Contr. U.S. Natl. Herb. 4: 80, plate 6. 1893.
Shrubs, 0.5–1.5 m, sometimes moundlike. Stems erect, spreading, or weakly ascending, sometimes arcuate, rooting at proximal nodes; branchlets reddish to grayish brown, sometimes glaucous, rigid, glabrous or sparsely puberulent. Leaves sometimes fascicled, not crowded; petiole 1–3 mm; blade flat to slightly cupped, slightly folded lengthwise adaxially, widely elliptic to suborbiculate, 10–20 × 8–19 mm, base rounded, margins thick to slightly revolute, dentate to denticulate most of length, teeth 9–15, apex rounded, abaxial surface pale green, glabrous except on veins, adaxial surface dark green, glabrous. Inflorescences axillary, 1.2–2.1 cm. Flowers: sepals, petals, and nectary pale blue to blue. Capsules 6–9 mm wide, weakly lobed; valves smooth to rugulose, horns subapical, prominent, erect, rugose, intermediate ridges present.
Phenology: Flowering May–Jun.
Habitat: Rocky granitic or metamorphic slopes and ridges, open pine forests.
Elevation: 1600–2600 m.
Ceanothus pinetorum occurs disjunctly in the southern Trinity Mountains (Shasta and Trinity counties) and in the southern Sierra Nevada (Kern and Tulare counties).
"thick" is not a number.