Oenothera riparia Nuttall. Phen: Jun-Jul. Hab: Freshwater tidal marshes and freshwater tidal swamp forests, non-tidal swamps, along channel margins. Dist: Se. VA south to se. NC and e. SC. Present in the freshwater tidal portions of the Waccamaw, Northeast Cape Fear, Black, Greater Pee Dee, Cape Fear, Scuppernong, and Alligator rivers. Gramling et al. (2018) discuss the species' occurrence along the Edisto River (Charleston and Colleton counties, SC).
Origin/Endemic status: Endemic
Taxonomy Comments: Distinct from O. fruticosa.
Synonymy: = FNA10, K4, Va, Wagner, Hoch, & Raven (2007); = Kneiffia riparia (Nutt.) Small – S; = Oenothera tetragona Roth ssp. glauca (Michx.) Munz var. riparia (Nutt.) Munz – Munz (1965); < Oenothera fruticosa L. – C, RAB; < Oenothera fruticosa L. ssp. fruticosa – K1, K3, Straley (1977)