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Taxus baccata, yew
Rich in myths, legends and folklore. The berries are a good example of why advising a child to always chew its food thoroughly is not universally sound.
Read more about Taxus baccata, yew, in these blog entries;
'Poisonous Plants 1-2-1' video about yew
Some local folklore about yew and the devil
What decides whether a plant gets into a list of 'most poisonous'?
A Remembrance Day look at plants associated with war and soldiers
Paclitaxel no longer depends on people providing yew clippings
Plants and trees in a public park
The yew in Gilbert White's garden
Taxus baccata, yew
Meaning of the Name
Possibly from the Greek ‘taxon’, ‘bow’ as a result of the use of its wood to make bows. Persian has ‘tachš’ for ‘bow’. A mummy from the Chalcolithic age, around 4000BC, was found with an unfinished bow made of yew so its use for this purpose goes back much further than the English long bowmen usually associated with it.
From Latin ‘bacca’, ‘berry’
Common Names and Synonyms
yew, Irish yew, English yew
How Poisonous, How Harmful?
Taxus baccata, yew
All parts, except the flesh of the berries, contain taxin(e) a complex of alkaloids which is rapidly absorbed. Also present are ephedrine, a cyanogenic glycoside (taxiphyllin) and a volatile oil.
Where poisoning does occur, in animals or humans, there may be no symptoms and death may follow within a few hours of ingestion. If symptoms do occur, they include trembling, staggering, coldness, weak pulse and collapse.
Yew is one of the plants where the poison is not destroyed when the plant dies. Thus, branches removed from a yew by high winds or pruning will retain their poison.
Though the berries are harmless, the seed within is highly toxic. Unbroken it will pass through the body without being digested but if the seed is chewed poisoning can occur with as few as three berries.
Taxus baccata, yew
Most incidents with yew relate to animals though it was eaten, in the 1980s, by four prisoners as a means of suicide. Three of the four succeeded.
The interactive CD-ROM produced by St Thomas' and Kew Gardens cites a number of case reports all involving ingestion of leaves or bark. In one case it is noted that a nineteen month old child accidentally ingested some plant material. Intact seeds were found in his stools confirming that these are not digested. The child recovered.
Farmers have reported cases of poisoning in cattle when dead yew clippings have been dumped on grazing land. The assumption is that someone clipped a yew hedge in the garden, left the clippings to wither thinking that would render them safe before 'recycling' them by dumping them on farmland.
A visitor to the Alnwick Garden Poison Garden talked about his elderly neighbour who, being no longer able to manage it himself, had a group of young people in to tidy up his garden. They trimmed his yews and threw the clippings over the fence into the field at the bottom of the garden where three heifers died after eating the cuttings.
Folklore and Facts
Some years ago, it was found that the taxol found in yew could be used to produce chemotherapy treatments for breast and other cancers. The drug produced in this way is called paclitaxel. (Until someone was kind enough to correct me, I was one of the many people who thought tamoxifen was produced from yew. It is not. Tamoxifen is a synthetic drug.) For some time, large gardens made a point of keeping their yew prunings and passing these to companies to extract the taxol and produce these drugs. This was an expensive process and produced only limited amounts of the drug. Since then, however, it has been discovered that taxol is produced from a fungus that lives in the yew. Other fungi have also been found that are able to be used to produce paclitaxel. With some, artificially brewing is possible and, once that process is scaled up, it should reduce the cost and increase the availability of breast cancer treatments.
Though toxic to most animals, deer do graze on yew and gardeners are advised to avoid growing yew if there is a possibility of deer getting into the garden because it is a favourite food. That said, the list of plants which deer will browse is a very long one and there are reports of poisoning incidents so it may be large amounts are toxic to deer.
The idea that yew was grown in churchyards for making longbows is a myth. Bows were made, primarily, from the trunk of the tree so the tree was destroyed. In addition, yew grown in Britain is too brittle so the famous English longbow was made from wood imported from Europe.
The roots of the yew are very fine and will grow through the eyes of the dead to prevent them seeing their way back to the world of the living.
Sources - Galen
Galen was a Greek who worked as a doctor in Rome. He lived from about 130AD to about 215AD. He spent much time dissecting animals to try and understand the workings of the body and was the first to conclude that the kidneys are where urine is formed rather than the bladder. He also discovered the heart valves and found that the arteries carry blood around the body and not air as was thought. Many of his other discoveries were, however, erroneous and he fell out of favour during the Renaissance.
That we know so much of Galen’s writings is due to their translation into Arabic, during the 9th century, by Hunayn ibn Ishaq. Many of the English herbals refer to Galen to support their descriptions of the efficacy of plant remedies.
Yew is very long-lived and, in many cases, the yew tree in the churchyard predates the church so, the church was built round a yew tree because the pagan belief about the roots was so deep-seated.
Its longevity leads to its featuring in tales of reincarnation. If two yews are intertwined it is believed that they grew after yew stakes were driven into the chests of lovers whose relationship appalled their community.
Many place names have their origins in particular trees. York is a corruption of an Anglo-Saxon word meaning ‘the place where yew grows’.
John Gerard quotes Galen and others as saying that the yew is
very venomous taken internally and that sleeping under a Yew can
cause sickness and oftentimes death. He then dismisses these
stories by saying that ‘when I was young and went to school, divers
of my school fellows and likewise myself did eat our fills of the
berries of this tree and hath not only slept under the shadow
thereof, but among the branches also, without hurt at all, and that
not one time, but many times’.
Thomas Johnson resolves the difference of opinion between the foreign ancient sources and Gerard by asserting that the yew in England is not poisonous but, in other countries, it is highly venomous.