Taxus wallichiana

Taxus wallichiana
Scientific classification
Kingdom: Plantae
Division: Pinophyta
Class: Pinopsida
Order: Pinales
Family: Taxaceae
Genus: Taxus
Species: T. wallichiana
Binomial name
Taxus wallichiana
Zucc.
Synonyms

Taxus baccata subsp. wallichiana
Taxus yunnanensis[2]

Taxus wallichiana, the Himalayan yew, is a species of yew, native to the Himalaya and parts of south-east Asia. The species has a variety of uses in traditional medicine. It is currently classfied as endangered by the IUCN.

Distribution and habitat

The Himalayan yew is found in China (Yunnan and Sichuan), Tibet, Nepal, Bhutan, India (Arunachal Pradesh, Assam), Myanmar, and some parts of Viet Nam. It is also present in the Philippines, Sulawesi and Sumatra. The species favours a reasonably wide range of habitats, growing in montane, temperate, warm temperate, and tropical submontane to high montane forests which may be deciduous, evergreen, or of mixed character. In forests, it tends to present as a low canopy tree; in open situations it usually forms a large, broadly spreading shrub. Elevation ranges from 900 m to 3,700 m.[1]

Growth

It is a medium-sized evergreen coniferous tree growing to 20 m tall, similar to Taxus baccata and sometimes treated as a subspecies of it. The shoots are green at first, becoming brown after three or four years. The leaves are thin, flat, slightly falcate (sickle-shaped), 1.5–2.7 cm long and 2 mm broad, with a softly mucronate apex; they are arranged spirally on the shoots but twisted at the base to appear in two horizontal ranks on all except for erect lead shoots. It is dioecious, with the male and female cones on separate plants; the seed cone is highly modified, berry-like, with a single scale developing into a soft, juicy red aril 1 cm diameter, containing a single dark brown seed 7 mm long. The pollen cones are globose, 4 mm diameter, produced on the undersides of the shoots in early spring.[3]

Species

Similar plants occurring further east through China to Taiwan, Vietnam and the Philippines are included in Taxus wallichiana as T. wallichiana var. chinensis (Pilger) Florin by some authors,[2] but are more often treated as a separate species Taxus chinensis.[4][3]

Medicinal uses

The tree has medicinal use in Ayurveda and Tibetan medicine. Taxus wallichiana is also a source of the chemical precursors to the anticancer drug paclitaxel.[5] Taxus wallichiana is used for making tea by the Bhotiya tribal community in the Garhwal Himalaya. The stem bark of this species, which is locally known as thuner, is collected for this purpose. This species is also used as fuelwood by the local communities. In Himachal it is known to be medicine for some types of cancer.[6]

Conservation

The Himalayan yew has been subject to heavy exploitation for its leaves and bark across most of its range through the Himalayas and western China. Declines have been particularly heavy in India and Nepal, with losses of up to 90% having been reported. The degree of exploitation in other locations in its range is less well known, but is also assumed to be serious. The species is currently classfied as endangered by the IUCN. It is present in several protected areas, and at least some conservation and propagation measures are underway, with an eye to its commercial value in the medicine trade.[1]

References

  1. 1 2 3 Thomas, P. & Farjon, A. 2011 (2011). "Taxus wallichiana". IUCN Red List of Threatened Species (IUCN) 2011: e.T46171879A9730085. Retrieved 6 December 2015.
  2. 1 2 "Flora of China: Taxus wallichiana var. wallichiana". eFloras.org.
  3. 1 2 Rushforth, K. (1987). Conifers. Helm ISBN 0-7470-2801-X.
  4. ↑ Farjon, A. (1998). World Checklist and Bibliography of Conifers. Royal Botanic Gardens, Kew ISBN 1-900347-54-7.
  5. ↑ Medicinal plants on verge of extinction - environment - 10 January 2009 - New Scientist
  6. ↑ Kala, C.P. (2010). Medicinal Plants of Uttarakhand; Diversity, Livelihood and Conservation. Delhi: BioTech Books. p. 188. ISBN 8176222097.

Further reading

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