How to Identify Tree-of-Heaven

Tree-of-Heaven, an Invasive Tree Species

Tree-of-heaven (Ailanthus altissima) is an invasive tree. It spreads quickly and is difficult to control. Tree-of-heaven grows in harsh conditions such as the building foundation shown in the photo above.

Tree-of-heaven spreads by seeds and roots. It grows an extensive root system. New shoots emerge far away from the trunk of established trees.

It forms dense thickets that displaces native vegetation.

Tree-of-heaven also grows as large trees with one or more main stems.

Large Compound Leaves

Source

Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Tree-of-heaven has large, compound leaves that grow one to three feet long as shown in the photo. The leaflets are arranged opposite each other along the central leaf stem.

When crushed, tree-of-heaven leaves smell like rancid peanut butter.

Textured, Light-colored Bark

The bark of mature tree-of-heaven main stems is textured with gray and brown colors.

The bark of young tree-of-heaven stems is smoother compared (shown in second photo) to the textured bark of older trees.

Source

https://www.forestryimages.org/browse/detail.cfm?imgnum=5576162

Seed Pods

Established tree-of-heaven trees produce hundreds of thousands of seeds each year. The seeds form in clusters of samaras (seed pods shaped like a wing) as shown in the photo.

The photo also shows the notched base on tree-of-heaven leaflets. This trait is useful for telling tree-of-heaven apart from look-alike trees.

Look-Alikes

Black walnut (Juglans nigra) also has large, compound leaves. Its leaves have a rounded base on each leaflet. When crushed, black walnut leaves have a distinct walnut family smell. Use gloves to avoid skin contact with black walnut sap.

Sumac (Rhus spp.) also has large compound leaves. It's leaves also have a rounded base on each leaflet. Many sumac varieties have serrated (jagged) leaf edges.

Tree-of-Heaven in Portland

Tree-of-heaven is on Portland's Nuisance Plant List. The plants identified on this list can't be planted in certain zones or be planted as a street tree.

For More Information

See the resources below for more information about identifying tree-of-heaven. The resources also have information about how to control it.

Tree-of-Heaven (Oregon State University)

Tree-of-Heaven (Washington State Noxious Weed Board)

Tree-of-Heaven (PennState University)