What are the different types of problem plant species and how are they defined?
Weed: The USDA-APHIS defines a weed as any plant that poses a major threat to agriculture and/or natural ecosystems within the United States. Although this is more specific than a typical dictionary definition (i.e. a plant growing in an undesired location), it more accurately portrays the economic and ecological impact weeds can cause on our landscapes and on the natural ecosystems we are recreating. It is important to realize that in restoration and enhancement work species other than those listed on the USDA-APHIS, Noxious Species List or State Lists, can (and do), limit success and must not be excluded from consideration. Alien species: A species introduced and occurring in locations beyond its known historical range. This included introductions from other continents, bioregions, and also those not native to the local geographic region. Executive Order (E.O.), Invasive Species, February 3, 1999 more narrowly defines an alien species and ties the definition to an occurrence outside
