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Pteridium aquilinum

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Pteridium aquilinum, commonly called bracken, brake, pasture brake, common bracken, and also known as eagle fern, is a species of fern occurring in temperate and subtropical regions in both hemispheres. Originally native to Eurasia and North America, the extreme lightness of its spores has led to it achieving a cosmopolitan distribution.

Pteridium aquilinum

Secure  (NatureServe)[1]
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Division: Polypodiophyta
Class: Polypodiopsida
Order: Polypodiales
Family: Dennstaedtiaceae
Genus: Pteridium
Species:
P. aquilinum
Binomial name
Pteridium aquilinum

Description

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Common bracken is a herbaceous perennial plant, deciduous in winter. The large, roughly triangular fronds are produced singly, arising upwards from an underground rhizome, and grow to 0.3–1 metre (1–3+1⁄2 feet) tall; the main stem, or stipe, is up to 1 centimetre (1⁄2 inch) in diameter at the base. It dies back to ground level in autumn.[2] The rhizome grows up to 3.5 metres (11+1⁄2 ft) deep, about 5 cm (2 in) in diameter, and up to 15 m (50 ft) long. Because it regrows in the spring from an underground rhizome, P. aquilinum tends to be found in dense colonies of genetically identical fronds. In the spring as the plant enters its growing cycle, fiddleheads are first sent up from the rhizome. The density and area covered by a single rhizome maximizes that rhizome's chance of biological success when sending up new growth. The new growth presents as vertical stalks, coiled and covered in silver-gray hairs, that can be several feet in height before unfurling into fronds.[3]

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    Amphicribral vascular bundle of a common bracken rhizome
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    Diagram of the plant's leaves
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    Leaves of a P. aquilinum plant

Reproduction

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Sporangia are formed in sori on the underside of the frond.[4] They are arranged in narrow brown bands, and form spores over July, August and September.[5]

Taxonomy

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It was traditionally treated as the sole species in the genus Pteridium (brackens); however, authorities have split and recognised up to 11 species in the genus. It was placed in the genus Pteridium by Friedrich Adalbert Maximilian Kuhn in 1879.[6] Genetic analysis of Pteridium from 100 different locations worldwide has revealed two distinct species and despite the common name "bracken" being shared, the "southern" species is Pteridium esculentum. Though the southern P. esculentum shows little genetic diversity among physically isolated locations, P. aquilinum has distinct groups at the continental scale. However, evidence of long-distance gene flow was found in samples taken from Hawaii that presented elements of both North American and Asian subspecies of P. aquilinum.[7]

Etymology

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Common bracken was first described as Pteris aquilina by Carl Linnaeus, in Volume 2 of his Species Plantarum in 1753. The origin of the specific epithet derived from the Latin aquila "eagle". In the reprint of the Flora Suecica in 1755, Linnaeus explains that the name refers to the image of an eagle seen in the transverse section of the root.[8] In spite of this, the opinion has been forwarded that the name pertains to the shape of the mature fronds appearing akin to an eagle's wing.[9] However, medieval scholars, including Erasmus, thought the pattern of the fibres seen in a transverse section of the stipe resembled a double-headed eagle or oak tree.

Distribution and habitat

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Bracken is native to Europe, Eastern Asia and North America,[5] but now has an almost cosmopolitan distribution.[10] In the Americas, it is found throughout the continental United States and the Canadian provinces of Ontario, Quebec, and Newfoundland. Its range's northern border extends to southern Alaska, while its southern reaches the northern portions of Mexico, as well as the Greater Antilles in the Caribbean.[5] Weedy in acidic upland pastures of northwestern Europe.[10]

Bracken grows in pastures, deciduous and coniferous woodlands, and hillsides. It prefers acidic soils.[5]

An adaptable plant, bracken readily colonises disturbed areas. It can even be aggressive in countries where it is native, such as England, where it has invaded heather (Calluna vulgaris (L.) Hull) stands on the North Yorkshire moors.[11] In Ireland, bracken is found in open woodland and sandy pastures.[4]

Toxicity

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The plant contains the carcinogenic compound ptaquiloside.[12] Ptaquiloside is known to cause hemorrhagic diseases in ruminants, tumors and hematological problems in non-ruminants, and is correlated with esophageal and gastric cancer in humans.[13][14] Chronic bracken consumption is also associated with upper digestive tract (UDT) squamous cell carcinomas in cattle (ruminants)—with the most aggressive and serious tumors located in the caudal (lower) UDT.[15]

High stomach cancer rates are found in Japan and North Wales, where the young stems are used as a vegetable, but it is unknown whether bracken plays any part or if the cancer can be attributed to another cause.[16] Consumption of ptaquiloside-contaminated milk is thought to contribute to human gastric cancer in the Andean states of Venezuela.[17] The spores have also been implicated as carcinogens. Consumption of contaminated water and meat may be dangerous as well.[18]

However, ptaquiloside is water-soluble, and is reduced by soaking bracken in cool water.[19] Korean and Japanese cooks have traditionally soaked the shoots in water and ash to detoxify the plant before eating.[20] Ptaquiloside also degenerates at room temperature, which explains why the rat studies were done with the toxin stored at −20 °C (−4 °F).[19] At boiling temperature, the carcinogen denatures almost completely.[19] Salt and baking soda also help with volatilizing the chemical.[19]

It has been suggested that selenium supplementation can prevent as well as reverse the immunotoxic effects induced by ptaquiloside from Pteridium aquilinum.[21]

Uses

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Food

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Commercially packaged warabimochi (bracken jelly) in Japan

Despite its established toxicity, P. aquilinum's global distribution—it is the fifth most widely distributed common weed species in the world—means that it has a long history of being consumed in many parts of the world.[13] The toxicity and wide distribution has led to variation in cultural attitudes towards the consumption of the plant. In the United Kingdom where P. aquilinum is extremely successful, the rhizome was once consumed during and after World War I.[22] However the Royal Horticultural Society now explicitly advises against its consumption due to toxicity.[23]

Bracken is a widely eaten vegetable in Korea, Japan, Russian Far East, and parts of China where they have historically been some of the most important wild vegetables consumed.[19] Populations of these countries where bracken is traditionally consumed have been able to access bracken in new locations after immigrating due to P. aquilinum's global ubiquity.

In Korea, bracken is known as gosari. It is soaked, parboiled, and stir-fried, and often eaten as a side dish (namul).[24] It is also a classic ingredient of bibimbap.[25]

In Japan, bracken is known as warabi (蕨, ワラビ), and a jelly-like starch made from it is a key ingredient for the chilled dessert warabimochi. As a type of sansai (mountain vegetables), young bracken shoots are steamed, boiled, or cooked in soups. The shoots are also preserved in salt, sake, or miso.[20]

Bracken shoots have been used to produce beer in Siberia, and among indigenous peoples of North America.[20]

The rhizome can be ground into flour to make bread. In the Canary Islands, the rhizome was historically used to make a porridge called gofio.[20]

Bracken leaves are used in the Mediterranean region to filter sheep's milk, and to store freshly made ricotta cheese.[20]

Young fronds of the bracken can be harvested easily and should be cooked for 30 to 60 minutes. Mature bracken is toxic due to thiaminase and can be destroyed by cooking. Should be avoided if not skilled enough to prepare it.[26]

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    Dried bracken (gosari) from Korea
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    Seasoned stir-fried bracken (gosari namul) from Korea

Pharmacology

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P. aquilinum has been investigated for its anti-inflammatory and antioxidative properties.[27]

Traditional medicine

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In Finnish traditional medicine bracken has been used as a remedy in many ways:[28]

  • Elias Lönnrot advised to use a powder made of the plant's roots to drive away maggots.
  • A decoction made of bracken was used to treat stomach problems, gout and joint pain.
  • The leaves have been used as filling in mattresses, because it was believed to lessen rheumatic pain and drive away vermins. These mattresses were also believed to block Earth radiation.

References

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  1. ^ "NatureServe Explorer 2.0 Pteridium aquilinum Bracken Fern". explorer.natureserve.org. Retrieved 5 October 2020.
  2. ^ Clapham, A.R., Tutin, T.G. and Warburg, E.F. 1968 Excursion Flora of the British Isles. Cambridge University Press. ISBN 0-521-04656-4.
  3. ^ "SCDNR - Species: Bracken Fern". www.dnr.sc.gov. Retrieved 2022-06-04.
  4. ^ a b Parnell, J. and Curtis, T. 2012. Webb's An Irish Flora. Cork University Press. ISBN 978-1-85918-478-3.
  5. ^ a b c d Common Weeds of the United States. New York: Dover. January 1971. p. 8. ISBN 0486205045.
  6. ^ Thomson, John A. (2004). "Towards a taxonomic revision of Pteridium (Dennstaedtiaceae)". Telopea. 10 (4): 793–803.
  7. ^ Wolf, Paul G.; Rowe, Carol A.; Kinosian, Sylvia P.; Der, Joshua P.; Lockhart, Peter J.; Shepherd, Lara D.; McLenachan, Patricia A.; Thomson, John A. (October 2019). "Worldwide relationships in the fern genus Pteridium (bracken) based on nuclear genome markers". American Journal of Botany. 106 (10): 1365–1376. doi:10.1002/ajb2.1365. ISSN 0002-9122. PMC 6856829. PMID 31545874.
  8. ^ radix oblique dissecta refert aliquatenus aquilam imperialem
  9. ^ Austin, Daniel F. (2004). Florida ethnobotany. CRC Press. p. 551. ISBN 978-0-8493-2332-4. Retrieved 30 June 2010.
  10. ^ a b Baker, Herbert G (1974). "The Evolution of Weeds". Annual Review of Ecology and Systematics. 5 (1). Annual Reviews: 1–24. doi:10.1146/annurev.es.05.110174.000245. ISSN 0066-4162.
  11. ^ Whitehead, S J; Digby, J (1997). "The morphology of bracken (Pteridium aquilinum (L.) Kuhn) in the North York Moors—a comparison of the mature stand and the interface with heather (Calluna vulgaris (L.) Hull) 1. The fronds". Annals of Applied Biology. 131: 103–116. doi:10.1111/j.1744-7348.1997.tb05399.x.
  12. ^ Gomes, Joana; Magalhães, Ana; Michel, Valérie; Amado, Inês F; Aranha, Paulo; Ovesen, Rikke G; Hansen, Hans C. B; Gärtner, Fátima; Reis, Celso A; Touati, Eliette (2012). "Pteridium aquilinum and Its Ptaquiloside Toxin Induce DNA Damage Response in Gastric Epithelial Cells, a Link with Gastric Carcinogenesis". Toxicological Sciences. 126 (1): 60–71. doi:10.1093/toxsci/kfr329. PMID 22143989.
  13. ^ a b Vetter, János (2009-03-03). "A biological hazard of our age: Bracken fern [ Pteridium aquilinum (L.) Kuhn] — A Review". Acta Veterinaria Hungarica. 57 (1): 183–196. doi:10.1556/avet.57.2009.1.18. ISSN 1588-2705. PMID 19457786.
  14. ^ Hirono, Iwao; Ito, Mitsuya; Yagyu, Shigeru; Haga, Masanobu; Wakamatsu, Kazumasa; Kishikawa, Teruaki; Nishikawa, Osamu; Yamada, Kiyoyuki; Ojika, Makoto; Kigoshi, Hideo (1993). "Reproduction of Progressive Retinal Degeneration (Bright Blindness) in Sheep by Administration of Ptaquiloside Contained in Bracken". Journal of Veterinary Medical Science. 55 (6): 979–983. doi:10.1292/jvms.55.979. PMID 8117827.
  15. ^ Masuda, E.K.; Kommers, G.D.; Martins, T.B.; Barros, C.S.L.; Piazer, J.V.M. (2011). "Morphological Factors as Indicators of Malignancy of Squamous Cell Carcinomas in Cattle Exposed Naturally to Bracken Fern (Pteridium aquilinum)". Journal of Comparative Pathology. 144 (1): 48–54. doi:10.1016/j.jcpa.2010.04.009. PMID 20542519.
  16. ^ I A Evans; B Widdop; R S Jones; G D Barber; H Leach; D L Jones & R Mainwaring-Burton (1971). "The possible human hazard of the naturally occurring bracken carcinogen". Biochem. J. 124 (2): 29P–30P. doi:10.1042/bj1240029pa. PMC 1177200. PMID 5158492.
  17. ^ Alonso-Amelot, Miguel E; Avendaño, Marisabel (2001). "Possible association between gastric cancer and bracken fern in Venezuela: An epidemiologic study". International Journal of Cancer. 91 (2): 252–259. doi:10.1002/1097-0215(200002)9999:9999<::AID-IJC1028>3.0.CO;2-H. PMID 11146454.
  18. ^ Tourchi-Roudsari, Motahhareh (2014). "Multiple effects of bracken fern under in vivo and in vitro conditions". Asian Pacific Journal of Cancer Prevention. 15 (18): 7505–7513. doi:10.7314/apjcp.2014.15.18.7505. ISSN 2476-762X. PMID 25292020.
  19. ^ a b c d e Shaw, Hank (30 June 2011). "The Bracken Fern: A Natural Born Killer?". The Atlantic. Retrieved 19 April 2017.
  20. ^ a b c d e Pieroni, Andrea (2005). Prance, Ghillean; Nesbitt, Mark (eds.). The Cultural History of Plants. Routledge. p. 35. ISBN 0415927463.
  21. ^ Latorre, A.O; Caniceiro, B.D; Wysocki, H.L; Haraguchi, M; Gardner, D.R; Górniak, S.L (2011). "Selenium reverses Pteridium aquilinum-induced immunotoxic effects". Food and Chemical Toxicology. 49 (2): 464–470. doi:10.1016/j.fct.2010.11.026. PMID 21112370.
  22. ^ Marrs, R. H.; Watt, A. S. (November 2006). "Biological Flora of the British Isles: Pteridium aquilinum (L.) Kuhn". Journal of Ecology. 94 (6): 1272–1321. Bibcode:2006JEcol..94.1272M. doi:10.1111/j.1365-2745.2006.01177.x. ISSN 0022-0477. S2CID 85114338.
  23. ^ "Bracken / RHS Gardening". www.rhs.org.uk. Retrieved 2022-06-04.
  24. ^ Mishan, Ligaya (16 February 2017). "At Cafe Lily, the Korean-Uzbek Menu Evokes a Past Exodus". The New York Times. Retrieved 19 April 2017.
  25. ^ Fontella, Amelia Cook (16 February 2017). "I brake for fernbrake". Isthmus. Retrieved 19 April 2017.
  26. ^ Hall, Alan (1973). The Wild Food Trailguide. Canada: Holt, Rinehart, Winston. p. 33. ISBN 0-03-007701-X.
  27. ^ Dion, C; Haug, C; Guan, H; Ripoll, C; Spiteller, P; Coussaert, A; Boulet, E; Schmidt, D; Wei, J; Zhou, Y; Lamottke, K (2015). "Evaluation of the anti-inflammatory and antioxidative potential of four fern species from China intended for use as food supplements". Natural Product Communications. 10 (4): 597–603. doi:10.1177/1934578X1501000416. PMID 25973486. S2CID 8419285.
  28. ^ Piirainen, Mikko; Piirainen, Pirkko; Vainio, Hannele (1999). Kotimaan luonnonkasvit [Native wild plants] (in Finnish). Porvoo, Finland: WSOY. p. 499. ISBN 951-0-23001-4.
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