Bot. Gaz. 53: 68. 1912.
Shrubs, 0.1–0.3 m, matlike. Stems prostrate or spreading, rooting at proximal nodes; branchlets brown to reddish or grayish brown, rigid, tomentulose. Leaves not fascicled, sometimes crowded, not obscuring internodes; petiole 1–2 mm; blade flat or ± cupped, elliptic to oblanceolate, 4–12 × 3–8 mm, base obtuse to rounded, margins ± thick, not revolute, usually entire, sometimes minutely denticulate near apex, teeth 0–3, apex rounded to retuse, abaxial surface pale green, strigillose, adaxial surface dark green, shiny, puberulent, glabrescent. Inflorescences axillary, 1–2.3 cm. Flowers: sepals, petals, and nectary usually blue, rarely pale blue. Capsules 4–6 mm wide, weakly lobed; valves smooth, horns subapical, prominent, erect, intermediate ridges absent.
Phenology: Flowering May–Jun.
Habitat: Granitic soils and outcrops, semishaded sites, conifer forests.
Elevation: 400–2200 m.
Ceanothus fresnensis occurs infrequently along the western slopes of the Sierra Nevada, from Nevada County south to Fresno County. Despite its similarity to C. arcuatus, the two species can be separated by differences in life form and intensity of flower color. Ceanothus fresnensis tends to occur in relatively dense forests, whereas C. arcuatus occurs in open, relatively exposed sites, often at higher elevations.
"thick" is not a number.