The member of the Evening Primrose family  sports yellow, one inch (2.5 cm) wide flowers, with four broad petals, 8 stamens, and a cross-shaped stigma. A slender calyx-like tube encloses the ovary below the petals. The lemon-scented flowers open near sunset and wilt in the sunshine (usually closing by noon). The coarse, hairy stem is often reddish tinged and reaches heights of 2 to 5 feet (61 to 152 cm). The lanceolate leaves measure 4 to 8 inches (10 to 20 cm) long with leaf margins that are slightly wavy. This plant is a common biennial in old fields and along roadsides. Flowers bloom from July to September.