| Oenothera refracta S. Watson, 1882 |
| Oenothera resicum Benavides, Kuethe, Ortiz-Alcaráz & León de la Luz, 2019 |
| Oenothera rosea L'Hér. ex Aiton, 1789 |
| Oenothera rubra Cav., 1797 |
| Oenothera serrulata Nutt., 1818 |
| Oenothera sinuata L., 1771 |
| Oenothera sinuosa W.L. Wagner & Hoch, 2007 |
| Oenothera speciosa Nutt., 1821 |
| Oenothera stubbei W. Dietr., P.H. Raven & W.L. Wagner, 1985 |
| Oenothera suffrutescens (Ser.) W.L. Wagner & Hoch, 2007 |
| Oenothera suffulta (Engelm. ex A. Gray) W.L. Wagner & Hoch, 2007 |
| Oenothera suffulta subsp. nealleyi (J.M. Coult.) W.L. Wagner & Hoch, 2007 |
| Oenothera suffulta subsp. suffulta (Engelm. ex A. Gray) W.L. Wagner & Hoch, 2007 |
| Oenothera tamrae W. Dietr. & W.L. Wagner, 1987 |
| Oenothera tetraptera Cav., 1796 |
| Oenothera texensis P.H. Raven & D.R. Parn., 1970 |
| Oenothera triloba Nutt., 1821 |
| Oenothera tubicula A. Gray, 1852 |
| Oenothera tubicula subsp. strigulosa (Towner) W.L. Wagner & Hoch, 2007 |
| Oenothera tubifera Ser., 1828 |