Holcus

Plants usually perennial, rarely annual; cespitose or rhizomatous, rarely both cespitose and rhizomatous. Culms (8)20-200 cm, glabrous or pubescent; nodes glabrous or retrorsely pubescent. Sheaths open; auricles absent; ligules 1-5 mm, membranous, entire or erose-ciliate, glabrous or puberulent; blades flat, pubescent. Inflorescences terminal panicles, contracted to open. Spikelets laterally compressed, with 2(3) florets, lower florets bisexual, upper floret(s) staminate or sterile; rachillas curved below the lowest florets, sometimes prolonged beyond the uppermost florets; disarticulation below the glumes. Glumes equaling to exceeding the florets, strongly keeled; lower glumes 1-veined; upper glumes 3-veined; calluses glabrous or pubescent; lemmas firm, shining, glabrous or pubescent, obscurely 3-5-veined, often bidentate; lower lemmas unawned; upper lemmas awned from below the apices, awns hooked or geniculate; paleas thin, subequal to the lemmas; lodicules 2, glabrous, toothed or not toothed; anthers 3; ovaries glabrous. Caryopses glabrous. x = 4, 7. Name from the Greek holkos, a kind of grain, perhaps sorghum.

Spikelets mostly 2-fld, disarticulating below the glumes; glumes thin, keeled, much exceeding and concealing the lemmas, the first 1-veined, the second broader, 3-veined; lemmas rounded on the back, obscurely veined, the lower awnless (in most spp., incl. ours), enclosing a perfect fl, the upper awned, with a staminate fl; awn arising below the lemma-tip; perennials (ours) with flat, soft, relatively wide lvs and dense, contracted, ovoid or subcylindric panicles of small spikelets. 8, Old World.

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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