Tree-of-heaven was first introduced to America by a gardener in Philadelphia in 1784, and by 1840 was commonly available from nurseries. The species was also brought into California mainly by the Chinese who came to California during the gold-rush in the mid-1800s. Today it is frequently found in abandoned mining sites there. The history of Ailanthus in China is as old as the written language of the country.
Ailanthus has smooth stems with pale gray bark and twigs which are light chestnut brown, especially in the dormant season. Its large compound leaves are 1-4 feet in length, alternate, and composed of 10-41 smaller leaflets. Flowers occur in large terminal clusters and are small and pale yellow to greenish. There are flat, twisted, winged fruits each containing a single central seed remaining on the tree from late summer to early fall.
Tree-of-heaven reproduces both sexually (by seeds) and asexually through vegetative sprouting. Flowering occurs late in the spring. Ailanthus is dioecious, with male and female flowers on separate plants. The fruits, or samaras, occur in terminal clusters on female plants during the summer, and may persist on the tree through the winter. 1 study reports that an individual tree can produce as many as 325,000 seeds per year. Established trees also produce numerous suckers from the roots and re sprout vigorously from cut stumps and root fragments.
Tree of Heaven is a both grows and reproduces at a fast rate allowing it to push out native species and create large thickets. It is important not to confuse native shrubs and trees with ailanthus. Native sumacs (Rhus) and trees like ash (Fraxinus), hickory (Carya), black walnut, butternut and pecan (Juglans) can be distinguished from tree-of-heaven by having completely serrated (toothed) leaf margins.
Hand pulling is acceptable for small saplings of this species, with mechanical removal and a "cut-and-dab" chemical treatment needed for larger trees. Make sure to bag all limbs that may contain seed pods to prevent the spread of the plant. Foliar spray is not recommended as it can be harmful to the surrounding flora and fauna. See the invasive removal page for how to carry out these methods. Any removal within 100 feet of wetland resource areas, including certified vernal pools, or within 200 feet of a perennial stream may require approval from the Concord Natural Resources Commission. Please contact the Division of Natural Resources before you begin.
The following native plants can serve as a good replacement to Ailanthus in a garden: