Description: Thallus is delicate, radially branched, light to dark red, and growing to 30 cm (12 in) tall. This species requires a microscope for accurate identification of polysiphonous branches (4 pericentral cells surrounding the axial cell) and lack of trichoblasts. Tip of each branch is capped with a rounded cell. Habitat: This perennial is found on rock or on other organisms in the low intertidal to subtidal of protected to semi-exposed habitats. Similar taxa: Polysiphonia spp., Pterosiphonia hamata, Antithamnionella pacifica.