Tree of Heaven or Ailanthus

Ailanthus altissima

Family: Simaroubaceae or Quassia

Leaves: Alternate; once pinnately compound; 1' to 2-1/2' long with 11 to 41 leaflets; deciduous; leaflets ovate- lanceolate, 3" to 6" long, entire margins except typically glandular-lobed near the base; bad smelling when crushed.

Twigs/buds: Twigs very coarse; velvety or downy; brown pith. No terminal bud; lateral buds round, brown, normally hairy, relatively small.

Flowers/fruit: Dioecious (some flowers are perfect). Flowers are yellow-green, small, 5-petals; arranged in long bunches, blooming in June; inconspicuous. Fruit a samara; oblong; spirally twisted wing in center of which is a single, dry seed; yellow-green turning orange-red in late summer and finally brown in fall; fairly attractive; normally occurs in great abundance.

Bark: Thin; gray; smooth; becomes slightly furrowed with age.

Wood: Unimportant; little information is published; light colored; brittle.

General: Native to China, but becoming naturalized in urban areas anywhere it has been planted. Starts readily from seed that is scattered by wind, and from root sprouts. Thrives under almost any type of condition, especially harsh, urban conditions. Resistant to air pollution; difficult to get rid of. Shade intolerant.

Landscape Use: A large, tough tree that sprouts readily, grows very fast, is weak-wooded, and is fairly short-lived. Common mainly in cities, where large trees will grow right out of pavement cracks and window wells. Quite attractive, but with a lot of bad habits that make it undesirable except for the worst sites. Zones 4-8.

Comments and Limitations:

• Weak wood and/or branch structure.
• Fruit and/or plant part can be nuisances; use fruitless varieties if possible.
• Sucker (sprout) growth can be a problem.
• Rarely should be planted, though limited use in specific situations may be justified.