Fluffly white stuff

I saw some fluffy white stuff floating through the air.  It was like what dandelions get, but it had to be from a tree, not dandelions, because there was so much of it and it was so high in the sky.  Then I saw a bunch of it on the ground below a cottonwood tree, and I realized, that's what tree it came from.  And, that's why they call it cottonwood.