Japanese knotweed

This species is prohibited under Michigan law; forms dense thickets that shade out natives; rhizomes can damage pavement; extremely difficult to eradicate; spread by flood waters.

Photo credit: Nisa Karimi, Wisconsin Department of Natural Resources 

Bohemian knotweed

Hybrid cross between Japanese knotweed (Polygonum cuspidatum) and Giant knotweed (Polygonum sachalinensis).

Photo credit: Robert Vidéki, Doronicum Kft.,

Giant knotweed

Hybridizes with Japanese knotweed and silver lace vine (P. baldschuanicum).

Photo credit: Leslie J. Mehrhoff, University of Connecticut,

Tree of Heaven

The tree of heaven (Ailanthus altissima) is a rapidly growing deciduous tree native to China that has become a widespread invasive species across North America.

Photo credit: The Nature Conservancy

Invasive Phragmites

This species has been listed as a restricted species under Michigan law; forms dense, impenetrable stands.

European frog-bit

This species is listed as a prohibited noxious weed by the Michigan Department of Agriculture; most plants are dioecious and many populations consist of only one sex; in mixed populations, most plants are male and little seed is produced.

Photo credit: Leslie J. Mehrhoff, University of Connecticut,


Black/pale swallow- wart

Grows rapidly over native vegetation; wind-dispersed seed travels long distances.

Photo credit: Rob Routledge, Sault College,

More information regarding these and other woody invasive species can be found at

the Woody Invasives of the Great Lakes Collaborative

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