Sargassum aquifolium

Thallus tough, to 1 m high. Main axis short, cylindrical, smooth, 5-10 mm high, to 2 mm diam. Primary branches compressed, smooth, bearing secondary cylindrical branches arranged alternately. Phylloids alternate, of equal thickness, elliptical to oblong, to 3 cm long, 1.0-2.0 cm broad, slightly asymmetrical or cuneate at base on short stalk. Tips rounded with thick two-edged margins. Margins undulate, with double rows of coarse teeth. Midrib vanishing at the middle or upper part of phylloids. Vesicles spherical to oblong or elliptical, slightly compressed, with spines or foliose wings at margins, 10(-15) mm long, 5-10 mm wide. Stalk flattened or foliaceous, sometimes serrate at margins. Cryptostomata scattered on both surfaces of phylloids and vesicles. Receptacles compressed, dentate, forked, in compact clusters. Holdfast conical-discoid, 1.0 cm diameter. Growing on rocky bottom.

Tropical and subtropical waters of Atlantic and Indian Oceans.