Oenothera macrocarpa, commonly called Missouri evening primrose, is a sprawling, native plant which occurs on limestone glades and bluffs and rocky prairies in the Ozark region south of the Missouri River. Typically grows 6-12" tall and features very large (3-5" across), solitary, 4-petaled, mildly fragrant, bright yellow flowers which open for only one day (usually open late afternoon and remain open until the following morning). Flowers arise from leaf axils and are generally upward-facing, but sometimes rest on or touch the ground. Long spring to summer bloom period. Flowers are followed by somewhat unique, winged seed pods (2-3" long). Narrow, lance-shaped leaves. This species was formerly called (and is still often listed for sale as) Oenothera missouriensis.
Easily grown in average, dry to medium, well-drained soil in full sun. Tolerates poor and/or limey soils, drought and some light shade. Easily grown from seed and will self-seed under optimum growing conditions. Deer Resistant.
Specific epithet means large-fruited.There are no serious insect or disease problems. Root rot may occur in wet, poorly drained soils.
The species is attractive in border fronts or rock gardens. Also effective in wild gardens, meadows, cottage gardens or native plant gardens. A showy plant which can be grown in poor, dryish soils. They are pollinated by night-flying moths, such as the primrose moth (Schinia florida).
Photographs and Text adapted from: Missouri Botanic Garden