Common Names: evening primrose oil, EPO Scientific Name: Oenothera biennis Background • Evening primrose is a flowering plant native to the Americas that also grows in Europe and parts of Asia. Its yellow blossoms open in the evening and close during daylight. The oil derived from its seeds is a source of omega-6 fatty acids, including gamma-linolenic acid (GLA). • Indigenous peoples traditionally used sap from its stems and leaves for minor skin issues like rashes, bruises, and surface