Alnus rubra

Red alder, Red Alder

Family: Betulaceae · Type: tree · Native

Red alder is a native tree found in northern coastal California, western Klamath Range, northern coastal Redwood, central coastal, and San Francisco Bay areas in wet places, especially after logging, at elevations below 1,000 meters. Flowering from February to March, this tree produces small, inconspicuous flowers in catkins. Growing up to 25 meters tall with a trunk of moderate width, it has a distinctive bark and branching structure. Its leaves are thick with rounded to tapered bases, acute tips, and tightly rolled margins, appearing gray-green on top with indented midribs and major veins, while the underside is similarly gray-green and covered with rusty hairs or rusty sessile glands. In disturbed wet areas, red alder plays a critical role in forest regeneration and soil stabilization.

Habitat: Wet places, especially after logging

Bloom period: Feb-Mar

Elevation: < 1000 m

Bioregions: NCo, w KR, NCoRO, CCo, SnFrB

California counties: Humboldt, Marin, Mendocino, Del Norte, Santa Cruz, Sonoma, Alameda, Contra Costa, San Mateo, Monterey, Santa Clara, Shasta, San Luis Obispo, Trinity, Siskiyou

Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Jepson eFlora, Cal-IPC, and more.