Herbs, rarely shrubs usually with long, stout roots, sometimes rhizomatous. Leaves alternate, basal and cauline; ochreae tubular. membranous, often entire. Flowers hermaphrodite or unisexual, arranged in whorls forming simple or branched inflorescences, anemophilous. Perianth-segments in two whorls of 3, the outer remaining small and thin, the inner becoming enlarged and often hardened in fruit. Valves (fruiting inner perianth segments) sometimes developing marginal teeth or dorsal tubercles as they mature. Stamens in two whorls of 3; anthers basifixed. Fruit a trigonous nut.