Ailanthus (Ailanthus altissima)

Ailanthus (Ailanthus altissima (Mill.) Swingle), commonly called tree of heaven, is a deciduous tree that originated in Asia and is identified as a widespread nonnative invasive species in North America. Its current range in eastern North America extends from Vermont and southern Ontario to Georgia, in the U.S. Midwest from Wisconsin to southern Texas, and in western North America from southern British Columbia as far south as southern California. Ailanthus is most closely associated with urban and disturbed, open natural areas in its invasive range; it can also be found in closed canopy forests. It is intolerant of extreme cold conditions, preferring temperate, Mediterranean, and subtropical conditions. Ailanthus is tolerant of xeric conditions and low soil fertility. Ailanthus seedlings under high-light conditions can grow 1 to 2 m (3.2 to 6.6 feet) in height in a single year. After 20 years, however, growth rates tend to decrease. Herbicide application is an effective way to remove ailanthus trees of any size, but killing the root system is essential to reduce sprouting and suckering. Ailanthus abundance may increase after hurricanes, tornadoes, or windstorms, potentially displacing existing native trees. Originally imported to the United States for use in urban environments because of its tolerance to pollution, poor soil, and aridity, ailanthus is now discouraged from being planted in many U.S. and Canadian cities.