Nine Plants Now Banned As Illinois Expands Exotic Weeds List Amid Invasive Species Surge

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The State of Illinois is tightening its grip on exotic weeds that have proven a menace in many habitats.

Callery pear tree is one of the newly listed exotic weeds in Illinois

With the addition of nine more invasive species to the state’s list of exotic weeds, gardeners, landscapers, and nature lovers may have found an extra line of defence.

Invasive species are non-native plants that spread quickly, threatening native vegetation, agriculture, and natural habitats. 

The List of the Newly Added Exotic Weeds

The nine listed plant species are now illegal to sell, buy, distribute, or plant across the state. They are:

  1. Callery Pear (Pyrus calleryna)
  2. Garlic Mustard (Alliaria petiolata)
  3. Tree of Heaven (Ailanthus altissima)
  4. Leafy Spurge (Euphorbia virgata)
  5. Sericea lespedeza (Lespedeza cuneata)
  6. Japanese Stiltgrass (Microstegium vimineum)
  7. Black Swallowwort (Vincetoxicum nigrum)
  8. Pale Swallowwort (Vincetoxicum rossicum)
  9. Amur Corktree (Phellodendron amurense)

Eight of the newly listed weeds — Garlic Mustard, Tree of Heaven, Leafy Spurge, Sericea lespedeza, Japanese Stiltgrass, Black Swallowwort, Pale Swallowwort, and Amur Corktree — have been updated with immediate effect under the Illinois Exotic Weeds Act (525 ILCS 10). 

The Callery Pear Tree is set to be updated on January 1, 2028, allowing growers to phase out their current stock of planted pear trees.  

“The recent changes to the Illinois Exotic Weed Act allow IDNR to more easily add species that are harmful to our natural areas and wildlife.

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This will be an important tool to help stop the spread of new invasive plants,’’ said IDNR plant ecologist Phil Cox.

“It is important to recognize these species are harmful to Illinois and take steps to reduce their impact,” added Chris Evans, an Extension forestry and research specialist, also serving on the Illinois Invasive Species Council.   

Leafy Spurge is highly invasive and difficult to eradicate
Leafy Spurge is highly invasive and difficult to eradicate. Image: Flickr/wfdetector

The invasive species are recommended for listing following extensive consultations among the council, state, and local governments, research institutions, and other stakeholders. 

The addition of the nine plant species now brings the total list to 34 invasive exotic weeds, excluding the Callery Pear Trees. 

However, the act does not regulate their current possession or require the removal of these plants. Additionally, the weeds can continue to spread naturally.