The big-fruit evening primrose is punctuating the plantings in the Dry Meadow to great effect.
A native of the United States, Oenothera macrocarpa is one of approximately 125 species of evening primrose, which occur in North and South America. Species can be annual, biennial and perennial, and all occur on sunny sites, from mountainsides to deserts, and this is a valuable species for a dry, sunny, open site. Members of the genus have alternate leaves, and the four-petalled, tubular flowers can be saucer to trumpet-shaped; vary in colour from pink, white and yellow; and occur either individually in leaf axils, or in terminal racemes. As the common name evening primrose suggests, many flower from dusk until dawn. O. macrocarpa has a lax, open habit, with plants reaching 20cm in height, and up to 60cm across. In this species large, solitary, cup-shaped flowers remain open during the day, and are held on red-tinted stems bearing narrow leaves which have a distinct white midrib. This species occurs in North America, where it is pollinated by hawk moths. The origin of the generic name Oenothera is unclear, though in Greek it means ass-catcher, or wine-seeker, while macrocarpa means large-fruited. The genus belongs to the Onagraceae (willowherb or evening primrose family), which also contains Fuchsia, Epilobium and Clarkia.