View source for Biology:Taxus

{{Short description|Genus of conifers in the yew family Taxaceae}}
{{Automatic taxobox
|fossil_range={{fossil range|Early Cretaceous | Recent}}
|image=Taxus baccata MHNT.jpg
|image_caption=''[[Biology:Taxus baccata|Taxus baccata]]'' (European yew) shoot with mature and immature cones
|taxon=Taxus
|authority=[[Biography:Carl Linnaeus|L.]]
| type_species = ''[[Biology:Taxus baccata|Taxus baccata]]''
| type_species_authority = [[Biography:Carl Linnaeus|L.]]
|subdivision_ranks=Species
|subdivision=See text
}}

'''''Taxus''''' is a [[Biology:Genus|genus]] of coniferous [[Earth:Tree|tree]]s or [[Biology:Shrub|shrub]]s known as '''yews''' in the family [[Biology:Taxaceae|Taxaceae]].<ref name="POWO">{{Cite web |title=''Taxus'' L. |url=https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:30068472-2 |website=Plants of the World Online |date=2023 |publisher=Royal Botanic Gardens, Kew |access-date=29 August 2023}}</ref> Yews occur around the globe in temperate zones of the northern hemisphere, northernmost in {{wipe|Norway}} and southernmost in the South Celebes. Some populations exist in tropical highlands.<ref name="GynoDataBase"/>

The oldest known fossil species are from the Early Cretaceous.<ref>{{Cite journal |last1=Xu |first1=Xiao-Hui |last2=Sun |first2=Bai-Nian |last3=Yan |first3=De-Fei |last4=Wang |first4=Jin |last5=Dong |first5=Chong |date=May 2015 |title=A Taxus leafy branch with attached ovules from the Lower Cretaceous of Inner Mongolia, North China |journal=Cretaceous Research |volume=54 |pages=266–282 |doi=10.1016/j.cretres.2014.12.014 |issn=0195-6671}}</ref>

== Morphology ==
[[File:Taxus baccata MHNT seed.jpg|thumb|Seeds of ''Taxus baccata'']]
They are relatively slow-growing and can be very long-lived, and reach heights of {{cvt|2.5|–|20|m|ft}}, with trunk girth averaging {{cvt|5|m|ft}}.<ref>{{cite journal |last1=Moir |first1=Andy |title=The exceptional yew trees of England, Scotland and Wales |journal=Quarterly Journal of Forestry |date=2013 |volume=2013 |issue=2013 |page=187 |url=https://www.academia.edu/5865018 |access-date=19 July 2014 |ref=1}}</ref> They have reddish [[Biology:Bark (botany)|bark]], lanceolate, flat, dark-green [[Biology:Leaf|leaves]] {{cvt|10|–|40|mm|in|frac=4}} long and {{cvt|2|–|3|mm|in|frac=32|abbr=in}} broad, arranged spirally on the stem, but with the leaf bases twisted to align the leaves in two flat rows either side of the stem.<ref name="taxol">{{eFloras|1|132355|Taxus|family=Taxaceae<!-- not currently used, but may be in future -->|first=Matthew H. |last=Hils}}</ref>

The male cones are globose, {{cvt|3|–|6|mm|in|frac=32|abbr=in}} across, and shed their [[Biology:Pollen|pollen]] in early spring. Yews are mostly dioecious, but occasional individuals can be variably monoecious, or change sex with time.<ref name="taxol" />

The [[Conifer cone|seed cones]] are highly modified, each cone containing a single [[Biology:Seed|seed]] {{cvt|4|–|7|mm|in|frac=32|abbr=in}} long partly surrounded by a modified scale which develops into a soft, bright red [[Biology:Berry (botany)|berry]]-like structure called an [[Biology:Aril|aril]], {{cvt|8|–|15|mm|in|frac=32|abbr=in}} long and wide and open at the end. The arils are mature 6–9 months after pollination, and with the seed contained are eaten by [[Biology:Thrush (bird)|thrushes]], [[Biology:Waxwing|waxwing]]s and other [[Biology:Bird|bird]]s, which disperse the hard seeds undamaged in their droppings; maturation of the arils is spread over 2–3 months, increasing the chances of successful seed dispersal.<ref name="taxol" />

== Taxonomy and systematics ==
Taxus is the Latin word for this tree and its wood that is used to make [[Engineering:Javelin|javelin]]s.<ref name="LD">{{cite encyclopedia |url=https://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:1999.04.0059:entry=taxus |title= taxus |last1= Lewis |first1= Charlton T. |last2= Short |first2= Charles |dictionary= A Latin Dictionary |edition= |publisher= Perseus Digital Library |date = 1879 }}</ref> The Latin word is probably borrowed, via Greek {{lang|el|τόξον}} ''tóxon'', from ''taxša'', the Scythian word used for "yew" and "bow"<ref>{{cite web |url=https://www.etymonline.com/word/taxine#etymonline_v_49449 |title=Taxine |date=2019 |website=Online Etymology Dictionary |publisher=Etymonline.com |access-date=January 18, 2019 }}.</ref> (cognate of [[Social:Persian language|Persian]] {{lang|fa|تخش}} ''Taxš'' meaning bow)<ref name="EoIEC">{{cite book |last1=Mallory |first1=J.P. |last2=Adams |first2=D.Q. |date=1997 |title=Encyclopedia of Indo-European Culture |url=https://books.google.com/books?id=tzU3RIV2BWIC&q=yew+bow |location=London [etc.] |publisher=Fitzroy Dearborn |page=78 |isbn=1-884964-98-2}}</ref><ref>Dehk̲h̲udā: Lughat-Nāma. Entry تخش.</ref> because the Scythians [[Biology:Taxus#Uses and traditions|use]] its wood to make their bows.<ref name="EoIEC"/>

All of the yews are very closely related to each other, and some botanists treat them all as subspecies or varieties of just one widespread species; under this treatment, the species name used is ''[[Biology:Taxus baccata|Taxus baccata]]'', the first yew described scientifically.<ref>{{cite web |url=http://www.botanicus.org/page/359061 |title=Caroli Linnaei ... Species plantarum |website=Botanicus.org |access-date=2016-11-17}}</ref>

''Taxus'' species appear similar. Attempts at taxonomy vary from describing all yews as subspecies of ''T.&nbsp;baccata'', as did RKF Pilger in 1903, to splitting species by even very small morphological differences, as did R. W. Spjut in 2007 with 25 species and over 50 varieties. Some species have traditionally been recognized by geographic distribution, but Asian species have been more difficult to classify. ''[[Biology:Taxus contorta|Taxus contorta]]'' in the [[Place:Western Himalaya|Western Himalaya]] and ''[[Biology:Taxus sumatrana|Taxus sumatrana]]'' in [[Biology:Malesia|Malesia]] are now generally agreed upon, but overlapping ranges in the [[Place:Eastern Himalaya|Eastern Himalaya]], {{wipe|China}}, and subtropical southeast Asia have led to greater confusion, with the species ''Taxus chinensis'', ''Taxus mairei'', and ''Taxus wallichiana'' being elucidated only in the 21st century with the aid of [[Biology:Molecular phylogenetics|molecular phylogenetics]].<ref name="GynoDataBase" />

[[File:Taxus globosa foliage.jpg|right|thumb|Foliage of [[Biology:Taxus globosa|Mexican yew]]]]
The most distinct is the Sumatran yew (''T.&nbsp;sumatrana'', native to Sumatra and Celebes north to southernmost {{wipe|China}}), distinguished by its sparse, sickle-shaped yellow-green leaves. The Mexican yew (''Taxus globosa'', native to eastern Mexico south to Honduras) is also relatively distinct with foliage intermediate between Sumatran yew and the other species. The Florida yew, Mexican yew and Pacific yew are all rare species listed as threatened or endangered.{{citation needed|date=January 2023}}

=== Distribution ===
Yews typically occur in the understory or canopy of moist temperate or tropical mountain forests. Elevation varies by latitude from {{cvt|3000|m|ft}} in tropical forests to near sea level in its northernmost populations.<ref name="GynoDataBase">{{Cite web |last=Earle |first=Christopher J. |date=19 May 2020 |title=Taxus (yew) description |url=https://www.conifers.org/ta/Taxus.php |access-date=16 October 2021 |website=The Gymnosperm Database}}</ref>
Yews are common in landscape architecture, giving rise to widespread [[Biology:Naturalisation|naturalized]] populations in the United States. There, both ''T.&nbsp;baccata'' and ''Taxus cuspidata'' are common ornamental shrubs.<ref name="Toxic plants">{{Cite book |title=Toxic plants and other natural toxicants |date=1998 |publisher=CAB International |last1=Garland |first1=Tam |last2=Barr |first2=A. Catherine |others=International Symposium on Poisonous Plants (5th : 1997 : Texas) |isbn=0851992633 |location=Wallingford, England |oclc=39013798}}</ref>

''T.&nbsp;baccata'' appears throughout Europe and into western Asia.<ref name="GynoDataBase" /> ''T.&nbsp;cuspidata'' occurs over much of East Asia, in China, Japan, Korea, and Sakhalin.<ref name="IUCN cuspitdata">{{cite iucn |author1=Katsuki, T |author2=Luscombe, D |name-list-style=amp |year=2013 |title=''Taxus cuspidata'' |journal=The IUCN Red List of Threatened Species |volume=2013 |page=e.T42549A2987373 |url=https://www.iucnredlist.org/species/42549/2987373 |doi=10.2305/IUCN.UK.2013-1.RLTS.T42549A2987373.en |access-date=16 October 2021}}</ref> ''Taxus brevifolia'' ranges in the United States from California to Montana and Alaska,<ref name="Toxic plants" /> while ''Taxus canadensis'' appears in the northeastern United States and southeast Canada.<ref name="GynoDataBase" />
<!--Yews occur worldwide in temperate zones of the northern hemisphere.<ref name="Taxanes in">{{Cite journal |last=Vanhaelen |first=Maurice |last2=Duchateau |first2=Jean |last3=Vanhaelen-Fastré |first3=Renée |last4=Jaziri |first4=Mondher |date=January 2002 |title=Taxanes in Taxus baccata Pollen: Cardiotoxicity and/or Allergenicity? |url=http://www.thieme-connect.de/DOI/DOI?10.1055/s-2002-19865 |journal=Planta Medica |language=en |volume=68 |issue=01 |pages=36–40 |doi=10.1055/s-2002-19865 |issn=0032-0943}}</ref>-->

===Species and hybrids===
[[File:4112 year Yew 3.jpg|thumb|4112 year old ''Taxus'' in [[Earth:Anatolia|Anatolia]]]]

[[Biology:Plants of the World Online|Plants of the World Online]] recognizes 12 confirmed species:<ref name="POWO"/>
{{Div col}}
*''[[Biology:Taxus baccata|Taxus baccata]]'' {{small|L.}}, European yew
*''[[Biology:Taxus brevifolia|Taxus brevifolia]]'' {{small|Nutt.}}, Pacific yew, western yew
*''Taxus calcicola'' {{small|L.M.Gao & Mich.Möller}}, Asian limestone yew
*''[[Biology:Taxus canadensis|Taxus canadensis]]'' {{small|Marshall}}, Canada yew
*''[[Biology:Taxus chinensis|Taxus chinensis]]'' {{small|(Pilg.) Rehder}}, China yew
*''[[Biology:Taxus contorta|Taxus contorta]]'' {{small|Griff.}}, West Himalayan yew
*''[[Biology:Taxus cuspidata|Taxus cuspidata]]'' {{small|Siebold & Zucc.}}, Rigid branch yew, Japanese yew
*''[[Biology:Taxus floridana|Taxus floridana]]'' {{small|Nutt. ex Chapm.}}, Florida yew
*''Taxus florinii'' {{small|Spjut}}, Florin yew
*''[[Biology:Taxus globosa|Taxus globosa]]'' {{small|Schltdl.}}, Mesoamerican yew
*''[[Biology:Taxus mairei|Taxus mairei]]'' {{small|(Lemée & H.Lév.) S.Y.Hu}}, Maire yew
*''[[Biology:Taxus wallichiana|Taxus wallichiana]]'' {{small|Zucc.}}, Wallich yew, East Himalayan yew
{{div col end}}

'''Fossil (extinct) species'''
*{{extinct}}''Taxus engelhardtii'' – Oligocene, Bohemia, twig-leaves, similar to ''T.&nbsp;mairei''<ref name="Kvacek1984">Kvaček, Z. 1984. Tertiary taxads of NW Bohemia. 1982 Acta Univ. Carol., Geol., Pokorny 4: 471–491.</ref><ref name="Spjut2007">{{cite journal |last1=Spjut |first1=R. W. |year=2007 |title=Taxonomy and nomenclature of ''Taxus'' (Taxaceae). A phytogeographical analysis of ''Taxus'' (Taxaceae) based on leaf anatomical characters |journal=J. Bot. Res. Inst. Texas |volume=1 |issue=1 |pages=291–332}} 203–289. ''T.&nbsp;brevifolia'' and ''T.&nbsp;globosa'' var. ''floridana'' thought to evolve from ancestral ''T.&nbsp;globosa'' by loss of stomata and papillae; ''T.&nbsp;canadensis'' recognized in Europe based on leaf fossils from late Tertiary deposits</ref>
*{{extinct}}''Taxus inopinata'' – Upper Miocene, leaf, similar to ''T.&nbsp;baccata''<ref>Corneanu, G. C. , M. Corneanu and R. Bercu. 2004. Comparison between some morpho-anatomical features at fossil vegetal species and at their actual correspondent species. Studia Universitatis Babeş-Bolyai, Geologia, XLIX: 77–84.</ref>
*{{extinct}}''[[Biology:Taxus masonii|Taxus masonii]]'' – Eocene Clarno Formation; Oregon, USA<ref name="Manchester1994">{{Cite journal |last1=Manchester |first1=S.R. |title=Fruits and Seeds of the Middle Eocene Nut Beds Flora, Clarno Formation, Oregon |year=1994 |journal=Palaeontographica Americana |volume=58 |pages=30–31}}</ref>
*{{extinct}}''Taxus schornii'' – Miocene, northern Idaho<ref name="Spjut2007" />

'''Commonly reported hybrids'''

*''[[Biology:Taxus × media|Taxus × media]]'' = ''Taxus baccata'' × ''Taxus cuspidata''<ref>{{cite web |url=http://www.derkleinegarten.de/hecken1_eibe.htm |title=Eibenhecken :-) Pflanzung, Schnitt, Sorten - Taxus baccata |website=Derkleinegarten.de |access-date=2016-11-17}}</ref>
*''Taxus × hunnewelliana'' = ''Taxus cuspidata'' × ''Taxus canadensis''<ref>{{cite web |url=http://www.worldbotanical.com/TAXNA.HTM |title=Overview of the genus Taxus, Taxonomy, Nomenclature, and Ovulate Shoots |website=Worldbotanical.com |access-date=2016-11-17}}</ref>

===Phylogeny===
Below are cladograms showing the evolutionary relationships between yew species and their global distribution.
{| class="wikitable"
|-
! colspan=1 |Möller ''et al.'', 2020<ref name="Repeated intercontaxus">{{cite journal|title=Repeated intercontinental migrations and recurring hybridizations characterise the evolutionary history of yew (Taxus L.)|vauthors=Möller M, Liu K, Li Y, Jian-Hua L, Lin-Jiang Y, Mill R, Thomas P, De-Zhu L, Lian-Ming G|journal=Molecular Phylogenetics and Evolution|date=2020|volume=153|page=106952 |issn=1055-7903|doi=10.1016/j.ympev.2020.106952|pmid=32889136 |s2cid=221503980 }}</ref>
! colspan=1 |Stull ''et al.'', 2021<ref>{{cite journal |last1=Stull |first1=Gregory W. |last2=Qu |first2=Xiao-Jian |last3=Parins-Fukuchi |first3=Caroline |last4=Yang |first4=Ying-Ying |last5=Yang |first5=Jun-Bo |last6=Yang |first6=Zhi-Yun |last7=Hu |first7=Yi  |last8=Ma |first8=Hong |last9=Soltis |first9=Pamela S. |last10=Soltis |first10=Douglas E. |last11=Li |first11=De-Zhu |last12=Smith |first12=Stephen A. |last13=Yi |first13=Ting-Shuang |year=2021 |title=Gene duplications and phylogenomic conflict underlie major pulses of phenotypic evolution in gymnosperms |journal=Nature Plants |url=https://www.nature.com/articles/s41477-021-00964-4 |volume=7 |issue= 8|pages=1015–1025 |doi=10.1038/s41477-021-00964-4|biorxiv=10.1101/2021.03.13.435279 |pmid= 34282286|pmc= |bibcode= |s2cid=232282918 |doi-access=}}</ref>
|- 
| style="vertical-align:top|
{{clade|style=font-size:90%;line-height:80%
|1=''[[Biology:Austrotaxus|Austrotaxus]]''
|2={{clade
  |1=''[[Biology:Pseudotaxus|Pseudotaxus]]''
  |label2='''''Taxus'''''
  |2={{clade
    |1=''[[Biology:Taxus brevifolia|T.&nbsp;brevifolia]]''|style1=background-color:#c9f6ff
    |2={{clade
      |1={{clade|style=background-color:#c9f6ff;|caption=[[Earth:North America|North America]]|captionstyle=background-color:#c9f6ff;text-align:right;font-weight:bold;padding:2px 10px 1px 1px;
        |1=''[[Biology:Taxus globosa|T.&nbsp;globosa]]''|style1=background-color:#c9f6ff
        |2=''[[Biology:Taxus floridana|T.&nbsp;floridana]]''|style2=background-color:#c9f6ff
         }}
      |2={{clade
        |1={{clade
          |1={{clade
            |1=''[[Biology:Taxus canadensis|T.&nbsp;canadensis]]''|style1=background-color:#c9f6ff
            |2=''[[Biology:Taxus cuspidata|T.&nbsp;cuspidata]]''|style2=background-color:#d9ffd4
             }}
          |2={{clade|style=background-color:#d9ffd4|caption=North Eurasia|captionstyle=background-color:#d9ffd4;text-align:right;font-weight:bold;padding:2px 10px 1px 1px;
            |1=''[[Biology:Taxus contorta|T.&nbsp;contorta]]''|style1=background-color:#d9ffd4
            |2=''[[Biology:Taxus baccata|T.&nbsp;baccata]]''|style2=background-color:#d9ffd4
             }}
           }}
        |2={{clade|style=background-color:#fcf1d7;|caption=[[Earth:Eurasia|South Eurasia]]|captionstyle=background-color:#fcf1d7;text-align:right;font-weight:bold;padding:2px 10px 1px 1px;
          |1=''[[Biology:Taxus wallichiana|T.&nbsp;wallichiana]]''
          |2={{clade
            |1={{clade
              |1=''T.&nbsp;Huangshan type''         
              |2=''[[Biology:Taxus chinensis|T.&nbsp;chinensis]]''
               }}
            |2={{clade
              |1=''T.&nbsp;phytonii''
              |2={{clade
                |1=''T.&nbsp;calcicola''
                |2=''[[Biology:Taxus mairei|T.&nbsp;mairei]]''
                 }}
               }}
             }}
           }}
         }}
       }}
     }}
   }}
}}
|
{{clade|style=font-size:90%;line-height:80%
|label1=''Taxus''
|1={{clade
  |1=''[[Biology:Taxus brevifolia|T.&nbsp;brevifolia]]''
  |2={{clade
    |1={{clade
      |1=''[[Biology:Taxus floridana|T.&nbsp;floridana]]''
      |2=''[[Biology:Taxus globosa|T.&nbsp;globosa]]''
       }}
    |2={{clade
      |1=''[[Biology:Taxus wallichiana|T.&nbsp;wallichiana]]''
      |2={{clade
        |1={{clade
          |1={{clade
            |1=''[[Biology:Taxus chinensis|T.&nbsp;chinensis]]''    
            |2=''T.&nbsp;florinii''
             }}
          |2={{clade
            |1=''T.&nbsp;calcicola''
            |2={{clade
              |1=''T.&nbsp;phytonii''
              |2=''[[Biology:Taxus sumatrana|T.&nbsp;sumatrana]]''
               }}
             }}
           }}
        |2={{clade
          |1={{clade
            |1=''[[Biology:Taxus canadensis|T.&nbsp;canadensis]]''
            |2=''[[Biology:Taxus cuspidata|T.&nbsp;cuspidata]]''
             }}
          |2={{clade
            |1=''[[Biology:Taxus baccata|T.&nbsp;baccata]]''
            |2={{clade
              |1=''[[Biology:Taxus mairei|T.&nbsp;mairei]]''
              |2={{clade
                |1=''[[Biology:Taxus contorta|T.&nbsp;contorta]]''
                |2=''[[Biology:Taxus fuana|T.&nbsp;fuana]]''
                 }}
               }}
             }}
           }}
         }}
       }}
     }}
   }}
}}
|}

==Toxicity==

All species of yew contain highly [[Chemistry:Poison|poison]]ous taxine [[Chemistry:Alkaloid|alkaloid]]s, with some variation in the exact formula of the alkaloid between the species. All parts of the tree except the [[Biology:Aril|aril]]s contain the alkaloid. The arils are edible and sweet, but the seed is dangerously [[Chemistry:Poison|poison]]ous; unlike birds, the [[Biology:Human|human]] stomach can break down the seed coat and release the toxins into the body. This can have fatal results if yew 'berries' are eaten without removing the seeds first. Grazing animals, particularly [[Biology:Cattle|cattle]] and [[Biology:Horse|horse]]s, are also sometimes found dead near yew trees after eating the leaves, though [[Biology:Deer|deer]] are able to break down the poisons and will eat yew foliage freely. In the wild, deer browsing of yews is often so extensive that wild yew trees are commonly restricted to cliffs and other steep slopes inaccessible to deer. The foliage is also eaten by the [[Biology:Larva|larva]]e of some [[Biology:Lepidoptera|Lepidoptera]]n [[Biology:Insect|insect]]s including the moth [[Biology:Willow beauty|willow beauty]].{{citation needed|date=January 2023}}
[[File:Taxus baccata MHNT flowers male.jpg|thumb|right|Male (pollen-producing) cones of ''Taxus baccata'']]

===Allergenic potential===

All parts of a yew plant are toxic to humans with the exception of the yew berries (which however contain a toxic seed); additionally, male and dioecious yews in this genus release [[Biology:Cytotoxicity|cytotoxic]] pollen, which can cause headaches, lethargy, aching joints, itching, and skin rashes; it is also a trigger for asthma. These pollen granules are extremely small, and can easily pass through window screens. Male yews bloom and release abundant amounts of pollen in the spring; completely female yews only trap pollen while producing none.<ref name=Ogren>{{cite book |last1=Ogren |first1=Thomas |title=The Allergy-Fighting Garden |date=2015 |publisher=Ten Speed Press |location=Berkeley, CA |isbn=978-1-60774-491-7 |page=205}}</ref>

Yews in this genus are primarily separate-sexed, and males are extremely allergenic, with an OPALS allergy scale rating of 10 out of 10. Completely female yews have an OPALS rating of 1, and are considered "allergy-fighting".<ref name="Ogren" />

== Uses and traditions ==
[[File:ReconstructedOetziAxe.jpg|upright|thumb|A replica of Ötzi's yew and copper axe]]

=== Bows ===
Yew wood is reddish brown (with whiter sapwood), and is very springy. It was traditionally used to make bows, especially the [[Engineering:Longbow|longbow]]. These longbows were used by [[History:Scythians|Scythian]] people who were part of the police force in ancient [[Place:Athens|Athens]]. This use was lent into the [[Social:Ancient Greek|Ancient Greek]] word for "bow"<ref name="EoIEC"/> and later probably borrowed into the Latin word and now generic name of ''Taxus''.

[[Biography:Ötzi|Ötzi]], the Chalcolithic mummy found in 1991 in the Italian Alps, carried an unfinished bow made of yew wood. Consequently, it is not surprising that in Norse mythology, the abode of the god of the bow, [[Religion:Ullr|Ullr]], had the name Ydalir (Yew Dales). Most longbow wood used in northern Europe was imported from [[Place:Iberian Peninsula|Iberia]], where climatic conditions are better for growing the knot-free yew wood required.<ref>{{cite web |url=http://www.iberianature.com/material/yew_spain.htm |title=Yews in Spain |website=www.iberianature.com |access-date=2 April 2018}}</ref> The yew longbow was the critical weapon used by the English in the defeat of the French cavalry at the Battle of Agincourt, 1415. British yews tend to be too gnarly, and thus the wood for English longbows used at the Battle of Agincourt was imported from Spain or northern Italy.<ref>{{cite web |last=Eichhorn |first=Markus |title=Yew – The Sacred Tree |url=http://www.test-tube.org.uk/trees/video_yew.htm |work=Test Tube |publisher=[[Biography:Brady Haran|Brady Haran]] for the [[Organization:University of Nottingham|University of Nottingham]] |date=September 2010}}</ref>

===Cultivation===
It is suggested that English [[Religion:Parish|parish]]es were required to grow yews and, because of the trees' toxic properties, they were grown in the only commonly enclosed area of a village – the churchyard.<ref>{{cite web |title=YEW TREES IN CHURCHYARDS |url=http://www.sacred-texts.com/neu/eng/osc/osc74.htm |website=Sacred-texts.com |access-date=8 August 2011}}</ref> The yew tree can often be found in church graveyards and is symbolic of sadness. Such a representation appears in Lord Alfred Tennyson's poem "In Memoriam A.H.H." (2.61–64).

The yew can be very long-lived. The Fortingall Yew has been considered to be the oldest tree in Europe, at something over 2,000 years old. Tradition has it that [[Religion:Pontius Pilate|Pontius Pilate]] slept under it while on duty before 30 AD. This has been topped by a tree in the churchyard of a small Welsh village called St Cynog. It has been dated to 5,000 years old by dendrologist Janis Fry.<ref>{{cite news |author=David Sanderson |url=http://www.thetimes.co.uk/tto/environment/article4141477.ece |title=Bronze Age tree survives wars (and the builders) to be claimed as Britain's oldest |newspaper=The Times |date=2014-07-08 |access-date=2016-11-17}}</ref> Such old trees usually consist of a circular ring of growths of yew, since their heart has long since rotted away.

The Eihwaz rune is named after the yew, and sometimes also associated with the "evergreen" [[Unsolved:World tree|world tree]], Yggdrasil.

===Horticulture===
[[File:English Yew close 250.jpg|right|thumb|Foliage of Irish yew; note the leaves spreading all round the erect shoots]]
Yews are widely used in landscaping and ornamental [[Earth:Horticulture|horticulture]]. Over 400 [[Biology:Cultivar|cultivar]]s of yews have been named, the vast majority of these being derived from European yew (''Taxus baccata'') or Japanese yew (''Taxus cuspidata''). The hybrid between these two species is [[Biology:Taxus × media|''Taxus'' × ''media'']]. A popular fastigiate selection of the European yew (''Taxus baccata'' 'Fastigiata') is often called the Irish yew, illustrating the difficulties with common names. A few cultivars with yellow leaves are collectively known as golden yews.

===Chemistry===
The Pacific yew (''Taxus brevifolia''), native to the [[Place:Pacific Northwest|Pacific Northwest]] of North America, and the Canada yew (''Taxus canadensis'') of Eastern and Central North America were the initial sources of [[Biology:Paclitaxel|paclitaxel]] or Taxol, a [[Medicine:Chemotherapy|chemotherapeutic]] drug used in [[Medicine:Breast cancer|breast]] and lung cancer treatment and, more recently, in the production of the Taxus drug eluting stent by Boston Scientific. Over-harvesting of the Pacific yew for paclitaxel led to fears that it would become an [[Biology:Endangered species|endangered species]], since the drug was initially extracted from the bark of the yew, the harvesting of which kills the tree.<ref name="Gersmann 2011">{{cite news |last1=Gersmann |first1=Hanna |last2=Aldred |first2=Jessica |title=Medicinal tree used in chemotherapy drug faces extinction |url=https://www.theguardian.com/environment/2011/nov/10/iucn-red-list-tree-chemotherapy |access-date=2017-02-15 |work=The Guardian |date=10 November 2011}}</ref> On January 18, 2008, the [[Biology:Botanic Gardens Conservation International|Botanic Gardens Conservation International]] (representing botanic gardens in 120 countries) stated that "400 medicinal plants are at risk of extinction, from over-collection and deforestation, threatening the discovery of future cures for disease." These included yew trees,<!-- The BGCI article mentions yews in Yunnan Province, China, which is not Pacific yew. --> whose bark is used for the cancer drug [[Biology:Paclitaxel|paclitaxel]].<ref>{{cite news |url=http://news.bbc.co.uk/2/hi/health/7196702.stm |publisher=BBC News |title=Medical plants 'face extinction' |date=19 January 2008}}</ref><ref>{{cite web |url=http://www.bgci.org/news-and-events/news/0479 |title='Miracle' Cures Face Extinction |date=16 January 2008 |publisher=Botanic Gardens Conservation International}}</ref>

However, methods were developed to produce the drug semi-synthetically from the leaves of cultivated European yews. Those can be sustainably harvested without the need to further endanger wild populations, and the Pacific yew is no longer at risk.<ref>{{cite web |publisher=Oregon Biodiversity Information Center |date=2010 |title=Rare, Threatened and Endangered Species of Oregon. Institute for Natural Resources |location=[[Organization:Portland State University|Portland State University]], {{wipe|Portland, Oregon}} |url=http://orbic.pdx.edu/documents/2010-rte-book.pdf |url-status=dead |archive-url=https://web.archive.org/web/20110128214108/http://orbic.pdx.edu/documents/2010-rte-book.pdf |archive-date=2011-01-28}}</ref> The more common Canada yew is also being successfully harvested in northern Ontario, Quebec and New Brunswick, and has become another major source of paclitaxel. Other yew species contain similar compounds with similar biochemical activity. [[Chemistry:Docetaxel|Docetaxel]], an analogue of paclitaxel, is derived from the European yew (''Taxus baccata'').
[[File:Taxus baccata henrykow poland 01.jpg|thumb|Oldest Polish specimen of European yew (1200 years)]]

===In culture===
The yew tree is a frequent symbol in the Christian poetry of [[Biography:T. S. Eliot|T. S. Eliot]], especially his ''Four Quartets''.

==References==
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[[Category:Taxus| ]]
[[Category:Conifer genera]]
[[Category:Dioecious plants]]

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