Tall robust perennials or occasionally annuals. Leaves: ligule membranous, or a shortly-ciliate membrane; blade linear-lanceolate, cordate at base, flat, with distinct yellowish midrib and margins, scabrid on blade and margins. Inflorescences axillary and terminal, monoecious, consisting of a solitary spike-like raceme subtended by a spathe which encloses it when young, sometimes several spathes arising from the one node, the spike-like raceme is comprised of two zones, a basal zone of solitary female spikelets stacked end to end and disarticulating at the nodes, and an apical zone of paired male spikelets. Female spikelets solitary and sessile, closely appressed to rachis; glumes unequal; lower glume symmetrical, rounded or swollen and the sides enclosing the spikelet and wholly or partially enclosing internodes, smooth or finely pimpled, and shiny, very thick and hardened; upper glume smaller, almost flat, cartilginous but much thinner in texture than the upper glume; lower lemma present; lower palea absent; upper lemma narrower and thinner than lower lemma; upper palea present. Caryopsis enclosed in the hard lower glume. Male spikelets in pairs, one distinctly sessile and the other pedicellate, the pedicel only shortly free and adherring to internode for most of the length; each with 2 florets. Sessile spikelet: lower glume with marginal flaps, symmetrical, herbaceous; upper glume distinctly or indistinctly 2-keeled, symmetrical, herbaceous to membranous; lemmas and paleas similar in size and shape, hyaline; stamens 3. Pedicelled spikelet: lower glume asymmetrical with marginal flaps, herbaceous; upper glume distinctly 1-keeled, herbaceous to membranous; 2 florets with lemma and palea present, similar in size and shape, slightly shorter than spikelet; lower floret fertile with stamens, upper floret sterile, underdeveloped or sometimes with stamens.
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Perennial or annual. Leaf blades linear; ligule membranous. Inflorescences axillary, of single racemes, each usually supported by a spatheole, often gathered into a spathate compound panicle; racemes bearing pairs of unisexual awnless spikelets, female and male spikelets separated into different zones, female pairs below male pairs, axis fragile between female pairs. Rachis internode and pedicel fused along one margin; callus truncate with central knob. Female zone: sessile spikelet dorsally compressed; lower glume leathery to bony, enveloping spikelet, body smooth or transversely constricted, flanks usually winged above; lower floret sterile, palea usually absent; upper floret pistillate, palea present; pedicelled spikelet reduced to vestigial. Male zone: spikelet pair similar, both or only sessile staminate; lower glume herbaceous, elliptic-oblong.
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