Pteridium aquilinum | |
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Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Division: | Polypodiophyta |
Class: | Polypodiopsida |
Order: | Polypodiales |
Family: | Dennstaedtiaceae |
Genus: | Pteridium |
Species: | P. aquilinum |
Binomial name | |
Pteridium aquilinum | |
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.
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]
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]
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]
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.
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]
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]
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]
P. aquilinum has been investigated for its anti-inflammatory and antioxidative properties. [27]
In Finnish traditional medicine bracken has been used as a remedy in many ways: [28]
The ferns are a group of vascular plants that reproduce via spores and have neither seeds nor flowers. They differ from mosses by being vascular, i.e., having specialized tissues that conduct water and nutrients, and in having life cycles in which the branched sporophyte is the dominant phase.
Bracken (Pteridium) is a genus of large, coarse ferns in the family Dennstaedtiaceae. Ferns (Pteridophyta) are vascular plants that have alternating generations, large plants that produce spores and small plants that produce sex cells. Brackens are noted for their large, highly divided leaves. They are found on all continents except Antarctica and in all environments except deserts, though their typical habitat is moorland. The genus probably has the widest distribution of any fern in the world.
Haumia-tiketike is the god of all uncultivated vegetative food in Māori mythology. He is particularly associated with the starchy rhizome of the Pteridium esculentum, which became a major element of the Māori diet in former times. He contrasts with Rongo, the god of kūmara and all cultivated food plants.
Fiddleheads or fiddlehead greens are the furled fronds from a fledgling fern, harvested for use as a vegetable.
Matteuccia is a genus of ferns with one species: Matteuccia struthiopteris. The species epithet struthiopteris comes from Ancient Greek words στρουθίων (strouthíōn) "ostrich" and πτερίς (pterís) "fern".
Petasites is a genus of flowering plants in the sunflower family, Asteraceae, that are commonly referred to as butterburs and coltsfoots. They are perennial plants with thick, creeping underground rhizomes and large rhubarb-like leaves during the growing season. Most species are native to Asia or southern Europe.
The order Cyatheales, which includes most tree ferns, is a taxonomic order of the fern class, Polypodiopsida. No clear morphological features characterize all of the Cyatheales, but DNA sequence data indicate the order is monophyletic. Some species in the Cyatheales have tree-like growth forms from a vertical rhizome, others have shorter or horizontal expanding rhizomes.
Onoclea sensibilis, the sensitive fern, also known as the bead fern, is a coarse-textured, medium to large-sized deciduous perennial fern. The name comes from its sensitivity to frost, the fronds dying quickly when first touched by it. It is sometimes treated as the only species in Onoclea, but some authors do not consider the genus monotypic.
Dennstaedtiaceae is one of fifteen families in the order Polypodiales, the most derived families within monilophytes (ferns). It comprises 10 genera with ca 240 known species, including one of the world's most abundant ferns, Pteridium aquilinum (bracken). Members of the order generally have large, highly divided leaves and have either small, round intramarginal sori with cup-shaped indusia or linear marginal sori with a false indusium formed from the reflexed leaf margin. The morphological diversity among members of the order has confused past taxonomy, but recent molecular studies have supported the monophyly of the order and the family. The reclassification of Dennstaedtiaceae and the rest of the monilophytes was published in 2006, so most of the available literature is not updated.
Bovine papillomaviruses (BPV) are a paraphyletic group of DNA viruses of the subfamily Firstpapillomavirinae of Papillomaviridae that are common in cattle. All BPVs have a circular double-stranded DNA genome. Infection causes warts of the skin and alimentary tract, and more rarely cancers of the alimentary tract and urinary bladder. They are also thought to cause the skin tumour equine sarcoid in horses and donkeys.
Osmundastrum is genus of leptosporangiate ferns in the family Osmundaceae with one living species, Osmundastrum cinnamomeum, the cinnamon fern. It is native to the Americas and eastern Asia, growing in swamps, bogs and moist woodlands.
Phlebodium aureum is an epiphytic fern native to tropical and subtropical regions of the Americas.
Hypolepis ambigua, commonly known as pigfern, is a species of fern that grows in New Zealand.
Ptaquiloside is a norsesquiterpene glucoside produced by bracken ferns during metabolism. It is identified to be the main carcinogen of the ferns and to be responsible for their biological effects, such as haemorrhagic disease and bright blindness in livestock and oesophageal, gastric cancer in humans. Ptaquiloside has an unstable chemical structure and acts as a DNA alkylating agent under physiological conditions. It was first isolated and characterized by Yamada and co-workers in 1983.
Pteridium esculentum, commonly known as bracken fern, Austral bracken or simply bracken, is a species of the bracken genus native to a number of countries in the Southern Hemisphere. Esculentum means edible. First described as Pteris esculenta by German botanist Georg Forster in 1786, it gained its current binomial name in 1908. The Eora people of the Sydney region knew it as gurgi.
Calochlaena dubia, commonly known as soft bracken, false bracken, common ground fern or rainbow fern, is a small Australian fern in the treefern family Dicksoniaceae. It is very common within its range, and often seen growing under eucalyptus forest, often on the poorer quality soils. It is an easy plant to grow in the garden.
Musotima nitidalis, also known as the golden brown fern moth, is a species of moth of the family Crambidae. This species was described by Francis Walker in 1866. It is native to Australia and New Zealand and was first found in Europe in 2009.
Myriopteris rawsonii, formerly known as Cheilanthes rawsonii, is a perennial fern native to Namaqualand in Southern Africa. Like many other cheilanthoid ferns, it is adapted to dry conditions, bearing a thick layer of pale hairs on the underside of its pinnate-pinnatifid leaves. It is the only African representative of its clade of cheilanthoids, the otherwise American genus Myriopteris. It spends much of the year in a dried-out, dormant state, rehydrating and putting out new growth during winter rains. Its name honors the botanist and civil servant Sir Rawson W. Rawson.
Pteridium aquilinum var. pubescens, the hairy brackenfern, is a fern native ranging from Alaska to Mexico.