Sargassum micracanthum

Thallus coriaceous, 30-50 cm high, bright brown. Main axis short, cylindrical below bearing one to several primary branches three-ridged, more or less twisted and covered with prickles in the mid portion, above stem become flattened and anticipitous. Branches of the second order alternately arranged. Basal phylloids spatulate to lanceolate in shape, with short flattened stalk. Above phylloids pinnately deeply dissected, 4-6 cm long, 0.3-0.6 cm wide. Laciniae obliquely triangular, linear subulate or truncated. Vesicles solitary, stalked, ellipsoidal to ovoid or near to spherical, mucronated or crowned with a simple serrated leaflet on the top. Dioecious. Receptacles solitary, obovate, elliptical, flattened with anticipitous edges arranged in axils of phylloids and stalk of branchlets. Attachment by disc-shaped holdfast. Growing on rocks in the low intertidal to upper subtidal zones of open coasts.

Japan, Korea.