Invasive Plants of Midewin

Do you know that nearly one-quarter of the kinds of plants growing wild in Illinois are not native here? They come from somewhere else!


Many of the plants we grow as crops, lawn, or garden flowers originate from Europe, Asia, or other places. Common wild plants, including dandelions, Queen Anne’s lace, clover, and crabgrass were brought here from other lands. While most of these non-native plants are beneficial to us, or at least benign, some do cause problems; these are the non-native invasive plants.


Some of these plants cause obvious damage, such as the weeds that infest farmland or gardens, and some invasive plants have a more insidious impact. These plants harm our natural heritage by changing native habitats and, displacing native wildlife and plants. Invasive species (both plants and animals) are now considered the #2 threat to endangered wildlife and plants (#1 remains habitat destruction).


How did these non-native invasive plants get to Illinois?


Some were brought on purpose and planted in gardens. Gardeners and nursery growers were unaware of the threat these plants posed and the plants have spread unchecked. Purple loosestrife, bush-honeysuckle, and buckthorn all originated as garden plants. Other invasive plants were imported because of perceived benefits to wildlife or other natural resources. Autumn olive and multiflora rose were planted to provide food and cover for wild game, and crownvetch was used to control erosion. Instead, these plants now degrade habitats and displace the native plants needed by wildlife for food and cover. Invasive plants can alter wetlands by causing changes in water levels or shading out desirable vegetation. Reed canary-grass has taken over many wetlands and displaced all the native sedges, rushes, and wildflowers.


Why are these plants out of control?


These plants have been brought here from somewhere else, and they left their natural enemies (especially insects and diseases) behind. At Midewin, we attack invasive plants using many techniques. Restoring native habitats, such as tallgrass prairie, helps to provide competition for non-native plants. But for the natives to get a foothold, we often must reduce infestations by hand-pulling, mowing, cutting, cultivating, and using compatible herbicides. No one technique works 100%, and we often use a combination of the above methods.


There are nearly 70 non-native, invasive plant species at Midewin that threaten restoration, management, health, and safety.


Priority species treated in 2008, for example, include:

  • garlic mustard
  • cut-leaved teasel
  • common teasel
  • yellow sweet clover
  • white sweet clover
  • wild parsnip
  • poison hemlock
  • canada thistle
  • musk thistle
  • bull thistle
  • plumeless thistle
  • blue globe thistle
  • purple loosestrife
  • crownvetch
  • bird’s-foot trefoil
  • reed canary grass
  • common reed
  • invasive cattails
  • autumn-olive
  • osage-orange
  • multiflora rose
  • amur honeysuckle
  • white mulberry
  • black locust
  • european buckthorn
  • sericea lespedeza
  • red clover
  • white clover
  • quack-grass
  • smooth brome grass
  • field garlic