Plants perennial; synoecious; rhizomatous, rhizomes short or elongate. Culms 50-250 cm, solitary or few. Leaves cauline; sheaths open; ligules of hairs, dense, short; blades elongate, long tapering. Inflorescences terminal, simple panicles, usually exserted and exceeding the upper leaves, open to contracted; panicles 8-80 cm long, to 60 cm wide, simple, flexible, branches not spikelike, not disarticulating. Spikelets with 1 floret, laterally compressed, unawned; rachillas not prolonged; disarticulation above the glumes, achenes falling with the lemmas and paleas. Glumes subequal to unequal, 1-veined, acute; calluses evidently hairy, hairs 1/4-7/8 as long as the lemmas; lemmas similar to the glumes, from shorter than to longer than the upper glumes, 1-veined, acute, unawned; paleas longitudinally grooved; anthers 3, 2.4-5.5 mm; ovaries glabrous. Fruit an achene, pericarp free from the seed. x = 10. Name from the Greek kalamos, reed, and Vilfa, a genus of grasses.
Spikelets 1-fld, articulated above the glumes; glumes chartaceous, 1-veined, the outer ovate, the inner much longer, lance-ovate; lemma chartaceous, obscurely 1-veined, acute, awnless, the callus bearded; palea about as long as the lemma; rachilla not prolonged; rhizomatous perennials with overlapping basal sheaths and long, narrow, usually involute blades; ligule a dense fringe of short hairs; infl an open or contracted, ovoid to oblong panicle.
4, N. Amer.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.