Two species: P. scouleri and P. torreyi. P. torreyi has narrow (1-2 mm), compressed, wiry leaves that are more firm and wiry than P. scouleri, and can reach up to 10 ft in length. P. scouleri leaf blades are flat and wide (2-4 mm), reaching no longer than 3 ft in length. Both are typically found at or below zero tide level or in mid- low tide pools. P. scouleri is mostly on rocks without sand inundation; P. torreyi is more likely to be found in sand-scoured areas.

Mostly intertidal, to shallow subtidal.

Sitka to Baja