List of invasive plant species in Wisconsin Wikipedia
This list of Invasive plants of Wisconsin includes both non-native and native aggressive species that can and often will dominate a small to large area. The dominance is such that it clearly threatens the diversity of many native ecosystems.
Common invasives include:
The Invasive Plants Association of Wisconsin (IPAW) is a primary group working to address the problems presented by these invasive species, with the Wisconsin Department of Natural Resources site being another useful source of information.