Invasive terrestrial plants are disrupting North America’s ecosystems by outcompeting native species such as milkweed, trillium, and native grasses. This competition reduces biodiversity and negatively impacts pollinators and wildlife. Additionally, these invasive or noxious species threaten agriculture, forestry, and water systems, and can also pose human health risks, such as burns from Wild Parsnip and blisters from Giant Hogweed.
North America hosts thousands of alien vascular plant species, with roughly 3,800 non-native vascular plants recorded in the U.S. (including about 1,000 invasive species) and 1,229 in Canada, of which 486 are considered invasive or weedy, especially established in disturbed areas such as roadsides, trails, and waterways.