Perennial, (15-) 30-70 (-100) cm tall, with erect to decumbent stem, often rooting below at the nodes, compressed to subterete; rootstock short, leaves 2-10, including basal and cauline, linear to filiform, obscurely septate, shorter than stem, acute; basal sheath with ± rounded auricles. Inflorescence laxly corymbose to umbellate-paniculate with erect to subspreading branches; floral heads c. 1 cm across, densely 6-10-flowered hemispherical; lowest bract ovate-lanceolate, much shorter than the inflorescence. Flowers greenish or brownish, 3.5-4.5 mm long, sessile; perianth segments ovate-lanceolate, very acute, subulate. Stamens usually 3, much shorter than the perianth, before the outer segments (sometimes 1-3 present before the inner segments also); anthers c; half as the filaments. Capsules equal to much exceeding the perianth, narrowly prismatic, 1-celled, pale brown to lutrous brown, many seeded. style very short; stigmas much longer; seeds minute, c. 0.6 mm long.