Tree of Heaven (Ailanthus altissima), also called Stinking Sumac, Chinese Sumac, or Tree of Hell, is one of the most prolific and hard-to-eradicate of California's many invasive weeds. It is a member of the simarouba family, which is closely related to the cashew family, which helps explain why all parts of this tree smell something like rotting cashew nuts or rancid cashew butter. The cashew family contains Chinese Pistache trees, pepper trees, sumac, and Poison Oak. The simarouba family is also closely related to the soapberry family, which contains maple trees, buckeye trees, and goldenrain trees; to the citrus family, which contains orange trees, lemon trees, lime trees, tangerine trees, pomelo trees, grapefruit trees, and kumquat trees; and to the chinaberry family.
Tree of Heaven is a fast-growing deciduous tree from Asia that spreads by seeds and root suckers. It usually grows 60 to 90 feet tall. It can grow 50 feet tall in 25 years but rarely lives longer than 50 years. However, its root suckers survive to produce numerous new trees. Where you see a Tree of Heaven, you'll usually see a cluster of many Trees of Heaven. These trees are usually either male or female but sometimes bear male and female flowers on the same plant; occasionally they even bear flowers that contain both male and female parts in the same flower. Only flowers with male parts produce pollen, but female trees may not be reliably exclusively female. The male trees are ranked 9 out of 10 on the Ogren Plant Allergy Scale, indicating that they tend to cause severe hay fever.
Tree of Heaven is also a preferred host for an invasive insect pest, the spotted lanternfly.
U.C. Davis provides advice on how to eradicate Tree of Heaven.
The City of Woodland is knowingly and intentionally growing Tree of Heaven at City Hall and Woodland Public Library and also as street trees on 3rd Street, Dog Gone Alley, and Oak Avenue. In fact, the Urban Forest Resource Analysis published by the City of Woodland in 2018 indicated that the city was knowingly and intentionally maintaining 16 of these invasive weeds in Woodland.
Links
California Invasive Plant Council: Ailanthus altissima
