There are only two genera in this family, Salix (willows), with about 300 species, and Populus (poplars), with barely 40 species. Salicaceae are found throughout the temperate parts of the world, with the majority of species occurring in the north; both willows and poplars have a strong affinity for water, and are commonly found near ponds and along watercourses.

Willow bark was steeped as tea by native Americans, and the young twigs and bark chewed to relieve headaches. It was later found the active ingredient was salicylic acid, the basis of today’s aspirin. The chemical name for aspirin comes from the willow family name.

All reproductive events (pollination, fertilization, and seed dispersal) are wind-mediated within almost all species this family.  Cottonwoods, especially, are noted for their profusion of white tufted seeds, which can be produced in such numbers they accumulate in "snowdrifts."

Trembling Aspen (Populus tremuloides) is capable of producing new clone plants from rhizomes; a stand of thousands of Aspen "trees" can represent one individual. It is thought these are the largest (and perhaps oldest) organisms living today.

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