Populus trichocarpa aka Black Cottonwood

Populus trichocarpa is a large tree that sheds its leaves. Common names include black cottonwood and western balsam poplar. It belongs to the willow family, Salicaceae. Its home range spans much of western North America. It grows from southern Alaska south to California and northern Mexico. Its range also reaches east to the Rocky Mountains. Wild trees grow in moist woods, ravines, and shore habitats.

The tree grows fast, with a tall, straight trunk. Its crown stays narrow for such a large tree. Published sizes reach 131 feet [40 metres] tall in cultivation. The stated spread is about 39 feet [12 metres]. Larger trees can reach 150 feet [45 metres]. Young trees may reach 40 feet [12 metres] within 15 years. Older bark turns dark gray-brown, with ridges and deep grooves. The wood is brittle, which limits its landscape use.

The broad, egg-shaped leaves grow in an alternate pattern. Fine teeth line their edges. Their upper sides are dark green; their undersides look silvery. Brown resin marks may appear on the leaves. Pointed orange-brown buds carry sticky resin with a balsam scent. The scent grows stronger as new leaves open in spring. Male and female flowers grow on separate trees. Wind carries pollen between them during April and May. Female catkins lengthen as their small, round seed capsules develop. These split open and release seeds with silky white hairs. This cotton-like fluff can cause a nuisance near homes.

Give this tree full sun and room beyond competing roots. It prefers deep, rich soil that drains well but stays moist. It can grow in sand, loam, or heavy clay. It accepts acid, neutral, and mildly alkaline soils. Poor, dry ground can support it, but growth may slow. Very wet soil also reduces growth. Exposed upland sites do not suit it well. Sources place its hardiness within USDA zones 4–8. Its size suits a woodland canopy setting rather than small gardens.

People have used its bark for containers and cord. The buds yield a yellow dye. Shoots also supply extracts used to help cuttings root. Traditional herbal uses include care for wounds and chest complaints. These uses do not establish medical safety or benefit. Reported foods include inner bark, sap, and raw or cooked catkins. The catkins taste bitter, while fresh inner bark tastes sweet. The bark spoils fast after harvest. Plants For A Future lists no known hazards.