Ailanthus altissima (Mill.) Swingle (Simaroubaceae, tree-of-heaven) is native to northern China where it has a long history of association with human habitation and disturbance (Whitney and Adams 1980). It was introduced from China to Paris between 1740 and 1750 (Hu 1979). It was introduced into the United States on an extensive scale in 1820 (Dame and Brooks 1972) as an ornamental shade tree recognized for its rapid growth, luxuriant compound leaves, and ability to tolerate the stresses of urban areas (Hough 1960, Dirr 1983). It is now naturalized throughout the eastern United States, growing from Massachusetts and Ontario south, and also occurs to a lesser extent from the southern Rocky Mountains to California (Elias 1980).