A close relative of the willow, the eastern cottonwood shares some of its characteristics. Also a dioecious plant, it bares pistils and stamens in catkins, although its catkins tend to droop, whereas willow catkins are normally upright or spreading. The cottonwood grows only as a tree, with spreading branches and a tall crown reaching heights of over 100 feet. Multi-stemmed cottonwoods may reach diameters of over 10 feet. The tree bark is nearly black, deeply furrowed, and decorated with resinous, many-scaled leaf buds in winter.
Leaves are simple and alternately arranged on the stems.
Cottonwood leaves have broad, flat bases that taper to a point near the tips. Leaf margins are deeply serrate and often curve inward towards the centermost veins of their blades. Both species are multi-stemmed shrubs commonly reaching a height of 8 feet. The flowers are borne in a cyme of four small petals and four minute sepals. Each flower forms a fruit, called a drupe, that bears a single seed.