Sargassum swartzii

Thallus coarse, bushy, to 1.5 m high. Main axis short (to 10 mm high), cylindrical (2.5 mm diam.), smooth, bearing radially arranged several primary branches with thick, elongate-lanceolate phylloids, 4.7-6(-9) cm long, 5-7 mm broad. Phylloids with asymmetrical base, percurrent midrib, entire or shallowly dentate margins and acute apices. Vesicles stalked, solitary or in clusters, up to 8 mm long and 3-(4-5) mm diam., with rounded, pointed or mucronate apices; stalk flattened, cuneate, 8-12 mm long or sometimes longer than vesicle; cryptostomata small, scattered along the midrib and on vesicles. Receptacles 2.5-3.5(-5) mm long, 0.5-1.5 mm broad, compressed; slightly spinulose at apices, 2-3 times forked. Holdfast disc-like, to 12 mm diam. Growing on lower intertidal to subtidal rocks.

Tropics and subtropics of Indian and Pacific Oceans.