Perennial from scaly, often nodular-woody creeping rhizomes, 2-8 dm; stem commonly glabrous or nearly so, or short-hairy only just beneath the heads; lvs ±basally disposed, firm, glabrous or nearly so, grass-like, linear or nearly so, not veiny, only the midrib evident, entire or occasionally some of them remotely spinulose-toothed, to 20 cm (overall) and ca 1 cm wide, the lowermost sometimes deciduous, the lower tapering to a ±petiolar, sheathing base, the others progressively reduced and sessile; heads several in an elongate-racemiform infl (or the infl with spiciform or racemiform branches); invol campanulate or campanulate-hemispheric, 9-12 mm, glabrous, its bracts seldom much imbricate, linear-oblong, loose and often distally spreading, firm with chartaceous base and green tip, or the outer nearly wholly green, the outer more acute than the inner, the larger ones 1.5-2.5 mm wide; rays 15-35, deep lavender or purple, 1-2.5 cm; achenes glabrous or slightly strigose; pappus coarse and firm, the larger bristles flattened and often slightly clavellate; 2n=18 + 0-4 B. Prairies and open woods, less commonly in moist, low ground; Mo. to Tex., La., Tenn., and w. Fla. Closely allied to A. paludosus Aiton, of the coastal plain from N.C. to Ga., with broader, more corymbiform infl.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.