Evening-Primrose, Common

Oenothera biennis
This 3-6' plant may have a single stem or may be branched. The stem may be hairy or smooth and is sometimes reddish. The stem leaves are elliptical or lance-shaped and may have a few shallow teeth. The 1-2" flowers are in terminal clusters, open in the evening and close by noon. The 4 yellow petals are notched and overlap. The sepals are sweptback. The stamens are prominent and the stigma is wide and 4-part. . The blunt-tipped cylindrical seed capsule angles up nearly parallel to the stem. Blooms June-October in fields, roadsides, waste places.