Common Evening Primrose, Oenothera biennis

Common Name: Common Evening Primrose

This plant is a member of the Onagraceae family. With a hairy stem, often purple-tinged, Oenothera biennis, more commonly known as Common Evening Primrose, is an erect, 1m - 1.5m biennial with leafy, branched stems from a basal rosette. The bright-yellow, four-petaled flowers, up to 2 inches across, open at night. These fragrant flowers occur in a many-flowered, terminal spike.

The flowers of this night-flowering biennial open in the evening and close by noon. The plant takes 2 years to complete its life cycle, with basal leaves becoming established the first year, and flowering occurring the second. Flowering time is June, July, August and September. The roots are edible, and the seeds are important as bird feed. Most of the evening-primroses have yellow flowers. Showy Evening-primrose (O. speciosa) has pink or white flowers.