This is concentrated in a broad zone from the Gulf Coastal Plain to the central Mississippi Valley to the Great Lakes region, with concentration in La., Ark., Mo., Ill., Mich. and N.Y. But it is listed as rare by Natural Heritage Programs in most states (NS), and should proably be considered globally declining to threatened (FNA 7). In Ky., the only secure populations may be in or near larger wetlands of the Mississippian Embayment. Records from the northern Bluegrass are 50-100 years old: in BOON (Nelson 1919) and KENT (PH; see also B). Although perhaps associated with relatively high pH, the species appears to be intolerant of turbid waters (Croft & Chow-Fraser 2007). Generic placement of this heterophyllous subaquatic plant remains unsettled; Neobeckia would be monotypic (FNA 7, Y, W). Rhizomes are lacking but stems often become decumbent, buried and rooted. Also, the species "is remarkable for its capacity to regenerate plants from tiny fragments of leaves, stems, and roots... [submersed] dissected leaves are usually detached in nature during late summer and fall" (Al-Shehbaz 1988b). The species is triploid (2n = 24) and does not generally produce viable seed (Les et al. 1995).