• Photo by Alex Zimmerman
• Pyrus calleryana

Walk through any Pittsburgh neighborhood and chances are an unpleasant odor will eventually assault your nose: A pile of uncollected dog poop, dumpsters baking in the sun or a cloud of noxious exhaust from a passing bus.

Pause long enough and you'll identify another, difficult-to-place odor ... something that smells vaguely like rotting flesh, easy to write off as just a weird urban aroma.

That's the Pyrus calleryana, or the Callery pear tree, a plant the internet has dubbed the "semen tree" — for its prurient aromatic character.

"They’re actually not a good tree," says Margie Radebaugh, Director of Horticulture and Education at Phipps Conservatory, who says she hasn't smelled them.

But it's not just City Paper that noticed the smell: there are reports from New York to Maryland, as well as a Reddit post petitioning Pitt Chancellor Mark Nordenberg to "[invest] in trees that do not plague the student body."

The bad news, Radebaugh says, is the trees aren't going anywhere. Native to Asia, they were brought to the United States in the early 20th century for their resistance to disease and were eventually used for landscaping purposes.

The scent is designed to attract specific pollinators, much like the "corpse flower" which Pittsburghers turned out in droves to smell, according to Radebaugh.

The upside? You don't have to wait in line for hours to get a whiff.