When its bark is damaged or when felled, the wood of this tree quickly oxidises to a bright rusty-red colour. Introduced by 1880.

Native to a 600km coastal strip of western North America, from southern Alaska to central California, often growing alongside conifers including Sitka Spruce (p. xxx), Douglas-fir (p. xxx) and Western Red Cedar (p. xxx).

Monoecious. Wind-pollinated. Wind-dispersed. Pioneer. Short-lived (60–80 years).

Medium-tall (25m), pyramidal, lightly and ascendingly branched. Bark grey, thin and fairly smooth. Twigs glabrous, waxy, often angular and ridged, with white lenticels and sticky resinous stalked buds. Leaves large (15cm), elliptical, on short petioles unusual for alders, slightly lobed and double-serrate, with revolute edges showing a thin green rim beneath. Male catkins 10-15cm; female woody cone-like. Grey Alder differs: hairy shoots, less lobed, non-revolute leaves.

Light-demanding and best in humid, cool conditions. Cold-hardy but sensitive to both spring and autumn frosts. It does not thrive on dry soils and is intolerant of wind exposure. It establishes very rapidly but begins to decline within 15 years.

No notable associations where introduced.

Susceptible to Phytophthora alni but less so than Black Alder.

Useful in establishing plantations as a sacrificial nurse species. Has some potential in short rotation forestry or agroforestry systems. North American timber sources provide the wooden bodies for a famous brand of electric guitars.