Tree-of-Heaven

Ailanthus altissima

INVASIVE SPECIES

Recognized by the large compound leaves with opposite and sub-opposite leaflets, the lower most leaflets toothed near the base with a flat, circular gland on the lower surface.

The tree was initially valued as a unique, fast-growing ornamental shade tree with the ability to grow on a wide range of site conditions, tolerating poor soils and air quality. It was widely planted from New York City to Washington, D.C. By the early 1900s the tree began losing popularity due to its "weedy" nature, prolific root sprouting, and foul odor. Tree-of-heaven has spread and become a common invasive plant in urban, agricultural, and forested areas.

Increasingly, Pennsylvania's forests are experiencing threats from invasive insect and plant species. Right now, one insect and one tree species, which maybe inextricably linked, are in the news. They are the spotted lanternfly, which was accidentally introduced to the United States in Pennsylvania in 2014, and the tree-of-heaven (Ailanthus altissima), purposely introduced to the United States and Pennsylvania in 1784. How do these two species relate?

First, if you have not heard of the spotted lanternfly, you will. In just four years, this insect from China has rapidly spread, and is found in 13 southeastern Pennsylvania counties, which are now under quarantine. The spotted lanternfly is threatening fruit and grape production (think about Pennsylvania's burgeoning wine industry) and at least 25 forest tree species. To learn more about the spotted lanternfly, start your web search at Penn State Extension's website. This insect is a major threat and worthy of everyone's attention.

Tree-of-heaven is also native to China. For years, foresters and woodland owners across Pennsylvania and the east have worried about how this invasive tree species can and will affect forests. It is a rather aggressive invasive species that shows up in unexpected places. It is especially well suited to urban environments and does well on disturbed sites such as those found along transportation rights of ways. It can even take advantages of cracks in sidewalks. You may have heard of it as "A Tree Grows in Brooklyn." This is the same tree.

So, both the spotted lanternfly and tree-of-heaven are from China. Why is this important? The science is still unfolding. While it seems that the spotted lanternfly can reproduce on many trees and shrubs, it does seem to show a distinct preference for tree-of-heaven. However, researchers are working on this question. Importantly, though, controlling tree-of-heaven could play a role in slowing the lanternfly's advance. Therefore, learning to identify tree-of-heaven is the first step in managing the pest's spread.