Perennials, (5–) 13–40 (–70) cm tall, caespitose or with a short-creeping rhizome, or at times with stems submerged or buried in sand and rooting at proximal nodes. Stems erect or ascending or rarely floating, with 0–2 greenish to brownish basal sheaths and 3–7 cauline leaves. Leaves unitubular, perfectly septate, terete or somewhat compressed; auricles scarious, obtuse, to c. 1 mm long. Lower bract leaf-like, usually to 4 cm long, shorter than inflorescence. Stamens 6, (1/3–) 1/2–3/4 as long as tepals. Capsule unilocular, shortly mucronate, varying in colour. Seeds ovoid, 0.45–0.6 × c. 0.25 mm, pale brown, c. 25-striate, reticulate.