Plants annual or perennial; sometimes shortly rhizomatous, cespitose or occasionally the culms solitary. Culms 5-110 cm, erect or decumbent, occasionally cormlike at the base; nodes glabrous. Leaves inserted mostly on the lower 1/2 of the culms; sheaths open; auricles absent; ligules 0.6-6.5 mm, truncate to acute, membranous, dorsally puberulent or glabrous, entire to lacerate; blades 0.7-12 mm wide, flat or involute, glabrous or scabrous, those of the uppermost leaves sometimes short or absent. Inflorescences terminal panicles, spikelike, capitate to cylindrical; branches usually less than 5 mm, lower branches sometimes to 2 cm; disarticulation below the glumes. Spikelets 1.8-7 mm, pedicellate, strongly laterally compressed, with 1 floret; rachilla prolongations absent. Glumes equaling or exceeding the florets, membranous or coriaceous, free or connate basally to more than 1/2 their length, 3-veined, keeled, keels ciliate, at least basally, apices obtuse to acute or shortly awned; calluses blunt, glabrous; lemmas membranous, margins often connate basally to 1/2 their length, keeled, indistinctly 3-5-veined, apices truncate to acute, awned dorsally, awns arising from just above the base to about midpoint, geniculate or straight; paleas absent or greatly reduced; lodicules absent; anthers 3, 0.3-4.1 mm; ovaries glabrous; styles fused, with 2 branches. Caryopses glabrous; hila short. x = 7. Name from the Greek alopex, fox, and oura, tail, referring to the cylindrical panicles.
Spikelets 1-fld, articulated below the glumes; pedicels conspicuously swollen at the joint; glumes equal, 3-veined, strongly compressed and keeled, ±connate at base, especially on the adaxial side; lemma thin and membranous, about as long as the glumes, 5-veined, the margins often ±connate, the midvein excurrent into an awn; palea in ours minute or none; low annuals and perennials with flat lvs, membranous ligule, and dense, cylindric or subcylindric, spike-like panicles. 25, N. Temp.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.