Oenothera is a genus of about 125 species of annual, biennial and perennial herbaceous flowering plants, native to North and South America. It is the type genus of the family Onagraceae, the Evening Primrose Family. Common names include evening-primrose, suncups, and sundrops. The species vary in size from small alpine plants 10 cm tall (e.g. O. acaulis from Chile), to vigorous lowland species growing to 3 m (e.g. O. stubbei from Mexico). The leaves form a basal rosette at ground level and spiral up to the flowering stems; the leaves are dentate or deeply lobed (pinnatifid)...