Oenothera biennis

Oenothera biennis
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Rosids
Order:	Myrtales
Family:	Onagraceae
Genus:	Oenothera
Species:	O. biennis
Binomial name
Oenothera biennis L.
Synonyms [1]
Brunyera biennis (L.) Bubani Oenothera biennis var. vulgaris Torr. & A.Gray Onagra biennis (L.) Scop. Pseudo-oenothera virginiana Rupr.

Oenothera biennis, the common evening-primrose, ^[2] is a species of flowering plant in the family Onagraceae, native to eastern and central North America, from Newfoundland west to Alberta, southeast to Florida, and southwest to Texas, and widely naturalized elsewhere in temperate and subtropical regions. ^[3] Evening primrose oil is produced from the plant. ^[4]

Other common names include evening star, sundrop, weedy evening primrose, German rampion, hog weed, King's cure-all and fever-plant. ^{[4] [5]}

Description

Illustration of Oenothera biennis

Oenothera biennis usually has a life span of two years (biennial) growing to 1.6 m (5 ft 3 in) tall in the seeding year. ^[6] The leaves are lanceolate, 8–18 cm (3–7 in) long and 2–6 cm (3⁄4–2+1⁄4 in) wide, ^[6] produced in a tight rosette the first year, and spirally on a stem the second year. However, plants with annual life cycles are documented, and have been selected for under experimental conditions in environments with low competition. ^[7]

Growing cycle

Most commonly, O. biennis grows as a low, spreading herb in the first year, just a few centimetres tall, with its leaves spreading out in a rosette to cover the ground, whilst storing energy in a thick root. In the second year, it grows up much taller, to around 1.6 metres (5.2 ft) tall, on a semi-woody stem, which then flowers and seeds. This will usually die at first frosts, but occasionally grows another stem in the third year.

Blooming and fruiting

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 (1–2 in) diameter, with four bilobed petals. The flower structure has a bright nectar guide pattern, invisible to the naked eye. This pattern is apparent under ultraviolet light and visible to its pollinators, moths, butterflies, and bees.

The fruit is a capsule 2–4 cm (3⁄4–1+1⁄2 in) long and 4–6 mm (0.16–0.24 in) broad, containing numerous 1–2 mm (0.04–0.08 in) long seeds, released when the capsule splits into four sections at maturity. ^{[8] [9] [10] [11]}

Floral diagram.

Open flower in the evening

Closed flowers in the morning

Taxonomy

Oenothera biennis was given its scientific name in 1753 by Carl Linnaeus in the book Species Plantarum . It has no accepted subspecies or varieties, but it has 127 synonyms according to Plants of the World Online. ^[1]

Table of Synonyms

Name	Year	Rank	Notes
Brunyera biennis(L.) Bubani	1899	species	≡ hom.
Oenothera beckeriRenner	1942	species	= het., without a Latin descr.
Oenothera biennis var. albaAlef.	1866	variety	= het.
Oenothera biennis var. angustifoliaRenner	1956	variety	= het.
Oenothera biennis subsp. biennisThell.	1912	subspecies	= het., not validly publ.
Oenothera biennis subsp. caeciarumMunz	1965	subspecies	= het.
Oenothera biennis var. cantabrigianaB.M.Davis	1957	variety	= het.
Oenothera biennis subsp. centralisMunz	1965	subspecies	= het.
Oenothera biennis subsp. chicaginensis(de Vries ex Renner & Cleland) Á.Löve & D.Löve	1961	subspecies	= het.
Oenothera biennis subsp. grandifloraStomps	1948	subspecies	= het., nom. superfl.
Oenothera biennis subf. latifolia(Asch.) Thell.	1912	subform	= het.
Oenothera biennis f. leptomeres(Bartlett) P.D.Sell	2009	form	= het.
Oenothera biennis var. leptomeresBartlett	1914	variety	= het.
Oenothera biennis var. luteaAlef.	1866	variety	= het.
Oenothera biennis f. muricata(L.) H.Lév. ex Thell.	1912	form	= het.
Oenothera biennis var. muricata(L.) Torr. & A.Gray	1840	variety	= het.
Oenothera biennis f. nanellade Vries	1913	form	= het.
Oenothera biennis var. parvifloraAbrom.	1898	variety	= het., nom. illeg.
Oenothera biennis var. pycnocarpa(G.F.Atk. & Bartlett) Wiegand	1924	variety	= het.
Oenothera biennis subsp. rubricaulis(Kleb.) Stomps	1948	subspecies	= het., nom. illeg.
Oenothera biennis var. rubricaulis(Farw.) Farw.	1923	variety	= het.
Oenothera biennis subsp. suaveolens(Pers.) Rouy & E.G.Camus	1901	subspecies	= het.
Oenothera biennis var. sulphureade Vries ex Bartlett	1913	variety	= het.
Oenothera biennis var. vulgarisTorr. & A.Gray	1840	variety	≡ hom., not validly publ.
Oenothera brevicapsulaBartlett	1914	species	= het.
Oenothera brevispicataHudziok	1968	species	= het.
Oenothera cambricaRostański	1977	species	= het.
Oenothera cambrica var. impunctataRostański	1977	variety	= het.
Oenothera carinthiacaRostański	1977	species	= het.
Oenothera casimiriRostański	2004	species	= het.
Oenothera chicaginensisde Vries ex Renner & Cleland	1933	species	= het.
Oenothera chicaginensis var. bartlettiiSoldano	1992	variety	= het.
Oenothera chicaginensis var. minutifloraRostański & V.Jehlik	1979	variety	= het.
Oenothera chicaginensis var. parvifloraRenner	1956	variety	= het.
Oenothera chicagoensisRenner ex R.E.Cleland & Blakeslee	1930	species	= het.
Oenothera communisH.Lév.	1909	species	= het., nom. superfl.
Oenothera communis proles biennis(L.) H.Lév.	1910	proles	≡ hom.
Oenothera communis f. canescensH.Lév.	1909	form	= het.
Oenothera communis f. suaveolens(Pers.) H.Lév.	1909	form	= het.
Oenothera compactaHudziok	1968	species	= het.
Oenothera editicaulisHudziok	1968	species	= het.
Oenothera ersteinensisH.P.Linder & Jean	1970	species	= het.
Oenothera flaeminginaHudziok	1968	species	= het.
Oenothera furcaBoedijn	1924	species	= het.
Oenothera gauroidesHornem.	1813	species	= het.
Oenothera gauroides var. brevicapsula(Bartlett) R.R.Gates	1957	variety	= het.
Oenothera glabraMill.	1768	species	= het.
Oenothera grandiflora var. tracyi(Bartlett) R.R.Gates	1957	variety	= het.
Oenothera grandifoliaR.R.Gates	1936	species	= het.
Oenothera graveolensGilib.	1782	species	= het., opus utique oppr.
Oenothera hirtellade Vries	1903	species	= het., nom. illeg.
Oenothera inconspectaHudziok	1968	species	= het.
Oenothera indivisaHudziok	1968	species	= het.
Oenothera jueterbogensisHudziok	1968	species	= het.
Oenothera jueterbogensis var. macrospermaHudziok	1964	variety	= het.
Oenothera latipetala(Soldano) Soldano	2010	species	= het.
Oenothera macrosperma(Hudziok) Hudziok	1965	species	= het.
Oenothera marinellaeSoldano	1982	species	= het.
Oenothera mediaLink	1821	species	= het.
Oenothera mediomarchicaHudziok	1968	species	= het.
Oenothera muricataL.	1767	species	= het., nom. utique rej. prop.
Oenothera muricata var. latifoliaAsch.	1860	variety	= het.
Oenothera muricata var. rhodoneuraRenner	1937	variety	= het.
Oenothera muricata var. rubricaulisFarw.	1923	variety	= het.
Oenothera nissensisRostański	1965	species	= het.
Oenothera nissensis var. fiedleriGutte & Rostański	1981	variety	= het.
Oenothera novae-scotiae var. serratifoliaR.R.Gates	1936	variety	= het.
Oenothera nudaRenner ex Rostański	2009	species	= het.
Oenothera numismaticaBartlett	1914	species	= het.
Oenothera obscurifoliaHudziok	1968	species	= het.
Oenothera octolineataHudziok	1968	species	= het.
Oenothera paradoxaHudziok	1968	species	= het.
Oenothera paralamarckianaR.R.Gates	1936	species	= het.
Oenothera parviflora var. muricata(L.) Farw.	1923	variety	= het.
Oenothera pedemontanaSoldano	1983	species	= het.
Oenothera pellegriniiSoldano	1982	species	= het.
Oenothera pratincolaBartlett	1914	species	= het.
Oenothera pratincola var. numismatica(Bartlett) R.R.Gates	1957	variety	= het.
Oenothera pratincola f. typicaBartlett	1915	form	= het., not validly publ.
Oenothera pubescensNees	1841	species	= het., nom. illeg.
Oenothera punctulataRostański & Gutte	1971	species	= het.
Oenothera purpurataKleb.	1925	species	= het.
Oenothera pycnocarpaG.F.Atk. & Bartlett	1913	species	= het.
Oenothera pycnocarpa var. cleistogamaR.R.Gates	1936	variety	= het.
Oenothera pycnocarpa var. parvifloraR.R.Gates	1936	variety	= het.
Oenothera pyramidifloraHudziok	1968	species	= het.
Oenothera reynoldsiiBartlett	1914	species	= het.
Oenothera reynoldsii f. semialtaBartlett	1915	form	= het.
Oenothera reynoldsii f. typicaBartlett	1915	form	= het., not validly publ.
Oenothera rostanskiiV.Jehlík	1985	species	= het.
Oenothera royfraseriR.R.Gates	1936	species	= het.
Oenothera rubiellade Vries	1903	species	= het.
Oenothera rubiennisde Vries	1903	species	= het.
Oenothera rubricaulisKleb.	1913	species	= het.
Oenothera rubricaulis var. dentifoliaV.Jehlík & Rostański	1979	variety	= het.
Oenothera rubricaulis var. longistylisGutte & Rostański	1981	variety	= het.
Oenothera rubricauloidesRostański	2007	species	= het.
Oenothera ruderalisBartlett	1914	species	= het.
Oenothera sabulosaFarw.	1930	species	= het.
Oenothera sackvillensisR.R.Gates	1936	species	= het.
Oenothera sackvillensis var. albiviridisR.R.Gates	1936	variety	= het.
Oenothera sackvillensis var. royfraseri(R.R.Gates) R.R.Gates	1957	variety	= het.
Oenothera salicastrumde Vries	1913	species	= het.
Oenothera sesitensisSoldano	1978	species	= het.
Oenothera shullianaA.H.Sturtev.	1931	species	= het.
Oenothera stenomeresBartlett	1914	species	= het.
Oenothera stenomeres f. typicaBartlett	1915	form	= het., not validly publ.
Oenothera stucchiiSoldano	1978	species	= het.
Oenothera suaveolensPers.	1804	species	= het.
Oenothera suaveolens var. latipetalaSoldano	1981	variety	= het.
Oenothera tacikiiRostański	1965	species	= het.
Oenothera tracyiBartlett	1911	species	= het.
Oenothera turoviensisRostański	1965	species	= het.
Oenothera victoriniiR.R.Gates & Catches.	1933	species	= het.
Oenothera victorinii var. intermediaR.R.Gates	1936	variety	= het.
Oenothera victorinii var. parvifloraR.R.Gates	1936	variety	= het.
Oenothera victorinii f. rostanskii(V.Jehlík) V.Jehlík & Rostański	1995	form	= het.
Oenothera victorinii var. undulataR.R.Gates	1936	variety	= het.
Oenothera wratislaviensisRostański	2007	species	= het.
Onagra biennis(L.) Scop.	1771	species	≡ hom.
Onagra chrysantha var. latifoliaSpach	1835	variety	= het.
Onagra europaeaSpach	1835	species	= het.
Onagra media(Link) Spach	1835	species	= het.
Onagra muricata(L.) Moench	1794	species	= het.
Onagra vulgarisSpach	1835	species	= het.
Onosuris acuminataRaf.	1817	species	= het.
Pseudo-oenothera virginianaRupr.	1860	species	≡ hom., nom. superfl.
Notes: ≡ homotypic synonym  ; = heterotypic synonym

Ecology

This plant is a weedy species that favors disturbed environments. ^{[12] [13]} It has been introduced and become established on all continents except Antarctica. ^[14]

The seeds of the plant are important food for birds, ^[15] including American goldfinch, Northern bobwhite, and mourning dove, and it is a larval host for both the primrose moth and the white-lined sphinx moth. ^[16] Bumblebees and honeybees also visit the flowers. ^[12]

The primrose moth (Schinia florida) is a common consumer of Oenothera biennis. The adults lay eggs on the flower, and the emerging caterpillars feed on the plant.

Pink wing tips reveal Schinia florida in the flower of the evening primrose.

Primrose moth, Schinia florida, on an evening primrose, petals have been removed to reveal the insect.

The seeds of O. biennis can remain viable in the soil seed bank for 70 years or more. ^{[12] [14]}

Uses

Over the centuries, Indigenous people in North America have used the plant as food and traditional medicine. ^{[4] [17]}

The evening primrose was introduced to Europe in the early 17th century as an ornamental plant in botanical gardens where its flowers are favored for nectar by pollinators, such as bees, and its seeds are food for birds. ^{[4] [17]}

Food uses

Most of the plant parts are edible, having a taste that is mild. ^[17] The roots can be eaten raw or cooked like potatoes. ^[17] The leaves can be eaten raw in salads or cooked like spinach or in soups. ^[17] Anishinaabe tribes traditionally make tea from the evening primrose leaves for use as a dietary aid and to reduce fatigue. ^[17]

The flowering stems are preferably used when they are still young in June. They have to be peeled and can then be eaten raw or fried. The flower buds are regarded as a delicacy and can be harvested from June to October. ^[17]

The seeds have a protein content of about 15%, an oil content of 24%, and contain about 43% cellulose. ^[18] The proteins are especially rich in the sulphur-containing amino acids, methionine and cysteine, and tryptophan. ^{[18] [19]} Gamma-linolenic acid (GLA), and linoleic acid are present. ^{[17] [20] [21]} Mainly for these polyunsaturated fatty acids, evening primrose oil is sold as a dietary supplement. ^[17]

Research

See also: Gamma-Linolenic acid

There is not enough clinical evidence to support the use of evening primrose oil as a therapy for any medical condition. ^[4] A Cochrane review concluded that there was no effect of primrose oil on eczema. ^[22] The Mayo Clinic stated there was no good evidence that it affected eczema, diabetic neuropathy or premenstrual syndrome. ^[23]

The American Cancer Society stated that there was little evidence for its effectiveness as an anti-cancer agent, for which it is sometimes promoted, and "neither GLA nor other GLA-rich supplements (such as evening primrose oil) have been convincingly shown to be useful in preventing or treating any other health conditions." ^[24]

Adverse effects

Evening primrose oil is considered likely as safe in recommended doses. ^{[4] [23]} It may increase the risk of bleeding, a concern for patients with bleeding disorders or taking drugs that may increase bleeding. ^[4] The Mayo Clinic recommends caution in people with seizure disorders or mania, and by pregnant or breastfeeding women, and publishes a long list of possible side-effects. ^[23] Oral use of evening primrose oil may cause headaches or nausea. ^[23]

Traditional medicine

The whole plant and especially the leaves are traditionally boiled to tea by Anishinaabe tribes as an energy stimulant and to facilitate weight loss. ^[4] These tribes also use the roots externally as a poultice to treat piles and boils. ^[4] Additionally, they may be chewed and rubbed onto the muscles to improve strength. ^[17]

Agricultural practices

The knowledge of agricultural practices in the cultivation of evening primrose is relatively new and only pertain to the commercialized production of evening primrose seed oil. Information of agricultural practices for the production of root vegetable or other plant parts is not known yet.

The evening primrose prefers sunny and arid places with loamy soil and occurs below 700 metres (2,300 ft) above sea level. ^[17] One important prerequisite is to meet adequate nitrogen requirements. While too high nitrogen levels could lead to a quality and quantity decline of the oil content in the seeds, moderate nitrogen levels lead to increased seed quality and quantity. ^[20] Because the evening primrose is a light-dependent germinator, it is important that the seeds are not planted too deep into the soil, about 0.5–1.0 centimetre (0.2–0.4 in) deep. The cultivation of evening primrose is thus suitable for no-till farming, but the plants require an intense mechanical weed control. The seeds are tiny, about 0.3–0.7 grams (0.011–0.025 oz). They need approximately two to three weeks to germinate and are therefore very susceptible to the outgrowth of weeds.

Evening primrose seeds can be sown in the first half of April (spring seeds) or from mid-July to mid-August (autumn seeds). ^{[17] [20]} The time of harvest is approximately 75 to 80 days (spring seeds) or 100 days (autumn seeds) after flowering, and clearly influenced by the plant variety, climate conditions, soil fertility and sowing time. ^{[20] [21]} The population development and thus seed maturation of the evening primrose is very heterogeneous which is a rather difficult production factor. ^[17]

There is not much water needed during the vegetation period. ^[17] A study has shown, that the irrigation with salt water could increase the oil yield and quality in evening primrose seeds. This might be a great opportunity especially in regions with limited water resources. Thus, the evening primrose could be a valuable alternative oil crop in arid regions. ^[17]

Finally, the cultivation of evening primrose requires a proper field management otherwise the plant can become invasive. ^[17] If the seeds are used for pharmaceutical purposes it is also important to grow the evening primrose without any pesticides to avoid any chemical residues. ^[17]

• 
  Rosette
• 
  Flowers and fruit capsules
• 
  Primrose moth ( Schinia florida ) in flower
• 
  Habitat, dry and sunny

References

1. "Oenothera biennis L." Plants of the World Online . Royal Botanic Gardens, Kew . Retrieved 6 July 2025.
2. BSBI List 2007 (xls). Botanical Society of Britain and Ireland. Archived from the original (xls) on 2015-06-26. Retrieved 2014-10-17.
3. "Oenothera biennis". Germplasm Resources Information Network . Agricultural Research Service, United States Department of Agriculture . Retrieved 17 December 2017.
4. "Evening primrose oil". National Center for Complementary and Integrative Health, US National Institutes of Health. 1 August 2020. Retrieved 3 August 2022.
5. Blanchan, N. (1922). Wild Flowers Worth Knowing. Project Gutenberg Literary Archive Foundation.
6. Elias, Thomas S.; Dykeman, Peter A. (2009) [1982]. Edible Wild Plants: A North American Field Guide to Over 200 Natural Foods. New York: Sterling. p. 103. ISBN   978-1-4027-6715-9. OCLC   244766414.
7. Agrawal, Anurag A.; Johnson, Mark T.J.; Hastings, Amy P.; Maron, John L. (2013). "A Field Experiment Demonstrating Plant Life-History Evolution and Its Eco-Evolutionary Feedback to Seed Predator Populations". The American Naturalist. 181: S35-45. doi:10.1086/666727. hdl: 1813/66733 . PMID   23598358. S2CID   15852492.
8. Borealforest: Oenothera biennis Archived 2007-07-13 at the Wayback Machine
9. Plants of British Columbia: Oenothera biennis Archived 2016-12-21 at the Wayback Machine
10. Jepson Flora: Oenothera biennis Archived 2006-09-18 at the Wayback Machine
11. Ultraviolet Flowers: Oenothera biennis Archived 2006-11-14 at the Wayback Machine
12. "Common Evening Primrose (Oenothera biennis)". illinoiswildflowers.info.
13. "Oenothera biennis (Evening Primrose)". plants.ces.ncsu.edu. NC State Extension.
14. Steckel, Lawrence E.; Sosnoskie, Lynn M.; Steckel, Sandra J. (2019). "Common evening-primrose (Oenothera biennis L.)". Weed Technology. 33 (5): 757–760. doi: 10.1017/wet.2019.53 . S2CID   203879053.
15. "Oenothera biennis". Native Plant Database. Lady Bird Johnson Wildflower Center, University of Texas at Austin . Retrieved 7 December 2014.
16. The Xerces Society (2016), Gardening for Butterflies: How You Can Attract and Protect Beautiful, Beneficial Insects, Timber Press.
17. Immel, D.L. (21 June 2001). "Common evening primrose" (PDF). United States Department of Agriculture, National Plant Data Center.
18. Hudson, B. (1984). "Evening primrose (Oenothera spp.) oil and seed". Journal of the American Oil Chemists' Society. 61 (3): 540–543. doi:10.1007/bf02677026. S2CID   85005706.
19. Brosnan, J.T.; Brosnan, M.E. (2006). "The sulfur-containing amino acids: an overview". The Journal of Nutrition. 136 (6): 1636S –1640S. doi: 10.1093/jn/136.6.1636s . PMID   16702333.
20. Ghasemnezhad, A.; Honermeier, B. (2008). "Yield, oil constituents, and protein content of evening primrose (Oenothera biennis L.) seeds depending on harvest time, harvest method and nitrogen application". Industrial Crops and Products. 28 (1): 17–23. doi:10.1016/j.indcrop.2007.12.006.
21. Ghasemnezhad, A.; Honermeier, B. (2007). "Seed yield, oil content and fatty acid composition of Oenothera biennis L. affected by harvest date and harvest method". Industrial Crops and Products. 25 (3): 274–281. doi:10.1016/j.indcrop.2006.12.005.
22. Bamford, Joel (30 April 2013). "Oral evening primrose oil and borage oil for eczema". Cochrane Database of Systematic Reviews. 2013 (4): CD004416. doi:10.1002/14651858.CD004416.pub2. PMC   8105655 . PMID   23633319.
23. "Evening primrose (Oenothera spp.)". Mayo Clinic. 13 November 2020. Retrieved 3 August 2022.
24. "Gamma linolenic acid". American Cancer Society. 13 May 2010. Archived from the original on 6 August 2013. Retrieved 1 August 2013.

External links

• Profile: Yellow Evening-primrose (Oenothera biennis) Photos, Drawings, Text. (Wild Plants of Winnipeg from Nature Manitoba)