Perennial from a creeping rhizome, this sometimes coarse and woody, but not tuberous-thickened; herbage usually loosely spreading-hairy as in no. 2, or the pubescence seldom approaching that of no. 1 [Parthenium integrifolium L.]; middle and upper lvs tending to be broad-based and ±strongly auriculate-clasping; heads larger than in no. 1 (the disk mostly 7-10 mm wide) and averaging fewer; achenes 3-5 mm; otherwise as in no. 1; 2n=72. Prairies and limestone glades; Mo. and adj. Kans. to n. La., Okla., and Tex., and adventive e. as far as s. Mich. May-July.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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