Black Cottonwood Populus trichocarpa — the PNW’s premier morel tree
Black cottonwood (Populus trichocarpa) is the largest deciduous tree native to western North America and for PNW mushroom hunters, it’s one of the most important trees for early spring foraging. Morel mushrooms fruit prolifically under and around cottonwood in riparian areas, making cottonwood bottomlands a top spring destination.
These fast-growing trees are easy to find: follow any river, creek, or wetland edge in western Washington or Oregon. Cottonwood thrives in riparian zones from sea level to mid-elevation, often forming dense stands along braided river channels and floodplains.
Map Black Cottonwood Habitat on Forayz
The Forayz map includes a Black Cottonwood habitat layer sourced from LANDFIRE vegetation data. Find cottonwood stands near you before your next spring outing.
Identification
Cottonwood is distinctive enough that with practice you’ll recognize it from a distance — especially in late spring when the fluffy white cotton fills the air. Narrow it down in western Washington by eliminating the two other common large deciduous trees: red alder and bigleaf maple.
Leaves
Oval to heart-shaped with a tapered tip. Smooth, somewhat shiny surface. Edges very slightly serrated. Underside is pale, often silvery. Red alder leaves are heavily serrated; bigleaf maple leaves are lobed.
Bark
Dark gray-brown with deep furrows on mature trees. Bigleaf maple has similar furrowed bark. Red alder is smooth and pale — easy to distinguish. Young cottonwoods have smooth greenish-gray bark.
Stature
Tall and straight-trunked, often not forking until the upper canopy. In good bottomland sites, 100+ feet is common. Red alder often forks low; bigleaf maple tends toward a rounder, more branched crown.
Where to Find Cottonwood
Follow the water. Cottonwood grows along rivers, streams, lake margins, and wetland edges throughout the PNW lowlands. River trails and park greenways near urban areas often have excellent cottonwood stands. Look for the fluffy white seed cotton in May and June.
Range
Black cottonwood ranges from Kodiak Island, Alaska to northern Baja California, and east to the Rocky Mountains. It’s most abundant in the Puget Sound basin and the Columbia and Willamette River basins. Growth is fastest on deep alluvial soils with good moisture — exactly the kind of riverside habitat that also produces morels and Verpa.
Distribution in Washington & Oregon
Associated Mushrooms
Cottonwood supports several notable fungi — morels in spring are the main draw, but the tree also hosts saprotrophic species on deadwood year-round.
Oyster Mushroom
Pleurotus ostreatus
Common on dead and dying cottonwood, often fruiting in large clusters. Found year-round but most productive in fall and mild winters. One of the easier edibles to identify.
Saprotrophic Choice Edible Fall–WinterVelvet Shank
Flammulina velutipes
The wild ancestor of cultivated enoki. Grows in tight clusters on cottonwood and other hardwoods in late fall and winter, often when temperatures drop near freezing. Recent research suggests the common species in Cascadia may be F. filiformis rather than F. velutipes, though distinguishing them requires DNA sequencing.
Saprotrophic Edible Fall–WinterVerpa
Verpa bohemica
Often the first morel-like mushroom of spring, fruiting in cottonwood bottoms a week or two before true morels appear. Cap hangs free from the top of the stem — a key distinction from true morels.
Mycorrhizal SpringPlan Your Spring Morel Hunt on Forayz
Use soil temperature, precipitation data, and the cottonwood habitat layer together to find the right conditions. Pro members get full access to overlays and burn perimeter data.
Also on iOS: ForayzU
Practice identifying Pacific Northwest trees and mushrooms with spaced-repetition flashcards — including a dedicated tree identification deck.
Ecological Role
Black cottonwood is a pioneer species — one of the first trees to colonize disturbed riverbanks after floods. Its extensive root systems stabilize soil and prevent erosion. Dense cottonwood stands create critical riparian corridors used by bears, deer, beavers, songbirds, and countless insect species.
Cottonwood commonly grows in mixed stands with willows, red alder, Oregon ash, and bigleaf maple. It’s intolerant of shade but grows fast enough to maintain canopy dominance. Trees begin producing seed around age 10 and set abundant crops most years — the familiar white fluff of June is cottonwood seeds dispersing by wind.
The Coast Salish people used cottonwood resin medicinally and the inner bark as food. Today it’s harvested commercially for particle board, plywood, and veneer.
Photos: Black Cottonwood — iNaturalist (CC0) · Morel — Kari Moreland (CC0) · Velvet Shank — © Dave W, CC BY-SA.