Ceanothus papillosus
Wartleaf ceanothus
(c) Ken-ichi Ueda, some rights reserved (CC BY) · licence
Family: Rhamnaceae · Type: Shrub · Native
Ceanothus papillosus (Wartleaf ceanothus) is a native California shrub in the Rhamnaceae family, recognized by glandular-papillate (warty) upper leaf surface.
Wartleaf ceanothus is a California native shrub found in the San Francisco Bay Area, southern Coast Ranges, western Transverse Ranges, and northwestern Peninsular Ranges in open sites, chaparral, and woodland at elevations of 90 to 1,500 meters. Flowering from March to May, this plant produces deep blue flowers in raceme-like clusters 2 to 6 centimeters long. Growing 1 to 3.5 meters tall with ascending to erect flexible stems that range from green to gray-brown, it forms an occasionally mound-like, dense structure. Its alternate evergreen leaves are thick and oblong to narrowly elliptic, 11 to 50 millimeters long, with dark green upper surfaces covered in glandular-papillate texture and margins rolled under with 17 to 31 tiny gland-teeth. The plant's distinctive leaves are notably thick and textured, with a unique glandular surface that gives it the characteristic "wartleaf" appearance.
Identification and appearance
Key characters: 35 sympatric species; glandular-papillate (warty) upper leaf surface is diagnostic
Habitat and range
Habitat: Open sites, chaparral, woodland
Elevation: 90-1500 m
California counties: Riverside, Santa Barbara, San Luis Obispo, Santa Cruz, Monterey, San Mateo, San Benito, Santa Clara, Ventura, Orange, Humboldt, Alameda
Outside California: northern Baja California
Bloom period
Ceanothus papillosus blooms Mar-May.
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 papillosus native to California?
Yes. Ceanothus papillosus is native to California (recorded as native).
When does Ceanothus papillosus bloom?
Ceanothus papillosus blooms Mar-May.
Where in California does Ceanothus papillosus grow?
Ceanothus papillosus occurs in Riverside, Santa Barbara, San Luis Obispo, Santa Cruz, Monterey, San Mateo, San Benito, Santa Clara and other counties, at elevations of 90-1500 m.
What plant family does Ceanothus papillosus belong to?
Ceanothus papillosus is in the Rhamnaceae family, genus Ceanothus.
What habitat does Ceanothus papillosus grow in?
Ceanothus papillosus grows in Open sites, chaparral, woodland.
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.