Habit and leaf form. Herbs; evergreen. Switch-plants; with the principal photosynthesizing function transferred to stems (culms). Leaves well developed, or much reduced (the blade being much reduced). Perennial. Young stems smooth or minutely rugose; not breaking easily at the nodes. Stem internodes hollow (the pith cavity angular). Rhizomatous. Leaves alternate; distichous, or spiral; leathery, or membranous; sessile; sheathing (and more or less reduced to the sheaths). Leaf sheaths with free margins (persistent, mostly closely appressed). Leaves simple; with a persistent basal meristem, and basipetal development. Vegetative anatomy. Plants with silica bodies. Leaf anatomy. Leaf blade epidermis conspicuously differentiated into ‘long’ and ‘short’ cells, or without differentiation into ‘long’ and ‘short’ cells. Guard-cells not ‘grass type’, or ‘grass type’. Stem anatomy. Secondary thickening absent.
Reproductive type, pollination. Fertile flowers functionally male, or functionally female. Unisexual flowers present. Plants dioecious. Female flowers with staminodes. Male flowers with pistillodes, or without pistillodes. Floral nectaries absent (nectaries absent). Anemophilous.
Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; not in ‘spikelets’. Inflorescences scapiflorous, or not scapiflorous; terminal; many-flowered, clustered, similar in male and females. Flowers bracteate. Bracts 1 or 2, loosely sheathing with a long awn. Flowers bracteolate (usually), or ebracteolate. Bracteoles 1 or 2. Flowers cyclic. Perigone tube absent. Perianth of ‘tepals’; members 6; 2 -whorled; isomerous; sepaloid. Fertile stamens present, or absent (when female). Androecium 3. Androecial members free of the perianth; free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 3; becoming exserted; isomerous with the perianth; oppositiperianthial (opposite the inner perianth members). Anthers dorsifixed; versatile, or non-versatile; dehiscing via longitudinal slits; introrse, or latrorse; bisporangiate, or tetrasporangiate; appendaged, or unappendaged. Pollen shed as single grains. Fertile gynoecium present, or absent (male flowers). Gynoecium 3 carpelled. The pistil 1 celled, or 3 celled. Carpels isomerous with the perianth, or reduced in number relative to the perianth. Gynoecium syncarpous; synstylovarious; superior. Ovary unilocular, or plurilocular; 1 locular, or 3 locular; sessile to stipitate. Gynoecium stylate. Styles 1, or 3; when more than 1, free (arising from the outer corners of the ovary summit or when 1 not central on ovary, the bases persistent). Placentation when plurilocular, axile to apical. Ovules in the single cavity (when unilocular) 1; (when plurilocular) 1 per locule; funicled, or sessile; pendulous; non-arillate; orthotropous.
Fruit and seed features. Fruit non-fleshy; dehiscent, or indehiscent; a capsule (3-angled), or a nut. Capsules when dehiscent, loculicidal. Fruit 1 seeded, or 3 seeded. Seeds copiously endospermic. Embryo weakly differentiated. Seedling. Hypocotyl internode absent. Mesocotyl absent. Seedling collar not conspicuous. Cotyledon hyperphyll elongated; assimilatory; more or less circular in t.s. Coleoptile absent. Seedling cataphylls absent. First leaf centric. Primary root ephemeral.
Additional characters Perianth of male flowers of ‘tepals’; 6. Perianth of female flowers of ‘tepals’; 6. Leaf sheaths not striate. Caespitose, or not caespitose.