Oenothera villosa

Oenothera villosa
Close-up of flower
Habit

Secure  (NatureServe)[1]
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Myrtales
Family: Onagraceae
Genus: Oenothera
Species:
O. villosa
Binomial name
Oenothera villosa
[2]
  • O. v. subsp. strigosa
  • O. v. subsp. villosa
Synonyms[3][4]
List
    • Oenothera albinervis
    • Oenothera baurii
    • Oenothera canovertex
    • Oenothera canovirens
    • Oenothera cheradophila
    • Oenothera cockerellii
    • Oenothera depressa
    • Oenothera erosa
    • Oenothera hungarica
    • Oenothera prasina
    • Oenothera procera
    • Oenothera renneri
    • Oenothera rydbergii
    • Oenothera scandinavica
    • Oenothera strigosa
    • Oenothera subulifera
    • Oenothera velutinifolia
    • Onagra cockerellii
    • Onagra depressa
    • Onagra erosa
    • Onagra hungarica
    • Onagra lehmanniana
    • Onagra strigosa
    • Usoricum strigosum

Oenothera villosa, the hairy evening primrose, is a species of flowering plant in the family Onagraceae.[5] It is native to nearly all of the United States (except Hawaii, Alaska, Louisiana, Florida, and South Carolina), and to all Canadian provinces and the Northwest Territories. It has been introduced to cool and cold-temperate regions worldwide.[2] An erect biennial reaching 3–6 feet (0.91–1.83 m), it is typically found in open areas and disturbed situations.[5]

Description

This plant is a taproot dicotyledon (two stem leaves) biennial that has a red stem and is strigillose[6]. This term means hairy. In this Scenario, the plant is covered in trichome hairs. The hairs are considered erect. This means that they stick straight out from the stem, not in a curled manner. The leaves are usually green in color and can have fully denticulate margins or part entire (smooth edges), part denticulate margins. in rarer scenarios the leaves can have moderate dentate margins. This all means that the leaves usually have small teeth on their edges, or have parts of their leaves of small-toothed edges. Also the rare moderate dentate margins means that sometimes a plant can be found with somewhat larger teeth on its leaf borders.

The flowers inflorescent head, or the whole flower part of the plant is in the open position. The shoot growing structure called the apex is of the obtuse type. The plant has fruit capsules that do not measure any longer than the plants shoot internodes. This means that the fruit capsules are not longer than the spacings between the plants leaf nodes. The plants campanuate (bell shaped) yellow flowers have red stripes on the outer part of the flowers, so if someone views the flowers from the sides, not staring into the flowers, they appear as yellow, and painted with red stripes. The inside of the flowers are all yellow. The flowers are arranged into a terminal spike. This means that the flowers grow from the crown, which is the middle of the plant. These flowers bloom in the summer months in the United States which is from June through September. The plant has lanceolate leaves meaning sword shaped and have sinuate lobes which means the leaf lobes have a bending wavy pattern on their lobes. The leaves are mildly to moderately covered with hairs on their surfaces, front and back. The leaves sometimes have a coating of wax on their edges. The leaves measure 2.5 to 10 cm long or 1-4 inches. The herbaceous branches are covered in these fine hairs also. The yellow striped flowers measure 1.5- 3.5 cm in width or around 0.5 inches to 1 inch. [7] This plant has cylindrical seed pods (capsules) that are 1.3 to 3 cm (0.5-1.3 inches) long. These pods are thick at the base. The seeds are very small being only 1.3 to 1.5 mm long. The seeds are self-pollinating. This plant can usually reach a height of around 3-5 feet ( can reach 6 or 7) according to some other sources)[8]and can be found in waste lands, disturbed areas, and alongside roads etc. The plant can be found in almost all of the U.S states except a couple extreme cold and hot/humid states. A thing to state is that some of my sources come from a species called Oenothera biennis which is in the same family and order, this is a subspecies of this plant with a few differences such as the hair (trichomes) on the stems, but most of the height and flower characteristics are very similar.

Taxonomy

Oenothera villosa was given its scientific name by Carl Peter Thunberg in 1794. It is classified in the genus Oenothera as part of the Onagraceae family. It has two accepted subspecies:[2]

  • Oenothera villosa subsp. strigosa (Rydb.) W.Dietr. & P.H.Raven – western and central North America, and introduced to central Europe[3]
  • Oenothera villosa subsp. villosa – central and eastern North America, and introduced worldwide[4]

Oenothera villosa has 48 synonyms of its two subspecies including 24 species.[3][4]

Table of Synonyms[3][4]
Name Year Rank Synonym of: Notes
Oenothera albinervis R.R.Gates 1936 species subsp. villosa = het.
Oenothera baurii Boedijn 1924 species subsp. villosa = het.
Oenothera biennis subsp. baurii (Boedijn) Tischler 1950 subspecies subsp. villosa = het.
Oenothera biennis var. canescens Torr. & A.Gray 1840 variety subsp. villosa = het.
Oenothera biennis var. strigosa (Rydb.) Cronquist 1992 variety subsp. strigosa ≡ hom.
Oenothera canovertex Hudziok 1968 species subsp. villosa = het.
Oenothera canovirens E.S.Steele 1911 species subsp. villosa = het.
Oenothera cheradophila Bartlett 1907 species subsp. strigosa = het.
Oenothera cockerellii Bartlett ex de Vries 1913 species subsp. villosa = het.
Oenothera communis proles erosa (Lehm.) H.Lév. 1909 proles subsp. villosa = het.
Oenothera depressa Greene 1891 species subsp. villosa = het.
Oenothera depressa f. angustifolia Rostański 1965 form subsp. villosa = het.
Oenothera depressa f. latibracteata Rostański 1965 form subsp. villosa = het.
Oenothera erosa Lehm. 1828 species subsp. villosa = het.
Oenothera hookeri var. parviflora R.R.Gates 1915 variety subsp. villosa = het.
Oenothera hungarica (Borbás) Borbás 1903 species subsp. villosa = het.
Oenothera muricata var. canescens (Torr. & A.Gray) B.L.Rob. 1908 variety subsp. villosa = het.
Oenothera muricata f. hungarica (Borbás) Jáv. 1924 form subsp. villosa = het.
Oenothera parviflora var. canescens (Torr. & A.Gray) Farw. 1923 variety subsp. villosa = het.
Oenothera prasina Bartlett 1914 species subsp. strigosa = het., nom. nud.
Oenothera procera Wooton & Standl. 1913 species subsp. strigosa = het.
Oenothera renneri H.Scholz 1956 species subsp. villosa = het.
Oenothera renneri f. mollis Renner ex Rostański 1965 form subsp. villosa = het.
Oenothera rydbergii House 1921 species subsp. strigosa ≡ hom., nom. superfl.
Oenothera scandinavica Rostański 2007 species subsp. villosa = het.
Oenothera strigosa (Rydb.) Mack. & Bush 1902 species subsp. strigosa ≡ hom.
Oenothera strigosa var. albinervis (R.R.Gates) R.R.Gates 1957 variety subsp. villosa = het.
Oenothera strigosa subsp. canovirens (E.S.Steele) Munz 1965 subspecies subsp. villosa = het.
Oenothera strigosa subsp. cheradophila (Bartlett) Munz 1965 subspecies subsp. strigosa = het.
Oenothera strigosa var. cheradophila (Bartlett) R.R.Gates 1957 variety subsp. strigosa = het.
Oenothera strigosa var. cockerellii (Bartlett ex de Vries) R.R.Gates 1957 variety subsp. villosa = het.
Oenothera strigosa var. depressa (Greene) R.R.Gates 1958 variety subsp. villosa = het.
Oenothera strigosa subsp. hungarica (Borbás) Á.Löve & D.Löve 1961 subspecies subsp. villosa = het.
Oenothera strigosa var. procera (Wooton & Standl.) R.R.Gates 1957 variety subsp. strigosa = het.
Oenothera strigosa var. subulifera (Rydb.) R.R.Gates 1957 variety subsp. strigosa = het.
Oenothera subulifera (Rydb.) Rydb. 1913 species subsp. strigosa = het.
Oenothera velutinifolia Hudziok 1968 species subsp. villosa = het.
Oenothera villosa subsp. cheradophila (Bartlett) W.Dietr. & P.H.Raven 1976 subspecies subsp. strigosa = het.
Oenothera villosa var. strigosa (Rydb.) Dorn 1988 variety subsp. strigosa ≡ hom.
Onagra biennis var. strigosa (Rydb.) Piper 1901 variety subsp. strigosa ≡ hom.
Onagra cockerellii (Bartlett ex de Vries) de Vries 1913 species subsp. villosa = het.
Onagra depressa (Greene) Small 1896 species subsp. villosa = het.
Onagra erosa (Lehm.) Spach 1835 species subsp. villosa = het.
Onagra hungarica Borbás 1902 species subsp. villosa = het.
Onagra lehmanniana Spach 1835 species subsp. villosa = het.
Onagra strigosa Rydb. 1900 species subsp. strigosa ≡ hom.
Onagra strigosa var. subulata Rydb. 1900 variety subsp. strigosa = het.
Usoricum strigosum (Rydb.) Lunell 1916 species subsp. strigosa ≡ hom.
Notes: ≡ homotypic synonym; = heterotypic synonym

Uses

This plant is not as common for use as some other garden or culinary plants, but it has some notable uses. A few people have planted Oenothera Villosa in gardens. This plant can be used to attract butterflies (lepidopterans) and other pollinating insects/birds. The plant has a chemical compound omega fatty-acid called Gamma Linolenic Acid (GLA) That is found in the oil it contains called EPO or (Evening Primrose Oil) This oil is from a few of the closely related primrose plants including the Evening hairy primrose is thought to be an ingredient that is active in some therapeutic medicine. This oil is found in the seeds of this primrose plant. The oil is being used to treat some conditions/disorders that can be targeted by using these helpful omega fatty acids found in the oil. However, the accuracy and efficacy of this oil actually relieving and treating some of these conditions is still being debated among medical people as of the 2007 publishing of this source.[9]

some treatment uses of this oil (EPO) are its use in Assistive Reproductive health Technologies and medicine. This oil is being used to treat certain reproductive diseases/conditions, such as female breast inflammation, Euteral diabetes, and other inflammation ,and menopause/menstrual disorders. Some women take medicine with this oil in the medicine's contents before birth to help with reproductive qualities, and some have not experienced any harmful effects from its use[10]

This oil is prescribed for these illnesses due to its potential benefits in this field, so this is not 100 percent proven to help with these conditions either however.

References

  1. ^ NatureServe (5 September 2025). "Oenothera villosa". NatureServe Explorer. Arlington, Virginia. Retrieved 20 September 2025.
  2. ^ a b c "Oenothera villosa Thunb". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 19 September 2025.
  3. ^ a b c d "Oenothera villosa subsp. strigosa (Rydb.) W.Dietr. & P.H.Raven". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 20 September 2025.
  4. ^ a b c d "Oenothera villosa subsp. villosa". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 20 September 2025.
  5. ^ a b Marcus, Joseph A. (20 April 2023). "Oenothera villosa". Plant Database. Lady Bird Johnson Wildflower Center. Retrieved 4 December 2023.
  6. ^ Dietrich, Rydberg; Raven, P.H (1977). Missouri Botany and Gardening Vol. 63.
  7. ^ Stevens, Orin (1963). Handbook of North Dakota Plants.
  8. ^ Freeman, Craig; Schofield, Eileen (1991). Roadside Wildflowers of the Southern Great Plains.
  9. ^ Heywood; et al. (2007). Flowering Plant Families of the Word.
  10. ^ Sohrabi, Nahid (2024). "The efficacy of evening primrose seed oil supplements on ART outcomes: A triple-blinded randomized placebo-controlled clinical trial". Advances in Integrative Medicine.