle, tropical soda apple, turkey berry Trees: Melaleuca, tree of heaven Vines: Black swallow-wort, dodders, Japanese honeysuckle, Oriental bittersweet, pale swallowwort, wetlands nightshade, white swallow-wort Virginia Forbs: Purple loosestrife Washington Aquatic: Eurasian watermilfoil, hydrilla, parrotfeather, water chestnut Forbs: Buffalobur nightshade, bull thistle, burning bush, Canada thistle, common St. Johnswort, Dalmatian toadflax, diffuse knapweed, dyer’s woad, garlic mustard, giant hogweed, giant knotweed, hairy whitetop, Italian thistle, Japanese knotweed, leafy spurge, musk thistle, perennial pepperweed, plumeless thistle, purple loosestrife, purple starthistle, Russian knapweed, Scotch thistle, spotted knapweed, yellow starthistle, yellow toadflax Graminoids: Common cordgrass, common reed, dense-flowered cordgrass, salt meadow cordgrass, smooth cordgrass Shrubs: Gorse, Scotch broom, silverleaf nightshade, Spanish broom Trees: Tamarisk Vines: Alfalfa dodder, English ivy, field bindweed, kudzu West Virginia Forbs: Musk thistle, plumeless thistle Shrubs: Multiflora rose Vines: Kudzu (Continued )

672 n STATE-BY-STATE DESIGNATIONS OF INVASIVE OR NOXIOUS WEEDS Trees: Autumn olive Wisconsin Forbs: Canada thistle, leafy spurge, purple loosestrife Shrubs: Multiflora rose Vines: Field bindweed Wyoming Forbs: Canada thistle, common St. Johnswort, Dalmatian toadflax, diffuse knapweed, dyer’s woad, hairy whitetop, leafy spurge, musk thistle, perennial pepperweed, plumeless thistle, purple loosestrife, Russian knapweed, Scotch thistle, spotted knapweed, yellow toadflax Graminoids: Quackgrass Trees: Tamarisk Vines: Field bindweed

n Pathways of Introduction for Plants Intentional Aesthetics, Ornamentals, and Garden Escapees

Brazilian peppertree (Schinus terebinthifolius)

Brooms (Cytisus spp., Genista spp.) Burning bush (Bassia scoparia, Euonymus atropurpurea) Carrotwood (Cupaniopsis anacardioides) Cherokee rose (Rosa laevigata) Chinaberry (Melia azedarach) Chocolate vine (Akebia quinata) Crimson fountain grass (Pennisetum setaceum) English ivy (Hedera helix) Exotic bush honeysuckles (Lonicera spp.) Field bindweed (Convolvulus arvensis) Fig buttercup (Ficaria verna) Fire tree (Morella faya) Giant hogweed (Heracleum mantegazzianum) Giant reed (Arundo donax) Gorse (Ulex europaeus) Goutweed (Aegopodium podagraria) Japanese barberry (Berberis thunbergii) Japanese climbing fern (Lygodium japonicum) Japanese honeysuckle (Lonicera japonica) Japanese hops (Humulus japonicus) Japanese knotweed (Fallopia japonica) Jubata grass (Cortaderia jubata) Kahili ginger (Hedychium gardnerianum) Koster’s curse (Clidemia hirta) (Continued )

674 n PATHWAYS OF INTRODUCTION FOR PLANTS Kudzu (Pueraria montana) Lantana (Lantana camara) Mccartney rose (Rosa bracteata) Melaleuca (Melaleuca quinquenervia) Multiflora rose (Rosa multiflora) Old World climbing fern (Lygodium microphyllum) Oriental bittersweet (Celastrus orbiculatus) Pampas grass (Cortaderia selloana) Paper mulberry (Broussonetia papyrifera) Porcelainberry (Ampelopsis glandulosa, var. brevipedunculata Princess tree (Paulownia tomentosa) Purple loosestrife (Lythrum salicaria) Russian olive (Elaeagnus angustifolia) Silk tree (Albizia julibrissin) Strawberry guava (Psidium cattleianum) Swallow-worts (Cynanchum spp.) Tamarisk (Tamarix chinensis, T. ramosissima) Toadflax (Linaria dalmatica ssp. dalmatica, L. vulgaris) Tree of heaven (Ailanthus altissima) Velvet tree (Miconia calvescens) Waterhyacinth (Eichhornia crassipes) Winter creeper (Euonymus fortunei) Wisteria (Wisteria sinensis, W. floribunda) Aquarium Trade

Common salvinia (Salvinia minima) Giant salvinia (Salvinia molesta) Hydrilla (Hydrilla verticillata) Waterhyacinth (Eichhornia crassipes)

Botanical Gardens

Exotic bush honeysuckles (Lonicera spp.) Japanese barberry (Berberis thunbergii) Koster’s curse (Clidemia hirta) Velvet tree (Miconia calvescens) Water chestnut (Trapa natans)

Domestic Use (Dye, Fish Poison)

Common mullein (Verbascum thapsus)

PATHWAYS OF INTRODUCTION FOR PLANTS n 675 Dyer’s woad (Isatis tinctoria) Gorse (Ulex europaeus) Yellow toadflax (Linaria vulgaris) Erosion Control/Bank Stabilization

Asiatic sand sedge (Carex kobomugi) Australian pine (Casuarina equisetifolia) Brooms (Cytisus spp., Genista spp., Sarothamnus spp.) Buffelgrass (Pennisetum ciliare) Cogongrass (Imperata cylindrica) Exotic bush honeysuckles (Lonicera spp.) Giant reed (Arundo donax) Ice plant (Carpobrotus edulis) Japanese knotweed (Fallopia japonica) Kikuyugrass (Pennisetum clandestinum) Kudzu (Pueraria montana) Melaleuca (Melaleuca quinquenervia) Multiflora rose (Rosa multiflora) Russian olive (Elaeagnus angustifolia) Smooth cordgrass (Spartina alterniflora)

Livestock Forage or Fodder

Buffelgrass (Pennisetum ciliare) Cogon grass (Imperata cylindrica) Common cordgrass (Spartina anglica) Gorse (Ulex europaeus) Johnsongrass (Sorghum halepense) Kikuyugrass (Pennisetum clandestinum) West Indian marsh grass (Hymenachne amplexicaulis)

Medicinal

Asiatic colubrina (Colubrina asiatica) Common mullein (Verbascum thapsus) Common St. Johnswort (Hypericum perforatum) Field bindweed (Convolvulus arvensis) Garlic mustard (Alliaria petiolata) Japanese hops (Humulus japonicus) Purple loosestrife (Lythrum salicaria) (Continued )

676 n PATHWAYS OF INTRODUCTION FOR PLANTS Food and Drink

Fire tree (Morella faya) Garlic mustard (Alliaria petiolata) Giant hogweed (Heracleum mantegazzianum) Himalayan blackberry (Rubus armeniacus) Strawberry guava (Psidium cattleianum) Yellow Himalayan raspberry (Rubus ellipticus)

Packing Material

Cogon grass (Imperata cylindrica) Japanese stilt grass (Microstegium vimineum) Princess tree (Paulownia tomentosa) Smooth cordgrass (Spartina alterniflora)

Reclamation

Brooms (Cytisus spp., Genista spp., Sarothamnus spp.) Dense-flowered cordgrass (Spartina densiflora) Exotic bush honeysuckles (Lonicera spp.) Silk tree (Albizia julibrissin) Melaleuca (Melaleuca quinquenervia)

Timber/Reforestation/ Firewood

Carrotwood (Cupaniopsis anacardioides) Fire tree (Morella faya) Melaleuca (Melaleuca quinquenervia)

Wildlife Habitat or Food

Chinese lespedeza (Lespedeza cuneata) Exotic bush honeysuckles (Lonicera spp.) Multiflora rose (Rosa multiflora) Russian olive (Elaeagnus angustifolia)

Windbreaks/ Fencerows

Melaleuca (Melaleuca quinquenervia) Russian olive (Elaeagnus angustifolia) Tamarisk (Tamarisk chinensis, T. ramosissima)

Unintentional Ballast Water Discharge

Asiatic sand sedge (Carex kobomugi)a Cheatgrass (Bromus tectorum)

PATHWAYS OF INTRODUCTION FOR PLANTS n 677 Common reed (Phragmites australis) Crystalline ice plant (Mesembryanthemum crystallinum) Dense-flowered cordgrass (Spartina densiflora) Eurasian watermilfoil (Myriophyllum spicatum) Hoary cress (Cardaria draba) Leafy spurge (Euphorbia esula) Musk thistle (Carduus nutans) Purple loosestrife (Lythrum salicaria) Smooth cordgrass (Spartina alterniflora) Spotted knapweed (Centaurea stoebe) Contaminant in Seeds Canadian thistle (Cirsium arvense)a or Plants Cheatgrass (Bromus tectorum) Dyer’s woad (Isatis tinctoria) Halogeton (Halogeton glomeratus) Koster’s curse (Clidemia hirta) Leafy spurge (Euphorbia esula) Medusahead (Taeniatherum caput-medusae)a Perennial pepperweed (Lepidium latifolium) Prickly Russian thistle (Salsola tragus) Quackgrass (Elymus repens) Spotted knapweed (Centaurea stoebe) Tropical soda apple (Solanum viarum) Yellow starthistle (Centaurea solstitialis)a Escapes from Aquaculture

Common salvinia (Salvinia minima) Giant salvinia (Salvinia molesta) Hydrilla (Hydrilla verticillata) Water chestnut (Trapa natans) Waterhyacinth (Eichhornia crassipes)

Ocean Currents

Asiatic colubrina (Colubrina asiatica) West Indian marsh grass (Hymenachne amplexicaulis)

a

Probable means of introduction

n Impacts of Invasive Plants Agriculture: Crops and Orchards

Forbs Canada thistle Dyer’s woad Leafy spurge Prickly Russian thistle Toadflax Graminoids Cheatgrass Johnsongrass Kikuyugrass Quackgrass Shrubs Lantana Multiflora rose Tropical soda apple Trees Strawberry guava Vines Field bindweed Japanese dodder Mile-a-minute Swallow-worts

Animal Health

Forbs Canada thistle Common St. Johnswort Giant hogweed Halogeton Leafy spurge

IMPACTS OF INVASIVE PLANTS n 679 Toadflax Yellow starthistle Graminoids Buffelgrass Cheatgrass Johnsongrass Kikuyugrass Medusahead Shrubs Brooms Lantana Rattlebox Vines Field bindweed Fire Hazard

Forbs Canada thistle Common St. Johnswort Prickly Russian thistle Spotted knapweed Graminoids Buffelgrass Cheatgrass Cogongrass Fountain grass Giant reed Johnsongrass Jubata grass Kikuyugrass Medusahead Pampas grass Shrubs Brooms Gorse (Continued )

680 n IMPACTS OF INVASIVE PLANTS Lantana Trees Melaleuca Russian olive Vines Climbing ferns Forage: Rangeland, Pasture, Hay

Forbs Chinese lespedeza Common St. Johnswort Dyer’s woad Halogeton Leafy spurge Musk thistle Perennial pepperweed Spotted knapweed Toadflax Yellow starthistle Graminoids Cheatgrass Johnsongrass Kikuyugrass Medusahead Quackgrass Shrubs Gorse Lantana Multiflora rose Tropical soda apple Vines Swallow-worts

Human Health: Disease, Illness, Allergies, Poisonous

Aquatic Eurasian watermilfoil Waterhyacinth

IMPACTS OF INVASIVE PLANTS n 681 Forbs Giant hogweed Leafy spurge Graminoids Johnsongrass Shrubs Brooms Exotic bush honeysuckles Lantana Rattlebox Tropical soda apple Trees Australian pine Chinaberry Melaleuca Paper mulberry Vines English ivy Japanese hops Oriental bittersweet Wisteria Hydrology: Drainage, Water Transportation, Water Quality

Aquatic Eurasian watermilfoil Common salvinia Giant salvinia Hydrilla Waterhyacinth Forbs Japanese knotweed Kahili ginger Purple loosestrife Graminoids Giant reed (Continued )

682 n IMPACTS OF INVASIVE PLANTS Cordgrasses West Indian marsh grass Shrubs Rattlebox Trees Australian pine Brazilian peppertree Russian olive Strawberry guava Tamarisk Velvet tree Native Ecosystems: Displacing Plants and Reducing Biodiversity

Aquatic Eurasian watermilfoil Common salvinia Giant salvinia Hydrilla Water chestnut Waterhyacinth Forbs Canada thistle Chinese lespedeza Common mullein Common St. Johnswort Dyer’s woad Fig buttercup Garlic mustard Giant hogweed Goutweed Halogeton Ice plant Japanese knotweed Kahili ginger Leafy spurge

IMPACTS OF INVASIVE PLANTS n 683 Musk thistle Perennial pepperweed Prickly Russian thistle Purple loosestrife Spotted knapweed Toadflax Yellow starthistle Graminoids Asiatic sand sedge Buffelgrass Cheatgrass Cogongrass Common reed Cordgrasses Fountain grass Giant reed Japanese stiltgrass Johnsongrass Jubata grass Pampas grass Medusahead Quackgrass West Indian marsh grass Shrubs Asiatic colubrina Brooms Exotic bush honeysuckles Gorse Japanese barberry Koster’s curse Lantana Multiflora rose Rattlebox (Continued )

684 n IMPACTS OF INVASIVE PLANTS Tropical soda apple Yellow Himalayan raspberry Trees Australian pine Brazilian peppertree Carrotwood Chinaberry Firetree Melaleuca Paper mulberry Princess tree Russian olive Silk tree Strawberry guava Tamarisk Tree of heaven Velvet tree Vines Chocolate vine Climbing ferns English ivy Field bindweed Japanese dodder Japanese honeysuckle Japanese hops Kudzu Mile-a-minute Oriental bittersweet Porcelainberry Swallow-worts Winter creeper Wisteria Plant Health: Hosts for Pests or Parasitic

Forbs

IMPACTS OF INVASIVE PLANTS n 685 Canada thistle Common mullein Prickly Russian thistle Graminoids Johnsongrass Shrubs Tropical soda apple Vines English ivy Field bindweed Japanese dodder Japanese honeysuckle Recreational Activities

Aquatic Eurasian watermilfoil Common salvinia Giant salvinia Hydrilla Water chestnut Waterhyacinth Forbs Japanese knotweed Yellow starthistle Graminoids Jubata grass Pampas grass Shrubs Lantana Multiflora rose Rattlebox Trees Brazilian peppertree Vines Mile-a-minute (Continued )

686 n IMPACTS OF INVASIVE PLANTS Water Use (Excess)

Forbs Toadflax Yellow starthistle Graminoids Giant reed Shrubs Strawberry guava Trees Russian olive Tamarisk

n Major Organizations and Publications Concerned about Invasive Plants

From USDA Invasive Plants website (http://plants.usda.gov/java/noxious), with the exception of World’s Worst 100. Abbreviations at front of listings are used in the table following this one, “Plant Species Listed as Invasive or Noxious by Organizations and State and Federal Governments.”

Global Scope World’s Worst 100: Lowe, S., M. Browne, S. Boudjelas, and M. De Poorter. 100 of the World’s Worst Invasive Alien Species. A selection from the Global Invasive Species Database. Invasive Species Specialist Group (ISSG), Species Survival Commission (SSC) of the World Conservation Union (IUCN), 2000. http://www.issg.org/database/species/search.asp?st=100ss.

National Scope Federal: U.S. Department of Agriculture. Animal and Plant Health Inspection Service. Plant Protection and Quarantine. Federal Noxious Weed List (24 May 2006). USDA Animal and Plant Health Inspection Service, Washington, DC, May 24, 2006. http://plants.usda.gov/java/noxious ?rptType=Federal. Also, USDA APHIS Plant Protection and Quarantine. Federal Domestic Quarantines. USDA APHIS Plant Protection and Quarantine, Washington, DC, May 24, 2006. http://www.aphis.usda.gov/plant_health/plant_pest_info.

State and Regional Scope Cal-IPC: California Invasive Plant Council. California Invasive Plant Inventory. Cal-IPC Publication 2006-02. California Invasive Plant Council, Berkeley, February 1, 2007. http://www.cal-ipc.org/ ip/inventory/index.php. FLEPPC: Florida Exotic Pest Plant Council. Invasive Plant List. Florida Exotic Pest Plant Council, Florida, October 19, 1999. http://www.fleppc.org. HEAR: Hawaiian Ecosystems at Risk Project. Information Index for Selected Alien Plants in Hawaii. USDI, Geological Survey. Biological Resources Division, Haleakala Field Station, Makawao, HI, October 20, 2003. http://www.hear.org/plants/. KY: Haragan, P. D. Weeds of Kentucky and Adjacent States: A Field Guide. Lexington: University Press of Kentucky, 1991. N’EAST: Uva, R. H., J. C. Neal, and J. M. DiTomaso. Weeds of the Northeast. Ithaca, NY: Cornell University Press, 1997. NE&GP: Nebraska Department of Agriculture, Bureau of Plant Industry, Lincoln, NE. Publications: Stubbendieck, James, Mitchell L. Coffin, and L. M. Landholt, Weeds of the Great Plains, 2005. (Previous edition: Stubbendieck, J., G. Y. Friisoe, and M. R. Bolick. Weeds of Nebraska and the Great Plains. 1994.) http://www.agr.state.ne.us/division/bpi/nwp/nwp1.htm.

688 n MAJOR ORGANIZATIONS AND PUBLICATIONS CONCERNED ABOUT INVASIVE PLANTS SEEPPC: Southeast Exotic Pest Plant Council. Invasive Exotic Pest Plants in Tennessee. Research Committee of the Tennessee Exotic Pest Plant Council, Tennessee, October 19, 1999. http:// www.se-eppc.org/weeds.cfm. SWSS: Southern Weed Science Society. Weeds of the United States and Canada. CD-ROM. Southern Weed Science Society, Champaign, IL. http://www.swss.ws. WI: Wisconsin Department of Natural Resources. Hoffmann, R., and K. Kearns, eds. Wisconsin Manual of Control Recommendations for Ecologically Invasive Plants. Madison: Wisconsin Department of Natural Resources, 1997. http://dnr.wi.gov/invasives/publications/manual/manual_toc.htm. WSWS: Western Society of Weed Science. Whitson, T. D. (ed.) et al. Weeds of the West. Western Society of Weed Science in cooperation with Cooperative Extension Services, University of Wyoming, Laramie, WY, 2006. http://www.wsweedscience.org/.

n Plant Species Listed as Invasive

or Noxious by Organizations and State and Federal Governments

Following are species discussed in the text that have been declared invasive by organizations or by federal or state governments.

Key to Organization Abbreviations Cal-IPC Federal FLEPPC HEAR KY N’EAST NE&GP SEEPPC SWSS WI World’s Worst 100 WSWS

California Invasive Plant Council. Federal Noxious Weed List. Florida Exotic Pest Plant Council. USDI, Geological Survey. Hawaiian Ecosystems at Risk Project. Weeds of Kentucky and Adjacent States: A Field Guide. Weeds of the Northeast. Weeds of Nebraska and the Great Plains. Southeast Exotic Pest Plant Council. Southern Weed Science Society. Wisconsin Manual of Control Recommendations for Ecologically Invasive Plants. 100 of the World’s Worst Invasive Alien Species. Western Society of Weed Science.

More information about these organizations is found in the previous list: “Major Organizations and Publications Concerned about Invasive Plants.” Aquatics

Organizations and Federal or State Governments

Anchored waterhyacinth Common salvinia Eurasian watermilfoil

Federal, AL, AZ, CA, FL, MA, NC, OR, SC, TX, VT TX, FL, NC Cal-IPC, FLEPPC, SEEPPC, WI, AL, CO, CT, FL, ID, MA, MT, NV, NM, NC, OR, SC, SD, TX, VT, WA Cal-IPC, Federal, AL, AZ, CA, CO, CT, FL, MA, MS, NV, OR, SC, TX, VT Cal-IPC, FLEPPC, SEEPPC, Federal, AL, AZ, CA, CO, CT, FL, ME, MA, MS, NV, NM, NC, OR, SC, TX, VT, WA Cal-IPC, SEEPPC, AL, CT, ME, MA, VT, WA CT, ME, MA, VT AL, AZ, CT, FL, ME, MA, NC, OR, SC, VT, WA World’s Worst 100, Cal-IPC, FLEPPC, SWSS, AL, AZ, CA, CT, FL, SC, TX, VT

Giant salvinia Hydrilla Parrotfeather Variable watermilfoil Water chestnut Waterhyacinth

690 n PLANT SPECIES LISTED AS INVASIVE

Forbs Barbwire Russian thistle Buffalobur nightshade Bull thistle

Organizations and Federal or State Governments

AR, CA NE&GP, SWSS, WSWS, ID, OR, WA Cal-IPC, N’EAST, NE&GP, SEEPPC, SWSS, WSWS, AR, CO, IA, MD, MN, NM, OR, PA, WA Burning bush N’EAST, NE&GP, SWSS, WSWS, Federal, CT, OR, WA Canada thistle Cal-IPC, N’EAST, NE&GP, SEEPPC, SWSS, WI, WSWS, Federal, AK, AR, AZ, CA, CO, CT, DE, HI, ID, IL, IN, IA, KS, KY, MD, MI, MN, MO, MT, NB, NV, NM, NC, ND, OH, OK, OR, PA, SD, UT, WA, WI, WY Canary Island St. Johnswort Cal-IPC, HEAR Carolina horsenettle KY, N’EAST, NE&GP, SWSS, AK, AZ, AR, CA, HI, IA, NV Chinese lespedeza SEEPPC, Federal, CO, KS Common mullein Cal-IPC, HEAR, KY, N’EAST, NE&GP, SEEPPC, SWSS, WI, WSWS, Federal, CO, HI Common St. Johnswort Cal-IPC, NE&GP, SEEPPC, SWSS, WI, WSWS, Federal, CA, CO, MT, NV, OR, SD, WA, WY Crystalline ice plant Cal-IPC Dalmatian toadflax WSWS, Federal, AZ, CA, CO, ID, MT, NV, NM, ND, OR, SD, WA, WY Diffuse knapweed WSWS, Federal, AZ, CA, CO, ID, MT, NB, NV, NM, ND, OR, SD, UT, WA, WY Dyer’s woad WSWS, Federal, AZ, CA, CO, ID, MT, NV, NM, OR, UT, WA, WY Fig buttercup CT, MS Garlic mustard SEEPPC, WI, Federal, AL, CT, MA, MN, NH, OR, VT, WA Giant hogweed Federal, AL, CA, CT, FL, MA, MN, NH, NC, OH, OR, PA, SC, VT, WA Giant knotweed SEEPC, Federal, CA, CT, OR, WA Goutweed Federal, CT, MA, VT Hairy whitetop Federal, AK, AZ, CA, HI, OR, WA, WY Halogeton Cal-IPC, WSWS, Federal, AZ, CA, CO, HI, NM, OR Hemp sesbania KY, SWSS, AR Iberian knapweed WSWS, AZ, CA, NV, OR Ice plant Cal-IPC Italian thistle Cal-IPC, WSWS, AR, CA, IA, OR, WA Japanese knotweed World’s Worst 100, KY, N’EAST, SEEPPC, WSWS, Federal, AL, CA, CT, MA, NH, OR, VT, WA Kahili ginger World’s Worst 100, HEAR Leafy spurge World’s Worst 100, Cal-IPC, N’EAST, NE&GP, SWSS, WI, WSWS, Federal, AK, AZ, CA, CO, CT, HI, ID, IA, KS, MA, MN, MT, NB, NV, NM, ND, OR, SD, UT, WA, WI, WY Lens-pod hoary cress Cal-IPC, Federal, AZ, CA, OR Malta starthistle Cal-IPC, NV, NM Moth mullein SWSS, WSWS, CO Musk thistle KY, N’EAST, NE&GP, SEEPPC, SWSS, WI, WSWS, Federal, CA, CO, ID, IL, IA, KS, KY, MD, MN, MO, NB, NV, NM, NC, ND, OH, OK, OR, PA, SD, UT, WA, WV, WY Oppositeleaf Russian thistle AR Perennial Pepperweed Cal-IPC, WSWS, Federal, AK, CA, CO, CT, HI, ID, MA, MT, NV, NM, OR, SD, UT, WA, WY

PLANT SPECIES LISTED AS INVASIVE n 691 Forbs

Organizations and Federal or State Governments

Plumeless thistle

Yellow toadflax

NE&GP, WI, WSWS, AZ, AR, CA, CO, ID, MD, MN, NB, NC, OR, SD, WA, WV, WY NE&GP, SWSS, WSWS, AR, CA, HI, OH World’s Worst 100, Cal-IPC, N’EAST, NE&GP, SEEPPC, SWSS, WI, WSWS, Federal, AL, AZ, AR, CA, CO, CT, FL, ID, IN, IA, MA, MI, MN, MO, MT, NB, NV, NM, NC, ND, OH, OR, PA, SC, SD, TN, TX, UT, VT, VA, WA, WI, WY AZ, CA, NV, NM, OR, WA NE&GP, SWSS, WSWS, Federal, AK, AZ, CA, CO, HI, ID, IA, KS, MT, NV, NM, ND, OR, SC, SD, UT, WA, WY NE&GP, SWSS, WSWS, AZ, AR, CA, CO, CT, ID, MO, NV, NM, OK, OR, UT, WA, WY AZ, CA AR, CA Cal-IPC, KY, N’EAST, NE&GP, SEEPPC, SWSS, WI, WSWS, Federal, AZ, CA, CO, CT, ID, MA, MT, NB, NV, NM, ND, OR, SD, UT, WA, WY WSWS, AZ, CA, CO, NV, OR, UT CA Cal-IPC, SWSS, WSWS, Federal, AZ, CA, CO, ID, MT, NV, NM, ND, OR, SD, UT, WA N’EAST, NE&GP, WSWS, Federal, ID, MT, NV, NM, OR, SD, WA, WY

Graminoids

Organizations and Federal or State Governments

African feathergrass Asiatic sand sedge Bald brome Brazilian satintail Buffelgrass California satintail Cheatgrass

Federal, AL, CA, FL, MA, MN, NC, OR, SC, VT CT, MA SEEPPC, SWSS, AR Federal, AL, CA, FL, MA, MN, MS, NC, OR, SC, VT HEAR, Federal, AZ CA Cal-IPC, FLEPPC, HEAR, N’EAST, NE&GP, SEEPPC, SWSS, WSWS, Federal, CO, CT World’s Worst 100, FLEPPC, SWSS, Federal, AL, CA, FL, HI, MN, MS, NC, OR, SC, VT Cal-IPC, CA, WA N’EAST, SEEPPC, Federal, AL, CT, MA, SC, VT, WA Cal-IPC, HEAR, HI Cal-IPC, OR, WA FLEPPC Cal-IPC, HEAR, SEEPPC, Federal, TX KY, NE&GP, SEEPPC, SWSS, WSWS, Federal SEEPPC, Federal, AL, CT, MA Cal-IPC, HEAR, HI HEAR, WSWS, Federal, AL, CA, FL, MA, MN, NC, OR, SC, VT Federal, AL, CA, FL, MA, MN, NC, OR, SC, VT Cal-IPC, SWSS, WSWS, Federal, CA, CO, NV, OR, UT Federal, AL, CA, FL, MA, MN, NC, OR, SC, VT Cal-IPC, HEAR KY, N’EST, NE&GP, SWSS, WI, WSWS, Federal, AK, AZ, CA, CO, HI, IA, KS, OR, UT, WY

Prickly Russian thistle Purple loosestrife

Purple starthistle Russian knapweed Scotch thistle Sicilian starthistle Slender Russian thistle Spotted knapweed

Squarrose knapweed Western horsenettle Yellow starthistle

Cogongrass Common cordgrass Common reed Crimson fountain grass Dense-flowered cordgrass Elephant grass Giant reed Japanese brome Japanese stilt grass Jubata grass Kikuyugrass Kyasuma grass Medusahead Mission grass Pampas grass Quackgrass

(Continued )

692 n PLANT SPECIES LISTED AS INVASIVE Graminoids

Organizations and Federal or State Governments

Ryebrome Salt meadow cordgrass Smooth brome Smooth cordgrass Soft brome Sorghum Sudangrass West Indian marsh grass

SEEPPC, SWSS, WSWS, AR Cal-IPC, OR, WA NE&GP, SEEPPC, WI, Federal Cal-IPC, OR, WA SEEPPC, SWSS, WSWS, Federal N’EAST, NE&GP, SWSS, IN, IA, MD, NV, OH, PA N’EAST, NE&GP, SWSS, IN, IA, MD, NV, OH, PA FLEPPC

Shrubs

Organizations and Federal or State Governments

Amur honeysuckle Asiatic colubrina Bell’s honeysuckle Canary Island St. Johnswort Common barberry French broom Gorse Himalayan blackberry Japanese barberry Koster’s curse Lantana Morrow’s honeysuckle Multiflora rose

SEEPPC, WI, Federal, CT, MA, VT FLEPPC CT, MA, NH, VT HEAR WI, Federal, CT, MA, NH Cal-IPC, Federal, CA, HI, OR Cal-IPC, HEAR, WSWS, Federal, CA, HI, OR, WA Cal-IPC, HEAR, N’EAST, Federal, OR SEEPPC, WI, Federal, CT, MA World’s Worst 100, HEAR, HI World’s Worst 100, FLEPPC, HEAR SEEPPC, WI, Federal, CT, MA, NH, VT N’EAST, SEEPPC, SWSS, WI, Federal, AL, CT, IN, IA, KY, MA, MO, NH, PA, SD, WV, WI Portuguese broom Cal-IPC, Federal, OR Rattlebox Cal-IPC, FLEPPC Sawtooth blackberry HEAR, N’EAST, HI Scotch broom Cal-IPC, WSWS, Federal, CA, HI, ID, OR, WA Shrubby Russian thistle Federal, AL, AR, CA, FL, MA, MN, NC, OR, SC, VT Silverleaf nightshade SWSS, WSWS, AR, CA, HI, ID, NV, OR, WA Snowpeaks raspberry HEAR, N’EAST, HI Spanish broom Cal-IPC, Federal, HI, OR, WA Tatarian honeysuckle N’EAST, WI, Federal, CT, MA, NH, VT Tropical soda apple FLEPPC, SEEPPC, SWSS, Federal, AL, AZ, CA, FL, MA, MN, MS, NC, OR, SC, TN, TX, VT Turkey berry FLEPPC, WSWS, Federal, AL, CA, FL, HI, MA, MN, NC, OR, SC, VT West Indian raspberry HEAR, N’EAST Yellow Himalayan raspberry World’s Worst 100, HEAR, N’EAST, HI Trees

Organizations and Federal or State Governments

Australian pine Autumn olive Brazilian peppertree Carrotwood Chinaberry Fire tree Melaleuca

FLEPPC, HEAR, Federal, FL SEEPPC, WI, CT, MA, NH, WV World’s Worst 100, Cal-IPC, FLEPPC, HEAR, FL, TX FLEPPC, FL FLEPPC, SEEPPC, Federal World’s Worst 100, HEAR, HI World’s Worst 100, Federal, AL, CA, FL, MA, NC, OR, SC, TX, VT

PLANT SPECIES LISTED AS INVASIVE n 693 Trees

Organizations and Federal or State Governments

Paper mulberry Princess tree Russian olive Silk tree Strawberry guava Tamarisk species Tree of heaven Velvet tree Woman’s tongue

SEEPPC SEEPPC, Federal, CT Cal-IPC, NE&GP, WI, WSWS, Federal, CO, CT, NM FLEPPC, SEEPPC, Federal World’s Worst 100, FLEPPC, HEAR World’s Worst 100, Cal-IPC, WSWS, Federal, CO, MT, NB, NV, NM, ND, OR, SD, TX, WA, WY Cal-IPC, SEEPC, WI, Federal, CT, MA, NH, VT World’s Worst 100, HEAR, HI FLEPPC, HEAR

Vines

Organizations and Federal or State Governments

Black swallow-wort Chinese wisteria Dodder species

N’EAST, federal, CT, MA, NH, VT SEEPC, PLEPPC, Federal N’EAST, Federal, AL, AZ, AR, CA, FL, MA, MI, MN, NC, OR, SC, SD, TX, VT, WA Cal-IPC, SEEPPC, WI, Federal, OR, WA KY, N’EAST, NE&GP, SWSS, WI, WSWS, Federal, AK, AZ, AR, CA, CO, HI, ID, IA, KS, MI, MN, MO, MT, NM, ND, OR, SD, TX, UT, WA, WI, WY FLEPPC, Federal, AL, FL FLEPPC, HEAR, N’EAST, SEEPPC, SWSS, WI, Federal, CT, MA, NH, VT CT, MA SEEPPC, Federal World’s Worst 100, FLEPPC, HEAR, KY, N’EAST, SEEPPC, SWSS, Federal, CT, FL, IL, KS, KY, MA, MS, MO, OR, PA, TX, WA, WV N’EAST, Federal, AL, CT, MA, NC, OH, PA, SC FLEPPC, Federal, AL, FL N’EAST, SEEPPC, WI, Federal, CT, MA, NH, NC, VT Federal, CT, MA, NH, VT SWSS WI, Federal, CT, MA FLEPPC, Federal, AL, CA, FL, MA, NC, OR, SC, VT Federal, VT SEEPC, WI, Federal

English ivy Field bindweed

Japanese climbing fern Japanese honeysuckle Japanese hops Japanese wisteria Kudzu Mile-a-minute Old World climbing fern Oriental bittersweet Pale swallow-wort Peppervine Porcelainberry Wetlands nightshade White swallow-wort Winter creeper

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Set Appendices

n Appendix A: American Species That Are Invasive Abroad

Many species native to the United States are invasive in other parts of the world. The following presents a sample of those that are having or are expected to have a significant impact on ecosystems and/or economies in the regions to which they have been introduced. The list reflects those regions best studied for exotic species and does not necessarily represent the full nonnative range of a given taxon.

I. Plants Common Name

Scientific Name

Areas Where It Is Invasive

Trees Black cherry Black locust Douglas fir Honey locust Honey mesquite* Loblolly pine Lodgepole pine Monterey pine

Prunus serotina Robinia pseudoacacia Pseudotsuga menzeiseii Gleditsia triacanthus Prosopis glandulosa Pinus taeda Pinus contorta Pinus radiata

Parkinsonia Slash pine Velvet mesquite

Parkinsonia aculeata Pinus elliotti Prosopis velutina

Northwest Europe Europe, Australia, southern Africa Argentina Europe South America, southern Africa, Australia Argentina, Brazil Argentina, Australia, New Zealand Argentina, southern Africa, Australia, New Zealand Australia Brazil, southern Africa, Australia South America, Africa

Shrubs Desert false indigo Oregon grape Sand blackberry

Amorpha fruticosa Mahonia aquifolium Rubus cuneifolius

Southern Europe, temperate Asia Europe Chile, Australia, southern Africa

Forbs Annual ragweed Canada goldenrod Giant goldenrod Jerusalem artichoke

Ambrosia artemisiifolia Solidago canadensis Solidago gigantea Helianthus tuberosa

Europe Europe, temperate Asia Europe Europe (Continued )

696 n APPENDIX A Common Name

Scientific Name

Areas Where It Is Invasive

Large-leaved lupine Rough cocklebur

Lupinus polyphyllus Xanthium strumarium

Europe, New Zealand Southern Africa, Australia

Graminoids Broomsedge bluestem Finestem needlegrass Jointed rush Rice cutgrass Smooth cordgrass Soft rush Tall flatsedge

Andropogon virginicus Nassella tenuissima Juncus articularis Leersia oryzoides Spartina alterniflora Juncus effusus Cyperus eragrostis

Tropical Africa Southern Africa Australia, New Zealand Australia New Zealand Australia Southern Europe, Australia

Succulents Century plant

Agave americana

Erect prickly pear*

Opuntia stricta

Tree cholla

Cylindropuntia imbricata

Southern Europe, southern Africa, Canary Islands, Azores Australia, Madagascar southern Europe, southern Africa, temperate Asia, Southern Africa

Aquatic Plants American water fern American waterweed

Azolla filiculoides Elodea canadensis

Europe Southern Europe, Australia

II. Invertebrates Common Name

Scientific Name

Areas Where It Is Invasive

Trematode American liverfluke

Fuscioloides magna

Europe

Ctenophore Warty comb jelly*

Mnemiopsis leidyi

Black Sea, Mediterranean Sea, North Sea, Baltic Sea

Mollusks American oyster drill Atlantic jackknife clam Bay barnacle Common slipper shell Rosy wolfsnail *

Urosalpinx cinerea Ensis directus Balanus improvisus Crepidula fornicata Euglandia rosea

Northern Europe Northwest Europe Europe Europe Islands of Pacific and Indian oceans

Crustaceans American lobster Louisiana crayfish Signal crayfish Spiny-cheeked crayfish Recluse spiders

Homarus americanus Procambarus clarkii Pacifastacus lenisculus Oronectes limosus Loxosceles spp.

Europe Africa, China, Europe Europe, Japan Europe Europe

Insects Ambrosia beetle American rice water weevil Cypress tip moth Eastern subterranean termite

Gnathotrichus materarius Lissorhoptrus oryzophilus Argyresthia cupressella Reticulitermes flavipes

Europe China Europe Europe

APPENDIX A n 697 Common Name

Scientific Name

Areas Where It Is Invasive

Fall webworm Loblolly pine mealybug Oak lacebug Orange spruce needleminer Sycamore lacebug Western conifer seed bug

Hyphantria cunea Oracella acuta Corythucha arcuata Coleotechnites piceaella Corythucha ciliata Leptoglossus occidentalis

China China Europe Europe Europe Europe

Common Name

Scientific Name

Areas Where It Is Invasive

Fish Black bullhead Brook trout Brown bullhead Channel catfish Fathead minnow Lake trout Largemouth bass * Western mosquitofish* Pumpkinseed sunfish Rainbow trout* Smallmouth bass

Ameiurus melas Salvelinus fontinalis Ameiurus nebulosa Ictalurus punctatus Pimephales promelas Salvelinus namaycush Micropterus salmoides Gambusia affinis Lepomis gibbosus Oncorhynchus mykiss Micropterus dolomieu

Europe Europe Europe, Chile, New Zealand Europe Europe Europe Southern Africa Argentina, China, Europe Europe Argentina Europe

Amphibian American bullfrog*

Lithobates catesbeianus

South America, Asia

Reptile Red-eared slider*

Trachemys scripta

Europe

Birds California Quail Canada Goose Ruddy Duck

Callipepla californica Branta canadenis Oxyura jamaicensis

Chile Europe Europe

Mammals American beaver

Castor canadensis

American mink Eastern cottontail Grey Squirrel * Muskrat

Mustela vison Sylvilagus floridanus Sciurus carolinensis Ondatra zibethicus

Raccoon

Procyon lotor

Tierra del Fuego (Argentina and Chile) Argentina, Chile; Europe Europe Europe China, Europe, South America, Japan Europe

III. Vertebrates

698 n APPENDIX A

IV. Fungi Common Name

Scientific Name

Areas Where It Is Invasive

Crayfish plague* Cypress canker

Aphanomyces astaci Seiridium cardinale

Europe Southern Europe

*Nominated as one of 100 of the world’s worst invading alien species by the Invasive Species Specialist Group.

Sources Global Invasive Species Programme. http://www.gisp.org/index.asp. Hulme, Philip E. Handbook of Alien Species in Europe. Dordrecht, Netherlands: Springer, 2009. http:// dx.doi.org/10.1007/978-1-4020-8280-1. Lowe, S., M. Browne, S. Boudjelas, and M. Poorter. “100 of the World’s Worst Invasive Alien Species. A Selection from the Global Invasive Species Database.” Invasive Species Specialist Group (ISSG) of the Species Survival Commission (SSC) of the World Conservation Union (IUCN), 2004. Electronic version available at http://www.gisp.org/publications/reports/100worst.pdf. U.S. Department of Agriculture, National Invasive Species Information Center, International. http:// www.invasivespeciesinfo.gov/international/main.shtml. Weber, Ewald. Invasive Plant Species of the World: A Reference Guide to Environmental Weeds. Cambridge, MA: CABI Publishing, 2003.

n Appendix B: Major Federal Legislation

and Agreements Pertaining to Invasive Species

1900

Lacey Act (amended 1998) One of the oldest laws pertaining to wildlife in the United States. With its subsequent amendments, it prohibits the importation into the United States of wild mammals, wild birds, reptiles, amphibians, fish, mollusks, and crustaceans that appear on a list of injurious wildlife without a permit issued by the U.S. Fish and Wildlife Service. It also prohibits the transport of such species between states, the District of Columbia, the Commonwealth of Puerto Rico, or any territory or possession of the United States.

1912

Plant Quarantine Act (repealed Jun 20, 2000, with passage of the Plant Protection Act of 2000) Gave the Animal and Plant Health Inspection Service (APHIS) the authority to regulate importation and interstate movement of nursery stock and other plants that may carry harmful pests and diseases. Preempted state quarantines in interstate commerce.

1916

National Park Service Organic Act Promotes the eradication and control of nonindigenous species and prohibits most introduction in national parks.

1931

Animal Damage Control Act Gives APHIS authority to control wildlife damage, including that of nonindigenous species, on federal, state, or private land. Protects field crops, vegetables, fruits, nuts, horticultural crops, commercial forests; freshwater aquaculture ponds and marine species cultivation areas; livestock on public and private range and in feedlots; public and private buildings and facilities; civilian and military aircraft; public health.

1940

Federal Seed Act (amended 1998) Requires accurate labeling and purity standards for seeds in commerce. Prohibits importation and interstate movement of adulterated or misbranded seeds.

1944

Organic Act Gives APHIS the authority to conduct plant pest eradication programs.

1944

Public Health Services Act Regulates entry of living organisms into the U.S. that may carry or cause human diseases.

700 n APPENDIX B 1947

Federal Insecticide, Fungicide, and Rodenticide Act. 7 U.S.C. §136 Gives EPA authority to regulate importation and distribution of substances, including microorganisms that are intended to function as pesticides.

1951

Importation of Certain Mollusks Provides for the inspection and treatment of goods entering the U.S. from areas infested with any terrestrial or freshwater mollusks to control entry of such organisms.

1952

International Plant Protection Convention (IPPC) Creates an international regime to prevent the spread and introduction of plant and plant product pests premised on the exchange of Phytosanitary certificates between importing and exporting countries’ national plant protection offices. Parties have national plant protection organizations established according to the Convention with authority in relation to quarantine control, risk analysis and other measures required to prevent the establishment and spread of all invasive alien species that, directly or indirectly, are pests of plants. Parties agree to cooperate on information exchange and on the development of International Standards for Phytosanitary Measures. Defines pests of plants or plant products as “any form of plant or animal life, or any pathogenic agent, injurious or potentially injurious to plants or plant products.” Provides for quarantine of pests involved with international trade, specifically any “pest of potential national economic importance to the country endangered thereby and not yet present there, or present but not widely distributed and being actively controlled.”

1955

Convention on Great Lakes Fisheries Between the United States and Canada Establishes the Great Lakes Fisheries Commission, whose purpose is to control and eradicate the nonnative, highly invasive Atlantic sea lamprey from the Great Lakes.

1970

National Environmental Policy Act (NEPA). Public Law 91-190 Requires federal government agencies to consider the environmental effects of their actions through preparation of environmental impact statements (EIS). Effects of nonnative species, if harmful to the environment, must be included in the EIS, but APHIS may approve and issue permits for importing nonindigenous species following preparation of an environmental assessment rather than an environmental impact statement. Permits for importing nonindigenous species into containment facilities or interstate movement between containment facilities are excluded from NEPA requirements.

1973

Endangered Species Act When nonnative invasive species threaten endangered species, this act could be used as basis for their eradication.

APPENDIX B n 701

1974

Federal Noxious Weed Act (Secs. 2801 to 2813—repealed; superseded by the Plant Protection Act, except for Sec. 2814) Defines noxious weeds as “any living stage (including, but not limited to, seeds and reproductive parts) of any parasitic or other plant of a kind, or subdivision of a kind, which is of foreign origin, is new to or not widely prevalent in the United States, and can directly or indirectly injure crops, other useful plants, livestock, or poultry or other interests of agriculture, including . . . the fish and wildlife resources of the United States or the public health.” Authorizes APHIS to restrict the introduction and spread of nonnative noxious weeds through port-of-entry and follow-up activities. Authorizes permanent restrictions and emergency regulations.

1975

Convention on International Trade in Endangered Species (CITES) Regulates intentional introductions through trade (export, re-export, import and introduction from the sea) of plants and animals which are threatened or endangered in the exporting countries. Represents an alternate model for regulating invasive species not already covered by the IPPC or other agreements. Although the Convention is intended to prevent harm in exporting country; it can be applied when a species is endangered in the exporting country and considered an invasive in the importing country.

1975

Convention on the prohibition of the development, production, and stockpiling of bacteriological (biological) and toxin weapons and on their destruction (Biological Weapons Convention) While the Convention prohibits parties from developing, producing, stockpiling, acquiring or retaining microbial or other biological agents for hostile purposes, it allows for the “international exchange of bacterial agents and toxins and equipment for the processing, use or production of bacterial agents and toxins for peaceful purposes.” Could lead to the unintentional release of such agents.

1977

Executive Order 11987, Exotic Organisms Restricts the introduction of exotic species into natural ecosystems under federal agency authority.

1978

Cooperative Forestry Assistance Act Provides for detection, identification, surveys, and controls of forest pests.

1980

Act to Prevent Pollution from Ships (amended by the Marine Plastics Pollution Research and Control Act of 1987) Requires ships in U.S. waters to comply with the International Convention for the Prevention of Pollution from Ships.

702 n APPENDIX B 1987

Clean Water Act (as amended in 1987) Allows releases of ballast water to be permitted or otherwise controlled under sections 402 (National Pollution Discharge Elimination System) and 303(d) (Total Maximum Daily Load program).

1990

Agricultural Quarantine Enforcement Act Prohibits shipping of plants, fruits, and vegetables via first-class mail.

1990

Food, Agriculture, Conservation, and Trade Act Establishes Genetic Resources Program to collect, classify, preserve, and disseminate genetic material important to agriculture.

1990

Toxic Substances Control Act Enables EPA to regulate nonindigenous microbes.

1990

Non-indigenous Aquatic Nuisance Prevention and Control Act (NANPCA). Public Law 101-646 Establishes Aquatic Nuisance Species Task Force to identify areas where ballast water does not pose an environmental threat, assess whether aquatic nuisance species threaten the ecological characteristics and economic uses of U.S. waters (other than the Great Lakes), determine the need for controls on vessels entering U.S. waters (other than Great Lakes), identify and evaluate approaches for reducing risk of adverse consequences associated with intentional introduction of aquatic species. Directs Coast Guard to issue regulations to prevent the introduction and spread of aquatic nuisance species into the Great Lakes through ballast water Directs Corps of Engineers to develop a program of research and technology to control zebra mussels in and around public facilities and make available information on control methods

1992

Wild Bird Conservation Act. Public Law 102-440 Regulates importation of foreign wild birds.

1992

Hawaii Tropical Forest Recovery Act. Public Law 102-574 Authorizes Sec. of Agriculture and USFS to establish biological control agents for non-native species. Creates task force to develop action plan to “promote public awareness of the harm caused by introduced species” develop recommendations on “the benefits of fencing or other management activities for the protection of Hawaii’s native plants and animals from non-native species, including the identification and priorities for the areas where these activities are appropriate.”

1992

Alien Species Prevention and Enforcement Act. Public Law 102-393 Makes illegal the shipment through U.S. mail of plants or plant matter whose shipment is prohibited under the Federal Plant Pest Act or Plant Quarantine Act and of animals whose shipment is prohibited under 18 U.S.C. 42; 43, or the Lacey Act.

APPENDIX B n 703

1994

North American Agreement on Environmental Cooperation Article 10 (2)(h) states that the Council of the Commission on Environmental Cooperation may develop recommendations regarding exotic species that may be harmful.

1995

Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement) A supplementary agreement to the World Trade Organization Agreement. Provides a uniform interpretation of the measures governing safety and plant and animal health regulations. Applicable to all sanitary and phytosanitary measures directly or indirectly affecting international trade. Sanitary and phytosanitary measures are defined as any measure applied to protect animal or plant life or health within (a Members’ Territory) from entry, establishment or spread of pests, diseases, disease carrying organisms; and to prevent or limit other damage within the (Members Territory) from the entry, establishment or spread of pests.

1996

National Invasive Species Act. Public Law 104-332 Reauthorizes and amends the Non-indigenous Aquatic Nuisance Prevention and Control Act of 1990. Mandates regulations to prevent introduction and spread of aquatic nuisance species into Great Lakes through ballast water. Authorizes funding for research on aquatic nuisance species prevention and control (Chesapeake Bay, Gulf of Mexico, Pacific Coast, Atlantic Coast, San Francisco Bay–Delta Estuary). Requires ballast water management program to demonstrate technologies and practices to prevent nonindigenous species from being introduced. Modifies composition of Aquatic Nuisance Species Task Force. Requires Task Force to develop and implement comprehensive program to control the brown tree snake in Guam.

1998

Lacey Act (1900; amended in 1998) Prohibits import of a number of designated species and other vertebrates, mollusks, and crustaceans that are “injurious to human beings, to the interests of agriculture, horticulture, forestry, or to wildlife or the wildlife resources of the United States.” Declares importation or transportation of any live wildlife as injurious and prohibited, except as provided for under the Act; but allows import of almost all species for scientific, medical, education, exhibition, or propagation purposes.

1999

Executive Order 13112 on Invasive Species Defines invasive species as “an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health.” Prevents the introduction of invasive species, provides for their control, and reduces impacts through improved coordination of federal agencies under a National Invasive Species Management Plan.

704 n APPENDIX B 1999

Water Resources Development Act. Public Law Public Law 106-53 Authorizes the Secretary of the Interior, in conjunction with the Great Lakes Fishery Commission, to undertake a program for the control of sea lampreys in and around waters of the Great Lakes.

2000

Plant Protection Act. Public Law 106-224 (Replaces the Federal Noxious Weed Act and many other APHIS Plant Protection Authorities) Consolidates and modernizes all major statutes pertaining to plant protection and quarantine (Federal Noxious Weed Act, Plant Quarantine Act). Permits APHIS to address all types of weed issues. Increases maximum civil penalty for violation. Authorizes APHIS to take both emergency and extraordinary emergency actions to address incursions of noxious weeds.

2002

Farm Security and Rural Investment Act. Public Law 107-171 (Animal Health Protection Act) Directs the USDA to take measures ensuring the prevention, detection, control, and eradication of diseases and pests of animals when essential to protect (a) animal health; (b) the health and welfare of the people of the U.S.; (c) the economic interests of the livestock and related industries of the U.S.; (d) the environment of the U.S.; and (e) interstate commerce and foreign commerce of the U.S. in animals and other articles.

2002

Public Health Security and Bioterrorism Preparedness and Response Act. Public Law 107-188 Improves the ability of the United States to prevent, prepare for, and respond to bioterrorism and other public health emergencies. Ensures coordination and minimizing duplication of Federal, State, and local planning, preparedness, and response activities, including during the investigation of a suspicious disease outbreak or other potential public health emergency. Particularly directs attention to invasive pests and pathogens affecting livestock.

2003

Nutria Eradication and Control Act. Public Law 108-016 Authorizes the Secretary of the Interior to provide financial assistance to the State of Maryland and the State of Louisiana for a program to implement measures to eradicate or control nutria and restore marshland damaged by nutria.

2004

Brown Tree Snake Control and Eradication Act. Public Law 108-38 Subject to the availability of appropriated funds for this purpose, authorizes the expansion of research and eradication and control programs in Guam to reduce the impact of the brown tree snake and reduce the risk of its introduction or spread to other areas.

2004

Noxious Weed Control and Eradication Act. Public Law 108-412

APPENDIX B n 705

Establishes a program to provide financial and technical assistance to control or eradicate noxious weeds. Subject to the availability of appropriations under section 457(a), the Secretary of Agriculture shall make grants to weed management entities for the control or eradication of noxious weeds. Subject to the availability of appropriations under section 457(b), the Secretary of Agriculture shall enter into agreements with weed management entities to provide financial and technical assistance for the control or eradication of noxious weeds. 2004

National Plan for Control and Management of Sudden Oak Death. Public Law 108-488 (amends the Plant Protection Act) Subject to the availability of appropriated funds for this purpose, the Secretary of Agriculture, acting through APHIS, shall develop a national plan for the control and management of Sudden Oak Death, a forest disease caused by the funguslike pathogen Phytophthora ramorum.

2005

§6006 of the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU). Public Law 109-59 (implements 23 U.S.C. § 329, a new provision of law added to Title 23 by §6006 of SAFETEA-LU) Includes a provision that makes activities for the control of noxious weeds and the establishment of native species eligible for Federal-aid funds under the National Highway System (NHS) and the Surface Transportation System (STP). The control of terrestrial noxious weeds and aquatic weeds is commonly done by maintenance districts or contracted crews of each State department of transportation. Historically, maintenance activities have been the responsibility of the State and therefore have not been eligible for Federal-aid dollars.

2005

Public Lands Corps Healthy Forests Restoration Act. Public Law 109-154 (amends the Public Lands Corps Act of 1993) Addresses the impact of insect or disease infestations or other damaging agents on forest and rangeland health

2006

Salt Cedar and Russian Olive Control Demonstration Act. Public Law 109-320 Directs the Secretary of the Interior, acting through the Commissioner of Reclamation, to carry out an assessment and demonstration program to control salt cedar and Russian olive, and for other purposes.

2006

Great Lakes Fish and Wildlife Restoration Act of 2006. Public Law 109-326 Amends the Great Lakes Fish and Wildlife Restoration Act of 1990 to provide for implementation of recommendations of the United States Fish and Wildlife Service contained in the Great Lakes Fishery Resources Restoration Study.

2007

Water Resources Development Act of 2007. Public Law 110-114; Sec. 3061 Provides for the conservation and development of water and related resources, to authorize the Secretary of the Army to construct various projects for improvements to rivers and harbors of the United States, and for other purposes, including Asian carp dispersal barrier demonstration project, Upper Mississippi River.

706 n APPENDIX B 2008

National Defense Authorization Act (NDAA) for Fiscal Year (FY) 2008 To prevent the introduction of the brown tree snake into Hawaii, the Commonwealth of the Northern Mariana Islands, the continental United States, or any other non-native environment as a result of the movement from Guam of military aircraft, personnel, and cargo, including the household goods of military personnel and other military assets.

2008

Food, Conservation, and Energy Act of 2008 (The 2008 Farm Bill) (amends the Lacey Act) Amends the Lacey Act to cover a broad range of plants and plant products, including timber deriving from illegally harvested plants.

2009

Public Land Management Act of 2009. Public Law 111-11 Allows the Secretary of the Interior to prescribe measures to control nonnative invasive plants and noxious weeds within the National Wilderness Preservation System.

Bills Relating to Invasive Species before the U.S. Congress The National Invasive Species Center tracks pending legislation at http://www.invasive speciesinfo.gov/laws/federal.shtml. GovTrack.us also allows tracking of legislation, by subject, at http://www.govtrack.us/ congress/legislation.xpd.

Sources “Federal Laws and Regulations. Public Laws and Acts.” National Invasive Species Information Center, U.S. Department of Agriculture, National Agricultural Library, 2010. http://www.invasive speciesinfo.gov/laws/publiclaws.shtml. “An Initial Survey of Aquatic Invasive Species in the Gulf of Mexico Region.” Version 4.0. A report to the Gulf of Mexico Program, U.S. Environmental Protection Agency, EPA/OCPD Contract # 68-C -00-121, Battelle, 2000.

n Appendix C: Selected International Agreements and Conventions Pertaining to Invasive Species

1959

Agreement Concerning Cooperation in the Quarantine of Plants and the Protection against Pests and Diseases Signature parties agree to take measures to prevent the introduction from one country into another of plant pests and diseases and weeds specified in lists drawn up by the parties. (Not ratified by the United States.)

1972

International Plant Protection Convention (IPPC) Creates an international system to prevent the spread and introduction of plant and plant product pests based on the exchange of phytosanitary certificates between importing and exporting countries’ national plant protection offices. Parties have national plant protection organizations established according to the Convention with authority in relation to quarantine control, risk analysis, and other measures required to prevent the establishment and spread of all invasive alien species that, directly or indirectly, are pests of plants. (Ratified by the United States, August 18, 1972.)

1974

Convention of International Trade in Endangered Species (CITES) Offers an alternate method for regulating invasive species not already covered in IPPC or other agreements. Can only be used when the species in question is endangered in the export country and considered invasive in the importing country and the pathway is intentional. (Ratified by the United States, January 14, 1974.)

1979

Convention of Migratory Species of Wild Animals Article III (4)(c): Parties in the range of endangered migratory species can, to the extent feasible and appropriate, take measures to prevent, reduce, or control factors that are endangering or likely to further endanger the species, including strictly controlling the introduction of, or controlling or eliminating already introduced exotic species detrimental to a migrating species. (Not ratified by the United States.)

1982

United Nations Convention on the Law of the Sea (UNCLOS) Signature states will take all measures necessary to prevent, reduce and control the intentional or accidental introduction of species, alien or new, to a particular part

708 n APPENDIX C 1982 (cont.)

of the marine environment, which may cause significant and harmful changes thereto. (Not ratified by the United States.)

1992

Framework Convention of Climate Control Promotes stabilization and eventual reduction of greenhouse gas concentrations in the atmosphere. Relevance to invasive species is that changes in climate could stimulate new invasions and increase the rate or impact of existing invasions. (Ratified by the United States, October 15, 1992.)

1992

Agenda 21, United Nations Conference on Environment and Development (Earth Summit, Rio de Janeiro) A blueprint for action on many fronts where humans affect the natural environment, the program addressed unintentional and intentional introductions of alien plants and animals and ballast water problems.

1992

Convention of Biological Diversity (CBD)/Invasive Alien Species Calls on signature parties, to the degree possible and appropriate, to “prevent the introduction of, control or eradicate those alien species which threaten ecosystems, habitats or species.” (Not ratified by the United States.)

1994

Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement) A supplement to the World Trade Organization Agreement that gives a uniform interpretation of the measures governing safety and plant and animal health regulations that is applied to all measures directly or indirectly affecting international trade. Sanitary and phytosanitary measures are defined as any measure designed to protect animal or plant life or health within a member’s territory from the introduction, establishment or spread of pests, diseases, and diseases carrying organisms. Calls upon members to prevent or limit other damage within their territories from the introduction, establishment, or spread of pests. (The United States became a member of the World Trade Organization in 1995.)

1997

Convention on the Law of Non-navigational Uses of International Watercourses States on international watercourses shall take all necessary steps to prevent the intentional or unintentional introduction of species, alien or new, into an international watercourse which may have effects detrimental to the ecosystem and result in significant harm to other countries on the waterway.

1997

International Maritime Organization Annex. Nonmandatory “Guidelines for the Control and Management of Ships’ Ballast Water to Minimize the Transfer of Harmful Aquatic Organisms and Pathogens.” Among the provisions are (1) recognition that ballast water is “the most prominent” pathway for transferring aquatic organisms that could pose threats to native human, animal, and plant life and the marine environment; and (2) “Every ship

APPENDIX C n 709

that carries ballast water should be provided with a ballast water management plan to assist in the minimization of transfer of harmful aquatic organisms and pathogens.”

Source “International Laws and Regulations,” National Invasive Species Information Center, U.S. Department of Agriculture, National Agricultural Library, 2009. http://www.invasivespeciesinfo.gov/laws/ intlagree.shtml.

n Appendix D: ISSG’s 100 of the World’s Worst Invasive Alien Species

Those shown in bold type are described in entries in this encyclopedia. MICRO-ORGANISM avian malaria (Plasmodium relictum) banana bunchy top virus (Banana bunchy top virus) rinderpest virus1 (Rinderpest virus) MACRO-FUNGI chestnut blight (Cryphonectria parasitica) crayfish plague (Aphanomyces astaci) Dutch elm disease (Ophiostoma ulmi) frog chytrid fungus (Batrachochytrium dendrobatidis) phytophthora root rot (Phytophthora cinnamomi) AQUATIC PLANT caulerpa seaweed (Caulerpa taxifolia) common cord-grass (Spartina anglica) wakame seaweed (Undaria pinnatifida) water hyacinth (Eichhornia crassipes) LAND PLANT African tulip tree (Spathodea campanulata) black wattle (Acacia mearnsii) Brazilian pepper tree (Schinus terebinthifolius) cogongrass (Imperata cylindrica) cluster pine (Pinus pinaster) erect pricklypear (Opuntia stricta) fire tree (Morella faya) giant reed (Arundo donax) gorse (Ulex europaeus) hiptage (Hiptage benghalensis) Japanese knotweed (Fallopia japonica) Kahili ginger (Hedychium gardnerianum) Koster’s curse (Clidemia hirta) kudzu (Pueraria montana var. lobata) lantana (Lantana camara) leafy spurge (Euphorbia esula) leucaena (Leucaena leucocephala) melaleuca (Melaleuca quinquenervia) mesquite (Prosopis glandulosa) miconia (Miconia calvescens) mile-a-minute weed (Mikania micrantha) mimosa (Mimosa pigra) privet (Ligustrum robustum)

APPENDIX D n 711 pumpwood (Cecropia peltata) purple loosestrife (Lythrum salicaria) quinine tree (Cinchona pubescens) shoebutton ardisia (Ardisia elliptica) Siam weed (Chromolaena odorata) strawberry guava (Psidium cattleianum) tamarisk (Tamarix ramosissima) wedelia (Sphagneticola trilobata) yellow Himalayan raspberry (Rubus ellipticus) AQUATIC INVERTEBRATE Chinese mitten crab (Eriocheir sinensis) comb jelly (Mnemiopsis leidyi) fish hook flea (Cercopagis pengoi) golden apple snail (Pomacea canaliculata) green crab (Carcinus maenas) marine clam (Potamocorbula amurensis) Mediterranean mussel (Mytilus galloprovincialis) Northern Pacific seastar (Asterias amurensis) zebra mussel (Dreissena polymorpha) LAND INVERTEBRATE Argentine ant (Linepithema humile) Asian longhorned beetle (Anoplophora glabripennis) Asian tiger mosquito (Aedes albopictus) big-headed ant (Pheidole megacephala) common malaria mosquito (Anopheles quadrimaculatus) common wasp (Vespula vulgaris) crazy ant (Anoplolepis gracilipes) cypress aphid (Cinara cupressi) flatworm (Platydemus manokwari) Formosan subterranean termite (Coptotermes formosanus shiraki) giant African snail (Achatina fulica) gypsy moth (Lymantria dispar) khapra beetle (Trogoderma granarium) little fire ant (Wasmannia auropunctata) red imported fire ant (Solenopsis invicta) rosy wolf snail (Euglandina rosea) sweet potato whitefly (Bemisia tabaci) AMPHIBIAN bullfrog (Rana catesbeiana) cane toad (Bufo marinus) Caribbean tree frog (Eleutherodactylus coqui) FISH brown trout (Salmo trutta) carp (Cyprinus carpio) large-mouth bass (Micropterus salmoides) Mozambique tilapia (Oreochromis mossambicus) Nile perch (Lates niloticus) rainbow trout (Oncorhynchus mykiss) walking catfish (Clarias batrachus) Western mosquito fish (Gambusia affinis) (Continued )

712 n APPENDIX D BIRD Indian myna bird (Acridotheres tristis) red-vented bulbul (Pycnonotus cafer) starling (Sturnus vulgaris) REPTILE brown tree snake (Boiga irregularis) red-eared slider (Trachemys scripta) MAMMALS brushtail possum (Trichosurus vulpecula) domestic cat (Felis catus) goat (Capra hircus) grey squirrel (Sciurus carolinensis) macaque monkey (Macaca fascicularis) mouse (Mus musculus) nutria (Myocastor coypus) pig (Sus scrofa) rabbit (Oryctolagus cuniculus) red deer (Cervus elaphus) red fox (Vulpes vulpes) ship rat (Rattus rattus) small Indian mongoose (Herpestes javanicus) stoat (Mustela erminea) 1

Declared eradicated in 2010.

Source Lowe S., Browne M., Boudjelas S., De Poorter M. 100 of the World’s Worst Invasive Alien Species, A selection from the Global Invasive Species Database. The Invasive Species Specialist Group (ISSG) a specialist group of the Species Survival Commission (SSC) of the World Conservation Union (IUCN), 2002. http://www.issg.org/database/species/reference_files/100English.pdf. (First published as special lift-out in Aliens 12, December 2000. Updated and reprinted version: November 2004.) Used with permission.

n Glossary Achene. A small, dry, hard one-seed fruit. Adventive. Refers to an introduced species that has arrived in a new habitat or environment without the aid of humans and that has not established a self-replacing population. Aeciospore. A fungal spore produced in an aecium. Each spore has two nuclei and is part of a chain of spores. Aecium. The cuplike fruiting body of some rust fungi. Aerenchyma. Pithy respiratory tissue, common in stems of some aquatic plant species. Agnathan. Member of the class Agnatha, the jawless fish. Alate. Winged reproductive adult of a social insect, such as ants and termites. Alien (species). A nonnative species. A species found beyond its normal range limits. Synonyms: exotic, nonindigenous. Allee effect. The consequences of low population density when the presence of too few individuals greatly reduces reproductive success. Alleleopathy. Condition in which one plant or species exudes chemicals that prevent the growth of other plants in the immediate vicinity. Altricial. Refers to recently hatched birds or other newborn animals that have closed eyes and little or no down or fur, and that are unable to leave the nest and therefore must depend upon the parents for food. Anadromous. Refers to fish that spend most of their lives in salt water but ascend freshwater streams to spawn. Anecic. Refers to deep-burrowing earthworms that inhabit the lower layers of the soil. Annelid worm. Any member of the phylum Annelida, the segmented worms. Annual. A plant that germinates from seed, matures, and dies in one season. Apical (snail). The tip of a spiraling shell. Apomictic. Refers to a flower than does not require pollination to produce seed. Aquatic. Refers to a plant growing primarily or entirely in water, either rooted or free-floating. Aril. The fleshy coating around a seed. Arthropod. Member of the phylum Arthropoda, invertebrates with exoskeletons, segmented bodies, and jointed appendages. The phylum includes arachnids, insects, and crustaceans. Ascospore. A type of spore bearing a single copy of each chromosome formed by sexual reproduction in fungi in the Division/Phylum Ascomycetes. Asexual reproduction. The multiplication of individuals without the fusion of gametes. Can occur in fungi and animals through cell splitting, budding, cloning, or sporation. In plants, formation of new plants without the transfer of pollen. In some plants, new individuals can be generated vegetatively from parts of the parent plant. Auricle. Earlike appendage at the base of some leaves, which clasps the stem.

714 n GLOSSARY Awn. A bristle-shaped appendage on a grass. Axis. The central line of any organ, such as a stem. Barbel. Whiskerlike tactile organ in catfish and carp that houses taste glands and helps them to find food in murky water. Basidiospore. A spore bearing a single copy of each chromosome and found in fungi of the Division/Phylum Basidiomycetes. Beak (bivalve). The highest raised part of each valve, which is generally pointed and located near the hinge. Benthos. A collective term referring to organisms living on the seabed. Bergmann’s Rule. An ecogeographic pattern wherein the higher the latitude or colder the climate, the larger the body size of warmed-blooded animals compared to close relatives living at lower latitudes and/or in warmer climates. Biennial. A plant that lives for two years, usually flowering and setting seed in the second year. Bilabiate. Refers to a corolla, two-lipped. Biodiversity. The total variation and variability of life found in genes, species, communities, ecosystems, and landscapes. Biogeography. The science that studies the distribution patterns of species and the processes that determine those patterns. Biotype. A subset of a species with a particular set of genetic features. Bivalve. A mollusk, such as a clam or mussel, that has its body covered by two rigid shells joined by a hinge. Blade. The portion of the leaf that extends from the leaf sheath, flat, folded, or with rolled margins. Bolt: Rapid growth of flower stalk. Bract. A small scale-like leaf, usually associated with a flower. Bulbil. Small bulb, usually growing from leaf axils. Byssal threads. Filaments that some mollusks produce and use to fasten themselves to hard surfaces. Calyx. The leaf-like sepals that enclose the petals of a flower. Canker. A localized area of dead tissue on the trunk or branch of a woody plant. Cardinal teeth (bivalve). Ridges and grooves on the inner surfaces of both valves of a bivalve near the front end of the hinge that help hold the shells in alignment. Carton. Material made of undigested cellulose, mud, and termite saliva. Catadromous. Refers to fish that spend most of their lives in freshwater but migrate to the sea to breed. Chasmogamous. Refers to flowers that open to allow cross-pollination. Chitin. A strong, semitransparent, horny substance that is the main material composing the exoskeletons of arthropods and the internal structures of certain other invertebrates. Chlamydospore. Large, thick-walled resting spore of several kinds of certain fungi. It is the part of the life cycle that allows survival during unfavorable conditions, such as excessive drought or heat.

GLOSSARY n 715

Cilia. Hairlike structures used by some cells to move themselves or to move food particles. Clambering. Refers to shrubs or vines with stems that climb onto and over other plants. Cleistogamous. Refers to flowers that do not open and are self-pollinated as buds. Clitellum. Thickened, saddlelike section of the body of earthworms that secretes a viscous fluid in which the worm’s eggs are deposited. Colubrid. Any snake of the large and poorly defined group of nonvenomous snakes placed in the family Colubridae. Columella (snail). The central structural spine of coiled snail and whelk shells. Community (ecological). All species living in the same area or a subset of them, such as the bird community or the plant community. Compound. Refers to leaves that are divided into leaflets. Conidia. Asexual, nonmotile spores of a fungus such as chestnut blight. Contact: Refers to herbicides that kill only the plant portions contacted. Coppicing. Refers to trees that sprout many shoots from a cut stump. Corm. A type of bulb. Corolla. The petals of a flower. Corona. A distinct circular growth between the corolla and the stamens, especially in the milkweed family. Culm. Stem of a grass, usually hollow. Cuticle (insect). The exoskeleton, composed mostly of chitin. Cuticle (plant). A protective waxy coating produced by the outermost cells of a leaf or other aerial part of a plant. Cyme. A broad and flat-topped determinate flower cluster, with central flowers opening first. DBH (Diameter at breast height). Standard way of expressing the diameter of a living tree. There is no universal standard, however, as to what breast height is. In the United States, DBH is usually measured at a height of 1.4 m (about 4.5 ft.) above ground. Decumbent. Refers to a stem that is reclining or lying on the ground, but with the tip upright. Dehiscent. Refers to a seed capsule that opens, sometimes explosively. Determinate. Refers to when a branch or stem ceases to grow after flowering. Detritus. Organic debris composed of parts of plants, the remains of animals, and waste products that accumulates on the ground or moves into water bodies from surrounding terrestrial areas. Diapause. A suspension of development in response to adverse environmental conditions. Dioecious. Refers to male and female flowers being on different plants. Disjunct. A distribution pattern in which parts of the range are noncontiguous, i.e., separated geographically. Drupe. A fleshy, one-seeded fruit. Druplet is one part of a berry fruit. Ecology. The interrelationships among organisms and the nonliving aspects of the environment in which they live; the science that studies such interrelationships.

716 n GLOSSARY Ecosystem. The totality of living and nonliving elements in a given area that function as a unit to cycle nutrients and maintain a flow of energy. Ecotype. A population that is adapted to a particular environment and displays characteristics that set it apart from related populations but that has not evolved into a distinct species. Emergent: Refers to aquatic plants that grow primarily above the water surface. Entire. Refers to leaf margins that are smooth, not toothed or serrated. Epiphyte. A plant that physically lives on another but obtains no nutrients from the host. Bromeliads and tropical orchids are frequently epiphytic.The leaves of some epiphytic bromeliads fuse to form a tank in which water collects, creating prime breeding grounds for mosquitoes and some treefrogs. Erect: Growing upright, not sprawling or trailing. Established (species). A species not native to a geographic area and with a self-replacing population. Exotic (species). Any nonnative species. Synonyms: alien, nonnative, nonindigenous. Fasciated: Abnormal growth of a plant part, such as an inflorescence, causing it to be twisted or incurved. Also called crested. Floret. The individual flower of a grass, comprised of two bracts, the lemma and the palea, and the pistil and stamens. Also the individual flower of a composite. Follicle. A dry, dehiscent fruit or seed pod that splits open on the front. Forb. A broad-leaved, green-stemmed, nonwoody plant. One type of herb. Fouling (organism). Any organism that accumulates on solid surfaces in an aquatic environment and impedes the normal mechanical functioning of the equipment or host on which it resides. Frass. Fine, powdery material that wood-eating insects produce as waste after digesting plant matter. Fruiting body. Multicellular structure of fungi that carries spore-forming bodies. When the sexual stages of the life cycle are aerial, they are usually visible to the naked eye. Gamete. A mature sexual reproductive cell, either sperm, pollen, or egg, that fuses with another cell during fertilization to form a new organism. Genotype. The total complement of genes in an individual or an entire species. Gill rakes. Bony or cartilaginous, finger-like projections off the gill arch of fish that allow filter-feeders to retain food particles and keep solids from entering the gill cavity. Also called gill rakers. Glabrous: Smooth; not rough, fuzzy, or hairy. Glaucous. Covered with a bloom, a whitish substance that rubs off. Gloger’s Rule. An ecogeographic pattern in which warm-blooded animals in humid environments tend to have darker pigments in skin, feathers, or hair than close relatives living in drier environments. Glume. Bract on a grass that does not have associated flowers. Gonopodium. An anal fin that on some male live-bearing fish has been modified to allow passage of sperm and internal fertilization. Graminoid. Herbaceous plant that includes grasses, reeds, rushes, and sedges.

GLOSSARY n 717

Granivorous. Feeding on seeds. Gravid. Refers to a female carrying eggs or developing young; pregnant. Habitat. The place in which an organism lives and the physical attributes of that place. Halophyte. Plants adapted to salty conditions. Hammock. Slightly raised tree islands surrounded by other vegetation, usually sawgrass, in the Everglades. Harborage (insects). Shelter or refuge. Haustoria. The root-like, absorbing organs of a parasitic plant. Herb. A plant with no persistent woody stem above ground. Herbaceous. Hibernaculum. The wintering place that shelters hibernating bats. Holoparasite. A parasitic plant that can obtain nutrients and water in no way other than from a host plant. Host specific. Refers to a biological control that affects only the intended plant. Hyphae. Long, branching threads that are the main vegetative structural feature of many fungi. See also Mycelium. Indehiscent. Refers to a fruit that does not split open at maturity to release seeds. Indeterminate. Refers to when a branch or stem continues to grow after flowering. Inflorescence. Flower stalk and how the flowers are arranged. Injurious wildlife. Species of wild mammals, wild birds, fish, mollusks, crustaceans, amphibians, and reptiles listed under the auspices of the Lacey Act that the secretary of the interior has determined may be harmful to the health and welfare of humans; the interests of agriculture, horticulture, or forestry; and the welfare and survival of wildlife resources of the United States. Such species require a permit in order to be imported or transported between states. Instar. A developmental stage in larval insects that begins and ends with a molt until the individual is sexually mature. Often, but not always, morphological changes occur from one instar to the next. Introduced species. A species that has been transported, either deliberately or unintentionally, by humans to a location it had not previously occupied. Introduction. The transport and release into a free-living state of a nonnative species. Invasive species. (1) A nonnative species that is currently spreading rapidly or that has done so in the past; (2) “An alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health” (Executive Order 13112). Involucre. Whorl of small leaves or bracts beneath a flower or flower cluster, especially thistles. Irruption. A sudden, rapid increase in numbers in an animal population, usually accompanied by the migration of many individuals. Keratin. A fibrous structural material composed of protein in skin, hair, nails, feathers, and beaks of vertebrates. Lateral line. A sense organ in aquatic organisms such as fish and amphibians that is used to detect movement and vibration. Commonly visible as a faint line running lengthwise down each side.

718 n GLOSSARY Lateral teeth (bivalve). Elongated, interlocking projections along the hinge line of a shell that prevent the two valves from sliding against each other when the shell is closed. Lemma. The lower of the two bracts that enclose the flower in a grass. Lenticel. Corky cells in the bark of trees that allow air to penetrate into the interior. Ligule. Ring on the inside of a grass leaf where the blade meets the sheath. Lore (bird). The area between the eye and the bill on the side of the head Macroalgae. Large, multicellular algae. Seaweed. Macrophyte. Any plant large enough to be visible to the naked eye. Margins. The edges of leaves or leaflets. Membranous. Thin, parchment-like texture. Meristem. The growing point of a plant. Monocarpic. Refers to a plant in which the growing point of the plant becomes the flowering stem, and the plant dies after flowering. Monoecious. Refers to both female and male flowers on the same plant. Monospecific. Consisting of one species. Monotypic. Consisting of one genotype or ecotype, such as a clone. Mucilaginous. Soft, moist, sticky, or gel-like. Mycelium. A mass of branching, filamentous hyphae through which a fungus absorbs nutrients and decomposes plant material. Naı¨ve. Previously unexposed to a pathogen and therefore having no natural immunity. Native. In this encyclopedia, describes species, habitats, or ecosystems known to have existed in North America prior to European colonization. Considered by many to be the natural elements of a continent’s biodiversity that would occur even if humans had not settled the region. Native transplant. A species that is native to the country or region in question but has been transported beyond its natural range limits. Naturalized (species). Refers to a nonindigenous species that is able to sustain itself reproductively in the wild outside of cultivation, and has become a functioning member of a native ecosystem. Nitrogen fixer. A plant that, with the help of certain soil bacteria that form nodules on its roots, can utilize atmospheric nitrogen. Node. Joint in a stem, usually where the leaves grow. Nonindigenous (species). A species that is not native to the place in which it now occurs. Nonnative (species). An alien, exotic, or nonindigenous species. Noxious (weed). A plant specified by law as being especially undesirable, troublesome, and difficult to control. Nuisance (species). According to the Nonindigenous Nuisance Aquatic Prevention and Control Act of 1990, an alien aquatic species that “threatens the diversity or abundance of native species or the ecological stability of infested waters, or commercial, agricultural or recreational activities dependent upon such waters.”

GLOSSARY n 719

Nymph (insect). The immature form of insects that undergo a gradual and incomplete metamorphosis before reaching the adult stage. A nymph resembles the adult form and never enters a pupal stage. It becomes an adult after the final molt. Opercle. A bony plate that supports the gill covers of fishes, especially the most posterior one. Organelle. Any of the distinct structures within a cell that performs a specific and vital function. Outcompete. When a plant or animal displaces another plant or animal by being a better competitor for some resource. Palate (plant). A bulge in the lower lip of a figwort (Scrophulariaceae) flower that closes off the throat. Palea. The upper of the two bracts that enclose the flower in a grass. Palpus. A jointed organ for touching or tasting attached to a mouthpart in arthropods. Panicle. A loose, irregularly compound inflorescence with flowers on pedicels. Pantropical. Found throughout the tropics. Pappus. Appendage to a flower in the sunflower family (Asteraceaceae), such as a thistle, which may remain attached to the fruit; may be bristled, plume-like, or scaly. Paradioecious. Refers to male and female flowers occurring on separate plants, but any individual can develop flowers of either gender. Parietal callus. In some snails, a thickened deposit on the margin of the aperture and the wall of the body whorl closest to the central spine (columella). It is often smooth and glossy and may be adorned with raised ribs or wrinkles. Parthenogenesis. A form of asexual reproduction in which growth and development of embryos occurs without fertilization of the ovum by sperm. Pathway. The means by which a species arrives at a new region. Pedicel. Stalk that supports an individual flower or fruit. Peduncle. Stalk that supports a flower cluster. Perennial. A plant that lives for more than one season, although aerial parts may die back. Perigynium. The inflated sac, which encloses the ovary in Carex species. Petiole. A leaf stalk. pH. The measure of acidity or alkalinity of soil or water. Using a logarithmic scale, it describes the amount of hydrogen ions in the solution. Pharyngeal teeth (fish). Teeth in the throat located at the back of a fish’s head. Pheromone. Chemicals released by an organism into its environment to communicate with other members of its own species. Some pheromones are alarm signals, while others attract individuals to food or to a mate. Phloem. Plant tissues that conduct foods made in the leaves to all other parts of the plant. Photoperiod. The number of hours of daylight. Phreatophyte. Refers to plants with roots that extend into the water table. Phytoplankter. A tiny, usually microscopic plant that is part of the plankton.

720 n GLOSSARY Pinna. The primary division, or branch, of a pinnate leaf. Leaflets are on the pinna. Plural, pinnae. Pinnate. Refers to compound leaves that have pairs of leaflets on either side of a stalk. Evenly pinnate leaves have an even number of paired leaflets and terminate in a pair. Oddly pinnate leaves have an uneven number of leaflets and terminate in a single leaflet. Pinnatifid. Refers to leaves that resemble pinnately compound leaves, but with lobes that do not reach the midrib of the leaf. Plankton. A collective term referring to all organisms that drift in open water unable to move under their own power against tides and currents. Pollard. Refers to the method of severely pruning tree limbs back to the trunk or to a main branch. Polychaete. A member of the Polychaete class of annelid worms characterized by having bristles on each body segment. Also called bristle worms and lugworms. Postemergent. Refers to a herbicide that affects growing plants. Precocial. Referring to hatchlings or newborns that are born with their eyes open, fully feathered, or furred, and that leave the nest a short time after birth or hatching, Preemergent. Refers to a herbicide that prevents seeds from germinating. Pronotum. In insects, the upper surface of the first segment of the thorax. Propagule. In animals, the minimum number of individuals of a species capable of colonizing a new area. This may be fertilized eggs, a mated female, a single male and a single female, or a whole group of organisms, depending upon the biological and behavioral requirements of the species. In plants, a propagule is whatever structure functions to reproduce the species, such as a seed, spore, stem, or root cutting, Protist. A microorganism that is either single-celled or multicellular, but lacking specialized tissues, and has the genetic information carried in a cell nucleus. Pubescence. Describes plant parts covered with soft, fine hairs. Pupa. In the development of those insects that undergo complete metamorphosis, the life stage that immediately precedes the adult stage. Some pupae remain inside the exoskeleton of the final larval instar, but others are encased in a cocoon or chrysalis. Pustule. A blister-like spot. Pycnia. A flask-shaped or conical fruiting body of a rust fungus that develops below the epidermis of the host and bears pycniospores. Pycniospore. A spore produced in a pycnia of a rust fungus. It fuses with a hypha of the opposite mating type to produce the sexual generation. Raceme. Inflorescence with all the individual flowers on a single axis. Rachilla. A small or secondary axis or rachis, especially the axis that bears florets in sedges and grasses. Rachis. An axis bearing flowers or leaflets. Recurved. Bent backward. Rhizoid (fungi). A structure that functions like a root to anchor the fungus and absorb nutrients. Rhizoid also releases enzymes that break down organic matter.

GLOSSARY n 721

Rhizome. A root structure below the soil surface, distinguished from a root by having nodes; can grow shoots that produce new plants. Also called a rootstock. Rootcrown. Top portion of a root, often containing dormant buds that sprout. Rosette. Arrangement of leaves radiating from a central point. Ruderal. Waste places. Samara. An indehiscent winged fruit. Saprotroph. Any organism that gains energy and nutrients from dead organic material. Savanna. Grassland with scattered trees. Scrambling. Sprawling or climbing over other plants. Sebaceous gland. A gland in the skin that secretes an oily substance to lubricate the skin and hair. Semievergreen. Remaining green only in warm climates or sheltered locations. Senesce. To grow old, turn brown. Senescence. Sepal. A leaf-like bract that encloses a flower or flower bud. Sepals form the calyx. Sessile (plant). Refers to flowers or leaves attached directly to stems, without pedicels or petioles. Settle (mollusks and crustaceans). The process by which larvae leave the plankton stage of their life and attach to a substrate. Sexual reproduction. The formation of new individuals from the union of two gametes, an ovum and a sperm. In the higher plants it takes places with the transfer of pollen from a male flower to a female flower. Sheath. A leaf structure that surrounds and encloses a grass stem. Shrub. Woody perennial smaller than a tree, usually with several stems. Silicle. A small seed pod in the Mustard family. Silique. A seed pod in the Mustard family. Simple. Refers to leaves that are not divided or compound. Species. A group of individuals of the same kind that can interbreed and produce viable offspring. Spike. A simple inflorescence with sessile flowers on a single axis. Also branch of a grass inflorescence. Spikelet. Secondary spike, especially a grass structure that includes glumes and florets, the cluster of grass flowers. Spirochete. A bacterium of the phylum Spirochaete, distinguished by its spirally twisted form. Sporangium. Structure in which spores are formed; spore case. Plural, sporangia. Sporation. Spore formation. Stellate. Refers to plant hairs, star-shaped. Stipule. The basal appendage of a petiole. Stolon. Root stem on the soil surface that roots at nodes; may produce new plants from sprouts; also called runners. Stromata. The connective tissue framework or support of cells or organisms

722 n GLOSSARY Subdioecious. Male and female flowers usually restricted to separate plants. Submergent. Refers to aquatic plants, or parts, that grow completely underwater. Submersed. Refers to aquatic plants that grow primarily underwater. Flowering parts may be at or slightly above the water surface. May be free-floating or rooted. Subshrub. A shrub in which the upper branches die back during the unfavorable seasons. Substrate. Substance in which plants are rooted; can be soil, sand, alluvium, mud, or rock. Surfactant. Substance added to a herbicide to help the chemicals adhere to the foliage. Systemic. Refers to herbicides that are absorbed into plant tissues and translocated throughout the plant. Talus. Cone- or fan-shaped slope of loose rocks at the base of a cliff. Telium. The pimplelike cluster of spore cases that is produced by rust fungi. Ternate. In sets of three. Thorax (insects). The central of three main segments of an insect’s body: the segment between the head and the abdomen. Tree. A woody plant with one main trunk. Turion. A scaly, young shoot or sucker on a root or tuber. Two-ranked. Referring to alternate arrangement of leaves; leaves are on opposite sides of the stem, in the same geometric plane. Umbel. Often flat-topped inflorescence resembling an umbrella, with individual pedicels rising from a common point. Uredinia. A reddish, pimplelike structure on the tissue of a plant infected by a rust fungus. Vegetative reproduction. Formation of new plants from pieces of the parent plant, such as stems, leaves, rhizomes, and stolons. Also called asexual reproduction. Vent (reptile). Cloaca. The common cavity into which the intestinal, genital, and urinary tracts end. Vine. Plant whose stem requires support; can be trailing on the ground or climbing by twining, tendrils, or other means. Whorl. Arrangement of leaves in a circle around the stem, three or more leaves at one node. Xylem. Tissue that conducts water and dissolved minerals from the roots to all other parts of a plant, provides mechanical support, and forms the wood of trees and shrubs. Zooanthellae. Protozoans that live symbiotically in some jellyfishes as well as corals and other marine organisms. Zooid. One of the individual organisms composing a colonial animal, such as a bryozoan. Zooplankter. Any animal, single-celled or multicelled, that is part of the plankton. Zoospore. An asexual spore produced by some fungi that can move around by using a tail-like appendage (flagellum). Zygomorphic. In plants, irregular corollas that can be equally divided into mirror-image halves in only one plane, such as pea or orchid flowers.

n General Bibliography: Selected Classic and Contemporary Works and Major Internet Data Sources

Alien Plant Working Group, Plant Conservation Alliance. “Weeds Gone Wild, Alien Plant Invaders of Natural Areas.” http://www.nps.gov/plants/alien. Animal Diversity Web, University of Michigan Museum of Zoology. http://animaldiversity.ummz .umich.edu/site/index.html. Bargeron, Charles T., David J. Moorhead, G. Keith Douce, Richard C. Reardon, and Arthur E. Miller. Invasive Plants of the Eastern United States: Identification and Control. USDA Forest Service Publication FHTET-2003-08, 2003. http://www.invasive.org/eastern/. Baskins, Yvonne. A Plague of Rats and Rubbervines. The Growing Threat of Species Invasions. Washington, DC: Island Press, 2002. Bossard, Carla C., John M. Randall, and Marc C. Hoshovsky, eds. Invasive Plants of California’s Wildlands. Berkeley: University of California Press, 2000. http://www.cal-ipc.org/ip/management/ ipcw. Burnham, R. J. Plant Diversity Website. CLIMBERS Website, 2010. http://www-personal.umich.edu/ ~rburnham/climbers.html. Burrell, C. Colston. Native Alternatives to Invasive Plants. New York: Brooklyn Botanic Garden, 2006. Cadotte, Marc William, Sean M. McMahon, and Tadashi Fukami. Conceptual Ecology and Invasion Biology: Reciprocal Approaches to Nature. Invading Nature, vol. 1. Dordrecht: Springer, 2006. California Department of Food and Agriculture. Pest Plant and Health Prevention Services (PPHPS). http://www.cdfa.ca.gov/phpps/. Center for Aquatic and Invasive Plants. University of Florida. http://plants.ifas.ufl.edu/. Center for Invasive Species and Ecosystem Health, University of Georgia. http://www.invasive.org/. Center for Invasive Weed Management (CIPM). Missouri River Watershed Coalition. http:// www.weedcenter.org/index.html. Coates, Peter. American Perceptions of Immigrant and Invasive Species. Strangers on the Land. Berkeley: University of California Press, 2006. Cox, G. W. Alien Species in North America and Hawaii: Impacts on Natural Systems. Washington, DC: Island Press, 1999. Elton, Charles S. The Ecology of Invasions by Animals and Plants. London: Chapman and Hall, 1958. Federal Noxious Weed Act of 1974. 7 U.S.C. §§ 2801–2814, January 3, 1975, as amended 1988 and 1994. http://www.thecre.com/fedlaw/legal2/fedweed.htm. “Florida Invaders Series.” Entomology and Nematology Department, Cooperative Extension Sevice, Institute of Food and Agricultural Sciences (IFAS), University of Florida. http:// entnemdept.ifas.ufl.edu/creatures/. Introduced Species Summary Project, Columbia University. http://www.columbia.edu/itc/cerc/danoff -burg/invasion_bio/inv_spp_summ/invbio_plan_report_home.html. Invasispedia. http://wiki.bugwood.org/Invasipedia. “Invasive and Exotic Species of North America.” Invasive.org: Center for Invasive Species and Ecosystem Health, University of Georgia, Warnell School of Forestry and Natural Resources and College of Agricultural and Environmental Sciences, Department of Entomology. http:// www.invasives.org. Invasive Plant Atlas of New England (IPANE). http://nbii-nin.ciesin.columbia.edu/ipane. Invasive Plant Atlas of the United States. http://www.invasiveplantatlas.org.

724 n GENERAL BIBLIOGRAPHY Invasive Plant Information. State and Provinces Weed Lists. Center for Invasive Plant Management (CIPM). http://www.weedcenter.org/inv_plant_info/state.html. “Invasive Species.” Upper Midwest Environmental Sciences Center, U.S. Geological Survey. http:// www.umesc.usgs.gov/invasive_species.html. “Invasive Species Program.” Great Lakes Science Center, U.S. Geological Survey. http:// www.glsc.usgs.gov/main.php?content=research_invasive&title=Invasive% 20Species0&menu=research. Invasive Species Specialist Group (ISSG). “The Global Invasive Species Database.” International Union for Conservation of Nature (IUCN) Species Survival Commission, Global Invasive Species Programme (GISP). http://www.issg.org/database/welcome. Laycock, George. The Alien Animals: The Story of Imported Wildlife. New York: Ballantine Books, 1966. Lockwood, Julie L., Martha F. Hoopes, and Michael P. Marchetti. Invasion Ecology. Oxford: Blackwell Publishing, 2007. McNeely, Jeffrey A. The Great Reshuffling. Human Dimensions of Invasive Alien Species. Gland, Switzerland: IUCN–The World Conservation Union, 2001. Miller, James H., Erwin B. Chambliss, and Nancy J. Lowenstein. A Field Guide for the Identification of Invasive Plants in Southern Forests. Gen. Tech. Rep. SRS-119. USDA Forest Service, Southern Research Station. Ashville, NC. 2010. http://www.srs.fs.usda.gov/pubs/35292. Miller, James H., Steven T. Manning, and Stephen F. Enloe. A Management Guide for Invasive Plants in Southern Forests. Gen. Tech. Rep. SRS-131. USDA Forest Service, Southern Research Station, Ashville, NC. 2010. http://www.srs.fs.usda.gov/pubs/35292. Mooney, H. A., and J. A. Drake, eds. Ecology of Biological Invasions of North America and Hawaii. Ecological Studies 58. New York: Springer-Verlag, 1986. Mooney, Harold A., and Richard J. Hobbs. Invasive Species in a Changing World. Washington, DC: Island Press, 2000. Motooka, P., L. Castro, D. Nelson, G. Nagai, and L. Ching. 2003. Weeds of Hawaii’s Pastures and Natural Areas: An Identification and Management Guide. College of Tropical Agriculture and Human Resources. University of Hawai’i at Manoa. http://www.ctahr.hawaii.edu/invweed/weedsHi.html. National Association of Exotic Pest Plant Councils (NAEPPC). http://www.naeppc.org/. “Non-Native and Invasive Species.” Smithsonian Marine Station at Fort Pierce, FL. http:// www.sms.si.edu; http://www.sms.si.edu/irlspec/Nonnatives.htm. “Non-Native Species” Florida Fish and Wildlife Conservation Commission, Tallahossee. http:// myfwc/wildlifehabitats/nonnatives. Old, Richard. “1,200 Weeds of the 48 States and Adjacent Canada, An> Interactive Identification Guide.” XID Services, Inc. 2008. OTA (Office of Technology Assessment), U.S. Congress. Harmful Nonindigenous Species in the United States. Washington DC, 1993. Pimentel, D., L. Lach, R. Zuniga, and D. Morrison. “Environmental and Economic Costs Associated with Non-Indigenous Species in the United States.” Ithaca, NY: College of Agriculture and Life Sciences, Cornell University, 1999. Plant Conservation Alliance. http://www.nps.gov/plants/index.htm. Plants for a Future, Edible, Medicinal, and Useful Plants for a Healthier World. http://www.pfaf.org/. PlantWise, Garden Smart. http://www.beplantwise.org. Randal, John M., and Janet Marinelli, eds. Invasive Plants, Weeds of the Global Garden. New York: Brooklyn Botanic Garden, 1996. Richardson, David M., Petr Pysˇek, Marcel Rejma´nek, Michael G. Barbour, F. Dane Panetta, and Carol J. West. “Naturalization and Invasion of Alien Plants: Concepts and Definitions.” Diversity and Distributions 6: 93–107, 2000. Ruiz, Gregory. M., and James T. Carlton. Invasive Species: Vector and Management Strategies. Washington, DC: Island Press, 2003. Sax, Dov F., John J. Stachowicz, and Steven D. Gaines. Species Invasions. Insights into Ecology, Evolution, and Biogeography. Sunderland, MA: Sinauer Associates, Inc., 2005. Simberloff, Daniel. “Confronting Introduced Species: A Form of Xenophobia?” Biological Invasions 5: 179–192, 2003.

GENERAL BIBLIOGRAPHY n 725 Southeast Exotic Pest Plant Council Invasive Plant Manual. SEEPPC. http://www.se-eppc.org/manual/. “Species of Concern.” United States Federal Aquatic Nuisance Species Task Force. http:// www.anstaskforce.gov/soc.php. Swearingen, J., K. Reshetiloff, B. Slattery, and S. Zwicker. Plant Invaders of Mid-Atlantic Natural Areas. National Park Service and U.S. Fish and Wildlife Service, 2002. http://www.invasive.org/eastern/ midatlantic/. Todd, Kim. Tinkering with Eden: A Natural History of Exotics in America. New York: W. W. Norton, 2001. U.S. Department of Agriculture, Agriculture Research Service, National Genetic Resources Program. Germplasm Resources Information Network—(GRIN). National Germplasm Resources Laboratory, Beltsville, Maryland.http://www.ars-grin.gov/cgi-bin/npgs/html/index.pl. U.S. Department of Agriculture. Animal and Plant Health and Inspection Service (APHIS). http:// www.aphis.usda.gov/plant_health/plant_pest_info/pest_detection/index.shtml. U.S. Department of Agriculture. Fire Effects Information System. Rocky Mountain Research Station, Fire Sciences Laboratory, 2008. http://www.fs.fed.us/database/feis/. U.S. Department of Agriculture, Forest Service, Invasive Species Program. http://www.fs.fed.us/invasivespecies/index.shtml. U.S. Department of Agriculture, National Invasive Species Information Center (NISIC). http:// www.invasivespeciesinfo.gov/. U.S. Department of Agriculture, Natural Resources Conservation Service. Plants Database. http:// plants.usda.gov/. U.S. Department of Agriculture, Natural Resources Conservation Service. Plants Database. “Invasive and Noxious Weeds.” http://plants.usda.gov/java/noxComposite. U.S. Department of Agriculture, Natural Resources Conservation Service. Plants Database. Plants Profile. http://plants.usda.gov/java/nameSearch. U.S. Geological Survey. Nonindigenous Aquatic Species Database, Gainesville, FL. http:// nas.er.usgs.gov. Van Driesche, R., B. Blossey, M. Hoodle, S. Lyon, and R. Reardon. Biological Control of Invasive Plants in the Eastern United States. USDA Forest Service Publication FHTET-2002-04, 2002. http:// wiki.bugwood.org/Archive:BCIPEUS. Virginia Cooperative Extension. Virginia Tech Weed Identification Guide. http://www.ppws.vt.edu/ weedindex.htm. Vitousek, P. M., C. M. D’Antonio, L. L. Loope, and R. Westbrook. “Biological Invasions as Global Environmental Change.” American Scientist 84: 468–478, 1996. Weber, Ewald. 2003. Invasive Plant Species of the World: A Reference Guide to Environmental Weeds. Cambridge, MA: CABI Publishing, 2003. Zheng, Hao, Yun Wu, Jianquing Ding, Denise Binion, Weidong Fu, and Richard Reardon. 2004. Invasive Plants of Asian Origin Established in the US and Their Natural Enemies, vol. 1, 2004. http:// www.invasive.org/weeds/asian.

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n Index Page numbers in boldfaced type refer to a main entry in the encyclopedia and “t” indicates table. Acarapis woodi. See Honeybee Tracheal Mite Acclimatization societies, 238, 245 Acentria ephemerella, biological control (plants) Eurasian watermilfoil, 324–25 Aceria imperata, biological control (plants) cogongrass, 447 Aceria malherbae, biological control (plants) field bindweed, 609 Aceria salsolae, biological control (plants) prickly Russian thistle, 413 Achatina fulica. See Giant African Snail Acidotheres tristis. See Common Myna Acremonium zonaatum, biological control (plants) waterhyacinth, 342–43 Adedarach species. See Chinaberry Adelges tsugae. See Hemlock Woolly Adelgid Adoretus sinicus. See Chinese rose beetle Adventive species, xiv (v. 1) Aecidium mori var. broussonetia, biological control (plants) paper mulberry, 564 Aedes albopictus. See Asian Tiger Mosquito Aedes eagypti. See Yellow fever mosquito Aegopodium podagraria. See Goutweed African Clawed Frog, xxivt (v. 1), xxvt (v. 1), 18, 19, 201–5 state-by-state occurrences, 295, 296 African feathergrass, 460–61 noxious designation, 653, 665, 666, 668, 669, 670, 671, 691 African fountain grass. See Crimson Fountain Grass African foxtail grass. See Buffelgrass Africanized Honey Bee, xix (v. 1), xxvt (v. 1), 106–10 as varroa mite host, 103, 108 African pyle. See Giant Salvinia Agonopterix nervosa, biological control (plants) brooms, 501 Agreement on the Application of Sanitary and Phytosanitary Measures, 703 Agrilus aurichalceus. See rose stemgirdler Agrilus hyperici, biological control (plants) common St. Johnswort, 361

Agrilus planipennis. See Emerald Ash Borer Agropyron repens. See Quackgrass AHB. See Africanized Honey Bee Ailanthus. See Tree of Heaven Ailanthus altissima. See Tree of Heaven Ailanthus glandulosa. See Tree of Heaven Ailanthus peregrine. See Tree of Heaven Air potato, 607, 660 Aizoaceae, stone plant family, 383 Akala, 536, 538, 657 Akalakala, 536, 656 Akebia quinata. See Chocolate Vine Akepa, as affected by avian malaria, 248 Alabama jumper (earthworm), 49 ALB. See Asian Longhorned Beetle Albizia julibrissin. See Silk Tree Albizzia julibrissin. See Silk Tree Albonia peregrina. See Tree of Heaven Albugo. See white leaf rust Alelaila tree. See Chinaberry Aleppo grass. See Johnsongrass Alewife, xviii (v. 1), xxiiit (v. 1), 157–60, 190, 193 state-by-state occurrences, 296, 298–310 Alfalfa dodder, 611, 660 Alfalfa dwarf (disease), Glassy-Winged Sharpshooter as vector, 137 Alien Animals (Laycock), xxxi (v. 1) Alien, definition, xiii (v. 1) Alkali bulrush. See cosmopolitan bulrush Allegheny blackberry, 524, 656 Alleleopathy Australian pine, 542 chinaberry, 553 Chinese lespedeza, 352 dyer’s woad, 364 exotic bush honeysuckles, 506 Johnsongrass, 471 kikuyugrass, 480 lantana, 521 quackgrass, 488 tree of heaven, 588 yellow starthistle, 429 Alley cat. See Feral Cat

728 n INDEX Alliaria alliaria. See Garlic Mustard Alliaria officinalis. See Garlic Mustard Alliaria petiolata. See Garlic Mustard Allorhogas species, biological control (plants) velvet tree, 592 Alosa pseudoharengus. See Alewife Alternaria solani, tropical soda apple as host, 533 Altica carduorum, biological control (plants) Canada thistle, 348 Alvars, 639 Amberique bean, 623, 660 American alligator, 663 as potentially affected by Nile monitor, 228 and West Indian marsh grass, 491 American barberry, 512, 656 American beach grass, 432, 435, 653 American bittersweet, 630–31, 632, 660 American Bullfrog, xiii (v. 1), xviii (v. 1), xxvt (v. 1), xxvi (v. 1), 205–8 as chytrid frog fungus vector, 19 ISSG 100 worst invaders, 207, 711 state-by-state occurrences, 295, 296, 298, 299, 301, 303, 304, 306, 308, 309 American bumblebee, as varroa mite host, 103 American climbing fern, 598–99, 660 American crocodile, 663 as potentially affected by Nile monitor, 228 and West Indian Marshgrass, 491 American cupscale, 489, 653 American eel, 160, 183, 191 American elm, 23 cultivars, 25 American hogpeanut, 623, 660 American Robin, 661 and exotic bush honeysuckles, 506 and multiflora rose, 525 American wisteria, 645, 660 Aminopyralid, chemical control (plants) common St. Johnswort, 361 Ampelopsis brevipedunculata. See Porcelainberry Ampelopsis glandulosa var. brevipedunculata. See Porcelainberry Ampelopsis glandulosa ‘Elegans,’ 633, 634 Ampelopsis heterophylla. See Porcelainberry Amphibians, 201–14 ISSG 100 worst invaders, 711 Amur Honeysuckle 502–8, 614 noxious designation, 666, 668, 671, 692. See also Exotic Bush Honeysuckles Amur peppervine. See Porcelainberry Amynthas agrestis. See Alabama jumper Anabasis glomerata. See Halogeton

Anacardaceae. See sumac family Anchored waterhyacinth, 339, 649 noxious designation, 665, 666, 668, 669, 670, 671, 689 Andean pampas grass. See Jubata Grass Andes grass. See Jubata Grass Andropogon vimineum. See Japanese Stilt Grass Anecic worms, 50 Angle worm, 49. See European Earthworms Anisantha tectorum. See Cheatgrass Anitimicrobial chemicals, African Clawed Frog, 204 Anjan grass. See Buffelgrass Annelid worms, 48–53, 216 Anolis distichus. See Bark anole Anolis equestris. See Knight anole Anolis garmani. See Jamaican giant anole Anoplophora glabripennis. See Asian Longhorned Beetle Antelope bitterbrush, 442, 656 Anthonomus tenebrosus, biological control (plants), tropical soda apple, 534 Antiblemma acclinalis, biological control (plants) Koster’s curse, 518 Antitoxicum rossicum. See Pale Swallow-Wort Aphalara itadori, biological control (plants) Japanese knotweed, 390 Aphids, biological control (plants), 663 Canada thistle, 347 exotic bush honeysuckle, 507 giant reed, 466 Japanese hops, 621 kikuyugrass, 481 tropical soda apple, 634 Aphtae epizooticae, Wild Pig as host, 280 Apiaceae. See carrot family Apion fuscirostre, biological control (plants) brooms, 501 Apion species, biological control (plants) velvet tree, 592 Apion ulicis, biological control (plants) gorse, 511 Apis mellifera scutellata. See Africanized Honey Bee Aplocera plagiata, biological control (plants) common St. Johnswort, 361 Aporrectodea caliginosa. See European Earthworms Applesnail. See Golden Applesnail Apthona species, biological control (plants) leafy spurge, 398 Aquarium watermoss. See Giant Salvinia Aquatic invertebrates, ISSG 100 worst invaders, 711

INDEX n 729 Aquatic plants, 321–43 American species invasive abroad, 696 ISSG 100 worst invaders, 710 noxious designation, 689 Aquatic soda apple. See wetlands nightshade Aquatic weeds, grass carp control of, 173, 174 Arachnids, 99–106 Araliacaeae. See ginseng family Archanara geminipuncta, biological control (plants) common reed, 451 Archips asiaticus, biological control (plants) chocolate vine, 596 Argentine Ant, xxii (v. 1), xxvt (v. 1), 110–13 ISSG 100 worst invaders, 711 state-by-state occurrences, 295–310 Aristolochia. See pipevine and wooly Duchman’s pipe Arizona cottontop, 436–37, 653 Arizona wheatgrass, 483, 653 Artimpaza argenteonota, biological control (plants) Asiatic colubrina, 496 Artipus floridanus, biological control (plants) Australian pine, 543 Arundo. See Giant Reed Arundo donax. See Giant Reed Arundo selloana. See Pampas Grass Arundo versicolor. See Giant Reed Asclepiadaceae. See milkweed family Asian applesnail. See Chinese Mystery Snail Asian bittersweet. See Oriental Bittersweet Asian Clam, xxiiit (v. 1), xxix (v. 1), 53–56, 77 state-by-state occurrences, 295–310 Asian euonymus scale, biological control (plants) winter creeper, 643 Asian Green Mussel, xxvt (v. 1), 56–58 state-by-state occurrences, 297, 298, 307 Asian gypsy moth, 138 Asian honey bee, as varroa mite host, 102 Asian lady beetle. See Multicolored Asian Lady Beetle Asian Longhorned Beetle, xix (v. 1), xxvt (v. 1), 113–16 ISSG 100 worst invaders, 711 state-by-state occurrences, 299, 301, 304 Asian nakedwood. See Asiatic Colubrina Asian rapa whelk. See Veined Rapa Whelk Asian snakeroot. See Asiatic Colubrina Asian Swamp Eel, 160–62 state-by-state occurrences, 297, 298, 304 Asian tapeworm, grass carp as host, 174

Asian Tiger Mosquito, xxiv (v. 1), xxvt (v. 1), 116–20 ISSG 100 worst invaders, 711 state-by-state occurrences, 295–310 Asian water monitor, 226 Asiatic bittersweet. See Oriental Bittersweet Asiatic clam. See Asian Clam Asiatic Colubrina, 493–96 impacts, 683 noxious designation, 666, 692 pathways of introduction, 675, 677 uses of, 496 Asiatic Sand Sedge, 432–35 impacts, 683 noxious designation, 666, 668, 691 pathways of introduction, 433, 675, 676 Asiatic tear-thumb. See Mile-A-Minute Asteraceae. See aster family; sunflower family Athel tamarisk, 581, 583, 658 Atlantic cordgrass. See Cordgrasses and Their Hybrids Atlantic ivy, 603–4, 660 Atlantic shipworm. See Naval Shipworm Atlantic wisteria, 645, 660 Atomacera petroa, biological control (plants) velvet tree, 592 Atrazine, chemical control (plants) cheatgrass, 443 medusahead, 485 mile-a-minute, 628 Australian Pine, 540–44 and Asiatic colubrina, 495 impacts, 681, 682, 684 noxious designation, 666, 692 pathways of introduction, 541, 675 uses of, 543 Australian pine borer, biological control (plants) Australian pine, 543 Australian river oak, 540, 541, 542, 658 Australian Spotted Jellyfish, 45–48 state-by-state occurrences, 295, 297, 298, 300, 302, 310 Austromusotima camptozonale, biological control (plants) climbing ferns, 601 Autumn olive, 568, 570 noxious designation, 570, 668, 669, 672, 692 Avian Malaria, xix (v. 1), xxvii (v. 1), 1–3, 24, 248 bird reservoir, 234 state-by-state occurrences, 298 Awapuhi kahili. See Kahili Ginger Azolla species, 327

730 n INDEX Bacterial leaf scorch (Xylalla fastidiosa), 22, 137 Bacterial leaf scorch, and Dutch Elm Disease, 22 English Ivy as host, 605 Bagous affinis, biological control (plants) hydrilla, 334 Bagpod, 528, 650 Bahamian brown anole. See Brown Anole Bald brome, 440, 653 noxious designation, 666, 691 Ball nut. See Water Chestnut Banded mystery snail, 59 Bangasternus orientalis, biological control (plants) yellow starthistle, 430 Banker horse. See Feral Horse Barberry family, 512 Barbwire Russian thistle, 411, 650 noxious designation, 665, 666, 690 Bark anole, 215 Barley, 483, 653 Basal bark application, herbicides, xx (v. 2) Basiliscus vittatus. See Brown basilisk Bat nut. See devil pod Batrachochytrium dendrobatidis. See Chytrid Frog Fungus Bat White-Nose Syndrome Fungus, xix (v. 1), 11–14 state-by-state occurrences, 297, 301–2, 304, 306, 308, 309 Bay cedar, 495, 658 Beach clustervine, 546, 660 Beach layia, 386, 650 Beach panic grass, 432, 435, 653 Beach she-oak. See Australian pine Beachstar, 546, 654 Bead tree. See Chinaberry Bean aphid, Canada thistle host, 347 Bean stalk borer, Canada thistle host, 347 Bearberry honeysuckle, 505, 656 Beardless wheatgrass, 487, 654 Bedbug. See Common Bed Bug Bee colonies destruction, by varroa mite, 104–5 Beefwood. See Australian pine Beetles, biological control (plants) Asiatic colubrina, 496 Brazilian peppertree, 547–48 Canada thistle, 348 climbing ferns, 601 common St. Johnswort, 361 garlic mustard, 372 hydrilla, 334 Japanese hops, 621 Japanese knotwood, 390 Koster’s curse, 518

kudzu, 625 leafy spurge, 398–99 melaleuca, 561 purple loosestrife, 417 rattlebox, 529 tamarisk, 585 toadflax, 426 tropical soda apple, 534 velvet tree, 592 water chestnut, 338 Begomovirus. See tobacco leaf curl Bell’s honeysuckle, 502–8 noxious designation, 666, 668, 669, 691, 692. See also Exotic Bush Honeysuckles Belut eel. See Asian Swamp Eel Berberidaceae. See barberry family Berberis japonica. See Japanese Barberry Berberis sinensis. See Japanese Barberry Berberis thunbergia var. atropurpurea. See Japanese Barberry Berberis thunbergii. See Japanese Barberry Berberis x ottawensis, 512 Bergmann’s Rule, xxxi (v. 1), 312, 714 Bermuda grass, 479, 654 Big Cypress National Preserve West Indian marsh grass, 490 melaleuca, 559 Big Cypress National Preserve, spotted tilapia, 197 Burmese python, 218 melaleuca, 559 Big eye herring. See Alewife Bighead. See hyperparathyroidism Bighead Carp, xxvt (v. 1), 163–66, 195 state-by-state occurrences, 295–300, 302–3, 306–9 Bignonia tomentosa. See Princess Tree Big sage. See Lantana Big taper. See Common Mullein Biogeography, xiii (v. 1), xxxii (v. 1) Biological control (plants). See species entries Birds, 228–59 Bishop’s goutweed. See Goutweed Bishop’s weed. See Goutweed Bitter panicum, 432 Black acacia. See Rattlebox Black carp, 172 Black dog-strangle vine. See Black Swallow-Wort Blackfin cisco, 193 Black-hooded Parakeet. See Nanday Conure Black imported fire ant, 152 Black-legged tick as Lyme disease vector, 4, 5, 6 Black mangrove cichlid. See Spotted Tilapia

INDEX n 731 Black Rat, xviii (v. 1), xxvit (v. 1), 259–62, 287 ISSG 100 worst invaders, 261, 712 state-by-state occurrences, 295–310 Blacksage. See Lantana Black snail. See Chinese Mystery Snail Black spinytail iguana, 222–23 Black stem grain rust, 513 Black Swallow-Wort, 636–40 impacts, 678, 680, 684 noxious designation, 666, 668, 669, 671, 693. See also Swallow-Worts Bladderpod. See bagpod Blady grass. See Cogongrass Blue toadflax. See Canada toadflax BMSB. See Brown Marmorated Stink Bug Bohemian knotweed. See giant knotweed Boiga irregularis. See Brown tree snake Bootanelleus orientalis, biological control (plants) Australian pine, 543 Boreioglycaspis melaleucae, biological control (plants) melaleuca, 561 Borrelia burgdorferi. See Lyme Disease bacterium Boston ivy, 603, 633, 660 Bothriocephalus opsarichthydis, 174 Botrylloides diagensis, 40 Botrylloides perspicuum, 40 Botrylloides violaceus. See Chain Tunicate Botryllus schlosseri, 40 Botrytis cinerea, biological control (plants) fire tree, 557 Botrytis cinerea, fire tree control, 557 Bowfin, 182, 183 Branch herring. See Alewife Brachypterolus pulicarius, biological control (plants) toadflax, 426 Branched tearthumb, 600, 650 Brassicaceae. See mustard family Brazilian elodea. See Brazilian waterweed Brazilian oak, 540, 541–42, 543, 658 Brazilian Peppertree, 495, 544–48, 560 impacts, 682, 684, 685 ISSG 100 worst invaders, 710 noxious designation, 666, 671, 692 pathways of introduction, 673 uses of, 547 Brazilian satintail, 445, 654 noxious designation, 665, 666, 668, 669, 670, 671, 691 Brazilian waterhyacinth, 440, 649 Brazilian waterweed, 332, 334, 649 Breea arvensis. See Canada Thistle Breea incana. See Canada Thistle

Bridal broom, 498, 656 Bristletips, 515, 589–90, 656 British Petroleum oil spill (2010), 329 Broadleaf toadflax, 424, 650 Broadleaved pepperweed. See Perennial Pepperweed Broad-leaved toadflax. See Dalmatian Toadflax Broghammerus reticulates, 220 Bromacil, chemical control (plants) Brazilian peppertree, 547 Bromeliads, 495, 660, 661 Bromus tectorum. See Cheatgrass Broncograss. See Cheatgrass Broomleaf toadflax, 424, 650 Brooms, 496–502, 509 impacts, 679, 681, 683 noxious designation, 666, 667, 670, 671, 692 pathways of introduction, 673, 675, 676 uses of, 502 Brotogeris chiriri. See Yellow-chevroned Parakeet Brotogeris versicolurus. See White-winged Parakeet Broussonetia papyrifera. See Paper Mulberry Brown Anole, xviii (v. 1), 214–17 state-by-state occurrences, 297, 298 Brown basilisk, 223 Brown Marmorated Stink Bug, xix (v. 1), xxvt (v. 1), xxx (v. 1), 120–23 state-by-state occurrences, 296, 297, 304–6, 307, 309 Brown rat. See Norway Rat Brown tree snake, xxiv (v. 1), xxvii (v. 1), 210 Brown Trout, xxivt (v. 1), 159, 166–68, 185 ISSG 100 worst invaders, 168, 711 state-by-state occurrences, 295–310 Bruchus atronotatus, biological control (plants) Brazilian peppertree, 548 Bryozoans, 36–38 Bubulcus ibis. See Cattle Egret Buckthorn family, 493 Buckwheat family, 387, 626 Budgerigars, 250 Buffalobur, 533, 650 noxious designation, 667, 670, 671, 690 Buff-backed heron. See Cattle Egret Buffelgrass, 435–39 impacts, 679, 683 noxious designation, 665, 691 pathways of introduction, 675 Bulb panicgrass, 470, 654 Bulbous buttercup. See Fig Buttercup

732 n INDEX Bull thistle, 345–46, 348–49, 401, 403, 650 noxious designation, 666, 667, 668, 669, 670, 671, 690 Burbot, 182, 183 Bur cucumber, 619, 660 Bureau of Land Management (BLM) feral burros, 262, 264–65 feral horses, 273, 274–75 Burgdorfer, Dr. Willy, 5 Burmese Python, xviii (v. 1), xxivt (v. 1), 217–21 state-by-state occurrences, 297, 310 Burning, physical control (plants) Australian pine, 543 Canada thistle, 348 cheatgrass, 442–43 Chinese lespedeza, 352 common reed, 450–51 English ivy, 605 exotic bush honeysuckles, 506 garlic mustard, 371 giant reed, 465 gorse, 511 Japanese barberry, 514 Japanese dodder, 613 Japanese stilt grass, 469 medusahead, 484 quackgrass, 488 tamarisk, 584 tree of heaven, 588 yellow starthistle, 430 Burning bush, 380, 641, 643, 650, 656 noxious designation, 666, 660, 671, 690 pathways of introduction, 673 Bursting heart, 641, 643, 656 Bush currant. See Velvet Tree Bush honeysuckles. See Exotic Bush Honeysuckles Bush morning glory. See western morning glory Bush muhly, 437, 654 Bushy white solanum. See turkey berry Butter and eggs. See Yellow Toadflax Buttercup family, 366 Butterflies and Canada thistle, 348 and garlic mustard, 371 and Japanese stiltgrass, 468, and swallow-worts, 639 Butterflies, biological control (plants) fire tree, 557 garlic mustard, 371 Bythotrephes cederstroemi, 96 Bythotrephes longimanus. See Spiny Water Flea

California broom, 498 California Clapper Rail, 661 and cordgrass, 457 California cordgrass, 453, 454–55, 456, 457, 654. See also Cordgrasses and Their Hybrids California peppertree. See Peruvian peppertree California satintail, 445, 654 noxious designation, 666, 691 Californian thistle. See Canada Thistle Calophasia lunula, biological control (plants) toadflax, 426 Caloptilla sp. nr. schinella, biological control (plants) fire tree, 557 Camasey. See Koster’s Curse Canada germander, 414, 650 Canada Thistle, 344–49, 401 impacts, 678, 679, 682, 685 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 690 pathways of introduction, 677 Canada thistle stem weevil, xxiv (v. 1), 348 Canada toadflax, 424, 650 Canadian honeysuckles, 505, 656 Canadian waterweed, 332, 649 Canary Island St. Johnswort, 359, 656 Canby’s mountain-lover, 643, 656 Candleberry myrtle. See Fire Tree Cane. See Common Reed Cane ti, 515, 589–90, 656 Cane tibouchina. See cane ti Cannabidaceae. See hemp family Caper spurge, 396, 650 Capra hircus. See Feral Goat Caprifoliaceae. See Honeysuckle family Carcinus maenas. See Green Crab Carderia draba. See Hoary Cress Cardaria latifolia. See Perennial Pepperweed Carduus acanthoides. See plumeless thistle Carduus arvensis. See Canada Thistle Carduus nutans. See Musk Thistle Carduus pycnocephalus. See Italian thistle Carduus species, 344, 345, 399–404, 651, 652 noxious designation, 605, 607 pathways of introduction, 677. See also Musk Thistle Carduus tenuflorus. See slender-flowered thistle Carex kobomugi. See Asiatic Sand Sedge Caribbean fruit fly, 663 strawberry guava as host, 578, 579 Carolina horsenettle, 533, 650 noxious designation, 665, 666, 667, 669, 690

INDEX n 733 Carolina Parakeet, xxix (v. 1), 251 Carpobrotus edulis. See Ice Plant Carpodacus mexicanus. See House Finch Carposina bullata, biological control (plants) Koster’s curse, 518 Carrizo. See Giant Reed Carrot family, 372, 376 Carrot weed. See Carrotwood Carrotwood, 548–51 impacts, 684 noxious designation, 666, 692 pathways of introduction, 673, 676 Cartwheel-flower. See Giant Hogweed Cassida rubiginosa, biological control (plants) Canada thistle, 348 Casuarina. See Australian Pine Casuarinaceae. See casuarina family Casuarina equisetifolia. See Australian Pine Casuarina litorea. See Australian Pine Casuarina littorea. See Australian Pine Casuarina family, 540 Catalpa, 566, 659 Caterpillars, biological control (plants) giant reed, 466 Japanese stiltgrass, 468 lantana, 521 Cat facing, fruit deformation, 122 Cattle forage for, 437, 441, 445, 470, 479, 480, 489 Johnsongrass, 472 leafy spurge, 398 plants toxic to, common St. Johnswort, 360 toadflax, 425, 521 Cattle Egret, xiv (v. 1), xxi (v. 1), 228–32 state-by-state occurrences, 295–310 Cattley guava, 576 Cayuga Lake, and Eurasian watermilfoil, 325 Celandine, 367, 650 Celandine poppy, 367, 650 Celastraceae. See staff-tree family; staff-vine family Celastrus articulatus. See Oriental Bittersweet Celastrus orbiculatus. See Oriental Bittersweet Celastrus sepiarius. See Asiatic Colubrina Cenchrus ciliaris. See Buffelgrass Cenchrus glaucus. See Buffelgrass Cenchrus setaceus. See Crimson Fountain Grass Centaurea biebersteinii. See Spotted Knapweed Centaurea maculosa. See Spotted Knapweed Centaurea solstitialis. See Yellow Starthistle Centaurea stoebe. See Spotted Knapweed Ceonothus asiaticus. See Asiatic Colubrina

Ceonothus capsularis. See Asiatic Colubrina Cercopagis pengoi. See Fishhook water flea Cercospora rodmanii, biological control (plants) waterhyacinth, 343 Ceutrhynchus litura. See Canada thistle stem weevil Ceutrhynchus species, biological control (plants) garlic mustard, 372 Ceutrhynchus trimaculatus, biological control (plants) musk thistle, 403 Chaetococcus phragmitis. See legless red mealybug Chaetorellia species, biological control (plants) yellow starthistle, 431 Chain sea squirt. See Chain Tunicate Chain Tunicate, xxiv (v. 1), xxvt (v. 1), 39–41, 42 state-by-state occurrences, 295–97, 300, 301, 303, 304, 306, 308, 309 Chamaespecia species. See clearwing moths Channa argus. See Northern Snakehead Channeled apple snail. See Golden Apple Snail Chaparral false bindweed. See western morning glory Character displacement, feeding adaptation, 243 Charru mussel, 56 Cheatgrass, 439–43 impacts, 678, 679, 685 and medusahead, 484 noxious designation, 666, 691 pathways of introduction, 676, 677 uses of, 443 Cheeseberry. See Yellow Himalayan Raspberry Cheilosia corydon, biological control (plants) musk thistle, 403 Chemical control (plants). See species entries Chenopodiaceae. See goosefoot family Cherokee rose, 523, 656 pathways of introduction, 673 Cherry guava. See Strawbery Guava Chestnut bark disease fungus. See Chestnut Blight Fungus Chestnut Blight Fungus, xxvit (v. 1), xxviii (v. 1), 14–17, 34 state-by-state occurrences, 295–310 Chewing disease. See nigropalallidal encephalomalacia Chinche. See Common Bed Bug Chilean iceplant. See sea fig Chilo phragmitella, biological control (plants) common reed, 451 Chinaberry, 551–54 impacts, 681, 684 noxious designation, 692

734 n INDEX pathways of introduction, 673 uses of, 554 China tree. See Chinaberry Chinese bush clover. See Chinese Lespedeza Chinese-glysine. See Wisteria Chinese honeysuckle, 614, 660. See also Japanese Honeysuckle Chinese Lespedeza, 349–53 impacts, 680, 682 noxious designation, 666, 667, 690 pathways of introduction, 676 Chinese Mitten Crab, xxiiit (v. 1), 86–89 ISSG 100 worst invaders, 711 state-by-state occurrences, 296 Chinese Mystery Snail, xxiiit (v. 1), 58–61 state-by-state occurrences, 295–97, 299–310 Chinese packing grass. See Japanese Stilt Grass Chinese rose beetle, biological control (plants) velvet tree, 592 Chinese sumac. See Tree of Heaven Chinese tamarisk. See Tamarisk Chinese turtledove, and lantana, 520, 661 Chinese wisteria. See Wisteria. See also Rattlebox Chinese yam, 603, 607, 660 Chlopyralid, chemical control (plants) wisteria, 647 Chlorflurenol, chemical control (plants) ice plant and crystalline ice plant, 386 Chlorsulfuron, chemical control (plants) Canada thistle, 348 dyer’s woad, 365 pepperweed and hoary cress, 409 Chocolate Vine, 594–97 impacts, 684 pathways of introduction, 673 uses of, 597 Christmasberry. See Brazilian Peppertree Chukar Partridge, 661 and cheatgrass, 443 and Medusahead, 484 Chrysobothris tranquebarica. See Australian pine borer Chrysolina species, biological control (plants) common St. Johnswort, 361 Chytonix segregate, biological control (plants) Japanese hops, 621 Chytrid fungus. See Chytrid Frog Fungus Chytrid Frog Fungus, xv (v. 1), 13, 18–21 African clawed frog as host, 204 American bullfrog as host, 207 state-by-state occurrences, 295–10 Chytridomycosis, 13, 204, 207 Cicadallid cotton pest, and Japanese honeysuckle, 617

Cichla ocellaris. See Peacock cichlid Cimex lectularius. See Common Bed Bug Cimex hemipterus, 124 Cinnamon vine, 603, 660 Cipangopaludina chinensis malleata. See Chinese Mystery Snail Cipangopaludina japonica. See Japanese mystery snail Cirsium arvense. See Canada Thistle Cirsium setosum. See Canada Thistle Cirsium species, 401 Cirsium vulgare. See bull thistle Cissus brevipedunculata. See Porcelainberry Clarias batrachus. See Walking Catfish Clastoptera undula, biological control (plants) Australian pine, 543 Clearwing moths, biological control (plants) leafy spurge, 398 Cleonis pigra, Canada thistle control, 349 Clethodim, chemical control (plants) quackgrass, 488 Cletus schmidti, biological control (plants) mile-a-minute, 629 Clidemia. See Koster’s Curse Clidemia crenata. See Koster’s Curse Clidemia elegans. See Koster’s Curse Clidemia hirta. See Koster’s Curse Climbing euonymus. See Winter Creeper Climbing fern family, 597 Climbing ferns, 597–602 impacts, 680, 684 noxious designation, 665, 667, 693 pathways of introduction, 673 Climbing milkweed. See Black Swallow-Wort Climbing nightshade, 532, 637, 660 Climbing prairie rose, 524, 656 Climbing spindleberry. See Oriental Bittersweet Clitocybe tabescens, biological control (plants) Australian pine, 543 Clopyralid chemical control (plants) Canada thistle, 348 Chinese lespedeza, 352 common mullein, 352 spotted knapweed, 421 yellow strarthistle, 430 Clusiaceae. See mangosteen family Cnidarians, 45–48 Coachella Valley Preserve tamarisk eradication, 584 Coastal sand spurge, 434, 650 Coast she-oak. See Australian Pine Cobicula fluminea. See Asian Clam Coccinella septempunctata. See Seven-spotted lady beetle

INDEX n 735 Cochlearia draba. See Hoary Cress Cockroach berry, 532–33, 656 Cocostroma myconae, biological control (plants) velvet tree, 592 Codium fragile tomentosoides. See Dead man’s fingers Coffee colubrina, 493, 656 Cogon grass. See Cogongrass Cogongrass, 443–47 impacts, 679, 683 pathways of introduction, 675 ISSG 100 worst invaders, 710 noxious designation, 665, 666, 667, 668, 669, 670, 671, 691 Colchis ivy, 604, 660 Coleophora klimeschiella, biological control (plants) prickly Russian thistle, 413 Coleophora parthenica, biological control (plants) halogeton, 383 prickly Russian thistle, 413 Colletotrichum gloesporioides, biological control (plants) Koster’s curse, 518 kudzu, 625 Colletotrichum gloesporioides f. sp. miconiae, biological control (plants) velvet tree, 592 Colonial ascidian. See Colonial Tunicate Colonial sea squirt. See Colonial Tunicate Colonial Tunicate, xxiv (v. 1), xxvt (v. 1), 42–45 state-by-state occurrences, 296, 300, 303, 304, 306, 309 Colorado potato beetle, and tropical soda apple as host, 533–34, 663 Colubrina asiatica. See Asiatic Colubrina Columba livia. See Rock Pigeon Columnar cactus, 495, 658 Common barberry, 512–13, 656 noxious designation, 666, 668, 669, 692 Common Bed Bug, xix (v. 1), xxvt (v. 1), xxvt (v. 1), 123–27 state-by-state occurrences, 295–310 Common colubrina. See Asiatic Colubrina Common coqui. See Coqui Common cordgrass. See Cordgrasses and Their Hybrids; noxious designation, 670, 671, 691; pathways of introduction, 675 Common dodder, 611, 660 Common elderberry, 374, 551, 656 Common goatweed. See Common St. Johnswort Common gorse. See Gorse Common guava, 577, 578, 579, 659

Common hops, 619, 621, 660 Common hornwort. See coontail Common ice plant. See Crystalline Ice Plant Common iguana. See Green Iguana Common Mullein, xiii (v. 2), 353–57 impacts, 682, 685 pathways of introduction, 674, 675 noxious designation, 666, 667, 690 uses of, 357 Common Myna, xxiiit (v. 1), 1, 232–34 ISSG 100 worst invaders, 234, 712 lantana, 520 state-by-state occurrences, 297 strawberry guava, 578 and velvet tree, 591 Common parsnip, 373, 650 Common Periwinkle, 61–63 state-by-state occurrences, 297, 300, 301, 304, 306 Common pigeon. See Rock Pigeon Common platanna. See African Clawed Frog Common Reed, 447–51 and Giant Reed, 463 impacts, 683 noxious designation, 665, 666, 668, 670, 671, 691 pathways of introduction, 677 uses of, 451 Common saltwort. See Prickly Russian Thistle Common salvinia, 327, 649, 328, 329 Common St. Johnswort, 358–62 impacts, 678, 679, 680, 682 in medicine, 361 noxious designation, 666, 668, 669, 670, 671, 672 pathways of introduction, 675 Common toadflax. See Yellow Toadflax Contact herbicides, xx (v. 2) Convolvulaceae. See morning glory family Convolvulus ambigens. See Field Bindweed Convolvulus arvensis. See Field Bindweed Convolvulus incanus. See Field Bindweed Coontail, 322, 649 Copal. See Brazilian Peppertree Copal-tree. See Tree of Heaven Copper chelate, chemical control (plants) waterhyacinth, 342 Copper sulfate biological control (plants) waterhyacinth, 342 Coptotermes formosanus. See Formosan Subterranean Termite Coqui, xxvi (v. 1), xxx (v. 1), 208–11 ISSG 100 worst invaders, 210, 711 state-by-state occurrences, 297, 298

736 n INDEX Coquı´ comu´n. See Coqui Coral honeysuckle, 615, 641, 660 Coralberry, 505, 656 Cordgrass. See Cordgrasses and Their Hybrids Cordgrasses and Their Hybrids, 63, 274, 293, 452–56 American species invasive abroad, 696 impacts, 682, 683 noxious designation, 670, 671, 691, 692 pathways of introduction, 675, 676, 677 Corn bind. See Field Bindweed Corn thistle. See Canada Thistle Cortaderia. See Jubata Grass Cortaderia argentea. See Pampas Grass Cortaderia atacamensis. See Jubata Grass Cortaderia dioica. See Pampas Grass Cortaderia jubata. See Jubata Grass Cortaderia selloana. See Pampas Grass Cosmopolitan bulrush, 455, 654 Cotton States Exposition (1884), Waterhyacinth introduction, 340 Couch grass. See Quackgrass Council of Europe, and Water Chestnut, 338 Cow parsnip. See common parsnip Coypu. See Nutria Crasimorpha infuscate, biological control (plants) Brazilian peppertree, 548 Crassostrea gigas. See Japanese oyster Crater Lake National Park, and white pine blister rust, 34 Crawdad. See Rusty Crayfish Crawfish. See Rusty Crayfish Cream lily. See yellow ginger Creeper. See Porcelainberry Creeping Charlie. See field bindweed; ground ivy Creeping Jenny. See field bindweed Creeping thistle. See Canada Thistle Creeping wild rye. See Quackgrass Crested wheatgrass, 485, 487, 654 Cricotopus myriophylli. See milfoil midge Crimson beauty. See Japanese Knotweed Crimson bottlebrush, 558, 657 Crimson Fountain Grass, 458–62 noxious designation, 667, 691 pathways of introduction, 673 Crinkleroot, 371, 650 Cristulariella pyramidalis. See zonate leafspot Cronartium ribicola. See White Pine Blister Rust Crustaceans, 86–99 American species invasive abroad, 696 Cryphonectria parasitica. See Chestnut Blight Fungus Cryophytum crystallinum. See Crystalline Ice Plant

Crystalline Ice Plant, 383–87 impacts, 682 noxious designation, 690 pathways of introduction, 677 Ctenopharyngodon idella. See Grass Carp Ctenosaurus similis. See Black spinytail iguana Cuban brown anole. See Brown Anole Cuban nakedwood, 493, 657 Cuban Treefrog, xx (v. 1), xxviii (v. 1), xxxii (v. 1), 211–14, 227 state-by-state occurrences, 297, 310 Cucullia verbasci. See mullein moth Cucumber, 619 Culex quinquefasciatus. See Southern house mosquito Cultivation, physical control (plants). See tilling Cupania anacardioides. See Carrotwood Cupania anacardioides var. parvifolia. See Carrotwood Cupaniopsis anacardioides. See Carrotwood Currants, White Pine Blister Rust alternate host, 30, 32, 34 Curvulara lunata, biological control (plants) West Indian marsh grass, 492 Cuscutaceae family. See morning glory family Cuscuta japonica. See Japanese Dodder Cutleaf toothwart, 371, 650 Cutting or mowing, physical control (plants) brooms, 501 cheatgrass, 442 chocolate vine, 596 dyer’s woad, 365 English ivy, 605 giant reed, 465 gorse, 511 Japanese barberry, 514 Japanese dodder, 613 Japanese hops, 621 Japanese knotweed, 390 Japanese stilt grass, 468–69 Johnsongrass, 472 kudzu, 625 mile-a-minute, 628 multiflora rose, 525 oriental bittersweet, 632 rattlebox, 529 swallow-worts, 639 toadflax, 426 winter creeper, 643 wisteria, 647 yellow starthistle, 430 Cyanophyllum magnificum. See Velvet Tree Cygnus olor. See Mute Swan Cynanchum medium. See Pale Swallow-Wort

INDEX n 737 Cynanchum rossicum. See Pale Swallow-Wort Cyperaceae. See sedge family Cyphocleonus achates, biological control (plants) spotted knapweed, 421 Cypress spurge, 396, 650 Cytisus monspessulana. See French Broom Cytisus scoparius. See Scotch Broom Cytisus striatus. See Portuguese Broom Crytobagous salviniae, biological control (plants) giant salvinia, 330 Dalmatian toadflax, 421–26 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 690 pathways of introduction, 674 Dark-green white-eye, 246 Daubentonia punicea. See Rattlebox Davis Pond Freshwater Diversion Project giant salvinia, 329 Dead man’s fingers (green algae), 37 Deer, and leafy spurge, 397 Deer mice, 281, 662 Deer tick, as Lyme disease vector, 4, 5, 6 Deformed wing virus (DWV), bee virus, 105 Dendrobaena octaedra. See European Earthworms Dendryphiella broussonetiae, biological control (plants) paper mulberry, 564 Dengue fever, xix (v. 1), xx (v. 1), 7, 119 Dense-flowered cordgrass, noxious designation, 671, 691 pathways of introduction, 676, 677. See also Cordgrasses and Their Hybrids Depressed shrubverbena. See pineland lantana Devil firefish, 175, 176, 176 Devil pod, 336, 649 Devil’s apple. See cockroach berry Devil’s fig. See turkey berry Devils-grass. See Quackgrass Devil’s guts. See Field Bindweed Devil’s hair. See Japanese Dodder Devil’s tail tear-thumb. See Mile-A-Minute Diatraea succharalis, biological control (plants) giant reed, 466 Dicamba, chemical control (plants) Australian pine, 543 gorse, 511 Japanese honeysuckle, 617 multiflora rose, 525 musk thistle, 403 prickly Russian thistle, 413 spotted knapweed, 421 strawberry guava, 578

tamarisk, 585 tropical soda apple, 534 Didemnid. See Colonial Tunicate Didemnum vexillum. See Colonial Tunicate Diffuse knapweed, 419, 650 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 690 Digging out, hand pulling, or bulldozing, physical control (plants) Asiatic colubrina, 495 buffelgrass, 438 cordgrasses, 457 dyer’s woad, 364 giant hogweed, 375 ice plant, 386 Japanese barberry, 514 Japanese hops, 621 Japanese stilt grass, 468 Kahili ginger, 394 mile-a-minute, 628 porcelainberry, 635 tamarisk, 584 velvet tree, 592 Diorhabda elongate. See saltcedar leaf beetle Dioscorea species, 607, 660 Diplodia natalensis, biological control (plants) Australian pine, 543 Diquat, chemical control (plants) giant salvinia, 329 Dittander. See Perennial Pepperweed Dodder, 386. See also Japanese Dodder Dog grass. See Quackgrass Dog rose, 523–24, 657 Dog-strangling vine. See Pale Swallow-Wort Dolichos hirsutus. See Kudzu Dolichos lobatus. See Kudzu Dollar leaf plant. See prostrate tickrefoil Domesticated livestock, xviii (v. 1), xxiv (v. 1) Dorosoma cepedianum. See Gizzard Shad Downy brome. See Cheatgrass Downy chess. See Cheatgrass Drake, J. A., xxxi (v. 1) Dreissena polymorpha. See Zebra Mussel Dreissena rostriformis bugensis. See Quagga mussel Drooping brome. See Cheatgrass Drummond rattlebox, 528–29, 657 Dutch Elm Disease Fungi, xix (v. 1), xxvi (v. 1), 21–25, 115, 130 state-by-state occurrences, 295–310 Dutchman’s pipe, 603, 660 Dwarf euonymus. See Winter Creeper Dwarf gorse, 509, 657 Dwarf honeysuckle. See European fly honeysuckle

738 n INDEX Dwarf St. Johnswort, 359, 650 Dyer’s Woad, 362–66 impacts, 678, 680, 682 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 690 pathways of introduction, 675, 677 uses of, 365 EAB. See Emerald Ash Borer Early chess. See Cheatgrass Early saxifrage, 370, 650 Eastern mosquito fish. See Mosquitofish Ebola, xix (v. 1) Ecological impacts, xxvi–xxvii (v. 1) in natural and semi-natural ecosystems, xxvii–xxix (v. 1). See also species entries Ecology of Biological Invasions of North American and Hawaii (Mooney and Drake), xxxi (v. 1) “Ecology of Biological Invasions” (ICSU), xxxi (v. 1) Ecology of Invasions by Animals and Plants, The (Elton), xxx (v. 1) Economic impacts, xxix–xxxi (v. 1). See also species entries Edible Periwinkle. See Common Periwinkle Eleutherodactylus coqui. See Coqui Eleutherodactylus planirostris. See Greenhouse frog Eggleaf spurge, 396, 650 Eggs and bacon. See Yellow Toadflax Eichhornia crassipes. See Waterhyacinth Eichhornia speciosa. See Waterhyacinth Elaeagnaceae. See oleaster family Elaeagnus augustifolia. See Russian Olive Elaeagnus hortensis. See Russian Olive Elaeagnus iliensis. See Russian Olive Elaeagnus umbellate. See autumn olive Elaeodendron fortunei. See Winter Creeper Eleocharus dulcis, 335 Elephant grass, 459, 460, 654 noxious designation, 691 Elm yellows, 22 Elongate paulownia, 566, 568, 659 Elton, Charles S., xx (v. 1) Elymus caput-medusae. See Medusahead Elymus repens. See Quackgrass Elytrigia repens. See Quackgrass Elytrigia vaillantiana. See Quackgrass Emerald Ash Borer, xxvit (v. 1), xxix (v. 1), 127–31 state-by-state occurrences, 299–302, 305, 309, 310

Emerging infectious diseases, xix (v. 1) Empoasca biguttula, Japanese honeysuckle as host, 617 Empress tree. See Princess Tree Enchanted Lake (O’ahu), giant salvinia, 329 Endothall, chemical control (plants) hydrilla, 334 “English House Sparrow Has Arrived in Death Valley, The An Experiment in Nature” (Grinnell), xxxi (v. 1) English ivy, 602–6 impacts, 684, 685 noxious designation, 670, 671, 693 pathways of introduction, 673, 681 and winter creeper, 641 English Sparrow. See House Sparrow Epigeic worms, 51 Epirrhoe sepergressa, biological control (plants) Japanese hops, 621 Episimus utilis, biological control (plants) Brazilian peppertree, 548 Equus asinus. See Feral Burro Equus caballus. See Feral Horse Eriocheir japonicus. See Japanese mitten crab Eriocheir sinensis. See Chinese Mitten Crab Erophora cardui, biological control (plants) Canada thistle control, 348 Erysiphe cichoracearum, biological control (plants) common mullein, 357 Erysium alliaria. See Garlic Mustard Eteobalea species, biological control (plants) toadflax, 426 Eucerocoris suspectus, biological control (plants) melaleuca, 561 Eucalyptus family, 557 Eucerocoris suspectus. See leaf-blotching bug Euhrychiopsis lecontei, biological control (plants) Eurasian watermilfoil, 324–25 Eulalia. See Japanese Stilt Grass Eulalia viminea. See Japanese Stilt Grass Eunectes murinus, 220 Eunectes notaeus, 220 Euonymus. See Winter Creeper Euonymus fortunei. See Winter Creeper Euonymus species. See Winter Creeper Euphorbiaceae. See spurge family Euphorbia esula. See Leafy Spurge Euphorbia virgata. See Leafy Spurge Eurasian Collared-Dove, 234–37 state-by-state occurrences, 295, 296, 297–300, 302–8

INDEX n 739 Eurasian Watermilfoil, 173, 321–26, 334, 336 grass carp, 173, 325 impacts, 680, 681, 682, 685 noxious designation, 665, 666, 667, 668, 669, 670, 671, 689 pathways of introduction, 677 Eurasian wild boar. See Feral Pig European bindweed. See Field Bindweed European Earthworms, 48–53 state-by-state occurrences, 296–310 European fly honeysuckle, 504–5, 614, 657 European green crab. See Green Crab European gypsy moth. See Gypsy Moth European honey bee, xix (vol 1), 99, 102, 103, 105, 106, 107, 108, 109 European rose chalicid, biological control (plants) multiflora rose control, 526 European shore crab. See Green Crab European Starling, xviii (v. 1), xxiiit (v. 1), xxx (v. 1), 237–40 ISSG 100 worst invaders, 240, 712 and oriental bittersweet, 631 state-by-state occurrences, 295–310 European swallow-wort. See Pale Swallow-Wort European Tree Sparrow, 244 European wand loosestrife, 414, 657 European water chestnut. See Water Chestnut European wild boar. See Feral Pig Eustenopus villosus, biological control (plants) yellow starthistle, 431 Evecliptopera decurrens, biological control (plants) chocolate vine, 596 Everglades threats from invasive species, xvi (v. 1), 162, 197, 199, 218, 219, 220, 223, 490 Australian pine, 541, 542–43 Brazilian peppertree, 545, 546 climbing ferns, 599, 600 melaleuca, 558, 559, 560 West Indian marsh grass, 490 Everglade Snail Kite, 661 and waterhyacinth, 342, and West Indian marshgrass, 491 Everglades National Park, threats from invasive species, xvi (v. 1), xviii (v. 1) Asian swamp eel, 162 Burmese python, 218, 219, 220–21 green iguana 223 spotted tilapia, 197 walking catfish, 199 Executive Order 13112 (February 3, 1999), xiii (v. 1), xv (v. 1), 703

Exotic Bush Honeysuckles, 121, 502–8 impacts, 681, 683 and Japanese honeysuckle, 614 noxious designation, 666, 668, 669, 671, 692 pathways of introduction, 673, 674, 675, 676 Fabaceae. See pea family Fallopia japonica. See Japanese Knotweed False peacock fly, biological control (plants) yellow starthistle, 431 False poinciana. See Rattlebox Faya bush. See Fire Tree Fayatree. See Fire Tree Feathertop, 460, 654 Feathery pennisetum. See missiongrass Federal Noxious Weed Act, xv (v. 1), 701 Felis silvestris catus. See Feral Cat Feral Burro, 262–65 state-by-state occurrences, 295, 296, 303, 306–8 Feral Cat, xxivt (v. 1), xxxv (v. 1), 265–68 ISSG 100 worst invaders, 268, 712 state-by-state occurrences, 295–310 Feral Goat, xviii (v. 1), xxiiit (v. 1), 268–71 ISSG 100 worst invaders, 712 state-by-state occurrences, 296, 298 Feral hog/swine, 275 and tropical soda apple, 533 Feral Horse, xxiiit (v. 1), 271–75 state-by-state occurrences, 295, 296, 298, 303–10 Feral Pig, xviii (v. 1), xxiiit (v. 1), 275–81 fire tree, 556 ISSG 100 worst invaders, 280, 712 state-by-state occurrences, 295, 296, 297–300, 302, 303, 305, 306, 307, 308, 309, 310 and strawberry guava, 578 Feral pigeon. See Rock Pigeon Fergusonina species, biological control (plants) melaleuca, 561 Ficaria ranunculoides. See Fig Buttercup Ficaria verna. See Fig Buttercup Field Bindweed, 606–10 impacts, 678, 679, 684, 685 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 693 pathways of introduction, 673, 675 Field morning glory. See Field Bindweed Field thistle. See Canada thistle Fig Buttercup, 366–68 impacts, 682

740 n INDEX noxious designation, 668, 690 pathways of introduction, 673 Figwort family, 421, 422, 565, 719 Fire, physical control (plants). See burning Firebush. See Fire Tree Fire hazard brooms, 500 climbing ferns, 600 cogongrass, 446 common reed, 450 crimson fountain grass, 462 giant reed, 465 gorse, 511 Johnsongrass, 472 jubata grass, 477 kikuyugrass, 480 lantana, 521 medusahead, 484 melaleuca, 560 prickly Russian thistle, 412 Russian olive, 572 Firetree. See Fire Tree Fire Tree, 248, 554–57 ISSG 100 worst invaders, 710 noxious designation, 666, 667, 693 pathways of introduction, 673, 676, Fireweed, 414, 651 Fish, 157–201 American species invasive abroad, 697 ISSG 100 worst invaders, 711 Fishhook water flea, 97, 711 Five-leaf akebia. See Chocolate Vine Five-stamen tamarisk, 579, 580, 581. See also Tamarisk Flannel leaf. See Common Mullein Flannel mullein. See Common Mullein Flaxweed. See Yellow Toadflax Flies, biological control (plants) Brazilian peppertree, 548 Canada thistle, 348 climbing ferns, 601 common reed, 451 hydrilla, 334 lantana, 521 melaleuca, 561 mile-a-minute, 629 musk thistle, 403 Russian knapweed, 421 strawberry guava, 578 velvet tree, 592 waterhyacinth, 342 yellow Himalayan raspberry, 539 yellow starthistle, 431

Floating fern. See Giant Salvinia Floating fern family, 326 Floating waterhyacinth. See Waterhyacinth Florida apple snail, 68 Florida elodea. See Hydrilla Florida holly. See Brazilian Peppertree Florida Keys National Marine Sanctuary, 178 Florida thatch palm, 659 and Asiatic colubrina, 495 Flowered sage. See Lantana Fluazifop, chemical control (plants) cogongrass, 447 jubata grass, 477 pampas grass, 477 quackgrass, 488 Fluridone, chemical control (plants) Eurasian watermilfoil, 324 giant salvinia, 329 hydrilla, 334 Fluroxypry, chemical control (plants) lantana, 521 Flying carp. See Silver Carp Forbs, 344–431 American species invasive abroad, 695 ISSG 100 worst invaders, 710–11 noxious designation, 690–91 Formosan Subterranean Termite, xix (v. 1), xxiv (v. 1), xxvt (v. 1), 131–34 ISSG 100 worst invaders, 134, 711 state-by-state occurrences, 295–98, 300, 302, 305, 307, 308 Fosamine, chemical control (plants) multiflora rose, 525 Fountain grass, impacts, 679, 683 noxious designations, 667, 691. See also Crimson Fountain Grass Fragrant honeysuckle. See winter honeysuckle French broom, 496, 498, 499 noxious designation, 666, 667, 670, 692. See also Brooms French tamarisk, 579, 580, 582. See also Tamarisk Freshwater herring, 157 Fringecup, 370, 651 Frog’s-bit family, 331 FST. See Formosan Subterranean Termite Fuitour’s-grass. See Leafy Spurge Fund for Animals, animal welfare group, 271 Fungi, 11–35 American species invasive abroad, 697 Fungi, biological control (plants) Asiatic sand sedge, 439 Australian pine, 543 buffelgrass, 439

INDEX n 741 Canada thistle, 349 cheatgrass, 443 chocolate vine, 596 cogongrass, 447 common mullein, 357 common reed, 447 cordgrasses, 458 dyer’s woad, 365 Eurasian watermilfoil, 325 fire tree, 557 Japanese hops, 621 kikuyugrass, 481 Koster’s curse, 518 kudzu, 625 paper mulberry, 564 silk tree, 575 tree of heaven, 589 tropical soda apple, 533 velvet tree, 592 waterhyacinth, 342–43 West Indian marshgrass, 492 winter creeper, 643–44 yellow starthistle, 431 Furze. See Gorse Fusarium nivale, biological control (plants) cheatgrass, 443 Fusarium oxysporum, biological control (plants) tree of heaven, 589 Fusarium oxysporum f. perniciosum. See mimosa wilt Galarhoeus esula, biological control (plants). See Leafy Spurge Galerucella species, biological control (plants) purple loosestrife, 417 water chestnut, 338 Gallerucida bifasciata, biological control (plants) Japanese knotweed, 390 Gallina de palo, 221 Gambusia affinis. See Mosquitofish Gambusia holbrooki. See Mosquitofish Garlic Mustard, 51, 369–72, 507 impacts, 682 noxious designation, 665, 666, 668, 669, 670, 671, 690 pathways of introduction, 675, 676 Gateway National Recreation Area, 435 Genista junceum. See Brooms Genista monspessulana. See French Broom Geomyces destructans. See Bat White-Nose Syndrome Fungus Georgia bully, 600, 657 Geraldton carnation weed, 396, 651 German trout. See Brown Trout

Giant African land snail. See Giant African Snail Giant African Snail, 64–67 state-by-state occurrences, 298 Giant air plant, 600, 651 Giant Asian dodder. See Japanese Dodder Giant cow-parsnip. See Giant Hogweed Giant Hogweed, 372–76 impacts, 678, 681, 682 noxious designation, 665, 666, 668, 669, 670, 671, 690 pathways of introduction, 673, 676 Giant knotweed, 388, 651, noxious designation, 666, 670, 671, 690 Giant Reed, 449, 462–66 impacts, 679, 681, 683, 686 ISSG 100 worst invaders, 710 noxious designation, 671, 691 pathways of introduction, 673, 675 uses of, 465. See also Common Reed Giant reedgrass. See Common Reed Giant Salvinia, 326–30 impacts, 681, 682, 685 noxious designation, 665, 666, 668, 669, 670, 671 pathways of introduction, 674, 677 Giant tree frog. See Cuban Treefrog Giant whiteweed. See Perennial Pepperweed Giant wild pine, 600, 651 Gill-over-the-ground. See ground ivy Ginger family, 391 Ginger-lily. See white ginger Ginseng family, 602 Gizzard Shad, 164, 165, 168–71 state-by-state occurrences, 295, 296, 299, 300, 302, 303, 306, 308, 310 Glacier National Park, and white pine blister rust, 34 Glassy-Winged Sharpshooter, xxvit (v. 1), 134–38 state-by-state occurrences, 296 Globe artichoke, 651 and Canada thistle, 348 Gloger’s Rule, xxxi (v. 1) Glorybush, 515, 590, 657 and Koster’s curse, 515 Glut herring. See Alewife Glyphosate, chemical control (plants) Asiatic sand sedge, 435 Australian pine, 543 Brazilian peppertree, 547 brooms, 501 buffelgrass, 439 Canada thistle, 348 carrotwood, 550

742 n INDEX cheatgrass, 443 chinaberry, 554 Chinese lespedeza, 352 chocolate vine, 596 climbing ferns, 601 cogongrass, 446 common mullein, 356 common reed, 451 English ivy, 605 exotic bush honeysuckles, 506 field bindweed, 609 fig buttercup, 368 fire tree, 557 garlic mustard, 371 giant hogweed, 375 giant reed, 465 giant salvinia, 329 gorse, 511 goutweed, 379 halogeton, 382 ice plant, 386 Japanese barberry, 514 Japanese honeysuckle, 617 Japanese hops, 621 Japanese knotweed, 390 Japanese stiltgrass, 469 Johnsongrass, 472 jubata grass, 477 kikuyugrass, 481 Koster’s curse, 518 kudzu, 625 lantana, 521 leafy spurge, 398 medusahead, 484 melaleuca, 561 mile-a-minute, 628 multiflora rose, 525 musk thistle, 403 Oriental bittersweet, 632 pampas grass, 477 papermulberry, 564 perennial pepperweed, 409 porcelainberry, 635 prickly Russian thistle, 413 princess tree, 568 purple loosestrife, 417 quackgrass, 488 rattlebox, 529 silk tree, 575 swallow-worts, 640 tamarisk, 584 toadflax, 426 tree of heaven, 588 tropical soda apple, 534

waterhyacinth, 342 West Indian marsh grass, 492 winter creeper, 643 wisteria, 647 yellow Himalayan raspberry, 538 Glysine sinensis. See Chinese Wisteria Goats and brooms, 501 and fire tree, 557 and gorse, 511 plants toxic to, 360 Gold clam. See Asian clam Golden Apple Snail, xxiiit (v. 1), 67–70 ISSG 100 worst invaders, 69, 711 state-by-state occurrences, 296, 297, 298, 308 Golden shad. See Alewife Golden starthistle. See Yellow Starthistle Golden star tunicate, 40 Golpar, 374 Gooseberries, White Pine Blister Rust alternate host, 30, 32, 34 Goosefoot family, 379, 409 Gopher plant. See caper spurge Gopher tortoise, 228, 663 and Australian pine, 543 and cogon grass, 446 Gorse, 508–12 and brooms, 498 impacts, 680, 683 ISSG 100 worst invaders, 710 noxious designation, 666, 667, 670, 671, 692 pathways of introduction, 673, 675 Goutweed, 376–79 impacts, 682 noxious designation, 666, 668, 671, 690 pathways of introduction, 673 Gracula religiosa, 233 Graminoids, 432–92 American species invasive abroad, 696 herbicides, xx (v. 2) ISSG 100 worst invaders, 710 noxious designation, 691–92 Grape family, 633 Grape honeysuckle, 505, 657 Grape industry threat, Glassy-Winged Sharpshooter, 137 Grass Carp, 164, 172–75 Hydrilla control, 334 state-by-state occurrences, 296, 300, 302, 307, 308 Grass Carp, biological control (plants) Eurasian watermilfoil, 325 hydrilla, 334 waterhyacinth, 342

INDEX n 743 Grass family, 435, 439, 443, 447, 452, 458, 462, 466, 469, 473, 478, 481, 485, 489 Grasshoppers, biological control (plants) cheatgrass, 443 Chinese lespedeza, 353 Gratiana boliviana, biological control (plants) tropical soda apple, 534 Gray, Asa water chestnut cultivation, 336 Gray herring. See Alewife Gray thistle. See wavyleaf thistle Grazing, physical control (plants) brooms, 501 giant hogweed, 375 kudzu, 625 medusahead, 484 spotted knapweed, 420 tree of heaven, 588 yellow starthistle, 430 Greater celandine. See celandine Great Lakes, xxiv (v. 1), xxvii (v. 1), xxix (v. 1), xxx (v. 1) alewives, 157, 158, 159 Eurasian watermilfoil, 325 gizzard shad, 169 impacts of sea lamprey, 193 musk thistle, 402 New Zealand mud snail, 73, 74 quagga mussel, 76, 77, 78 round goby, 187, 189, 190, 193 sea lamprey, 191 spiny water flea, 96, 97 threat from bighead carp, 165, 166 tubenose goby, 188 water chestnut, 335, 336, 337 zebra mussel, 82, 83, 86 Great shipworm. See Naval Shipworm Great Smoky Mountains National Park, and hemlock woolly adelgid, 143, 145 and feral pigs, 279 Green anaconda, 220 Green comet milkweed, and white swallow-wort, 637, 651 Green Crab, xxxi (v. 1), 90–92 state-by-state occurrences, 296, 297, 300, 301, 304, 305, 306, 307, 309 Greenheart. See coffee colubrina Greenhouse frog, 208–9 Green Iguana, 221–25 state-by-state occurrences, 297, 298, 308, 310 Green-lipped mussel. See Asian Green Mussel Green mussel. See Asian Green Mussel

Green peach aphid, 663 and tropical soda apple as host, 533–34 Green sea turtle, 286, 543, 663 Grey worms. See European Earthworms Grinnell, Joseph, xxxi (v. 1) Ground elder. See Goutweed Ground ivy, 367, 651 Gully-bean. See turkey berry GWSS. See Glassy-winged Sharpshooter Gypsy Moth, xix (v. 1), xxivt (v. 1), xxvt (v. 1), 138–42 ISSG 100 worst invaders, 711 state-by-state occurrences, 295–97, 299, 300, 301, 303, 304, 305, 307–10 Gymnancyla canela, biological control (plants) prickly Russian thistle, 413 Gymnaetron tetrum, biological control (plants) common mullein, 357 Gynerium argentium. See Pampas Grass Gynerium jubatum. See Jubata Grass Hack-and-squirt, herbicide application, xx (v. 2) Haghighat, Sahar, exotic bush honeysuckle study, 507 Hairy lespedeza. See Chinese Lespedeza Hairy wheatgrass, 487, 654 Hairy whitetop, 406, 651 noxious designation, 665, 666, 667, 670, 671, 672, 690 Haleakala National Park, and Argentine ants, 110, 112 Halogeton, 379–83 impacts, 678, 680, 682 noxious designation, 665, 666, 667, 669, 670, 690 pathways of introduction, 677 and Russian thistle, 412 Halogeton glomeratus. See Halogeton Haloragaceae. See watermilfoil family Halloween lady beetle. See Multicolored Asian Lady Beetle Hall’s honeysuckle, 614, 660 Halyomorpha halys. See Brown Marmorated Stink Bug Harmonia axyridis. See Multicolored Asian Lady Beetle Harold L. Lyon Arboretum, velvet tree, 590 Harris mud crab, 87 Hart’s tongue fern, 639, 651 Hawaiian blackberry, 536, 657 Hawai’i Volcanoes National Park and feral goats, 270 and fire tree, 555, 556

744 n INDEX and kahili ginger, 392, 393, 394 and yellow Himalayan raspberry, 538 Hawkmoth, biological control (plants) leafy spurge, 398 Heartleaf horsenettle, 532, 651 Heart-podded hoary cress. See Hoary Cress Hedera helix. See English Ivy Hedge false bindweed, 607, 660 Hedge garlic. See Garlic Mustard Hedychium gardnerianum. See Kahili Ginger Hemlock Woolly Adelgid, xix (v. 1), xxvit (v. 1), 142–45 state-by-state occurrences, 297, 298, 300, 301, 307–9 Hemp family, 618 Hemp sesbania, 528 noxious designation, 665, 690, 692 Herbicide control. See species entries Herbicides application methods, xx (v. 2) major categories, xx (v. 2) Heracleum mantegazzianum. See Giant Hogweed Heracleum species. See Giant Hogweed Herpestes javanicus. See Indian Mongoose Herpetogramma licarsicalis, biological control (plants) kikuyugrass, 481 Heteranthera formosa. See Waterhyacinth Heterodera sinensis, biological control (plants) cogongrass, 447 Heteroperreyia hubrichi, biological control (plants) Brazilian peppertree, 548 Hexazinone, chemical control (plants) Brazilian peppertree, 547 buffelgrass, 439 crimson fountain grass, 462 giant salvinia, 329 Highway ice plant. See Ice Plant Hildebrand, Dr. William, 233 Hill Myna, 233 Himalayan blackberry, 537, 657 noxious designation, 670, 692 pathways of introduction, 676 Himalayan bush clover. See Chinese Lespedeza Histoplasma capsulatum, Rock Pigeon as host, 258 HIV, xix (v. 1) Hive death, honeybee tracheal mite as cause, 99, 100 Hoary Cress, 404–9 pathways of introduction, 677 “Hogzilla,” Georgia wild pig, 277 Hoh River, Japanese knotweed, 389

Hojo-e, Buddhist captive animal release ceremony, 165 Holcus halapensis. See Johnsongrass Hollyhock bindweed. See mallow bindweed “Hollywood Finches,” 241 Homalodisca vitripennis. See Glassy-Winged Sharpshooter Homogenization, of biota, xxviii–xix (v. 1) Honey bee, 663 and gorse, 511. See also Asian honey bee Honeybee Tracheal Mite, xix (v. 1), 99–102 state-by-state occurrences, 295–310 Honeycreepers, Hawaii, xxvii (v. 1), 1–3, 217, 247, 261 Honeylocust, 574, 659 Honeysuckle family, 502, 614 Honeysuckle. See Exotic Bush Honeysuckles; Japanese Honeysuckle Honeyvine, 637, 660 Hordeum caput-medusae. See Medusahead Horn nut. See devil pod Horned water chestnut. See Water Chestnut Horses, plants toxic to buffelgrass, 438 common St. Johnswort, 360 field bindweed, 609 Johnsongrass, 472 rattlebox, 529 yellow starthistle, 430 Horsetail tree. See Australian Pine Hottentot fig. See Ice Plant House cat. See Feral Cat House Finch, xiii (v. 1), 240–43 state-by-state occurrences, 295–310 House Mouse, 281–83 ISSG 100 worst invaders, 712 state-by-state occurrences, 295–10 House Myna. See Common Myna House rat. See Black Rat House Sparrow, xviii (v. 1), xxiiit (v. 1), xxxi (v. 1), 1, 238, 241, 243–46 state-by-state occurrences, 295–310 Human factor in species invasions, xxxii (v. 1) Humboldt Bay, smooth cordgrass eradication, 458 Humboldt Bay owl’s clover, 457, 651 Humulus japonicus. See Japanese Hops Humulus scandens. See Japanese Hops Hyadaphis tatariacae, biological control (plants) exotic bush honeysuckles, 507 Hybridization, impacts, xxviii (v. 1) Hydrellia species, biological control (plants) hydrilla, 334

INDEX n 745 Hydrilla, xviii (v. 1), xxx (v. 1), 173, 331–35, 336 impacts, 681, 682, 685 noxious designation, 665, 66, 667, 668, 669, 670, 671, 689 pathways of introduction, 674, 677 Hydrilla verticillata. See Hydrilla Hydrocharitaceae. See frog’s-bit family Hyles euphorbiae. See hawkmoth Hylobius transversovittatus, biological control (plants) purple loosestrife, 417 Hymenachne acutigluma. See West Indian Marsh Grass Hymenachne amplexicaulis. See West Indian Marsh Grass Hypena srigata, biological control (plants) lantana, 521 Hypericum perforatum. See Common St. Johnswort Hyperparathyroidism disease, in horses, 438 Hypophthalmichthys molitrix. See Silver Carp Hypophthalmichthys nobilis. See Bighead Carp ‘Inia. See Chinaberry Iberian knapweed, 419, 651 noxious designation, 665, 666, 669, 670, 690 Iberian starthistle, 428, 651 Ice Plant, 383–87 impacts, 683 noxious designation, 690 pathways of introduction, 675 Ice plant scale insects, biological control (plants) ice plant, 386 Iguana iguana. See Green Iguana Imazapic, chemical control (plants) cheatgrass, 443 dyer’s woad, 365 Japanese stilt grass, 469 Imazapyr, chemical control (plants) Brazilian peppertree, 547 chinaberry, 554 climbing ferns, 601 cogongrass, 446 common reed, 447 cordgrasses, 457 exotic bush honeysuckles, 506 hoary cress, 409 jubata grass, 477 kahili ginger, 394 lantana, 521 mile-a-minute, 628 melaleuca, 561

pampas grass, 477 perennial pepperweed, 409 silk tree, 575 tamarisk, 584 tropical soda apple, 534 west Indian marshgrass, 492 yellow Himalayan raspberry, 539 Imperata arundinaceae. See Cogongrass Imperata cylindrica. See Cogongrass Imperata cylindrica var. major. See Cogongrass Indian lilac. See Chinaberry Indian Mongoose, xviii (v. 1), xxiiit (v. 1), xxvi (v. 1), 284–86 ISSG 100 worst invaders, 285, 712 state-by-state occurrences, 298, 310 Indian Myna. See Common Myna Indian snakewood. See Asiatic Colubrina Indian star vine. See Hydrilla Indigo snake, 446, 663 Infectious diseases, xxiiit (v. 1) Influenza, xix (v. 1) Injurious animal species, definition, xv (v. 1) Insects, 106–56 American species invasive abroad, 696 Insects, biological control (plants), xviii (v. 2), xix (v. 2) Australian pine, 543 Brazilian peppertree, 547–48 brooms, 501–2 Canada thistle, 348–49 climbing ferns, 601 common mullein, 357 common reed, 451 common St. Johnswort, 361 Eurasian watermilfoil, 324–25 field bindweed, 609 fire tree, 557 garlic mustard, 372 giant hogweed, 375 giant reed, 466 giant salvinia, 330 gorse, 511 halogeton, 383 hoary cress, 409 hydrilla, 334 ice plant, 386 Japanese hops, 621 Japanese knotweed, 390 kikuyugrass, 481 Koster’s curse, 518 kudzu, 625 lantana, 521 leafy spurge, 398–99 mile-a-minute, 628–29

746 n INDEX melaleuca, 561 multi-flora rose, 526 musk thistle, 403 perennial pepperweed, 409 prickly Russian thistle, 413 purple loosestrife, 417 rattlebox, 529 spotted knapweed, 421 strawberry guava, 578–79 swallow-wort, 640 tamarisk, 585 toadflax, 426 tropical soda apple, 534 waterhyacinth, 342–43 west Indian marsh grass, 492 yellow starthistle, 43–31. See also flies, beetles, butterflies, midges, mites, wasps, and weevils Intentional pathways of introduction, xxiiit–xxivt (v. 1) Intermediate wheatgrass, 484, 654 International Biosphere Reserve, Everglades, 560 International Maritime Organization, 708 International Plant Protection Convention (IPPC), 700, 707 Introduced species, xiv (v. 1) Invasion process, xx–xxii (v. 1) Invasion science, xxx–xxxi (v. 1) Invasive plants American species abroad, 695–96 impacts of, xviii (v. 2), 678–86 introduction of, xvii–xviii (v. 2), 673–77 management, xix (v. 2) noxious designation, 665–71, 689–93 organizations and publications concerning, 687–88 problem of, xviii (v. 2) reproduction/dispersal, xvii (v. 2) Invasive species animal problem extent, xviii–xx (v. 1) definitions, xiii–xv (v. 1) ecological impacts, xxvi–xxvii (v. 1) economic impacts, xxix–xxxi (v. 1) federal legislation and agreements pertaining to, 699–706 human factor, xxxii (v. 1) international agreements and conventions pertaining to, 707–9 natural ecosystem impacts, xxvii–xxix (v. 1) pathways of introduction, xxii–xxvi (v. 1) plant problem extent, xv–xviii (v. 1) process, xx–xxii (v. 1)

public health and well-being impacts, xxx (v. 1) Invasive Species Specialist Group (ISSG)100 worst invasive alien species, 710–12 Invertebrates, 36–156 American species invasive abroad, 696–97 Annelid Worms, 48–53 Bryozoan, 36–38 Cnidarian, 45–48 ISSG 100 worst invaders, 711 Mollusks, 53–86 Tunicates, 39–45 Ioxodes scapularis. See Black-legged tick Ipomoea species. See pipevine and Dutchman’s pipe Irish furze. See Gorse Irish ivy. See Atlantic ivy Ironwood. See Australian Pine Isatis tinctoria. See Dyer’s Woad Ischnodemus variegatus. See myakka bug Island applesnail, 67 Italian thistle, 346, 401, 651 noxious designation, 665, 666, 667, 670, 671, 690 Jack-by-the-hedge. See Garlic Mustard Jacob’s ladder. See Yellow Toadflax Jacob’s staff. See Common Mullein Jamaican giant anole, 223 Japanese arrowroot. See Kudzu Japanese bamboo. See Japanese Knotweed Japanese barberry, 51, 512–15 impacts, 683 noxious designation, 666, 668, 692 pathways of introduction, 673, 674 Japanese Beetle, xxvit (v. 1), 146–48 state-by-state occurrences, 295–310 Japanese blood grass. See Cogongrass Japanese brome, 440, 654, 692 Japanese Climbing Fern, 597–602 noxious designation, 665, 667, 693 pathways of introduction, 673 Japanese creeper. See Boston ivy Japanese Dodder, 610–14 in medicine, 613 impacts, 678, 684, 685 noxious designation, 665, 666, 667, 668, 669, 670, 671 Japanese fleece flower. See Japanese Knotweed Japanese Honeysuckle, 614–18, 641–42 impacts, 684, 685 noxious designation, 666, 668, 669, 671, 693 pathways of introduction, 673 Japanese hop. See Japanese Hops

INDEX n 747 Japanese Hops, 618–21 impacts, 681, 684 noxious designation, 666, 668, 693 pathways of introduction, 673, 675 Japanese Knotweed, 387–91 impacts, 681, 682, 685 ISSG 100 worst invaders, 710 noxious designation, 665, 666, 668, 669, 670, 671, 690 pathways of introduction, 673, 675 uses of, 390 Japanese lady beetle. See Multicolored Asian lady beetle Japanese millet, biological control (plants) purple loosestrife, 417 Japanese mitten crab, 87 Japanese mystery snail. See Chinese Mystery Snail Japanese oyster, 40 Japanese sedge. See Asiatic Sand Sedge Japanese Silver-eye, 556 Japanese Stilt Grass, 466–69 impacts, 683 noxious designation, 665, 666, 668, 691 pathways of introduction, 676 Japanese White-Eye, xviii (v. 1), 246–48 and kahili ginger, 393 state-by-state occurrence, 298 and strawberry guava, 578 and velvet tree, 591 Japanese wisteria. See Wisteria Jenkin’s spire shell. See New Zealand Mud Snail Jesup’s milkvetch, 651 and swallow-worts, 639 Johnson, Velma B. (“Wild Horse Annie”), 273 Johnson grass. See Johnsongrass Johnsongrass, 469–72 impacts, 678, 679, 680, 681, 683, 685 noxious designation, 667, 668, 670 pathways of introduction, 675 Jointed grass, 467, 654 Jubata Grass, 472–77 impacts, 679, 683, 685 noxious designation, 667, 691 pathways of introduction, 673 Kahila garland lily. See Kahili Ginger Kahili. See Kahili Ginger Kahili Ginger, 391–94 impacts, 681, 682 ISSG 100 worst invaders, 710

noxious designation, 690 pathways of introduction, 673 Kariba weed. See Giant Salvinia Karritree. See Princess Tree Kelp destruction, Lacy Crust Bryozoan, 37 Kerr, Dr. Warwick, 106 Key West quail-dove, 285 Kiger mustang, 272 Kikuyugrass, 462, 478–81 impacts, 678, 679, 680 noxious designation, 665, 666, 668, 669, 670, 671, 690 pathways of introduction, 675 Killer bee. See Africanized Honey Bee King, Helen Dean, 289 Klamath weed. See Common St. Johnswort Knight anole, 223 Knobbed whelk, 80 Koa tree, 659 and fire tree, 556 and strawberry guava, 577 and velvet tree, 590 Kochia. See burning bush Koi kandy. See Giant Salvinia Koster’s Curse, 209, 515–18, 589 impacts, 683 ISSG 100 worst invaders, 710 noxious designation, 667, 692 pathways of introduction, 673, 674, 677 and velvet tree, 589 Kraunhia floribunda. See Japanese Wisteria Kraunhia floribunda var. alba. See Japanese Wisteria Kraunhia floribunda var. sinensis. See Chinese Wisteria Kraunhia japonica. See Japanese Wisteria Kraunhia sinensis. See Chinese Wisteria Kudzu, 622–26 impacts, 684 ISSG 100 worst invaders, 710 and Japanese dodder, 611, 612 noxious designation, 666, 667, 668, 670, 671, 693 pathways of introduction, 674, 675 uses of, 624, 625 Kyack. See Alewife Kyasuma grass, 459, 461, 654 noxious designation, 665, 666, 668, 669, 670, 671, 691 Lace bug, biological control (plants) Canada thistle, 349 lantana, 521 Lacey Act, xvi (v. 1), 196, 200, 319, 699, 704

748 n INDEX Lacy Crust Bryozoan, xv (v. 1), xxiv (v. 1), 36–38 state-by-state occurrences, 297, 300, 301, 303, 306 Lagurus cylindricus. See Cogongrass Lake lamprey. See Sea Lamprey Lamprey eel. See Sea Lamprey Land invertebrate, ISSG 100 worst invaders, 711 Lantana, 234, 248, 518–22 impacts, 678, 679, 680, 681, 683, 685 ISSG 100 worst invaders, 710 noxious designation, 692 pathways of introduction, 674 uses of, 522 Lantana aculeate. See Lantana Lantana camara. See Lantana Lantana camara var. aculeata. See Lantana Lantana camara var. nivea. See Lantana Lantana wildtype. See Lantana Lardizabala family, 594 Lardizabalaceae. See lardizabala family Large St. Johnswort, 358, 651 Large-headed sedge, 432, 654 Largeleaf lantana. See Lantana Larinus curtus, biological control (plants) yellow starthistle, 431 Larinus minutus, biological control (plants) spotted knapweed, 421 Larinus planus, biological control (plants) Canada thistle control, 348 Latherleaf. See Asiatic Colubrina Laycock, George, xxxi (v. 1) Leaf-blotching bug, biological control (plants) melaleuca, 561 Leaf rust, biological control (plants) pepperweed, 409 Leaf worms. See European Earthworms Leafy Spurge, 395–99 impacts, 678, 680, 681, 682 ISSG 100 invasive worst, 710 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 690 pathways of introduction, 677 Least Bell’s Vireo, 662 and giant reeds, 464 and Japanese dodder, 612 Least Tern, 255, 662 and Asiatic sand sedge, 434 Legless red mealybug, biological control (plants) common reed, 451 Legume family, 527. See also pea family Leiopython albertisii, 220 Lens-pod hoary cress, 405, 651 noxious designation, 690

Lepidium draba. See Hoary Cress Lepidium latifolium. See Perennial Pepperweed Leptinotarsa texana, biological control (plants) tropical soda apple, 534 Leptospirosis, Norway Rat as host, 290 Lespedeza cuneata. See Chinese Lespedeza Lespedeza juncea var. sericea. See Chinese Lespedeza Lespedeza sericea. See Chinese Lespedeza Lespedeza webworm, Chinese lespedeza control, 353 Lesser celadine. See Fig Buttercup Leucantha solstitialis. See Yellow Starthistle Leucoptera spartifolilella, biological control (plants) brooms, 501 Linaria dalmatica ssp. dalmatica. See Dalmatian Toadflax Linaria genistifolia ssp. dalmatica. See Dalmatian Toadflax Linaria vulgaris. See Yellow Toadflax Linepithema humile. See Argentine Ant Linnet. See House Finch Lionfish, xxiiit (v. 1), 175–78 state-by-state occurrences, 297, 298, 305, 307 Liothrips urichi, biological control (plants) Koster’s curse, 518 Lipara species, biological control (plants) common reed, 451 Lithobates catesbeianus. See American Bullfrog Lithracus atronotatus, biological control (plants) Brazilian peppertree, 548 Little, Clarence Cook, 282 Littleleaf sensitive briar, 574, 660 Littoraria irrorata. See marsh periwinkle Littorina littorea. See Common Periwinkle Littorina saxatilis. See Rough Periwinkle Lius peisodon, biological control (plants) Koster’s curse, 518 Lumbricus rubellus. See European Earthworms Lumbricus terretris. See European Earthworms Lonicera insularis. See Exotic Bush Honeysuckles Lonicera japonica. See Japanese Honeysuckle Lonicera maackii. See Amur Honeysuckle Lonicera morrowiii. See Morrow’s Honeysuckle Lonicera sibirica. See Exotic Bush Honeysuckles Lonicera tatarica. See Tatarian honeysuckle Lonicera x bella. See Bell’s Honeysuckle Lonicera japonica. See Japanese Honeysuckle Loosestrife family, 414 Lophyrotoma zonalis, biological control (plants) melaleuca, 561 Louis’ swallow-wort. See Black Swallow-Wort

INDEX n 749 Love-apple. See cockroach berry Lygodiaceae. See climbing fern family Lygodium japonicum. See Japanese Climbing Fern Lygodium microphyllum. See Old World Climbing Fern Lygodium scandens. See Old World Climbing Fern Lymantria dispar. See Gypsy Moth Lymantria xylina, biological control (plants) Australian pine, 543 Lyme Disease Bacterium, xix (v. 1), xxx (v. 1), 3–7 state-by-state occurrences, 296, 298, 299, 300. 301, 304, 306–10 Lythraceae. See loosestrife family Lythrum salicaria. See Purple Loosestrife MacArthur, Robert, xxxi (v. 1) Maccartney rose, 523, 657 Machineel, 495, 659 Madwoman’s milk, 396, 651 Magainins, African Clawed Frog, 204 Magur. See Walking Catfish Mahogany family, 551 Mahogany flat. See Common Bed Bug Mallow bindweed, 607, 661 Malta starthistle, 427, 651 noxious designation, 669, 690 Mammals, 259–94 American species invasive abroad, 697 ISSG 100 worst invaders, 712 Mangosteen family, 358 Mangroves, 548, 550 Marine vomit. See Colonial Tunicate Marlahan mustard. See Dyer’s Woad Marsh marigold, 367, 651 Marsh periwinkle, biological control (plants) cordgrass, 458 Mecinnus janthirus, biological control (plants) toadflax, 426 Medusae, jellyfish generation, 46, 47 Medusahead, 481–84 and cheatgrass, 442, impacts, 679, 680, 683, 691 noxious designation, 666, 670, 671 pathways of introduction, 677 Medusahead wildrye. See Medusahead Megamelus species, biological control (plants) waterhyacinth, 342 Megastigmus aculeatus var. nigroflavus, biological control (plants) multiflora rose, 526

Megastigmus transvaalensis, biological control (plants) Brazilian peppertree, 548 Me-jiro. See Japanese White-Eye Melaleuca, 557–61 impacts, 680, 681, 684 ISSG 100 worst invaders, 710 noxious designation, 665, 666, 668, 669, 670, 671, 692 pathways of introduction, 674, 675, 666 Melaleuca quinquenervia. See Melaleuca Melaleuca species. See Melaleuca Melastoma elegans. See Koster’s Curse Melastoma hirta. See Koster’s Curse Melastoma hirtum. See Koster’s Curse Melastomataceae. See melastome family Melastome family, 515, 589 Meliaceae. See mahogany family Melia species. See Chinaberry Melia azedarach. See Chinaberry Melopsitticus undulates. See Budgerigar Membranipora membranacea. See Lacy Crust Bryozoan Mesembryanthemum crystallinum. See Crystalline Ice Plant Mesembryanthemum edule. See Ice Plant Metriona elatior, biological control (plants) tropical soda apple, 534 Metrosideros quinquenervia. See Melaleuca Metsulfuron, chemical control (plants) climbing ferns, 601 common St. Johnswort, 361 dyer’s woad, 365 halogeton, 382 hoary cress, 409 Japanese hops, 621 yellow Himalayan raspberry, 539 Metzneria paucipunctella, biological control (plants) spotted knapweed, 421 Mexican bamboo. See Japanese knotweed Mexican garter snake, 207 Mexican water-fern, 327, 649 Miconia. See Velvet Tree Miconia calvescens. See Velvet Tree Miconia magnifica. See Velvet Tree Microorganisms, 1–10 ISSG 100 worst invaders, 710 Microstegium imberbe. See Japanese Stilt Grass Microstegium vimineum. See Japanese Stilt Grass Midges, biological control (plants) cogongrass, 447 common reed, 451 Eurasian watermilfoil, 324, 325 leafy spurge, 399

750 n INDEX Migratory Bird Treaty Act (2001), 255 Mikania micrantha, 626, 710 Mile-A-Minute, 626–29 impacts, 678, 684, 685 noxious designation, 665, 666, 669, 670, 693. See also Mikania micrantha Mile-a-minute weed. See Mile-A-Minute Milfoil midge, biological control (plants) Eurasian watermilfoil, 324 Military grass. See Cheatgrass Milk thistle, 346, 651 Milkweed family, 636 Millettia japonica. See Japanese Wisteria Mimosa. See Silk Tree Mimosa arborea. See Silk Tree Mimosa julibrissin. See Silk Tree Mimosa wilt, biological control (plants) silk tree, 575 Missiongrass, 459–60, 655 Mites, biological control (plants) climbing ferns, 601 field bindweed, 609 gorse, 511 multiflora rose, 526 prickly Russian thistle, 413 waterhyacinth, 342 Mollusks, 53–86 American species invasive abroad, 696 Mompha trithalama, biological control (plants) Koster’s curse, 518 Monarch butterflies, 663 and Asiatic sand sedge, 434 and swallow-worts, 639 Money monitor. See Nile Monitor Monk Parakeet, xxvt (v. 1), xxix (v. 1), 248–52 state-by-state occurrences, 295, 297–300, 304–8, 310 Monogynella japonica. See Japanese Dodder Monopterus albus. See Asian Swamp Eel Montana Dyer’s Woad Cooperative Project, 365 Mooney, H. A., xxxi (v. 1) Moraceae. See mulberry family Morella faya. See Fire Tree Morning glory family, 606 Morrow’s honeysuckle, noxious designation, 666, 668, 669, 671, 692 and Japanese honeysuckle, 614. See also Exotic Bush Honeysuckles Mosquito fern, 327, 329, 650 Mosquitofish, xxiiit (v. 1), 178–82 ISSG 100 worst invaders, 181, 711 state-by-state occurrences, 295–306, 307–10

Mosquitos Asian Tiger, 116–20 as avian malaria vectors, 1, 3 as tularemia vector, 290 as West Nile virus vector, 8, 9, 119 Yellow fever mosquito, 117 Moths, biological control (plants) Australian pine, 543 bindweed, 609 Brazilian peppertree, 547–48 brooms, 501 chocolate vine, 596 climbing ferns, 601 common mullein, 357 common reed, 451 common St. Johnswort, 361 Eurasian watermilfoil, 324–25 field bindweed, 609 fire tree, 557 giant reed, 466 gorse, 511 halogeton, 383 hydrilla, 334 Japanese hops, 621 Koster’s curse, 518 leafy spurge, 398 mile-a-minute, 629 prickly Russian thistle, 413 Russian knapweed, 421 sawtooth blackberry, 539 spotted knapweed, 421 toadflax, 426 velvet tree, 592 waterhyacinth, 342 Moth mullein, 354, 651 Mowing. See cutting Mud shad. See Gizzard Shad Mulberry family, 562 Mulching, tarping, or solarization, physical control (plants) chocolate vine, 596 common reed, 451 cordgrasses, 457 English ivy, 605 field bindweed, 609 goutweed, 379 Japanese knotweed, 390 Johnsongrass, 472 kikuyugrass, 481 West Indian marsh grass, 491 winter creeper, 643 Mulhaden. See Alewife Mullein moth, biological control (plants) mullein, 347

INDEX n 751 Multicolored Asian Lady Beetle, xxiiit (v. 1), xxx (v. 1), 148–52 state-by-state occurrences, 307 Multiflora Rose, 522–26 impacts, 678, 680, 683, 685 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 692 pathways of introduction, 674, 675, 676 Musk Thistle, 345, 348, 399–404 impacts, 680, 683 noxious designation, 666, 667, 668, 669, 670, 671, 672, 690 pathways of introduction, 677 Mus musculus. See House Mouse Mustang. See Feral Horse Mustard family, 362, 369, 404 Mute Swan, 252–56 state-by-state occurrences, 297, 300, 301, 304, 305, 309 Myakka bug, biological control (plants) West Indian marsh grass, 492 Myiopsitta monachus. See Monk Parakeet Myocastor coypus. See Nutria Mycoplasmal conjunctivitis House Finch decline, 241–42 spread, 243 Mylopharyngodon piceus. See Black Carp Myrica faya. See Fire Tree Myricaceae. See sweet gale family Myriophyllum spicatum. See Eurasian Watermilfoil Myriothecium verrucaris, biological control (plants) kudzu, 625 Myrtaceae. See eucalyptus family; myrtle family Myrtle family, 557, 576 Mytella charruana. See Charru mussel Myxobolus cerebralis. See Whirling Disease Nanday Conure (parakeet), 250 Nandayus nenday. See Nanday Conure Nanny shad. See Gizzard Shad Nanophyte species, biological control (plants) water chestnut, 338 Nasturtium draba. See Hoary Cress National Gypsy Moth Slow the Spread (STS) program, 142 National Invasive Species Act, 703 Native species, definitions, xiii (v. 1) Natural selection, and brown anoles, 217 Naval Shipworm, 70–72 Neochetina species, biological control (plants) waterhyacinth, 342

Neodiplogrammus quadrivittatus. See sesbania stem borer Neogobius melanostomus. See Round Goby Neomusotima conspurcatalis, biological control (plants) climbing ferns, 601 Neomusotima fuscolinealis, biological control (plants) climbing ferns, 601 Nepalese browntop. See Japanese Stilt Grass New Zealand Mud Snail, xxvt (v. 1), 73–76 state-by-state occurrences, 295, 296, 298, 302, 303, 306, 308–10 Nicosulfuron, chemical control (plants) quackgrass, 488 Nightcrawler, xxiiit (v. 1), xxxv (v. 1). See also European Earthworms Nigropalallidal encephalomalacia disease, in horses, 430 Nigua. See Koster’s Curse Nile Monitor, xxivt (v. 1), 225–28 state-by-state occurrences, 297 Nintooa japonica. See Japanese Honeysuckle Niphograpta albiguttalis. See waterhyacinth moth Nitrogen fixer Australian pine, 541 brooms, 497, 500 fire tree, 556 gorse, 509–10 kudzu, 623, 627 Russian olive, 571–72 silk tree, 575 Nodding thistle. See Musk Thistle Nonindigenous Aquatic Nuisance Prevention and Control Act (1990), xv (v. 1), 85, 702 Nonnative species, xv (v. 1) Norops sagrei. See Brown Anole Norops sagrei sagrei, 214 Norops sagrei ordinates, 214 North Cascades National Park, and white pine blister rust, 34 Northern African python, 220 Northern pearly eye butterfly, and Japanese stilt grass, 468, 664 Northern Snakehead, xix (v. 1), xxiiit (v. 1), 182–85 state-by-state occurrences, 301, 306, 309 Northern watermilfoil, 321–22, 324, 325, 649 Northern wheatgrass, 487, 655 Norway Rat, xviii (v. 1), xxvit (v. 1), 259, 260, 262, 283, 287–90 state-by-state occurrences, 295–310 Noxious species, definition, xv (v. 1)

752 n INDEX Noxious Weed Control and Eradication Act, 704–5 Nutria, xviii (v. 1), xxiiit (v. 1), xxvi (v. 1), 290–94 ISSG 100 worst invaders, 293, 712 state-by-state occurrences, 295– 298, 300–2, 304–6, 307, 308, 309 Oberea erythrocephala, biological control (plants) leafy spurge, 398 Ohia tree, 556, 659 and strawberry guava, 577, 579 and velvet tree, 591 Old World Climbing Fern, 597–602 impacts, 684 noxious designation, 665, 667, 693 pathways of introduction, 674, 679 Octagonal-tail earthworm. See European Earthworms Oleaster. See Russian Olive Oleaster family, 568 Oncideres cingulata. See twig girdler Onopordum acanthium. See Scotch thistle Oncorhynchus mykiss. See Rainbow Trout Ophideres fullonica, biological control (plants) chocolate vine, 596 Ophioglossum japonicum. See Japanese Climbing Fern Ophiomyia lantanae, biological control (plants) lantana, 521 Ophiostoma novo-ulmi. See Dutch Elm Disease Ophiostoma ulmi. See Dutch Elm Disease Oppositeleaf Russian thistle, 412, 651 noxious designation, 666, 690 Orangeberry nightshade, 532, 661 Orange sheath tunicate. See Chain tunicate Orchids, 495, 661 Orconectes rusticus. See Rusty Crayfish Orconectes virilis. See Virile Crayfish Organ Pipe Cactus National Monument buffelgrass, 437, 438 Oriental Bittersweet, 629–33 impacts, 681, 684 noxious designation, 666, 668, 669, 671, 693 pathways of introduction, 674 and winter creeper, 641 Orseolia javanica, biological control (plants) cogongrass, 447 Orthogalumna terebrantis, biological control (plants) waterhyacinth, 342 Osteopilus septentrionalis. See Cuban Treefrog Ossabaw Island hog, 280

Oxyops vitiosa, biological control (plants) melaleuca, 561 Oyster thief (green algae), 37 Pacific mosquito fern, 327, 649 Painted butterfly, biological control (plants) Canada thistle, 348 Pale Swallow-Wort, 636–40 impacts, 678, 680, 684 noxious designation, 666, 668, 669, 671, 693 pathways of introduction, 674 Palila, and gorse, 510, 662 Pampas Grass, 460, 473–78 impacts, 679, 683, 685 noxious designation, 691 pathways of introduction, 674 Panicum amplexicaule. See West Indian Marsh Grass Paper Mulberry, 562–65 impacts, 681, 684 noxious designation, 693 pathways of introduction, 674 Paperbark tea tree. See Melaleuca Paperbark tree. See Melaleuca Papyrius papyriferus. See Paper Mulberry Parapoynx diminutalis, biological control (plants) hydrilla, 334 Paraquat, chemical control (plants) cheatgrass, 443 medusahead, 484 Parrotfeather, 322, 649 noxious designation, 665, 666, 668, 671, 689 Partridge pea, 574, 651 Pasilla. See Chinaberry Passer domesticus. See House Sparrow Passer montanus, 244 Pasto buffel. See Buffelgrass Pasture rose, 524, 657 Pathways of introduction, xxii–xxvi (v. 1) intentional, xxiiit–xxivt (v. 1) unintentional, xxiiit (v. 1) Paulownia. See Princess Tree Paulownia elongata. See elongate paulownia Paulownia fortunei. See white-flowered paulownia Paulownia imperialis. See Princess Tree Paulownia tomentosa. See Princess Tree Peacock cichlid, 198 Pea family, 349, 496, 508, 527, 572, 622, 644 Peacock fly, biological control (plants) yellow starthistle, 431 Pearl millet, 462, 655

INDEX n 753 Pempelia genistella, biological control (plants) gorse, 511 Pennisetum ciliare. See Buffelgrass Pennisetum clandestinum. See Kikuyugrass Pennisetum conchroides. See Buffelgrass Pennisetum inclusum. See Kikuyugrass Pennisetum incomptum. See Buffelgrass Pennisetum longstylum. See Kikuyugrass Pennisetum longstylum var. clandestinum. See Kikuyugrass Pennisetum macrostachyon. See Crimson Fountain Grass Pennisetum rueppelianum. See Crimson Fountain Grass Pennisetum ruppelii. See Crimson Fountain Grass Pennisetum setaceum. See Crimson Fountain Grass Peppervine, 633, 634, 660, 661 noxious designation, 693. See also Porcelainberry Pepperweed whitetop. See Hoary Cress Perennial peppergrass. See Hoary Cress Perennial Pepperweed 404–9 impacts, 680, 683 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672 pathways of introduction, 677 Perennial snapdragon. See Yellow Toadflax Perna viridis. See Asian Green Mussel Persian ivy. See colchis ivy Persian lilac. See Chinaberry Persicaria arifolium var. perfoliatum. See Mile-A-Minute Persicaria perfoliata. See Mile-A-Minute Peruvian peppertree, 545, 659 Pet trade release boa constrictors, 220 Burmese Python, 219 Common Myna, 233 Nile Monitor, 226 Petromyzon marinus. See Sea Lamprey Phakopsora apoda, biological control (plants) kikuyugrass, 481 Phalaris setaceum. See Crimson Fountain Grass Phomopsis arnoldiae, biological control (plants) Russian olive tree, 572 Phomopsis broussonetiae, biological control (plants) paper mulberry, 564 Phothedes dulcis, biological control (plants) giant reed, 466 Phragmataecia castaneae, biological control (plants) common reed, 451

Phragmites. See Common Reed Phragmites australis ssp. australis. See Common Reed Phragmites communis. See Common Reed Phragmites communis var. berlandieri. See Common Reed Phragmites phragmites. See Common Reed Phyllachora species, biological control (plants) West Indian marsh grass, 492 Phyllocoptes fructiphilus, biological control (plants) multiflora rose, 526 Phyllonorycter myricae, biological control (plants) fire tree, 557 Phyllorhiza punctata. See Australian Spotted Jellyfish Phyllotreta ochripes, biological control (plants) garlic mustard, 372 Phymatototrichum omnivorum, biological control (plants) common mullein, 357 winter creeper, 643 Physical control (plants). See species entries Phytophthora ramorum. See Sudden Oak Death Piaropus crassipes. See Waterhyacinth Piaropus mesomelas. See Waterhyacinth Pierce’s disease, Glassy-Winged Sharpshooter as vector, 137 Pickerelweed, 342, 649 Pickerelweed family, 339 Picloram, chemical control (plants) Australian pine, 543 chinaberry, 554 common St. Johnswort, 361 gorse, 511 Japanese honeysuckle, 617 Japanese knotweed, 390 leafy spurge, 398 multiflora rose, 525 musk thistle, 403 spotted knapweed, 420 strawberry guava, 578 tropical soda apple, 534 wisteria, 647 Pigface fig. See Ice Plant Piggyback plant, 370, 651 Pilewort. See Fig Buttercup Pili grass, 438, 655 Pimienta de Brazil. See Brazilian Peppertree Pineapple guava. See Strawberry Guava Pine bark adelgid, 31 Pineland lantana, 519, 657 Pineland verbena. See pineland lantana Pine straw, and climbing ferns, 600, 601

754 n INDEX Pineus strobi. See Pine bark adelgid Pineywoods rooter. See Feral Pig Pink-flowered tamarisk. See Tamarisk Pink pampas grass. See Jubata Grass Pink sand verbena, 386, 651 Pink snow mold, biological control (plants) cheatgrass, 443 Pipevine, 594, 661 Piping Plover, 662 and Asiatic sand sedge, 434 and oriental bittersweet, 632 Plains bristlegrass, 437, 655 Planthopper, biological control (plants) cordgrass, 458 waterhyacinth, 342 Plant Protection Act, 704 Plasmodium relictum capistranoae. See Avian Malaria Platycephala planifrons, biological control (plants) common reed, 451 Pleuropterus cuspidatus. See Japanese Knotweed Pleuropterus zuccarinii. See Japanese Knotweed Plowing, physical control (plants). See tilling Plumeless thistle, 401, 652 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 691. See also Musk Thistle Poaceae. See grass family Poison hemlock, 374, 652 Poison ivy, 547, 661 and English ivy, 604 and kudzu, 623 Polygonaceae. See buckwheat family Polygonum cuspidatum. See Japanese Knotweed Polygonum perfoliatum. See Mile-A-Minute Polygonum zuccarinii. See Japanese Knotweed Pomacea canaliculata. See Golden Apple Snail Pomacea insularum. See Island applesnail Pondweed, 333–34, 649 Pontederiaceae. See pickerelweed family Pontederia crassipes. See Waterhyacinth Poor-man’s mustard. See Garlic Mustard Popillia japonica. See Japanese Beetle Porcelain ampelopsis. See Porcelainberry Porcelainberry, 633–36 and English ivy, 603 impacts, 684 noxious designation, 666, 668, 693 pathways of introduction, 674 Porcelain vine. See Porcelainberry Portuguese broom, noxious designation, 670, 692. See also Brooms Postemergent herbicides, xx (v. 2)

Potamopyrgus antipodarum. See New Zealand Mud Snail Potato family, 530 Potato x disease, field bindweed as host, 609 Powderpuff tree. See Silk Tree Proterorhinus marmoratus. See Tubenose goby Preemergent herbicides, xx (v. 2) Prickly glasswort. See Prickly Russian Thistle Prickly lantana. See Lantana Prickly rose, 524, 657 Prickly Russian Thistle, 409–14 and halogeton, 380 impacts, 678, 679, 683, 685 noxious designation, 665, 666, 667, 669, 691 pathways of introduction, 677 Prickly sage. See Lantana Pride of India. See Chinaberry Princess flower. See glorybush Princess Tree, 121, 565–68 impacts, 684 noxious designation, 666, 693 pathways of introduction, 674, 676 uses of, 567 Prokeleisa marginata. See planthopper Prostrate tickrefoil, 623, 652 Pseudocercospora humuli, biological control (plants) Japanese hops, 621 Pseudodaleta unipuncta. See grass army worms Pseudomonas bacteria, biological control (plants) cheatgrass, 443 kudzu, 625 Pseudophilothrips ichini, biological control (plants) Brazilian peppertree, 548 Pseudorabies, Wild Pig as carrier, 280 Psidium cattleianum. See Strawberry Guava Psidium guajava. See common guava Psidium littorale var. longipes. See Strawberry Guava Psylliodes chalcomera, biological control (plants) musk thistle, 403 Pterois miles. See devil firefish. See also Lionfish Pterois volitans. See Lionfish Pt. Reyes bird’s beak, 457, 652 Public health and well-being impacts, xxx (v. 1) Australian pine, 543 chinaberry, 553 English ivy, 605 giant hogweed, 375 Japanese hops, 620 Johnsongrass, 472 leafy spurge, 397 melaleuca, 560 paper mulberry, 563 Public Land Management Act of 2009, 706

INDEX n 755 Puccinia juncea var. solstitialis, biological control (plants) yellow starthistle, 431 Puccinia lygodii, biological control (plants) climbing ferns, 601 Puccinia punctiformis, biological control (plants) Canada thistle, 349 Pueraria montana. See Kudzu Pueraria species. See Kudzu Puerto Rican treefrog. See Coqui Pulvinariella species. See ice plant scale insects Punk tree. See Melaleuca Purple African nightshade, 532, 657 Purpleflowering raspberry, 524, 657 Purple guava. See Strawberry Guava Purple Loosestrife, 414–17 impacts, 681, 683 ISSG 100 invasive worst, 711 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 691 pathways of introduction, 674, 675, 677 Purple lythrum. See Purple Loosestrife Purple pampas grass. See Jubata Grass Purple plague. See Velvet Tree Purple sesbane. See Rattlebox Purple starthistle, 419, 428, 652 noxious designation, 665, 666, 669, 670, 671, 691 Purplestem angelica, 373, 652 Purple strawberry guava. See Strawberry Guava Pyricularia grisea, biological control (plants) buffelgrass, 439 kikuyugrass, 481 Python molurus bivittatus. See Burmese Python Python sebae, 220 Quackgrass, 485–89 impacts, 678, 680, 683 noxious designation, 665, 666, 667, 670, 671, 672, 691 pathways of introduction, 677 Quagga Mussel, xxvt (v. 1), 76–79, 83 state-by-state occurrences, 295, 296, 298–303, 305, 306 Quaker Conure. See Monk Parakeet Quaker Parrot. See Monk Parakeet Quassia family, 585 Queen Anne’s lace, 373, 652 Rabbit flower. See Yellow Toadflax Rainbow Trout, xviii (v. 1), xxivt (v. 1), xxviii (v. 1), 166, 185–87 ISSG 100 worst invaders, 187, 711 state-by-state occurrences, 295–310

Rainbow weed. See Purple Loosestrife Rajania quinata. See Chocolate Vine Ralstonia solanacearum, biological control (plants) kahili ginger, 394 tropical soda, 534 Rambler rose. See Multiflora Rose Ramorum blight. See Sudden Oak Death Rana platernera. See Cuban Treefrog Range expansion, xv (v. 1) Range maps, xiv (v. 1) Ranunculuaceae. See buttercup family Ranunculus ficaria. See Fig Buttercup Rapana venosa. See Veined Rapa Whelk Rattlebox, 527–30 impacts, 679, 681, 682, 683, 685, 692 noxious designation, 692 Rattus norvegicus. See Norway Rat Rattus rattus. See Black Rat Razorback. See Feral Pig Red baron. See Japanese Blood Grass Redbelly tilapia, 196 Red-billed Leiothrix, and kahili ginger, 393, 662 and velvet tree, 591 Redcoat. See Common Bed Bug Red honeysuckle, 505, 657 Red Imported Fire Ant, xxvit (v. 1), xxviii (v. 1), 152–56 ISSG 100 worst invaders, 711 state-by-state occurrences, 295–98, 305, 307–10 Red lionfish. See Lionfish Red mulberry, 562, 659 Red sage. See Lantana Red sesbania. See Rattlebox Red sheath tunicate. See Chain Tunicate Red starthistle. See purple starthistle Red swamp crayfish, 89 Red wigglers. See European Earthworms Red worms. See European Earthworms Rehsonia floribunda. See Japanese Wisteria Rehsonia sinensis. See Chinese Wisteria Reptiles, 214–28 American species invasive abroad, 697 ISSG worst invaders, 712 Residuals, herbicides, xx (v. 2) Reticulated python, 220 Reynoutria. See Japanese Knotweed Reynoutria japonica, 387 Rhamnaceae. See buckthorn family Rhamnus asiatica. See Asiatic Colubrina Rhamnus splendens. See Asiatic Colubrina Rhinocyllus conicus, biological control (plants) Canada thistle, 348 musk thistle, 403

756 n INDEX Rhinoncomimus latipes, biological control (plants) mile-a-minute, 628 Rhinusa species, biological control (plants) toadflax, 426 Rhizedra lutosa, biological control (plants) common reed, 451 Rhizobacteria, biological control (plants) cheatgrass, 443 Rhus terebinthifolia. See Brazilian Peppertree Rhyssomatus marginatus. See sesbania seed weevil Rice eel. See Asian Swamp Eel Rice-paddy eel. See Asian Swamp Eel Richard’s pampas grass. See toe toe RIFA. See Red Imported Fire Ant Ringed Turtle-Dove, 235–36 Rio Grande ragweed, 438, 652 River herring. See Alewife Robust blackberry. See Yellow Himalayan Raspberry Rock Dove. See Rock Pigeon Rock Pigeon, xviii (v. 1), 256–59 state-by-state occurrences, 295–310 Rocky Mountain National Park, chytrid frog fungus, 19 quackgrass, 487 Roof rat. See Black Rat Root rot and Australian pine, 544 and common mullein, 357 and giant reed, 466 and winter creeper, 644 Rosa cathayensis. See Multiflora Rose Rosaceae. See rose family Rosa multiflora. See Multiflora Rose Roseau. See Common Reed Roseau cane. See Common Reed Rose family, 522, 535 Rose stemgirdler, biological control (plants) multiflora rose, 526 Round-leaved bittersweet. See Oriental Bittersweet Rough Periwinkle, 61 Round Goby, xxiv (v. 1), xxvt (v. 1), xxvii (v. 1), 187–90 state-by-state occurrences, 299, 301, 302, 305 Royal paulownia. See Princess Tree Rubus ellipticus. See Yellow Himalayan Raspberry Rubus flavus. See Yellow Himalayan Raspberry Rubus gowreephul. See Yellow Himalayan Raspberry Rugosa rose, 524, 657

Running euonymus. See running strawberry bush Running strawberry bush, 641, 657 Rush wheatgrass, 487, 655 Russian knapweed, 418–19, 428, 652 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 691 toxic, 430 Russian Olive, 568–72, 705 impacts, 680, 682, 684, 686 noxious designation, 666, 669, 693 pathways of introduction, 674, 675, 676 Russian thistle, 380. See Prickly Russian Thistle Russian tumbleweed. See Prickly Russian Thistle Russian wheatgrass, 487, 655 Russian wild boar. See Feral Pig Rusty blackhaw, 641, 657 Rusty Crayfish, xxiiit (v. 1), 93–95 state-by-state occurrences, 297, 299, 300, 301, 302, 304, 306, 309 Ryegrass, 487, 655 Sacramento Mountain thistle, and musk thistle, 402, 652 Safflower, 348, 652 Salicaire. See Purple Loosestrife Salmo trutta. See Brown Trout Salsola species. See Prickly Russian Thistle Salsola tragus. See Prickly Russian Thistle Saltcedar leaf beetle, biological control (plants) tamarisk, 585 Salt cedar. See Tamarisk Saltlover. See Halogeton Saltmarsh clubrush. See cosmopolitan bulrush Salt marsh hay. See Cordgrasses and Their Hybrids Salt meadow cordgrass. See Cordgrasses and Their Hybrids Saltwort. See Prickly Russian Thistle Salvinia. See Giant Salvinia Salvinia auriculata. See Giant Salvinia Salvinia auriculata complex, 326 Salviniaceae. See floating fern family Salvinia molesta. See Giant Salvinia Sameodes albiguttalis. See waterhyacinth moth San Clemente Island goats, 269, 270 Sand dune thistle, 402, 652 Sapindaceae. See soapberry family Sarcotheca bahiensis. See Brazilian Peppertree Sarthamnus scoparius. See Brooms Sassafras, 562, 659 Satintail. See Cogongrass. See also Brazilian satintail; California satintail Sauce-alone. See Garlic Mustard

INDEX n 757 Saussurea species, 402 Sawbelly. See Alewife Sawtooth blackberry, 537, 539, 657 noxious designation, 667, 692 Scaldweed. See common dodder Scaly bark oak. See Australian Pine Scarlet wisteria. See Rattlebox Scheiffelin, Eugene, 238 Schinus. See Brazilian Peppertree Schinus species. See Brazilian Peppertree Schinus terebinthifolius. See Brazilian Peppertree Schistocerca americana, biological control (plants) Chinese lespedeza, 353 Schizaphiz graminum, biological control (plants) giant reed, 466 Schoenobius giganatella, biological control (plants) common reed, 451 Scientific Committee on Problems of Environment (SCOPE), xxxi (v. 1) Sclerotinia sclerotiorum, biological control (plants) Canada thistle, 349 Scolytus multistriatus. See smaller European elm bark beetle SCOPE, xxxi (v. 1) Scotch broom, 509 noxious designation, 666, 667, 670, 671, 692. See also Brooms Scotch thistle, 401, 403, 652 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 691 Scrambling nightshade. See Tampico soda apple Scrophulariaceae. See figwort family Seabeach amaranth, 434, 652 Seabeach evening primrose, 434, 652 Sea-coast marsh elder, 434, 652 Sea fig, 384, 652. See also Ice Plant Sea Lamprey, xxiv (v. 1), xxvt (v. 1), 158, 183, 190–93 state-by-state occurrences, 299, 301, 302, 305, 310 Sea sandwort, 434, 652 Sea-side arrowgrass, 455, 457, 655 Seaside knotweed, 434, 652 Sedge family, 336, 432 Sedges, 455, 546, 654, 655. See also Asiatic Sand Sedge Segmented worms, 48 Selloa. See Jubata Grass Senna obtusifolia, biological control (plants) kudzu, 625 Septoria hodgesii sp. nov, biological control (plants) fire tree, 557 Sericea lespedeza. See Chinese Lespedeza

Sericea bush clover. See Chinese Lespedeza Sericothrips staphylinus, biological control (plants) gorse, 511 Serrate spurge. See toothed spurge Sesbania flower beetle, biological control (plants) rattlebox, 529 Sesbania puniceae. See Rattlebox Sesbania seed weevil, biological control (plants) rattlebox, 529 Sesbania tripetii. See Rattlebox Sesbania stem borer, biological control (plants) rattlebox, 529 Sethoxydim, chemical control (plants) quackgrass, 488 Seven-spotted lady beetle, 149 Sewer rat. See Norway Rat Shattercane. See sorghum Sheep, plants toxic to buffelgrass, 438 common St. Johnswort, 360 halogeton, 382 Johnsongrass, 472 Shenandoah National Park, and gypsy moth, 143 Ship rat. See Black Rat Shortspike watermilfoil. See northern watermilfoil Short-tip gall midge, biological control (plants) leafy spurge, 399 Shrubby nightshade, 532, 657 Shrubby Russian thistle, 412, 657 noxious designation, 665, 666, 667, 668, 669, 670, 671, 692 Shrubs, 493–39 American species invasive abroad, 695 ISSG 100 worst invaders, 710–11 noxious designation, 692 Sicilian starthistle, 427, 652 noxious designation, 665, 666, 691 Silk Tree, 572–75 impacts, 684 noxious designation, 693, pathways of introduction, 674, 676 Silky acacia. See Silk Tree Silky bush clover. See Chinese Lespedeza Silver Carp, 164, 194–96 state-by-state occurrences, 299, 300 Silverberry, 570, 655 Silver buffaloberry, 570, 656 Silverleaf nightshade, 532, 657 noxious designation, 665, 666, 667, 669, 670, 671, 692 Silverleaf whitefly, and tropical soda apple as host, 533–34

758 n INDEX Silver pampas grass. See Pampas Grass Silversword, 356, 657 Silverthorn, 570, 658 Simaroubaceae. See quassia family Simberloff, Daniel, xxxi (v. 1) Sipha species. See sugarcane aphids Sisymbrium alliaria. See Garlic Mustard Sisymbrium officinalis. See Garlic Mustard Skipjack. See Gizzard Shad Slender-flowered thistle, 401, 652 Slender lespedeza, 350–51, 652 Slender perennial peppercress. See Perennial Pepperweed Slender Russian thistle, 411, 652 noxious designation, 665, 666, 691 Slender seapurslane, 434, 652 Slippery mullein. See moth mullein Slow paralysis virus (SPV), bee virus, 105–6 Small Asian mongoose. See Indian Mongoose Small cordgrass, 452, 655. See also Cordgrasses and Their Hybrids Small crowfoot. See Fig Buttercup Smaller European elm bark beetle, 22, 23, 24 Small-flowered morning glory. See Field Bindweed Small-flowered tamarisk. See Tamarisk Small Indian mongoose. See Indian Mongoose Small-leaf climbing fern. See Old World Climbing Fern Smooth brome, 440, 655 noxious designation, 692 Smooth cordgrass. See Cordgrasses and Their Hybrids Smooth cordgrass hybrid. See Cordgrasses and Their Hybrids Smooth rose, 524, 658 Snow-on-the-mountain. See Goutweed Snowpeaks raspberry, 537, 658 noxious designation, 667, 692 Soapberry family, 548 Soap bush. See Koster’s Curse SOD. See Sudden Oak Death Sodom apple. See Tropical Soda Apple Sod-web worm, Canada thistle host, 347 Soft brome, 440, 655 noxious designation, 692 Soft chess. See Cheatgrass Soil Conservation Service. See U.S. Department of Agriculture Soil Conservation Service Solanaceae. See potato family Solanum chloranthum. See Tropical Soda Apple Solanum khasianum var. chatterjeeanum. See Tropical Soda Apple Solanum viarum. See Tropical Soda Apple

Solanum viridiflorum. See Tropical Soda Apple Solarization, physical control (plants). See mulching or tarping Soldierwood, 493, 658 Solenopsis invicta. See Red Imported Fire Ant Solenopsis richteri. See Black imported fire ant Sonoran Desert weedwackers, 438 Sophonia rufostachia. See two-spotted leafhopper Sorghum, 470, 472, 655 Sorghum halepense. See Johnsongrass Sorghum miliaceum. See Johnsongrass Southern house mosquito, as disease vectors, 1, 3, 8, 9 South Texas. See Rio Grande ragweed Soybean loper, 664, and tropical soda apple as host, 533–34 Spanish broom, noxious designation, 667, 670, 671, 692. See also Brooms Spanish gold. See Rattlebox Spanish mustang, 271–72 Spanish reed. See Giant Reed Spartina species. See Cordgrasses and Their Hybrids Spartium junceum. See Brooms Spartium scoparium. See Brooms Speargrass. See Cogongrass Species Survival Commission (SSC), ISSG 100 worst invasive species, 710–12 Sphenophorus entus vestitus, biological control (plants) kikuyugrass, 481 Spiked loosestrife. See Purple Loosestrife Spike watermilfoil. See Eurasian Watermilfoil Spiny Water Flea, xxiv (v. 1), 95–99 state-by-state occurrences, 301, 302, 305, 306, 309 Spirochetes bacterium, 3 Spissistulus festinus. See three-cornered alfalfa leaf hopper Spotted jellyfish. See Australian Spotted Jellyfish Spotted knapweed, 417–21 impacts, 679, 680, 683 noxious designatioins, 665, 666, 667, 668, 669, 670, 671, 672, 691 pathways of introduction, 677 Spotted Tilapia, 196–98 state-by-state occurrences, 296, 297, 303. See also European Starling Spurge family, 395 Spurgia esulae. See short-tip gall midge Spurious mullein. See moth mullein Squarrose knapweed, 419, 652 noxious designation, 665, 666, 670, 671, 691 Staff-tree family, 629

INDEX n 759 Staff-vine family, 640 Staghorn sumac, 586, 658 Star thistles, 402. See also Yellow Starthistle St. Augustine grass, 479, 655 St. Barnaby’s thistle. See Yellow Starthistle Steele, Dr. Allen, 4 Steelhead (coastal rainbow trout), 185, 186 St. Johnswort. See Common St. Johnswort Stinking shumac. See Tree of Heaven Stone plant family, 383 Strangleweed. See Japanese Dodder Strawberry Guava, 279, 576–79 impacts, 678, 682, 684, 686 ISSG 100 worst invaders, 711 noxious designation, 693 pathways of introduction, 674, 676 Streptopelia decaocto. See Eurasian Collared-Dove Streptopelia risoria. See Ringed Turtle-Dove Strophocaulos arvensis. See Field Bindweed Sturnus vulgaris. See European Starling Sudangrass, 470, 655 noxious designation, 667 Sudden Oak Death, xix (v. 1), 25–29 state-by-state occurrences, 296, 306 Sugarcane aphids, biological control (plants) kikuyugrass, 481 Sulfometuron, chemical control (plants) Japanese honeysuckle, 617 Japanese hops, 621 Sumac family, 544 Summer cypress. See burning bush Sun sensitivity in humans and livestock common St. Johnswort, 360 giant hogweed, 375 Sun spurge. See madwoman’s milk Sunflower family, 344, 399, 417, 427 Surfactant, herbicides, xx (v. 2) Surinam cherry, 659 and strawberry guava, 578 Sus scrofa. See Feral Pig Susumber. See turkey berry Swallow-worts, 636–40 impacts, 678, 680, 684 noxious designation, 666, 668, 669, 671, 693 pathways of introduction, 674 Swamp beaver. See Nutria Swamp dodder. See common dodder Swamp fly-honeysuckle, 505, 658 Swamp rose, 524, 658 Swamp verbena, 414, 652 Sweetberry honeysuckles, 505, 658 Sweet breath of spring. See winter honeysuckle Sweetbriar rose, 524, 658

Sweet cicely, 370, 653 Sweet gale family, 554 Swine, plants toxic to, 360 Swine brucellosis, Wild Pig as carrier, 280 Synchytrium puerariae, biological control (plants) kudzu, 625 Systemic herbicides, xx (v. 2) Taeniatherum asperum. See Medusahead Taeniatherum caput-medusae. See Medusahead Taeniatherum crinitum. See Medusahead Tahiti, 591, 592 Tall wheatgrass, 487, 655 Tall whitetop. See Perennial Pepperweed Tamaricaceae. See tamarisk family Tamarisk, 579–85 impacts, 682, 684, 686 ISSG 100 worst invaders, 711 noxious designation, 666, 668, 669, 670, 671, 672, 693 pathways of introduction, 674, 676 Tamarix chinensis. See Five-stamen Tamarisk and Chinese Tamarisk Tamarix gallica. See French Tamarisk Tamarix parviflora. See Small-flowered Tamarisk Tamarix ramossissima. See Pink-flowered Tamarisk Tamarix species. See Tamarisk Tampico soda apple. See wetlands nightshade Tanglehead. See pili grass Taosa species, biological control (plants) waterhyacinth, 342 Tatarian honeysuckle, noxious designation, 666, 668, 669, 671, 692 and Japanese honeysuckle, 614. See also Exotic Bush Honeysuckles Tebuthiuron, chemical control (plants) buffelgrass, 439 Japanese honeysuckle, 617 Tectococcus ovatus, biological control (plants) strawberry guava, 578 Teleonemia scrupulosa, biological control (plants) lantana, 521 Teline monspessulanus. See Brooms Tender fountain grass. See Crimson Fountain Grass Teredo navalis. See Naval Shipworm Terellia ruficauda, biological control (plants) Canada thistle, 348 Tetralopha scortealis. See lespedeza webworm Tetranychus lintearis, biological control (plants) gorse, 511 Tetranychus urticae, Japanese honeysuckle as host, 617

760 n INDEX Texas umbrella chinaberry, 552, 659 Texas umbrella tree. See Texas umbrella chinaberry Thai eggplant. See turkey berry Thatch bromegrass. See Cheatgrass Theodore Roosevelt National Park, and feral horses, 271, 272, 273 Theory of Island Biogeography, The (MacArthur and Wilson), xxxi (v. 1) Thorny olive. See silverthorn Three-cornered alfalfa leaf hopper, biological control (plants) Chinese lespedeza, 353 Three-leaf akebia, 594, 661 Thrypticus species, biological control (plants) waterhyacinth, 342 Tick quackgrass, 487, 655 Tilapia, ISSG 100 worst invaders, 711 waterhyacinth control, 342. See also Spotted Tilapia Tilapia mariae. See Spotted Tilapia Tilapia zilli. See Redbelly tilapia Tilling, physical control (plants) cheatgrass, 442 cogongrass, 446 dyer’s woad, 365 field bindweed, 609 medusahead, 484 musk thistle, 403 quackgrass, 488 Timandra convectaria, biological control (plants) mile-a-minute, 629 Timandra griseata, biological control (plants) mile-a-minute, 629 Tingis ampliata, biological control (plants) Canada thistle, 349 Tinker’s penny, 359, 653 Tipton weed. See Common St. Johnswort Tithymalus esula. See Leafy Spurge Toadflax, 421–26 impacts, 678, 679, 680, 683, 686 noxious designation, 665, 666, 667, 668, 669, 670, 671, 672, 690 pathways of introduction, 674, 675 Tobacco budworm, 664 Japanese honeysuckle as host, 617 tropical soda apple as host, 533–34 Tobacco hornworm, 664 tropical soda apple as host, 533–34 Tobacco leaf curl, biological control (plants) Japanese honeysuckle, 617 Tobacco mild green mosaic tobamovirus, biological control (plants) tropical soda apple, 534

Toe toe, 475, 655 Tomato hornworm, 664 tropical soda apple as host, 533–34 Tomato pinworm, 664 tropical soda apple as host, 533–34 Tomato spotted wilt, field bindweed as host, 609 Tomato weed. See silverleaf nightshade Toothed spurge, 396, 653 Toothworts, 370, 371, 650, 653 Tordon, chemical control (plants) gorse, 511 Torrey’s nightshade. See western horsenettle Toxicodendron altissima. See Tree of Heaven Toxic plants brooms, 500 buffelgrass, 438 chinaberry, 553 common St. Johnswort, 360 English ivy, 605 field bindweed, 609 giant hogweed, 375 halogeton, 382 Johnsongrass, 472 kikuyugrass, 480 Koster’s curse, 517 lantana, 521 leafy spurge, 397–98 Oriental bittersweet, 632 rattlebox, 529 toadflax, 425 tropical soda apple, 531 yellow starthistle, 430 Trabutina mannipara, biological control (plants) tamarisk, 585 Trapa bicornis. See devil’s pod Trapa bispinosa. See Water Chestnut Trapaceae. See water caltrop family Trapa natans. See Water Chestnut Trapa natans var. bispinosa. See Water Chestnut Trapa natans var. natans. See Water Chestnut Trapdoor snail. See Chinese Mystery Snail Trap-neuter-release (TNR) programs, feral cats, 268 Tree of Heaven, 248, 585–89 impacts, 684 noxious designation, 666, 668, 669, 671, 693 pathways of introduction, 674 uses of, 588 Trees, 540–93 American species invasive abroad, 695 ISSG 100 worst invaders, 710–11 noxious designation, 692–93 Trichapion latrivetre. See sesbania flower beetle

INDEX n 761 Trichomonas gallinae parasite, Eurasian Collared-Dove as host, 236 Trichosirocalus horridus, biological control (plants) musk thistle, 403 Trichosporium visiculosum, biological control (plants) Australian pine, 543 Triclopyr, chemical control (plants) Asiatic colubrina, 495 Australian pine, 543 Brazilian peppertree, 547 brooms, 501 carrotwood, 550 chinaberry, 554 Chinese lespedeza, 352 chocolate vine, 596 common mullein, 36 English ivy, 605 Eurasian watermilfoil, 324 exotic bush honeysuckles, 506 giant hogweed, 375 gorse, 511 Japanese barberry, 514 Japanese knotweed, 390 Koster’s curse, 518 kudzu, 625 multiflora rose, 525 musk thistle, 403 Oriental bittersweet, 632 paper mulberry, 564 porcelainberry, 635 prickly Russian thistle, 413 princess tree, 568 purple loosestrife, 417 rattlebox, 529 strawberry guava, 578 swallow-worts, 640 tamarisk, 585 tree of heaven, 588 tropical soda apple, 534 velvet tree, 592 winter creeper, 643 wisteria, 647 yellow Himalayan raspberry, 538, 539 Triploid grass carp, 174 Triticum repens. See Quackgrass Triticum vaillantianum. See Quackgrass Trompetilla. See West Indian Marsh Grass Tropical curlygrass fern, 600, 653 Tropical Soda Apple, 530–35 impacts, 678, 680, 681, 684, 685 noxious designation, 665, 666, 668, 669, 670, 671, 692 pathways of introduction, 677

Trumpet creeper, 645, 661 Trumpet grass. See West Indian Marsh Grass Tubenose goby, 188 Tuckeroo tree. See Carrotwood Tucson Mountain Park, 438 Tumbleweed. See Prickly Russian Thistle Tunicates, 39–45 Turkey berry, 531, 658 noxious designation, 665, 666, 667, 668, 669, 670, 671, 692 Turkeyfish, 175 Turtles, and Australian pine, 543 Tu Si Zi. See Japanese Dodder Twig girdler, biological control (plants) Australian pine, 543 Twinberry honeysuckle. See bearberry honeysuckle Twitchgrass. See Quackgrass 2,4-D, chemical control (plants) common St. Johnswort, 361 dyer’s woad, 365 Eurasian watermilfoil, 324 field bindweed, 609 gorse, 511 Japanese honeysuckle, 617 leafy spurge, 398 multiflora rose, 525 musk thistle, 403 prickly Russian thistle, 413 spotted knapweed, 420 strawberry guava, 578 tamarisk, 584 velvet tree, 592 water chestnut, 338 waterhyacinth, 342 Twoleaf toothwort. See crinkleroot Two-spotted leafhopper, biological control (plants) fire tree, 557 Tyta luctuosa, biological control (plants) field bindweed, 609 Ugena microphylla. See Old World Climbing Fern Ulex europaeus. See Gorse Umbrellatree. See Chinaberry Unaspis euonumi, biological control (plants) winter creeper, 643 Unintentional pathways of introduction, xxvt (v. 1), 676–77 Upland frog. See African Clawed Frog Urophora species, biological control (plants) spotted knapweed, 421 yellow starthistle, 431 Uruguayan pampas grass. See Pampas Grass

762 n INDEX U.S. Department of Agriculture Soil Conservation Service, xvi (v. 2), xviii (v. 2), 437, 499, 524, 623 Ustilagao bulleta, biological control (plants) cheatgrass, 443 Vaccinium flase bottom, field bindweed as host, 609 Vanessa cardui. See painted butterfly Varanus niloticus. See Nile Monitor Varanus salvator. See Asian water monitor Variable leaf waterhyacinth, 339–40, 649 Variable watermilfoil, 322, 649 noxious designation, 666, 667, 668, 671, 689 Varnish tree. See Tree of Heaven Varroa destuctor. See Varroa Mite Varroa Mite, xix (v. 1), 102–5 Africanized Honey Bee as host, 103, 108 state-by-state occurrences, 295–310 Veined Rapa Whelk, 79–82 state-by-state occurrences, 308 Velvet dock. See Common Mullein Velvet Tree, 515, 589–93 impacts, 682, 684 and Koster’s curse, 515 noxious designation, 667, 693 pathways of introduction, 674 Verbascum thapsus. See Common Mullein Verbenaceae. See verbena family Verbena family, 518 Vertebrates, 157–294 American species invasive abroad, 697 amphibians, 201–14 birds, 228–59 fish, 157–201 ISSG 100 worst invaders, 711–12 mammals, 259–94 reptiles, 214–28 Verticillium dahliae, biological control (plants) tree of heaven, 589 Vincetoxicum medium. See Pale Swallow-Wort Vincetoxicum nigrum. See Black Swallow-Wort Vincetoxicum rossicum. See Pale Swallow-Wort Vines, 594–644 ISSG 100 worst invaders, 710–11 noxious designation, 693 Violets, 370, 653 Violet tunicate, 39 Virginia creeper, 619, 661 Virginia cutgrass, 467, 656 Virginia rose, 524, 658 Virile crayfish, 93, 94 Vitaceae. See grape family

Vitis brevipedunculata. See Porcelainberry Viviparus georgianus, 59 VOC. See volatile organic compound Volatile organic compound, and kudzu, 624 Wahiawa Botanical Garden, and velvet tree, 590 Waiawi. See Strawberry Guava Walking Catfish, xviii (v. 1), 198–201 ISSG 100 worst invaders, 200, 711 state-by-state occurrences, 297 Wall louse. See Common Bed Bug Wasps, biological control (plants) Australian pine, 543 Brazilian peppertree, 548 multiflora rose, 526 velvet tree, 592 Water caltrop. See Water Chestnut Water caltrop family, 335 Water Chestnut, 335–39 impacts, 682, 685 noxious designation, 665, 666, 667, 668, 669, 670, 671, 689 pathways of introduction, 674, 677 Water clover, 327, 330, 650 Water fern. See Giant Salvinia Waterhyacinth, xviii (v. 1), 173, 293, 336, 339–43, 522 impacts, 680, 681, 682, 685 ISSG 100 worst invasives, 710 noxious designation, 665, 666, 668, 669, 670, 671, 689 pathways of introduction, 674, 677 Waterhyacinth moth, biological control (plants) waterhyacinth, 342 Water milfoil family, 322 Water spangles. See common salvinia Water straw grass. See West Indian Marsh Grass Water thyme. See Hydrilla Water velvet. See Giant Salvinia Wauke. See Paper Mulberry Wavyleaf thistle, 345, 653 Weevils, biological control (plants) Australian pine, 543 brooms, 501 Canada thistle, 348, 349 common mullein, 357 Eurasian watermilfoil, 324, 325 garlic mustard, 372 giant salvinia, 330 gorse, 511 kudzu, 625 mile-a-minute, 628–29 musk thistle, 403 purple loosestrife, 417

INDEX n 763 rattlebox, 529 tropical soda apple, 534 spotted knapweed, 421 toadflax, 426 tropical soda apple, 534 velvet tree, 592 water chestnut, 338 waterhyacinth, 342 yellow starthistle, 430–31 West African pennisetum. See Kikuyugrass Western horsenettle, 533, 653 noxious designation, 666, 691 Western morning glory, 607, 661 Western mosquito fish. See Mosquitofish Western wheatgrass, 442, 487, 656 West Indian mahogany, 495, 659 West Indian Marsh Grass, 489–92 impacts 682, 683 noxious designation, 692 pathways of introduction, 675, 677 West Indian raspberry, 537, 658 noxious designation, 692 West Nile Virus, xix (v. 1), 7–10 mosquito as vector, 119 state-by-state occurrences, 295–310 West Virginia white butterfly, and garlic mustard, 371 Wetlands nightshade, 531–32, 661 noxious designation, 665, 666, 667, 668, 669, 670, 671, 693 Wetlands soda apple. See wetlands nightshade Wharf rat. See Norway Rat Whin. See Gorse Whirling disease parasite, salmonids, 187 Whistling pine. See Australian Pine White amur. See Grass Carp White avens, 370, 653 White basswood, 562, 659 White bottlebrush tree. See Melaleuca White cedar. See Chinaberry White-flowered paulownia, 565–66, 659 White ginger, 391, 392, 393, 394, 653 White grass. See Virginia cutgrass White herring. See Alewife White horsenettle. See silverleaf nightshade White lace bryozoan. See Lacy Crust Bryozoan White leaf rust, biological control (plants) perennial pepperweed, 409 White-lipped python, 220 White mulberry, 562, 659 White Pine Blister Rust, 29–35 state-by-state occurrences, 296–310 White ricefield eel. See Asian Swamp Eel

White-spotted jellyfish. See Australian Spotted Jellyfish White swallow-wort, 637, 661 noxious designation, 671, 693 White-tailed deer, 663 and earthworms, 51 White top. See Hoary Cress White-winged parakeet, 250 Wild blackberry. See Yellow Himalayan Raspberry Wild cane. See Giant Reed Wild cinnamon, 495, 659 Wild coffee. See Asiatic Colubrina Wild cucumber, 619, 661 Wild donkey. See Feral Burro Wild Free-Roaming Horse and Burro Act (1971), 273, 274 Wild ginger. See Kahili Ginger Wild grape, 603, 661. See also Porcelainberry Wild horse. See Feral Horse Wild oats. See Cheatgrass Wild parsnip, 373, 653 Wild pigs. See Feral Pig Wild raspberry. See Yellow Himalayan Raspberry Wild rye, 483, 656. See also Quackgrass Wild snapdragon. See Toadflax Wilelaiki. See Brazilian Peppertree Willow Flycatcher, 662 and giant reeds, 464 Wilson, E. O., xxxi (v. 1) Windwitch. See Prickly Russian Thistle Winter creeper, 640–44 impacts, 684 noxious designation, 693 pathways of introduction, 674 Winter honeysuckle, 504–5, 658 Winter shad. See Gizzard Shad Wiregrass. See Quackgrass Wisteria, 644–47 impacts, 681, 684 noxious designation, 693 pathways of introduction, 674 Wistar Institute, Philadelphia, 289 Wisteria sinensis. See Chinese Wisteria Wisteria floribunda. See Japanese Wisteria Witchgrass. See Quackgrass Witchweed. See Prickly Russian Thistle WNV. See West Nile Virus Wolf’s milk. See Leafy Spurge Wolf’s primrose, 386, 653 Woman’s tongue, 572–73, 660 Woodbine. See Japanese Honeysuckle Woolly. See Hemlock Woolly Adelgid

764 n INDEX Wooly Dutchman’s pipe, 594, 661 and climbing ferns, 600 Wooly mullein. See Common Mullein World Conservation Union (IUCN), ISSG 100 worst invasive alien species, 710–12 Wormwood, 434, 658 Wrinkle wrinkle. See Common Periwinkle Xenopus laevis. See African Clawed Frog Xylella fastidiosa, glassy-winged sharpshooter as vector, 137. See also bacterial leaf scorch Yellow anaconda, 220 Yellow-brown stink bug. See Brown Marmorated Stink Bug Yellow cane. See Common Reed Yellow-chevroned parakeet, 250 Yellow cockspur. See also Yellow Starthistle Yellow eel. See Asian Swamp Eel Yellow fever mosquito, 117 Yellow ginger, 391–92, 393, 394, 653 Yellow Himalayan Raspberry, 535–39 impacts, 684 ISSG 100 worst invaders, 711 noxious designation, 667, 692 pathways of introduction, 676 Yellow honeysuckle, 505, 658 Yellow raspberry. See Yellow Himalayan Raspberry Yellow sage. See Lantana

Yellowspine thistle, 345, 653 Yellow Starthistle, 402, 427–31 impacts, 679, 680, 683, 685, 686 noxious designation, 665, 666, 667, 668, 669, 670, 671, 691 pathways of introduction, 677 Yellow toadflax. See Toadflax Yersinia pestis, carried by black rats’ fleas, 262, 290 Zacate buffel. See Buffelgrass Zapata bladderpod, 438, 653 Zasloff, Dr. Michael, 204 Zauclophora pelodes, biological control (plants) Australian pine, 543 Zebrafish. See Lionfish Zebra Mussel, xix (v. 1), xxiv (v. 1), xxvt (v. 1), xxvii (v. 1), xxviii (v. 1), xxix (v. 1), 58, 76, 77, 78, 79, 80, 82–86, 189, 190 ISSG 100 worst invaders, 711 state-by-state occurrences, 295–10 Zingiberaceae. See ginger family Zonate leafspot, biological control (plants) tree of heaven, 589 Zooids bryozoan young, 36, 37 tunicate young, 39–0, 42 Zosterops japonicas. See Japanese White-Eye Zyginidia guyumi, biological control (plants) giant reed, 466

n About the Authors SUSAN L. WOODWARD received her PhD in Geography—with a specialization in biogeography—from the University of California, Los Angeles in 1976. Her doctoral research included three years along the Lower Colorado River studying feral burros, considered by some then and now to be an invasive species. When her work began, the burro (along with the feral horse) had just been placed under the jurisdiction of the U.S. Bureau of Land Management (BLM), which had a federal mandate to manage this living symbol of the Old West. The results of her field work provided the BLM with some of its earliest baseline data on burro population biology and ecology. Dr. Woodward taught biogeography, physical geography, and human ecology for 22 years at Radford University in Virginia, before retiring in 2006. She is the author of Biomes of Earth (2003) and served as general editor and author of three volumes for Greenwood Guides to Biomes of the World (2009). JOYCE A. QUINN retired from California State University, Fresno as professor emerita after 21 years of teaching a variety of courses in physical geography and mapping techniques. She earned an MA from the University of Colorado and a PhD from Arizona State University, both in Geography, specializing in the effect of climate and soils on the distribution of plants. She has traveled extensively throughout North America, Latin America, Europe, northern and southern Africa, Uzbekistan, Nepal, China, Southeast Asia, Micronesia, and elsewhere. She is a member of the Cactus and Succulent Society of America and the California Invasive Plant Council and is the author of two volumes of Greenwood Guides to Biomes of the World (2009).