Tree of Heaven - Ailanthus altissima
The Tree of Heaven (Ailanthus altissima) is a fast-growing, highly invasive tree that has become a growing concern across many parts of North America, including British Columbia. Originally native to China and Taiwan, it was introduced for ornamental planting because of its fast growth, drought tolerance, and ability to survive poor soil and polluted urban conditions. Unfortunately, those same traits make it very difficult to manage once its established.
It can be confused with Black Walnut, Ash or Staghorn Sumac trees, but its large compound leaves, smooth edged leaflets with small lobes at the base, and thing grey-brown bark helps set it apart. Another easy way to identify the Tree of Heaven is the smell. Crushing any part of the tree can release a strong, unpleasant odor, sometimes compared to rancid peanuts. The tree is dioecious, meaning individual trees are either male or female, and female trees can produce up to 325,000 seeds per year, primarily spread by wind.
Beyond prolific seed production, the Tree of Heaven spreads aggressively though root suckering and fragments, allowing it to quickly colonize disturbed areas like forest edges, roadsides, railways, riverbanks, and urban lots. It is shade-intolerant, but thrives where native plants often struggle, outcompeting surrounding vegetation for water, nutrients and space. It’s also an alleopathic tree, meaning it releases chemicals into the soil that hinders the growth of other plant species, further reducing native plant growth.
Management can be challenging. Pulling or digging young saplings can be effective if the entire root system is removed, but cutting alone is rarely successful due to the trees strong suckering response. Repeated cutting way weaken the tree over time, but larger infestations often require a multi-step approach that includes targeted herbicide application late in the growing season, when the tree is moving carbohydrates to its roots. All plant material should be bagged and disposed of properly to prevent spread, and tools and equipment should be cleaned after working in infested areas.
Because of its aggressive nature and potential impacts on ecosystems, infrastructure, and even human health (pollen allergies and skin irritation), the Tree of Heaven is not recommended for ornamental planting. If you suspect it on your property, especially a large infestation, consulting a qualified arborist can help ensure effective, responsible management and reduce the risk of reinfestation.
