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{{Taxobox
| color = lightgreen
| name = ''Taxus''
| image = TXbaccata.jpg
| image_width = 240px
| image_caption = ''Taxus baccata'' (European Yew) shoot with <br>mature and immature cones
| regnum = [[Plant]]ae
| divisio = [[Pinophyta]]
| classis = [[Pinophyta|Pinopsida]]
| ordo = [[Pinales]]
| familia = [[Taxaceae]]
| genus = '''''Taxus'''''
| genus_authority = [[Carolus Linnaeus|L.]]
| subdivision_ranks = Species
| subdivision =
''[[Taxus baccata]]'' - European Yew<br>
''[[Taxus brevifolia]]'' - Pacific (or Western) Yew<br>
''[[Taxus canadensis]]'' - Canadian Yew<br>
''[[Taxus chinensis]]'' - Chinese Yew<br>
''[[Taxus cuspidata]]'' - Japanese Yew<br>
''[[Taxus floridana]]'' - Florida Yew<br>
''[[Taxus globosa]]'' - Mexican Yew<br>
''[[Taxus sumatrana]]'' - Sumatran Yew<br>
''[[Taxus wallichiana]]'' - Himalayan Yew
}}
'''''Taxus''''' is a [[genus]] of yews, small [[Pinophyta|coniferous]] [[tree]]s or [[shrub]]s in the yew family [[Taxaceae]]. They are relatively slow growing and can be very long-lived, and reach heights of 1-40 m, with trunk diameters of up to 4 m. They have reddish [[bark]], lanceolate, flat, dark-green [[leaf|leaves]] 1-4 cm long and 2-3 mm 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.
[[Image:YewSeed.jpg|left|thumb|European Yew cone (detail)]]
The [[conifer cone|seed cones]] are highly modified, each cone containing a single [[seed]] 4-7 mm long partly surrounded by a modified scale which develops into a soft, bright red [[berry]]-like structure called an [[aril]], 8-15 mm 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 [[Thrush (bird)|thrushes]], [[waxwing]]s and other [[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. The male cones are globose, 3-6 mm diameter, and shed their [[pollen]] in early spring. Yews are mostly [[Plant sexuality|dioecious]], but occasional individuals can be variably [[Plant sexuality|monoecious]], or change sex with time.
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 ''Taxus baccata'', the first yew described scientifically.
[[Image:MexYew.jpg|left|thumb|Foliage of Mexican Yew]]
The most distinct is the Sumatran Yew (''T. sumatrana'', native from [[Sumatra]] and [[Celebes]] north to southernmost [[China]]), distinguished by its sparse, sickle-shaped yellow-green leaves. The Mexican Yew (''T. 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.
All species of yew contain highly [[poison]]ous [[alkaloid]]s known as [[taxane]]s, with some variation in the exact formula of the alkaloid between the species. All parts of the tree except the arils contain the alkaloid. The arils are edible and sweet, but the seed is dangerously [[poison]]ous; unlike birds, the [[human]] stomach can break down the seed coat and release the taxanes into the body. This can have fatal results if yew 'berries' are eaten without removing the seeds first. Grazing animals, particularly [[cattle]] and [[horse]]s, are also sometimes found dead near yew trees after eating the leaves, though [[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 [[larva]]e of some [[Lepidoptera]]n [[insect]]s including [[Willow Beauty]].
[[Image:Taxus baccata flowers.jpg|thumb|right|Male cones of ''Taxus baccata'']]
===Uses and traditions===
Yew [[wood]] is reddish brown (with whiter sapwood), and is very springy. It was traditionally used to make [[bow (weapon)|bows]], especially the [[longbow]]. [[Ötzi]], the Chalcolithic [[mummy]] found in 1991 in the Austrian alps, carried an unfinished longbow made of yew wood. Consequently, it is not surprising that, in [[Norse mythology]], the god of the bow, [[Ullr]]'s abode had the name [[Ydalir]] (Yew dales). Most longbow wood used in northern Europe was imported from [[Iberian Peninsula|Iberia]], where climatic conditions are better for growing the knot-free yew wood required. The [[Eihwaz]] [[rune]] ᛇ is named after the yew, and sometimes also associated with the "evergreen" [[World tree]], [[Yggdrasil]].
[[image: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 [[horticulture]]. Over 400 [[cultivar]]s of yews have been named, the vast majority of these being derived from European Yew, Japanese Yew and the hybrid between them (''Taxus x media''). The most popular of these are the "Irish Yew" (''Taxus baccata'' 'Fastigiata'), a fastigiate cultivar of the European Yew, and the several variants with yellow leaves, collectively known as golden yew.
The Pacific Yew ''Taxus brevifolia'', native to the [[Pacific Northwest]] of [[North America]], and Canada Yew ''Taxus canadensis'' are the sources of [[paclitaxel]], a [[chemotherapy|chemotherapeutic]] drug used in [[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 this drug has resulted in it becoming an [[endangered species]], though the drug is now produced semi-synthetically from cultivated yews, without the need to further endanger the wild populations. The more common Canada yew, ''Taxus canadensis'', is also being successfully harvested in northern [[Ontario]], [[Québec]] and [[New Brunswick]], and has become another major source of paclitaxel. Other yew species contain similar compounds with similar biochemical activity. [[Docetaxel]], an analogue of paclitaxel, is derived from the ''Taxus baccata''.
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 tree is a frequent symbol in the Christian poetry of [[T. S. Eliot]], especially his ''[[Four Quartets]]''.
[[Image:Taxus_baccata_henrykow_poland_01.jpg|right|thumb|oldest polish taxus baccata(1200 years) (detail)]]
[[Category:Taxaceae]]
| color = lightgreen
| name = ''Taxus''
| image = TXbaccata.jpg
| image_width = 240px
| image_caption = ''Taxus baccata'' (European Yew) shoot with <br>mature and immature cones
| regnum = [[Plant]]ae
| divisio = [[Pinophyta]]
| classis = [[Pinophyta|Pinopsida]]
| ordo = [[Pinales]]
| familia = [[Taxaceae]]
| genus = '''''Taxus'''''
| genus_authority = [[Carolus Linnaeus|L.]]
| subdivision_ranks = Species
| subdivision =
''[[Taxus baccata]]'' - European Yew<br>
''[[Taxus brevifolia]]'' - Pacific (or Western) Yew<br>
''[[Taxus canadensis]]'' - Canadian Yew<br>
''[[Taxus chinensis]]'' - Chinese Yew<br>
''[[Taxus cuspidata]]'' - Japanese Yew<br>
''[[Taxus floridana]]'' - Florida Yew<br>
''[[Taxus globosa]]'' - Mexican Yew<br>
''[[Taxus sumatrana]]'' - Sumatran Yew<br>
''[[Taxus wallichiana]]'' - Himalayan Yew
}}
'''''Taxus''''' is a [[genus]] of yews, small [[Pinophyta|coniferous]] [[tree]]s or [[shrub]]s in the yew family [[Taxaceae]]. They are relatively slow growing and can be very long-lived, and reach heights of 1-40 m, with trunk diameters of up to 4 m. They have reddish [[bark]], lanceolate, flat, dark-green [[leaf|leaves]] 1-4 cm long and 2-3 mm 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.
[[Image:YewSeed.jpg|left|thumb|European Yew cone (detail)]]
The [[conifer cone|seed cones]] are highly modified, each cone containing a single [[seed]] 4-7 mm long partly surrounded by a modified scale which develops into a soft, bright red [[berry]]-like structure called an [[aril]], 8-15 mm 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 [[Thrush (bird)|thrushes]], [[waxwing]]s and other [[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. The male cones are globose, 3-6 mm diameter, and shed their [[pollen]] in early spring. Yews are mostly [[Plant sexuality|dioecious]], but occasional individuals can be variably [[Plant sexuality|monoecious]], or change sex with time.
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 ''Taxus baccata'', the first yew described scientifically.
[[Image:MexYew.jpg|left|thumb|Foliage of Mexican Yew]]
The most distinct is the Sumatran Yew (''T. sumatrana'', native from [[Sumatra]] and [[Celebes]] north to southernmost [[China]]), distinguished by its sparse, sickle-shaped yellow-green leaves. The Mexican Yew (''T. 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.
All species of yew contain highly [[poison]]ous [[alkaloid]]s known as [[taxane]]s, with some variation in the exact formula of the alkaloid between the species. All parts of the tree except the arils contain the alkaloid. The arils are edible and sweet, but the seed is dangerously [[poison]]ous; unlike birds, the [[human]] stomach can break down the seed coat and release the taxanes into the body. This can have fatal results if yew 'berries' are eaten without removing the seeds first. Grazing animals, particularly [[cattle]] and [[horse]]s, are also sometimes found dead near yew trees after eating the leaves, though [[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 [[larva]]e of some [[Lepidoptera]]n [[insect]]s including [[Willow Beauty]].
[[Image:Taxus baccata flowers.jpg|thumb|right|Male cones of ''Taxus baccata'']]
===Uses and traditions===
Yew [[wood]] is reddish brown (with whiter sapwood), and is very springy. It was traditionally used to make [[bow (weapon)|bows]], especially the [[longbow]]. [[Ötzi]], the Chalcolithic [[mummy]] found in 1991 in the Austrian alps, carried an unfinished longbow made of yew wood. Consequently, it is not surprising that, in [[Norse mythology]], the god of the bow, [[Ullr]]'s abode had the name [[Ydalir]] (Yew dales). Most longbow wood used in northern Europe was imported from [[Iberian Peninsula|Iberia]], where climatic conditions are better for growing the knot-free yew wood required. The [[Eihwaz]] [[rune]] ᛇ is named after the yew, and sometimes also associated with the "evergreen" [[World tree]], [[Yggdrasil]].
[[image: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 [[horticulture]]. Over 400 [[cultivar]]s of yews have been named, the vast majority of these being derived from European Yew, Japanese Yew and the hybrid between them (''Taxus x media''). The most popular of these are the "Irish Yew" (''Taxus baccata'' 'Fastigiata'), a fastigiate cultivar of the European Yew, and the several variants with yellow leaves, collectively known as golden yew.
The Pacific Yew ''Taxus brevifolia'', native to the [[Pacific Northwest]] of [[North America]], and Canada Yew ''Taxus canadensis'' are the sources of [[paclitaxel]], a [[chemotherapy|chemotherapeutic]] drug used in [[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 this drug has resulted in it becoming an [[endangered species]], though the drug is now produced semi-synthetically from cultivated yews, without the need to further endanger the wild populations. The more common Canada yew, ''Taxus canadensis'', is also being successfully harvested in northern [[Ontario]], [[Québec]] and [[New Brunswick]], and has become another major source of paclitaxel. Other yew species contain similar compounds with similar biochemical activity. [[Docetaxel]], an analogue of paclitaxel, is derived from the ''Taxus baccata''.
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 tree is a frequent symbol in the Christian poetry of [[T. S. Eliot]], especially his ''[[Four Quartets]]''.
[[Image:Taxus_baccata_henrykow_poland_01.jpg|right|thumb|oldest polish taxus baccata(1200 years) (detail)]]
[[Category:Taxaceae]]
