Herbs, dioecious, rhizomatous, perennial; male plants with fertile and vegetative culms; female plants with vegetative culms and with spikelets terminating short stout subterranean stems. Rhizomes long, slender, glabrous, covered with glossy scales. Culms mostly widely separated on the rhizomes, glabrous or pubescent, striate, with short flattened lateral branches or terete and repeatedly branched; aerial stems all vegetative in females; the lowest internode similar to upper internodes or elongated and slender. Sheaths persistent, appressed, mucronate. Male spikelets solitary and terminal on culm branches, or many pedunculate spikelets in a slender inflorescence taller than the vegetative culms; with several or many flowers and often several sterile glumes. Female spikelets solitary, sessile on the rhizomes, so that the flowers and fruits are largely below ground, with only the long style, stigmas and tips of cataphylls above ground level; mostly 1-flowered, rarely 2-flowered, with many surrounding glossy bracts and a dense ring of long hairs between the bracts and tepals. Flowers with 6 hyaline tepals. Male flowers with 2 keeled outer tepals; stamens 3; anthers exserted. Female flowers with 1-locular ovary; style united in lower part but with 3 long red or purple stigmatic branches. Fruit a large (10–15 mm long), globular or obconical glossy nut, maturing below ground level. Culm anatomy: chlorenchyma of 2 or 3 layers of short peg-cells; chlorenchyma continuous in the lower part of the basal internode, interrupted by girders in the upper part of the basal internode, with elongated peg-cells and pillar cells in the upper culm branches; central ground tissue sclerenchymatous; central cavity absent.
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