This stoloniferous tetraploid (2n = 32) of "wet meadows and swales" (W) is largely midwestern. It is uncommon to rare across much of its southern and eastern range, with only sporadic reports from Ark., Ala., Tenn., Va., W.Va., Pa. and New England (Ch, K, W). In Ky., the species is virtually restricted to counties bordering the Ohio Rv. A holotype is at KY; the species was discovered by H.A. Griswold in "wetlands around Louisville [JEFF], where it occurs in great abundance" (Short & Peter 1835). Reports from FAYE (K) are spurious, due to Short's residence in "Lexington" (see coll. at GH). Most records are from downstream of JEFF, but there appear to have been few records since the 1980s. In JEFF itself, there have been no records since Short's time. The only records upstream of JEFF in Ky, are colls. at KNK from BOON (pond inland from Aurora Ferry in 1977) and from CAMP (Silver Grove, near ballfield and N of St Anns Convent in the 1990s). Two related southeastern species can be expected in Ky. (F, J, K): the diploid L. microcarpa Michx. (usually on base-rich soils), and the "polymorphic" tetraploid L. sphaerocarpa Ell. (usually on sandy/peaty soils); see W for a detailed key. Both are most common on the Coastal Plain, but there are scattered records north to Tenn., and sphaerocarpa occurs around the southern side of Lake Michigan.