S. flexicaulis is a widespread species in eastern North America, but it is rare to absent on the southeastern Coastal Plain (where replaced by S. caesia var. zedia). There is significant variation; 2n = 18 and 36, or rarely 27 (FNA 20; Cook & Semple 2008). In Ky. typical flexicaulis mostly occurs on toe slopes and terraces with more base-rich soils, often with trees such as sugar maple and white ash. Plants mapped here may largely correspond to the widespread tetraploid race of flexicaulis (Chmielewski & Semple 1985; Cr, FNA 20; Cook & Semple 2008). Diploids occur mostly in northeastern regions, but are known from e. Ky. (see also, Esselman 1996. They appear difficult to distinguish from tetraploids, based on study of material at Univ. of Waterloo (WAT), but Peirson et al. (2012) indicated that diploids tend to have smaller heads. A similar cytogeographic pattern occurs in Helianthus decapetalus.