Oenothera biennis, the common evening-primrose,[3] is a species of flowering plant in the family Onagraceae, native to eastern and central North America, from Newfoundland west to Alberta, southeast to Florida, and southwest to Texas, and widely naturalized elsewhere in temperate and subtropical regions.

However, plants with annual life cycles are documented, and have been selected for under experimental conditions in environments with low competition.

In the second year, it grows up much taller, to around 1.6 metres (5.2 ft) tall, on a semi-woody stem, which then flowers and seeds.

[5][18] The evening primrose was introduced to Europe in the early 17th century as an ornamental plant in botanical gardens where its flowers are favored for nectar by pollinators, such as bees, and its seeds are food for birds.

[18] Anishinaabe tribes traditionally make tea from the evening primrose leaves for use as a dietary aid and to reduce fatigue.

[23] The Mayo Clinic stated there was no good evidence that it affected eczema, diabetic neuropathy or premenstrual syndrome.

[24] The American Cancer Society stated that there was little evidence for its effectiveness as an anti-cancer agent, for which it is sometimes promoted, and "neither GLA nor other GLA-rich supplements (such as evening primrose oil) have been convincingly shown to be useful in preventing or treating any other health conditions.

[5] The Mayo Clinic recommends caution in people with seizure disorders or mania, and by pregnant or breastfeeding women, and publishes a long list of possible side-effects.

[24] The whole plant and especially the leaves are traditionally boiled to tea by Anishinaabe tribes as an energy stimulant and to facilitate weight loss.

The evening primrose prefers sunny, and arid places with loamy soil and occurs below 700 metres (2,300 ft) above sea level.

The cultivation of evening primrose is thus suitable for no-till farming, but the plants require an intense mechanical weed control.

[18] A study has shown, that the irrigation with salt water could increase the oil yield and quality in evening primrose seeds.

[18] If the seeds are used for pharmaceutical purposes it is also important to grow the evening primrose without any pesticides to avoid any chemical residues.