This southeastern species (up the Atlantic Coast to Mass.) includes a polyploid series (2n = 20, 30, 40), and may be derived from hybridization of rotundifolium and album (FNA 21). It appears distinct in Ky. and elsewhere (W), with concentration on relatively wet sites. Most records are from Appalachian regions; disjunct western records are old or uncertain (CHRI at CM; EDMO by Braun perhaps at US).