Sargassum cristaefolium C. Agardh
This species is widely distributed in the Philippine shorelines. It is a very good source of algenic acid, which is used in pharmaceutical industry as well as in fertilizer known as ALGA-FER (meaning algae fertilizer).
Thallus yellow brown, about 30 to 50 cm in height, arising from small discoid holdfasts, mostly growing on subtidal rocks or reefs. Main axis cylindrical, very short, only 2 to 3 mm long, 2 mm in diameter, giving rise to several primary branches, smooth, cylindrical or very slightly compressed. Secondary branches alternately arranged, beset with branchlets with copious leaves, vesicles and receptacles. Leaves oblong-elliptic or obovate, conduplicate at the apex, with sharp teeth at the margins and unequal cuneate bases, midribs disappearing below the apex. Vesicles spherical or obovate, often crowned with ear-like wings on both sides, borne on short foliar pedicels. Receptacles cylindrical, forked, with wartlike teeth, 4-5 mm long, 1 mm diameter in cymose glomerules.