Summary ⁵

Taxus is a genus of small coniferous trees or shrubs in the yew family Taxaceae. They are relatively slow-growing and can be very long-lived, and reach heights of 2.5–20 metres (8.2–65.6 ft), with trunk girth averaging 5 metres (16 ft). They have reddish bark, lanceolate, flat, dark-green leaves 1–4 centimetres (1⁄2–1 1⁄2 in) long and 2–3 mm (3⁄32–1⁄8 inch) 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.

Uses and traditions ⁵

Yew wood is reddish brown (with whiter sapwood), and is very springy. It was traditionally used to make bows, especially the longbow. 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, Ullr, had the name Ydalir (Yew Dales). Most longbow wood used in northern Europe was imported from Iberia, where climatic conditions are better for growing the knot-free yew wood required. The yew longbow was the critical weapon used by the English in the defeat of the French cavalry at the Battle of Agincourt, 1415. It is suggested that English parishes 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. 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 is considered to be the oldest tree in Europe, at something over 2000 years old. Tradition has it that Pontius Pilate slept under it while on duty before 30 AD. This has recently been topped by a tree in the church yard of a small Welsh Village called St Cynog. It has been dated to 5000 years old by dendrologist Janis Fry. Such old trees usually consist of a circular ring of growths of Yew, since their heart has long since rotted away.

The Eihwazrune is named after the yew, and sometimes also associated with the "evergreen" world tree, Yggdrasil.

Yews are widely used in landscaping and ornamental horticulture. Over 400 cultivars 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 Taxus media. A popular fastigiate selection of the European yew (Taxus baccata 'Fastigiata') is often called the Irish yew, which often complements the fact of the difficulties with common names. A few cultivars with yellow leaves that are being propagated, collectively are known as golden yews, which is another nomenclature blunder.

The Pacific yew (Taxus brevifolia), native to the Pacific Northwest of North America, and the Canada yew (Taxus canadensis) are the sources of paclitaxel or Taxol, a chemotherapeutic drug used in 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 led to fears that it would become an endangered species. However, methods were developed to produce the drug semi-synthetically from cultivated yews, without the need to further endanger the wild populations, and the Pacific yew is not endangered. 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. Docetaxel, an analogue of paclitaxel, is derived from the European yew (Taxus baccata).

The yew tree is a frequent symbol in the Christian poetry of T. S. Eliot, especially his Four Quartets.

On January 18, 2008, the 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, whose bark is used for the cancer drug paclitaxel.

Sources and Credits

1. (c) Even Dankowicz, all rights reserved, uploaded by Even Dankowicz
2. (c) Kim, Hyun-tae, some rights reserved (CC BY), uploaded by Kim, Hyun-tae
3. (c) Hornbeam Arts, some rights reserved (CC BY-NC), https://www.flickr.com/photos/hornbeam/32810091891/
4. (c) .Bambo., some rights reserved (CC BY-NC-SA), https://www.flickr.com/photos/bambolia/1763720311/
5. (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Taxus

More Info

• iNat taxon page
• Biodiversity Heritage Library
• BOLD Systems BIN search
• eFloras.org
• Flora of North America (beta)
• Global Biodiversity Information Facility (GBIF)
• Go Botany
• HOSTS - a Database of the World's Lepidopteran Hostplants
• IPNI (with links to POWO, WFO, and BHL)
• Maryland Biodiversity Project
• NatureServe Explorer 2.0
• SEINet Symbiota portals
• Tropicos
• USDA PLANTS database
• VASCAN by Canadensys
• World Flora Online
• 日本のレッドデータ検索システム
• 植物和名−学名インデックス YList

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