Young twigs, peduncles, and leaves glabrous. 2n = 18.

Flowering Mar-May. Rocky or sandy soils, ravines, washes, slopes, rock outcrops, canyon walls, cliff faces, usually with other shrubs, especially Ambrosia, Yucca, Ephedra, Atriplex; (100-)500-1100 m; Calif., Nev.

Occasional, sparsely hirtellous plants may reflect genetic influence of var. spinosus.