Plants annual or perennial; rhizomatous, stoloniferous, or cespitose. Culms 5-150 cm, not woody, branched above the base; internodes hollow. Leaves cauline; auricles sometimes present; ligules membranous, sometimes ciliate; blades flat or rolled, with or without cross venation. Inflorescences terminal, usually contracted, dense panicles, distal 1/2 of the rachises concealed by the spikelets; branches fused to the rachises or free and appressed to ascending; pedicels with discoid apices; disarticulation below the glumes and below the upper florets. Spikelets bisexual, with 2 florets, rounded to acute; rachilla internodes not swollen. Glumes unequal, prominently veined, unawned; lower glumes 3-7-veined; upper glumes as long as or exceeding the upper florets, distinctly saccate or gibbous, 5-13-veined; lower florets 0.8-1.9 mm, sterile or staminate, less than 1/2 as long as the spikelets; lower lemmas resembling the upper glumes but not saccate, sometimes with a transverse row of hairs, 5-9-veined, unawned; lower paleas present or absent, 0-2-veined; upper lemmas subcoriaceous to subindurate, dorsally compressed, glabrous, smooth, margins inrolled or flat, never hyaline, faintly 3-5-veined; upper paleas similar to the lemmas, 2-veined; lodicules 2, fleshy, glabrous. x = 9. Name from the Greek sakkion, small bag, and lepis, scale, alluding to the saccate upper glumes.
Spikelets with one perfect terminal fl, lanceolate, awnless, pedicellate, aggregated into a slender spiciform panicle; first glume short, triangular, 3-veined; second glume strongly saccate at base, sharply 11-13-veined; sterile lemma equaling the second glume, flat, 5-veined, the outer veins approximate in pairs near the margin, its palea nearly as long and often subtending a staminate fl; fertile lemma much shorter, short-stipitate, chartaceous, with involute margins clasping the margins (but not the tip) of the similar-textured palea.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.