Evening primrose is a general name given to over a hundred related plants in the evening primrose family, Onagraceae, all of which have flowers that open in the evening. The common evening primrose, sometimes called the evening star, Oenothera biennis, is a biennial herbaceous plant native to the Americas.
The first year growth results in a basal rosette of leaves graduating from larger older leaves at the base to smaller younger leaves on top. The second year a hairy flower stalk rises up two to five feet tall from the center of the rosette that has overwintered. Numerous lance-shaped leaves are crowded on the substantial stalk that terminates with many flowers.
The yellow flowers have four large, simple petals. As the name suggests the flowers open up at evening time and wilt by the following day. A unique feature of the evening primrose is the X-shaped stigma that has four branches which form a cross. Stamens are also yellow and point downward. The blooming period is from late spring to late summer.
The evening primrose is a pioneer type plant that will grow in barren soil and disturbed areas. It can be found in old fields, waste areas, the edges of fields and along highways and railways.
The tap-roots are eaten as a root vegetable. The roots are pulled up, peeled, boiled and enjoyed for their peppery flavor. The pungency of the root varies with the time of year and seems at its height in the fall. Shoots are eaten fresh in salads in the spring.
Poultices of fresh leaves have been used for centuries to treat bruises and wounds. Although modern science has not verified the efficacy of such care, it was once believed that evening primrose could treat many maladies. It was even given the nickname ‘Kings cureall’ and it’s still used today for a number of maladies. An infusion or herbal tea is known to be astringent with sedative and pain-killing properties. It can be used as an anti-anxiety aid or to relieve symptoms of premenstrual syndrome.
Evening primrose oil is a nutrient-rich oil that is prescribed by the National Health Service in England for arthritis, especially rheumatoid arthritis. There is also evidence that it can reduce high blood pressure and high cholesterol. These effects are most likely due to the high content of gamma linoleic acid, an essential polyunsaturated fatty acid that our bodies use to make prostaglandins, which is a class of vital hormones. Capsules of evening primrose oil are available at most health food stores.