Man. Bot. San Francisco, 78. 1894.
Shrubs, 0.5–1.5 m. Stems erect to ascending, not rooting at nodes; branchlets reddish to grayish brown, rigid, puberulent, glabrescent. Leaves not fascicled, deflexed; petiole 0–2 mm; blade ± cupped, slightly folded lengthwise adaxially, elliptic to ± oblong, 10–20 × 5–13 mm, base rounded, margins thick or slightly revolute, spinose-dentate, teeth 7–11, apex rounded or sharply acute, abaxial surface pale yellowish green, glabrous, adaxial surface pale green, glabrous. Inflorescences axillary or terminal, 1–2 cm. Flowers: sepals and petals (5–) 6 (–8), usually blue to lavender or white, rarely pink; nectary blue; stamens (5–) 6 (–8). Capsules 5–7 mm wide, lobed; valves rugose, horns subapical, prominent, thick, erect, rugose, intermediate ridges present.
Varieties 2 (2 in the flora).
Ceanothus jepsonii, composed of two, allopatric varieties, is the only species with mostly six (rarely eight) sepals and petals, and cymules reduced to solitary flowers (M. A. Nobs 1963). T. M. Hardig et al. (2000) provided evidence showing that the two varieties may not form a monophyletic group. H. McMinn (1942) and Nobs (1963) reported putative hybrids with C. cuneatus and C. prostratus.
"thick" is not a number.