Plants perennial; cespitose, not rhizomatous. Culms 25-65 cm, erect or spreading, basal branching extravaginal; prophylls not visible; nodes glabrous. Leaves mostly basal; cleistogenes not developed; sheaths open, glabrous; auricles absent; ligules membranous, longest at the sides or rounded, ciliate; blades of basal leaves 30-90 cm, remaining green over winter, erect when young, recumbent in the fall, bases twisted, placing the abaxial surfaces uppermost, cauline leaf blades reduced, flag leaf blades 2-12 mm, conspicuously narrower than the top of the sheath. Inflorescences panicles, contracted. Spikelets 5-7.5 mm, with 1 floret; rachillas not prolonged beyond the base of the floret; disarticulation above the glumes, beneath the floret. Glumes subequal, 6-10-veined, apices mucronate; florets terete to laterally compressed; calluses usually less than 1/5 the length of the florets, blunt, distal portions pilose; lemmas coriaceous, pubescent at least basally, 3-5(9)-veined, margins strongly overlapping at maturity, awned, lemma-awn junction conspicuous, lobed, lobes 0.1-0.2 mm; awns more or less straight, deciduous; paleas similar to the lemmas in length, texture, and pubescence, concealed by the lemmas, 2-veined, flat between the veins; lodicules 2, free, membranous, 2-veined; anthers 3; styles 1, with 2 branches; ovaries glabrous. Caryopses falling with the lemma and palea. x = 11, 12. Name from the Greek oryza, 'rice', and opsis, 'appearance', in reference to a supposed resemblance to rice.
Spikelets 1-fld, articulated above the glumes; glumes equal or nearly so, herbaceous to membranous, broad, acute to acuminate, distinctly to obscurely 3-7-veined; lemma about equaling or a little shorter than the glumes, fusiform, nearly terete, obscurely veined, becoming indurate at maturity, with a short, oblique, blunt callus at base; margins of the lemma folded over a palea of similar or more membranous texture; awn terminal, articulated with the lemma, readily detached; tufted perennials with flat or involute lvs, membranous or no ligule, and open or contracted panicles or racemes of often large spikelets. 50, N. Temp. and subtrop.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
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