This is widespread in lakes and rivers of North and Central America. It is known from scattered locations across Ky., but generally not in eutrophic waters. Although the species has several cytotypes and described varieties, plants of east central states are reportedly the typical variety, with 2n = 24 (FNA 22). Despite earlier reports, that number is predominant among other eastern species in this "vegetatively plastic" genus (Cr), but hybrids are not documented.