September 19, 2007
Tree-of-heaven or ailanthus (Ailanthus altissima) is a deciduous tree that grows up to 80 feet tall with long pinnately compound leaves, gray slightly fissured bark, and large terminal clusters of greenish flowers in early summer. Flowers and other parts of the plant have a strong odor. Tree-of-heaven sprouts have been found to grow 10 to 14 feet and seedlings 3 to 6 feet tall in the first year, with vigorous growth continuing for 4 or more years. Nonnative trees such as tree-of heaven hinder reforestation and management of right-of-ways and natural areas, as well as dramatically altering habitats. Read more about this plant and specific methods to control it.
Synonyms: ailanthus, Chinese sumac, stinking sumac, paradise-tree, copal-tree
Plant. Deciduous tree to 80 feet in height and 6 feet in diameter, with long pinnately compound leaves and circular glands under lobes on leaflet bases. Strong odor from flowers and other parts, sometimes likened to peanuts or cashews.
Stem. Twigs stout, chestnut brown to reddish tan, and smooth-to-velvety with light dots (lenticels) and heart-shaped leaf scars. Buds finely hairy, dome-shaped, and partially hidden by the leaf base. Branches light gray to dark gray, smooth and glossy, with raised dots becoming fissures with age. Bark light gray and rough with areas of light-tan fissures.
Leaves. Alternate, odd- or even-pinnately compound, 10 to 41 leaflets on 1- to 3-foot light-green to reddish-green stalks with swollen bases. Leaflets lanceolate and asymmetric and not always directly opposite, each 2 to 7 inches long and 1 to 2 inches wide. Long tapering tips and lobed bases with one or more glands beneath each lobe (round dots). Margins entire. Dark green with light-green veins above and whitish green beneath. Petioles 0.2 to 0.5 inch long.
Flowers. April to June. Large terminal clusters to 20 inches long of small, yellowish-green flowers, with five petals and five sepals. Male and female flower on separate trees. Fruit and seeds. July to February. Persistent clusters of wing-shaped fruit with twisted tips on female trees, 1 inch long. Single seed. Green turning to tan then brown.
Ecology. Rapid growing, forming thickets and dense stands. Both shade and flood intolerant and allelopathic. Colonizes by root sprouts and spreads by prolific wind- and water-dispersed seeds. Viable seed can be produced by 2- and 3-year-old plants.
Resembles hickories, Carya spp., and sumacs, Rhus spp., but neither has glands at leaflet bases. Hickories distinguished by a braided bark, sumacs by shrub shape.
Recommended control procedures:
Large trees. Make stem injections and then apply Garlon 3A, Pathway*, Pathfinder II, or Arsenal AC* in dilutions and cut spacings specified on the herbicide label (midsummer best, late winter somewhat less effective). For felled trees, apply these herbicides to stem and stump tops immediately after cutting.
Saplings. Apply Garlon 4 as a 20-percent solution in commercially available basal oil, diesel fuel, or kerosene (2.5 quarts per 3-gallon mix) with a penetrant (check with herbicide distributor) to young bark as a basal spray.
Seedlings and saplings. Thoroughly wet all leaves with one of the following herbicides in water with a surfactant (July to October): Arsenal AC* as a 1-percent solution (4 ounces per 3-gallon mix), Krenite S as a 30-percent solution (3 quarts per 3-gallon mix), or Garlon 4 as a 2-percent solution (8 ounces per 3-gallon mix).
* Nontarget plants may be killed or injured by root uptake.
From: Miller, James H. 2003. Nonnative invasive plants of southern forests: a field guide for identification and control. Gen. Tech. Rep. SRS-62. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 93 p.
Read more about kudzu and other invasive plants in the Spring 2005 issue of Compass magazine at http://www.srs.fs.usda.gov/compass/spring2005/