Hypnea pannosa

Thallus subcartilaginous, tough, forming dense-intricate, caespitose, compact mats or cushions, 3-5 cm thick, up to 30 cm in diam., light to dark purple-red often with blue iridescence. Branching dense irregular, opposite to alternate, forming wide angles and rounded axils. Branches cylindrical or compressed, 1–3(5) mm broad, abruptly tapering towards the apices, anastomosed with other branches by dense rhizoidal tufts, densely covered with short lateral branchlets. Branchlets spine or spur-like, to 2 mm long, to 0.3–1 mm broad, not constricted at the base, with acute apices. Tetrasporangia irregularly zonately divided, 10–20x25–40 μm, develop in swollen portions of the basal and middle parts of branchlets, initially on abaxial side and latter sometimes encircling the branchlets. Cystocarps spherical, 500–700 μm diam., sessile or shortly stalked, develop on main axes. Attachment by pad-like holdfast. Growing in the low intertidal to upper subtidal zones.

Tropic and subtropics of Atlantic, Indian and Pacific Oceans. Countries of the Asian-Pacific Region: China, Korea, Japan, Taiwan, Vietnam, Thailand, Singapore, Indonesia, Philippines, Australia and New Zealand, Paciifc Islands.