Ceanothus prostratus var. prostratus
Shrubs, 0.1–0.2 m, matlike. Stems prostrate, with short erect shoots. Leaf-blades flat, margins not wavy, teeth usually 3–5 (–7). Capsule horns erect, rugose.
Phenology: Flowering Apr–Jun.
Habitat: Sandy or gravelly soils, open flats, gentle slopes, conifer forests.
Elevation: 400–2700 m.
Calif., Idaho, Nev., Oreg., Wash.
Variety prostratus often forms mats one to two and half meters wide.
"thick" is not a number.