Monday, December 3, 2012

The tree of anything-but-heaven

Species name: Ailanthus altissima

Common name: Tree of Heaven

Location: Ontario

Unfortunately, there are a couple pretty impressive specimens of the Tree of Heaven on campus, and this is only going to lead to disaster in a few years. The Tree of Heaven is a highly invasive species in North America, spreading underground via rhizomes and producing suckers that grow quite vigorously and grow in girth very quickly. This can not only be a menace to lawnmowers if this plant is in a decorative location, but they harbour a nasty secret underground. The Tree of Heaven produces some of the most toxic natural herbicides known, which successfully kill off any vegetation growing near them. While they don't seem to produce these chemicals in great numbers directly around their root system (other plants that aren't grasses can live happily in their shade if they are shade tolerant), they are produced in large amounts from the rhizomes to protect the developing suckers. This double-whammy of colonization and making the soil toxic to other organisms allows for their success at complete dominance over an ecosystem. They also thrive in disturbed areas where other species are slow to establish, also contributing to their success as an invasive species.

If you needed another reason not to plant this tree, it reeks. And I mean it smells TERRIBLE. The Chinese (the tree is native to China) even have their own traditional name for the tree: chouchun. Roughly translated, this means "malodorous tree." Other English names for this tree is the ghetto palm (not entirely sure how it got this name, but I kind of like it...) and the stinking tree. The odor probably has to do with the allelopathic compounds produced from the rhizomes; the suckers are especially disgusting after being "decapitated" with a lawnmower. It's almost enough to make you not want to go outside for fear of being drowned in their stench. On the bright side, this tree rarely lives past 50 years, so if you've got one in your yard you might want to remove it before it falls on your house.

Despite the incredibly foul smell produced from these trees, they are incredibly important in Traditional Chinese Medicine, where almost the entire plant is used for various purposes. A word of warning; this plant is toxic to humans as well as all other animal life so extreme caution should be exerted should you decide to go the TCM route. The bark is made into an astringent to treat a wide variety of diseases and disorders, from intestinal hemorrhaging to dysentery. There is also a significant amount of chemicals that are similar to quinones in the bark, and quinone is the most important antimalarial drug in the world. The drug-resistant malaria (or multi-drug resistant malaria) seems to still show strong effects of susceptibility to the ailanthone in the bark of the Tree of Heaven, and so is now a recognized antimalarial drug. The fruit of the tree when made into a tincture that effectively treats a vaginal infection called trichomoniasis, an infection caused by a protozoan that can be very difficult to treat. It is now the leading treatment for the infection by both doctors practicing Traditional Chinese Medicine and by doctors practicing Western medicine. It has also been suggested that this same medication will also have some effect on cancerous cells, but this has never been substantiated with clinical evidence. Extracts from the tree also have very potent anti-inflammatory effects, and have been shown to be incredibly effective at resolving severe allergic reactions (known as anaphylaxis).