The oenothera (oh na /thera) genus contains about 120 species. These plants are mostly frost hardy and grow best in light soil in full sun. They are native to temperate regions in North and South America and include annuals, biennials and perennials.
The flowers appear in early summer and are short lived with four petals and a long basal tube. Most only release their perfume at night to attract nocturnal pollinators, hence the common name of evening primrose.
An oil can be extracted for medicinal purposes from the tiny seeds.
The common evening primrose is oenothera biennes, a large upright and hairy biennial with yellow flowers in tall spikes.
Oenothera fruticosa, known as sundrops, grows to about 3 feet with sunshine-yellow blooms.
Oenothera speciosa is a short lived perennial that forms clumps 18 - 24 inches tall with profuse pink-tinted-white blooms and small leaves that sometimes turn red.
Oenothera oderata is a perennial with fragrant yellow flowers that open at dusk.