Ailanthus (Tree-of-Heaven)

Ailanthus altissima commonly known as tree of heaven, ailanthus, or in Standard Chinese as chouchun (Chinese: ����; pinyin: ch��uch��n; literally “malodorous tree”), is a deciduous tree in the Simaroubaceae family. It is native to both northeast and central China and Taiwan. Unlike other members of the genus Ailanthus, it is found in temperate climates rather than the tropics. The tree grows rapidly and is capable of reaching heights of 50 ft in 25 years. However, the species is also short lived and rarely lives more than 50 years. The tree was first brought from China to the United States in 1784. A. altissima is a medium-sized tree that reaches heights between 56 and 90 ft with a max diameter at breast height of about 40 in.

The LEAVES are large, odd or even-pinnately compound, and arranged alternately on the stem. They range in size from 1 to 3 ft in length and contain 10�C41 leaflets organized in pairs, with the largest leaves found on vigorous young sprouts. The rachis is light to reddish-green with a swollen base. The leaflets are ovate-lanceolate with entire margins, somewhat asymmetric and occasionally not directly opposite to each others. Each leaflet is 2.0 to 7.1 in long and 0.98 to 2.0 in wide. They have a long tapering end while the bases have two to four teeth, each containing one or more glands at the tip. The leaflets’ upper sides are dark green in color with light green veins, while the undersides are a more whitish green. The petioles are 0.20 to 0.47 in long. The lobed bases and glands distinguish it from similar sumac species.

The FLOWERS are small and appear in large panicles up to 20 in in length at the end of new shoots. The individual flowers are yellowish green to reddish in color, each with five petals and sepals. The sepals are cup-shaped, lobed and united while the petals are valvate (i.e. they meet at the edges without overlapping), white and hairy towards the inside. They appear around mid-April. A. altissima is dioecious, with male and female flowers being borne on different individuals. Male trees produce three to four times as many flowers as the females, making the male flowers more conspicuous. The male plants emit a foul-smelling odor while flowering to attract pollinating insects.

The SEEDS borne on the female trees are 5 mm in diameter and each is encapsulated in a samara that is 1 in long and 0.39 in broad, appearing July though August, but usually persisting on the tree until the next spring. The samara is twisted at the tips, making it spin as it falls and assisting by wind dispersal. The females can produce huge amounts of SEEDS normally around 14,000/lb of tree.

The BARK is smooth and light grey, often becoming somewhat rougher with light tan fissures as the tree ages. The TWIGS are stout, smooth to lightly pubescent, and reddish or chestnut in color. They have lenticels as well as heart-shaped leaf scars (i.e. a scar left on the twig after a leaf falls) with many bundle scars (i.e. small marks where the veins of the leaf once connected to the tree) around the edges. The BUDS are finely pubescent, dome shaped, and partially hidden behind the petiole, though they are completely visible in the dormant season at the sinuses of the leaf scars

In China, the tree of heaven has a long and rich history. It was mentioned in the oldest extant Chinese dictionary and listed in countless Chinese medical texts for its purported ability to cure ailments ranging from mental illness to baldness. The roots, leaves and bark are still used today in traditional Chinese medicine, primarily as an astringent.