Oenothera is a genus of about 160 species of herbaceous flowering plants native to the Americas. The genus includes the plants known as common evening primrose, narrow-leaved sundrops and white gaura. It is the type genus of the family Onagraceae. They are not closely related to the true primroses (genus Primula).
Description
The species vary in size from small alpine plants 10 centimeters tall, such as O. acaulis from Chile, to vigorous lowland species growing to around 3 meters talls, such as O. stubbei from Mexico. The leaves form a basal rosette at ground level and spiral up to the flowering stems. The blades are dentate or deeply lobed (pinnatifid). The flowers of many species open in the evening, hence the name "evening primrose". They may open in under a minute. Most species have yellow flowers, but some have white, purple, pink, or red. Most native desert species are white. Oenothera cespitosa, a species of western North America, produces white flowers that turn pink with age.
One of the most distinctive features of the flower is the stigma, which has four branches in an X shape.
