[7] The large flowers, up to 13 cm (5 in) across, are cup shaped with four petals, canary yellow, and have a mild fragrance.

The specific epithet macrocarpa is also from the Greek, meaning "large fruited".

[12] Oenothera macrocarpa is native to Arkansas, Illinois, Kansas, Missouri, Nebraska, Oklahoma, Tennessee, Texas, and northeast Mexico.

[13] Habitats include limestone outcrops, glades, bluffs, rocky prairies, quarries, and roadsides.

[14][15] It is suitable as a groundcover in poor, stony soil which does not become waterlogged in winter, in full sun.