Tree of Heaven (Ailanthus altissima)

Description

Tree-of-heaven is a rapidly growing deciduous tree with compound, alternate leaves up to four feet long that are composed of 11-25 opposite leaflets with one to several glandular teeth near the base. The bark is pale gray and smooth. The wood is white to light brown, soft, and coarse. Female and male flowers grow on separate trees. Clusters of small, yellowish green flowers with 5-6 petals grow close to the branch tip in late spring. Broken leaves and male flowers produce a pungent odor resembling cashews. Female flowers produce tan to pink fruits that resemble flat, twisted wings called samaras. Large clusters of samaras appear from September to October, and may remain throughout the winter.

Look-alikes

Native shrub sumacs (Rhus typhina and R. glabra), the ash (Fraxinus species), and black walnut (Juglans nigra) trees have compound leaves. However, sumac leaflets have toothed margins, and the fruits are fuzzy, red, and erect. Ashes have opposite leaves. Black walnut has toothed leaves, large green fruits, and a distinct walnut color and smell.

Impacts & Habitat

Tree of Heaven is spreading rapidly in forested areas in the eastern U.S. where it impacts all plants, from the canopy trees to the ground. It is currently found in disturbed urban areas in southern Wisconsin, but it is uncertain if it will invade forests in Wisconsin. This tree grows quickly, forming dense thickets that overtake native vegetation, and it damages sewers and foundations with its aggressive root system. It also produces a toxin that can impede the growth of other plants. One tree can grow numerous root suckers, resprout vigorously from cut stumps and root fragments, and produce up to 350,000 seeds a year with a high germination rate. Seedlings develop a taproot within three months of germination.

Control

Remove young seedlings and their roots by hand when the soil is moist. Repeatedly cut small infestations, resprouts, and large trees for several summers to reduce seed spread and exhaust the root reserves. There are several treatments for large stands: apply basal bark treatment of oil-soluble triclopyr; spray with triclopyr in the late winter, early spring, or summer; or both. To prevent stump sprouts, treat cut stumps immediately with a mixture of triclopyr or glyphosate and oil dilutent. Large stands of seedlings can be sprayed foliarly. Treat all infestations as needed and recheck several times a year.

Additional Information (Links exit DNR)

UW-Madison Herbarium
USDA
The Nature Conservancy
Plant Conservation Alliance