A deciduous shrub 6 to 18 ft high in a wild state, with glabrous, purple branches. Leaves opposite, narrowly oval or ovate, 11⁄2 to 4 in. long, 3⁄4 to 2 in. wide, tapered or somewhat rounded at the base, blunt or pointed, rarely slender at the apex; dark green and slightly hairy above; pale and woolly beneath. Flowers yellowish, crowded densely in compact, rounded, downy cymes about 2 in. across. Fruit white.
Native of British Columbia south to California; introduced in 1874. It blossoms towards the end of May and in June, and is pretty then. It is also distinct in its dark purplish branches and in its leaves, woolly beneath. It is allied to C. stolonifera and not easy to distinguish from it, owing to the existence of natural hybrids (or perhaps intermediates) between the two (see below).
C. × californica C. A. Mey. C. torreyi S. Wats. – According to Rickett in North American Flora, Vol. 28B, p. 305, much of the material hitherto placed under C. pubescens Nutt. and C. torreyi S. Wats, represents hybrids between C. occidentalis and C. stolonifera. It should be noted, however, that neither Jepson nor Rehder recognised the existence of these hybrids. The former (Fl. Calif., Vol. 2, 1936, p. 677) treated C. occidentalis under the name C. californica C. A. Mey., and remarked that the intermediates (as he considered them to be) between this species and C. stolonifera made it difficult to draw a line between them. His suggestion that C. californica might best be treated as a variety of C. stolonifera was taken up by McMinn, who published the combination C. stolonifera var. californica (C. A. Mey.) McMinn.