Oenothera riparia Nuttall. Riverbank Evening-primrose. Phen: Jun-Jul. Hab: Freshwater tidal marshes and freshwater tidal swamp forests, non-tidal swamps, along channel margins, and especially on rises, stumps, fallen logs, and cypress knees. 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, S13; = n/a – Tat; = 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)

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Wetland Indicator Status:

• Atlantic and Gulf Coastal Plain: FACU (taxonomic split from wetland indicator species)
• Great Plains: FAC (taxonomic split from wetland indicator species)
• Midwest: FACU (taxonomic split from wetland indicator species)
• Northcentral & Northeast: FACU (taxonomic split from wetland indicator species)

Heliophily: 7