This is widespread in wetlands from southeastern states to Central America. It is an amphiploid (2n = 66), derived from robusta (2n = 34) and A. auriculata Willd. (2n = 32), which is more western and southern. The latter has been reported from Ky., but probably in error (M). See notes under robusta; more records may be transferred to robusta, following closer study. McFarland (1942) also reported A. koehnei Britt. (a segregate of the more tropical A. latifolia L.) from Ky., but probably in error (M),