Cut down a forest. Cut all the forests down — and you destroy the spiritual life of a woodland culture. This is called genocide, the systematic destruction of a cultural group, blow by blow.

The Irish yew, Taxus baccata, the ancient tree of bereavement of the Celtic culture, was extirpated from the lush lands of Ireland by the English. The forested landscape described by the courts of the High King of Tara as being iúrach, or abounding in evergreen yew trees, was razed to the ground. The tough, close-grained, bendable, watertight wood was used to craft weapons of war and by the woman of the house, bean an tí, in her dairy.

The wood from the mature yews, when grown in rich soil, has exceptional qualities. Since the internal plumbing of tracheids are flexible and retain great strength even when bent in shape, yew wood was said to be the best for making bows, the principal weapons of ancient warfare. The Celts were known for their hand-and-eye coordination. They were the elite of the military, even in Rome.

By luck or by chance the yew returned to Ireland in 1780, still during the penal times. One spring morning near Lough Erne in what is now northern Ireland, a farmer was doing the rounds. His eye caught something strange growing in one of his fields. On closer inspection he found two small evergreen yew saplings growing stoutly side by side. His land had long been cleared of forest for the plantation English, some of them Beresfords, to take over. These two yews, almost miraculously sprung from seed that had lain dormant, were all that remained of the yew forests of ancient Ireland.

The yew, Taxus baccata, is a medicinal tree, as are the other seven species in its genus (though some botanists consider all eight species to be just one). Across the globe this renowned species is a tree of bereavement to almost all cultures, its wood used in coffins, its branches twined in funeral wreaths. The tree is poisonous, with one strange exception. The bright-red fruit, called an aril, is composed of a bony seed that sits inside the pulpy flesh. The pulpy red flesh is a choice bird food that seems to be non-toxic.

Otherwise the Irish yew and all the yews across the world are poisonous to cattle and to people. But they produce an extraordinary family of biochemicals called the taxols, which are currently used in the treatment of many cancers. Like many medicines in this arena, a small dose is a cure, while a large dose is a deadly poison.

The Druidic physicians were aware of the yew cures and placed the tree firmly in the land of the living as a bile, or sacred tree. In Celtic households, butter stored in yew containers was put on burns and scalds to exclude the air from the burnt surface until healing began. Milk stored in yew vats was boiled with onions as a medicinal drink against colds and used as a body sweat against viruses. Buttermilk from yew jugs was drunk in the spring as a tonic and also to clarify the quality of the skin of teenagers, especially those afflicted with minor eruptions, redness and scarring, and was sometimes applied around the skin of the eyes to relieve facial tension.

Many of the more valuable medicines of the Druidic physicians, using bark, root bark, aril, wood and foliage, have been lost. These secret medicines were given as part of an honour system to important families to hold into the future. They went underground for 500 years during the Penal Laws only to re-emerge in the late 1900s. Then they were thrown out as useless folk medicine in favour of modern pills. A number of these medicines were cures for cancer. Many were used in pain management, as well.

But some old cures remain. The Iroquois peoples of North America used yew extract from their species, Taxus brevifolia, as a synergist for their medicines. A synergist is a biochemical boosting mechanism that makes a medicine more effective. Yew was traditionally used as a steam bath treatment for pain. The foliage in water was taken to a boil, and the steam was then used to induce perspiration. The taxol extract landed on the skin, dried there, and relieved the chronic pain in joints. The yew was also used to reduce numbness of limbs and to reclock menstruation.

The Druids, in their wisdom, put the letter I for iúr into the Ogham script. The letter is a vertical line intersected by five horizontal, parallel lines. Iúr was their word for yew in this alphabet of trees.