ABSTRACT
Didiplis diandra is a small shoreline aquatic plant scattered throughout eastern North America. In the Atlantic coast states from Virginia to Georgia it has been confused with other species that grow in similar habitats. Leaves of D. diandra are heterophyllous, submersed leaves average 15.4 mm long while emersed leaves average 6.3 mm long. A taxonomic key is presented to aid in identification of small shallow water and shoreline aquatic plants including members of the genera Callitriche, Crassula, Elatine and Ludwigia.