Internodes of rhizome 2.5-3(-5) cm. Scales elliptic, membranous. Leaves narrowly linear, 4-11(-15) cm × 0.8-1.4 mm, veins 3, midvein conspicuous, basally gradually narrowed, lateral teeth conspicuous, apex trifid; sheaths 2-3 cm. Flowers small. Peduncle of male flowers 1-2 cm; anthers ca. 0.5 mm. Style of female flowers 3-4 mm, apical. Fruitlet ovoid, ca. 2.5 × 2 mm; beak apical, ca. 1 mm.
Fruit ovoid to globose, slightly compressed, 1.5– 2.5 mm long and 1.7– 2 mm in diam., with a 0.2– 1 mm long apical or lateral beak.
Pistillate flower with globose to ovoid ovary 1– 2 mm long, style 10– 42 mm long, terminal or lateral.
Leaf with sheath 1– 4 cm long; blade sometimes falcate, 5– 18 cm long, 0.25– 3.5 mm wide, base narrowed, apex with 2 linear lateral teeth and an obtuse (rarely acute) median tooth, midrib conspicuous, widening near the apex and sometimes furcate or bicuspidate.
Staminate flower with pedicel 6– 20 mm long; anthers 2– 5 mm long, red, the upper anther attached 0.2– 0.5 mm above the lower.
Gregarious marine herb; rhizome 1.5– 2.5 mm in diam.; each node with 1– 6 roots and erect stem to 5 cm long; internodes 0.5– 5 cm long; scales ovate or elliptic, 4– 9 mm long.
Grass-like perennials. Roots up to 6, arranged in a semi-circle at the nodes of the main rhizome, simple, long, densely covered with long root-hairs; the roots from the abbreviated nodes of the rhizome-branches appearing singly, inserted left and right to form a double row. Rhizome with internodes up to 4 cm long, giving off much abbreviated side branches with internodes 0.5-3 mm long, ending in a leafy shoot; the internodes covered at first with membranous long, imbricate, amplexicaul, convolute bracts, their blackish bases persistent, giving the rhizome-branches their typical beaded appearance. Leaves 2-4 on very short, erect shoots; leaf-sheaths (the lower without a lamina) long, folded, biauriculate; lamina linear to setaceous, straight or somewhat falcate, flat, dark green, c. 100 mm long and 2 mm broad, midrib and margins terminating above in 3 short teeth, the truncate area between the teeth sometimes slightly convex or concave, often with a dark spot below the median tooth; secondary nerves indistinct, lamina with scattered tannin cells. Flowers solitary, beside a young leaf, surrounded by membranous, somewhat dilated sheaths; male pedunculate with one anther inserted above the other, the locules facing opposite directions; female with 2 carpels situated collaterally on a clavate peduncle which bears 3 small apical protuberances; style inserted laterally, long, subulate, ovule solitary, pendulous. Fruit globose, 1.5 mm in diam., hard, orange, papillate.