Ceanothus masonii

Mason's ceanothus, Mason's Ceanothus

Family: Rhamnaceae · Type: shrub · Native

Conservation status: CNPS 1B.2

Mason's ceanothus is a rare (CNPS 1B.2) California native shrub found in the San Francisco Bay Area's Bolinas Ridge in southwestern Marin County within rocky chaparral slopes at elevations of 150 to 450 meters. Flowering from March to May, this plant produces blue to purple-blue flowers in compact umbel-like clusters about 1 to 2 centimeters wide. Growing as an erect shrub less than 2 meters tall with ascending stems that are red-brown to dark brown and becoming gray-brown with age, it has a distinctive branching structure. Its opposite, evergreen leaves are obovate to narrowly obovate, dark green on top, with short white hairs underneath, and feature 9 to 17 teeth along the margins of blades 7 to 21 millimeters long. The fruit is approximately 4 to 5 millimeters wide with small horns less than 1.5 millimeters long.

Habitat: Rocky slopes, chaparral

Bloom period: Mar-May

Elevation: 150-450 m

Bioregions: SnFrB (Bolinas Ridge, sw Marin Co.).

California counties: Marin, Alameda, Trinity

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