Resource - The Stewardship Network

A Field Guide to
Invasive Plants of the Midwest
Edited by Katherine Howe, Mark Renz, Kelly Kearns, Jennifer Hillmer, & Ellen Jacquart
Credits: This guide was adapted from “Minnesota invasive non-native terrestrial plants: an identification guide for natural resource managers” by the Minnesota Department of Natural Resources.
Additional editing was provided by Trish Beckjord, Kim Bogenschutz, Carmen Chapin, Joy Marburger, 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; common buckthorn, Paul Rothrock; common reed, Melissa Moser, Ohio DNAP
Center: 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, Katherine Howe; garlic mustard, Chris Evans
Color-coded pages: Colored bars at the tops of pages indicate growth form. Colors are used as follows: 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.
Table of Contents (alphabetized by botanical name)
Credits and map legend ........................................2
Introduction .............................................................4
Tree-of-heaven, Ailanthus altissima .......................5
Garlic mustard, Alliaria petiolata ...........................7
Japanese barberry, Berberis thunbergii ...................9
Musk thistle, Carduus nutans ...............................11
Asian bittersweet, Celastrus orbiculatus ...............13
Spotted knapweed, Centaurea stoebe ..................15
Canada thistle, Cirsium arvense ............................17
Common teasel & cut-leaved teasel,
Dipsacus fullonum & D. laciniatus .......................19
Autumn & Russian olives,
Elaeagnus umbellata & E. angustifolia .................21
Leafy spurge, Euphorbia esula .............................23
Dame’s rocket, Hesperis matronalis .......................25
Blunt-leaved & common privets,
Ligustrum obtusifolium & L. vulgare ..................27
Japanese honeysuckle, Lonicera japonica ............29
Asian bush honeysuckles, Lonicera maackii,
L. morrowii, L. tatarica, & L. x bella ....................31
Purple loosestrife, Lythrum salicaria ......................33
White & yellow sweetclovers,
Melilotus alba & M. officianalis ............................35
Japanese stiltgrass, Microstegium vimineum ........37
Eurasian watermilfoil, Myriophyllum spicatum ...39
Wild parsnip, Pastinaca sativa ...........................41
Reed canarygrass, Phalaris arundinacea ................43
Common reed, Phragmites australis .......................45
Japanese knotweed, Polygonum cuspidatum ........47
Common & glossy buckthorns,
Rhamnus cathartica & Frangula alnus ...................49
Black locust, Robinia pseudoacacia ........................51
Multiflora rose, Rosa multiflora .........................53
Crown vetch, Securigera varia ................................55
Narrow-leaved & hybrid cattails,
Typha angustifolia & Typha x glauca ...................57
Watch list ..........................................................59-61
References and other resources ....................61-62
Glossary ............................................................63-64
Photo credits .........................................................65
Introduction
Invasive 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-fitsmost prescription for invasive species management, but we know that persistent removal and restoration 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.
Tree-of-heaven
Ailanthus altissima
5
Tree-of-heaven Ailanthus altissima
Rapidly-growing tree. Mature trees can be 80’
tall or more. Trunk is 1-2’ in diameter. Tree-ofheaven 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.
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.
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 350,000 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-
Garlic mustard
Alliaria petiolata
7
Garlic mustard Alliaria petiolata
Herbaceous biennial with stems 2-4’ tall. Firstyear 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, heartshaped, with large teeth. Stem leaves on flowering plants are alternate, triangular, with large
teeth, and can be 2-3” across. Leaves and stems
smell like garlic when crushed.
Flowers: Small, white, 4-petaled, and abundant.
Bloom throughout the spring.
Fruits & seeds: Up to 3,000 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.
plain forests and savannas, as well as disturbed
areas such as yards and roadsides. It is sometimes 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.
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-
Japanese barberry
Berberis thunbergii
9
Japanese barberry Berberis thunbergii
Small, round, dense, spiny shrub, typically
2-3’ 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. Arranged in clusters above single spines.
Flowers: Small, yellow, umbrella-shaped, with
6 petals. Single or in clusters of 2-4. Bloom in
mid-spring.
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 1875. It is commonly planted for
ornamental purposes, as well as for wildlife and
erosion control. Some cultivars produce fewer
seeds than others.
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 natural habitats including forests, woodlands, oak
10
Musk thistle (or nodding thistle)
Carduus nutans
11
11
Musk thistle (or nodding thistle) Carduus nutans
Herbaceous biennial, 1-7’ tall, with a multibranched 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 1-3” wide and droop to a 90°
angle from the stem when mature.
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 1-4’ 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.
Roots: Taproot.
Fruits & seeds: Seeds are yellowish-brown, with
a bristly, white pappus. Each plant may produce
up to 10,000 seeds. Seeds remain viable in the
soil for 10 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
12
Asian bittersweet
Celastrus orbiculatus
13
Asian bittersweet Celastrus orbiculata
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 margins, 2-5” long.
Flowers: Small, inconspicuous, 5-petaled, greenish-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 redorange, fleshy fruits, each containing one or two
seeds. Dispersed by birds and small mammals.
Ecological threat:
• Asian bittersweet grows rapidly and is tolerant
of a wide range of habitats.
• It infests forests, woodlands, fields, hedgerows, and coastal areas and can grow in open
sites or under a closed forest canopy.
• Asian bittersweet may damage trees by girdling 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 mistaken for American bittersweet.
Roots: Spreading underground roots can sprout
to form new stems.
Similar species: American bittersweet (Celastrus 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.
14
Spotted knapweed
Centaurea stoebe (also known as Centaurea maculosa)
15
Spotted knapweed Centaurea stoebe (also known as Centaurea maculosa)
Herbaceous, short-lived perennial, 2-4’ tall.
Persists as a rosette 1-4 years before bolting.
Flowering plants usually have 1-6 stems, but
may have up to 20.
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
(1-3” 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 1,000 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.
CAUTION: Wear long sleeves and gloves when
handling. Spotted knapweed exposure can
irritate skin in some people.
Ecological threat:
• Spotted knapweed threatens dry areas, including 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 sedimentation and decreased water-holding capacity
in soil.
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.
16
Canada thistle
Cirsium arvense
17
Canada thistle Cirsium arvense
Herbaceous perennial, 2-6.5’ tall with upright,
grooved stems that branch near top of plant.
Native to Eurasia, despite the widely-used common name.
Leaves: Alternate, oblong, irregularly lobed, tapering, 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.
roots; (2) dense clonal growth; and (3) small
dioecious flower heads.
Ecological threat:
• Canada thistle invades open natural areas such
as prairies, savannas, glades, dunes, streambanks, sedge meadows, and forest openings. It
also invades croplands, pastures, forest openings, lawns and gardens, roadsides, ditches, and
waste sites.
• Once it has established it spreads quickly,
forming monospecific stands and replacing native plants.
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 20 years.
Roots: Reproduces clonally by creeping roots
that grow laterally in soil, up to 10-12’ 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 (1) creeping lateral
18
Common teasel
Dipsacus fullonum
Cut-leaved teasel
Dipsacus laciniatus
19
Common teasel Dipsacus fullonum (also known as Dipsacus sylvestris)
Cut-leaved teasel Dipsacus laciniatus
Herbaceous, monocarpic (flowers once and dies)
perennial. Grows as a basal rosette for at least
one year. Forms a prickly, angled flowering
stalk, 2-6’ tall, typically in second or third year.
Leaves: Opposite, large (up to 1.5’ 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.
Ecological threat:
• Teasel grows in open areas, including prairies,
savannas, and sedge meadows, as well as roadsides 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.
Flowers: Hundreds of small flowers clustered in
dense, egg-shaped heads. Stiff, spiny, leaf-like
bracts curve up from base of flower head. Common 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 2,000 seeds. Seeds remain viable in the soil for
at least 2 years.
Dipsacus fullonum
Dipsacus laciniatus
Roots: Deep taproot, up to 2’ long and 1” in
diameter.
20
Autumn olive
Elaeagnus umbellata
Russian olive
Elaeagnus angustifolia
21
Autumn olive Elaeagnus umbellata
Russian olive Elaeagnus angustifolia
Large shrub or small tree with silvery foliage.
Autumn olive grows up to 20’. Russian olive can
reach up to 30’ and has thorny branches.
Leaves: Simple and alternate. Autumn olive’s
leaves are silver-gray on the underside, lanceshaped 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. Autumn olive flowers are light yellow. Russian olive 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 olivelike. Both dispersed by birds.
having opposite leaves that are silver on both
sides.
Ecological threat:
• Autumn olive invades open and forested natural 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.
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
Elaeagnus umbellata
Elaeagnus angustifolia
22
Leafy spurge
Euphorbia esula
23
Leafy spurge Euphorbia esula
Herbaceous perennial, 2-3’ 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 surrounded by cup-shaped bracts. Flowers are paired,
with 7-10 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
250 seeds. Seeds remain viable in the soil for up
to 8 years. Dispersed by wildlife, humans, and
water.
cyparissias) is another invasive plant similar in
appearance, but it grows to 1’ with narrower
leaves.
Ecological threat:
• Leafy spurge spreads rapidly in open areas, including 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.
Roots: Extensive root system with taproots extending up to 15’ deep and lateral roots spreading up to 35’. New sprouts from root buds
facilitate spread into undisturbed areas.
Similar species: Cypress spurge (Euphorbia
24
Dame’s rocket
Hesperis matronalis
25
Dame’s rocket Hesperis matronalis
Showy, short-lived perennial or biennial, 3-4’ tall.
First-year leaves form a basal rosette that overwinters. 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 2 short.
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 1600s. 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.
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
26
Border privet & common privet
Ligustrum obtusifolium & Ligustrum vulgare
27
Border privet or blunt-leaved privet Ligustrum obtusifolium
Common privet or European privet Ligustrum vulgare
Perennial shrub or small tree with spreading
branches, growing 12-15’ tall, though it may
reach up to 30’. 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 difficult to distinguish.
Leaves: Opposite, elliptic to ovate, with entire
margins, leathery, tough, and 1-2” long.
Flowers: White, with 4 petals fused into a tube,
occurring in dense terminal inflorescences. Very
abundant and strongly scented. Bloom in early
summer.
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 cultivation to invade adjacent areas, rapidly forming
dense thickets that displace many native species.
• Privet has been commonly used as an ornamental shrub or hedgerow since its introduction
to the United States in the early 1800s.
• Once established, it is very difficult to remove.
Fruits & seeds: Abundant, ovoid, containing 1-4 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 appearance. Both are invasive in some parts of the
Ligustrum obtusifolium
Ligustrum vulgare
28
Japanese honeysuckle
Lonicera japonica
29
Japanese honeysuckle Lonicera japonica
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, 1.5-3”
long, sometimes lobed, may be covered with
fine, soft hairs. Leaves persist on vine until midwinter.
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.
Ecological threat:
• Japanese honeysuckle invades forests, prairies,
fields, and roadsides.
• Japanese honeysuckle has an advantage over
the native trumpet honeysuckle (Lonicera sempervirens), 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.
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.
30
Asian bush honeysuckles
Lonicera maackii, L. morrowii, L. tatarica, & L. x bella
31
Asian bush honeysuckles Lonicera maackii, L. morrowii, L. tatarica, & L. x bella
Dense, multi-stemmed shrubs, 6-12’ 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 yellow 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 flowers and grow in dry or rocky sites. Native species develop leaves 1-2 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, roadsides, pastures, and old fields.
• They can rapidly form a dense shrub layer that
excludes native understory plants, decreases species richness, and reduces canopy tree growth.
• They alter habitats by decreasing light availability, 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, nutrientrich 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
32
Purple loosestrife
Lythrum salicaria
33
Purple loosestrife Lythrum salicaria
Herbaceous perennial, 3-7’ tall, with 4-, 5-, or
6-sided, somewhat woody stems. Mature plants
have multiple stems (30-50) originating from a
woody crown.
Leaves: Opposite, or occasionally alternate, pairs
alternating at 90° angles, 1-4” 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 2 million seeds per plant per year.
Seeds remain viable in soil for up to 20 years.
plants.
• Dense stands of purple loosestrife are unsuitable as cover, food, or nesting or spawning habitat 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 irrigation and drainage ditches.
• Supposedly sterile ornamental cultivars are
known to produce fertile seeds when able to
cross-pollinate with other cultivars or wild
populations.
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
34
White sweetclover & yellow sweetclover
Melilotus alba & Melilotus officinalis
35
White sweetclover Melilotus alba
Yellow sweetclover Melilotus officinalis
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
3-5’ 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.
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 1600s and are still used
today as forage crops and soil enhancers.
Flowers: Five-parted, small, white (M. alba) or
yellow (M. officinalis), fragrant, pea-like flowers,
clustered in dense racemes (unbranched inflorescences 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
350,000 seeds per plant. Seeds remain viable in
the soil for up to 30 years.
Melilotus alba
Melilotus officinalis
Roots: Strong taproot and extensive lateral roots.
36
Japanese stiltgrass (or Nepalese browntop)
Microstegium vimineum
37
Japanese stiltgrass (or Nepalese browntop) Microstegium vimineum
Annual grass 1-3’ (occasionally up to 5’) tall that
grows in a branching, sprawling, mat-like manner. Stems resemble a narrow, delicate bamboo.
Leaves: Pale green, alternate, narrow, lanceshaped, up to 3” 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 100-1,000
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 rightsof-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 conditions, it thrives in forest understories, spreading
rapidly to form extensive patches that displace
native species. It has become a dominant understory species in many eastern and midwestern
forests.
• Stiltgrass may change soil chemistry to its benefit by increasing soil pH and nitrate levels.
• White-tailed deer may facilitate its invasion
by feeding on native plant species and avoiding
stiltgrass.
38
Eurasian watermilfoil
Myriophyllum spicatum
393
Eurasian watermilfoil Myriophyllum spicatum
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
3-5 (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.
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 native 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.
Roots: Fibrous roots attach to sediments. Roots
develop along floating stems and allow stem
fragments to take root.
Similar species: Northern watermilfoil (M. sibiricum; 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.
40
Wild parsnip
Pastinaca sativa
41
Wild parsnip Pastinaca sativa
Herbaceous, monocarpic (flowers once and
dies) perennial. Grows as a rosette with upright
leaves, persisting for at least 1 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 2-5 pairs of opposite,
sharply-toothed leaflets. Petioles wrap around
the stem. Upper stem leaves are reduced to narrow 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 midsummer.
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 believed to have escaped from cultivation, as it was
once grown as a root vegetable.
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-
42
Reed canarygrass
Phalaris arundinacea
43
Reed canarygrass Phalaris arundinacea
Perennial, sod-forming, cool season grass with
erect, hairless stems that grow 2-6’ tall.
Leaves: Flat blades with rough texture on both
surfaces, gradually tapering, 0.25-0.75” wide,
and 3.5-10” long. Ligule is highly transparent.
Flowers: Flower heads 3-6” 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 germinate immediately upon maturation.
Roots: Rhizomes with large numbers of dormant
buds create a thick mat at or just below the soil
surface.
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-1800s
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.
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-
44
Common reed (or phragmites)
Phragmites australis
45
Common reed (or phragmites) Phragmites australis
Perennial grass, 3-20’ tall with cane-like stems,
up to 1” in diameter.
Leaves: Long and tapering, 1-1.5” wide at the
base, 10-20” 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 branching 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.
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.
Roots: Dense network of roots and rhizomes, up
to 6’ deep. Rhizomes can grow over 10’ per year.
Similar species: In North America, both native
and introduced subspecies of Phragmites australis
are found. Introduced Phragmites is highly aggressive, forming dense stands that include both
live stems and standing dead stems from the
previous year’s growth. In native varieties, both
46
Japanese knotweed
Polygonum cuspidatum (also known as Fallopia japonica)
47
Japanese knotweed Polygonum cuspidatum (also known as Fallopia japonica)
Arching herbaceous perennial, up to 10’ 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 triangular, 4-6” long, 3-4” 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.
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 contaminant in fill dirt or on equipment. During floods,
it spreads downstream by shoot fragments, rhizomes, or occasionally by seeds. Escapees from
neglected gardens and discarded cuttings are
common routes of dispersal from urban areas.
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 13’ tall with larger
leaves. The two species are known to hybridize.
48
Common buckthorn
Rhamnus cathartica
Glossy buckthorn
Frangula alnus
49
Common buckthorn Rhamnus cathartica
Glossy buckthorn Frangula alnus (also known as Rhamnus frangula)
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, 1-2.5” long,
with tiny teeth. F. alnus has entire, mostly alternate leaves, 2-3” 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 clusters 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 alnifolia; native) is under 3’ tall with thornless twigs.
Lance-leafed buckthorn (R. lanceolata; native)
is less than 6’ tall, found in wet areas, and has
alternate leaves, 2-6” long, gradually tapering to
a point at the tip. Carolina buckthorn (Rhamnus
caroliniana; native), found in the southern Midwest, is 10-30’ 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 thickets, 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
50
Black locust
Robinia pseudoacacia
51
Black locust Robinia pseudoacacia
Fast-growing tree in the legume family, grows
30-90’ tall with a trunk 2-4’ 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 midspring.
Ecological threat:
• Black locust invades forests, upland prairies
and savannas, pastures, old fields, and roadsides. 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.
Fruits & seeds: Flat, shiny brown pods, 2-6”
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.
52
Multiflora rose
Rosa multiflora
53
Multiflora rose Rosa multiflora
Thorny, thicket-forming shrub with wide, arching or climbing canes and stiff, curved thorns.
Can reach 10-15’ tall and 9-13’ wide.
by stipules with entire margins and slender,
straight thorns. Most native roses also have pink
flowers.
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.
Ecological threat:
• Multiflora rose invades open woodlands, forest
edges, successional fields, roadsides, savannas,
and prairies.
• It is extremely prolific and can form impenetrable thickets that exclude native plant species.
• Introduced from Japan in 1886 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.
Flowers: Abundant, showy, fragrant, and white
to slightly pink, with styles about as long as stamens. Flowers form a loose inflorescence from
0.5-1.5” across. Blooms mid- to late spring.
Fruits & seeds: Small (0.25” in diameter), hard,
bright red fruits, or rose hips, develop in summer, 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 diameter of 8” or more. Canes may produce roots
when in contact with soil.
Similar species: Native roses are distinguished
54
Crown vetch
Securigera varia (also known as Coronilla varia)
55
Crown vetch Securigera varia (also known as Coronilla varia)
Herbaceous perennial with trailing stems that
forms dense colonies, growing 2-6’ long. In winter and early spring, crown vetch can be easily
recognized as large, brown patches.
Leaves: Pinnately compound, alternate, 2-6”
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.
• 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 1950s for erosion control, but it
is also planted as a cover crop and an ornamental and spreads from plantings.
Fruits & seeds: Long, slender, pointed seed pods
contain 3-7 slender seeds each. Seeds remain
viable in the soil for up to 15 years.
Roots: Reproduces vegetatively by fleshy rhizomes that grow up to 10’ 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.
56
Narrow-leaved cattail
Typha angustifolia
Hybrid cattail
Typha x glauca
57
Narrow-leaved cattail Typha angustifolia
Hybrid cattail Typha x glauca
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 3’-6’ long. 12-16 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 sausageshaped section of female flowers. Gap between
male and female flowers is 0.4-0.5” in narrowleafed cattail and 0-2” in hybrid cattail.
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 animals, but large monospecific stands of invasive
cattails exclude other, more valuable, wildlife
food and cover species.
Fruits & seeds: Cigar-shaped, 2-6” long, with
soft, downy seeds. Produces up to 250,000 seeds
per year. Seeds remain viable in the soil for up
to 100 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.
Typha angustifolia
Typha x glauca
58
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 (1) currently less widespread in our region but highly invasive in some areas; (2) invasive in other parts of
the country and are just beginning to arrive in the Midwest; and (3) 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
59
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 2008 and maps developed for MIPN’s “Keep
60
a Lookout” flyers.
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:
1) Plant these species only next to concrete or lawns. Do not plant them next to natural areas.
2) 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, 2006
Invasive Plants: Guide to Identification and the Impacts and Control of Common North American Species by
Sylvan Ramsey Kaufman & Wallace Kaufman, Stackpole Books, 2007
Invasive Plants of the Southern Tier, USFS Region 9 by Carol Mortensen, USDA Forest Service, 2002
Invasive Plants of the Upper Midwest by Elizabeth Czarapata, Univeristy of Wisconsin Press, 2005
Manual of Vascular Plants of Northeastern United States and Adjacent Canada, Second Edition by Henry A.
Gleason and Arthur Cronquist, The New York Botanical Garden, 1991
Minnesota Invasive Non-native Terrestrial Plants: An Identification Guide for Natural Resource Managers by
the Minnesota Department of Natural Resources, 2003
61
Weeds of the North Central States, North Central Regional Research Publication No. 281, Bulletin
772, University of Illinois at Urbana-Champaign, 1981
Weeds of the Northeast by Richard Uva, Joseph C. Neal, and Joseph M. DiTomaso, Cornell University
Press, 2007
Weeds of the Northern Lakes States by Carol Estes Mortensen, USDA Forest Service, 2001
Weeds of the Northern U.S. and Canada, by France Royer & Richard Dickinson, The University of
Alberta Press & Lone Pine Publishing, 1999
Weeds 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, 1999
Websites:
Midwest Invasive Plant Network, www.mipn.org
Plant 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.edu
USDA PLANTS database, www.plants.usda.gov
Papers & reports:
Stinson, K.A., et al. 2006. Invasive plant supresses the growth of native tree seedlings by disrupting
belowground mutualisms. PLoS Biol 4(5): e140.
Pavlovic, N., et al. 2007. American and Oriental Bittersweet Identification, U.S. Geological Survey,
Great Lakes Science Center, GLSC Fact Sheet 2007-2.
Schierenbeck, K., et al. 1994. Effects of herbivory on growth and biomass allocation in native and
introduced species of Lonicera. Ecology 75 (6) 1661-1672.
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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 Agriculture (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; Russian 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 & Preserves (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 (infestation 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
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Index
Ailanthus altissima, 5-6
Alliaria petiolata, 7-8
Asian bittersweet, 13-14
autumn olive, 21-22
Berberis thunbergii, 9-10
black locust, 51-52
buckthorn, common, 49-50
buckthorn, glossy, 49-50
Canada thistle, 17-18
Carduus acanthoides, 12
Carduus nutans, 11-12
cattail, hybrid, 57-58
cattail, narrow-leaved, 57-58
Celastrus orbiculatus, 13-14
Centaurea stoebe, 15-16
Centaurea maculosa, 15-16
Cirsium arvense, 17-18
common reed, 45-46
Coronilla varia, 55-56
crown vetch, 55-56
cypress spurge, 24
dame’s rocket, 25-26
Dipsacus fullonum, 19-20
Dipsacus laciniatus, 19-20
Dipsacus sylvestris, 19-20
Elaeagnus angustifolia, 21-22
Elaeagnus umbellata, 21-22
Euphorbia cyparissias, 24
Euphorbia esula, 23-24
Eurasian watermilfoil, 39-40
Fallopia japonica, 47-48
Frangula alnus, 49-50
garlic mustard, 7-8
Hesperis matronalis, 25-26
honeysuckle, Asian bush, 31-32
honeysuckle, Japanese, 29-30
Japanese barberry, 9-10
Japanese stiltgrass, 37-38
knotweed, giant, 48
knotweed, Japanese, 47-48
leafy spurge, 23-24
Ligustrum japonicum, 28
Ligustrum obtusifolium, 27-28
Ligustrum sinense, 28
Ligustrum vulgare, 27-28
Lonicera japonica, 29-30
Lonicera maackii, 31-32
Lonicera morrowii, 31-32
Lonicera tatarica, 31-32
Lonicera x bella, 31-32
Lythrum salicaria, 33-34
Melilotus alba, 35-36
Melilotus officinalis, 35-36
Microstegium vimineum, 37-38
multiflora rose, 53-54
musk thistle, 11-12
Myriophyllum spicatum, 39-40
Nepalese browntop, 37-38
nodding thistle, 11-12
Pastinaca sativa, 41-42
Phalaris arundinacea, 43-44
Phragmites australis, 45-46
plumeless thistle, 12
Polygonum cuspidatum, 47-48
Polygonum sachalinense, 48
privet, border, 27-28
privet, common, 27-28
privet, Chinese, 28
privet, Japanese, 28
purple loosestrife, 33-34
reed canarygrass, 43-44
Rhamnus cathartica, 49-50
Rhamnus frangula, 49-50
Robinia pseudoacacia, 51-52
Rosa multiflora, 53-54
Russian olive, 21-22
Securigera varia, 55-56
spotted knapweed, 15-16
sweetclover, white, 35-36
sweetclover, yellow, 35-36
teasel, common, 19-20
teasel, cut-leaved, 19-20
tree-of-heaven, 5-6
Typha angustifolia, 57-58
Typha x glauca, 57-58
wild parsnip, 41-42
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Funding for this field guide was provided by:
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