What’s the Funny Smell?

Yesterday, Tracey asked me if I thought the air smelled like wet dog. I didn’t smell anything doggy and attributed her odd sense of smell to a headcold. But on Tuesday I thought the air was fresh and salty like the seaside.
At dinner last night, Jim asked if we thought the city smelled like old shoes. Tod agreed that it smelled weird; he described it as “cut grass that’s been sitting around.” Yuka suggested the scent reminded her of sperm. I sniffed long and hard but couldn’t smell anything over our newly planted lavender and mint.
Everyone seemed to feel unusually sleepy, too.
OK, something was definitely going on with the air.
Yuka says it’s from a tree, but she couldn’t remember the name. There are a lot of them near the Chinese Embassy, she says, and they smell bad when they are flowering. I wonder what tree it is…anyone know?