Despite How Foul They Smell, Cities Plant Ginkgo Trees By The Thousands Because They’re?
Answer: Pollution Hardy
There’s a good chance that if you live in a city somewhere in America, then you’re familiar with the ginkgo tree even if you don’t know its name. The tree is heavily planted in urban areas, has beautiful fan-like leaves, features a rough and highly textured bark, turns a brilliant gold color in Autumn, and–this is the part that might jog your memory–it smells absolutely awful.
Specifically, the female ginkgo tree (the species is dioecious and the trees are either male or female), produces a small attractive fruit in pairs upon the ends of its leaf stalks. While the fruit might be attractive in appearance, it is certainly not attractive in scent. The mature fruit fall to the ground by the hundreds and, due to the butyric acid found in the fruit, release a nauseating scent that permeates the air around the trees. While the specific scent signature registers differently depending on who is smelling it, most people describe it as smelling overpoweringly like vomit, rancid milk or butter, or a gym bag (unsurprisingly, butyric acid plays a big role in our aversion to those smells too).
So why is this tree found by the hundreds of thousands across urban areas as geographically diverse as London, Los Angeles, and Sydney if it smells so bad? Because it can survive the foul air we throw at it quite well. Back in the early 19th century, the pollution levels in heavily industrialized London were taking a toll on local trees. Despite the pollution levels, however, the ginkgo trees (imported from Asia and found in London’s botanical gardens) seemed absolutely no worse for wear even while their native counterparts withered (modern studies would establish that ginkgo trees could easily out survive other trees in urban environments by over a century). Once this reputation for urban hardiness was established, London urban planners as well as urban planners across the globe began planting ginkgo trees by the thousands.
Alas, the solution to avoiding the foul smell of the fruit-bearing female ginkgo trees isn’t to simply plant only male trees. Much like some frog, fish, and snake species can change their sex to adapt to a shortage of breeding partners in their environment, the ginkgo tree can also shift from male to female–meaning even the most careful urban planning department can end up with hundreds of city streets dotted with stinky trees despite their best efforts.