Taxus brevifolia


Taxus brevifolia

Taxobox
name = "Taxus brevifolia"
status = LR/nt | status_system = IUCN2.3



image_width = 240px
image_caption = "Taxus brevifolia" (Pacific Yew) foliage
regnum = Plantae
divisio = Pinophyta
classis = Pinopsida
ordo = Pinales
familia = Taxaceae
genus = "Taxus"
species = "T. brevifolia"
binomial = "Taxus brevifolia"
binomial_authority = Nutt.

"Taxus brevifolia" (Pacific Yew or Western Yew) is a conifer native to the Pacific Northwest of North America. It ranges from southernmost Alaska south to central California, mostly in the Pacific Coast Ranges, but with an isolated disjunct population in southeast British Columbia and south to central Idaho.

It is a small to medium-sized evergreen tree, growing 10-15 m tall and with a trunk up to 50 cm diameter, rarely more.

It has thin scaly brown bark. The leaves are lanceolate, flat, dark green, 1-3 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 except on erect leading shoots where the spiral arrangement is more obvious.

The 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 thrushes and other birds, 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. It is mostly dioecious, but occasional individuals can be variably monoecious, or change sex with time.

Uses

The chemotherapy drug paclitaxel, used in breast, ovarian and lung cancer treatment, is derived from "Taxus brevifolia". As it was already becoming increasingly scarce when its chemotherapeutic potential was realized, the Pacific Yew was never commercially harvested from its habitat in the large scale; the widespread use of the paclitaxel was enabled when a semi-synthetic pathway was developed from extracts of cultivated yews of other species. Unlicenced pharmaceutical production use of closely-related wild yew species in India and China may be threatening some of those species. [Citation
last = BGCI
first =
title = ‘Miracle’ Cures Face Extinction
url=http://www.bgci.org/medicinal/2040
accessdate = 2008-07-21
]

References

* [http://culturesheet.org/taxaceae:taxus:brevifolia Taxus brevifolia] on CultureSheet.org
*
* Heiken, D. (1992). The Pacific Yew and Taxol: Federal management of an emerging resource. "Journal of Environmental Law and Litigation" 7: 175.
* [http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233501253 Flora of North America: "Taxus brevifolia"] [http://www.efloras.org/object_page.aspx?object_id=7082&flora_id=1 Range
]
* [http://www.na.fs.fed.us/spfo/pubs/silvics_manual/volume_1/taxus/brevifolia.htm US Forest Service Silvics Manual: "Taxus brevifolia"]
* [http://www.fs.fed.us/global/iitf/pdf/shrubs/Taxus%20brevifolia.pdf US Forest Service: "Taxus brevifolia"] (pdf file)
* [http://www.botgard.ucla.edu/html/botanytextbooks/economicbotany/Taxus/index.html UCLA text on "Economic Botany"]

Notes


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  • Taxus brevifolia — Yew Yew, n. [OE. ew, AS. e[ o]w, [=i]w, eoh; akin to D. ijf, OHG. [=i]wa, [=i]ha, G. eibe, Icel. [=y]r; cf. Ir. iubhar, Gael. iubhar, iughar, W. yw, ywen, Lith. j[ e]va the black alder tree.] [1913 Webster] 1. (Bot.) An evergreen tree ({Taxus… …   The Collaborative International Dictionary of English

  • Taxus brevifolia — ID 82839 Symbol Key TABR2 Common Name Pacific yew Family Taxaceae Category Gymnosperm Division Coniferophyta US Nativity Native to U.S. US/NA Plant Yes State Distribution AK, CA, ID, MT, NV, OR, WA Growth Habit Tree …   USDA Plant Characteristics

  • Taxus brevifolia — noun small or medium irregularly branched tree of the Pacific coast of North America; yields fine hard close grained wood • Syn: ↑Pacific yew, ↑California yew, ↑western yew • Hypernyms: ↑yew • Member Holonyms: ↑Taxus, ↑ …   Useful english dictionary

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  • Taxus brevifolia Nutt. — Symbol TABR2 Common Name Pacific yew Botanical Family Taxaceae …   Scientific plant list

  • Taxus baccata — (European Yew) shoot with mature and immature cones Conservation status …   Wikipedia

  • Taxus — Taxobox name = Taxus image width = 240px image caption = Taxus baccata (European Yew) shoot with mature and immature cones regnum = Plantae divisio = Pinophyta classis = Pinopsida ordo = Pinales familia = Taxaceae genus = Taxus genus authority =… …   Wikipedia


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