Editing Bracken

{{Short description|Genus of ferns}}
{{Redirect|Pteridium|the Ediacaran organism|Pteridinium}}
{{Other uses}}
{{Automatic taxobox
| image = Pteridium_aquilinum_nf.jpg
| image_caption = ''Pteridium aquilinum''<ref>painting circa 1920 by the Swedish botanist C. A. M. Lindman (1856–1928), taken from his book(s) Bilder ur Nordens Flora (first edition published 1901–1905, supplemented edition 1917–1926?).</ref>
| taxon = Pteridium
| authority = Gled. ex Scop. 1760 not Raf. 1814 ([[Pteridaceae]])
| subdivision_ranks = Species
| subdivision = See [[#Species|text]]
}}

'''Bracken''' ('''''Pteridium''''') is a [[genus]] of large, coarse [[fern]]s in the [[family (biology)|family]] [[Dennstaedtiaceae]]. Ferns (Pteridophyta) are [[vascular plant]]s that have [[alternation of generations]], large plants that produce spores and small plants that produce [[gamete|sex cells]] (eggs and sperm). 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.

The word ''bracken'' is of [[Old Norse]] origin, related to Swedish ''bräken'' and Danish ''bregne'', both meaning fern.
In the past, the genus was commonly treated as having only one species, ''[[Pteridium aquilinum]]'', but the recent trend is to subdivide it into about ten species.

Like other ferns, brackens do not have seeds or fruits, but the immature fronds, known as ''[[fiddlehead]]s'', are sometimes eaten, although some are thought to be carcinogenic.

==Description==
[[Image:Pteridium leaf kz1.jpg|thumb|Sori (paler green) along outer edge on underside of leaves]]

Bracken is one of the oldest ferns, with fossil records over [[Eocene|55 million years old]] having been found. The plant sends up large, triangular [[Frond|fronds]] from a wide-creeping underground [[rootstock]], and may form dense [[thicket|thickets]]. This rootstock may travel a meter or more underground between fronds. The fronds may grow up to {{convert|2.5|m|ft|abbr=on|frac=2}} long or longer with support, but typically are in the range of {{convert|0.6–2|m|ft|abbr=on|frac=2}} high. In cold environments, bracken is [[deciduous]] and, as it requires well-drained soil, is generally found growing on the sides of hills.

Fern [[spore]]s are contained in structures found on the underside of the leaf called [[Sorus|sori]]. The linear, leaf-edge pattern of these in bracken is different from that in most other ferns, where the sori are circular and occur towards the center of the leaf.

== Species ==
<ref>[http://www.theplantlist.org/tpl1.1/search?q=Pteridium The Plant List, search for ''Pteridium'']</ref>

{{Columns-list|colwidth=30em|
# ''[[Pteridium aquilinum]]'' - nearly cosmopolitan
# ''[[Pteridium arachnoideum]]'' - Mexico, Central and South America, [[Galápagos]]
# ''[[Pteridium caudatum]]'' - Mexico, Central and South America, Florida, West Indies
# ''[[Pteridium centrali-africanum]]'' - Zaire, Zambia, Tanzania, Burundi
# ''[[Pteridium esculentum]]'' - China, Southeast Asia, Australia, New Zealand
# ''[[Pteridium falcatum]]'' - [[Guangxi]]
# ''[[Pteridium feei]]'' - Mexico, Central America
# ''[[Pteridium lineare]]'' - [[Yunnan]]
# ''[[Pteridium revolutum]]'' - China
# ''[[Pteridium tauricum]]'' - [[Caucasus]]
# ''[[Pteridium yunnanense]]'' - [[Yunnan]]
}}

==Distribution and habitat==
''[[Pteridium aquilinum]]'' (bracken or common bracken) is the most common species with a [[cosmopolitan distribution]], occurring in [[temperate]] and [[subtropical]] regions throughout much of the world. It is a prolific and abundant plant in the moorlands of Ireland, where it is limited to altitudes of below 600 metres. It does not like poorly drained marshes or fen. It has been observed growing in soils from [[pH]] 2.8 to 8.6. Exposure to cold or high pH inhibits its growth. It causes such a problem in invading pasturelands that at one time the British government had an eradication programme. Special filters have even been used on some British water supplies to filter out the bracken spores.<ref>{{cite web|url=https://www.independent.co.uk/arts-entertainment/spores-for-thought-1364558.html|title=SPORES FOR THOUGHT|date=22 September 1996|website=independent.co.uk|access-date=6 April 2018}}</ref><ref>[https://species.nbnatlas.org/species/NBNSYS0000002031 NBN distribution map for the United Kingdom]</ref>

Bracken is a characteristic moorland plant in Ireland which over the last decades has increasingly out-competed characteristic ground-cover plants such as [[moor grass]]es, [[cowberry]], [[bilberry]], and [[Ericaceae|heathers]], and now covers a considerable part of upland moorland.
Once valued and gathered for use in animal bedding, tanning, soap and glass making, and as a fertiliser, bracken is now seen as a pernicious, invasive, and opportunistic plant, taking over from the plants traditionally associated with open moorland and reducing easy access by humans. It is toxic to cattle, dogs, sheep, pigs, and horses, and is also linked to cancers in humans.<ref>{{cite journal|last1=Potter|first1=D.M.|title=Carcinogenic effects of ptaquiloside in bracken fern and related compounds|journal=British Journal of Cancer|date=4 September 2000|volume=83|issue=7|pages=914–920|doi=10.1054/bjoc.2000.1368|pmid=10970694|pmc=2374682}}</ref> It can harbour high levels of sheep ticks, which can pass on [[Lyme disease]]. Grazing provided some control by stock trampling, but this has almost ceased since the [[2001 United Kingdom foot-and-mouth outbreak|2001 foot-and-mouth disease outbreak]] reduced commercial livestock production. Global climatic changes have also suited bracken well and contributed to its rapid increase in land coverage.

Bracken is a well-adapted pioneer plant which can colonise land quickly, with the potential to extend its area by as much as 1%–3% per year. This ability to expand rapidly at the expense of other plants and wildlife can cause major problems for land users and managers. It colonises ground with an open vegetation structure, but is slow to colonise healthy, well managed heather stands.

Bracken presents a threat to biodiversity. Many plant species occur only on upland moorland, tied to unique features in the habitat. The loss and degradation of such areas due to the dominance of bracken has caused many species to become rare and isolated.{{Citation needed|date=April 2014}}

==Ecology==
Evolutionarily, bracken may be considered one of the most successful ferns. It is considered highly [[invasive plants|invasive]], and can survive in [[acid soils]].<ref>{{cite book |title=Bracken and Its Management |date=2003 |publisher=Sports Turf Research Institute |location=Bingley, England}}</ref>

=== Fungal associations ===
Woodland [[fungi]] such as ''[[Mycena epipterygia]]'' can be found growing under the bracken canopy. Both ''[[Camarographium stephensii]]'' and ''[[Typhula quisquiliaris]]'' grow primarily from dead bracken stems.

=== Other plant associations ===
[[File:Curled bracken fronds.JPG|thumb|Young bracken fronds curled]]

Bracken is known to produce and release [[allelopathic]] chemicals, which is an important factor in its ability to dominate other vegetation, particularly in regrowth after fire. Its chemical emissions, shady canopy, and thick litter inhibit other plant species from establishing themselves – with the occasional exception of plants which support rare butterflies. Herb and tree seedling growth may be inhibited even after bracken is removed, apparently because active plant toxins remain in the soil.

Bracken substitutes the characteristics of a woodland [[Canopy (forest)|canopy]], and is important for giving shade to European plants such as [[common bluebell]] and [[Anemone nemorosa|wood anemone]] where the woodland does not exist. These plants are intolerant to stock trampling. Dead bracken provides a warm microclimate for development of the immature stages. [[Climbing corydalis]], [[Gladiolus|wild gladiolus]], and [[chickweed wintergreen]] also seem to benefit from the conditions found under bracken stands.

The high humidity in the stands helps mosses survive underneath, including ''Campylopus flexuosus'', ''[[Hypnum cupressiforme]]'', ''[[Polytrichum commune]]'', ''Pseudoscelopodium purum'' and ''Rhytidiadelphus squarrosus''.

==Uses==
[[File:Dried Eastern brakenfern.jpg|thumb|Dried bracken bundles (''P.&nbsp;aquilinum'') at a food market in South Korea]]

=== Food ===
[[File:Senjuan_Yoshimune_warabimochi.jpg|thumb|''[[Warabimochi]]'' bracken jelly, a traditional [[Japan]]ese dessert.  The darker jelly on the left is made from pure bracken powder, while the lighter jelly on the right uses other starches as well.]]

Bracken [[fiddlehead]]s have been eaten by many cultures throughout history, either fresh, cooked, or pickled. ''Pteridium aquilinum'' is especially common in [[East Asia]]n cuisine.

In Korea, bracken (sometimes referred to as 'fernbrake' in Korean recipes) is known as ''gosari'' (고사리), and is a typical ingredient in ''[[bibimbap]]'', a popular mixed rice dish.<ref>{{Cite news|url=http://isthmus.com/food-drink/reviews/five-star-korean-bbq/|title=I brake for fernbrake|last=Fontella|first=Amelia Cook|date=16 February 2017|work=[[Isthmus (newspaper)|Isthmus]]|access-date=19 April 2017}}</ref> Stir-fried bracken (''gosari [[namul]]'') is also a common side dish (''[[banchan]]'') in Korea.<ref>{{Cite news|url=https://www.nytimes.com/2017/02/16/dining/cafe-lily-review-bensonhurst-korean-uzbek.html|title=At Cafe Lily, the Korean-Uzbek Menu Evokes a Past Exodus|last=Mishan|first=Ligaya|date=16 February 2017|work=[[The New York Times]]|access-date=19 April 2017}}</ref>

In Japan, bracken is known as ''warabi'' (わらび), and is steamed, boiled, or cooked in soups. ''[[Warabimochi]]'' bracken jelly, named after its resemblance to ''[[mochi]]'' rice cakes, is a popular traditional dessert, although commercial variants are often made with cheaper [[potato starch]] instead.  The fiddleheads are also preserved in salt, [[sake]], or [[miso]].<ref name="pieroni">{{cite book |editor1-last=Prance |editor1-first=Ghillean |editor2-last=Nesbitt |editor2-first=Mark |last1=Pieroni |first1=Andrea |author-link=Andrea Pieroni |date=2005 |title=The Cultural History of Plants |publisher=Routledge |page=35 |isbn=0415927463}}</ref>

In China, bracken is known as ''juecai'' (蕨菜), and is eaten like vegetables or preserved by drying. Also called "fernbrake", it is used as a vegetable in soups and stews.<ref>Longmeimei cooking channel: Archived at [https://ghostarchive.org/varchive/youtube/20211211/Oy3ixwCSgZk Ghostarchive]{{cbignore}} and the [https://web.archive.org/web/20210319155122/https://www.youtube.com/watch?v=Oy3ixwCSgZk Wayback Machine]{{cbignore}}: {{Citation|title=Authentic Guizhou Special Sauerkraut with Wild Herbs and Green Vegetables| date=13 March 2021 |url=https://www.youtube.com/watch?v=Oy3ixwCSgZk|language=en|access-date=2021-06-26}}{{cbignore}}</ref>

Bracken [[rhizome]]s can be ground into flour to make bread. In the [[Canary Islands]], the rhizome was historically used to make a porridge called ''gofio''.<ref name="pieroni"/> Both fronds and rhizomes have been used to produce beer in Siberia, and among indigenous peoples of North America.<ref name="pieroni"/><ref>{{cite book|last1=Jones|first1=David L.|title=Encyclopaedia of ferns : an introduction to ferns, their structure, biology, economic importance, cultivation and propagation|date=1987|publisher=Timber Press|location=Portland, Ore.|isbn=978-0881920543|page=[https://archive.org/details/encyclopaediaoff00jone/page/13 13]|url-access=registration|url=https://archive.org/details/encyclopaediaoff00jone/page/13}}</ref>

Bracken leaves are used in the Mediterranean region to filter sheep's milk, and to store freshly made [[ricotta]] cheese.<ref name="pieroni"/>

''P. esculentum'' rhizomes were traditionally used by the [[Māori people]] of New Zealand as a staple food, and are known as ''aruhe''. They were eaten by exploring or hunting groups away from permanent settlements. The plant was widely distributed across New Zealand as a result of prehistoric deforestation, and planting on rich soils, which produced the best rhizomes. The rhizomes were dried, and could be heated and softened with a pounder (''patu aruhe''),<ref name=":0">{{Cite book |last1=Lehnebach |first1=Carlos A. |url=https://www.wikidata.org/wiki/Q124332398 |title=Flora: Celebrating our Botanical World |last2=Regnault |first2=Claire |last3=Rice |first3=Rebecca |last4=Awa |first4=Isaac Te |last5=Yates |first5=Rachel A. |date=2023-11-01 |publisher=Te Papa Press |isbn=978-1-9911509-1-2 |pages=310 |language=English}}</ref> after which the starch could be sucked from the fibers. ''Patu aruhe'' were important ritual items, and several distinct styles were developed.<ref>{{cite journal |author1=McGlone, Matt S. |author2=Wilmshurst, Janet M. |author3=Leach, Helen M. |year=2005 |title=An ecological and historical review of bracken (''Pteridium esculentum'') in New Zealand, and its cultural significance |url=https://newzealandecology.org/nzje/2269 |journal=[[New Zealand Journal of Ecology]] |volume=28 |pages=165–184}}</ref><ref name=":0" />

=== Source of potash ===
Green bracken ferns average 25% [[potash]] and can contain as much as 55%.<ref>{{cite book |last=Kourik |first=Robert |year=1986 |title=Designing and maintaining your edible landscape naturally |others=Kane, Mark |location=Santa Rosa, CA |publisher=Metamorphic Press |isbn=0-9615848-0-7 |page=268 |oclc=14258849 |url=https://www.worldcat.org/oclc/14258849}}</ref> It has advantages over other sources of plant ash, such as hardwood, due to its high potash yield as a percentage of both dry and fresh mass, abundance, growth rate, and ease of harvesting.<ref name=rymer1976>{{cite journal |last=Rymer |first=Julia |date=July 1976 |title=The history and ethnobotany of bracken |journal=Botanical Journal of the Linnean Society |volume=73 |issue=1–3 |pages=151–176 |doi=10.1111/j.1095-8339.1976.tb02020.x}}</ref> Bracken has been recognized as a source of potash since at least the 10th&nbsp;century AD, with numerous references in European texts, typically in relation to its use for soap and glass making.<ref name=rymer1976/> The turn to mined sources of potash in the industrial age ended significant use of bracken as a source of potash, contributing to its status as a troublesome weed.<ref name=rymer1976/>

=== Others ===
Bracken has traditionally been used for animal bedding, which later breaks down into a rich [[mulch]] that could be used as fertilizer. It is still used this way in [[Wales]].<ref name="abdn.ac.uk">{{cite web |url=http://www.abdn.ac.uk/organic/organic_24.php |title=Uses for Bracken |access-date=2009-07-08 |url-status=dead |archive-url=https://web.archive.org/web/20091212233858/http://www.abdn.ac.uk/organic/organic_24.php |archive-date=2009-12-12 }}</ref> It is also used as a winter mulch, which has been shown to reduce the loss of [[potassium]] and [[nitrogen]] in the soil, and to lower [[soil pH]].<ref name="abdn.ac.uk"/>

==Toxicity==
Bracken contains the [[carcinogen]]ic compound [[ptaquiloside]], which causes damage to DNA, thus leading to cancers of the digestive tract.<ref>{{cite journal |doi=10.1093/toxsci/kfr329 |pmid=22143989 |title=Pteridium aquilinum and Its Ptaquiloside Toxin Induce DNA Damage Response in Gastric Epithelial Cells, a Link with Gastric Carcinogenesis |journal=Toxicological Sciences |volume=126 |issue=1 |pages=60–71 |year=2012 |last1=Gomes |first1=Joana |last2=Magalhães |first2=Ana |last3=Michel |first3=Valérie |last4=Amado |first4=Inês F |last5=Aranha |first5=Paulo |last6=Ovesen |first6=Rikke G |last7=Hansen |first7=Hans C B |last8=Gärtner |first8=Fátima |last9=Reis |first9=Celso A |last10=Touati |first10=Eliette |doi-access=free }}</ref> High [[stomach cancer]] rates are found in [[Japan]] and [[North Wales]], where bracken is often eaten, but it is unclear whether bracken plays a role.<ref>{{cite journal|author1=I A Evans |author2=B Widdop |author3=R S Jones |author4=G D Barber |author5=H Leach |author6=D L Jones |author7=R Mainwaring-Burton |name-list-style=amp | title=The possible human hazard of the naturally occurring bracken carcinogen|journal=Biochem. J.|year=1971|volume= 124 |issue=2 |pages=29P–30P|pmid=5158492|pmc=1177200 |doi=10.1042/bj1240029pa}}</ref> Consumption of ptaquiloside-contaminated milk is thought to contribute to human gastric cancer in the Andean states of [[Venezuela]].<ref>{{cite journal |doi=10.1002/1097-0215(200002)9999:9999<::AID-IJC1028>3.0.CO;2-H |title=Possible association between gastric cancer and bracken fern in Venezuela: An epidemiologic study |journal=International Journal of Cancer |volume=91 |issue=2 |pages=252–259 |year=2001 |last1=Alonso-Amelot |first1=Miguel E |last2=Avendaño |first2=Marisabel |pmid=11146454 |doi-access=free }}</ref> The [[spore]]s have also been implicated as carcinogens.

However, ptaquiloside is water-soluble and destroyed in heat (by cooking) and alkaline conditions (by soaking).<ref>{{cite web|url=http://www.fs.fed.us/database/feis/plants/fern/pteaqu/all.html|title=Pteridium aquilinum|website=www.fs.fed.us|access-date=6 April 2018}}</ref> Korean and Japanese cooks have traditionally soaked the shoots in water and [[ash]] to detoxify the plant before eating.<ref name="pieroni"/> Ptaquiloside also degenerates at room temperature, and denatures almost completely at boiling temperature.<ref name="atlantic">{{cite web|url=https://www.theatlantic.com/health/archive/2011/06/the-bracken-fern-a-natural-born-killer/241271/|title=The Bracken Fern: A Natural Born Killer?|first=Hank|last=Shaw|date=2011-06-30|website=theatlantic.com|access-date=6 April 2018}}</ref> Despite this, moderation of consumption is still recommended to reduce chances of cancer formation.<ref name="atlantic"/> The British Royal Horticultural Society recommends against consumption of bracken altogether, by both humans and livestock.<ref>{{cite web|title=Dol Sot Bibimbap|url=http://apps.rhs.org.uk/advicesearch/Profile.aspx?pid=445|access-date=2011-12-19|archive-url=https://web.archive.org/web/20111111190952/http://apps.rhs.org.uk/advicesearch/profile.aspx?PID=445|archive-date=2011-11-11|url-status=dead}}</ref>

Ptaquiloside has been shown to leach from wild bracken plants into the water supply, which has been implicated in high rates of stomach and oesophageal cancers in areas with high bracken growth, such as Wales and South America.<ref name="rasmussen">{{cite web|url=https://www.theguardian.com/society/2004/sep/09/research.science|title=The fatal fern|first=Kate|last=Ravilious|date=9 September 2004|website=the Guardian|access-date=6 April 2018}}</ref>

Uncooked bracken also contains the [[enzyme]] [[thiaminase]], which breaks down [[thiamine]] (vitamin B1). Excessive consumption of bracken can lead to vitamin B1 deficiency ([[beriberi]]), especially in animals with simple stomachs. [[Ruminant]]s are less vulnerable because they synthesize thiamine.<ref>{{Cite journal |last1=Pan |first1=Xiaohua |last2=Nan |first2=Xuemei |last3=Yang |first3=Liang |last4=Jiang |first4=Linshu |last5=Xiong |first5=Benhai |date=September 2018 |title=Thiamine status, metabolism and application in dairy cows: a review |journal=British Journal of Nutrition |language=en |volume=120 |issue=5 |pages=491–499 |doi=10.1017/S0007114518001666 |issn=0007-1145|doi-access=free |pmid=29986774 }}</ref>

=== In animals ===
Ptaquiloside from bracken has been shown to be [[carcinogen]]ic in some animals.<ref name=Evans71>{{cite journal |vauthors=Evans IA, Widdop B, Jones RS |title=The possible human hazard of the naturally occurring bracken carcinogen |journal=Biochem. J. |volume=124 |issue=2 |pages=29P–30P |date=September 1971 |pmid=5158492 |pmc=1177200 |display-authors=etal|doi=10.1042/bj1240029pa }}</ref> Animals may ingest the plant when other sources of food are unavailable, such as during droughts or after snowfalls.

In cattle, bracken poisoning can occur in acute and chronic forms, acute poisoning being the most common. Milk from cows that have eaten bracken may also contain ptaquiloside, which is especially concentrated in [[buttermilk]].<ref name="rasmussen"/> In pigs and horses, bracken poisoning induces vitamin B1 deficiency.<ref>{{cite book |author1=Auld, RA |author2=Medd, RW |title=Weeds |publisher=Inkata Press |location=Sydney |year=1992 }}</ref>

=== In insects ===
[[Hydrogen cyanide]] is released by the young fronds of bracken when eaten by mammals or insects.<ref>{{cite journal|last=Amelot ME|first=Alonso|date=February 2005|title=Kinetics of the natural evolution of hydrogen cyanide in plants in neotropical Pteridium arachnoideum and its ecological significance|journal=Journal of Chemical Ecology|volume=31 | issue = 2|pages=315–31|doi=10.1007/s10886-005-1343-z|pmid=15856786|bibcode=2005JCEco..31..315A |citeseerx=10.1.1.517.4271|s2cid=30063246}}</ref> Two major insect [[moulting]] hormones, alpha [[ecdysone]] and 20-hydroxyecdysone, are found in bracken. These cause uncontrollable, repeated moulting in insects ingesting the fronds, leading to rapid death.<ref>{{cite journal | title= Insect Hormones: Alpha Ecdysone and 20-Hydroxyecdysone in Bracken Fern|journal= Science|volume=157 |pages=1436–1438|date=22 September 1967 |doi= 10.1126/science.157.3795.1436 |pmid= 6037858 |issue=3795|last1= Kaplanis |first1= J. N. |last2= Thompson |first2= M. J. |last3= Robbins |first3= W. E. |last4= Bryce |first4= B. M. |bibcode= 1967Sci...157.1436K|s2cid= 37746757}}</ref> Bracken is currently under investigation as a possible source of new [[insecticide]]s.<ref>{{cite journal |vauthors=Jbilou R, Amri H, Bouayad N, Ghailani N, Ennabili A, Sayah F |title=Insecticidal effects of extracts of seven plant species on larval development, α-amylase activity and offspring production of ''Tribolium castaneum'' (Herbst) (Insecta: Coleoptera: Tenebrionidae) |journal=Bioresour. Technol. |volume=99 |issue=5 |pages=959–64 |date=March 2008 |pmid=17493805 |doi=10.1016/j.biortech.2007.03.017 |bibcode=2008BiTec..99..959J }}</ref>

==Archaeology==
[[File:Bleak hillside with bracken - geograph.org.uk - 1618991.jpg|thumb|200px|Bracken in Ireland with a linear pattern running across the hillside, a possible indication of past cultivation.]]
Many sites have archaeological remains dating from the [[Neolithic]] and [[Bronze Age]]s through to the [[Industrial Revolution]]. The root systems of established bracken stands degrade archaeological sites by disrupting the [[strata]] and other physical evidence. These rhizomes may travel a metre or more underground between fronds and form 90% of the plant, with only the remainder being visible.

==Control==
Some small level of scattered cover can provide beneficial habitats for some wildlife, at least in the UK (as given above). However, on balance, removing bracken encourages primary habitats to re-establish, which are of greater importance for wildlife. Control is a complex question with complex answers, which need to form part of a wider approach. Management can be difficult and expensive; plans may need to be about cost-effective, practical limitation and control rather than give an expectation for eradication.

All methods need follow-up over time, starting with the advancing areas first. Given the decades elapsed to arrive at the current levels of coverage on many sites, slowing or reversing the process will be also of necessity long-term, with consistency and persistence from all parties being key.

Various techniques are recommended by [[Natural England]] and the [[RSPB]] to control bracken either individually or in combination [https://web.archive.org/web/20140815035945/http://www.rspb.org.uk/ourwork/farming/advice/details.aspx?id=204253 RSPB Bracken management in the uplands].
* Cutting — Once or twice a year, repeatedly cutting back the fronds for at least 3 years.
* Crushing/rolling —  Using rollers, again for at least 3 years.
* Livestock treading — During winter, encouraging livestock to bracken areas with food. They trample the developing plants and allow frost to penetrate the [[rhizomes]]. In May and June, temporary close grazing or mob stocking on small areas away from nests, particularly using cattle, horses, pigs, or ponies may crush emerging bracken fronds resulting in reduced bracken cover. Sufficient fodder will be required to prevent livestock eating the bracken. This may suit steep areas where human access is difficult and herbicide undesirable.
* Herbicide — [[Asulam]] (also known as Asulox) is selective for ferns; [[glyphosate]] is not; but the latter has the advantage that the effects can be seen soon after application. They are applied when the fronds are fully unfurled to ensure that the chemical is fully absorbed. Rare ferns such as adder's tongue (''[[Ophioglossum vulgatum]]''), killarney (''[[Trichomanes speciosum]]'') and lemon-scented ferns can also be found in similar habitats and it is important that these are not destroyed in the process of bracken control.
[[Natural England]] recommends that only Asulam can be sprayed aerially, Glyphosate requires spot treatment, e.g. using a weedwiper or knapsack spray. The toxicity of Asulam is low and has been generally highly cost-effective but its use is now restricted by the EU after 2012, at least until specific registered uses can be defined.

Selective sprays like Starane, Access, Metsulfuron 600WG, etc. work well but only if sprayed in late autumn so the rhizomes store food for winter and hence absorb the poison.

On archaeological sites, chemical control is usually required as mechanical methods may cause damage.
* Allowing plants to grow in its place, e.g., the establishment of woodland, causes shade that inhibits bracken growth. In the UK, trees, notably rowan, have done well since grazing reduced greatly after the foot-and-mouth epidemic in 2000 but young saplings struggle in high bracken. In decades to come and if permitted, tree shade cover may increase and so may reduce bracken growth, but this is both long-term and in some cases is contentious in the change it would bring to traditionally open heath or moorland, both aesthetically and as a valuable habitat.
* Burning — Useful for removing the litter, but may be counter-productive as bracken is considered to be a fire-adapted species.
* Ploughing — Late in the season followed by sowing seed.

Any bracken control programme must be completed, or bracken will re-establish.

A Bracken Control Group was established in 2012 to provide best-practice guidance for all bracken control techniques. The Group has also been responsible for submitting an application for an Emergency Authorisation to secure the continued availability of Asulam for bracken control, following the decision not to register the product under new regulations in the EU. Registration has been re-applied for but this will not be available until 2017 at the earliest. Until re-registration is approved the Group will aim to keep Asulam available under the emergency provisions.  [http://www.brackencontrol.co.uk Bracken Control Group website]

<gallery>
Image:Adelaarsvaren planten Pteridium aquilinum.jpg|''Pteridium aquilinum''
Image:Tylerfinvold023 bracken ferns.jpg|Fronds of bracken
</gallery>

==In culture==
Bracken is commonly referred to by local populations in the north of England as 'Moorland Scrub'.{{citation needed|date=January 2023}}

The creature ’Bracken’ from the 2023 video game [[Lethal Company]] is named after the plant.
==See also==
* [[List of plants poisonous to equines]]

== References ==
{{Reflist|25em}}
{{Refbegin|colwidth=25em|small=yes}}
* {{cite journal |last1=Marrs |first1=R.H. |last2=Watt |first2=A.S. |year=2006 |title=Biological Flora of the British Isles 245: ''Pteridium aquilinum'' {{small|(L.) Kuhn}} |journal=Journal of Ecology |volume=94 |issue=6 |pages=1272–1321 |doi=10.1111/j.1365-2745.2006.01177.x |s2cid=85114338 }}
* {{cite web |title=''Pteridium aquilinum'' |website=Germplasm Resources Information Network |url=http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?312948 |via=ars-grin.gov |url-status=dead <!-- presumed --> |archive-url=https://web.archive.org/web/20150924144819/http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?312948 |archive-date=2015-09-24}}
* {{cite web |title=''Pteridium aquilinum'' |department=Flora Europaea |website=rbge.org.uk |url=http://rbg-web2.rbge.org.uk/cgi-bin/nph-readbtree.pl/feout?FAMILY_XREF=&GENUS_XREF=Pteridium&SPECIES_XREF=&TAXON_NAME_XREF=&RANK= }}
* {{cite web |title=''Pteridium aquilinum'' |department=Flora of North America |website=efloras.org |url=http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=200003325  }}
{{Refend}}

== External links ==
{{Commons|Pteridium aquilinum}}
* [https://web.archive.org/web/20110608070303/http://homepages.caverock.net.nz/~bj/fern/pteridium.htm World fern species list — ''Pteridium'']
* [https://web.archive.org/web/20020808100202/http://www.rook.org/earl/bwca/nature/ferns/pteridiumaqui.html Independent page devoted to bracken (uses older classification scheme)]
* {{cite journal |vauthors=Alonso-Amelot ME, Avendaño M |title=Human carcinogenesis and bracken fern: a review of the evidence |journal=Curr. Med. Chem. |volume=9 |issue=6 |pages=675–86 |date=March 2002 |pmid=11945131 |url=http://www.benthamdirect.org/pages/content.php?CMC/2002/00000009/00000006/0004C.SGM |doi=10.2174/0929867023370743 |url-status=dead |archive-url=https://web.archive.org/web/20111006102621/http://www.benthamdirect.org/pages/content.php?CMC%2F2002%2F00000009%2F00000006%2F0004C.SGM |archive-date=2011-10-06 }}
* [http://naturalengland.communisis.com/NaturalEnglandShop/product.aspx?ProductID=30f3211f-bc91-4e19-9d74-77b49cc0ba29 Natural England — Bracken control, vegetation restoration and land management]{{dead link|date=November 2016 |bot=InternetArchiveBot |fix-attempted=yes }}
* [https://web.archive.org/web/20140815035945/http://www.rspb.org.uk/ourwork/farming/advice/details.aspx?id=204253 RSPB: Bracken management in the uplands]
* [https://web.archive.org/web/20080720075204/http://www.butterfly-conservation.org/downloads/47/Habitat_Advice.html Bracken for Butterflies] by [[Butterfly Conservation]]
* [http://www.northernbushcraft.com/plants/bracken/notes.htm Edibility of Bracken]: Identification and edible parts of bracken

{{Taxonbar|from=Q258034}}
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[[Category:Dennstaedtiaceae]]
[[Category:Japanese vegetables]]
[[Category:IARC Group 2B carcinogens]]