(The following information is supplied courtesy of the Nature Conservancy) What are invasive species? Species become invasive when they are introduced to an area outside their native range and are free from natural competitors and predators, allowing them to proliferate and persist to the detriment of native species. Why are invasive plants a problem? Invasive plants can cause widespread harm by out-competing native plants, increasing erosion along stream banks, clogging streams and waterways, and providing less nutritious food and insufficient cover for wildlife. Because invasive species are free of natural restraints they are able to quickly establish themselves in new areas, to grow and spread rapidly, and to choke out native species. What are the top invading plant species in Vermont?* Asiatic bittersweet (Celastrus orbiculatus) Buckthorn (Rhamnus spp.) Bush honeysuckles (Lonicera spp.) Burning bush (Euonymus alatus) Common reed (Phragmites australis) Japanese barberry (Berberis thunbergii) Knotweed (Polygonum cuspidatum) Garlic mustard (Alliaria petiolata) Goutweed (Aegopodium podagraria) Purple loosestrife (Lythrum salicaria) Norway maple (Acer platanoides) Wild chervil (Anthriscus sylvestris) Yellow-flag iris (Iris pseudacorus) * Links are to PDF documents that range from 279-1,041 KB in size. For the names of the other invaders, download this PDF of the common invasive plant species in Vermont.