Cottonwood seed dispersal
Cottonwoods, Populus deltoides, are dioecious, male flowers and female flowers are found on separate trees. The common name comes from the incredible mass of fluff that the female seed pods produce when they open. The seeds are tiny and the cottony material containing them is a great dispersal method traveling a long way from the mother plant. One tree can produce twenty-five million seeds each year.
In natural areas, this isn’t a problem but in cities, the fluff can be six inches deep around homes and on streets, clogging up gutters or air conditioner filters. You can’t use a blower to get rid of it – it’s too light weight to blow into a pile. Some cities outlaw female poplar trees; fortunately, there are male cultivars since cottonwoods may be the only trees that will grow there.