Yew — symbol of death and life

Yew is any tree or shrub of the genus Taxus; the English yew is Taxus baccata, a tree with a dual personality. This evergreen can live for millennia.

Characteristically it continues to grow by rooting its branches and forming a grove around itself.

The yew is capable of apparent death and resurrection; there are many reports of old, haggard and injured yews that suddenly sprout again and put on new growth.

Sitting inside a hollow yew you feel the weight of centuries. The oldest wooden artifact known is a yew spear, found near Clacton, more than 250,000 years old. What better representation than the yew of rebirth and eternal life!

On the other hand the yew has a strong association with death. It is the graveyard tree and we may find its deep-dark green almost eerie and its shady presence morbid and oppressive.

All parts of the yew, except for the fleshy red seed cups, contain the highly poisonous alkaloid taxine, which causes death due to cardiac arrest and respiratory failure. Yew stimulates spasms of the womb and it has been used as an abortifacient.

Famously the wood was used for making English long-bows, fearsomely powerful weapons that inflicted terrible damage on the enemy at Crécy (1346), Poitiers (1356) and Agincourt (1415). Taxus may be related to the Greek toxicon, the poison with which arrow-heads were dressed to make them absolutely lethal.

Yew was used for making tools of death, but latterly it has provided the basis of hope of increased life expectancy for some cancer patients.

Paclitaxel, the mitotic inhibitor present in yew bark, was found in highest concentration in the Pacific yew (T brevifolia). The immense problem was that the bark of six trees was needed to gather enough paclitaxel to treat one patient.

A French group recognised the problem of yield and found that relatively large quantities of 10-deacetylbaccatin, the first step in a semisynthetic route to taxol, could be isolated from needles of T baccata, a more renewable source than the endangered Pacific yew.

The initial motivation for semisynthetic approaches to paclitaxel led to the development of the closely related taxane chemotherapy agent docetaxel.

Currently paclitaxel is produced using plant cell fermentation technology; it may also be produced by fungal culture.