This widespread eastern species is variable, especially in the Ozark region, but only diploids (2n = 18) are known. Most or all plants in Ky. are referable to var. ulmifolia, but colls. from HICK (JC for KY), CALL (M. Brock for APSC), TRIG and UNIO (GH, KY-Agr. and Purdue Univ.) may be transitional to the largely Ozarkian var. palmeri Cronq. That variant has relatively broad hairy leaves and stems spreading-hirsute below the inflorescence (versus glabrous); see Cronquist (1980), FNA 20 and W. The coll. from UNIO was misidentified as S. drummondii Torr. & Gray by Shacklett (1937) and Harvill (1941). S. ulmifolia has sometimes been reported to hybridize with rugosa and other species (F), but there has often been outright misidentification by striving solidaginists (Y).