Plants perennial; usually cespitose, sometimes shortly rhizomatous. Culms 5-130 cm, erect. Sheaths open; auricles absent; ligules membranous; blades flat to involute, pubescent or glabrous. Inflorescences panicles, usually dense and spikelike, sometimes lax, stiffly and narrowly pyramidal at anthesis; main rachis and branches pubescent. Spikelets laterally compressed, with 2-4 florets; rachillas to 1 mm, glabrous or pubescent, usually prolonged beyond the distal florets, or bearing a vestigial floret; disarticulation above the glumes and beneath the florets. Glumes subequal to or slightly exceeding the lemmas, membranous, scabrid to tomentose, keels sometimes ciliate; lower glumes 1-veined, somewhat narrower and shorter than the upper glumes; upper glumes obscurely 3(5)-veined; calluses with or without hairs; lemmas thin, membranous, 5-veined, margins shining, scarious, apices acute, sometimes mucronate or awned; paleas equaling or subequal to the lemmas, hyaline; lodicules 2, glabrous, toothed; anthers 3; ovaries glabrous. Caryopses glabrous. x= 7. Named for Georg Ludwig Koeler (1765-1807), a botanist at Mainz.
Spikelets normally 2-fld, disarticulating above the glumes and between the lemmas; rachilla prolonged behind the second palea and occasionally bearing a third, rudimentary or fertile, or a fourth rudimentary fl; glumes unequal, obscurely keeled, scarious-margined, the first 1-veined, the second 3-5-veined; lemmas about as long as the glumes, rounded on the back, acute, scarious at margin and tip, obscurely 5-veined; palea hyaline, nearly as long as the lemma; seeds with minute embryo and liquid endosperm; lvs narrow and shining; panicles contracted, silvery-green. 20, N. Temp. and Arctic.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.