Mem. Amer. Acad. Arts, n. s. 4: 29. 1849.
Shrubs, evergreen, 0.5–1.5 m. Stems erect, ascending, or spreading, rooting at proximal nodes; branchlets green to grayish green, thorn-tipped, round in cross-section, rigid, canescent, often glaucous. Leaves: petiole 1–4 mm; blade flat, elliptic, ovate, or orbiculate, 8–25 (–30) × 3–8 (–14) mm, base cuneate to rounded, margins usually entire, rarely serrulate near apex, teeth 3–7, apex obtuse to rounded, abaxial surface pale green or grayish green and glaucous, appressed-villosulous to tomentulose, especially along veins, adaxial surface dark green, dull, appressed-villosulous or glabrous; 3-veined from base (lateral-veins sometimes obscure). Inflorescences terminal or axillary, usually umbellike, sometimes racemelike, 1–3.5 cm. Flowers: sepals, petals, and nectary white or pinkish. Capsules 4–6 mm wide, lobed; valves smooth to rugose, viscid, usually not crested, sometimes weakly crested.
Phenology: Flowering Jan–Jul.
Habitat: Rocky soils, slopes, open sites, chaparral, oak-pine woodlands, conifer forests.
Elevation: 1400–2700 m.
Ariz., Colo., N.Mex., S.Dak., Tex., Utah, Wyo., Mexico (Chihuahua), Mexico (Coahuila), Mexico (Sonora)
Plants of Ceanothus fendleri with glabrous leaves found throughout its range have been called var. viridis. The name C. fendleri var. venosus has been applied to plants with widely elliptic, villosulous leaf blades. Such plants are similar to C. buxifolius of northern Mexico (Chihuahua and Sonora), which has glabrous or sparsely puberulent leaf blades and ± persistent glands on denticulate leaf margins. Putative hybrids between C. fendleri and C. herbaceus in the eastern foothills of the Rocky Mountains were named C. ×subsericeus Rydberg.
"thin" is not a number.