The tree of heaven (Ailanthus altissima) is also known as the Chinese sumac, copal-tree, stink tree, and varnish tree is a problematic exotic invasive species in Iowa. It is often confused with sumac; however the tree of heaven can be distinguished by the foul odor it emits.
Hardiness: Zones 4 through 8
Growth Rate: Fast
Mature Shape: Rounded
Height: 70-100 Feet
Width: 35-50 feet
Site Requirements: Full sun on well drained moist soil, but can survive almost anywhere
Flowering Dates: April - July
Seed Dispersal Dates: Fall - Winter
Seed Bearing Age: 2-3 years
Seed Bearing Frequency: Yearly
Seed Stratification: Prechill for 2 months at 34°F to 40°F
It is a deciduous tree that can grow 40 to 60 feet tall, maximum height of 89 feet, with a trunk diameter of 2 to 3 feet. The leaves are alternate, pinnately compound, 1 to 3 feet long, with thick smooth petioles; having 11 to 41 leaflets, each 1 to 2 inches long, ovate-lance shaped, unequal base, entire margins with teeth at the base and dark green on top and paler underneath. The fruit or seeds are winged papery samaras; red, yellow, and green, and hang in dense clusters.
In June the pistillate trees bear large clusters of seeds, and the staminate trees emit a malodorous stench. The tree of heaven grows rapidly and is very difficult to eradicate once its established – competes aggressively with more desirable native trees.
A native to China and Taiwan and naturalized in North America – commonly cultivated. Considered an invasive species along roadsides, and neglected property, especially in and around urban areas.