Plains Cottonwood is a western subspecies of Eastern Cottonwood (Populus deltoides) that has slightly smaller leaves that are often broader than long and more coarsely toothed.
The Plains Cottonwood is a member of the willow family (family Salicaceae) which consists of deciduous, often aromatic trees and shrubs. About 350 species in the genera willow (Salix) and poplar (Populus); nearly worldwide, mostly in north temperate and arctic regions. 35 native and 5 naturalized tree species and about 60 native shrub species in North America. The large genus of willows (Salix), characteristic of wet soils, includes shrubs and mostly small trees, often with several stems or trunks from base and forming thickets. Leaves are narrow and commonly long-pointed and finely toothed, with distinct odor when crushed, turning yellow in autumn; leafstalks are very short with paired and often large stipules. Bark is gray or brown, smooth or becoming rough, scaly or furrowed, bitter, and aromatic. The slender or wiry twigs are tough, flexible, often shedding or easily detached at forks. The many tiny yellowish or greenish flowers usually appear in early spring before leaves; male and female are on separate plants, many crowded in mostly erect catkins. Each flower is above a hairy scale and has a glandlike disk, without calyx or corolla. Male flowers have 1-2 (sometimes to 12) stamens; female have a narrow pointed pistil. The many conical 1-celled long-pointed capsules along a slender stalk, are mostly light brown and mature in late spring or early summer, splitting into 2 parts. The numerous tiny seeds have tufts of white cottony hairs.