Origin:
Central China
Background: Tree of Heaven is a common weedy tree growing in urban areas. This invasive was introduced to the northeastern
United States
from
Europe
(where it is also invasive) by a Pennsylvanian gardener in 1748. Tree of Heaven was widely planted in
North America
because of its resistance to pollution and poor soil conditions.
While this tree is native to
China,
it is viewed as a nuisance species there as well — an early Chinese saying calls spoiled children “good for nothing ailanthus sprouts.”
Habitat: Tree of Heaven occurs in 42
U.S.
states. It is extremely common in urban areas, especially along highways and other roads. This tree tolerates drought well but does not thrive in areas commonly flooded. Tree of Heaven is adapted to a wide variety of soil conditions including rocky areas. It is primarily an early successional species, with limited ability to compete in areas with mature trees that shade out a majority of the sunlight. Tree of Heaven can, however, take over forest ecosystems that have been disturbed by insects or other occurrences, both natural and anthropogenic.
Ecological Threat: Tree of Heaven can cause damage to sewers, foundations, sidewalks, roadways, and power lines in urban areas but poses a greater threat because of its invasiveness, particularly in agricultural fields and natural habitats. Tree of Heaven grows vigorously, produces many seeds, and can establish dense stands that displace native plants. Tree of Heaven also produces chemicals that may kill other plants or prevent them from growing, and can poison animals or small children if ingested. A study published in the American Journal of Botany details the identification of a poisonous compound in Ailanthus that has had negative impacts on native plants and animals.
Tree of Heaven has garnered attention as of late for taking over the highway borders on the
Long Island
Expressway. Ailanthus will grow anywhere—it sometimes springs up out of the cement!
Description and Biology:
Plant: Deciduous tree grows up to 80ft tall and 6ft in diameter. Twigs are brown to reddish tan, smooth with light spots called lenticels, and heart-shaped leaf scars. Buds are slightly fuzzy and dome-shaped. The branches are light gray to dark gray and are smooth and glossy. The bark is light gray and rough.
Leaves: Leaflets occur in numbers of 10 to 41, on 1 to 3 foot light green to reddish-green stalks. The leaflets are lance-shaped and asymmetrical, each is 2 to 7 inches long and 1 to 2 inches wide. The leaflets are also dark green with light green veins on the top side and whitish green on the bottom. Petioles are 0.2 to 0.5 inches long.
Flower, fruit, and seeds: Flowering occurs from April to June. Flowers are yellowish-green with five petals. Flowering occurs in large clusters up to 20 inches long. Tree of heaven is dioecious—male and female flowers occur on separate trees. Clusters of wing-shaped fruit with twisted tips occur on female trees from July to February. Single seeds are green, eventually turning brown.
Reproduction: Tree of Heaven reproduces from both seed and root sprouts. A high percentage of seeds are viable and are primarily distributed by the wind.
Identification: Tree of Heaven may be confused with other trees having compound leaves and many leaflets. Black walnut (Juglans nigra), butternut (Juglans cinerea), and some species of sumac (Rhus spp.) fit this description. The leaf margins of the look-alikes have small teeth, with the exception of winged sumac, while those of Tree of Heaven are smooth. Tree of Heaven also possesses a characteristic odor that can be produced by scraping its bark or crushing its foliage. The odor is sometimes compared to the odor of peanuts or cashews.
Prevention & Control:
Hand Pulling: Young Tree of Heaven seedlings can be removed by hand. The plants must be pulled as soon as they are large enough to grasp, before they produce seeds. The best time to pull is after a rain because the water loosens the soil. It is critical that the entire root is removed—broken fragments may resprout.
Cutting: Trees should be cut at ground level with a power or manual saw. This method is most effective when the tree has begun to flower. This prevents seed production. Resprouts may occur after treatment and successful control will require repeated cutting.
Girdling: This method can be used on very large trees. A cut through the bark encircling the base of the tree should be made with an axe, approximately 6 inches off the ground. The cut should be made well into the cambium layer; past the bark of the tree, extending into the woody, ringed part of the tree. This method works by killing the top of the tree. As with the cutting method, resprouting may occur, and follow-up treatments must be made for several years until the roots are exhausted.
Native Alternatives:
Smooth Sumac (Rhus glabra)
Staghorn Sumac (Rhus typhina)
