Yamdal (Himalayan Yew)

Taxus contorta (Himalayan Yew)

Vernacular name: Brey (in Kinnauri)

Click here to watch a short video about this species

Click here to watch a short video about this species

Taxus contorta (previously - Taxus wallichiana), commonly known as Himalayan Yew (or Yamdal in Kinnauri), is listed as an endangered species on the IUCN Red List of Threatened Species. Native to the Himalayas (India, Nepal, Bhutan, China) and Southeast Asia, this evergreen tree species thrives in cold temperate montane regions at elevations ranging from 900 m to 3,700 m. The endangered status of this species was last assessed in 2010, and revealed a declining population trend. It is a dioecious gymnosperm, meaning male and female reproductive parts grow on different trees, and reproduction occurs through exposed seeds instead of flowers. 

Why is this tree species endangered?

• Trees of the Taxus genus are known for their "anti-cancer properties" due to a compound called "Paclitaxel" (brand name Taxol®), found in the bark. Paclitaxel is widely used in chemotherapy to treat breast, ovarian, and lung cancers. However, harvesting the bark often kills the tree, and high demand for the compound has severely impacted the tree's population, contributing to its endangered status.

• This tree species is also extremely sensitive to drought and requires abundant rainfall, a cold temperate montane/submontane climate, and shade to thrive. Once the natural populations are disturbed, their recovery becomes even more challenging due to these specific environmental requirements.
  

Are there other sources of the 'Prized Paclitaxel’?

The first extraction of paclitaxel came from the bark of the Pacific yew (Taxus brevifolia), another tree species in the same genus. To meet growing demand, scientists later began synthesizing paclitaxel using the tree's leaves, although this required additional extraction steps. In 1993, paclitaxel was also discovered in an endophytic fungus (Taxomyces andreanae) living in the yew tree. Over time, more such fungal sources were identified. However, using these fungi for extraction remains rare in the pharmaceutical industry, as the process is more complex, time-consuming, and resource-intensive, which limits profitability.

Protective legislations in India

In India, Taxus contorta (Himalayan Yew), is listed under Schedule III of the Wildlife Protection Act (WLPA) of 1972. This schedule prohibits the collection, sale, or trade of these plants without a permit. However, demand in the black market continues to threaten this tree species.

In local culture

• Traditionally, locals in Kinnaur collect the bark from the Taxus contorta tree, dry it, and use it to make salt tea. However, excessive bark removal can harm or even kill the tree. This issue can be circumvented by harvesting the bark only from the branches to ensure the tree's survival–as was once suggested to me by a local shepherdess.

• Within the Unani system of traditional medicine, Taxus leaves are used to prepare “zarnab”, a drug that is locally used for treating cardiac disorders.

  
  

Disturbing figures

• The Taxus genus is part of the Taxaceae family, which has 8 known genera, 2 of which are already extinct. 

• Genetic studies on Taxus contorta show low diversity, indicating the vulnerability of the species to climate change and deforestation.

• Distribution studies conducted in 2013 found no seedlings or saplings of the species in the Western Himalayan region, and reported at least 11% of trees showing complete bark removal, signaling a decline in natural population.

The need to protect the Himalayan yew tree has never been more urgent.

References

1. Gallego-Jara, J., et al. (2020). A comprehensive review about Taxol®: History and future challenges. Molecules, 25(24), 5986.

2. Rathore, P., Roy, A., & Karnatak, H. (2019). Modelling the vulnerability of Taxus wallichiana to climate change scenarios in South East Asia. Ecological Indicators, 102, 199-207.

3. Uniyal, S. K. (2013). Bark removal and population structure of Taxus wallichiana Zucc. in a temperate mixed conifer forest of western Himalaya. Environmental Monitoring and Assessment, 185, 2921-2928.

4. Mohapatra, K. P., et al. (2009). Genetic analysis and conservation of endangered medicinal tree species Taxus wallichiana in the Himalayan region. New Forests, 37, 109-121.

5. Chemistry and Biology of Taxol. (1994).

Link to instagram video: https://www.instagram.com/reel/DGZuduFTQOC/?igsh=MTI3eTBldGk0YnZpbQ%3D%3D