Pretty. Stinky.

By Ryan Palumbo

I was recently reduced to a position not unlike one commonly assumed by a heaving cat while on my way up from University Heights to B'yond Style for my monthly haircut, as I passed by a row of trees sporting what anybody would surely consider to be a beautiful arrangement of white flowers from each branch. Curious.

The next day, while riding the #10 CDTA bus, I smelled it yet again. Unsurprisingly, those trees were around. At that I concluded that the miasma that had been violating my olfactory system for nearly a week had to be radiating from these trees.

I am sure many, if not all of you, have seen these trees as the warm weather gives way to the blooming of flowers and leaves, and have no doubt noticed that they STINK. And not only do they just stink: they seem to give off what some have called a particular, familiar odor ("fish that's been sitting out way too long" is another description).



Thus my research into these odorous organisms began.

The scientific name for the trees is Pyrus calleryana -- that is, they're pear trees. The variety is native to China and Taiwan, and was brought to the United States in the early 1900's to be used in hybridization experiments to produce a more fire-resistant pear tree; this proved unsuccessful. However, in the 1950s it emerged as an alternative ornamental tree, and was utilized extensively in landscaping due to its innate resistance to cold, disease, drought, fireblight, and pollution (it's been described as a "near-ideal street-tree"). However, the trees do have one weakness -- they tend to damage easily in strong wind. (I say: bring on the thunderstorms!) There are now a bunch of cultivars, the Bradford one of the most popular.

The Callery pear, as the trees are commonly known, is characterized in the springtime by clusters of white flowers at the tips of their branches that develop in March. Pretty. And stinky.

Which brings us finally to this: why does this tree smell so horrible? As far as I can tell, there isn't any research on why exactly the trees stink. However, I did come up with this: all of the approximately 30 species of pear contain the aroma compound pentyl butanoate. I will spare you the biochemistry -- this is the compound that makes pears and apricots smell as they do. One the precursors of pentyl butanoate is butyric acid, which is present in butter, parmesan cheese and... vomit.

But it appears that nobody has investigated the exact origins of P. calleryana's scent. And I don't blame anybody for not trying.