Ceanothus thyrsiflorus
Blueblossom
(c) Henrik Kibak, some rights reserved (CC BY) · licence
Family: Rhamnaceae · Type: Shrub / Tree · Native
Ceanothus thyrsiflorus (Blueblossom) is a native California shrub / tree in the Rhamnaceae family, recognized by raised leaf veins and sticky hornless fruits.
Blueblossom is a California native tree found in coastal and interior mountain ranges in chaparral, coastal scrub, and coniferous forest habitats. Flowering from March to May, this plant produces stunning light to deep blue (occasionally white) flowers in compact raceme-like clusters 1.5 to 7 centimeters long. Growing up to 6 meters tall with flexible, angled green twigs, it develops an open, occasionally tree-like form with spreading branches. Its evergreen leaves are oblong-ovate to widely elliptic, 10 to 39 millimeters long, dark green on top and paler underneath, with gland-toothed margins and obtuse to rounded tips. The fruit is small and sticky, measuring 2.5 to 4 millimeters wide.
Identification and appearance
Key characters: 54 sympatric species; key features are raised leaf veins and sticky hornless fruits
Habitat and range
California counties: Humboldt, San Diego, Los Angeles, San Luis Obispo, Marin, Mendocino, Monterey, San Mateo, Santa Cruz, Santa Barbara, Alameda, San Francisco, Orange, Kern, Ventura, Del Norte, Santa Clara, San Bernardino, Yolo, Sonoma, Plumas, Lake, Contra Costa, Siskiyou, El Dorado, Trinity, Riverside
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 thyrsiflorus native to California?
Yes. Ceanothus thyrsiflorus is native to California (recorded as native).
Where in California does Ceanothus thyrsiflorus grow?
Ceanothus thyrsiflorus occurs in Humboldt, San Diego, Los Angeles, San Luis Obispo, Marin, Mendocino, Monterey, San Mateo and other counties.
What plant family does Ceanothus thyrsiflorus belong to?
Ceanothus thyrsiflorus is in the Rhamnaceae family, genus Ceanothus.
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.