Broadly defined, this eastern species is divisible into two taxa. Var. patula is centered in east-central states and may include all plants in Ky. However, colls. from BELL (GH) and CALL (MUR) have appeared transitional to var. strictula Torr. & Gray, which has distinctly higher involucres (mostly 3-5 mm high versus 4-7.5 mm); also, it tends to have relatively small, narrow leaves. Var. strictula occurs mostly in the Ozarks and on the southeastern Coastal Plain, and may be distinct enough to deserve species status as S. salicina Ell. (Cr, W; Semple et al. 2012). However, Semple et al. did not map it in Appalachian regions.