Oenothera biennis

Botanical Name : Oenothera biennis
Family: Onagraceae
Genus: Oenothera
Species: O. biennis
Kingdom: Plantae
Order: Myrtales

Synonym: Tree Primrose.  It is also known as Weedy evening-primrose, German rampion, hog weed, King’s cure-all, and fever-plant

Common Names : Tree Primrose, Common evening primrose, Evening star, or Sun drop

Habitat: Oenothera biennis though originally a native of North Arnerica, was imported first into Italy and has been carried all over Europe, being often naturalized on river-banks and other sandy places in Western Europe. It is often cultivated in English gardens, and is apparently fully naturalized in Lancashire and some other counties of England, having been first a garden escape.

Dscription:
The root is biennial, fusiform and fibrous, yellowish on the outside and white within. The first year, many obtuse leaves are produced, which spread flat on the ground. From among these in the second year, the more or less hairy stems arise and grow to a height of 3 or 4 feet. The later leaves are 3 to 5 inches long, 1 inch or more wide, pointed, with nearly entire margins and covered with short hairs. The flowers are produced all along the stalks, on axillary branches and in a terminating spike, often leafy at the base. The uppermost flowers come out first in June. The stalks keep continually advancing in height, and there is a constant succession of flowers till late in the autumn, making this one of the showiest of our hardy garden plants, if placed in large masses. The flowers are of a fine, yellow colour, large and delicately fragrant, and usually open between six and seven o’clock in the evening, hence the name of Evening Primrose. From a horticultural point of view, the variety grandiflora or Lamarkiana should always be preferred to the ordinary kind, as the flowers are larger and of a finer colour, having a fine effect in large masses, and being well suited for the wild garden.
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Oenothera biennis has a life span of two years (biennial) growing to 30–150 cm (12–59 in) tall. The leaves are lanceolate, 5–20 cm (2.0–7.9 in) long and 1–2.5 cm (0.39–0.98 in) broad, produced in a tight rosette the first year, and spirally on a stem the second year.

Blooming lasts from late spring to late summer. The flowers are hermaphrodite, produced on a tall spike and only last until the following noon. They open visibly fast every evening producing an interesting spectacle, hence the name “evening primrose.”

The blooms are yellow, 2.5–5 cm (0.98–1.97 in) diameter, with four bilobed petals. The flower structure has an invisible to the naked eye bright nectar guide pattern. This pattern is apparent under ultraviolet light and visible to its pollinators, moths, butterflies, and bees.

The fruit is a capsule 2–4 cm (0.79–1.57 in) long and 4–6 mm (0.16–0.24 in) broad, containing numerous 1–2 mm (0.039–0.079 in) long seeds, released when the capsule splits into four sections at maturity.

Cultivation: The Evening Primrose will thrive in almost any soil or situation, being perfectly hardy. It flourishes best in fairly good sandy soil and in a warm sunny position.

Sow the seeds an inch deep in a shady position out-doors in April, transplanting the seedlings when 1 inch high, 3 inches apart each way in sunny borders. Keep them free from weeds, and in September or the following March, transplant them again into the flowering positions. As the roots strike deep into the ground, care should be taken not to break them in removing.

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Seeds may also be sown in cold frames in autumn for blooming the following year.

If the plants are once introduced and the seeds permitted to scatter, there will be a supply of plants without any special care.

Medicinal Uses:
Parts Used: Bark and leaves. The bark is peeled from the flower-stems and dried in the same manner as the leaves, which are collected in the second year, when the flowerstalk has made its appearance.

Astringent and sedative. The drug extracted from this plant, though not in very general use, has been tested in various directions, and has been employed with success in the treatment of gastro-intestinal disorders of a functional origin, asthma and whooping cough.

It has proved of service in dyspepsia, torpor of the liver, and in certain female complaints, such as pelvic fullness.

Its leaves are edible and traditionally were used as a leaf vegetable.

Evening primrose is sometimes used to treat eczema. Natural Standard has given evening primrose oil a “B” score for the treatment of eczema; meaning there is good scientific evidence supporting its use Template:Http://www.naturalstandard.com/databases/herbssupplements/primrose.asp. The symptoms of eczema can be exacerbated due to scratching and drying out the skin. Evening primrose oil contains linoleic acid, which is the primary oil found in the stratum corneum.{{Citation Angelo, Giana. “Essential Fatty Acids and Skin Health.” Linus Pauling Institute: Micronutrient Information Center. Oregon State University, Feb. 2012. Web. 30 Nov. 2012. .}}. Supplementation with EPO may help rehydrate skin that has been scratched due to eczema. Furthermore, gamma-linoleic acid is metabolized into anti-inflammatory compounds, which may contribute to its ability to provide symptomatic relief in eczema. Most studies evaluating the effectiveness of EPO used 4 capsules of standardized extract (~1600 mg of evening primrose oil TOTAL) dosed by mouth twice daily for up to 12 weeks.

Evening Primrose Oil has been shown to slightly reduce blood pressure, can increase clotting time (use with caution if you take warfarin or aspirin), and should not be used by epileptics as it lowers the seizure threshold. Safety has not been evaluated in pregnant or nursing women.

Disclaimer:
The information presented herein is intended for educational purposes only. Individual results may vary, and before using any supplements, it is always advisable to consult with your own health care provider.

Resources:
http://en.wikipedia.org/wiki/Oenothera_biennis
http://www.botanical.com/botanical/mgmh/p/primro70.html

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