Tree of heaven (Ailanthus altissima) is a fast-growing, prolific seed producer that was listed in Minnesota as a Restricted Noxious Weed beginning in 2017. It is native to China and was brought to North America in the late 1700s as an ornamental shade tree. In urban areas, it can cause damage to sewers, pavement, and building foundations; in natural ecosystems, it can establish dense monocultures that outcompete native plants.
Tree of heaven looks similar to staghorn sumac, ash, and walnut trees. It can reach heights of 70 feet and has compound leaves that can be 1-4 feet in length with 11-41 leaflets. The flowers are small, yellowish-green, and arranged in large clusters at the ends of the leaves. It produces winged fruit similar to maple trees that hang in long clusters. The fast-growing, horizontal roots can send up new sprouts up to 90 feet from the parent stem. Tree of heaven also emits a strong, offensive odor that helps distinguish it from other plants.
Though there is only one documented tree of heaven in Minnesota, it has the potential to become invasive in the state. It is highly adaptable and tolerant of disturbance. Because of its tolerance to pollution and tight rooting spaces, it has been planted in many urban areas. Several guidelines may be used to manage and prevent it from spreading: