Issue 3, May 19, 2014

Illinois Invasive Plant Phenology Report

Several invasive plant experts from around the state have started a new series or reports focusing on the phenology of invasive plants in Illinois. The intent of these reports is to provide an update on the development of invasive plants across the state of Illinois – what plants are in bloom, leafing out, setting seed, or senescing in different areas of the state.

Readers are encouraged to share what they see in their area of the state by emailing Chris Evans, Invasive Species Campaign Coordinator of the Illinois Wildlife Action Plan (

Phenology Report for May 16, 2014

(Contributors include Cathy McGlynn, Karla Gage, Marilyn Leger, Jody Shimp, and Mike Daab)

Southern Illinois

  • Princesstree, Paulownia tomentosa – Is in full bloom right now. Mature trees are easily identified by the dense purple flowers. Keep an eye out for this species on rocky bluffs, ridge top, barrens, and other dry disturbed sites.
  • Garlic mustard, Alliaria petiolata – Is in full seed development right now. You could still find some flowers on this species right now, but the majority of the plants have green seed pods. These seed pods are long, thin and are upright on the plant. The seed pods have not yet dried, so pulling and bagging the plants is still an option for control. Look for garlic mustard in wooded areas across the region.
  • Black locust, Robinia pseudoacacia – Is just past full bloom right now. You can still identify this tree species by its dropping clusters of white flowers, but it is starting to be past bloom. Some of the trees will have flowers that are starting to yellow or be obscured by emerging leaves
  • Chinese yam, Dioscorea oppositifolia – Is emerging now and starting to elongate. With the onset of warmer weather, this species is now starting to put on a lot of growth. Vines can be found easily now with multiple leaves. The heart to fiddle shaped leaves can be easily identified by the purple-red coloration where the petiole meets the leaf. This plant has not yet started to produce its bulbils (asexual reproductive structures) and likely won’t for a month or so. Look for Chinese yam along streamsides, ditches, and other mesic-to-wet forest sites or areas with disturbance.
  • Japanese stiltgrass, Microstegium vimineum – Is germinating right now. You can easily find young, single-lead germinates of stiltgrass carpeting the forest floor in invaded areas. This germination will continue for a while, so control treatments that do not include a pre-emergent herbicide should be delayed for another month or so.
  • Bush honeysuckle, Lonicera maackii – Is just coming into bloom right now. In a week or two this species will be in full bloom. The fragrant white flowers turn yellow with age and can be found in pairs along the stems of mature bush honeysuckle shrubs. This plant can grow in most area wooded environment.
  • Winged burning bush, Euonymus alatus - Has flowered and fruits are just beginning to form.
  • Chinese privet, Ligustrum sinense - Flowers are beginning to form but have not opened yet.

Central Illinois

Northern Illinois

Eric Smith reports from SouthCentral Illinois that Dames Rocket is starting to bloom and Oriental bittersweet is starting to bud
Jim Alwill reports from NorthWest Illinois that IDOT is starting to spray teasel rosettes along the ROWs

Follow the Illinois Invasive Species Awareness blog for more phenology reports as well as other invasive species news! (Kelly Estes)

Kelly Estes

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