The narrowleaf evening primrose (Oenothera fruticosa) belongs to Onagraceae (the Evening primrose family). It is a perennial herb that is native to much of eastern North America. This herb grows in fields, meadows, open woods and roadsides, and can reach 30-90 cm in height. The basal leaves are ovate, and the cauline leaves are lanceolate to ovate with toothed edges. The racemes are borne at the tips of the branches, and the cup shaped, four-petaled, yellow flowers bloom in spring to summer. The flowers open in the morning and fade by midday, but the blooms continue for several weeks.