This saxicolous species is usually found in wave-protected areas. It is locally abundant to infrequent in the upper intertidal. This species is sometimes mixed with Fucus on rocks in Central California. In addition, this species is usually mixed with or located at slightly higher intertidal elevations than Silvetia compressa . Hesperophycus californicus is characterized by an erect and flattened parenchymatous thallus with regular dichotomous branching.
Branches contain a distinct midrib.
Two parallel rows of cryptostomata lie on either side of the midrib. Cryptostomata contain conspicuous, protruding white hairs. Thallus between dichotomies ranges from 3-12 mm in width. Receptacles are swollen and contain numerous chambers known as conceptacles. Conceptacles give rise to unilocular gametangia.