6190 - Evening Primrose: oenothera biennis, Biennial. Oil in seeds contains gammalinolenic acid (GLA), a precursor of prostaglandin E1. The latter is very active biologically regulating such functions as the vessel and immune systems. By supplementing the diet with GLA, one can bypass a blockage of prostaglandin E1 production caused by aging, poor diet, or alcoholism. Chronic complaints such as PMS disappear. Roots can be eaten as a vegetable; shoots as a salad.