The English Yew Tree, Toxic Compounds and the Ancient Celts
The English Yew Tree has been referred to as the 'Tree of Death'... Read more to discover the story behind this mysterious tree and learn about the connections between the Yew tree, toxic compounds and the Ancient Celts?
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Have you ever heard of the English Yew Tree?
It's scientific name is Taxus baccata
It has also been referred to as the
"Tree of Death",
but first let's learn a bit more about how to recognise an English Yew, you may well have crossed paths with one...
The English Yew is a species of evergreen tree belonging to the conifer family
You may remember from the IDENTIFY SECTION that conifers are GYMNOSPERMS
Leaves are small, straight and needle-like
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Characteristic of conifer trees; think 'pine needles'
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Notice the pointed leaf tips
The male and female flowers generally grow on separate trees
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Botanists would refer to this as being "dioecious"
Unlike most other conifers, seeds of the English Yew tree are NOT within a cone.
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Let's take a closer look at its features:
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Instead each seed is contained in what, at first glance, appears to be a berry...​​
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But we know, from the IDENTIFY Section, that gymnosperms do not produce berries
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Despite appearances this structure is not a berry, but is in fact a 'berry-like' structure - called an "aril"
Where to find it...
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Despite what the name suggests, the English Yew (Taxus baccata) is not restricted to England, although it is native to Britain, it can be found across most of Europe, as well as in parts of Northern Africa.
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In the UK, it is commonly found across the South of England
Yew Trees in Woodlands
English Yew trees form part of the understory in beech woodland ecosystems.
It also provides a source of food for various creatures:
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The arils are eaten by certain birds and small mammals
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The leaves are eaten by caterpillars of the satin beauty moth
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It can also be used to form dense Yew hedges, which provide many birds with protection and nesting spots.
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Including magnificent species such as the Firecrest and Goldcrest
Yew Trees in... Churchyards?
Aside from woodlands and hedges, another place that English Yew trees are commonly found is in churchyards...
Aside for woodlands and hedges, another place that English Yew trees are commonly found is in churchyards…
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In England, there are at least 500 churchyards that contain Yew trees. In fact, many of the Yew trees are older than the church buildings...
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Some are even believed to predate the 10th Century!
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Let's go back in time... to the Ancient Celts!
If we turn back time, before the establishment of Christian churches, we arrive at the time of the Ancient Celts... but what do the Celts have to do with our plant of interest?
You might have heard of ‘Druids’?
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Druids are thought to have been the most highly respected members of a Celtic community.
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Among many other roles, they were also religious / spiritual leaders of Celtic communities.
Historians think that the Yew tree was considered sacred by the Druids
Remember that reference to the 'Tree of Death'?
This belief was adopted into Christian beliefs to some degree:
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It was thought that planting Yew trees on the graves of plague victims would purify and protect the deceased
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For many centuries, yew branches were part of traditions at funerals and on Palm Sunday.
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In Ireland, the Irish Yew was said to be ‘the coffin of the vine’
It seems that as well as being symbolic of everlasting life and rebirth, as can be seen in its nature as an evergreen tree, the Yew also came to symbolise death and resurrection for the Ancient Celts.
Toxic Compounds and Life-Saving Medicine
For centuries, people have also been using Yew trees for different purposes:
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For crafting tools, furniture, musical instruments, etc.
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Yew wood was used to make longbows and crossbows during the Middle Ages
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One of the World’s oldest surviving wooden artefacts is a spear head made from Yew, known as the "Clacton spear"
Another compelling use of the Yew tree lies in its medicinal potential...
With the partial exception of the red arils, most parts of the Yew tree are HIGHLY POISONOUS
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They contain toxic compounds called taxines - hence the scientific name 'Taxus'.
More specifically, compounds called taxanes are contained within the leaves and bark of the Yew – these compounds have been used to develop important medication:
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Such as Pacitaxel (brand name "Taxol") which is used in chemotherapy treatment for some forms of cancer.
Harvesting of Yew tree parts for medicine
Originally, these compounds were isolated from the bark of the the Pacific Yew (Taxus brevifolia)
However, Yew trees are slow-growing, and the process of removing bark kills the tree.
Harvesting in this way was detrimental to populations of Yew trees. The process was gravely unsustainable.
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Researchers looked into related species of Pacific Yew, to find the same or similarly active compounds
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This led to the method of extracting chemicals from leaf clippings of Taxus baccata
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This could then be processed to produce the drug Pacitaxel – a slightly more sustainable method than extraction from bark.
Since then, more advanced methods have been developed...
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Fortunately, Paclitaxel can now be produced by using cultured plant cells on an industrial scale in laboratories
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Harvesting large amounts of leaves and/or bark of the Yew tree is no longer necessary for medicine production, avoiding the issue of overexploitation!
How did they try to counter this issue?
This story all began with the humble Yew tree - this so-called 'Tree of Death' actually led to the development of life-saving medicine!
Protecting Indigenous Peoples and their Knowledge
In many cases, plants with medicinal properties have a history of use in traditional medicine by communities of Indigenous Peoples living in/near their ancestral lands/forests.
Just as it is important to protect nature, it is also important to ensure protection of communities of Indigenous Peoples within and near their ancestral land.
It is also important to appreciate traditional knowledge when it comes to appreciating the power and uses of plants.
Prior to the development of the anti-cancer drug, Paclitaxel, traditional remedies utilising the Himalayan Yew had already been used by various native communities for treating cold, common fever and other ailments.​
References:
Woodland Trust. Available at: https://www.woodlandtrust.org.uk/trees-woods-and-wildlife/british-trees/a-z-of-british-trees/yew/ (Accessed 25 November 2020)
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Harrison Mellor, K. (2018) 'Ancient yew trees: the UK's oldest yews' Woodland Trust, 22 January. Available at: https://www.woodlandtrust.org.uk/blog/2018/01/ancient-yew-trees/ (Accessed 25 November 2020)
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Kew. Available at: https://www.kew.org/plants/yew (Accessed 25 November 2020)
Juyal, D., Thawani, V., Thaledi, S., Joshi, M. (2014) 'Ethnomedical Properties of Taxus Wallichiana Zucc. (Himalayan Yew)', Journal of Traditional and Complementary Medicine, 4(3), pp. 159-160. doi: 10.4103/2225-4110.136544.
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Harrison, C., Gardiner, L. (2016) Bizzare Botany: An A-Z Adventure through the Plant Kingdom. Surrey: Royal Botanic Gardens, Kew, pp. 161.