Rare anti-cancer tree on verge of extinction

The Himalayan mountains are known as a treasure trove of medicinal plants, many of which have not even been scientifically studied. But one rare tree with proven anti-cancer property is on the verge of extinction, and needs urgent protection.

Maire’s yew (Taxus mairei or Lauth Salla in Nepali) is a conifer that used to be abundant in the mountains of central Nepal. Because of unsustainable harvesting, there are less than 500 mature trees left in the wild.

Yews have healing properties for several ailments, but it is for its anti-cancer property that it is most valued, and that is also why the trees are being over-exploited. Their leaves, bark and trunks contain a compound called taxol, proven to inhibit the growth of new cancer cells.

Maire’s yew is one of the three Taxus species found in the country. While Taxus contorta is distributed from west to central Nepal and Taxus wallichiana (Himalayan yew) is found in central to east Nepal. But it is the rarest Taxus mairei is found only in Kavre, Makwanpur and Sindhuli districts in the mountains near Kathmandu Valley.

Taxus mairei is classified as ‘Vulnerable’ in the IUCN red list and categorised and as critically endangered species in Nepal.

However, although poachers and their suppliers harvest them at night to smuggle them out, most local people till recently used to be unaware of its value.

Even though I worked in conservation in Nepal for a decade, I myself had never paid much attention to the diversity of yews in my country. It was only when I was at Oxford surrounded by English yews (Taxus baccata) that I grew curious about the species back home.

This led me to research the mid-mountains of central Nepal in 2018 to estimate wild population of Maire’s yew and harvesting practices of local communities.

I still remember that day clearly: it was raining, we were tired of travelling on a motorbike along a treacherous road in Dhungkharka of Kavre in search of what locals call Lauth Salla.

After six hours, a local farmer pointed us to a stone quarry where a few excavators were busy gouging out a slope. He took us to a tree growing next to a water mill right next to the quarry.

It had dark green needle-like leaves, arranged spirally in two flat rows either side of the stem, and had a pleasant smell. Unlike the Himalayan yew, it had unclear and fewer bud scales. Its bark was covered in dust from the quarry, turning reddish grey from brown and had numerous bruises from being hacked by axes.

We had confirmed our first sighting of Marie’s yew, but seeing how close the excavators were, my joy turned to apprehension. The 300-year old tree clung to a slope with metamorphic rock and the only reason it was still standing was because the locals worshipped the outcrop, believing it to be a manifestation of Lord Shiva.

But after three centuries, it was clear that this tree’s days were numbered. Even faith was unlikely to save it – the quarry was expanding and encroaching on the shrine. The local community seemed to be unaware of the tree’s medicinal property, nor its conservation importance. For them, it was just another old tree.

Upon returning to Kathmandu, we wrote an appeal to save the tree and sent it out to the Kavre district forest office and the prime minister’s staff. Kathmandu’s newspapers wrote about it, and the Division Forest Officer took action to protect the rare tree.

Ten months later, we went back to the site. There was an information board along the path explaining the conservation importance of the tree. A barbed wire fence surrounded the lone tree. The same farmer who had guided us to the site earlier told us how yew tree had now become an attraction, and local people were protecting it.

The yew is just one of the many trees in Nepal and worldwide that are endangered – most without even being studied for their medicinal and other properties. The world has lost 77 tree species to over-exploitation in the last century, and 10% of tree species globally are threatened with extinction.

Nepal’s community forestry program has won international praise for restoring the country’s tree cover and locals have played a remarkable role in the conservation. But the communities are struggling to retain the programs, and reap rewards for their conservation efforts. If allowed to sustainably harvest the leaves of yew trees, the money could be ploughed back into further conservation.

Knowledge about indigenous plant species and their sustainable use can help both the community and nature conservation. Nepal can successfully restore yews in the wild, and reap profits from their commercial cultivation given increasing market demand.

But first, we need to save the last few hundred Maire’s yews that are left.

(This was originally published in Nepali Times)