Oenothera fruticosa

Oenothera fruticosa, the narrowleaf evening primrose or narrow-leaved sundrops, is a species of flowering plant in the evening primrose family. It is native to much of eastern North America, where it is found in a variety of open habitats, including dry woodlands, rock outcrops and moist savannas. It is an erect herbaceous perennial growing to 20–90 cm (8–35 in) tall, with alternative, simple, entire or slightly toothed leaves. The saucer- or cup-shaped yellow flowers, 2.5–5 cm (1–2 in) in diameter, appear in late spring and summer. The fruit is a capsule that is strongly 4-angled or winged and shaped like a club. Many varieties have been named, but the infraspecific taxonomy of this species is still in an unresolved state....read more on Wikipedia.