Plants perennial; cespitose or loosely colonial, rhizomatous. Culms 35-150 cm, simple or branched. Leaves cauline; ligules membranous, ciliate; blades not pseudopetiolate, flat. Panicles open or contracted, sometimes becoming racemose distally; disarticulation above the glumes and between the florets. Spikelets 4-50 mm, laterally compressed, with 2-many florets, lower 1-4 florets sterile. Glumes 2, subequal, shorter than the spikelets, glabrous, (2)3-9-veined, acute to acuminate; lemmas glabrous, 3-15-veined, compressed-keeled, keels serrate or ciliate, apices acuminate to acute, entire (rarely bifid); paleas glabrous, gibbous basally, 2-keeled, keels winged, wings glabrous, scabrous, or pilose; lodicules 2, fleshy, cuneate, 2-4-veined, lobed-truncate; anthers 1; ovaries glabrous; styles 2; style branches 2, plumose, reddish-purple at anthesis. Caryopses 1.9-5 mm, laterally compressed, brown to reddish-black or black. x = 12. Name from the Greek chasma, yawn, and anthos, flower, presumably for the gaping glumes that expose the grain at maturity.

Spikelets 2-many-fld, flat, disarticulating above the glumes and between the lemmas; glumes shorter than the lemmas, acute or acuminate, 3-7-veined, compressed- keeled, the keel serrulate; lower 1-4 lemmas empty; lemmas acuminate, entire or bifid, 5-15-veined, compressed-keeled, the keel serrate or ciliate; palea firm, sharply 2-keeled, the keels arching and exposed; tall perennials from short or long rhizomes, with flat, serrate lvs and large, branched or spike- like panicles; ligule a short, hyaline, ciliate membrane. 5, e. and c. U.S. (Uniola, in part)

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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