Stems slender, 1-3 dm, scattered on slender rhizomes or arising from a subterranean root-crown, glabrous or sparsely strigose; stipules of the middle and upper lvs connate below, with greenish free blade; lfls 13-21, linear-oblong to lanceolate, sparsely hairy on both sides, the hairs basifixed; racemes dense, 2-4 cm, long-peduncled; fls strongly ascending or erect at anthesis, purple, 15-22 mm; cal ±hirsute, mostly with mixed black and white hairs, the subulate lobes half as long as the tube; fr erect, bilocular, obliquely ovoid, 7-10 mm, densely long-white-hirsute, deeply sulcate on the lower margin; 2n=16. Prairies, moist meadows, and stream-banks; Minn. and Io. to Yukon, s. to Kans., N.M., and Calif.; Eurasia. May. (A. gonialus; A. dasyglottis)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.