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Taxus brevifolia
Taxus brevifolia (Pacific Yew) foliage
Conservation status
Scientific classification
Kingdom: Plantae
Division: Pinophyta
Class: Pinopsida
Order: Pinales
Family: Taxaceae
Genus: Taxus
Species: T. brevifolia
Binomial name
Taxus brevifolia
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, most notably occuring on Zuckerberg Island near Castlegar and south to central Idaho.

Contents

Characteristics

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. In some instances, trees with heights in excess of 20m occur in parks and other protected areas, quite often in gullies. The tree is extremely slow growing, and has a habit of rotting from the inside, creating hollow forms. This makes it difficult to impossible to make accurate rings counts to determine a specimens true age. Often damaged by succesion of the forest, it usually ends up in a squat, multiple leader form.

It has thin scaly brown bark, covering a thin layer of off-white sap wood with a darker heartwood that varies in color from brown to a magenta/purplish hue.. 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.

Discovery of taxol

The chemotherapy drug paclitaxel (Taxol), 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.[1]

Gallery

References

Notes

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Wikispecies

Up to date as of January 23, 2010

From Wikispecies

Taxus brevifolia

Taxonavigation

Main Page
Cladus: Eukaryota
Regnum: Plantae
Division: Pinophyta
Classis: Pinopsida
Ordo: Pinales
Familia: Taxaceae
Genus: Taxus
Species: Taxus brevifolia

Name

Taxus brevifolia Nutt., N. Amer. Sylv. 3: 86. 1849.

Synonyms

Homotypic
  • Taxus baccata subsp. brevifolia (Nutt.) Pilger, Planzenreich 4(5): 113. 1903.
  • Taxus baccata var. brevifolia (Nutt.) Koehne, Deutsche Dendrol. 6. 1893.
  • Taxus brevifolia var. polychaeta Spjut, J. Bot. Res. Inst. Texas 1 (1): 217. 2007.
  • Taxus brevifolia var. reptaneta Spjut, J. Bot. Res. Inst. Texas 1 (1): 219. 2007.

References

  • Data compiled from various sources by Mark W. Skinner. National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

Vernacular names

English: Pacific yew
Suomi: lännenmarjakuusi
Wikimedia Commons For more multimedia, look at Taxus brevifolia on Wikimedia Commons.

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