Pteridium aquilinum

Pteridium aquilinum, commonly calledbracken,brake,pasture brake, common bracken, and also known aseagle fern, is a species offernoccurring 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 acosmopolitan distribution.
Common bracken is aherbaceousperennialplant,deciduousin winter. The large, roughly triangularfrondsare produced singly, arising upwards from an undergroundrhizome, and grow to0.3–1 metre (1–3+1⁄2feet) tall; the main stem, or stipe, is up to1 centimetre (1⁄2inch) in diameter at the base. It dies back to ground level in autumn.The rhizome grows up to3.5 metres (11+1⁄2ft) 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. aquilinumtends to be found in dense colonies of genetically identical fronds. Such colonies can be as much as 650 years of age, with individual rhizomes living up to 72 years.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.
Sporangia are formed in sori on the underside of the frond.They are arranged in narrow brown bands, and form spores over July, August and September.
It was traditionally treated as the sole species in the genusPteridium(brackens); however, authorities have split and recognised up to 11 species in the genus. It was placed in the genusPteridiumbyFriedrich Adalbert Maximilian Kuhnin 1879.Genetic analysis ofPteridiumfrom 100 different locations worldwide has revealed two distinct species and despite the common name "bracken" being shared, the "southern" species isPteridium esculentum. Though the southernP. esculentumshows little genetic diversity among physically isolated locations,P. aquilinumhas 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 ofP. aquilinum.
Common bracken was first described asPteris aquilinabyCarl Linnaeus, in Volume 2 of hisSpecies Plantarumin 1753. The origin of thespecific epithetderived from theLatinaquila"eagle". In the reprint of theFlora Suecicain 1755, Linnaeus explains that the name refers to the image of an eagle seen in the transverse section of the root.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.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.
Bracken is native to Europe, Eastern Asia and North America,but now has an almostcosmopolitan distribution.In the Americas, it is found throughout the continentalUnited Statesand theCanadianprovinces ofOntario,Quebec, andNewfoundland. Its range's northern border extends to southernAlaska, while its southern reaches the northern portions ofMexico, as well as theGreater Antillesin theCaribbean.Weedyin acidicupland pasturesofnorthwestern Europe.
Bracken grows in pastures, deciduous and coniferous woodlands, and hillsides. It prefersacidicsoils.
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.InIreland, bracken is found in open woodland and sandy pastures.
The plant contains thecarcinogeniccompoundptaquiloside.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.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.
Highstomach cancerrates are found inJapanandNorth 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.Consumption of ptaquiloside-contaminated milk is thought to contribute to human gastric cancer in the Andean states ofVenezuela.Thesporeshave also been implicated as carcinogens. Consumption of contaminated water and meat may be dangerous as well.
However, ptaquiloside is water-soluble, and is reduced by soaking bracken in cool water.Korean and Japanese cooks have traditionally soaked the shoots in water andashto detoxify the plant before eating.Ptaquiloside also degenerates at room temperature, which explains why the rat studies were done with the toxin stored at −20 °C (−4 °F).At boiling temperature, the carcinogen denatures almost completely.Saltandbaking sodaalso help with volatilizing the chemical.
It has been suggested thatseleniumsupplementation can prevent as well as reverse the immunotoxic effects induced by ptaquiloside fromPteridium aquilinum.
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.The toxicity and wide distribution has led to variation in cultural attitudes towards the consumption of the plant. In the United Kingdom whereP. aquilinumis extremely successful, the rhizome was once consumed during and after World War I.However the Royal Horticultural Society now explicitly advises against its consumption due to toxicity.
Bracken is a widely eatenvegetablein Korea, Japan, Russian Far East, and parts of China where they have historically been some of the most important wild vegetables consumed.Populations of these countries where bracken is traditionally consumed have been able to access bracken in new locations after immigrating due toP. aquilinum's global ubiquity.
In Korea, bracken is known asgosari. It is soaked, parboiled, and stir-fried, and often eaten as a side dish (namul).It is also a classic ingredient ofbibimbap.
In Japan, bracken is known aswarabi(蕨, ワラビ), and a jelly-like starch made from it is a key ingredient for the chilled dessertwarabimochi.  As a type ofsansai(mountain vegetables), young bracken shoots are steamed, boiled, or cooked in soups. The shoots are also preserved in salt,sake, ormiso.
Bracken shoots have been used to produce beer inSiberia, and among indigenous peoples of North America.
Therhizomecan be ground into flour to make bread. In theCanary Islands, the rhizome was historically used to make aporridgecalledgofio.
Bracken leaves are used in theMediterraneanregion to filter sheep's milk, and to store freshly madericottacheese.
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.
P. aquilinumhas been investigated for its anti-inflammatory and antioxidative properties.
In Finnish traditional medicine bracken has been used as a remedy in many ways: