Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Genus Description - Perennial 5–12 dm, thickened at the nodes, the lower internodes very short, the lowest node often disarticulating; sheaths pilose at the throat; blades 2–4 dm × 3–6 mm; infl narrow, purplish, 1–3 dm, the ascending branches fascicled; glumes lanceolate, mostly 1-veined, the first 2.1–2.6 mm, the second 2.4–3 mm; lemmas glabrous, acute or acutish, 3.4–4.5 mm; rachilla-joints 1.3–2 mm, glabrous or hairy, usually short-pilose at the top; 2n=36. Native of Europe, intr. in fields, meadows, and roadsides from Me. to Pa., w. to Ont. and Wis.