Alternate name: Tree-of-heaven
Family: Simaroubaceae, Quassia view all from this family
Description A hardy, introduced tree with a spreading, rounded, open crown of stout branches and coarse foliage; male flowers and crushed leaves have disagreeable odor.
Height: 50-80' (15-24 m).
Diameter: 1-2' (0.3-0.6 m).
Leaves: pinnately compound; 12-24" (30-61 cm) long. 13-25 leaflets (sometimes more) 3-5" (7.5-13 cm) long, 1-2" (2.5-5 cm) wide; paired (except at end), broadly lance-shaped, with 2-5 teeth near broad 1-sided base and gland-dot beneath each tooth; covered with fine hairs when young. Green above, paler beneath.
Bark: light brown, smooth, becoming rough and fissured.
Twigs: light brown, very stout, covered with fine hairs when young; with brown pith.
Flowers: 1/4" (6 mm) long; with 5 yellowish-green petals; in termina,l branched clusters 6-10" (15-25 cm) long; male and female usually on separate trees; in late spring and early summer.
Fruit: 1 1/2" (4 cm) long; showy, reddish-green or reddish-brown key, narrow, flat, winged, 1-seeded; 1-6 from a flower; maturing in late summer and autumn.
Warning Parts of this plant, particularly the roots, are toxic if ingested. Leaves can cause skin irritation. Sensitivity to a toxin varies with a person’s age, weight, physical condition, and individual susceptibility. Children are most vulnerable because of their curiosity and small size. Toxicity can vary in a plant according to season, the plant’s different parts, and its stage of growth; and plants can absorb toxic substances, such as herbicides, pesticides, and pollutants from the water, air, and soil.
Habitat Widespread in waste places, roadsides, old fields, and other disturbed habitats, spreading rapidly by suckers.
Range Native of China but widely naturalized across temperate North America; from near sea level to high mountains.
Discussion Ailanthus is widely planted as an ornamental for shade and in shelterbelts for its rapid growth and coarse foliage reminiscent of tropical trees. However, it is now widely considered an invasive alien and is no longer recommended for planting. Male flowers have an objectionable odor, and some people are allergic to their pollen, which may produce symptoms of hayfever. The roots, which are considered poisonous, get into drains, springs, and wells. Additionally, the toxins are thought to infiltrate the soil and prohibit growth of other, native flora. The weak branches are easily broken by storms. Tolerant of crowded dusty cities and smoky factory districts, plants often even grow out of cracks in concrete.
