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An invasive plant grows quickly and aggressively forces other plants out
as it spreads. They are usually not native to North America. Most
non-native plants cause little trouble, but a few species are responsible
for degrading and destroying thousands of acres of our natural plant
communities in Indiana. This ends up costing thousands of dollars each
year to eradicate these species and protect our natural resources. These
invasives hurt our wildlife, too, by eliminating the plants our native
animals need for food and cover. Some of these invasive plants are still
being sold by nurseries and planted by well-meaning Hoosiers, not
realizing the problems they can cause. There is a bright side to this
problem. There are many non-invasive, native alternatives that could be
planted instead of the problem plants.
The following are ten of the most damaging of the many invasive plants
in Indiana. Planting alternatives are also listed.
For additional information and photos, visit
http://extension.entm.purdue.edu/CAPS/index.html
1. Bush Honeysuckles: The problem with these
6-15 foot tall shrubs is that they grow so densely, they shade out
everything on the forest floor, leaving nothing but bare dirt. This means
a great reduction in the food and cover available for birds and other
animals. Some species release chemicals into the soil to inhibit other
plant growth, effectively poisoning the soil. Alternatives: Dogwoods,
Chokeberry, Winterberry, and Northern arrowwood.
2. Purple Loosestrife: This purple-flowered
plant invades wetlands in northern Indiana and chokes out native
vegetation. Alternatives: Dense blazing-star, Wild bergamot, Cardinal
flower and Sweet joe-pye-weed.
3. Japanese Honeysuckle: The
semi-evergreen vine climbs over vegetation in southern Indiana,
forming dense patches that can overtop young forests. Alternatives:
Virginia creeper, Virgin's bower and American bittersweet.
4. Reed Canary Grass: Widely planted for
forage and erosion control, this 2-5 foot tall grass has taken over large
areas of both open and forested wetlands throughout Indiana. Alternatives: Switchgrass, Canada bluejoint, Prairie cord grass, Indian grass and Big
bluestem.
5. Autumn Olive: Often planted for
wildlife food and cover in the past, Autumn Olive is a fast-growing shrub
or small tree reaching up to 20 feet tall. It produces large quantities of
small, round red fruits that are readily eaten and spread by birds.
Alternatives: Blackhaw, Dogwoods and Serviceberry.
6. Common Reed or Phragmites: This
grass, which can reach up to 15 feet in height grows in open wetland
habitats and ditches primarily in northern Indiana. It forms huge colonies
by sprouting new shoots through underground stems. It can create pure,
impenetrable stands, excluding all other wetland plants. Alternatives:
Switchgrass, Canada bluejoint, Prairie cord grass, Indian grass,
and Big bluestem.
7. Crown Vetch: This perennial legume
has creeping stems which form dense mounds of vegetation. Introduced to
the United States for erosion control, it was very widely planted along
roadsides in Indiana. Since it has a tap root instead of fibrous roots, it
actually provides little erosion control. It invades many of our open
natural areas like prairies and savannas. Alternatives: Roundheaded
bushclover, Purple vetch and Goat's-rue. For erosion control, use a mix of
native grasses with these species.
8. Oriental Bittersweet: Overrunning
natural vegetation and weakening mature trees by girdling the trunk and
weighting the crown are just two of the problems this rapidly spreading
deciduous, twining vine can cause. Alternatives: American bittersweet,
Virgin's bower and Virginia creeper.
9. Garlic Mustard: Growing in dense
stands covering many acres of forest understory, this biennial herb is a
particular threat to spring wildflowers, overtopping and shading them out.
Compared to the diversity of plants, it eliminates, it provides little
food for wildlife. It begins, the first year, as a rosette of
kidney-shaped, garlic-smelling leaves. The second-year plants grow a stem
up to 4 feet tall. Garlic mustard can produce several thousand seeds from
one plant. Alternatives: Celandine poppy, Blue phlox and Jacob's ladder.
10. Buckthorns: Glossy and Common Buckthorn
occur in a wide variety of habitats in northern Indiana and spread quickly
through natural areas by seed. They are tall shrubs or small trees that
grow up to 20 feet tall. Buckthorns take over the understory and eliminate
the diversity of native plants important to wildlife. Alternatives:
Lance-leaved buckthorn, Carolina buckthorn, Serviceberry and Dogwoods.
This information was gathered from brochures provided by the Indiana
Native Plant and Wildflower Society (INPAWS). For more information on
native and invasive plants, please visit their website:
www.inpaws.org. Other organizations
with helpful information include the IDNR Division of Nature
Preserves, and the Native Plant
Conservation Initiative. |
