Althenia

Annual or perennial herbs. Rhizomes much-branched bearing roots, scale leaves and erect leafy shoots at nodes. Leaves frequently crowded at distal end of branches; floral leaves apparently subopposite; sheath with auricles well-developed; lamina linear. Flowers pedicellate, initially enclosed in a leaf-sheath. Male flowers with pedicel very short initially, elongating considerably at anthesis and extending beyond the leaves; anther or anther mass sessile, and subtended by 3 minute scales or scales fused and cup-like. Female flowers with 3 membranous and persistent scales; ovule 1 per carpel; styles slender. Fruit with style persistent.