Tree-of-Heaven Ailanthus altissima By Amy L. Nash

Ailanthus altissima, also known as the Tree-of-Heaven, is member of the tropical quassia family (Simaroubaceae). This deciduous tree was first imported from China and arrived in the United States in 1784. The Tree-of-Heaven served as an ornamental tree and was popular during the Industrial Revolution because of its resistance to polluted air. During the twentieth century the species was suggested as a street tree in northeastern cities. Today the Tree-of-Heaven is widely distributed throughout the United States. It is a common tree in disturbed urban areas, where it shades alleys, sidewalks, parking lots, and streets. Outside the cities, the Tree-of-Heaven is often seen in fields, along roadsides, fencerows, woodland edges, and forest openings.

The Tree-of-Heaven received its name because of its great height; a mature tree can grow up to 80 feet or more in height. This ornamental shade tree grows very quickly under circumstances where other trees will not grow. The species does not have insect or disease problems and tolerates city conditions and almost any soil. It is resistant and grows rapidly in warm and moderately cold climates. In addition, the Tree-of-Heaven can grow close to salt at the seashore or near salted roads in the north.

The Tree-of-Heaven has smooth stems with pale gray bark and light chestnut brown twigs. The leaves are large, coarse, and compound with approximately thirteen to twenty-five leaflets. The leaflets alternate along the stalks, each leaflet has one to several glandular teeth near the base. Seeds are produced on female trees in late summer to early fall. The seeds appear in flat, twisted, papery structures known as samaras. The wood is soft, weak, coarse-grained, and creamy white to light brown in color. Sometimes the wood of the Tree-of-Heaven is used for cabinetmaking and for the manufacture of charcoal.

Reproduction of the Tree-of-Heaven occurs both sexually and asexually. Flowering often occurs late in the spring; male and female flowering takes place on separate trees. The male flowers produce a strong odor, which is often compared to burnt peanut butter. The fruits are dull yellow to bright red on individual female trees and ornamental in late summer and early autumn. An individual tree can produce as many as 325,000 seeds per year.

Several problems result because of certain characteristics of the Tree-of-Heaven. The species is an abundant seed producer and grows extremely rapidly under almost any condition. When both female and male trees are present, seedlings will germinate and grow in any available space. This tree produces considerable foliage and twig litter and can easily overrun native vegetation. Additionally, the root system of the Tree-of-Heaven is aggressive enough to cause damage to sewers and foundations.

Many management approaches have been taken to try to control the growth of the Tree-of-Heaven population. These efforts require great amount of diligence because of the species abundant seed production, high seed germination rate, and foliage production. In order to help reduce the spread of the Tree-of-Heaven by seed, it is important to target large female trees. Often cutting alone is perceived as being counter-productive because the tree reacts by producing large numbers of stump sprouts and root suckers. The most effective method to control the Tree-of-Heaven today is through the use of herbicides. In addition, it is vital that the root system be killed or seriously damaged to prevent or limit additional stump spouting and root suckering.

Although the Tree-of-Heaven is often perceived as a pest because of its ecological threat, the tree plays a famous role in Betty Smith’s 1945 classic titled "A Tree Grows in Brooklyn." The tree is used as a metaphor to represent the arrival of the immigrant class during the early twentieth century.

Written fall 2000, as a service learning project for Dr. Gary Coté's Biology 102 class at Radford University. Copyright Pathways for Radford.