General Technical 

Report NRS-52 

Revised October 2017

A Guide to Nonnative Invasive 

Plants Inventoried in the North by 

Forest Inventory and Analysis

Cassandra Olson

Anita F. Cholewa

United States Department of Agriculture

Forest Service

Northern Research 

Station
Visit our homepage at: https://www.nrs.fs.fed.us/

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Published by: For additional copies:

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September 2009 Fax: (740)368-0152

Revised October 2017 Available online at:

http://www.nrs.fs.fed.us/pubs/34183

Manuscript received for publication 3 March 2009

Cover Photos

Front: clockwise from top left: spotted knapweed, photo by Cindy Roche, 

Bugwood.org; European privet, photo by Nava Tabak, Invasive Plant Atlas of New 

England, Bugwood.org; multiflora rose, photo by James H. Miller, U.S. Forest 

Service, www.forestryimages.com; Dame’s rocket, photo used with permission, by 

Kelly Kearns, Wisconsin DNR.

Back: Northern Research Station Forest Inventory and Analysis field crew, 

photos by Cassandra Olson, U.S. Forest Service.
A Guide to Nonnative Invasive 

Plants Inventoried in the North by 

Forest Inventory and Analysis

Cassandra Olson

Ecologist, U.S. Forest Service, 

Northern Research Station

Anita F. Cholewa

Curator, Bell Museum & Planetarium, 

University of Minnesota

Acknowledgments

Special thanks go out to Anita F. Cholewa, Curator at the Bell 

Museum & Planetarium for getting this field guide started in 2004 

and for all her help making revisions in 2007 and 2017. Also 

thanks to Katherine Johnson, Dale Gormanson, David Haugen, 

John Vissage, Keith Moser, James Blehm, Dan Kaisershot, Travis 

Rymal, Cassandra M. Kurtz, and Barb Winters for helping with my 

various requests as this guide was put together.

Plant names and data for individual species distribution were 

taken from the January 2000 version of the NRCS Plants 

Database: https://plants.usda.gov. Other sources for individual 

species distribution are noted in the References section.
Scientific name

Common name NRCS PLANTS Code

Foreword

This field guide is intended to aid Forest Inventory and Analysis 

(FIA) field crews in identifying 43 plants listed in Appendix 9 of 

the FIA National Core Field Guide, Volume 1 Supplement: Field 

Data Collection Procedures for Phase 2+ Plots, Version 7.1 

(https://nrs.fs.fed.us/fia/data-collection/). Species are arranged 

alphabetically by growth form (trees, woody, vines, etc.).

In the updated version of this guide, no new species have been 

added, but you will find new pictures and distribution maps plus 

added descriptive text for some of the plants that will enhance its 

usefulness.

Phragmites australis

Present

Not present

A picture showing infestation

A distribution map taken from NRCS 

PLANTS database and showing the 

Northern Research Station (NRS) region.

Elizabeth J. Czarapata

The first page for each nonnative invasive plant is arranged 

as follows:
Contents

TREE SPECIES

Norway maple Acer platanoides 1

Tree-of-heaven Ailanthus altissima 5

Silktree Albizia julibrissin 9

Russian olive Elaeagnus angustifolia 13

Punktree Melaleuca quinquenervia 17

Melaleuca

Chinaberry Melia azedarach 21

Princesstree Paulownia tomentosa 25

Royal paulownia

Black locust Robinia pseudoacacia 29

Saltcedar Tamarix ramosissima 33

Tamarisk

Tallow tree Triadica sebifera 37

Siberian elm Ulmus pumila 41

WOODY SPECIES

Japanese barberry Berberis thunbergii 45

Common barberry Berberis vulgaris 49

Autumn olive Elaeagnus umbellata 53

Glossy buckthorn Frangula alnus 57

European alder

Alder buckthorn

European privet Ligustrum vulgare 61

Showy fly honeysuckle Lonicera ×bella 65

Amur honeysuckle Lonicera maackii 69

Morrow’s honeysuckle Lonicera morrowii 73

Tatarian honeysuckle Lonicera tatarica 77

Common buckthorn Rhamnus cathartica 81

Multiflora rose Rosa multiflora 85

Japanese meadowsweet Spiraea japonica 89

European cranberrybush Viburnum opulus 93

Snowball bush

VINE SPECIES

Asian bittersweet Celastrus orbiculatus 97

Black swallow-wort Cynanchum louiseae 101

Louise’s swallow-wort
European swallow-wort Cynanchum rossicum 105

Pale swallow-wort

English ivy Hedera helix 109

Japanese honeysuckle Lonicera japonica 113

HERBACEOUS SPECIES

Garlic mustard Alliaria petiolata 117

Spotted knapweed Centaurea biebersteinii 121

Canada thistle Cirsium arvense 125

Bull thistle Cirsium vulgare 129

Leafy spurge Euphorbia esula 133

Dame’s rocket Hesperis matronalis 137

Creeping jenny Lysimachia nummularia 141

moneywort

Purple loosestrife Lythrum salicaria 145

Japanese knotweed Polygonum cuspidatum 149

Mexican bamboo

Giant knotweed Polygonum sachalinense 153

Bohemian knotweed Polygonum ×bohemicum 157

GRASS SPECIES

Nepalese browntop Microstegium vimineum 161

Japanese stiltgrass

Reed canarygrass Phalaris arundinacea 165

Common reed Phragmites australis 169

Phragmites

REFERENCES 173

APPENDIX 1: Leaf and Inflorescence Morphology 175

APPENDIX 2: Comparison pf Nonnative Shrubby Lonicera 182

APPENDIX 3: Key to the Species Lonicera 183

APPENDIX 4: Comparison of Nonnative Berberis Species 184

APPENDIX 5: Key to the Species Berberis 185

APPENDIX 6: Notes About the Polygonum (Fallopia) Species 186

APPENDIX 7: Key to the Species Elaeagnus 187

GLOSSARY 189
TREES 1

Acer platanoides

Norway maple ACPL

Infestation.

Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
2 TREES

Acer platanoides

Norway maple ACPL

Form: Deciduous tree 40-80 ft (12-25 m) tall.

Leaves: Opposite leaves palmately lobed with 5-7 lobes; the 

margins have a few large teeth. Buds large, over 1⁄4 inch (0.6 

cm), green or reddish, and blunt.

Flowers/fruit: Yellowish-green flowers in rounded clusters 

give way to large samara fruit.

Habitat: Vacant lots, successional forests, upland fields, and 

hedgerows.

Other distinguishing features/notes: Broken leafstalk of 

Norway maple yields milky juice (sugar maple yields clear 

juice). Also, wings of the samara on Norway maple diverge 

at almost 180 degrees (sugar maple diverges at a narrower 

angle, about 120 degrees). Winter: resembles sycamore 

maple, but edges of opposing leaf scars meet on Norway 

maple twigs.

Notes
TREES 3

Acer platanoides

Norway maple

Samara.

Paul Wray, Iowa State University, 

Bugwood.org

Bark.

Paul Wray, Iowa State University, 

Bugwood.org

Buds.

Paul Wray, Iowa State University, 

Bugwood.org

Samara.

Bill Cook Michigan State University, 

Bugwood.org

Flowers.

Bill Cook Michigan State University, 

Bugwood.org
4 TREES

Twig.

Paul Wray, Iowa State University, 

Bugwood.org

Leaves.

Bill Cook Michigan State University, 

Bugwood.org

Acer platanoides

Norway maple
TREES 5

Ailanthus altissima

Tree-of-heaven AIAL

Infestation.

Chris Evans, University of Georgia, Bugwood.org. Note: Small treeof-heaven plants (center and lower right) growing among the very 

similar looking, and native, winged sumac (top left and top right).
6 TREES

Ailanthus altissima

Tree-of-heaven AIAL

Form: Deciduous tree 80-98 ft (25-30 m) tall. Grows rapidly. 

Twigs hairless, yellow-brown, stout, with yellowish pith.

Leaves: Pinnately compound up to 3 ft (1 m) long; 11- 41 

leaflets not toothed except for a pair of gland-tipped teeth near 

bases. Leaf scars very large, somewhat triangular with many 

bundle scars.

Flowers/fruit: Blooms June-July. Flowers small, yellowish, 

often unisexual in pyramidal cluster; male blossoms emit foul 

odor. Fruits narrow, twisted samaras.

Habitat: Woodlands, urban areas, open fields, steep and 

shallow slopes, and closed canopy forest. Tolerates poor to 

rich soils.

Similar species: Resembles coffeetree (Gymnocladus dioicus), 

which has large compound leaves and leaf scars, but fewer 

bundle scars, twice-compound leaves, and salmon-colored 

pith. Winter: stout twigs, false end buds, large leaf scars, and 

numerous bundle scars distinctive in tree-of-heaven.

Notes
TREES 7

Ailanthus altissima

Tree-of-heaven

Leaves.

Barbara Tokarska-Guzik, University of 

Silesia, Bugwood.org

Leaves and flowers.

Barbara Tokarska-Guzik, University of 

Silesia, Bugwood.org

Leaflets.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Twisted samara.

James H. Miller, U.S. Forest Service, 

Bugwood.org
8 TREES

Large leaf scar.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Sapling.

Chris Evans, University of Georgia, 

Bugwood.org

Bark.

Chris Evans, University of Georgia, 

Bugwood.org

Samaras.

Steve Dewey, Utah State University, 

Bugwood.org

Gland-tipped teeth.

Chris Evans, University of Georgia, 

Bugwood.org

Ailanthus altissima

Tree-of-heaven
TREES 9

Albizia julibrissin

Silktree ALJU

Infestation.

James H. Miller, U.S. Forest Service, 

Bugwood.org
10 TREES

Albizia julibrissin

Silktree ALJU

Form: Soft-wooded, deciduous tree 20- 40 ft (6-12 m) tall. 

Twigs are hairless, slender. Leaf scars small with 3 bundle 

scars. Bark smooth, light brownish in color.

Leaves: Feathery, fern-like, twice-compound leaves. Buds 

few-scaled, small, blunt, not sunk in bark. End buds false. 

Pith whitish.

Flowers/fruit: Flowers June-August. Pink flower clusters 

resemble powder-puffs. Fruits dry, flattened, bean-like 

legumes that are 2-3 inches (5-7.5 cm) long.

Habitat: Dry to wet sites. Spreads along streambanks in 

open conditions, but can also persist in shade.

Similar species: Resembles honeylocust (Gleditsia 

tricanthos), which has only once-compound leaves and 

thorns on the twigs and the trunk. Seedlings resemble 

partridge pea (Chamaecrista fasciculate), an annual plant 

with once-pinnately compound leaves.

Notes
TREES 11

Albizia julibrissin

Silktree

Flowers.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Bark.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Flowers.

Chris Evans, University of Georgia, 

Bugwood.org

Leaves and flowers.

James H. Miller, US Forest Service, 

Bugwood.org

Fruit.

James H. Miller, U.S. Forest Service, 

Bugwood.org
12 TREES

Twice-compound leaves.

© Barry A. Rice, The Nature Conservancy, used with 

permission.

Tree.

© Barry A. Rice, The Nature 

Conservancy, used with permission.

Albizia julibrissin

Silktree
TREES 13

Elaeagnus angustifolia

Russian olive ELAN

Infestation.

Steve Dewey, Utah State University, Bugwood.org
14 TREES

Elaeagnus angustifolia

Russian olive ELAN

Form: Mid-sized, usually thorny shrub or small tree that 

grows to 33 ft (10 m) tall.

Leaves: Alternate, egg or lance-shaped, smooth margined, 

silvery on both surfaces.

Flowers/fruit: Blooms June-July. Highly aromatic, creamy 

yellow flowers. Drupelike fruits in clusters; light green to 

yellow (sometimes tinged with red).

Habitat: Forest openings, open forests, and along forest 

edges; shade intolerant. Thrives in sandy flood plains.

Similar species: Silver thorn or thorny olive (E. pungens) 

is an evergreen with brown scaly twigs (Russian olive has 

silver scaly twigs), fruits reddish silver-scaly. Autumn olive 

(E. umbellata) has leaves that are non-scaly on the upper 

surface in summer; flowers in early summer and has many 

reddish, rounded drupes in fall and early winter.

Notes
TREES 15

Elaeagnus angustifolia

Russian olive

Fruit.

Steve Dewey, Utah State University, 

Bugwood.org

Silvery leaves.

Steve Dewey, Utah State University, 

Bugwood.org

Bark.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Fruit clusters.

James H. Miller, U.S. Forest Service, 

Bugwood.org
16 TREES

Leaves and flowers.

James H. Miller, U.S. Forest Service, Bugwood.org

Leaf.

Chris Evans, University of Georgia, Bugwood.org

Thorns.

James H. Miller, U.S. Forest Service, Bugwood.org

Elaeagnus angustifolia

Russian olive
TREES 17

Melaleuca quinquenervia

Punktree MEQU

Melaleuca

Infestation.

Amy Ferritar, South Florida Water Management District, 

Bugwood.org
18 TREES

Melaleuca quinquenervia

Punktree MEQU

Melaleuca

Form: Evergreen tree up to 108 ft (33 m) tall. Bark whitish 

(inner layers reddish), spongy, peeling, in many layers.

Leaves: Leathery, alternate, simple, grayish green, narrowly 

lance-shaped (or elliptical); up to 4 inches (10 cm) long 

and <1 inch (2 cm) wide. Leaf veins are parallel. Smells of 

camphor when crushed.

Flowers/fruit: Flowers creamy white in bottlebrush-like 

spikes up to 61⁄2 inches (16 cm) long at branch tips. Fruit is a 

round, woody capsule, about 1⁄8 inch (3 mm) wide, with many 

tiny seeds.

Habitat: Prefers seasonally wet sites, but also does well in 

standing water and well-drained uplands.

Notes
TREES 19

Melaleuca quinquenervia

Punktree

Melaleuca

Flower spikes.

Amy Ferritar, South Florida Water 

Management District, Bugwood.org

Bottlebrush-like flower.

Amy Ferritar, South Florida Water 

Management District, Bugwood.org

Alternative leaves.

Amy Ferritar, South Florida Water 

Management District, Bugwood.org

Bark.

David Nance, USDA Agricultural 

Research Service, Bugwood.org
20 TREES

Control operation.

Amy Ferritar, South Florida Water Management District, 

Bugwood.org

Bark.

Amy Ferritar, South Florida Water Management District, 

Bugwood.org

Melaleuca quinquenervia

Punktree

Melaleuca
TREES 21

Melia azedarach

Chinaberry MEAZ

Infestation.

David. J. Moorhead, University of Georgia, Bugwood.org
22 TREES

Melia azedarach

Chinaberry MEAZ

Form: Deciduous tree up to 50 ft (15 m) tall. Much branched 

with multiple boles.

Leaves: Alternately whorled, twice-pinnately compound, 

12-231⁄2 inches (30-60 cm) long. Dark green with lacy 

appearance. Leafstalk lime green with base slightly clasping 

stem. Individual leaflets 1-3 inches (3-7 cm) long, with 

margins entire to coarsely crenate to serrate and wavy.

Flowers/fruit: Flowers March-May. Pinkish-lavender to 

whitish petals, stamens united in dark purple tube. Fragrant. 

Fruit a spherical drupe 1⁄2-3⁄4 inch (1.2-1.8 cm) wide. Light 

green turning yellowish green then yellowish tan. Poisonous 

to humans and livestock.

Habitat: Roadsides, forest margins, and around old homesites.

Similar species: Common elderberry (Sambucus 

canadensis), a spreading-crown shrub with once-pinnately 

compound leaves, margins finely serrate, and green to darkpurple berries in flat-topped cluster.

Notes
TREES 23

Melia azedarach

Chinaberry

Compound leaves.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Flowers.

Chris Evans, University of Georgia, 

Bugwood.org

Branch.

Ted Bodner, Southern Weed Science 

Society, Bugwood.org

Fruit.

Cheryl McCormick-Rote, University of 

Florida, Bugwood.org

Bark.

James H. Miller, U.S. Forest Service, 

Bugwood.org
24 TREES

Resprouts.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Twig.

James H. Miller, U.S. Forest 

Service, Bugwood.org

Seedling.

Chris Evans, University of Georgia, 

Bugwood.org

Large tree.

Chuck Bargeron, University of Georgia, 

Bugwood.org

Melia azedarach

Chinaberry
TREES 25

Paulownia tomentosa

Princesstree PATO2

Royal paulownia

Infestation.

Chris Evans, University of Georgia, Bugwood.org
26 TREES

Paulownia tomentosa

Princesstree PATO2

Royal paulownia

Form: Deciduous tree up to 60 ft (18 m) tall. Bark light to 

dark gray, roughened and becoming slightly fissured. Twigs 

and branches stout, glossy gray brown, and speckled with 

numerous lenticels. No terminal buds.

Leaves: Opposite, heart-shaped and densely hairy on both 

surfaces, 6-13 inches (15-30 cm) long. Petioles rough hairy, 

2-8 inches (5-20 cm) long. Leaves larger on resprouts; 16-20 

inches (40-50 cm) across. Flower buds fuzzy, linear, and 

becoming ovoid in summer and persistent on erect stalks 

over winter.

Flowers/fruit: Blooms before leaves in early spring. 

Fragrant. Flowers large, 2-3 inches (5-7 cm); showy, pale 

violet, flared-tubular corollas; in large erect panicles. Fruits 

terminal clusters of pecan-shaped capsules with pointed tips; 

1-2 inches (2.5-5 cm) long and 1⁄2-1 inch (1.5-2.5 cm) wide. 

Pale green in summer turning tan in winter and eventually 

black, persistent into spring.

Habitat: Around old homes, roadsides, riparian areas, and 

forest margins.

Similar species: Resembles catalpa (Catalpa bignonioides

and C. speciosa), which have leaves with hair only on lower 

surfaces. Flowers are more fringed and fruits are long, 

slender, persistent capsules.

Notes
TREES 27

Paulownia tomentosa

Princesstree

Royal paulownia

Pecan-shaped capsules.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Bark.

Chris Evans, University of Georgia, 

Bugwood.org

Flowers.

James Allison, Georgia Department of 

Natural Resources, Bugwood.org

Seedling.

David J. Moorhead, University of 

Georgia, Bugwood.org

Lenticels on twig.

James H. Miller, U.S. Forest Service, 

Bugwood.org
28 TREES

Flowers.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Heart-shaped leaves.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Open seed capsules.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Flowering tree.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Paulownia tomentosa

Princesstree

Royal paulownia
TREES 29

Robinia pseudoacacia

Black locust ROPS

Infestation.

Elizabeth J. Czarapata, used with permission.
30 TREES

Robinia pseudoacacia

Black locust ROPS

Form: Deciduous tree 65-80 ft (20-25 m) tall. Bark is gray or 

light brown, thick and fibrous, heavily ridged and furrowed 

when older, resembles a woven rope.

Leaves: Alternate, once-compound leaves. Leaflets 6-20, 

egg-shaped, margins entire, 3⁄4-11⁄2 inches (2- 4 cm) long. Older 

twigs with pair of thick spines at leaf base.

Flowers/fruit: Blooms in mid to late spring. Flowers fragrant, 

white, 1 inch (2.5 cm) long and pea-like, borne in long 4-8 

inch (10-20 cm) hanging clusters. Fruit is a flattened legume, 

mottled, light brown, 2- 4 inches (5-10 cm) long; containing 4 to 

8 kidney-shaped, smooth, red-brown seeds; ripening in the fall.

Habitat: Cove forests, open upland slopes, fence rows, 

disturbed ground, and limestone soils.

Other distinguishing features/notes: Sunken, white-hairy 

buds burst through leaf scars in spring. Native to the eastern 

seaboard but widely escaping elsewhere.

Similar species: Prickly ash (Zanthoxylum americanum) is 

smaller, rarely over 20 ft (6 m) tall, and has reddish exposed 

buds, with fewer leaflets (generally not more than 10). Small 

prickles are present along underside of leaf stalk and a pair 

of 1/3 inch prickles present just below leaf axils. Honeylocust 

(Gleditsia tricanthos) has smaller leaflets and branched 

unpaired thorns along the twigs.

Notes
TREES 31

Robinia pseudoacacia

Black locust

Bark.

Elizabeth J. Czarapata, used with 

permission.

Legumes.

Elizabeth J. Czarapata, used with 

permission.

Hanging clusters of flowers.

Elizabeth J. Czarapata, used with 

permission.

Paired spines.

Elizabeth J. Czarapata, used with 

permission.
32 TREES

Leaflets and flowers.

Charles T. Bryson, USDA Agricultural 

Research Service, Bugwood.org

Thick spines.

Wisconsin Department of Natural 

Resources, used with permission.

Robinia pseudoacacia

Black locust
TREES 33

Tamarix ramosissima

Saltcedar TARA

Tamarisk

Infestation.

Steve Dewey, Utah State University, Bugwood.org
34 TREES

Tamarix ramosissima

Saltcedar TARA

Tamarisk

Form: Small tree or shrub 3-20 ft (1-6 m) tall.

Leaves: Small, alternate, scale-like leaves. Sessile with a 

narrow base, < 1⁄4 inch (1.5-3.5 mm) long.

Flowers/fruit: Small flowers pale pink to white; arranged in 

dense spike-like racemes. Fruit is a capsule.

Habitat: Flood plains, salt marshes, and roadsides.

Other distinguishing features/notes: Stems and leaves 

of mature plants secrete salt, which eventually forms a 

crust above and below ground that inhibits other plants. 

Also capable of absorbing up to 200 gallons of water a day, 

lowering ground water levels and drying up springs and 

marshy areas.

Similar species: Superficially resembles Juniperus.

Notes
TREES 35

Tamarix ramosissima

Saltcedar

Tamarisk

Plant.

Steve Dewey, Utah State University, 

Bugwood.org

Shrub in flower.

Steve Dewey, Utah State University, 

Bugwood.org

Plants.

© John M. Randall, The Nature 

Conservancy, used with permission.

Shrub.

© John M. Randall, The Nature 

Conservancy, used with permission.

Flower racemes.

© John M. Randall, The Nature 

Conservancy, used with permission
36 TREES

Shrub.

© John M. Randall, The Nature Conservancy, used 

with permission.

Invasion in flower.

© John M. Randall, The Nature Conservancy, used 

with permission.

Invasion at water’s edge.

© John M. Randall, The Nature Conservancy, used 

with permission.

Tamarix ramosissima

Saltcedar

Tamarisk
TREES 37

Triadica sebifera

Tallow tree TRSE6

Infestation.

Cheryl McCormick-Rote, University of Florida, Bugwood.org
38 TREES

Triadica sebifera

Tallow tree TRSE6

Form: Deciduous tree up to 59 ft (18 m) tall.

Leaves: Alternately whorled, distinctly heart-shaped with 

rounded wide-angled base and a short or long attenuate tip. 

Blades 2-3 inches (5-8 cm) long and 11⁄2-21⁄2 inches (4-6 cm) 

wide. Hairless, lime-green petioles 1-3 inches (2.5 -8 cm).

Flowers/fruit: Slender, drooping spikes about 8 inches 

(20 cm) long of tiny flowers, yellowish-green sepals, but 

no petals. Fruit small terminal clusters of 3-lobed capsules 

(occasionally 4-5 lobed), 1⁄2-3⁄4 inches (1.2-2 cm) across. Dark 

green in summer becoming black and splitting to reveal 3 

wax coated seeds resembling popcorn.

Habitat: Streambanks, riverbanks, and wet areas such 

as ditches as well as upland sites. Thrives in freshwater 

and saline soils. Also shade tolerant, flood tolerant, and 

allelopathic.

Similar species: Cottonwoods (Populus spp.) have wavy 

margined leaves without the long attenuate tips, and flaking 

bark.

Notes
TREES 39

Triadica sebifera

Tallow tree

Heart-shaped leaves.

Chris Evans, University of Georgia, 

Bugwood.org

Bark.

Chris Evans, University of Georgia, 

Bugwood.org

Seeds.

Charles T. Bryson, USDA Agricultural 

Research Service, Bugwood.org

Leaf and flower spike.

Chuck Bargeron, University of Georgia, 

Bugwood.org

Leaves and flower spikes.

Chuck Bargeron, University of Georgia, 

Bugwood.org
40 TREES

Infestation.

Chris Evans, University of Georgia, Bugwood.org

Leaves and fruit.

Cheryl McCormick-Rote, University of Florida, Bugwood.org

Splitting fruit.

James H. Miller, U.S. Forest Service, Bugwood.org

Triadica sebifera

Tallow tree
TREES 41

Ulmus pumila

Siberian elm ULPU

Infestation.

Steve Dewey, Utah State University, Bugwood.org
42 TREES

Ulmus pumila

Siberian elm ULPU

Form: Deciduous tree up to 65 ft (20 m) tall. Bark is 

irregularly furrowed, light grayish brown, often streaked with 

lighter stains.

Leaves: Alternate, simple, singly-serrate, small, < 23⁄4 inches 

(< 7 cm). Older leaves sometimes irregularly and minutely 

doubly-toothed. Nearly an equilateral base, dark green and 

smooth above, paler and smooth below.

Flowers/fruit: Blooms in early spring before leaves. Flowers 

small, pale green clusters. Fruit is a hairless samara, nearly 

round, notched at the top, 1⁄2 inch (1.2 cm) in diameter, initially 

pale green, later turning light brown when ripe in spring.

Habitat: Pastures, roadsides, prairies, and disturbed wooded 

sites.

Other distinguishing features/notes: All the native elms 

have obviously doubly-serrate margins and fruits with some 

hairs, either over the surface or along the margins.

Notes
TREES 43

Ulmus pumila

Siberian elm

Leaves.

Steve Dewey, Utah State University, 

Bugwood.org

Tree.

Patrick Breen, Oregon State University, 

Bugwood.org

Leaves.

Patrick Breen, Oregon State University, 

Bugwood.org

Ripe samaras.

USDA NRCS Archives, Bugwood.org

Leaves.

USDA NRCS Archives, Bugwood.org
44 TREES

Bark.

© John M. Randall, The Nature Conservancy, used 

with permission.

Seedling.

© John M. Randall, The Nature Conservancy, used 

with permission.

Ulmus pumila

Siberian elm
WOODY 45

Berberis thunbergii

Japanese barberry BETH

Infestation.

Kelly Kearns, Wisconsin DNR, used with 

permission.
46 WOODY

Berberis thunbergii

Japanese barberry BETH

Form: Deciduous shrub 11⁄2-61⁄2 ft (0.5-2 m) tall. Branches 

are deeply grooved, brown to purple, often with unbranched 

side (spur) shoots. Spines present on branches. Inner bark 

and wood yellow.

Leaves: Entire (toothed in most other species), mostly 

obovate (tapering to petiole); axillary clusters of leaves often 

present; ranging in color from green to bluish green or green 

to dark reddish purple.

Flowers/fruits: Blooms mid-April to May. Solitary or in small 

clusters of pale yellow flowers (no more than 4). Fruit is a 

berry; bright red and globose; about 1⁄3 inch (1 cm) long; 

often persist through winter.

Habitat: Closed canopy forests, open woodlands, wetlands, 

pastures, meadows, and wastelands.

Notes
WOODY 47

Berberis thunbergii

Japanese barberry

Flower clusters.

Kelly Kearns, Wisconsin DNR, used with 

permission.

Small, yellow flowers.

Elizabeth J. Czarapata, used with 

permission.

Bright red fruit.

Elizabeth J. Czarapata, used with 

permission.

Reddish-purple leaves.

Britt Slattery, 

U.S. Fish and Wildlife Service

Shrub in urban setting.

Cassandra Olson, U.S. Forest Service
48 WOODY

Spines on branch.

© Barry A. Rice, The Nature 

Conservancy, used with permission.

Seedling.

© John M. Randall, The Nature Conservancy, used with 

permission.

Berberis thunbergii

Japanese barberry
WOODY 49

Berberis vulgaris

Common barberry BEVU

Infestation.

Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
50 WOODY

Berberis vulgaris

Common barberry BEVU

Form: Deciduous shrub up to 10 ft (3 m) tall. Branches are 

grooved, gray, and usually have groupings of 3 spines (can 

be as few as one) along them.

Leaves: Alternate or fascicled, 3⁄4-2 inches (2-5 cm) long. 

Dull green, obovate to obovate-oblong with finely serrate 

margins (occasionally the serrations are more prominent).

Flowers/fruits: Bright yellow flowers have unpleasant smell, 

in a pendant raceme 1-21⁄2 inches (3-6 cm) long with 10+ 

flowers. Fruit is oblong, dark red to purplish, 1⁄3 inch (1 cm) 

long, containing 1-3 small, black seed.

Habitat: Open canopy forests and sometimes along roads; 

also very successful in calcareous soils.

Notes
WOODY 51

Berberis vulgaris

Common barberry

Finely serrate leaves.

Leslie J. Mehrhoff, University of 

Connecticut, Bugwood.org

Branch specimens. Top: B. vulgaris; 

Middle: hybrid; Bottom: B. thunbergii.

Leslie J. Mehrhoff, University of 

Connecticut, Bugwood.org

Flowers.

Leslie J. Mehrhoff, University of 

Connecticut, Bugwood.org

Spines along branch.

Leslie J. Mehrhoff, University of 

Connecticut, Bugwood.org
52 WOODY

Stems.

Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Fruit.

Leslie J. Mehrhoff, University of Connecticut, 

Bugwood.org

Berberis vulgaris

Common barberry
WOODY 53

Elaeagnus umbellata

Autumn olive ELUM

Infestation.

Chris Evans, University of Georgia, Bugwood.org
54 WOODY

Elaeagnus umbellata

Autumn olive ELUM

Form: Shrubby tree up to 23 ft (7 m) tall with scattered 

thorny branches.

Leaves: Alternate, elliptic, 2-3 inches (5.5 -7.5 cm) long by 

<2 inches (0.5 -5 cm) wide; margins entire and wavy; bright 

green to gray green above, densely silver scaly beneath or 

sometimes with stellate hairs; petioles short and silvery.

Flowers/fruit: Axillary clusters of 5-10 tubular flowers with 

4 lobes; silvery white to yellow, fragrant. Fruits are drupes, 

<1⁄3 inch (6-8 mm) long; red and finely dotted with silvery to 

silvery-brown scales.

Habitat: Forest openings and open forests.

Similar species: Could be confused with Russian olive

(Elaeagnus angustifolia), which has silver scaly twigs and 

leaves; flowers in early summer with many yellow drupes 

in fall and winter. Autumn olive (E. umbellata) has silver

and brown scaly twigs; flowers in early summer with many 

reddish, rounded drupes in fall and early winter. See Trees

section for more on Russian olive (E. angustifolia).

Notes
WOODY 55

Elaeagnus umbellata

Autumn olive

Shrubby tree.

Chris Evans, University of Georgia, 

Bugwood.org

Leaves - upper and lower surfaces.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Thorny branch.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Tubular flower and silvery scaly leaf.

James H. Miller, U.S. Forest Service, 

Bugwood.org
56 WOODY

Bark.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Foliage.

James Allison, Georgia DNR, 

Bugwood.org

Fruit. 

James Allison, Georgia DNR, 

Bugwood.org

Flowers.

Nancy Loewenstein, Auburn University, 

Bugwood.org

Elaeagnus umbellata

Autumn olive
WOODY 57

Frangula alnus

Glossy buckthorn FRAL4

European alder

Alder buckthorn

Infestation.

Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
58 WOODY

Frangula alnus

Glossy buckthorn FRAL4

European alder

Alder buckthorn

Form: Understory shrub/tree up to 23 ft (7 m) tall; often with 

multiple stems at the base.

Leaves: Alternate, with several pectinate lateral veins; 

margins mostly entire (sometimes with some marginal glands); 

mostly alternate, 1-3 inches (2.5 -7.5 cm) long, usually more 

than half as wide as long. Leaves stay green well into autumn.

Flowers/fruit: Flowers bisexual, unlike most relatives; sepals, 

petals, and stamens in fives; pale yellow. Fruit red to black 

with 2-3 seeds.

Habitat: Wetlands including acidic bogs, calcareous fens, 

and sedge meadows. Also does well in upland habitats. Can 

tolerate full sun to deep shade.

Other distinguishing features/notes: Bark is brown with 

silvery, slightly “corky” lenticels that make it resemble native 

cherries or plums. Cutting a branch will expose yellow 

sapwood and orange heartwood. Similar to Carolina buckthorn 

(Rhamnus caroliniana) except not as tall. R. caroliniana can 

get as tall as 39 ft (12 m).

Winter/early spring identification tip: Buds are naked 

(common buckthorn and alderleaf buckthorn have scaly buds). 

Additionally, common buckthorn has opposite leaves with 

serrate margins. Carolina buckthorn also has naked buds, but 

Carolina buckthorn is taller than glossy buckthorn.

Notes
WOODY 59

Frangula alnus

Glossy buckthorn

European alder

Alder buckthorn

Lateral veins on leaf.

© John M. Randall, The Nature 

Conservancy, used with permission.

Lenticels on bark.

Elizabeth J. Czarapata, used with 

permission.

Fruit.

Elizabeth J. Czarapata, used with 

permission.

Foliage.

Kelly Kearns, Wisconsin DNR, used with 

permission.
60 WOODY

Naked bud.

Elizabeth J. Czarapata, used with 

permission.

Twig.

Rob Routledge, Sault College, Bugwood.org

Frangula alnus

Glossy buckthorn

European alder

Alder buckthorn
WOODY 61

Ligustrum vulgare

European privet LIVU

Infestation.

Elizabeth J. Czarapata, used with permission.
62 WOODY

Ligustrum vulgare

European privet LIVU

Form: Shrub up to 16 ft (5 m) tall. Twigs stiff and minutely 

pubescent, slender-1⁄8 inch (2 mm) thick or less.

Leaves: Dark green, opposite, narrowly elliptical, 1-2 inches 

(2.5-5 cm) long; firm without being tough and leathery.

Flowers/fruit: Small, white flowers in dense panicles; tubular 

with flaring lobes, < 1⁄4 inch (0.5 cm) wide; corolla tube much 

longer than lobes. Fruits small black drupes.

Habitat: Bottomland forests, thickets, and roadsides.

Notes
WOODY 63

Ligustrum vulgare

European privet

Flower panicles.

Nava Tabak, Invasive Plant Atlas of 

New England, Bugwood.org

Fruit.

Kelly Kearns, Wisconsin DNR, used with 

permission.

Twigs with fruit.

Elizabeth J. Czarapata, used with 

permission.

Twigs with flowers.

Elizabeth J. Czarapata, used with 

permission.
64 WOODY

Flower. 

Kelly Kearns, Wisconsin DNR, used with 

permission.

Foliage.

The Dow Gardens Archive, 

bugwood.org

Ligustrum vulgare

European privet
WOODY 65

Lonicera ×bella

Showy fly honeysuckle LOBE

Infestation.

Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
66 WOODY

Lonicera ×bella

Showy fly honeysuckle LOBE

Form: Deciduous, upright, arching-branched shrub up to 20 

ft (6 m) tall. Twigs often pubescent, typically hollow.

Leaves: Opposite, simple, ovate to oblong, margins entire; 

sparsely hairy beneath. Sometimes persistent into winter.

Flowers/fruit: Flowers paired in leaf axils. Pink turning 

yellow with age; exterior surface of corolla usually glabrous; 

on peduncles ~1⁄2 inch (5-15 mm) long. Fruit generally a 

red berry. See appendix 2 for a comparison of nonnative 

species.

Habitat: Open forests, forest edge, pastures, roadsides, and 

fields.

Other distinguishing features/notes: The shrubby native 

forms of Lonicera have white solid pith. The nonnative forms 

have dark, usually hollow pith. In the NRS region, the most 

commonly encountered nonnative species are L. tatarica and 

the hybrid L. ×bella (a hybrid of L. morrowii and L. tatarica). 

Because this is a hybrid, it tends also to be the most variable 

in terms of pubescence and leaf shape.

Notes
WOODY 67

Lonicera ×bella

Showy fly honeysuckle

Foliage.

Leslie J. Mehrhoff, University of 

Connecticut, Bugwood.org

Flowers - color stages.

Leslie J. Mehrhoff, University of 

Connecticut, Bugwood.org

Fruit.

Leslie J. Mehrhoff, University of 

Connecticut, Bugwood.org
68 WOODY

Hollow twig.

Elizabeth J. Czarapata, used with 

permission.

Flowers. 

Leslie J. Mehrhoff, University of 

Connecticut, Bugwood.org

Lonicera ×bella

Showy fly honeysuckle
WOODY 69

Lonicera maackii

Amur honeysuckle LOMA6

Infestation.

James H. Miller, U.S. Forest Service, Bugwood.org
70 WOODY

Lonicera maackii

Amur honeysuckle LOMA6

Form: Deciduous, upright, arching-branched shrub up to 16 

ft (5 m) tall. Twigs densely pubescent and typically hollow.

Leaves: Opposite, petiolate, simple. Petioles tomentose. 

Blades elliptic to ovate to somewhat lanceolate, acuminate, 

entire; up to 31⁄2 inches (~9 cm) long and 11⁄2 inches (~4 cm) 

broad; typically densely pubescent at least along lower veins.

Flowers/fruit: Flowers paired, in leaf axils. White, turning 

yellow with age, outer surface of corolla usually glabrous; 

peduncles less than 1⁄4 inch (5 mm), shorter than petioles. 

Berries dark red. See appendix 2 for a comparison of 

nonnative species.

Habitat: Open forests, forest edge, pastures, roadsides, and 

fields.

Other distinguishing features/notes: Generally speaking, 

the shrubby native forms of Lonicera have white solid pith. 

The nonnative forms have dark, hollow pith. In the NRS 

region, the most commonly encountered nonnative species 

are L. tatarica and the hybrid L. ×bella (a hybrid of L. 

morrowii and L. tatarica).

Notes
WOODY 71

Lonicera maackii

Amur honeysuckle

Bark.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Leaves.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Fruit. 

Chuck Bargeron, University of Georgia, 

Bugwood.org

Foliage.

Warner Park Nature Center Archive, 

Bugwood.org
72 WOODY

Flowers and foliage.

Chris Evans, University of Georgia, 

Bugwood.org

Flowers.

Leslie J. Mehrhoff, University of 

Connecticut, Bugwood.org

Hollow twig.

Elizabeth J. Czarapata, used with permission.

Lonicera maackii

Amur honeysuckle
WOODY 73

Lonicera morrowii

Morrow’s honeysuckle LOMO2

Infestation.

Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
74 WOODY

Lonicera morrowii

Morrow’s honeysuckle LOMO2

Form: Deciduous, upright, arching-branched shrub up to 10 

ft (3 m) tall. Twigs pubescent, typically hollow.

Leaves: Opposite, simple, ovate to elliptical to oval, margins 

entire, apex obtuse to acute; ±densely pubescent over the 

whole undersurface. Sometimes persistent into winter.

Flowers/fruit: Flowers paired in leaf axils; white turning 

yellow with age; on long peduncles, ~1⁄2 inch (5-15 mm), 

outer surface of corolla with scattered hairs. Fruit generally 

a red or yellow berry. See appendix 2 for a comparison of 

nonnative species.

Habitat: Open forests, forest edge, pastures, roadsides, 

fields.

Other distinguishing features/notes: Generally speaking, 

the shrubby native forms of Lonicera have white solid pith. 

The nonnative forms have dark usually hollow pith. In the 

NRS region, the most commonly encountered nonnative 

species are L. tatarica and the hybrid L. ×bella (a hybrid of 

L. morrowii and L. tatarica).

Notes
WOODY 75

Lonicera morrowii

Morrow’s honeysuckle

Flowers and foliage.

Leslie J. Mehrhoff, University of 

Connecticut, Bugwood.org

Fruit.

Stacey Leicht, University of Connecticut, 

Bugwood.org

Plant.

© John M. Randall, The Nature 

Conservancy, used with permission.

Flower.

Chris Evans, University of Georgia, 

Bugwood.org
76 WOODY

Infestation.

© John M. Randall, The Nature 

Conservancy, used with permission.

Fruit.

Courtesy Missouri Botanical Plant Finder, 

used with permission.

Hollow stem.

Elizabeth J. Czarapata, used with 

permission.

Lonicera morrowii

Morrow’s honeysuckle
WOODY 77

Lonicera tatarica

Tatarian honeysuckle LOTA

Infestation.

Patrick Breen, Oregon State University, Bugwood.org
78 WOODY

Lonicera tatarica

Tatarian honeysuckle LOTA

Form: Deciduous, upright, arching-branched shrubs up to 

10 ft (3 m) tall. Twigs glabrous, typically hollow.

Leaves: Opposite, simple, ovate to oblong, margins entire, 

apex acute to obtuse, glabrous except margins, which are 

ciliate; sometimes persistent into winter.

Flowers/fruit: Flowers paired in leaf axils; pink or white, 

usually not fading to yellow; exterior surface of corolla 

glabrous; on peduncles 1⁄2-1 inch (1.5-2.5 cm) long. Fruit 

generally a red (rarely yellow) berry. See appendix 2 for a 

comparison of nonnative species.

Habitat: Open forests, forest edge, pastures, roadsides, and 

fields.

Other distinguishing features/notes: Generally speaking, 

the shrubby native forms of Lonicera have white solid 

pith. The nonnative forms have dark, hollow pith. In the 

NRS region, the most commonly encountered nonnative 

species are L. tatarica and the hybrid L. ×bella (a hybrid of 

L. morrowii and L. tatarica).

Notes
WOODY 79

Lonicera tatarica

Tatarian honeysuckle

Flowers.

Patrick Breen, Oregon State University, 

Bugwood.org

Fruit. 

Chris Evans, University of Georgia, 

Bugwood.org

Flower.

Richard Old, XID Services, Inc., 

Bugwood.org

Hollow twig.

Elizabeth J. Czarapata, used with 

permission.
80 WOODY

Leaves.

Ohio State Weed Lab Archives, used 

with permission.

Bark.

Ohio State Weed Lab Archives, used 

with permission.

Lonicera tatarica

Tatarian honeysuckle
WOODY 81

Rhamnus cathartica

Common buckthorn RHCA3

Infestation.

Steven Katovich, USDA Forest Service, 

Bugwood.org
82 WOODY

Rhamnus cathartica

Common buckthorn RHCA3

Form: Shrub or small tree up to 23 ft (7 m) tall; often with 

multiple stems at the base.

Leaves: Mostly opposite with 2- 4 pairs of lateral veins 

curving toward leaf apex; margins toothed.

Flowers: Unisexual; sepals, petals, and stamens in fours. 

Fruit black with 4 seeds.

Habitat: Forests, savannas, prairies. Thrives on well-drained 

soils.

Other distinguishing features/notes: Thorn-tipped twigs 

and the yellow inner bark are distinctive characteristics of 

common buckthorn. Also, other buckthorns have alternate

leaves, while common buckthorn has opposite leaves and 

twigs are often tipped with a spine.

Similar species: Native alderleaf buckthorn (R. alnifolia)

has scaly buds but alternate leaves with 5-8 paris of veins, 

sepals and stamens in fives, no petals, and black fruit with 3 

seeds.

Notes
WOODY 83

Rhamnus cathartica

Common buckthorn

Bark.

Elizabeth J. Czarapata, used with 

permission.

Foliage.

Leslie J. Mehrhoff, University of 

Connecticut, Bugwood.org

Flowers.

Leslie J. Mehrhoff, University of 

Connecticut, Bugwood.org

Foliage and fruit.

Elizabeth J. Czarapata, used with 

permission.
84 WOODY

Fruit.

Kelly Kearns, Wisconsin DNR, used with 

permission.

Seedlings.

Kelly Kearns, Wisconsin DNR, used with 

permission.

Thorn-tipped twig.

Elizabeth J. Czarapata, used with 

permission.

Seedling.

Elizabeth J. Czarapata, used with 

permission.

Foliage.

Chris Evans, Univesity of Georgia, 

Bugwood.org

Rhamnus cathartica

Common buckthorn
WOODY 85

Rosa multiflora

Multiflora rose ROMU

Infestation.

James H. Miller, U.S. Forest Service, Bugwood.org
86 WOODY

Rosa multiflora

Multiflora rose ROMU

Form: Shrubs with slender, arching or trailing, flowering 

stems up to 10 ft (3 m) long.

Leaves: Leaf stipules conspicuously pectinately toothed 

(deeply fringed) and glandular with 5-11 leaflets.

Flowers/fruits: White, small, ~1⁄2 inch (about 1 cm wide); 

styles united and protruding from the hypanthium (most 

roses have separate styles and only the stigmas are visible 

above the hypanthium); not to be confused with protruding 

stamens. Rose hips, ~1⁄2-3⁄4 inch (0.5 -1.5 cm), ripen to a 

glossy red.

Habitat: Fields, forests, prairies, some wetlands, and 

roadsides.

Other distinguishing features/notes: Most rose species 

in NRS have pink flowers; multiflora rose (R. multiflora) 

is one of just a few species that have white flowers. Also, 

fringed stipules extend about half the length of the leafstalks. 

R. rugosa, the Japanese rose, is also beginning to show 

invasive tendencies in coastal areas and waterways. This 

species has rugose leathery leaves with deeply indented 

veins, purplish-pink flowers, and petals are often doubled.

Notes
WOODY 87

Rosa multiflora

Multiflora rose

Fruit.

Elizabeth J. Czarapata, used with 

permission.

Flowers.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Fringed stipule.

Chris Evans, University of Georgia, 

Bugwood.org

Foliage.

James H. Miller, U.S. Forest Service, 

Bugwood.org
88 WOODY

Stipule - close up.

James H. Miller, U.S. Forest Service, Bugwood.org

Foliage.

Ted Bodner, Southern Weed Science Society, 

Bugwood.org

Rosa multiflora

Multiflora rose
WOODY 89

Spiraea japonica

Japanese meadowsweet SPJA

Infestation.

UConn Plant Database, www.hort.uconn.edu/plants, Bugwood.org
90 WOODY

Spiraea japonica

Japanese meadowsweet SPJA

Form: Perennial, deciduous shrub in rose family. Grows 

4-6 ft (1.2-1.8 m) tall and about the same in width. Naturally 

variable in form; many varieties in the horticultural trade.

Leaves: Alternate, serrate, generally lanceolate to ovate, 

apex acute, 1⁄2-3 inches (1-7.5 cm) long.

Flowers/fruit: Rosy-pink, borne at the tips of branches in 

flat-topped clusters, 2 inches (5 cm) wide. Fruits about 1/8 

inch (2.5 mm) long; small lustrous capsules.

Habitat: Adapted to disturbed areas; tolerates a wide range 

of soil conditions and grows in full sun to partial shade. 

Commonly found along streams and rivers, forest edges, 

roadsides, and in successional fields and power line rightsof-way.

Similar species: Japanese meadowsweet (S. japonica) 

is similar to Virginia meadowsweet (S. virginiana), but has 

gray-hairy twigs and long-pointed, narrow, toothed leaves.

Notes
WOODY 91

Spiraea japonica

Japanese meadowsweet

Flowers.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Leaves.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Stems.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Plant.

James H. Miller, U.S. Forest Service, 

Bugwood.org
92 WOODY

Flowers.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Flower clusters.

The Dow Gardens Archive, Bugwood.org

Fruit.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Spiraea japonica

Japanese meadowsweet
WOODY 93

Viburnum opulus

European cranberrybush VIOP

Snowball bush

Infestation.

The Dow Gardens Archive, Bugwood.org
94 WOODY

Viburnum opulus

European cranberrybush VIOP

Snowball bush

Form: Deciduous shrub 3-16 ft (1-5 m) tall.

Leaves: Opposite, palmately lobed and veined (maplelike); margins with a few coarse teeth; pubescent on abaxial 

surface (at least on veins); petioles with sessile glands that 

are concave and wider than high.

Flowers/fruit: White with narrow to broadly campanulate 

corollas, in large clusters; outer flowers somewhat larger and 

with broadly flaring corollas. Fruit a reddish drupe about 1⁄2 

inch (1 cm) in diameter.

Habitat: Moist to wet soils along lake margins, slopes, or 

open woods; also found in cultivated fields.

Similar species: Cranberry viburnum or highbush-cranberry 

(Viburnum trilobum or V. opulus var. americanum) has 

stalked petiole glands that are rounded and higher than 

wide.

Notes
WOODY 95

Viburnum opulus

European cranberrybush

Snowball bush

Flowers.

The Dow Gardens Archive, Bugwood.org

Fruit.

The Dow Gardens Archive, Bugwood.org

Fruit.

Richard Webb, self-employed 

horticulurist, Bugwood.org

Flowers.

Richard Webb, self-employed 

horticulurist, Bugwood.org
96 WOODY

Flowers.

Iain Harrison, images.swinburne.edu.au/handle/1111.1/193, 

Creative Commons, BY-NC-ND

Viburnum opulus

European cranberrybush

Snowball bush
VINES 97

Celastrus orbiculatus

Asian bittersweet CEOR7

Infestation.

Kelly Kearns, Wisconsin DNR, used with permission.
98 VINES

Celastrus orbiculatus

Asian bittersweet CEOR7

Form: Deciduous twining vine up to 65 ft (20 m) long. Stems 

can measure up to 4 inches (10 cm) in diameter; olive drab 

with many raised, whitish lenticels.

Leaves: Alternate, mostly oval, sometimes slightly tapering 

to petiole, margins with broadly rounded teeth.

Flowers/fruit: Flowers unisexual (and plants dioecious); 

bloom in spring. Fruits 3-valved capsule; seeds with a fleshy 

red aril; has flowers/fruits in small (2 or 3, maybe 4) axillary 

clusters.

Habitat: Thickets, fence rows, meadows, forest openings, 

margins, and roadsides.

Similar species: Similar to American bittersweet (C. 

scandens) except leaves are nearly circular and it has 

numerous flowers in terminal panicles.

Notes
VINES 99

Celastrus orbiculatus

Asian bittersweet

Leaves and fruit.

Kelly Kearns, Wisconsin DNR, used with 

permission.

Infestation.

Kelly Kearns, Wisconsin DNR, used with 

permission.

Oval shaped leaves.

Elizabeth J. Czarapata, used with 

permission.

Twining vine.

James H. Miller, 

U.S. Forest Service, 

Bugwood.org
100 VINES

Leaves.

Leslie J. Mehrhoff, University of 

Connecticut, Bugwood.org

Flower.

Leslie J. Mehrhoff, University of 

Connecticut, Bugwood.org

Fruit.

Leslie J. Mehrhoff, University of 

Connecticut, Bugwood.org

Vine.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Vine.

Chris Evans, Univesity of Georgia, 

Bugwood.org

Celastrus orbiculatus

Asian bittersweet
VINES 101

Cynanchum louiseae

(Syn.: Vincetoxicum nigrum)

Black swallow-wort CYLO11

Louise’s swallow-wort

Infestation.

Kelly Kearns, Wisconsin DNR, used with permission.
102 VINES

Cynanchum louiseae

(Syn.: Vincetoxicum nigrum)

Black swallow-wort CYLO11

Louise’s swallow-wort

Form: Scrambling or climbing vine up to 61⁄2 ft (2 m) long. 

Stems mostly very slender.

Leaves: Opposite, narrowly to broadly ovate; apex longtapering or acute.

Flowers/fruit: Few-flowered clusters axillary to the leaves; 

flowers small, 5-petaled, star-shaped; corolla purple to 

purplish-black. Milkweed-like fruits 11⁄2-3 inches (4-7 cm) long 

and slender, with pubescent seeds.

Habitat: Moist, sunny places including woods.

Other distinguishing features/notes: Also known as 

Vincetoxicum nigrum.

Similar species: European or pale swallow-wort (Cynanchum 

rossicum) has creamy pink to reddish brown flowers. Its 

twining habit and opposite, smooth leaves with somewhat 

shiny or reflective quality distinguish Cynanchum louiseae

from other native and introduced species in the northeastern 

quarter of the United States and adjacent Canada.

Notes
VINES 103

Cynanchum louiseae

(Syn.: Vincetoxicum nigrum)

Black swallow-wort

Louise’s swallow-wort

Leaves.

Kelly Kearns, Wisconsin DNR, used with 

permission. 

Milkweed-like fruit.

Kelly Kearns, Wisconsin DNR, used with 

permission

Leaves and flowers.

Elizabeth J. Czarapata, used with 

permission.
104 VINES

Foliage.

Kelly Kearns, Wisconsin DNR, used with 

permission.

Flowers.

Kelly Kearns, Wisconsin DNR, used with 

permission.

Climbing vine.

Elizabeth J. Czarapata, used with 

permission.

Cynanchum louiseae

(Syn.: Vincetoxicum nigrum)

Black swallow-wort

Louise’s swallow-wort
VINES 105

Cynanchum rossicum

(Syn.: Vincetoxicum hirundinaria)

European swallow-wort CYRO8

Pale swallow-wort

Infestation.

Leslie J. Mehrhoff, University of Connecticut, 

Bugwood.org
106 VINES

Cynanchum rossicum

(Syn.: Vincetoxicum hirundinaria)

European swallow-wort CYRO8

Pale swallow-wort

Form: Perennial, twining, herbaceous vine up to 61⁄2 ft (2 m) 

long.

Leaves: Oval shaped with pointed tips, 3- 4 inches (7-10 cm) 

long by 2-3 inches (5-7 cm) wide, occurring in pairs along 

the stem.

Flowers/fruit: Few-flowered clusters axillary to leaves; 

small, 5-petaled, star shaped, creamy pink to pale maroon; 

about 1⁄4 inch (0.6 cm) across. Milkweed-like fruits are nearly 

identical to black swallow-wort.

Habitat: Roadsides, fields, edges of woods, rocky areas.

Other distinguishing features/notes: Also known as 

Vincetoxicum hirundinaria.

Similar species: Black swallow-wort (Cynanchum louiseae)

has purple to purplish black flowers and does not have 

rhizomes. Honeyvine (Cynanchum leave), a native species, 

has white flowers; leaves have distinct heart-shaped 

bases and do not have shiny surfaces. The twining habit 

and opposite, smooth leaves with their somewhat shiny or 

reflective quality distinguish black swallow-wort from other 

native and introduced species in the northeastern quarter of 

the United States and adjacent Canada.

Notes
VINES 107

Cynanchum rossicum

(Syn.: Vincetoxicum hirundinaria)

European swallow-wort

Pale swallow-wort

Star-shaped flowers.

© John M. Randall, The Nature 

Conservancy, used with permission.

Fruit.

© John M. Randall, The Nature 

Conservancy, used with permission.

Seeds.

Leslie J. Mehrhoff, University of Connecticut, 

Bugwood.org
108 VINES

Infestation.

Leslie J. Mehrhoff, University of 

Connecticut, Bugwood.org

Plants.

Leslie J. Mehrhoff, University of Connecticut, 

Bugwood.org

Cynanchum rossicum

(Syn.: Vincetoxicum hirundinaria)

European swallow-wort

Pale swallow-wort
VINES 109

Hedera helix

English ivy HEHE

Infestation.

David J. Moorhead, University of Georgia, 

Bugwood.org
110 VINES

Hedera helix

English ivy HEHE

Form: Evergreen climbing vine. Stems attach to the bark of 

trees, brickwork, and other surfaces by way of numerous, 

small root-like structures that exude a glue-like substance. 

Older vines are known to reach 12 inches (30 cm) in 

diameter. Young shoots densely covered with stellate hairs.

Leaves: Alternate, dark green, waxy, somewhat leathery. 

Many recognized leaf forms, the most common a 3-lobed 

leaf with a heart-shaped base. Leaves in full sun are often 

unlobed, oval, and have wedge-shaped bases.

Flowers/fruit: Umbrella-like clusters of small, greenish-white 

flowers bloom in the fall. Fruit is black with a fleshy outer 

covering enclosing one to a few hard, stone-like seeds. 

Fruiting occurs in spring.

Habitat: Woodlands, forest edges, fields, hedgerows, 

coastal areas, salt marsh edges, and other upland areas, 

especially where some soil moisture is present. Does not 

grow well in extremely wet conditions and is often associated 

with some form of land disturbance.

Notes
VINES 111

Hedera helix

English ivy

Flower.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Fruit.

James H. Miller, U.S. Forest Service, 

Bugwood.org

3-lobed leaves.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Unlobed leaves.

Chris Evans, University of Georgia, 

Bugwood.org
112 VINES

Vine.

Chuck Bargeron, University of Georgia, 

Bugwood.org

Leaves.

Jan Samanek, State Phytosanitary 

Administration, Czechia, used with 

permission.

Variegated leaves.

Forest and Kim Starr, 

U.S. Geological Survey

Hedera helix

English ivy
VINES 113

Lonicera japonica

Japanese honeysuckle LOJA

Infestation.

Jil Swearingen, USDI National Park Service, Bugwood.org
114 VINES

Lonicera japonica

Japanese honeysuckle LOJA

Form: Trailing or climbing vine up to 80 ft (25 m) long. 

Young stems finely pubescent; older stems reddish-brown 

and the bark sometimes shredding.

Leaves: Opposite, mostly ovate, apex with an abrupt tooth 

or cusp; margins entire, but can be lobed in early spring; 

undersides appear whitish. Semi-evergreen.

Flowers/fruit: Axillary pairs on a bracted stalk. Flowers 

white to pale cream. Corolla tube approximately equals the 

lobes. Blooms in springtime. Fruit a black berry.

Habitat: Disturbed woods, fields, thickets, and forest edges.

Other distinguishing features/notes: This looks similar 

to the native vine Lonicera hirsuta (hairy honeysuckle) 

when not in flower. However hairy honeysuckle has much 

broader leaves and once L. hirsuta begins flowering, it forms 

distinctive connate terminal leaves and has yellow flowers. If 

not in flower yet, check the site condition. L. japonica will be 

found on disturbed sites. If berries are present, L. hirsuta has 

red ones.

Notes
VINES 115

Lonicera japonica

Japanese honeysuckle

Flowers.

Chuck Bargeron, University of Georgia, 

Bugwood.org

Fruit.

Chuck Bargeron, University of Georgia, 

Bugwood.org

Pairs of flowers.

Elizabeth J. Czarapata, used with 

permission.

Flowers.

Chuck Bargeron, University of Georgia, Bugwood.org
116 VINES

Stem - shredding bark.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Spring leaves with wavy margins.

Ted Bodner, Southern Weed Science 

Society, Bugwood.org

Leaves and fall fruit.

Ted Bodner, Southern Weed Science 

Society, Bugwood.org

Trailing vine.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Lonicera japonica

Japanese honeysuckle
HERBACEOUS 117

Alliaria petiolata

Garlic mustard ALPE4

Infestation.

Victoria Nuzzo, Natural Area Consultants, Bugwood.org
118 HERBACEOUS

Alliaria petiolata

Garlic mustard ALPE4

Form: Herbaceous biennial plant 11⁄2 -61⁄2 ft (0.5-2 m) tall; 

glabrous or with a few simple hairs. First-year plants appear 

as a rosette of green leaves close to the ground, which 

remain throughout the winter developing into mature plants 

the following spring.

Leaves: Deltoid or cordate (lower leaves often rounded or 

reniform); margins coarsely toothed.

Flowers/fruit: Flowers white. Fruit a silique (pod), 11⁄2-

21⁄2 inches (4-6 cm) long, 4-angled, narrowly linear with a 

conspicuous midnerve.

Habitat: Moist, shaded soil on river flood plains, forests, 

roadsides, forest edge, along trails, and in forest openings.

Other distinguishing features/notes: Smells of garlic when 

crushed.

Notes
HERBACEOUS 119

Alliaria petiolata

Garlic mustard

First-year plant.

Elizabeth J. Czarapata, used with 

permission.

Second-year plant.

Elizabeth J. Czarapata, used with 

permission.

Flowers.

Elizabeth J. Czarapata, used with 

permission.
120 HERBACEOUS

Fruit.

Chris Evans, University of Georgia, Bugwood.org

Flowers in May.

Jody Shimp, Illinois DNR, Bugwood.org

Infestation.

Steven Katovich, U.S. Forest Service, Bugwood.org

Alliaria petiolata

Garlic mustard
HERBACEOUS 121

Centaurea biebersteinii

(Syn.: Centaurea stoebe subsp. micranthos)

Spotted knapweed CEBI2

Infestation.

Elizabeth J. Czarapata, used with permission.
122 HERBACEOUS

Centaurea biebersteinii

(Syn.: Centaurea stoebe subsp. micranthos)

Spotted knapweed CEBI2

Form: Herbaceous plant 11⁄2 -5 ft (0.5-1.5 m) tall.

Leaves: Pinnatifid with narrow lobes (wormwood-like), 

sparsely pubescent.

Flowers/fruit: Pink-purple flowers in thistle-like heads. 

Heads discoid but marginal flowers enlarged and with 

irregular corollas. Involucral bracts overlapping in several 

layers, upper margins darkly fringed, often pinkish. Fruits 

achenes <1⁄4 inch (2.5-3.5 mm) long, pale brown to blackish.

Habitat: Fields, roadsides, wasteplaces, prairies, oak and 

pine barrens, dunes, and sandy ridges.

Similar species: Other species of invasive Centaurea are 

beginning to be found in forested areas: C. jacea (brownray 

knapweed) and C. xmoncktonii (meadow knapweed).

Online identification resources: http://www.mda.state.

mn.us/plants/pestmanagement/weedcontrol/noxiouslist.aspx

Notes
HERBACEOUS 123

Centaurea biebersteinii

(Syn.: Centaurea stoebe subsp. micranthos)

Spotted knapweed

Pinnatifid leaves.

Elizabeth J. Czarapata, used with 

permission.

Pink-purple flowers.

Elizabeth J. Czarapata, used with 

permission.

Flower.

Kelly Kearns, Wisconsin DNR, used with 

permission.

Thistle-like flower head.

Cindy Roche, Bugwood.org
124 HERBACEOUS

Plants.

Cindy Roche, Bugwood.org

Seeds.

Barry Rice, sarracenia.com, Bugwood.org

Centaurea biebersteinii

(Syn.: Centaurea stoebe subsp. micranthos)

Spotted knapweed
HERBACEOUS 125

Cirsium arvense

Canada thistle CIAR4

Infestation.

UAF Cooperative Extension Archives, University of Alaska - 

Fairbanks, Bugwood.org
126 HERBACEOUS

Cirsium arvense

Canada thistle CIAR4

Form: Dioecious perennial 1- 4 ft (0.3-1.2 m) tall; plant nearly 

glabrous to sparsely hairy. Deep-seated creeping roots.

Leaves: Alternate with a basal rosette, oblong, and 

irregularly lobed with very prickly margins. Green on both 

sides, glabrous to pubescent underneath. Stems ridged and 

hairy.

Flowers/fruit: Purple to occasionally white; heads up to 1⁄2 

inch (1.3 cm) in diameter, discoid, and 1 inch (2.5 cm) or 

less high. Fruit is an achene 1⁄8-1⁄2 inch (2.5- 4 mm) long with 

a feathery pappus attached to the apex (which lets it float 

through the air).

Habitat: Open habitats including prairies, savannas, fields, 

pastures, wet meadows, and open forests.

Notes
HERBACEOUS 127

Cirsium arvense

Canada thistle

Flowers.

Chris Evans, University of Georgia, 

Bugwood.org

Flowers.

Chris Evans, University of Georgia, 

Bugwood.org

Flower.

Chris Evans, University of Georgia, 

Bugwood.org

Prickly leaf margins.

Mary Ellen (Mel) Harte, Bugwood.org
128 HERBACEOUS

White flowers.

Mary Ellen (Mel) Harte, Bugwood.org

Basal rosette.

Ohio State Weed Lab, The Ohio State 

University, Bugwood.org

Foliage.

Mary Ellen (Mel) Harte, Bugwood.org

Plant.

Steve Dewey, Utah State University, 

Bugwood.org

Purple and white flowers.

Steve Dewey, Utah State University, 

Bugwood.org

Cirsium arvense

Canada thistle
HERBACEOUS 129

Cirsium vulgare

Bull thistle CIVU

Infestation.

Eric Coombs, Oregon Department of 

Agriculture, Bugwood.org
130 HERBACEOUS

Cirsium vulgare

Bull thistle CIVU

Form: Biennial herb up to 61⁄2 ft (2 m) tall. Erect and bushy; 

stem stout, often branched, and hairy; conspicuously spiny; 

winged by the decurrent leaf bases.

Leaves: Oblong to lanceolate; green with coarse hairs 

on upper side, grayish-green with woolly gray hairs on 

underside. Long, pointed, yellow spines extend from the 

leaf blade at midrib and at each lobe. Leaf bases extend 

downward on stem forming long prickly wings.

Flowers/fruit: Purple, 1-2 inches (2.5-5 cm) in diameter, 

densely discoid borne singly at the tip of a stem. Fruits are 

achenes, light brown, usually with darker streaks, <1⁄4 inch 

(3- 4.5 mm) long, with a feathery pappus at the apex.

Habitat: Capable of invading fields, pastures, wastelands, 

and along roadsides, but will not survive in cultivated fields. 

Not typically found on sand or soils with high humus content 

and is absent from pure clay soils. Does not grow well in 

shade and drought conditions.

Similar species: Bull thistle differs from Canada thistle, 

(Cirsium arvense), in that leaves are pubescent on both 

sides, while those of Canada thistle are pubescent only on 

the lower side. Flower bracts of bull thistle have spines, in 

contrast to those of Canada thistle, which are merely prickly.

Notes
HERBACEOUS 131

Cirsium vulgare

Bull thistle

Seedling.

Utah State University Archives, 

Bugwood.org

Basal rosette.

Michael Shephard, U.S. Forest Service, 

Bugwood.org

Conspicuous spines.

Steve Dewey, Utah State University, 

Bugwood.org

Coarse hairs.

Steve Dewey, Utah State University, 

Bugwood.org

Flower. Note spiny bract.

Loke T. Kok, Virginia Polytechnic 

Institute and University, Bugwood.org
132 HERBACEOUS

Seed head.

Ohio State Weed Lab Archive, The Ohio State University

Flower.

Forest and Kim Starr, 

U.S. Geological Survey

Cirsium vulgare

Bull thistle
HERBACEOUS 133

Euphorbia esula

(Syn.: Euphorbia virgata)

Leafy spurge EUES

Infestation.

William M. Ciesla, Forest Health 

Management International, Bugwood.org
134 HERBACEOUS

Euphorbia esula

(Syn.: Euphorbia virgata)

Leafy spurge EUES

Form: Herbaceous plant up to 31⁄2 ft (1 m) tall; vigorously 

colonial.

Leaves: Linear to very narrowly elliptical, <1⁄2 inch (<1 cm) 

wide, essentially 1-veined, mostly alternate but those in and 

near the inflorescence opposite or whorled.

Flowers/fruit: Floral bracts (often mistaken for petals) 

broadly oval, greenish-yellow; carpels apparently stalked, but 

actually these are individual flowers.

Habitat: Roadsides and wasteplaces, stream valleys, open 

woodlands, and fields.

Similar species: Resembles butter-and-eggs (Linaria 

vulgaris). Leafy spurge (E. esula) exudes a milky sap when 

leaves or stem are broken while L. vulgaris does not.

Notes
HERBACEOUS 135

Euphorbia esula

(Syn.: Euphorbia virgata)

Leafy spurge

Greenish-yellow flowers.

Elizabeth J. Czarapata, used with 

permission.

Floral bracts.

Elizabeth J. Czarapata, used with 

permission.

Plant.

© John M. Randall, The Nature 

Conservancy, used with permission.
136 HERBACEOUS

Plant.

William M. Ciesla, Forest Health 

Management International, Bugwood.org

Young plant.

Norman E. Rees, USDA Agricultural 

Research Service, Bugwood.org

Euphorbia esula

(Syn.: Euphorbia virgata)

Leafy spurge
HERBACEOUS 137

Hesperis matronalis

Dame’s rocket HEMA3

Infestation.

Elizabeth J. Czarapata, used with permission.
138 HERBACEOUS

Hesperis matronalis

Dame’s rocket HEMA3

Form: Herbaceous biennial or perennial plant 2-3 ft 

(0.6-1 m) tall.

Leaves: Pubescent with both simple (especially on upper 

surface) and branched (especially on lower surfaces) hairs; 

margins dentate.

Flowers/fruit: Purplish, fragrant flowers with 4 sepals, petals 

and stamens. Fruit a silique, 2-5 inches (5-12 cm) long, 

somewhat angular, lumpy from underlying seeds; seeds in 1 

row.

Habitat: Along roads, open woods, and moist bottom lands.

Notes
HERBACEOUS 139

Hesperis matronalis

Dame’s rocket

Rosette leaves.

Elizabeth J. Czarapata, used with 

permission.

Flowers.

Kelly Kearns, Wisconsin DNR, used with 

permission.

Plant.

Kelly Kearns, Wisconsin DNR, used with 

permission.

Flowers.

Elizabeth J. Czarapata, 

used with permission.
140 HERBACEOUS

Foliage.

Mark Frey, The Presidio Trust, 

Bugwood.org

Foliage.

Mark Frey, The Presidio Trust, 

Bugwood.org

Hesperis matronalis

Dame’s rocket
HERBACEOUS 141

Lysimachia nummularia

Creeping jenny LYNU

moneywort

Infestation.

Richard Old, XID Services, Inc., Bugwood.org
142 HERBACEOUS

Lysimachia nummularia

Creeping jenny LYNU

moneywort

Form: Creeping perennial plant 6-24 inches (15-60 cm) long, 

rooting at nodes. Often forms mats.

Leaves: Opposite or whorled, oval, 1⁄2-1 inch (1-2.5 cm) long. 

Glabrous, fleshy, and somewhat cordate at the base.

Flowers/fruit: Flowers May-August. Yellow flowers about 1 

inch (2.5 cm) wide, long stalked, solitary in the axils. Fruit a 

capsule.

Habitat: Streambanks, river bottoms, ditches, and roadsides.

Notes
HERBACEOUS 143

Lysimachia nummularia

Creeping jenny

moneywort

Flowers.

Richard Old, XID Services, Inc., 

Bugwood.org

Leaves.

Richard Old, XID Services, Inc., 

Bugwood.org

Plants.

Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
144 HERBACEOUS

Plants.

© Mandy Tu, The Nature Conservancy, used with permission.

Plants.

© Mandy Tu, The Nature Conservancy, used with permission.

Lysimachia nummularia

Creeping jenny

moneywort

Plants.

Chris Evans, Univesity of Georgia, Bugwood.org
HERBACEOUS 145

Lythrum salicaria

Purple loosestrife LYSA2

Infestation.

Eric Coombs, Oregon Department of Agriculture, Bugwood.org
146 HERBACEOUS

Lythrum salicaria

Purple loosestrife LYSA2

Form: Perennial plant 3-10 ft (1-3 m) tall, numerous 5- or 

6-sided woody, square stems arising from a single rootstock.

Leaves: Opposite or whorled, lance-shaped, sessile, heartshaped or rounded at the base.

Flowers/fruit: Magenta, dense flower spikes. Individual 

flowers have 5-7 petals. Fruit a capsule.

Habitat: Easily reproduces vegetatively. Capable of invading 

many wetland types, including freshwater wet meadows, 

tidal and nontidal marshes, river and stream banks, pond 

edges, reservoirs, and ditches.

Similar species: Winged loosestrife (Lythrum alatum) is 

a rarer plant, usually shorter, 6-24 inches (0.2-0.7 m) tall, 

with alternate leaves (except for the very lowest). Winged 

loosestrife flowers are solitary in the upper axils, while purple 

loosestrife flowers are in dense spikes. The square stems 

will aid in distinguishing purple loosestrife from other plants 

with purple flowers, such as vervain.

Notes
HERBACEOUS 147

Lythrum salicaria

Purple loosestrife

Foliage.

Steve Dewey, Utah State University, 

Bugwood.org

Flowers.

David Cappaert, Bugwood.org

Flowers.

Linda Wilson, University of Idaho, 

Bugwood.org

Infestation.

Britt Slattery, 

U.S. Fish and Wildlife Service
148 HERBACEOUS

Flowers.

© John M. Randall, The Nature Conservancy, 

used with permission.

Seedling.

Ohio State Weed Lab Archive, The Ohio 

State University, used with permission.

Plant.

Richard Old, XID Services, Inc., 

Bugwood.org

Lythrum salicaria

Purple loosestrife
HERBACEOUS 149

Polygonum cuspidatum

(Syn.: Fallopia japonica var. japonica)

Japanese knotweed POCU6

Mexican bamboo

Infestation.

Jack Ranney, University of Tennessee, Bugwood.org
150 HERBACEOUS

Polygonum cuspidatum

(Syn.: Fallopia japonica var. japonica)

Japanese knotweed POCU6

Mexican bamboo

Form: Stout rhizomatous plant up to 10 ft (3 m) tall; stems 

become ridged or lined; solid; profusely branched.

Leaves: Alternate, petiolate ~1⁄2-11⁄2 inches (1- 4 cm long); 

blade 2-6 inches (5-15 cm) long and 3⁄4- 4 inches (2-10 cm) 

wide, broadly ovate, with a rounded apex with abruptlypointed tip and usually truncate (to somewhat tapering) 

base. Lower surface minutely roughened with short <1⁄8 inch 

(<0.1 mm), blunt-tipped hairs along veins.

Flowers/fruit: Often erect branched clusters (panicles) arise 

from leaf axils; flowers bisexual or carpellate (female only) 

and then on separate plants; perianth white or greenishwhite to pinkish. Fruits 3-sided, dark brown achenes.

Habitat: Upland forests and riparian areas as well as 

wasteplaces and roadsides.

Other distinguishing features/notes: Herbaceous 

perennial, but stems often very stout and almost woody. See 

appendix 6 for further information about Polygonum spp.

Notes
HERBACEOUS 151

Polygonum cuspidatum

(Syn.: Fallopia japonica var. japonica)

Japanese knotweed

Mexican bamboo

Leaf - lower surface.

Ben Legler, The Burke Museum of 

Natural History and Culture, used with 

permission.

Young plant.

Elizabeth J. Czarapata, used with 

permission.

Flower panicles.

Leslie J. Mehrhoff, University of 

Connecticut, Bugwood.org

Fruit.

Jil M. Swearingen, USDI National Park 

Service, Bugwood.org
152 HERBACEOUS

Plant.

Ben Legler, The Burke Museum of 

Natural History and Culture, used with 

permission.

Foliage.

Jack Ranney, University of Tennessee, 

Bugwood.org

Polygonum cuspidatum

(Syn.: Fallopia japonica var. japonica)

Japanese knotweed

Mexican bamboo

Fruit.

Jil M. Swearingen, USDI National Park 

Service, Bugwood.org
HERBACEOUS 153

Polygonum sachalinense

(Syn.: Fallopia sachalienensis)

Giant knotweed POSA4

Infestation.

Tom Heutte, U.S. Forest Service, Bugwood.org
154 HERBACEOUS

Polygonum sachalinense

(Syn.: Fallopia sachalienensis)

Giant knotweed POSA4

Form: Stout perennial plant 3-16 ft (1-5 m) tall.

Leaves: Alternate, petiolate, petioles 1⁄2-11⁄2 inches (1- 4 cm) 

long; blade 6-12 inches (15-30 cm) long and 3-10 inches 

(7-25 cm) wide, ovate-oblong, with an obtuse to acute apex 

and cordate base, lower surface with short <1⁄16 inch (0.2-0.6 

mm) pointed, often twisted, hairs along veins. Leaf strongly 

heart-shaped (cordate).

Flowers/fruit: Erect or spreading branched clusters 

(panicles) arise from leaf axils; flowers bisexual or carpellate 

(female only) and then on separate plants; perianth generally 

greenish. Fruits 3-sided, brown achenes.

Habitat: Upland forests and riparian areas as well as 

wasteplaces and roadsides.

Other distinguishing features/notes: Undersides of the 

leaf have longer hairs than Japanese (P. cuspidatum) and 

bohemian knotweed (P. ×bohemicum). See appendix 6 for 

further information about Polygonum spp.

Notes
HERBACEOUS 155

Polygonum sachalinense

(Syn.: Fallopia sachalienensis)

Giant knotweed

Leaf - lower surface.

Ben Legler, The Burke Museum of 

Natural History and Culture, used with 

permission.

Flowers.

Ben Legler, The Burke Museum of 

Natural History and Culture, used with 

permission.

Plant.

Ben Legler, The Burke 

Museum of Natural History and 

Culture, used with permission.

Leaf - lower surface.

Ben Legler, The Burke Museum of 

Natural History and Culture, used with 

permission.
156 HERBACEOUS

Infestation.

Ben Legler, The Burke Museum of Natural History 

and Culture, used with permission.

Large plants.

Tom Heutte, U.S. Forest Service, Bugwood.org

Polygonum sachalinense

(Syn.: Fallopia sachalienensis)

Giant knotweed
HERBACEOUS 157

Polygonum ×bohemicum

(Syn.: Fallopia ×bohemica)

Bohemian knotweed POBO10

Infestation.

Ben Legler, The Burke Museum of Natural History 

and Culture, used with permission.
158 HERBACEOUS

Polygonum ×bohemicum

(Syn.: Fallopia ×bohemica)

Bohemian knotweed POBO10

Form: Stout perennial up to 8 ft (2.5 m) tall. Hybrid of 

Polygonum cuspidatum and P. sachalinense.

Leaves: Similar to parents. Blades ovate, 2-10 inches (5-25 

cm) long and 3⁄4- 4 inches (2-10 cm) wide, with rounded apex 

with abruptly pointed tip and truncate to cordate base; lower 

veins with short <1⁄8 inch (<0.1 mm), pointed hairs.

Flowers/fruit: Clusters of flowers often with fewer branches, 

otherwise similar to Japanese knotweed (P. cuspidatum).

Habitat: Generally found on disturbed sites, wasteplaces, 

and roadsides.

Other distinguishing features/notes: Compare to 

Japanese (P. cuspidatum) and giant knotweed (P. 

sachalinense). Bohemian knotweed has only recently been 

noticed; it is easily mistaken for and more closely resembles 

Japanese knotweed. Fruits partially or fully fertile, but 

reproduction mostly vegetative. See appendix 6 for further 

information about Polygonum spp.

Notes
HERBACEOUS 159

Polygonum ×bohemicum

(Syn.: Fallopia ×bohemica)

Bohemian knotweed

Stem.

Ben Legler, The Burke Museum of 

Natural History and Culture, used with 

permission.

Flowers.

Ben Legler, The Burke Museum of 

Natural History and Culture, used with 

permission.

Leaves.

Ben Legler, The Burke Museum of 

Natural History and Culture, used with 

permission.

Leaf - lower surface.

Ben Legler, The Burke Museum of 

Natural History and Culture, used with 

permission.
160 HERBACEOUS

Flower cluster.

Ben Legler, The Burke Museum of Natural History and 

Culture, used with permission.

Polygonum ×bohemicum

(Syn.: Fallopia ×bohemica)

Bohemian knotweed
GRASSES 161

Microstegium vimineum

Nepalese browntop MIVI

Japanese stiltgrass

Infestation.

Chris Evans, University of Georgia, Bugwood.org
162 GRASSES

Microstegium vimineum

Nepalese browntop MIVI

Japanese stiltgrass

Form: Sprawling annual grass, 1⁄2-3 ft (0.2-1 m) tall.

Leaves: Alternate; narrowly lanceolate 2- 4 inches (5-10 cm) 

long; blades flat and sparsely hairy on both surfaces, as well 

as along the margins, or sometimes glabrous.

Flowers/fruit: Inflorescence a digitate cluster of 2- 4 narrow 

spike-like branches; pubescent; awns usually present on 

at least some lemmas. Spikelets paired (one sessile, one 

pedicellate); lower glume keeled, upper flat.

Habitat: Flood plains, streamsides, forest edge, roadsides, 

swamps, wet fields, and trailsides.

Other distinguishing features/notes: Although annual, the 

sprawling stems easily root from the nodes, forming dense 

colonies. Sometimes confused with Leersia, browntop can 

be distinguished vegetatively by glabrous nodes and hairs 

on the leaf sheaths near the collar.

Notes
GRASSES 163

Microstegium vimineum

Nepalese browntop

Japanese stiltgrass

Digitate inflorescence.

Elizabeth J. Czarapata, used with 

permission.

Plants.

Ted Bodner, Southern Weed Science 

Society, Bugwood.org

Lanceolate leaves.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Stems.

Ted Bodner, Southern Weed Science 

Society, Bugwood.org
164 GRASSES

Dormant winter foliage.

James H. Miller, U.S. Forest Service, 

Bugwood.org

Fall foliage.

Jil M. Swearingen, USDI National Park 

Service, Bugwood.org

Microstegium vimineum

Nepalese browntop

Japanese stiltgrass

Plants.

Elizabeth J. Czarapata, used with 

permission.

Sprawling growth.

Chuck Bargeron, University of Georgia, 

Bugwood.org
GRASSES 165

Phalaris arundinacea

Reed canarygrass PHAR3

Infestation.

Elizabeth J. Czarapata, used with permission.
166 GRASSES

Phalaris arundinacea

Reed canarygrass PHAR3

Form: Moderately tall, erect grass up to 5 ft (1.5 m); 

perennial.

Leaves: Leaves 1⁄4-3⁄4 inch (0.5-2 cm) wide, ligules 

membranous and large up to 1⁄2 inch (10 mm) long; upper 

surface of blades usually scabrous.

Flowers/fruit: Inflorescence often purplish to gray-green; 

spikelets seemingly 1-flowered (actually 2 membranous flaps 

represent sterile florets), glumes compressed and keeled, 

lemmas awnless.

Habitat: Wetland forests, streambanks, lakeshores, 

marshes, along ditches and moist ground.

Other distinguishing features/notes: Native and 

introduced forms are found in North America but are not 

distinguishable.

Notes
GRASSES 167

Phalaris arundinacea

Reed canarygrass

In bloom.

Elizabeth J. Czarapata, used with permission.

Inflorescence - early summer.

Elizabeth J. Czarapata, used with 

permission.

Emergent plants.

Elizabeth J. Czarapata, used with 

permission.

Inflorescence - midsummer.

Elizabeth J. Czarapata, 

used with permission.
168 GRASSES

Plants.

Kelly Kearns, Wisconsin DNR, used with 

permission.

Fall foliage.

Cassandra Olson, U.S. Forest Service

Mike Haddock, Kansas State University, 

used with permission.

This is the ligule on a stalk of reed canarygrass.

“The highly transparent ligule of reed canarygrass is 

helpful on distinguishing it from other species.” Invasive 

Plants of the Upper Midwest. Elizabeth J. Czarapata. 

The University of Wisconsin Press. 2005.

Phalaris arundinacea

Reed canarygrass
GRASSES 169

Phragmites australis

Common reed PHAU7

Phragmites

Infestation.

James H. Miller, U.S. Forest Service, 

Bugwood.org
170 GRASSES

Phragmites australis

Common reed PHAU7

Phragmites

Form: Large grass up to 13 ft (4 m) tall with stout rhizomes; 

stems hollow.

Leaves: Leaves 3⁄4-11⁄2 inches (2- 4 cm) wide, ligules short 

about 1⁄16 inch (1 mm), truncate and fringed.

Flowers/fruit: Inflorescence densely pubescent, often 

purplish when young; glumes unequal, lemmas narrow and 

long-tapering.

Habitat: Wetland forests, swamps, and wet shores.

Other distinguishing features/notes: Both native (subsp. 

americanus) and nonnative (subsp. australis) Phragmites

occur in the United States. It is this nonnative genotype 

that has become invasive. Invasive populations can be 

distinguished from probable native populations by the 

density of the population and the fruiting heads. If it is the 

nonnative genotype, the population will be very dense (could 

be a monoculture) and the fruiting heads are much larger, 

fluffier, and denser. Native populations tend to be sparser 

and intermixed with other plants and the nonnative genotype 

generally holds fruit later into autumn. Online resources to 

aid in identification: http://www.nps.gov/plants/alien/fact/pdf/

phau1-powerpoint.pdf and http://bellatlas.umn.edu/imagelib/

index.php

Notes
GRASSES 171

Phragmites australis

Common reed

Phragmites

Inflorescence.

Elizabeth J. Czarapata, used with 

permission.

Autumn inflorescence.

Elizabeth J. Czarapata, used with 

permission.

Flowers.

James Allison, Georgia DNR,

Bugwood.org

Dormant plant.

James H. Miller, U.S. Forest Service, 

Bugwood.org
172 GRASSES

Large colony.

Elizabeth J. Czarapata, used with 

permission.

Large colony.

Kelly Kearns, Wisconsin DNR, used 

with permission.

Large seed head.

Usage Rights: CC0 1.0 (Public domain)

Rights holder: Bell Museum + Planetarium, 

University of Minnesota

Access Rights: Users are required to adhere 

to Bell Museum policy. Questions should be 

directed to the curator.

Phragmites australis

Common reed

Phragmites
REFERENCES 173

References

Flora of North America Editorial Committee. 1997-2016. 

Flora of North America, north of Mexico. Vols. 3, 5, 6, 

7, 8, 9, 12, 19, 24, 25. New York, NY: Oxford University 

Press.

Gleason, H.A.; Cronquist, A. 1991. Manual of vascular 

plants of northeastern United States and adjacent 

Canada, 2nd ed. Bronx, NY: New York Botanical Garden.

Great Plains Flora Association. 1986. Flora of the Great 

Plains. Lawrence, KS: University Press of Kansas.

Miller, James A. 2003. Nonnative invasive plants of 

southern forests: a field guide for identification and 

control. Revised. Gen. Tech. Rep. SRS-62. Asheville, 

NC: U.S. Department of Agriculture, Forest Service, 

Southern Research Station.

Newcomb, Lawrence. 1977. Newcomb’s wildflower guide.

Boston-New York-London: Little, Brown and Company.

Petrides, George A. 1972. Peterson field guide series: 

trees and shrubs. New York, NY: Houghton Mifflin.

USDA, Natural Resources Conservation Service. 2017. The 

PLANTS database. Greensboro, NC: U.S. Department 

of Agriculture, Natural Resources Conservation Service, 

Plant Data Team. https://plants.usda.gov.
174 REFERENCES

Additional resources for individual species distribution shown 

on maps:

Alliaria petiolata, Cynanchum rossicum in Rhode Island: 

http://www.crmc.ri.gov/invasives/RI_Invasives.pdf

Polygonum cuspidatum and P. sachalinense in North 

Dakota: http://www.agdepartment.com/noxiousweeds/

searchweeds.asp

Alliaria petiolata in South Dakota. Tatina, Robert. 1998. 

Garlic mustard: an addition to the flora of South 

Dakota. Prairie Naturalist. March 30(1): 52.

Polygonum ×bohemicum in New York: http://www.

springerlink.com/content/7680722675q1777u/

Polygonum ×bohemicum in Wisconsin: http://wisplants.uwsp.

edu/scripts/detail.asp?SpCode=POLxBOH

Polygonum ×bohemicum in Minnesota: https://www.

bellmuseum.umn.edu/research/plants/minnesota-flora
APPENDIXES 175

Appendix 1

Leaf and inflorescence morphology

Leaf Morphology

Source: http://en.wikipedia.org/wiki/File:Leaf_morphology_no_title.png
176 APPENDIXES

Descriptive Inflorescence Terms

Shape Name and Description Example

Single

Sometimes, there is only 

one flower on each stem, 

or the flowers are borne so 

far apart that they cannot be 

described as being part of 

the same flowering cluster. 

They are often large flowers, 

so do not need the support 

of other flowers to attract 

pollinators.

The example is Papaver 

orientale.

Spike

A Spike is a group of flowers 

arising from the main stem, 

without individual flower 

stalks (sessile).

The example is Agastache 

foeniculum.

Raceme

A Raceme is a flower spike 

where the flowers have 

stalks of equal length, and 

the tip of the stem continues 

to grow and produce more 

flowers. Flowers open from 

the bottom up.

The example is Linaria 

vulgaris.

Panicle

A Panicle is a branched 

raceme, each branch having 

a smaller raceme of flowers. 

The terminal bud of each 

branch continues to grow, 

producing more side shoots 

and more flowers.

The example is 

Lagerstroemia indica.
APPENDIXES 177

Shape Name and Description Example

Cyme

A Cyme is a group of flowers 

in which the end of each 

growing point produces 

a flower, so new growth 

comes from side shoots and 

the oldest flowers are at the 

top.

The example is Geranium 

pratense.

Verticillaster

A Verticillaster is a whorled 

inflorescence, where the 

flowers are borne in rings 

at intervals up the stem. 

The tip continues to grow, 

producing more whorls. 

This type of inflorescence 

is common in members of 

the Deadnettle/Mint Family 

(Lamiaceae).

The example is Phlomis 

russelliana.

Corymb

A Corymb is a flower cluster 

where all the flowers are at 

the same level, with flower 

stalks of different lengths, 

forming a flat-topped flower 

cluster.

The example is Achillea 

millefolium.

Umbel

An Umbel is a flower head 

in which all the flower stalks 

are of the same length, 

so that the flower head is 

rounded like an umbrella. 

Many bulbs have this type of 

flower head.

The example is Nerine 

bowdenii.
178 APPENDIXES

Shape Name and Description Example

Compound Umbel

A Compound Umbel is an 

umbel where each stalk 

of the umbel produces a 

smaller umbel of flowers. 

This type of inflorescence 

is typical of members of the 

Celery Family (Apiaceae).

The example is Crithmum 

maritimum.

Capitulum

A Capitulum is a flower 

head composed of many 

separate unstalked flowers 

close together. This type of 

inflorescence is typical of the 

Daisy Family (Asteraceae), 

where the outer flowers 

have one conspicuous large 

petal and the central disk 

is formed of flowers with 

smaller petals.

The example is a Senecio

species.

Source: http://theseedsite.co.uk/inflorescences.html
APPENDIXES 179

Descriptive Flower Shapes

Shape Name and Description Example

Campanulate

(Bell-shaped) A flower with 

a wide tube and flared 

lobes (petal tips), typical 

of the Bellflower family 

(Campanulaceae). The 

length of the tube is variable, 

and the open-ness of the 

flower, but campanulate is 

generally shorter and fatter 

than tubular, and more 

closed than stellate.

The example is Campanula 

cochlearifolia.

Funnelform

(Funnel-shaped) A flower 

that widens gradually from 

the base, ending in an open 

or flared shape.

The example is Cyrtanthus 

elatus.

Trumpet-shaped

A flower that starts as a 

narrow tube, but widens into 

a flared mouth, where the 

petals often turn back.

The example is Petunia 

grandiflora.

Salverform

A flower with a long, thin 

tube, that widens suddenly 

into a flat-faced flower.

The example is Plumbago 

auriculata.
180 APPENDIXES

Shape Name and Description Example

Tubular

A flower with a long, thin, 

straight-sided tube formed 

of united petals, often 

separating at the mouth into 

a flared shape.

The example is a Kniphofia

hybrid.

Urceolate

(Urn-shaped) A flower in 

which the petals are fused 

into an almost enclosed 

globe shape, separating at 

the mouth into individual 

flared petals.

The example is Erica 

tetralix.

Bowl-shaped

A flower with a deep 

dish shape, roughly 

hemispherical, with straight 

sides or with a very slight 

flare at the tips. Much the 

same as cup-shaped.

The example is Argemone 

mexicana.

Saucer-shaped

A flower that is almost flat, 

with slightly upturned petal 

tips.

The example is Geranium 

wallichianum.

Stellate

(Star-shaped) A flower with 

many narrow petals arising 

separately from a central 

point.

The example is Sisyrinchium 

bermudianum album.
APPENDIXES 181

Source: http://theseedsite.co.uk/flowershapes.html

Shape Name and Description Example

Cruciform

(Cross-shaped) A flower 

with four petals at right 

angles to one another. 

Typical of members of 

the Cabbage Family 

(Brassicaceae).

The example is an unknown 

tropical species.

Labiate

(Lipped) A flower divided 

into an upper ‘hood’ and a 

lower flat or pouched lip, 

typical of members of the 

Deadnettle/Mint Family 

(Lamiaceae).

The example is Salvia 

texensis.

Papilionaceous

(Pea-shaped) The flower 

shape typical of members of 

the Papilionaceae, having 

a large upper petal called 

the standard, two large side 

petals called wings, and two 

lower petals, often fused 

together, called the keel, 

which encloses the stamens 

and stigma.

The example is Parochetus 

communis.

Ligulate

(Strap-shaped) A flower 

with one large, long, thin 

petal, typical of ray-florets 

of the Aster/Daisy Family 

(Asteraceae). These look 

like single petals but are all 

individual flowers, each one 

capable of producing its own 

seed.

The example is Cosmos 

bipinnatus.
182 APPENDIXES

Appendix 2

Comparison of nonnative shrubby Lonicera

L. maackii L. morrowii L. tatarica L. ×bella

Shrub height to 5 m to 3 m to 3 m to 6 m

Twigs pubescent pubescent glabrous pubescent

Leaf blade shape

elliptic to ovate 

to lanceolate

oval to elliptic 

to ovate ovate to oblong generally ovate

Leaf blade length 3.5-8.5 cm 2.5- 4 cm 3-6 cm 1.8-6 cm

Leaf apex acuminate obtuse to acute acute to obtuse acute

Leaf surface 

(lower)

densely 

pubescent at 

least along 

lower veins

densely 

pubescent glabrous

scattered 

pubescence 

to nearly 

glabrous

Peduncles

2- 4 mm, 

shorter than 

petioles

5-15 mm, 

longer than 

petioles

15-25 mm, 

longer than 

petioles

5-15 mm, 

longer than 

petioles

Corolla color

white, fading to 

yellow

creamy white 

fading to yellow

white to pink, 

not fading to 

yellow

pink (or white) 

fading to 

yellow

Corolla surface 

(exterior)

usually 

glabrous pubescent glabrous

usually 

glabrous

Berry color

dark red to 

blackish deep red

red (occ. 

Yellow) reddish
APPENDIXES 183

Appendix 3

Key to the species Lonicera

1. Woody vines...2

1. Shrubs...4

2. Flowers and fruits sessile; all leaves petiolate...Lonicera japonica

2. Flowers and fruits stalked; upper leaves connate...3

3. Corolla strongly bilabiate, less than 2.7 cm long; all leaves 

connate...Lonicera dioica

3. Corolla scarcely bilabiate, more than 2.7 cm long; some lower 

leaves petiolate...Lonicera sempervirens

4. Flowers and fruits sessile...Lonicera maackii

4. Flowers and fruits stalked...5

5. Flowers appearing before the leaves expand...Lonicera 

fragrantissima

5. Flowers appearing after the leaves expand...6

6. Style glabrous...Lonicera canadensis

6. Style hirsute...7

7. Corolla strongly bilabiate...Lonicera xylosteum

7. Corolla scarcely bilabiate...8

8. Leaves glabrous beneath; peduncles 1.5-2.5 cm...Lonicera 

tatarica

8. Leaves hairy beneath; peduncles 0.5-1.5 cm...Lonicera morrowii

(Note: Lonicera ×bella, the hybrid between L. tatarica and L. 

morrowii, combines characters of both species and is very 

difficult to separate from its parents.)

Definitions:

Sessile - attached directly to the base, without a stalk.

Glabrous - smooth, without hairs or glands.

Bilabiate - two-lipped.

Peduncle - stalk of an inflorescence or of a solitary flower.
184 APPENDIXES

Appendix 4

Comparison of nonnative Berberis species

Comparison of inflorescences of B. vulgaris and B. thunbergii

Character

Berberis 

vulgaris

Berberis 

thunbergii

Branch spines 3 (can be 1) 1 (can have up to 3)

Inflorescence Raceme Sessile umbel

Leaf margin Serrate Entire

Berry consistency Juicy Dry
APPENDIXES 185

Appendix 5

Key to the species Berberis

1. Leaves evergreen...Berberis julianae

1. Leaves deciduous...2

2. Leaf margins spinulose-toothed; leaves 1.5-9 cm; twigs gray; 

thorns often with 2 side branches as long as the center spine; 

flowers racemose...Berberis vulgaris

2. Leaf margins smooth; leaves 1- 4 cm; twigs brown; thorns 

often solitary, or with 2 small side branches; flowers in small 

clusters or solitary...Berberis thunbergii
186 APPENDIXES

Appendix 6

Notes about the Polygonum (Fallopia) species

Japanese knotweed (Polygonum cuspidatum) grows to 10 ft 

(3 m), profusely branched. Hairs along the lower leaf veins are 

short, less than 1/16 inch (<0.1 mm) and blunt tipped. Leaf bases 

usually truncate (to somewhat tapering).

Giant knotweed (Polygonum sachalinense) can grow as tall as 

16 ft (5 m), is more sparingly branched than Japanese knotweed. 

It has hairs along the lower leaf veins that are less than 1⁄16 inch 

(0.2-0.6 mm) long and the leaf bases are always cordate.

Bohemian knotweed (Polygonum ×bohemicum) is a hybrid 

between the preceding two species. Resembles Japanese 

knotweed in stature, growing to 8 ft (2.5 m). Hairs along the 

lower leaf veins are less than 1/16 inch (<0.1 mm) long but 

pointed instead of blunt-tipped. Leaf bases truncate to cordate.

Note about scientific name: The genus was switched to Fallopia. 

However, for FIA purposes, we are still using the genus 

Polygonum because that is the standardized code from the 

NRCS PLANTS database January 2017 version maintained by 

the FIA IM group.
APPENDIXES 187

Appendix 7

Key to the species Elaeagnus

1. Leaves silvery on both sides; twigs often with thorns...2

1. Leaves silvery beneath, soon greenish above; twigs lacking 

thorns...3

2. Branches silvery; fruit yellow...Elaeagnus angustifolia

2. Branches brown; fruit silvery...Elaeagnus commutata

3. Bracts silvery; fruit subglobose to ovoid on stalks 0.8-1.2 cm 

long...Elaeagnus umbellata

3. Bracts brown; fruit ovoid to oblong on stalks 1.2-2.5 cm long...

Elaeagnus multiflora
188
GLOSSARY 189

GLOSSARY

Achene - Type of dry, indehiscent fruit, small and one-seeded, 

lacking any specialized features.

Acute - Sharp-pointed (as to shape, but not necessarily as to 

texture).

Adnate - Grown together, or attached; applied only to unlike parts, 

as stipules adnate to the petiole, or stamens adnate to the corolla.

Allelopathic - Suppression of growth of a plant by a toxin released 

from a nearby plant of the same or other species.

Aril - Specialized, usually fleshy outgrowth from the funiculus 

that covers or is attached to the mature seed; more loosely, any 

appendage or thickening of the seed coat.

Awn - Slender, usually terminal bristle.

Axil - Upper angle formed between the leaf and the stem.

Axillary - Point where the leaf base or leaf petiole meets the stem.

Basal - Situated at the base.

Berry - Fleshy fruit with multiple seeds.

Biennial - Plant that completes its life cycle in 2 years and then 

dies. The first year is often just a basal rosette of leaves and 

flowering stalks appear in the second year.

Bract - Very small or modified leaf, usually growing at the base of 

a flower or flower cluster.

Carpel - Reproductive organ of an angiosperm, which bears the 

ovules.

Calyx - Collective term for all the sepals of a flower.

Ciliate - Fringed with hairs.

Cordate - Shaped like a stylized heart, with the notch at the base.

Corolla - Collective term for all the petals of a flower.

Deciduous - Losing its leaves at the end of the growing season; 

nonevergreen.

Decurrent - With an adnate wing or margin extending down the 

stem or axis below the point of insertion.

Deltoid - Shaped like an equilateral triangle.

Dentate - Spreading, pointed teeth.

Digitate - Arranged like fingers on a hand—cluster at one point.
190 GLOSSARY

Dioecious - Producing male and female flowers on different plants.

Discoid - In the Asteraceae, with all the flowers of a head bisexual 

and fertile, usually also tubular.

Emergent - Rising out of standing water.

Foliaceous - Leaf-like in flatness, color, and texture.

Funiculus - Stalk connecting an ovule or seed with the placenta.

Glabrous - Smooth, without hairs or glands.

Globose - Spherical.

Glume - One of a pair of bracts, found at the base of a grass 

spikelet.

Herbaceous - Non-woody.

Hip - Fruit type of roses in which the hypanthium becomes fleshy 

and surrounds the matured carpels.

Hypanthium - Cup-like base of a flower to which the stamens, 

sepals, and petals are attached.

Indehiscent - Remaining closed at maturity, or not opening along 

regular lines, as in the acorn or coconut.

Inflorescence - Cluster of flowers and their stalks.

Internode - Part of the stem between two successive nodes.

Involucre - Set of bracts beneath dense capitate inflorescences.

Keel - Sharp or conspicuous longitudinal ridge.

Lanceolate - Lance-shaped; broader toward one end (usually the 

base) and tapering to the other.

Leaflet - Division of a compound leaf.

Lemma - Lower bract that, with the palea, encloses the flower in 

grasses.

Lenticel - Raised, often lighter colored, area on the bark.

Ligule - Thin, often membranous appendage found at the junction 

of a grass leaf and its sheath.

Node - Place on a stem where a leaf is (or has been) attached.

Ocrea, ochrea - Sheath around the stem at the base of the leaf, 

derived from stipules, as in many Polygonaceae.

Pappus - Modified perianth forming a crown on an achene.

Palea - Upper bract that, with the lemma, encloses the flower in 

grasses.
GLOSSARY 191

Panicle - Branched flower cluster, usually multibranched.

Pectinate - Arranged like the teeth on a comb.

Pedicel - Stalk of a single flower in an inflorescence.

Perennial - Plant that lives for more than 2 years.

Perianth - All of the sepals and petals (or tepals) of a flower, 

collectively.

Petiole - The stalk of a leaf.

Pinnate - With 2 rows of lateral branches or appendages, or parts 

along an axis, like barbs on a feather.

Pinnatifid - More or less deeply cut in a pinnate fashion.

Reniform - Kidney shaped.

Rhizome - Creeping underground stem.

Rosette - Cluster of basal leaves (often flattened against the 

ground).

Scabrous - Rough to the touch due to the presence of short, stiff 

hairs.

Scarious - Thin, dry, membranous, and not green.

Sepal - Member of the outermost set of floral leaves, typically 

green or greenish and leafy in texture.

Sessile - Attached directly to the base, without a stalk.

Silique - Elongate, dry, dehiscent fruit with a septum separating 

the two valves.

Spikelet - Literally, a small spike; in grasses and many sedges, 

one of the ultimate flower clusters, each consisting of 1 to many 

flowers plus their subtending bracts.

Stamen - Pollen-producing structure of a flower; consisting of a 

slender stalk (filament) and a knoblike, pollen-bearing tip (anther).

Stellate - Star-shaped.

Stigma - Pollen-receiving tip of the carpel.

Stipule - Small leaflike growth at the base of a leaf stalk.

Style - Stalklike structure, connecting the ovary and the stigma of 

a carpel.

Tomentose - Covered with tangled or matted, woolly hairs.

Trigonous - With 3 angles (applied to solid bodies)

Truncate - With the apex (or base) transversely straight or nearly 

so, as if cut off.
Page intentionally left blank
Olson Cassandra; Cholewa, Anita F. 2009. Revised October 2017. A guide 

to nonnative invasive plants inventoried in the north by Forest 

Inventory and Analysis. Gen. Tech. Rep. NRS-52. Newtown Square, 

PA: U.S. Department of Agriculture, Forest Service, Northern Research 

Station. 191 p. https://doi.org/10.2737/NRS-GTR-52.

The Forest Inventory and Analysis (FIA) program of the U.S. Forest Service 

is an ongoing endeavor mandated by Congress to determine the extent, 

condition, volume, growth, and depletions of timber on the Nation’s forest 

land. FIA has responded to a growing demand for other information about 

our forests including, but not limited to, soils, vegetation, down woody 

material, and invasive plants. The intent of this guide is to aid FIA field staff 

in identifying 44 invasive plant species in the 24-state Northern Research 

Station region (Maine south to Delaware west to Kansas and north to 

North Dakota). However, this guide can be used by anyone interested in 

learning about these invasive plants. It contains distribution maps, short 

descriptions, space for notes, and numerous pictures of each plant.

KEY WORDS: nonnative, invasive, vegetation monitoring

In accordance with Federal civil rights law and U.S. Department of Agriculture (USDA) civil 

rights regulations and policies, the USDA, its Agencies, offices, and employees, and institutions 

participating in or administering USDA programs are prohibited from discriminating based on 

race, color, national origin, religion, sex, gender identity (including gender expression), sexual 

orientation, disability, age, marital status, family/parental status, income derived from a public 

assistance program, political beliefs, or reprisal or retaliation for prior civil rights activity, in any 

program or activity conducted or funded by USDA (not all bases apply to all programs). Remedies 

and complaint filing deadlines vary by program or incident.

Persons with disabilities who require alternative means of communication for program information 

(e.g., Braille, large print, audiotape, American Sign Language, etc.) should contact the responsible 

Agency or USDA’s TARGET Center at (202) 720-2600 (voice and TTY) or contact USDA through 

the Federal Relay Service at (800) 877-8339. Additionally, program information may be made 

available in languages other than English.

To file a program discrimination complaint, complete the USDA Program Discrimination Complaint 

Form, AD-3027, found online at http://www.ascr.usda.gov/complaint_filing_cust.html and at any 

USDA office or write a letter addressed to USDA and provide in the letter all of the information 

requested in the form. To request a copy of the complaint form, call (866) 632-9992. Submit 

your completed form or letter to USDA by: (1) mail: U.S. Department of Agriculture, Office of the 

Assistant Secretary for Civil Rights, 1400 Independence Avenue, SW, Washington, D.C. 20250-

9410; (2) fax: (202) 690-7442; or (3) email: program.intake@usda.gov.