Oenothera is a genus of about 145 species of herbaceous flowering plants native to the Americas. It is the type genus of the family Onagraceae. Common names include evening primrose, suncups, and sundrops. They are not closely related to the true primroses (genus Primula).Certain Oenothera plants have edible parts. The roots of O. biennis are reportedly edible in young plants.