Plants 30-200 mm; stoloniferous. Stems erect. Leaf blades linear or lanceolate to oblanceolate; cauline 20-220 × 2-30 mm, bases not decurrent . Heads usually in corymbiform, sometimes paniculiform arrays, branches spreading to ascending, most bracts leaflike, 15-120 × 2-18 mm. Peduncles 5-220 mm; bracts 0-15, linear to subulate or ovate to oblanceolate, 2-12(-62) mm. Involucres 3-5 × 4-14 mm. Phyllaries in 3-5 series, subulate, linear, lanceolate, or spatulate, subequal, 0-6 merging down peduncles; outer 1.5-3.8 × 0.4-1.6 mm; inner 2.1-4 × 0.3-1.5. Ray florets 20-60; corollas white to lilac, laminae 5-13 mm, tubes 0.5-1.7 mm. Disc florets 65-170; corollas 1.5-2.6 mm. Cypselae obovoid, 1-3 × 0.8-2 mm, wings 0.1-0.5 mm wide; pappi awns 0.4-2 mm (lengths ± 2 / 3 cypselae). Variety asteroides is restricted to the coastal plain province. Varieties latisquama and recognita occur in the central lowland province and in the highland provinces between it and the coastal plain; var. recognita is also disjunct in Idaho and Oregon.
Plants 3-15(-20) dm, with or without rhizomes; lvs broadly linear to lanceolate or narrowly lance-elliptic, reduced upward, the larger ones 5-15 cm נ5-20 mm; infl commonly corymbiform, somewhat leafy, the lvs narrow, at least some of them over 1 cm; invol bracts ±imbricate; rays white to pink, purple or blue, (5-)8-15 mm; disk mostly 6-10 mm wide, with fewer than 200 fls; achenes evidently wing-margined; pappus-awns usually well developed, (0.2-)0.6-2 mm; 2n=18, 36. Moist or wet places; N.J. to Fla., w. to N.D., Okla., and Tex.; escaped and locally established elsewhere. July-Oct. Three vars.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.