Perennial; lvs 2-5 mm wide; rachis of the spike smooth except for the margins; florets mostly (2-)5-10; tip of the glume extending nearly or quite to the top of the lemma just above it; lemmas awnless. Var. aristatum Willd. Italian r. Annual or perennial; stems rough below the spike; lvs to 8 mm wide; rachis rough on the side opposite the spikelet; florets mostly 11-22; tip of the glume seldom extending to the top of the lemma just above it; lemmas, at least the upper, with awns to 15 mm. (L. p. var. italicum; L. multiflorum)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.