- Family Onagraceae
- Oenothera biennis
- Common/Wild/Field Evening Primrose, Tree Primrose, Fever Plant, King’s Cureall, Large Rampion, Night Willowherb, Scabish, Scurvish, Sun Drop, Rose of Mexico
- Spanish: Yerba del Golpe, Flor de San Juan
- Maya: Chan-xmuk
- Be aware that EPO (evening primrose oil) has the potential to lower the seizure threshold and those taking seizure medications should be carefully monitored.
Native to North America, the herb is now commonly found in many temperate zones around the world, thriving in open areas, especially dunes and sandy soil. This biennial herb produces only leaves the first year and bright yellow flowers and seeds the second year. It grows to about eight inches and has red blotches on the stem, crinkled lance-shaped leaves, four-petaled flowers, and elongated seed capsules. Today, it is commercially grown for its seed oil.
Its Spanish name, yerbe del golpe, means "herb for bruises", a name given to many bruise-healing plants. Most often though, it refers to some species of the primrose.
Pliny used the botanical name Oenothera for a plant which is now unknown that reputedly produced sleep when drunk in wine. The species name, biennis, means "lasting two years," indicating that the plant is a biennial.
An 1830 herbal stated that the leaves were effective for wounds.
Native Americans used the plant for many of the same reasons as it is used today.
*The tiny seeds were used as an unspecified medicine by the Forest Potawatomis.
*The Flambeau Ojibwas used the whole plant, soaked in warm water, to make a poultice for bruises.
*The Omahas used one species (O. rhombipetala) in poultices, while the Blackfeet used another (O. caespitosa) for swellings and sores to reduce inflammation.
*The Kayenta Navahos applied O. caespitosa to correct a prolapsed uterus. They also made a dusting powder from the flowers to relieve soreness caused by chafing.
*The Iroquois used a topical wash to treat hemorrhoids and a tea as a remedy for coughs and colds, depression, and digestive complaints. In poultices, it was used to treat bruises and boils as well as skin rashes and other irritations.
- digestive aid
- lowers blood pressure
- essential fatty acids (60-80% linoleic acid and 8-15% linolenic or GLA)
- 9% oleic acid (a non-essential fatty acid)
Leaves, stem bark, flowers, root, seed oil
The seed oil contains the essential fatty acids vital to the needs of the body. The first metabolic conversion of linoleic acid (LA) to prostaglandins (hormone-like fatty acid derivatives) is the transformation to gamma linolenic acid (GLA). This conversion is blocked by excessive saturated fatty acids (trans-fatty acids in processed oils, alcohol, and in zinc deficiencies). The process is also slowed during diabetes and ageing. Dietary GLA can bypass this blocked step. Furthermore, it is metabolized to a type of prostaglandin (PGE1) that inhibits the formation of pro-inflammatory prostaglandins, thus helping to reduce allergy symptoms and atopic eczema in some cases. Both LA and GLA seem to have other diverse effects, including boosting the immune system, reducing symptoms of premenstrual syndrome, lowering blood cholesterol, and slowing blood clotting.
All the plant has been used in the treatment of whooping cough, asthma, and digestive problems.
Poultices made from infusions can be applied to rheumatic areas.
Mexicans make a poultice of the leaves to treat burns, bruises, sore throat, and chest congestion and infusions of the flowers are taken to treat kidney problems and menstrual cramps.
Internal use of the EPO has proven effective for cases of atopic eczema, premenstrual syndrome, alcoholism, elevated cholesterol levels, Sjogren's syndrome, mild hypertension, scleroderma, multiple sclerosis, rheumatoid arthritis, and especially for intermittent cladication and other circulatory problems.
Externally, the oil is used to heal skin disorders. Capsules are used in Germany to treat symptoms of atopic eczema.
Since the oil contains both omega 3 and omega 6 essential fatty acids, it is vital in the diet as a preventative for many diseases. However, true to form, the FDA has given the oil "disapproving attention," claiming it is "unaware of any evidence to establish safely and effectiveness for such claims."