Uses
Young roots can be eaten like a vegetable (with a peppery flavor), or the shoots can be eaten as a salad. Poultices containing O. biennis were at one time used to ease bruises and speed wound healing. One of the common names for Oenothera, "King's cureall", reflects the wide range of healing powers ascribed to this plant, although it should be noted that its efficacy for these purposes has not been demonstrated in clinical trials.
The mature seeds contain approximately 7-10% gamma-linolenic acid, a fatty acid. The oil also contains around 70% linoleic acid. The O. biennis seed oil is used to reduce the pains of premenstrual stress syndrome, however current scientific evidence does not support its general use for treatment of PMS. Evening Primrose Oil capsules have been used by pregnant woman orally in an effort to aid in cervical ripening, however this does not seem to shorten the length of pregnancy or labour. Some women also report inserting Evening Primrose Oil capsules vaginally during the third trimester of pregnancy, to assist cervical ripening. Gamma-linolenic acid also shows promise against breast cancer. Some side effects of using evening primrose oil are itching, sore throat and severe or extreme gassiness.
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