Sargassum bicorne

Thallus leathery, bushy, to 1 m high. Main axis 5 mm long, 2.5 mm diam., giving rise to 5 cylindrical or lightly compressed branches of the first order, 40-80 cm long. Branching alternate. Branches of the second order 16–25 cm long, bearing branches 5–8.6 cm long. Phylloids oblong, lanceolate, 2–2.2 cm long, 6 mm wide with asymmetric base, serrate margins and midrib, vanishing below apex. Apex with double edges. Vesicles numerous, ellipsoidal, apiculate, small, 1-4 mm long, stalked, often alate at margins and with pappus or leaf formations in the upper part. Receptacles in axils, solitary, cylindrical, 3-4 mm long. Attachment by cone-like holdfast, 7-10 mm diam. Growing on lower intertidal to subtidal rocks.

Vietnam.