As you may know, if you follow my Twitter updates, I recently complained that Hyde Park smells of semen all day, especially around the Serpentine. I cycle through there morning and evening and endure more or less endure the stench, but had very few people believe my plight.
For days I thought something perverted is happening near the serpentine, but thanks to a work colleague, I found out that it's actually true.
Apparently the Bradford Pear and a few varieties smell strongly like spunk when in bloom.
Here is a picture, unfortunately it's not the most brilliant quality:
Although the wikipedia article does not mention the smell, there are plenty of other sources on the net that do mention it, plus, it's on Y!Answers.
I read that this pear tree is preferred in urban areas, because it grows higher and not so wide as the average pear tree.
On the other hand, I wonder why the park authorities didn't plan ahead for this and chose to use other trees use that don't smell like the jizz?