Robust, tufted, sometimes shortly rhizomatous perennial 1-3 m, sometimes sod-forming, often glaucous; blades usually 5-10 mm wide, the lower ones and the sheaths sometimes villous; racemes (2)3-4(-6), 5-10 cm, subdigitate, on a long-exserted peduncle; joints of the rachis and pedicels equal, subterete, sparsely or usually densely ciliate, densely bearded at the top; spikelets appressed, 7-10 mm, the glumes minutely scaberulous, often ciliate; awn of the fertile lemma 8-20 mm, twisted below and ±bent; pedicellate spikelet staminate, about as large as the sessile one; 2n=20, 40, 60, 80-86. Moist or dry, open places, a major constituent of the tall-grass prairie; Que. to Sask., s. to Fla. and Ariz. (A. furcatus; A. provincialis)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.