By: Debbie Nelson Master Gardener 07/01/2010
Plants that have been moved by human activity to an area where they do not normally grow are referred to as "non-native" or "exotic" plants. Not all non-natives are bad but when they cause ecological or economic problems they are termed invasive or exotic species. Common buckthorn (Rhamnus cathartica), burning bush (Euonymus alatus), Norway maple (Acer platanoides), amur maple (Acer ginnala), Japanese barberry (Berberis thunbergii), butterfly bush (Buddleia davidii) and common tansy (Tanacetum vulgare) are examples of plants released by the horticulture industry as ornamental plants that have escaped from controlled cultivation and now survive as invasive species. You might be surprised to find some of these on the list of invasive species, but one you should be very familiar with is buckthorn and that is because in 1999 it was declared a noxious weed by the state of Minnesota.