Rhizomes with 2 scales at each node. Erect stems absent. Leaves apparently attached to rhizome, 10--25 ´ 3--6 mm; blade oblong-elliptic, base cuneate, margins serrulate, apex obtuse to rounded, pubescent. Inflorescences: spathe enclosing both staminate and pistillate flowers. Flowers unisexual, staminate and pistillate on same plants; staminate flowers deciduous shortly after anthesis; pistillate flowers nearly sessile, 2 mm. Fruits ovoid. Seeds ca. 0.2 mm.

Flowering winter--spring. Sandy substrates of marine waters; -30--0 m; Fla.; West Indies; Central America (Panama, Costa Rica); South America (Venezuela, Colombia); Asia; Australia.