This taxon appears to be part of a variable hexaploid (2n = 102) complex that occurs mostly in the northern Great Plains and northeastern states. The more strictly western variant known as var. subrhomboideus (Rydb.) O. Spring & E.E. Schilling is unknown in Ky. But plants in Ky. need further study; in most cases it is unclear if the records mapped here are from native plants, adventive waifs, or escaped cultivars. See also notes under laetiflorus, a taxon that may be sometimes cultivated and considered adventive in eastern states by some authors (Clevenger & Heiser 1963; Cr, FNA 21). Colls. mapped here from EDMO (Harvill 1941), HARD (APSC, Okla. State Univ.) and JEFF (DHL) may represent true pauciflorus and perhaps native plants.