These midwestern plants were recently described by Mahoney & Kowal (2008). They were previously referred to the largely western P. plattensis (Nutt.) W.A. Weber & A. Löve, which has been confused with P. paupercula. Both species have been considered widespread and intergradient (Cr, Y). At leastr six Ky. colls. are tentatively mapped here but most need closer inspection: (1) from the Blue Licks in ROBE (B, based on a coll. of C.W. Short at CINC); (2) from the prairies of LEWI (M. Medley #19401-91 at APSC and J. Campbell s.n. for KY); (3) "plattensis" from "dry limestone slopes" in PULA (B, but not located at US); (4) from Davis Bend of Green Rv. in HART (NP coll. of M. Hines ca. 2010); (5) from BRAC but perhaps transitional to obovatus ("ravine at Milford" by R. Kral at APSC); and (6) from NELS but an incomplete coll. (R. Agnes #1314, "rich woods by stream" at DOV). P. plattensis was also reported from CASE by Murphy (1970) but the coll. has not been found at KY: "south side of Green River, old roadbed 3-4 miles south of Liberty." There is potential for confusion with var. appalachiana Mahoney, which has elliptic-oblong basal leaves (versus ovate-elliptic), more pinnatisect cauline leaves, less pubescence, shorter thicker rhizomes and smaller heads (Mahoney & Kowal 2008; W). Although reported from widely scattered Appalachian regions (W), var. appalachiana may not occur west of the Ridge and Valley (D. Estes, pers. comm.). Both taxa differ from typical paupercula and crawfordii in their pubescent cypselae, leaves and stems (versus glabrous); also, inflorescences are usually larger (with 6-50 heads versus 1-12).