This widespread species of wetlands across south-central states has often been confused with brevior, normalis or other species; 2n = 68 or 70. Some colls. still need to be rechecked. A few colls. from FAYE and MADI (KY) are atypical (see also annotations of A.A. Reznicek), and they have suggested transitions to brevior or molesta; see notes under those species and FNA 23.