The willow family has many tree and shrub species. The family is most abundant in temperate regions of the northern hemisphere with about 120 species in North America. Aspens are the most important part of the willow family, at least in the Lake States.
All members have male flowers arranged in catkins that bloom in the spring.
Soon after, the female flowers ripen into tiny seeds that float through the are on milkweed-like fluffs. Although Populus is often a heavy seeder, regeneration is most commonly from root suckers . All family members have smooth, light-colored bark on trunks that are under a foot in diameter and on upper branches of large trees. BARK can be snow white, light gray, or a yellowish green. BARK on large, old trees turns medium-gray and develops deep furrows.