Plants with long creeping rhizomes, the stems mostly arising singly, 3-10 dm, densely stipitate-glandular, at least upwards, and often ±spreading-hairy as well; lvs chiefly cauline, thin, lanceolate, remotely and rather saliently dentate to entire, 4.5-13 cm נ8-40 mm, sessile and obscurely to usually ±evidently auriculate-clasping, glabrous or scaberulous above, softly hairy to glabrous beneath; heads several or occasionally rather many in a short infl, the invol 7-11 mm, its thin, slender, bracts acuminate or attenuate, often deep purplish, about equal, loose, the outer herbaceous to the base; rays 20-40, dark purple, 1-1.5 cm; achenes evidently nerved, sparsely short-hairy;
2n=18. Moist, open or wooded places; Isle Royale, n. Minn., and w. Ont. to Alas. and Oreg. (A. major)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.