Populus is a genus of 25–30 species of deciduous flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. English names variously applied to different species include poplar, aspen, and cottonwood.
Populus
Mature trembling aspen trees (Populus tremuloides) with young regeneration in foreground, in Fairbanks, Alaska
Male catkins of Populus × canadensis
The seeds of the poplar tree are easily dispersed by the wind, due to the fine hairs surrounding them.
The Salicaceae is the willow family of flowering plants. The traditional family included the willows, poplar, aspen, and cottonwoods. Genetic studies summarized by the Angiosperm Phylogeny Group (APG) have greatly expanded the circumscription of the family to contain 56 genera and about 1220 species, including the Scyphostegiaceae and many of the former Flacourtiaceae.
Salicaceae
Populus trichocarpa leaf margin showing a salicoid tooth. The brownish-yellow area in the axil of the tooth is the glandular seta.