Fibrous-rooted from a short rhizome or caudex; stems 5-15 dm; lvs firm, mostly opposite, seldom ternate or alternate, entire or toothed, ovate or lance- ovate to elliptic, mostly 7-15 נ2-6.5 cm, 2-4 times as long as wide, scabrous above, sessile and often clasping; heads relatively large and many-fld, with mostly 16-35 (commonly ca 21 or 34) rays 2-5 cm, the disk mostly 1.5-2.5 cm wide; 2n=14. Prairies and roadsides, less often in open woods; s. Mich. to Neb., s. to Ala., Miss., and Tex. July-Sept. Two vars.:
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.