Page authors: Don Knoke, David Giblin
Alnus rubra
red alder

Distribution: Occurring chiefly west of the Cascades crest in Washington; Alaska to California, disjunct to the east in northern Idaho.

Habitat: Moist areas at low elevations.

Flowers: March-April

Origin: Native

Growth Duration: Perennial

Conservation Status: Not of concern

Pollination: Wind


Monoecious, deciduous trees to 25 m. tall, the bark thin, smooth and gray, the trunk up to 8 dm. thick; fresh wood tends to turn deep red.


Leaves alternate, simple, the blades broadly elliptic or elliptic-ovate, 5-15 cm. long, usually acute at each end, wavy and irregularly denticulate, the margins slightly revolute, the upper surface deep green and glabrous, the lower surface rusty-gray and gland-dotted.


Catkins developing before the leaves on growth of the previous season; staminate catkins clustered, pendulous, 5-12 cm. long; pistillate catkins cone-like, woody, ovoid-ellipsoid, 1.5-2 cm. long and 1 cm. thick, stout, thick peduncles under 1 cm. long.


Nutlet with thin, membranous wings 1/5-1/2 as broad as the nutlet

Accepted Name:
Alnus rubra Bong.
Publication: Mém. Acad. Sci. St.-Pétersbourg. Sér. 6, Sci. Math. 2: 162. 1833.

Synonyms & Misapplications:
Alnus oregona Nutt.
Alnus oregona Nutt. var. pinnatisecta Starker
Alnus rubra Bong. var. pinnatisecta Starker
Additional Resources:

PNW Herbaria: Specimen records of Alnus rubra in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Alnus rubra checklist entry.

OregonFlora: Alnus rubra information.

E-Flora BC: Alnus rubra atlas page.

CalPhotos: Alnus rubra photos.

USDA Plants: Alnus rubra information.

51 photographs:
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