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Oenothera Speciosa: The Captivating Pink Ladies of Your Garden

The Oenothera speciosa, also known as the Showy Evening Primrose or Pink Ladies, is a perennial herb within the Onagraceae family. It has a large taproot that can reach a diameter of 1.5 cm. Its stems often grow in clusters and are known to bloom as the moon appears in the evening and wilt as […]

The Oenothera speciosa, also known as the Showy Evening Primrose or Pink Ladies, is a perennial herb within the Onagraceae family. It has a large taproot that can reach a diameter of 1.5 cm.

Its stems often grow in clusters and are known to bloom as the moon appears in the evening and wilt as the dawn arrives, hence the name Evening Primrose.

However, the Showy Evening Primrose also blooms during the day. Its cup-shaped flowers attract fluttering butterflies, adding to its beauty. Cluster cultivation creates a unique natural garden atmosphere.

I. Morphological Characteristics

Oenothera speciosa

The Showy Evening Primrose is a perennial herb with a large main root up to 1.5 cm in diameter. The stems often cluster, rising 30-55 cm in length with many branches, covered in curved soft hairs. The base of the plant is often purple-red.

Its basal leaves are closely attached to the ground, oblong-lanceolate, 1.5-4 cm long, 1-1.5 cm wide, tapering or suddenly narrowing from the middle and irregularly deeply lobed down to the stalk.

The stem leaves are gray-green, lanceolate or oblong-ovate, 3-6 cm long and 1-2.2 cm wide. The top of the stem has a blunt sharp tip, while the middle to upper part is sharp to gradually pointed.

The base is broadly wedge-shaped and suddenly tapers down to the stalk. The base is finely feathered, with 6-8 pairs of veins on both sides covered with curved soft hair. The flowers are single, born at the top of the stem and branches, opening near sunrise.

The buds are green, conical-cylindrical, 1.5-2.2 cm long, and the calyx teeth at the top are tightly contracted into a beak. The flower tube is pink, 5-8 mm long, covered with curved soft hair.

The petals are pink to purple-red, broadly ovate, 6-9 mm long, 3-4 mm wide, bluntly rounded at the top, with 4-5 pairs of feathered veins.

The filaments are white to light purple-red, 5-7 mm long. The anthers are pink to yellow, oblong-linear, about 3 mm long, with about 50% of the pollen developed.

The ovary is narrowly elliptical during flowering, about 8 mm long, with a total pedicel length of 6-10 mm, densely covered with curved soft hair. The pistil is white, 8-12 mm long, with the part protruding from the flower tube being 4-5 mm long.

Oenothera speciosa

The stigma is red, surrounded by anthers, with the lobes about 2 mm long, and the pollen is directly delivered to the lobes. The capsule is rod-shaped, 8-10 mm long, 3-4 mm in diameter, with 4 longitudinal wings, ribs between the wings, and a short beak at the top.

The fruit stalk is 6-12 mm long. There are numerous seeds per chamber, nearly horizontally clustered, oblong-ovate, 0.7-0.9 mm long, 0.3-0.5 mm in diameter. The flowering period is from April to November, and the fruiting period is from September to December.

The root is cylindrical, the stem is erect, the seedlings are rosette-shaped, the base has red long hairs, the leaves are alternate, the stem has a lower part with a handle, and the upper leaves are handleless.

The leaf blade is oblong or lanceolate, the edge has sparse fine serrations, and both sides are covered with white soft hair. The flowers are single, born at the end of the branch axil, arranged in a loose spike, with a long calyx tube.

The flowers are white to pink, the flower diameter is over 8 cm, and the flowers continue to bloom from May to October. The height range is 50-80 cm.

The Showy Evening Primrose (Oenothera speciosa) is a low ground cover plant, strong growth, very drought-tolerant, and has a wide adaptation range.

The flowering period is from April to October, the flowers are bright pink, the flowers are large, and the flower quantity is high. It has a very strong ability to self-seed. It can be widely used for landscape decoration, or it can be cultivated as a flower bed plant.

It can be directly sown in the open field, or it can be produced and sold by seedling nurseries as ground cover plants. It can be sown in spring, summer, and autumn. It can also be sown in a protected ground for transplanting in winter.

It opens every evening until it wilts near noon the next day. It is not tolerant to severe cold, and it can overwinter in the wind in the south of the Yangtze River. It can be propagated by autumn sowing. Its growth habits are: light-loving, cold-resistant, and avoids waterlogging.

The plant is 1.5 to 2.2 meters tall, with a cylindrical root and an erect stem with branches. The seedlings are rosette-shaped, and the base has red long hairs.

The leaves are alternate, the lower stems have handles, and the upper leaves are nearly handleless; the leaf blade is oblong, lanceolate, 6-9 cm long, 1.5-3 cm wide, the edge has sparse fine serrations, and both sides are covered with white soft hair.

The flowers are single, born at the end of the branch axil, arranged in a loose spike, the calyx tube is slender, the top is 4-lobed, the lobes are reflexed; there are 4 petals, yellow, there are 8 stamens, 4 of which are opposite to the petals.

There is 1 pistil, and the stigma is split. The capsule is cylindrical, the top is pointed, the outer end is pointed, the outside is covered with white long hair, and it naturally splits when mature. The seeds are small, brownish-black, and irregularly triangular.

II. Growing Environment

The plant is native to the southern region of Texas, USA, extending to Mexico. It is also found in the warm temperate mountain regions of southwestern USA, Central America, and South America. It has been cultivated in Eurasia and South Africa and has become wild.

It’s highly adaptable, acid and drought resistant, and doesn’t require specific soil conditions. It can grow in neutral, slightly alkaline, or slightly acidic soil that drains well. If the soil is too wet, the roots are prone to disease.

It thrives in semi-shaded areas along ditches in arid grasslands at altitudes between 1000-2000 meters.

III. Distribution Range

South America

IV. Main Value

The roots are used medicinally for their anti-inflammatory and blood pressure lowering effects.

Evening primrose oil, extracted from this plant, is a significant nutritional medicine discovered in this century. The seeds contain 20-30% oil, 70% of which is linoleic acid, and 8-9% is the essential γ-linolenic acid (GLA).

Evening primrose oil can treat an array of diseases, regulate lipids in the blood, and has shown remarkable effectiveness against coronary thrombosis, atherosclerosis, and cerebral thrombosis caused by high cholesterol and high blood lipids.

It’s also used to treat multiple sclerosis, diabetes, obesity, rheumatoid arthritis, and schizophrenia. Laboratory studies have shown its potential to inhibit cancer cell growth.

Clinically, evening primrose oil is used to prevent cardiovascular blockages and lower cholesterol, making it a potent remedy for cardiovascular diseases. The flowers of evening primrose can be used to extract aromatic essences.

Evening primrose oil contains a large amount of essential fatty acid – γ-linolenic acid (GLA), which has ten times the activity of linoleic acid. The earliest diseases treated using evening primrose were multiple sclerosis, atopic dermatitis, and rheumatoid arthritis.

Evening primrose is native to the Americas. The indigenous people discovered its medicinal value hundreds of years ago. They used the whole plant, soaked in warm water, to make a paste to treat contusions and used it as a poultice on the skin to treat skin trauma and inflammation.

In the 18th century, seeds were transported to England on cotton ships, marking the beginning of the plant’s widespread cultivation in Europe.

Many scientists and physicians have since undertaken research on evening primrose and used it to treat multiple sclerosis, atopic dermatitis, and rheumatoid arthritis.

The two main components of evening primrose are essential fatty acids and GLA. These two ingredients are pivotal to the plant’s medical and health benefits. Essential fatty acids are necessary for the human body but cannot be synthesized by the body; they must be obtained from the diet.

They provide energy, maintain body temperature, protect tissues and organs, and are an indispensable constituent of cells and tissues in the body. They are also used by the body to synthesize important prostaglandins and hormones.

A deficiency of essential fatty acids can lead to hair loss, slow wound healing, significantly impaired reproductive function, decreased immune function, and increased susceptibility to virus and bacterial infections.

Another constituent of evening primrose that has garnered attention in the medical field is prostaglandin. This substance was first discovered in semen by a Swiss scientist in 1930 and was named “prostaglandin”.

It was later found to be ubiquitous in the human body, with many different combinations playing different roles within the body. For instance, steroids are often used in medicine for their anti-inflammatory and anti-allergic properties.

However, steroids have significant side effects and suppress both inflammatory and anti-inflammatory prostaglandins. Evening primrose, on the other hand, can synthesize and increase anti-inflammatory prostaglandins, but it suppresses inflammatory prostaglandins.

This unique biological activity makes evening primrose a smarter alternative with less potential side effects. This explains why evening primrose may be a boon for patients with allergic constitutions.

Patients with premenstrual syndrome (PMS) often lack essential fatty acids (EFAs) needed for prostaglandin synthesis and have elevated levels of estrogen and prolactin hormones, leading to various physical and psychological imbalances and discomforts.

The most common symptoms include physical discomfort such as breast swelling, breast pain, headaches, heaviness in the head, fever, and psychological symptoms such as drowsiness, cravings, irritability, depression, and emotional instability.

Evening primrose is an important source of various hormones, prostaglandins, and other endocrine substances in the body.

Supplementing with evening primrose indirectly maintains the balance of these endocrine substances, making it beneficial for women suffering from PMS, one of the most distressing female syndromes.

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Founder of FlowersLib

Peggie was once a high school mathematics teacher, but she set aside her chalkboard and textbooks to follow her lifelong passion for flowers. After years of dedication and learning, she not only established a thriving flower shop but also founded this blog, “Flowers Library”. If you have any questions or wish to learn more about flowers, feel free to contact Peggie.

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