Ceanothus incanus
Coast whitethorn
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Family: Rhamnaceae · Type: Shrub · Native
Ceanothus incanus (Coast whitethorn) is a native California shrub in the Rhamnaceae family, recognized by white flowers are distinctive among predominantly blue-flowered relatives.
Coast whitethorn is a California native shrub found in the northwestern coast, central coast, and San Francisco Bay Areas in chaparral and mixed-evergreen forest at elevations below 900 meters. Flowering from April to June, this plant produces white flowers in panicle-like clusters 3 to 7 centimeters long. Growing to 4 meters tall with ascending to erect stems and rigid, pale gray to gray-green twigs, it has a distinctly open structure. Its alternate evergreen leaves are widely ovate, 20 to 50 millimeters long, dull green on top, gray-green underneath, with three prominent ribs from the base and entire margins. The fruit is sticky and 4 to 6 millimeters wide, developing a coarse, wrinkled texture when dry.
Identification and appearance
Key characters: 51 sympatric species; white flowers are distinctive among predominantly blue-flowered relatives
Habitat and range
Habitat: Flats, slopes, chaparral, mixed-evergreen forest
Elevation: < 900 m
California counties: Humboldt, Mendocino, Santa Cruz, Alameda, Napa, Lake, Plumas, Sonoma, San Francisco, Santa Clara, Monterey, Marin, San Mateo, Siskiyou
Bloom period
Ceanothus incanus blooms Apr-Jun.
How to tell it apart
vs Rhamnus: Ceanothus has showy blue/white/pink flowers in dense clusters; Rhamnus has tiny inconspicuous greenish flowers.; vs Quercus: Ceanothus has showy flower clusters and small leaves; Quercus has acorns and distinctive lobed or toothed oak leaves.; vs Baccharis: Ceanothus has individual flowers with 5 separate petals; Baccharis has composite flower heads with tiny disc flowers.; vs Cercocarpus: Ceanothus has blue/white/pink flowers in clusters; Cercocarpus has tiny flowers with no petals and feathery fruiting tails.; vs Adenostoma: Ceanothus flowers have 5 distinct colored petals; Adenostoma has tiny white flowers and needle-like clustered leaves.
Frequently asked questions
Is Ceanothus incanus native to California?
Yes. Ceanothus incanus is native to California (recorded as native).
When does Ceanothus incanus bloom?
Ceanothus incanus blooms Apr-Jun.
Where in California does Ceanothus incanus grow?
Ceanothus incanus occurs in Humboldt, Mendocino, Santa Cruz, Alameda, Napa, Lake, Plumas, Sonoma and other counties, at elevations of < 900 m.
What plant family does Ceanothus incanus belong to?
Ceanothus incanus is in the Rhamnaceae family, genus Ceanothus.
What habitat does Ceanothus incanus grow in?
Ceanothus incanus grows in Flats, slopes, chaparral, mixed-evergreen forest.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
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.