�Edited by Katherine Howe, Mark Renz, Kelly Kearns, Jennifer Hillmer, & Ellen Jacquart

Invasive Plants of the MidwestA Field Guide to

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Credits: This guide was adapted from “Minnesota invasive non-native terrestrial plants: an identifi-cation guide for natural resource managers” by the Minnesota Department of Natural Resources.

Additional editing was provided by Trish Beckjord, Kim Bogenschutz, Carmen Chapin, Joy Mar-burger, and Deborah Seiler. Range map information was provided by Aron Flickinger (IA), Phyllis Higman (MI), Ellen Jacquart (IN), Kelly Kearns (WI), Debbie Maurer (IL), Melissa Moser (OH), Luke Skinner (MN), Jody Shimp (IL), Tim Smith (MO), and John Walkowiak (IA).

Cover photos: Top row (L to R): cut-leaved teasel, Debbie Maurer; wild parsnip, Paul Rothrock; com-mon buckthorn, Paul Rothrock; common reed, Melissa Moser, Ohio DNAPCenter: black locust, Marcia Moore, Friesner Herbarium; Bottom row (L to R): wild parsnip, Nathan Tucker; dame’s rocket, Brandee Smith; yellow sweetclover, Paul Rothrock; purple loosestrife, Kather-ine Howe; garlic mustard, Chris Evans

Color-coded pages: Colored bars at the tops of pages indicate growth form. Colors are used as fol-lows: orange = tree; green = shrub; red = vine; blue = forb; light blue = aquatic plant; brown = grass.

Legend for range maps:Range maps were compiled by consulting experts in each state who compiled information from state databases and other reports for each species. Colors represent abundance of a species in a given state as follows. Widespread- The species is commonly seen in the majority of counties.

Locally abundant -The species is present or frequently seen in the state but is not in the majority of the counties.

Isolated– The species is not commonly seen but is present in solitary populations.

Not known- Not reported to occur in the state.

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Credits and map legend ........................................�Introduction .............................................................4

Tree-of-heaven, Ailanthus altissima .......................5Garlic mustard, Alliaria petiolata ...........................7Japanese barberry, Berberis thunbergii ...................9Musk thistle, Carduus nutans ...............................��Asian bittersweet, Celastrus orbiculatus ...............��Spotted knapweed, Centaurea stoebe ..................�5Canada thistle, Cirsium arvense ............................�7Common teasel & cut-leaved teasel, Dipsacus fullonum & D. laciniatus .......................�9Autumn & Russian olives, Elaeagnus umbellata & E. angustifolia .................��Leafy spurge, Euphorbia esula .............................��Dame’s rocket, Hesperis matronalis .......................�5Blunt-leaved & common privets, Ligustrum obtusifolium & L. vulgare ..................�7Japanese honeysuckle, Lonicera japonica ............�9Asian bush honeysuckles, Lonicera maackii, L. morrowii, L. tatarica, & L. x bella ....................��Purple loosestrife, Lythrum salicaria ......................��

White & yellow sweetclovers, Melilotus alba & M. officianalis ............................�5 Japanese stiltgrass, Microstegium vimineum ........�7Eurasian watermilfoil, Myriophyllum spicatum ...�9Wild parsnip, Pastinaca sativa ...........................4�Reed canarygrass, Phalaris arundinacea ................4�Common reed, Phragmites australis .......................45Japanese knotweed, Polygonum cuspidatum ........47Common & glossy buckthorns, Rhamnus cathartica & Frangula alnus ...................49Black locust, Robinia pseudoacacia ........................5�Multiflora rose, Rosa multiflora .........................5�Crown vetch, Securigera varia ................................55Narrow-leaved & hybrid cattails, Typha angustifolia & Typha x glauca ...................57

Watch list ..........................................................59-6�References and other resources ....................6�-6�Glossary ............................................................6�-64Photo credits .........................................................65

Table of Contents (alphabetized by botanical name)

4

IntroductionInvasive plants challenge the goals, resources, and morale of the people whose passion or livelihood is the conservation of biological diversity, natural resource management, or environmental protection. Sometimes called “biological pollution,” invasive plants establish and persist without cultivation, and spread into disturbed and undisturbed natural habitats. They can crowd out native plants and animals, threaten rare and endangered species, hybridize with close native plant relatives, and even change the way some ecological systems function.

Forewarned is forearmed. When we know how to identify invasive plants, we learn to appreciate high-quality natural areas and native plant communities. Landowners can minimize the impacts and expense of invasions through early detection and prompt response to new infestations of damaging species. Keep watch for the species listed in this field guide, and report new populations or range expansions to landowners and invasive plant organizations.

This field guide covers 36 species, a handful of the invasive plants in the eight-state region covered here. See the “Watch List” section for other important invasive species in the Midwest. In order to make this guide useful for the general public, we avoid most of the specialized botanical language, but see the glossary for unfamiliar terms. The “Other Resources” section provides a good starting point to learn more.

This field guide does not cover invasive plant control methods, because appropriate treatment is site-, species-, and season-specific. Like individual treatments for complex medical conditions, removal of invasive plant populations is one part of a integrated whole of stewardship. There is no one-size-fits-most prescription for invasive species management, but we know that persistent removal and restora-tion works. Control of invasive plants can be expensive, but neglect is many times more costly.tent removal and restoration works. Control of invasive plants can be expensive, but neglect is many times more costly.

5

Tree-of-heavenAilanthus altissima

5

6

Rapidly-growing tree. Mature trees can be 80’ tall or more. Trunk is �-�’ in diameter. Tree-of-heaven has smooth stems with pale gray bark and light chestnut brown twigs. Leaves and male flowers have a strong, unpleasant odor.

Leaves: Large, alternate, pinnately compound, 1-4’ long. Composed of 11-25 leaflets, which are entire with the exception of one to several glandular teeth near the base.

Flowers: Small, yellow-green, with 5-6 petals, in dense, terminal inflorescences. Dioecious. Bloom in late spring.

Fruits & seeds: Green turning pink to tan, papery, two-winged samaras (dry, winged fruit) in clusters. Develop in late summer to early fall and may remain on the tree through winter. A single plant may produce up to �50,000 seeds annually.

Roots: Aggressive, clonal spread from rhizomes.

Ecological threat:• Tree-of-heaven is a prolific seed producer, grows rapidly, reproduces clonally, and is al-

lelopathic. Once established, it can quickly take over a site and form a very dense stand. • It was planted extensively in urban areas because of its ability to tolerate air pollution, drought, and poor soils. It is often seen growing in vacant lots, alleys, and cracks in sidewalks or parking lots. It is commonly seen in fields, woodland edges, and forest openings, and along roadsides and fencerows. • Seedlings may persist under the forest canopy for many years waiting to exploit increased light availability after a gap is opened, such as after a tree harvest.

Tree-of-heaven Ailanthus altissima

7

Garlic mustardAlliaria petiolata

7

8

Herbaceous biennial with stems �-4’ tall. First-year plants form a basal rosette that remains green through the winter. Second-year plants produce one to several flowering stems.

Leaves: Basal leaves are dark green, heart-shaped, with large teeth. Stem leaves on flower-ing plants are alternate, triangular, with large teeth, and can be �-�” across. Leaves and stems smell like garlic when crushed.

Flowers: Small, white, 4-petaled, and abundant. Bloom throughout the spring.

Fruits & seeds: Up to �,000 seeds produced per plant. Seeds are small, dark brown to black, with ridged coats, and arranged in a single row inside long, slender capsules called siliques. Seeds remain viable in the soil for at least 7 years.

Roots: White, slender taproot, “S”-shaped at the top. Will resprout from the root crown if only the top of the plant is removed.

Ecological threat:• Garlic mustard grows in upland and flood-

plain forests and savannas, as well as disturbed areas such as yards and roadsides. It is some-times found in full sun, though it most often grows in areas with some shade and does not do well in acidic soils. • Native herbaceous cover has been shown to decline at sites invaded by garlic mustard. • Garlic mustard alters habitat suitability for native insects, which may affect food availability for birds, mammals, amphibians, and reptiles. • Garlic mustard exudes antifungal chemicals into the soil that disrupt associations between mycorrhizal fungi and native plants, supressing native plant growth.

Garlic mustard Alliaria petiolata

9

Japanese barberryBerberis thunbergii

9

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Small, round, dense, spiny shrub, typically �-�’ tall, though it may grow up to 6’ tall and 6’ wide. The branches are reddish-brown, deeply grooved, somewhat zig-zag in form, and bear a single sharp spine at each node.

Leaves: Small, alternate, entire, and oval to spatulate. May be green, bluish-green, or dark reddish-purple, depending on the cultivar. Ar-ranged in clusters above single spines.

Flowers: Small, yellow, umbrella-shaped, with 6 petals. Single or in clusters of �-4. Bloom in mid-spring.

Fruit & seeds: Small, bright red, oblong berries. Single or in clusters on narrow stalks. Mature in mid-summer and persist on shrub into winter. Dispersed by birds.

Roots: Spreads vegetatively through horizontal lower branches that root freely when they touch the ground. Roots are yellow inside.

Ecological threat:• Japanese barberry forms dense stands in natu-ral habitats including forests, woodlands, oak

savannas, wetlands, pastures, and meadows. It prefers well-drained soils. • It appears to alter soil pH and nitrate levels, creating conditions that are beneficial for its growth. • White-tailed deer avoid browsing on Japanese barberry, preferring to feed on native plants, which gives barberry a competitive advantage. • Japanese barberry was introduced from Japan around �875. It is commonly planted for ornamental purposes, as well as for wildlife and erosion control. Some cultivars produce fewer seeds than others.

Japanese barberry Berberis thunbergii

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Musk thistle (or nodding thistle)Carduus nutans

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Herbaceous biennial, �-7’ tall, with a multi-branched stem. Plants overwinter as rosettes in the first year and bloom in the second year.

Leaves: Dark green with a light green midrib, alternate, coarsely lobed, with a smooth, waxy surface and a prominent spine at the tip of each lobe. Rosette leaves are large, growing up to 12” long.

Flowers: Nodding, disk-shaped flower heads contain hundreds of tiny individual purple flowers. Bloom from spring through early fall. Flower heads are �-�” wide and droop to a 90° angle from the stem when mature.

Roots: Taproot.

Fruits & seeds: Seeds are yellowish-brown, with a bristly, white pappus. Each plant may produce up to �0,000 seeds. Seeds remain viable in the soil for �0 years or more.

Similar species: Plumeless thistle (Carduus acanthoides), another non-native thistle, looks very similar, especially in the rosette stage, and hybridizes with musk thistle. Flower heads

are one-third the size of musk thistle and erect rather than nodding. Leaves are deeply lobed to feathery with hairy undersides; spiny, tough stems grow �-4’ tall.

Ecological threat:• Musk and plumeless thistles generally colonize disturbed areas and roadsides but can become problematic in native grasslands. • Both species are avoided by grazing animals, giving them a competitive advantage over native plants in grasslands.

Musk thistle (or nodding thistle) Carduus nutans

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Asian bittersweetCelastrus orbiculatus

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�4

Woody, perennial climbing vine. Stems may reach 6” in diameter. Male and female flowers usually borne on separate plants.

Leaves: Alternate, glossy, and round with an abruptly pointing tip and shallow-toothed mar-gins, �-5” long.

Flowers: Small, inconspicuous, 5-petaled, green-ish-yellow flowers in clusters of 3-7 at leaf axils. Most plants dioecious.

Fruits & seeds: Showy, round capsules, clustered in leaf axils. Green in summer, yellow to orange in fall. Split open at maturity to reveal three red-orange, fleshy fruits, each containing one or two seeds. Dispersed by birds and small mammals.

Roots: Spreading underground roots can sprout to form new stems.

Similar species: American bittersweet (Celas-trus scandens; native) has fewer, larger clusters of fruits or flowers, which are terminal rather than at leaf axils. Its leaves are less rounded and nearly twice as long as wide. Hybrids of the two occur, which may make identification difficult.

Ecological threat:• Asian bittersweet grows rapidly and is tolerant of a wide range of habitats. • It infests forests, woodlands, fields, hedge-rows, and coastal areas and can grow in open sites or under a closed forest canopy.• Asian bittersweet may damage trees by gir-dling trunks with its woody stem, shading out the tree’s leaves, or weighing down its crown, making it susceptible to damage from wind or heavy snowfall. • It is widely planted as an ornamental vine, and is sometimes planted accidentally when mis-taken for American bittersweet.

Asian bittersweet Celastrus orbiculata

�5

Spotted knapweedCentaurea stoebe (also known as Centaurea maculosa)

�5

�6

Herbaceous, short-lived perennial, �-4’ tall. Persists as a rosette 1-4 years before bolting. Flowering plants usually have �-6 stems, but may have up to �0.

Leaves: Gray-green, covered in rough hairs, and deeply divided. Rosette leaves grow up to 6” long. Stem leaves alternate, with lower stem leaves resembling rosette leaves, becoming small (�-�” long), entire, and linear higher up the stem.

Flowers: Thistle-like pink to purple flower heads, rarely white. Flower heads have stiff bracts tipped with black, fringed hairs. Bloom mid-summer to early fall.

Fruits & seeds: About �,000 small seeds produced per plant. Wind-dispersed for short distances but carried long distances by humans, livestock, or rodents. Viable in soil for up to 7 years.

Roots: Strong taproot. Some plants also produce a shallow mat of fibrous roots extending from plant for several feet. Some sprouting from lateral roots occurs.

CAUTION: Wear long sleeves and gloves when handling. Spotted knapweed exposure can irritate skin in some people.

Ecological threat:• Spotted knapweed threatens dry areas, includ-ing prairie, oak and pine barrens, dunes, and sandy ridges. It also invades roadsides and disturbed areas.• Its roots exude allelopathic chemicals that inhibit the growth of native plants. • It is not palatable as a forage plant and is avoided by both livestock and native grazers.• Infestations cause increased runoff and sedi-mentation and decreased water-holding capacity in soil.

Spotted knapweed Centaurea stoebe (also known as Centaurea maculosa)

�7

Canada thistleCirsium arvense

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Herbaceous perennial, �-6.5’ tall with upright, grooved stems that branch near top of plant. Native to Eurasia, despite the widely-used com-mon name.

Leaves: Alternate, oblong, irregularly lobed, ta-pering, with spiny, toothed margins, and sessile. Amount of spininess and lobing varies between plants.

Flowers: Numerous, small (0.5-0.75” wide), purple to pink (rarely white) terminal flower heads. Bloom throughout summer. Most plants are dioecious.

Fruits & seeds: Small, light brown with a tan pappus that assists in wind-dispersal. One plant can produce up to 5,000 seeds, and seeds remain viable in the soil for up to �0 years.

Roots: Reproduces clonally by creeping roots that grow laterally in soil, up to �0-��’ per year. Also produces taproots that may grow more than 6’ deep. Readily regenerates from root fragments.

Similar species: Canada thistle is distinguished from all other thistles by (�) creeping lateral

roots; (�) dense clonal growth; and (�) small dioecious flower heads.

Ecological threat:• Canada thistle invades open natural areas such as prairies, savannas, glades, dunes, stream-banks, sedge meadows, and forest openings. It also invades croplands, pastures, forest open-ings, lawns and gardens, roadsides, ditches, and waste sites. • Once it has established it spreads quickly, forming monospecific stands and replacing na-tive plants.

Canada thistle Cirsium arvense

�9

Common teasel Dipsacus fullonum

Cut-leaved teasel Dipsacus laciniatus

�0

Herbaceous, monocarpic (flowers once and dies) perennial. Grows as a basal rosette for at least one year. Forms a prickly, angled flowering stalk, �-6’ tall, typically in second or third year.

Leaves: Opposite, large (up to �.5’ long), oblong, and prickly. Leaves of flowering plants join into cup around stem. Common teasel’s leaves are not lobed. Leaves of cut-leaved teasel are broader and have deep, feathering lobes.

Flowers: Hundreds of small flowers clustered in dense, egg-shaped heads. Stiff, spiny, leaf-like bracts curve up from base of flower head. Com-mon teasel has purple flowers and bracts longer than the flower heads. Cut-leaved teasel has white flowers and bracts shorter than the flower heads. Both species bloom in summer.

Fruits & seeds: Each plant can produce as many as �,000 seeds. Seeds remain viable in the soil for at least � years.

Roots: Deep taproot, up to �’ long and �” in diameter.

Ecological threat:• Teasel grows in open areas, including prairies, savannas, and sedge meadows, as well as road-sides and disturbed areas. It can form extensive monospecific stands. • Teasel is still used in horticultural plantings and dried flower arrangements.• Rapid range expansion of cut-leaved teasel has been observed in several midwestern states.

Dipsacus fullonum Dipsacus laciniatus

Common teasel Dipsacus fullonum (also known as Dipsacus sylvestris)Cut-leaved teasel Dipsacus laciniatus

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Autumn olive Elaeagnus umbellata

Russian olive Elaeagnus angustifolia

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Large shrub or small tree with silvery foliage. Autumn olive grows up to �0’. Russian olive can reach up to �0’ and has thorny branches.

Leaves: Simple and alternate. Autumn olive’s leaves are silver-gray on the underside, lance-shaped or elliptic, with entire, wavy margins. Russian olive’s leaves are silver on both sides, longer, and more lance-shaped.

Flowers: Tube- or bell-shaped, fragrant, and borne in leaf axils. Bloom in late spring. Au-tumn olive flowers are light yellow. Russian ol-ive flowers are yellow inside and silver outside.

Fruits & seeds: Fruits of autumn olive are small, fleshy, egg-shaped, pink to red with silver spots. Russian olive fruits are yellow, dry, and olive-like. Both dispersed by birds.

Roots: Associated with nitrogen-fixing bacteria. Cutting or other damage causes root suckering.

Similar species: Two native buffaloberries, silver (Shepardia argentea) and russet (S. canadensis), have silvery foliage but can be distinguished by

having opposite leaves that are silver on both sides.

Ecological threat:• Autumn olive invades open and forested natu-ral areas, as well as roadsides and agricultural fields. Russian olive is usually found in open areas, including wet areas; it uses water more quickly than native species, and it can dry out riparian areas.• Both species alter nutrient cycling by adding nitrogen to the soil.• Both species have been widely planted for wildlife habitat, mine reclamation, wind breaks, and ornamental uses.

Elaeagnus umbellata Elaeagnus angustifolia

Autumn olive Elaeagnus umbellataRussian olive Elaeagnus angustifolia

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Leafy spurgeEuphorbia esula

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Herbaceous perennial, �-�’ tall, with a deep root system and milky sap in stems, flowers, and leaves. Sap is distasteful to some animals and can cause blistering on their mouths or throats.

Leaves: Simple, alternate, bluish-green, smooth, and hairless, with pointed tips.

Flowers: Small, yellowish-green, and surround-ed by cup-shaped bracts. Flowers are paired, with 7-�0 pairs clustered in umbels at tops of stems. Bloom late spring through mid-summer or occasionally into the fall.

Fruits & seeds: Capsules contain three seeds each and burst when dry, dispersing seeds explosively. Each plant can produce more than �50 seeds. Seeds remain viable in the soil for up to 8 years. Dispersed by wildlife, humans, and water.

Roots: Extensive root system with taproots ex-tending up to �5’ deep and lateral roots spread-ing up to �5’. New sprouts from root buds facilitate spread into undisturbed areas.

Similar species: Cypress spurge (Euphorbia

cyparissias) is another invasive plant similar in appearance, but it grows to �’ with narrower leaves.

Ecological threat: • Leafy spurge spreads rapidly in open areas, in-cluding prairies, savannas, and roadsides. It can quickly create a monospecific stand, excluding native vegetation and reducing habitat value.• It is tolerant of a wide range of habitats, from dry to moist, and sunny to semi-shade. It is most aggressive in areas where soil moisture is limited. • Leafy spurge was introduced accidentally from Europe and Asia as a seed contaminant.

Leafy spurge Euphorbia esula

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Dame’s rocketHesperis matronalis

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Showy, short-lived perennial or biennial, �-4’ tall. First-year leaves form a basal rosette that over-winters. Flowering stalks emerge in spring.

Leaves: Lance-shaped, toothed, alternate, and sessile or with a very short petiole. Decrease in size as they ascend the stem. Fine hairs on leaves and stem.

Flowers: Large, loose, rounded inflorescences of fragrant white, pink, or purple 4-petaled flowers. Bloom late spring through summer. Stamens and style are mostly concealed in flower tube, and like all species in the mustard family, there are 6 stamens, 4 long and � short.

Fruits & seeds: Abundant. Produced in long, narrow siliques up to 5” long that are constricted between seeds and break apart lengthwise at maturity.

Similar species: Fall phlox (Phlox paniculata), a native species, has opposite leaves that are not toothed, and flowers with five petals, not four.

Ecological Threat:• Dame’s rocket usually grows in moist and

mesic woodlands, on woodland edges, along roadsides, and in open areas. • Although not much is known about its effects on natural communities, it appears to compete successfully with native species and can be quite persistent once established.• Dame’s rocket is native to Eurasia and was introduced to North America in the �600s. It is widely distributed in the U.S. and Canada. • Dame’s rocket is found in wildflower seed mixes and is planted as an ornamental; it quickly escapes cultivation because of its prolific seed set.

Dame’s rocket Hesperis matronalis

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Border privet & common privetLigustrum obtusifolium & Ligustrum vulgare

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Perennial shrub or small tree with spreading branches, growing ��-�5’ tall, though it may reach up to �0’. Frequently as wide as it is tall. Trunks usually occur as multiple stems with many long, leafy branches attached at near-right angles. Several species occur, but they are dif-ficult to distinguish.

Leaves: Opposite, elliptic to ovate, with entire margins, leathery, tough, and �-�” long.

Flowers: White, with 4 petals fused into a tube, occurring in dense terminal inflorescences. Very abundant and strongly scented. Bloom in early summer.

Fruits & seeds: Abundant, ovoid, contain-ing �-4 seeds. Ripen in late summer to a dark purple-black and persist into winter. Fruits are poisonous to humans but are food for many birds, which distribute seeds. Mature plants can produce hundreds of fruits.

Similar species: Chinese privet (L. sinense) and Japanese privet (L. japonicum) are similar in ap-pearance. Both are invasive in some parts of the

country but are not common in the Midwest.

Ecological threat:• Privet grows along roadsides, in old fields, and in other disturbed habitats. It also occurs in a variety of undisturbed natural areas, including grasslands, forests, and riparian areas.• An extremely adaptable shrub, it escapes culti-vation to invade adjacent areas, rapidly forming dense thickets that displace many native species. • Privet has been commonly used as an orna-mental shrub or hedgerow since its introduction to the United States in the early �800s.• Once established, it is very difficult to remove.

Ligustrum obtusifolium Ligustrum vulgare

Border privet or blunt-leaved privet Ligustrum obtusifoliumCommon privet or European privet Ligustrum vulgare

�9

Japanese honeysuckleLonicera japonica

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Perennial, semi-evergreen, woody vine. Young stems brown or red and usually pubescent. Older stems woody and hollow, with bark that peels in long strips.

Leaves: Simple, opposite, oblong to oval, �.5-�” long, sometimes lobed, may be covered with fine, soft hairs. Leaves persist on vine until mid-winter.

Flowers: Tubular and very fragrant, with petals fused to form two lips and stamens protruding beyond petals. White to pink, turning yellow with age, and occurring in pairs at leaf axils. Bloom late spring to early summer.

Fruits & seeds: Purple to black berries produced in fall. Dispersed by birds and mammals.

Roots: Produces underground rhizomes and long aboveground stolons that develop roots where nodes contact soil.

Similar species: Native honeysuckle vines have red or orange berries, flowers at tips of stems, and connate leaves (fused to form a single leaf with stem growing through it) below flowers.

Ecological threat:• Japanese honeysuckle invades forests, prairies, fields, and roadsides.• Japanese honeysuckle has an advantage over the native trumpet honeysuckle (Lonicera sem-pervirens), because it is browsed less by deer and resprouts vigorously in response to browsing.• Native plants that provide structural support for Japanese honeysuckle have decreased leaf nitrogen, photosynthesis, and growth.• Shrubs and young trees can be killed by girdling when vines twist tightly around stems and trunks.• Its semi-evergreen nature gives it a longer growing season than most native species.

Japanese honeysuckle Lonicera japonica

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Asian bush honeysucklesLonicera maackii, L. morrowii, L. tatarica, & L. x bella

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Dense, multi-stemmed shrubs, 6-��’ tall. Older stems may have shaggy, peeling bark and are often hollow between the nodes.

Leaves: Opposite, oval or oblong, and entire. Leaves may be hairless to downy and green or blue-green.

Flowers: Fragrant, tubular, and arranged in pairs at leaf axils. Reddish pink or white, turning yel-low with age. Bloom mid- to late spring.

Fruits & seeds: Red, orange or yellow, in pairs at leaf axils, and containing many seeds.

Roots: Fibrous and shallow.

Similar species: Native Lonicera shrubs have shorter, sparser growth forms and white pith in stems. Native Diervilla species have yellow flow-ers and grow in dry or rocky sites. Native spe-cies develop leaves �-� weeks later, drop them earlier in the fall, and often have solid stems.

Ecological threat:• Bush honeysuckles invade a broad range of habitats with varying moisture and light levels,

including forests, fens, bogs, lakeshores, road-sides, pastures, and old fields.• They can rapidly form a dense shrub layer that excludes native understory plants, decreases spe-cies richness, and reduces canopy tree growth. • They alter habitats by decreasing light avail-ability, depleting soil moisture and nutrients, and possibly releasing allelopathic chemicals that inhibit growth of other plants. • Their fruits are rich in carbohydrates but do not offer migrating birds the high-fat, nutrient-rich food sources supplied by native plants that are necessary for long flights. • Asian bush honeysuckles have been widely planted for horticulture and for wildlife habitat.

L. maackii L. morrowii

L. tatarica L. x bella

Asian bush honeysuckles Lonicera maackii, L. morrowii, L. tatarica, & L. x bella

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Purple loosestrifeLythrum salicaria

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Herbaceous perennial, �-7’ tall, with 4-, 5-, or 6-sided, somewhat woody stems. Mature plants have multiple stems (�0-50) originating from a woody crown.

Leaves: Opposite, or occasionally alternate, pairs alternating at 90° angles, �-4” long, sometimes appearing in groups of three, lance-shaped, downy, with entire margins, and sessile.

Flowers: Magenta-colored with 5 or 6 petals, clustered in spikes. Bloom all summer.

Fruits & seeds: Very small and borne in capsules that burst at maturity (mid- to late summer). Produce up to � million seeds per plant per year. Seeds remain viable in soil for up to �0 years.

Roots: Large, woody taproot, with extensive rhizomes forming mats below the soil surface.

Ecological threat:• Purple loosestrife invades many wetlands, including wet meadows, marshes, stream banks, pond or lake edges, and ditches.• Its rapid spread by rhizomes allows it to form dense monospecific stands that exclude native

plants.• Dense stands of purple loosestrife are unsuit-able as cover, food, or nesting or spawning habi-tat for a wide range of native wetland animals including ducks, geese, rails, bitterns, muskrats, fish, frogs, toads, and turtles. Many rare and endangered wetland plants and animals are also at risk.• Purple loosestrife reduces water flow in irriga-tion and drainage ditches.• Supposedly sterile ornamental cultivars are known to produce fertile seeds when able to cross-pollinate with other cultivars or wild populations.

Purple loosestrife Lythrum salicaria

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White sweetclover & yellow sweetcloverMelilotus alba & Melilotus officinalis

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Herbaceous biennials in the legume family. The two species can be distinguished by flower color, stature, and flowering time. Yellow sweet clover is usually shorter and blooms earlier. First-year plants do not bloom. Second-year plants grow �-5’ high and are bush-like.

Leaves: Alternate, with 3 finely-toothed leaflets, and clover-like but longer and thinner than other clovers. The middle leaflet grows on a short but distinct stalk.

Flowers: Five-parted, small, white (M. alba) or yellow (M. officinalis), fragrant, pea-like flowers, clustered in dense racemes (unbranched inflo-rescences with flowers on stalks). Second-year plants bloom late spring through summer.

Fruits & seeds: One or two small seeds with hard seed coats produced per flower, with up to �50,000 seeds per plant. Seeds remain viable in the soil for up to �0 years.

Roots: Strong taproot and extensive lateral roots.

Ecological threat:• Sweet clover degrades native grasslands by excluding native species. It invades prairies, savannas, and dunes and grows abundantly on roadsides and abandoned fields. • Fire stimulates germination of sweet clover seeds and can exacerbate invasions.• Native to Europe and Asia, they were brought to the U.S. in the late �600s and are still used today as forage crops and soil enhancers.

Melilotus alba Melilotus officinalis

White sweetclover Melilotus albaYellow sweetclover Melilotus officinalis

�7

Japanese stiltgrass (or Nepalese browntop)Microstegium vimineum

�7

�8

Annual grass �-�’ (occasionally up to 5’) tall that grows in a branching, sprawling, mat-like man-ner. Stems resemble a narrow, delicate bamboo.

Leaves: Pale green, alternate, narrow, lance-shaped, up to �” long and lightly hairy. Pale, silvery stripe of reflective hairs along midrib of upper leaf surface. Turn yellow to orange in fall.

Flowers: Slender stalks 1-3” long of tiny flowers appear late summer and set seed by early fall.

Fruits & seeds: Each plant produces �00-�,000 seeds. Seeds remain viable in the soil for 5 or more years.

Roots: Spreads during the summer and fall by rooting at stem nodes that touch the ground.

Similar species: The native perennial whitegrass (Leersia virginica) looks similar, but lacks the stripe on the upper leaf surface, flowers earlier, and does not turn orange in fall. Pennsylvania smartweed (Polygonum pensylvanicum; native) and lady’s thumb (Polygonum persicaria; exotic) can form masses of grass-like plants, but their flowers are pink and bead-like.

Ecological threat:• Stiltgrass invades forested wetlands, moist woodlands, old fields and thickets, utility rights-of-way, roadsides, and lawns. It often takes hold along streambanks, ditches, and trails, forming a large seedbank and spreading during floods. • Especially well adapted to low light condi-tions, it thrives in forest understories, spreading rapidly to form extensive patches that displace native species. It has become a dominant under-story species in many eastern and midwestern forests.• Stiltgrass may change soil chemistry to its ben-efit by increasing soil pH and nitrate levels.• White-tailed deer may facilitate its invasion by feeding on native plant species and avoiding stiltgrass.

Japanese stiltgrass (or Nepalese browntop) Microstegium vimineum

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Eurasian watermilfoilMyriophyllum spicatum

�

40

Submersed aquatic perennial with long stems and whorls of submersed, feathery leaves. Stems are slender, smooth, and branch at water surface. Reproduces vegetatively from shoot fragments and stolons creeping along lake bed.

Leaves: Thread-like, pinnately compound, with 9-21 pairs of leaflets, and arranged in whorls of �-5 (usually 4) around stem. Leaves limp when plant is removed from water.

Flowers: Reddish, with either 0 or 4 petals. Arranged in 4-flowered whorls on spikes rising above water surface.

Fruits & seeds: Nut-like fruits split into 4 parts. Seeds germinate poorly under natural conditions and are not the primary means of reproduction.

Roots: Fibrous roots attach to sediments. Roots develop along floating stems and allow stem fragments to take root.

Similar species: Northern watermilfoil (M. sibiri-cum; native) typically has 5 to 9 pairs of leaflets. Coontail (Ceratophyllum demersum; native) is often mistaken for the milfoils, but does not have individual leaflets, and its leaves are toothed.

Ecological threat:• This opportunistic species prefers disturbed lake beds, lakes receiving nitrogen- and phosphorous-rich runoff, and lakes with high alkalinity and high concentrations of dissolved inorganic carbon.• Dense stands disrupt aquatic ecosystems by providing excessive cover and shading out na-tive plants used as food for waterfowl.• It cycles nutrients from sediments to the water column, which may lead to deteriorating water quality and algal blooms.• Eurasian watermilfoil is readily dispersed by boats, trailers, bilges, live wells, or bait buckets and can stay alive for weeks if kept moist.

Eurasian watermilfoil Myriophyllum spicatum

4�

Wild parsnipPastinaca sativa

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4�

Herbaceous, monocarpic (flowers once and dies) perennial. Grows as a rosette with upright leaves, persisting for at least � year. Flowering stems are stout, hollow, grooved, and up to 5’ tall.

Leaves: Rosette leaves are pinnately compound with 5-15 broad, ovate to oblong leaflets. Stem leaves are alternate, with �-5 pairs of opposite, sharply-toothed leaflets. Petioles wrap around the stem. Upper stem leaves are reduced to nar-row bracts.

Flowers: Numerous, small, 5-petaled, yellow flowers in umbels 2-6” wide at the tops of stems and branches. Blooms from late spring to mid-summer.

Fruits & seeds: Seeds are flat, round, yellowish, and slightly ribbed. Seeds remain viable in soil for 4 years.

Roots: Long, thick taproot.

CAUTION: When sap contacts skin in the presence of sunlight, it can cause severe rashes, blisters, and discoloration of the skin (phyto-

photodermatitis). Wear gloves, long sleeves, and long pants when handling.

Ecological threat:• Wild parsnip invades prairies, oak savannas, and fens as well as roadsides, old fields, and pastures. • It has a broad habitat tolerance, growing in dry, mesic, or wet habitats, but it does not grow in shaded areas.• A native of Europe and Asia, this plant is be-lieved to have escaped from cultivation, as it was once grown as a root vegetable.

Wild parsnip Pastinaca sativa

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Reed canarygrassPhalaris arundinacea

4�

44

Perennial, sod-forming, cool season grass with erect, hairless stems that grow �-6’ tall.

Leaves: Flat blades with rough texture on both surfaces, gradually tapering, 0.�5-0.75” wide, and �.5-�0” long. Ligule is highly transparent.

Flowers: Flower heads �-6” long, and green to purple changing to beige over time. Branches of inflorescence spreading when in bloom but held close to stem at maturity. Bloom mid- to late spring.

Fruits & seeds: Shiny, brown, and able to germi-nate immediately upon maturation.

Roots: Rhizomes with large numbers of dormant buds create a thick mat at or just below the soil surface.

Similar species: Reed canarygrass can be distinguished from the native bluejoint grass (Calamagrostis canadensis), by its ligule. Reed canarygrass has a transparent ligule; bluejoint does not.

Ecological threat:• Reed canarygrass dominates a significant num-

ber of wetlands in the Midwest and also spreads into forests and upland grasslands.• It forms dense, persistent monospecific stands in wetlands, moist meadows, and riparian areas. These stands outcompete desirable native plants, and are of little use to wildlife. • Reed canarygrass constricts water flow by trapping silt. It can also promote erosion where water cuts away soil under its dense rhizome mat.• It was introduced to the U.S. in the mid-�800s for forage and erosion control. It continues to be widely planted throughout the country.• Extensive rhizomes and dormant buds make it extremely difficult and expensive to control.

Reed canarygrass Phalaris arundinacea

45

Common reed (or phragmites)Phragmites australis

45

46

Perennial grass, �-�0’ tall with cane-like stems, up to �” in diameter.

Leaves: Long and tapering, �-�.5” wide at the base, �0-�0” long, and smooth on blade but rough on the margins. Usually blue-green, as opposed to the yellow-green leaves of native varieties, but may be yellow-green in brackish habitats.

Flowers: Large, feathery panicles (loose branch-ing inflorescences), 5-16” long, purple-brown, turning golden brown with age. Bloom in late summer.

Fruits & seeds: May produce thousands of seeds annually, but viability is typically low.

Roots: Dense network of roots and rhizomes, up to 6’ deep. Rhizomes can grow over �0’ per year.

Similar species: In North America, both native and introduced subspecies of Phragmites australis are found. Introduced Phragmites is highly ag-gressive, forming dense stands that include both live stems and standing dead stems from the previous year’s growth. In native varieties, both

leaves and leaf sheaths are loose and usually drop as the plant senesces, but in introduced Phragmites leaf sheaths typically adhere tightly to dead stems. See www.invasiveplants.net for more information on distinguishing native and non-native strains.

Ecological threat: • Common reed is found in tidal and nontidal brackish and freshwater marshes, river edges, shores of lakes and ponds, ditches, roadsides, and disturbed areas. • Once it invades a site, it can quickly form a monospecific stand, excluding native plants, changing hydrology, altering wildlife habitat, and increasing fire potential.

Common reed (or phragmites) Phragmites australis

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Japanese knotweedPolygonum cuspidatum (also known as Fallopia japonica)

47

48

Arching herbaceous perennial, up to �0’ tall. Hollow, reddish, bamboo-like stems are smooth and stout often persisting after plant dies back to the ground each year. The base of the stem above each joint is swollen and surrounded by a membranous sheath.

Leaves: Alternate, egg-shaped to almost triangu-lar, 4-6” long, �-4” wide. Dark green on upper surface, and pale green on lower surface.

Flowers: Branched inflorescences of tiny, creamy white or greenish flowers emerge from leaf axils, near the ends of stems. Bloom in late summer.

Fruits & seeds: Small, winged, triangular fruits carry very small, shiny seeds.

Roots: Grow up to 6’ deep. Spreads rapidly via long, stout rhizomes, which can reach 65’ or more from parent plants.

Similar species: Giant knotweed (P. sachalinense) is also invasive, but is up to ��’ tall with larger leaves. The two species are known to hybridize.

Ecological threat:• Japanese knotweed poses a significant threat to riparian areas, where it can rapidly colonize. It tolerates full shade, high temperatures, high salinity, and drought.• It spreads vegetatively to form dense thickets that suppress other vegetation in upland and lowland areas.• It can be transported to new sites as a contami-nant in fill dirt or on equipment. During floods, it spreads downstream by shoot fragments, rhi-zomes, or occasionally by seeds. Escapees from neglected gardens and discarded cuttings are common routes of dispersal from urban areas.

Japanese knotweed Polygonum cuspidatum (also known as Fallopia japonica)

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Common buckthorn Rhamnus cathartica

Glossy buckthorn Frangula alnus

49

50

Shrubs up to 20-25’ tall, often with several stems arising from base, and spreading crowns. Gray to brown bark with prominent light-colored lenticels.

Leaves: Ovate or elliptic, with prominent veins curving toward tip. Stay green late into fall. R. cathartica has mostly opposite leaves, �-�.5” long, with tiny teeth. F. alnus has entire, mostly alter-nate leaves, �-�” long, with glossy upper surface and dull underside that may be hairy.

Flowers: Small and clustered in leaf axils. R. cathartica has fragrant, greenish-yellow, 4-petaled flowers that bloom in spring. F. alnus has small, pale yellow, 5-petaled flowers that bloom from mid-spring to first frost.

Fruits & seeds: Both species have abundant clus-ters of round, pea-sized fruit. R. cathartica fruit is black, and F. alnus fruit is red to dark purple. Dispersed by birds and mammals.

Similar species: Alder buckthorn (Rhamnus alni-folia; native) is under �’ tall with thornless twigs. Lance-leafed buckthorn (R. lanceolata; native) is less than 6’ tall, found in wet areas, and has

alternate leaves, �-6” long, gradually tapering to a point at the tip. Carolina buckthorn (Rhamnus caroliniana; native), found in the southern Mid-west, is �0-�0’ tall and similar to F. alnus but with toothed leaves.

Ecological threat:• Common buckthorn invades forests, prairies, old fields, and roadsides. Glossy buckthorn is an aggressive invader of wetlands and also grows well in a wide variety of upland habitats. • Buckthorns can form dense, even-aged thick-ets, reducing light availability for understory species and preventing native tree regeneration. • Both buckthorns have broad environmental tolerance. They leaf out very early and retain their leaves late in the growing season, giving them a longer growing season than native plants.

Rhamnus cathartica Frangula alnus

Common buckthorn Rhamnus catharticaGlossy buckthorn Frangula alnus (also known as Rhamnus frangula)

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Black locustRobinia pseudoacacia

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5�

Fast-growing tree in the legume family, grows �0-90’ tall with a trunk �-4’ in diameter. Forms multiple-stemmed clones and is slow to leaf out in spring. Seedlings and small branches have paired thorns. Bark is smooth and green on saplings, but dark with deep furrows on mature trees.

Leaves: Alternate, pinnately compound with 7-21 leaflets, arranged in pairs with one unpaired leaflet at the tip. Leaflets are thin, entire, elliptic, bluish-green above and pale beneath.

Flowers: White, pea-like, very fragrant, in showy, drooping inflorescences. Bloom in mid-spring.

Fruits & seeds: Flat, shiny brown pods, �-6” long, contain 4 to 8 seeds. Pods often persist on tree through winter.

Roots: Extensive system of fibrous roots and shallow rhizomes. Reproduces vegetatively by root suckering and stump sprouting.

CAUTION: Leaves, seeds, and bark are toxic to livestock and humans if ingested.

Ecological threat:• Black locust invades forests, upland prairies and savannas, pastures, old fields, and road-sides. Its vigorous vegetative reproduction forms extensive, dense groves of clones that exclude native vegetation.• Damage to roots or stems (such as from fire, wind, cutting, or disease) stimulates vigorous sprouting, root suckering, and lateral spread. • Black locust is native to the U.S., including some parts of southern Indiana, Illinois, Ohio, and Missouri. It has been extensively planted for its nitrogen-fixing qualities and its hard wood and has become an aggressive invader in areas where it is introduced.

Black locust Robinia pseudoacacia

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Multiflora roseRosa multiflora

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Thorny, thicket-forming shrub with wide, arch-ing or climbing canes and stiff, curved thorns. Can reach �0-�5’ tall and 9-��’ wide.

Leaves: Alternate, pinnately compound with 5-11 small (0.5-1”) sharply-toothed oval leaflets, nearly smooth on upper surface and paler with short hairs on underside. Pair of fringed stipules (small, leaf-like appendages) at base of each leaf.

Flowers: Abundant, showy, fragrant, and white to slightly pink, with styles about as long as sta-mens. Flowers form a loose inflorescence from 0.5-�.5” across. Blooms mid- to late spring.

Fruits & seeds: Small (0.�5” in diameter), hard, bright red fruits, or rose hips, develop in sum-mer, become brownish-red at maturity, and remain on plant through winter. Produces up to 500,000 seeds per year. Dispersed by birds and mammals.

Roots: Older plants may have a root crown di-ameter of 8” or more. Canes may produce roots when in contact with soil.

Similar species: Native roses are distinguished

by stipules with entire margins and slender, straight thorns. Most native roses also have pink flowers.

Ecological threat:• Multiflora rose invades open woodlands, forest edges, successional fields, roadsides, savannas, and prairies. • It is extremely prolific and can form impen-etrable thickets that exclude native plant species. • Introduced from Japan in �886 as rootstock for cultivated roses, it has been planted widely to curb soil erosion, as a living fence, and as a source of food and cover for wildlife.

Multiflora rose Rosa multiflora

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Crown vetchSecurigera varia (also known as Coronilla varia)

55

56

Herbaceous perennial with trailing stems that forms dense colonies, growing �-6’ long. In win-ter and early spring, crown vetch can be easily recognized as large, brown patches.

Leaves: Pinnately compound, alternate, �-6” long, with 11-25 elliptic leaflets occuring in an odd number.

Flowers: Pea-like, ranging in color from pink or lavender to white. Flowers are clustered in flat-topped umbels of 14-20 flowers that grow on extended stalks from the leaf axils. Bloom from mid-spring through mid-summer.

Fruits & seeds: Long, slender, pointed seed pods contain �-7 slender seeds each. Seeds remain viable in the soil for up to �5 years.

Roots: Reproduces vegetatively by fleshy rhi-zomes that grow up to �0’ long. Roots are not fibrous, limiting the utility of crown vetch for erosion control.

Ecological threat:• Crown vetch invades grasslands and dunes,as well as agricultural lands and roadsides.

• It prefers open, sunny areas and can withstand periods of drought. • Crown vetch alters native ecosystems through nitrogen fixation, creating increased fuel load for fires, and shading out native plants. • It was introduced from the Mediterranean region during the �950s for erosion control, but it is also planted as a cover crop and an ornamen-tal and spreads from plantings.

Crown vetch Securigera varia (also known as Coronilla varia)

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Narrow-leaved cattail Typha angustifolia

Hybrid cattail Typha x glauca

57

58

Perennial, grass-like, wetland plant with submersed stalks. Hybrid cattail is a hybrid of common and narrow-leaved cattails.

Leaves: Erect, linear, flat, very narrow (0.25-0.5” wide), and �’-6’ long. ��-�6 leaves arise from base of each shoot. Flowers: Dense cylindrical spike at end of stem. Inflorescence divided into upper section of yellow, male flowers and lower brown sausage-shaped section of female flowers. Gap between male and female flowers is 0.4-0.5” in narrow-leafed cattail and 0-2” in hybrid cattail.

Fruits & seeds: Cigar-shaped, �-6” long, with soft, downy seeds. Produces up to 250,000 seeds per year. Seeds remain viable in the soil for up to �00 years.

Roots: Starchy rhizomes grow rapidly and may form a dense mat.

Similar species: Common cattail (Typha latifolia; native) is taller, generally more robust, and does not have a gap between male and female flowers.

Ecological threat:• Cattails are common in freshwater marshes, along highways, in ditches and shallow ponds, at the edges of calm waters, and in consistently damp patches of rural and suburban yards.• They have a wide range of habitat tolerance and are able to withstand water pollution and altered hydrology.• Cattails play an important role as a source of food and shelter for some marsh-dwelling ani-mals, but large monospecific stands of invasive cattails exclude other, more valuable, wildlife food and cover species.

Typha angustifolia Typha x glauca

Narrow-leaved cattail Typha angustifoliaHybrid cattail Typha x glauca

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Watch List: This guide highlights the most common and widespread invasive plants in the Midwest, but tdoes not include all invasive plants. This watch list includes species that are (�) cur-rently less widespread in our region but highly invasive in some areas; (�) invasive in other parts of the country and are just beginning to arrive in the Midwest; and (�) species that have been heavily planted in cultivated areas and are beginning to move into natural areas throughout the region. To find more information on these species, see the Other Resources section of this guide.

Species Common name States reported in

Acer platanoides Norway maple IL, IN, MI, MN, OH, WI

Ampelopsis brevipedunculata porcelainberry IA, IL, MI, OH, WI

Butomus umbellatus flowering rush IL, IN, MI, MN, OH, WI

Cirsium palustre European marsh thistle MI, WI

Cynanchum louisiae black swallowwort IL, IN, MI, MO, MN, OH, WI

Cynanchum rossicum pale swallowwort IN, MI, MO

Dioscorea oppositifolia Chinese yam IL, IN, MO, OH

Egeria densa Brazilian elodea IL, IN, MO, MN

Euonymus alatus burning bush IA, IL, IN, MI, MO, OH, WI

Gypsophila paniculata baby’s breath IA, IL, IN, MI, MN, OH, WI

Heracleum mantegazzianum giant hogweed IL, OH, MI, WI

Hieracium aurantiacum orange hawkweed IA, IL, IN, MI, MN, OH, WI

Humulus japonicus Japanese hops IA, IL, IN, MI, MO, MN, OH, WI

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Species Common name States reported in

Hydrilla verticillata hydrilla IN, WI

Hydrocharis morsus-ranae European frog-bit IL, MI

Iris pseudacorus yellow flag iris IL, IN, MI, MO, MN, OH, WI

Lepidium latifolium perennial pepperweed IL, IN, MO, WI

Lespedeza cuneata sericea lespedeza IA, IL, IN, MI, MO, OH, WI

Lotus corniculatus bird’s-foot trefoil IA, IL, IN, MI, MO, MN, OH, WI

Myriophyllum aquaticum parrot feather IA, IL, IN, MO, OH

Najas minor lesser naiad IA, IL, IN, MI, MO, MN, OH

Polygonum perfoliatum mile-a-minute OH

Potamogeton crispus curlyleaf pondweed IA, IL, IN, MI, MO, MN, OH, WI

Pueraria montana kudzu IL, IN, MO, OH

Pyrus calleryana Callery pear IL, IN, OH

Quercus acutissima sawtooth oak not reported

Ranunculus ficaria lesser celandine IL, IN, MI, MO, OH, WI

Torilis arvensis field hedge parsley IA, IL, IN, MO, OH

Torilis japonica Japanese hedge parsley IA, IL, IN, MI, MO, OH, WI

Trapa natans water chestnut MO

* Data were taken from USDA PLANTS Database in July �008 and maps developed for MIPN’s “Keep a Lookout” flyers.

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Species that need to be maintained:Some cultivated ground cover species can invade natural areas when not properly maintained.

Species Common Name States reported in

Euonymus fortunei winter creeper IL, IN, MI, MO, OH, WI

Hedera helix English ivy IL, IN, MI, MO, OH

Vinca minor common periwinkle IA, IL, IN, MI, OH, WI

These three species can be prevented from being invasive by following these guidelines:

�) Plant these species only next to concrete or lawns. Do not plant them next to natural areas.�) Do not let them climb. English ivy and winter creeper may produce fruits if allowed to climb. These fruits can be dispersed by birds and other animals.

References and Other Resources:Books and field guides:Invasive Plants Field & Reference Guide: An Ecological Perspective of Plant Invaders of Forests and Woodlands by Cynthia D. Huebner, USDA Forest Service, �006Invasive Plants: Guide to Identification and the Impacts and Control of Common North American Species by Sylvan Ramsey Kaufman & Wallace Kaufman, Stackpole Books, �007Invasive Plants of the Southern Tier, USFS Region 9 by Carol Mortensen, USDA Forest Service, �00�Invasive Plants of the Upper Midwest by Elizabeth Czarapata, Univeristy of Wisconsin Press, �005Manual of Vascular Plants of Northeastern United States and Adjacent Canada, Second Edition by Henry A. Gleason and Arthur Cronquist, The New York Botanical Garden, �99�Minnesota Invasive Non-native Terrestrial Plants: An Identification Guide for Natural Resource Managers by the Minnesota Department of Natural Resources, �00�

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Weeds of the North Central States, North Central Regional Research Publication No. �8�, Bulletin 77�, University of Illinois at Urbana-Champaign, �98�Weeds of the Northeast by Richard Uva, Joseph C. Neal, and Joseph M. DiTomaso, Cornell University Press, �007Weeds of the Northern Lakes States by Carol Estes Mortensen, USDA Forest Service, �00�Weeds of the Northern U.S. and Canada, by France Royer & Richard Dickinson, The University of Alberta Press & Lone Pine Publishing, �999Weeds of the West by Tom D. Whitson, Larry C. Burrill, Steven A. Dewey, David W. Cudney, B. E. Nelson, Richard D. Lee, & Robert Parker, The Western Society of Weed Science, 5th edition, �999

Websites:Midwest Invasive Plant Network, www.mipn.orgPlant Conservation Alliance, Weeds Gone Wild: Alien Plant Invaders of Natural Areas, www.nps.gov/plants/ALIEN/The Nature Conservancy’s Global Invasive Species Team, http://tncweeds.ucdavis.eduUSDA PLANTS database, www.plants.usda.gov

Papers & reports:Stinson, K.A., et al. �006. Invasive plant supresses the growth of native tree seedlings by disrupting belowground mutualisms. PLoS Biol 4(5): e�40.Pavlovic, N., et al. �007. American and Oriental Bittersweet Identification, U.S. Geological Survey, Great Lakes Science Center, GLSC Fact Sheet �007-�.Schierenbeck, K., et al. 1994. Effects of herbivory on growth and biomass allocation in native and introduced species of Lonicera. Ecology 75 (6) �66�-�67�.

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Photo Credits

Page 6, tree-of-heaven: Forest Preserve District of DuPage Co., IL (leaf); Debbie Maurer, Lake Co. Forest Preserve District, IL (tree, samaras); Page 8, garlic mustard: Nathan Tucker, Fort McCoy Wildlife Prog. (whole plant); Chris Evans, River to River CWMA (flowers); Paul Rothrock, Taylor University (leaves); Page 10, Japanese barberry: Paul Rothrock, Taylor University (flowers and leaves); Melissa Moser, Ohio Div. of Natural Areas & Preserves (shrub); Nathan Tucker (fruit); Page 12, musk thistle: Paul Rothrock, Taylor University (flower); Minnesota Dept. of Agricul-ture (leaf); Peter Dziuk (rosette); Page 14, Asian bittersweet: Debbie Maurer, Lake Co. Forest Preserve District, IL; Page 16, spotted knapweed: Peter Dziuk (flower, rosette); Minnesota Dept. of Agriculture (leaves); Page 18, Canada thistle: Paul Rothrock, Taylor University (flower); Peter Dziuk (rosette, seedheads); Page 20, crown vetch: Nathan Tucker, Fort McCoy Wildlife Prog. (flowers); Peter Dziuk (infestation); Minnesota Dept. of Agriculture (leaf); Page 22, common teasel: Paul Rothrock, Taylor University (flower, rosette); cut-leaved teasel: Debbie Maurer, Lake Co. Forest Preserve District, IL; Peter Dziuk (seedheads); Page 24, autumn olive: Paul Rothrock, Taylor University; Rus-sian olive: John Randall, The Nature Conservancy; Page 26, leafy spurge: Debbie Maurer, Lake Co. Forest Preserve District, IL; Page 28, dame’s rocket: Forest Preserve District of DuPage Co., IL (rosette); Peter Dziuk (flowers); Page 30, privet: Katherine Howe, MIPN (leaves & flowers); Melissa Moser, Ohio Div. of Natural Areas & Pre-serves (shrub); Page 32, Japanese honeysuckle: Katherine Howe, MIPN; Page 34, Asian bush honeysuckles: Paul Rothrock, Taylor University (flower close-up); Peter Dziuk (fruits); Melissa Moser, Ohio Div. of Natural Areas & Preserves (flowering shrub); Page 36, purple loosestrife: Katherine Howe, MIPN (flowers); Mike Norris, The Nature Conservancy (plant); Page 38, sweetclovers: Nathan Tucker, Fort McCoy Wildlife Prog. (whole plant); Peter Dziuk (white flowers); Paul Rothrock (yellow flowers); Page 40, Japanese stiltgrass: Luke Flory, Indiana University; Page 42, Eurasian watermilfoil: Scott Namestnik, JF New (flowers); Kim Bogenschutz, Iowa DNR (infestation, leaves); Page 44, wild parsnip: Nathan Tucker, Fort McCoy Wildlife Prog.; Page 46, reed canarygrass: Ellen Jacquart, The Nature Conservancy (seedheads, whole plant); Peter Dziuk (leaves); Page 48, common reed: Peter Dziuk (infesta-tion shots); Melissa Moser, Ohio Div. of Natural Areas & Preserves (seedheads); Page 50, Japanese knotweed: Katherine Howe, MIPN; Page 52, common buckthorn: Paul Rothrock, Taylor University; glossy buckthorn: Melissa Moser, Ohio Div. of Natural Areas & Preserves; Page 54, black locust: Marcia Moore, Friesner Herbarium at Butler University (flowers); Katherine Howe, MIPN (leaf); Forest Preserve District of DuPage Co., IL (bark, pods); Page 56, multiflora rose: Katherine Howe, MIPN (flowers); Melissa Moser, Ohio Div. of Natural Areas & Preserves (shrub); Nathan Tucker (fruits); Page 58, cattails: Joy Marburger, National Park Service

64

Ailanthus altissima, 5-6Alliaria petiolata, 7-8Asian bittersweet, 13-14autumn olive, ��-��Berberis thunbergii, 9-�0black locust, 5�-5�buckthorn, common, 49-50buckthorn, glossy, 49-50Canada thistle, �7-�8Carduus acanthoides, ��Carduus nutans, ��-��cattail, hybrid, 57-58cattail, narrow-leaved, 57-58Celastrus orbiculatus, ��-�4Centaurea stoebe, �5-�6Centaurea maculosa, �5-�6Cirsium arvense, �7-�8common reed, 45-46Coronilla varia, 55-56crown vetch, 55-56cypress spurge, �4dame’s rocket, �5-�6Dipsacus fullonum, �9-�0Dipsacus laciniatus, �9-�0 Dipsacus sylvestris, �9-�0Elaeagnus angustifolia, ��-��Elaeagnus umbellata, ��-��Euphorbia cyparissias, �4Euphorbia esula, ��-�4Eurasian watermilfoil, �9-40Fallopia japonica, 47-48

Frangula alnus, 49-50garlic mustard, 7-8Hesperis matronalis, �5-�6honeysuckle, Asian bush, ��-��honeysuckle, Japanese, �9-�0Japanese barberry, 9-�0Japanese stiltgrass, �7-�8knotweed, giant, 48knotweed, Japanese, 47-48leafy spurge, ��-�4Ligustrum japonicum, �8Ligustrum obtusifolium, �7-�8Ligustrum sinense, �8Ligustrum vulgare, �7-�8Lonicera japonica, �9-�0Lonicera maackii, ��-��Lonicera morrowii, ��-��Lonicera tatarica, ��-��Lonicera x bella, ��-��Lythrum salicaria, ��-�4Melilotus alba, �5-�6Melilotus officinalis, �5-�6Microstegium vimineum, �7-�8multiflora rose, 53-54musk thistle, ��-��Myriophyllum spicatum, �9-40Nepalese browntop, �7-�8nodding thistle, ��-��Pastinaca sativa, 4�-4�Phalaris arundinacea, 4�-44Phragmites australis, 45-46

plumeless thistle, ��Polygonum cuspidatum, 47-48Polygonum sachalinense, 48privet, border, �7-�8privet, common, �7-�8privet, Chinese, �8privet, Japanese, �8purple loosestrife, ��-�4reed canarygrass, 4�-44Rhamnus cathartica, 49-50Rhamnus frangula, 49-50Robinia pseudoacacia, 5�-5�Rosa multiflora, 5�-54Russian olive, ��-��Securigera varia, 55-56spotted knapweed, 15-16sweetclover, white, �5-�6sweetclover, yellow, �5-�6teasel, common, �9-�0teasel, cut-leaved, �9-�0tree-of-heaven, 5-6Typha angustifolia, 57-58Typha x glauca, 57-58wild parsnip, 4�-4�

Index

65

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