Plants introduced by human activities to areas where they do not naturally occur are termed "non-native" species. When a non-native plant escapes from where it was planted and invades native plant communities, it is termed "invasive."
Invasive non-native plants displace native plants and can reduce the ability of the plant community to support native fish and wildlife, protect the soil, and filter pollutants from soil and water.
When these plants were first introduced to an area, no one knew that they would become invasive or undesirable. It was only after several years (in some cases, decades), that the extent of the damage was realized.
Some plants in this section are regulated under state law as noxious weeds or prohibited exotic species and are identified as such. Others continue to be sold because of their horticultural value in gardening and landscaping.
The DNR discourages use of the following plants. They are likely to spread and displace native species.
Trees and Shrubs
- Amur maple (Acer ginnala)
- Black locust (Robinia pseudocacia)
- Buckthorns (Rhamnus cathartica & Frangula alnus)
- Exotic honeysuckles (Lonicera tartarica, L. morrowii, L. x bella)
- Japanese barberry (Berberis thunbergii)
- Norway maple (Acer platanoides)
- Russian olive (Elaeagnus angustifolia)
- Siberian elm (Ulmus pumila)
- Siberian peashrub (Caragana arborescens)
Grasses and Wildflowers
- Amur silver grass (Miscanthus sacchariflorus)
- Bird's-foot trefoil (Lotus corniculatus)
- Bull thistle (Cirsium vulgare)
- Butter and eggs (Linaria vulgaris)
- Canada thistle (Cirsium arvense)
- Cow vetch & hairy vetch (Vicia cracca & V. villosa)
- Creeping Charlie (Glechoma hederacea)
- Crown vetch or axseed(Coronilla varia)
- Flowering rush (Butomus umbellatus)
- Garlic mustard (Alliaria petiolata)
- Grecian foxglove (Digitalis lanata)
- Hoary alyssum (Berteroa incana)
- Japanese knotweed (Polygonum cuspidatum)
- Leafy spurge (Euphorbia virgata)
- Musk or nodding thistle (Carduus nutans)
- Non-native waterlilies (Nymphaea spp.)
- Ox-eye daisy (Chrysanthemum leucanthemum)
- Perennial sow thistle (Sonchus arvensis)
- Purple loosestrife (Lythrum salicaria)
- Queen Anne's lace (Daucus carota)
- Reed canary grass (Phalaris arundinacea)
- Smooth brome grass (Bromus inermis)
- Spotted knapweed (Centaurea maculosa)
- White and yellow sweetclover (Melilotus alba & M. officinalis)
- Wild parsnip (Pastinaca sativa)
- Yellow iris (Iris pseudacorus)