Oenothera biennis – Common Evening Primrose – Evening Primrose – Sundrops –

Description

Oenothera – Evening Primrose – Sundrops – There are about 125 species of annuals, biennials, and perennial, some with taproots or fibrous roots and a few with rhizomes or runners in this genus. They are mostly from North America, but widely naturalized elsewhere, in well drained, sunny sites, such as mountain slopes, although some are from deserts. They have upright or decumbent stems with alternate, more or less lance shaped, simple or pinnatifid, smooth edged or toothed, and occasionally basal rosettes of slightly larger leaves.   Evening primrose are grown for their short lived flowers, which are produced over long periods in summer, they are often fragrant, yellow, or less commonly red, pink or white and are large saucer to cup shaped, sometimes trumpet shaped. Each flower has a long tube and 4 petals, and is either solitary and axillary, or borne in terminal racemes. Individual flowers open at dawn or dusk, and fade quickly. Taller species are suitable for a sunny, mixed or herbaceous border, low growing ones are better for border edging. Grow in poor to moderately fertile, well drained, even stony soil, in full sun. Protect from excessive winter moisture. Divide in early spring or fall. Prone to leaf gall, downy mildew, rust, powdery mildew, Septoria leaf spot, and root rot may occur in wet soils. O. biennis – Common Evening Primrose – This fast growing, erect, hairy annual or biennial, usually grown as a biennial from Eastern North America and has also been naturalized in many other parts of the world grows 3-5′ feet tall and 2′ feet wide.   It produces large rosettes of oblong to lance shaped, shallowly toothed, slightly sticky, red veined, mid green leaves, 4-12″ long, and lance shaped stem leaves, to 6″ long. From summer to autumn it bears bowl shaped, fragrant flowers, to 2″ across, initially pale yellow, aging to dark golden yellow and opening in the evening and shriveling before noon, are held in leafy, spike like racemes. Seeds are used to produce evening primrose oil. Zones 4-8