Why we’re stuck with The Stinky Tree

Our neighborhood walks often take us by what our family has come to call “The Stinky Tree.” My kindergartner in particular seems to relish the opportunity to share her disgust for the smell of its flowers, which has been likened to bleach, garbage, urine and more. It turns out that this species of tree, pyrus calleryana (aka Callery Pears and Bradford Pears,) plagues neighborhoods across the country. And it was put there entirely on purpose.

Repugnant but so resilient

The trees are native to China and Vietnam, but were imported to the United States in the early 1900s. It was praised for being so hearty, surviving blight, poor soil, proximity to asphalt, etc. It has a pretty (if smelly) white flower, and it was planted across the US in the 60s as an easy, ornamental plant that could survive a city.

Of course, as even my kindergartner could figure out, introducing a new species to an area that’s heartier than the native plants means those species will be pushed out. There tiny pear fruits are eaten and spread by birds, leading to further proliferation of the tree. Combined with the unwanted smell, this had lead some cities to stop planting Callery Pear trees after they’re sometimes killed by colder weather.

My kindergartner asked: So why does it smell bad? Functionally, the tree needs to attract pollinators like any other flowering plant. But it just so happens that a tree originally from a sub-tropical habitat evolved to attract things like flies and beetles, who prefer acrid, pungent smells.

Source: Pyrus calleryana, Wikipedia