I Spy in the Sea to Sky…

I Spy in the Sea to Sky…
I Spy in the Sea to Sky…

My name brings to mind a lofty aspiration,

But my growth habits point more to damnation.

I grow anywhere and everywhere, even in a gutter,

If you crush my leaves they smell of peanut butter!

Photo credit: R. Armbrust, Kansas Forest Service, Bugwood.org

Tree of Heaven, despite its name, is not a species that one would typically think of as ‘heavenly’. Not only does this tree grow very fast (1-2m per year!) and spread prolifically, but it also hosts another invasive species, the Spotted Lanternfly. Tree of Heaven supports this pesky insect’s entire life cycle while it feeds excessively on other nearby plants.

Tree of Heaven is native to China, having been brought to North America as an ornamental plant that quickly spread out of control. This species is, unfortunately, still commonly sold at garden centres. Tree of Heaven is tolerant of air pollution, poor, compacted soils, and wind, making it well adapted to grow in urban areas. It can be spotted growing in various environments, including through cracks in roads and sidewalks. It is, however, intolerant of full shade and flooding.

Photo credit: iancruickshank, iNaturalist

Tree of Heaven is typically a small tree but can grow up to 30 m tall with a trunk 2 m wide. These trees typically live between 30 and 50 years but have been known to live as long as 100 years. The bark on young trees begins as gray-brown and smooth, becoming rougher as the tree matures. Their leaves are made up of oval, smooth-edged leaflets with pointed tips, and the whole leaf unit reaches 0.5 – 1 m long. When crushed, the leaves give off an odour similar to peanut butter or burnt rubber. New shoots are yellow- to reddish-brown. Its cone-shaped clusters of yellow or white tiny flowers eventually mature, producing showy, red, winged seeds (similar to maple keys).

Tree of Heaven reproduces both by seed and vegetatively. The winged seeds can utilize wind corridors and travel far from the parent plant. The seeds generally have germination rates and don’t remain viable in the soil for long, but a tree can produce over 300,000 seeds each year, so the sheer number of seeds makes up for the reduced germination rates. Tree of Heaven also commonly produces new individuals by sending up suckers from its roots, quickly spreading existing infestations further.

As mentioned earlier, Tree of Heaven acts as a host for the invasive Spotted Lanternfly, which is a reason for concern in BC. At this point, Spotted Lanternfly has not been found in BC yet, but it has been found in upstate New York near the Niagara region, which is alarming because this pest feeds on fruit trees and vineyards. You can learn more about Spotted Lanternfly on this page.

Tree of Heaven’s leaves are both unappealing to wildlife and toxic to other plants. They contain allelopathic compounds that are released when the leaves decompose, inhibiting the germination and root growth of other nearby plants. Tree of Heaven causes a loss of biodiversity that affects the entire ecosystem. What’s more, its pollen and sap are also known to cause allergic reactions in some people.

Tree of Heaven is sometimes confused with the native Smooth Sumac due to its very similar leaf structure. However, Smooth Sumac produces clusters of small red berries, while Tree of Heaven produces winged seeds. In the fall, Smooth Sumac leaves turn red, whereas Tree of Heaven’s turn yellow.

Per SSISC’s Invasive Plants Priority List, Tree of Heaven is listed as a species to eradicate in Squamish and is on the prevention watchlist in Whistler and Pemberton. We rely heavily on reports from the public to understand the current distribution of plants in the Sea to Sky and prevent their spread. With that in mind, we invite you to keep your eyes peeled for Tree of Heaven and report any sightings

Photo credit: R. Gardner, Bugwood.org
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