Rhamnus alnifolia
Alder buckthorn, Alder Buckthorn
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Family: Rhamnaceae · Type: Shrub · Native
Conservation status: CNPS 2B.2
Rhamnus alnifolia (Alder buckthorn) is a native California shrub in the Rhamnaceae family, recognized by high elevation wetland habitat, deciduous leaves, and black fruits.
Alder buckthorn is a California native shrub ranked 2B.2 by CNPS, found in the northern Sierra Nevada Mountains in wet meadow edges, seeps, and stream sides at elevations of 1,450 to 2,020 meters. Flowering from May to July, this plant produces small, subtle flowers in clusters of 1 to 3 on short pedicels. Growing to less than 2 meters tall with gray bark and puberulent branches, it develops brown twigs and winter bud scales about 5 millimeters long. Its deciduous leaves are elliptic to ovate, 45 to 110 millimeters long, with thin, translucent blades and prominent arched veins, featuring an irregularly toothed margin. The shrub produces a distinctive black, three-stoned fruit approximately 8 millimeters long.
Identification and appearance
Key characters: 2 sympatric species; distinguished by high elevation wetland habitat, deciduous leaves, and black fruits
Habitat and range
Habitat: Wet meadow edges, seeps, stream sides
Elevation: 1450-2020 m
California counties: Placer, Mendocino, Plumas, Nevada, Tehama, Sierra, Lassen, El Dorado
Outside California: to Canada, northern Rocky Mountains, northern United States
Bloom period
Rhamnus alnifolia blooms May-Jul.
Conservation status
CNPS 2B.2
How to tell it apart
vs Ceanothus: Rhamnus has tiny inconspicuous flowers; Ceanothus has showy white or blue flower clusters.; vs Quercus: Rhamnus has thin leaves and berry fruits; Quercus has thick leaves and acorns.; vs Prunus: Rhamnus fruits have 2-4 stones inside; Prunus has single large stone (pit).; vs Rhus: Rhamnus has simple leaves and scaly buds; Rhus has compound leaves and hairy fruits.; vs Frangula: Rhamnus buds have protective scales; Frangula buds are completely naked.
Frequently asked questions
Is Rhamnus alnifolia native to California?
Yes. Rhamnus alnifolia is native to California (recorded as native).
When does Rhamnus alnifolia bloom?
Rhamnus alnifolia blooms May-Jul.
Where in California does Rhamnus alnifolia grow?
Rhamnus alnifolia occurs in Placer, Mendocino, Plumas, Nevada, Tehama, Sierra, Lassen, El Dorado, at elevations of 1450-2020 m.
What plant family does Rhamnus alnifolia belong to?
Rhamnus alnifolia is in the Rhamnaceae family, genus Rhamnus.
Is Rhamnus alnifolia rare or endangered?
Rhamnus alnifolia carries California Rare Plant Rank 2B.2, state rank S3.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · CNPS Rare Plant Inventory · Index of California Plant Names · CalPhotos · CDFW CNDDB
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.