E-Flora BC: Electronic Atlas of the Flora of British Columbia

Family Description:
Members of this family are upright or crustose. When upright, the lateral branches are of limited growth. The medulla is composed of elongate, parallel, colorless cells surrounded by a transition zone of shorter, colorless cells. The cortex is composed of short, parallel files of pigmented cells, with swollen terminal cells. Cells in the holdfast can have many discoidal chloroplasts. Otherwise, characters are as described for the order.

Species description:
This light to dark brown seaweed has a perennial, encrusting holdfast up to 5 cm (2 in) in diameter. In the spring, erect branches arise from this holdfast, and these persist until late fall. The erect branches are up to 35 cm (14 in) high and have numerous radially-arranged lateral branches. These lateral branches are often distinctly flattened and somewhat curled, and can be up to 3 cm (1.2 in) in length, but they remain unbranched. Both the main axes and the side branches are solid in young individuals but become hollow as they age.

This species commonly grows on rocks that are moderately to fully exposed to strong surf, but is seen occasionally on more protected shores.