Sargassum polycystum

Thallus coarse, bushy, 1-2 m high. Main axis cylindrical, slightly compressed, warty, with simple or Y-shaped proliferations. Primary branches terete, with branched spines; phylloids ovate to oblong, 2-4 cm long and 8-12 mm broad, with asymmetrical or cuneate base; midrib distinct, vanishing below apex or percurrent; margins with coarse teeth. In secondary branches phylloids linear-lanceolate with asymmetrical base. In branchlets phylloids narrowly lanceolate, 10-12 mm long, 2-3 mm broad with dentate margins; midrib indistinct. Vesicles stalked (terete), solitary or in clusters, small, spherical or ovate, 2-2.5(-3) mm diam., entire or with ear-like wings on both sides, crowned with a leaflet or mucronate. Cryptostomata prominent, on both sides of phylloids and vesicles. Receptacles cylindrical or compressed with toothed margins, simple or forked, clustered at base of phylloids and vesicles. Holdfast discoid (to 7 mm diam.). Growing on rocks, stones in lower intertidal to subtidal.

Warm seas of Pacific, Indian and Atlantic Oceans.