The source of the smell

This spring, a large number of New Yorkers will have their noses assaulted by an unpleasant odor coming from the army of white-blossom covered trees that line many of the city’s streets.



These flowers, though lovely in appearance, smell like a mixture of rotting fish and semen, according to a variety of Web reports, and personal accounts from those in our own newsroom.

The raunchy-smelling flowers come from the Bradford Pear tree. Scientific name: Pyrus calleryana.

The trees were planted all throughout New York in the 1960s because they are hard to kill — they grow fast and can thrive in tough conditions. People also think they are pretty. In the eastern United States, they are considered an invasive species because of their prevalence.

The downside, we have learned, is that these hardy “street trees” really stink.

A path of pear trees

Urban Dictionary has labelled Bradford Pears the “semen tree,” with an equally inappropriate, though colourful, description of their smell, which you can read over there.

Everything we smell — from bananas to pine needles — comes from molecules, usually made of volatile chemicals, meaning chemicals that evaporate easily. The molecules evaporate from the food or flower and travel into your nose, where they bind with receptors in our nose.

The compounds that make the Bradford Pear tree’s flowers smell are likely due to a type of chemical called amines, Dr. Eloy Rodriguez, a professor of plant biology at Cornell University, told Business Insider.

We come in contact with the smell of amines every day in the form of body odours, like under the arm pits.

Plants that produce volatile amines, some that smell like rotting meat, use the gas either to attract flies who will then spread the flower’s pollen, or to ward off insects that might want to steal the nectar, said Rodriguez.

Rodgriquez suspects that the volatile compounds in the Bradfrod tree are there as attractants, and not necessarily to repel pollinators.

Later, the trees produce little green-yellow fruits that you cannot eat.

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