Yew

An 'Exmoor Ponies in Conservation' project

Yew

Yew, common name for a genus of evergreen, needle-bearing trees and shrubs, and, loosely, for other members of the family to which the yews belong. Yews are native to temperate and subtropical climates throughout the world and are widely cultivated as ornamental plants, especially as hedges; in Britain, they are common in old churchyards. The needle-shaped leaves are produced more or less in two ranks along the sides of the terminal branchlets. The leaves are dark green on the upper surface and more yellow beneath. Flowers are inconspicuous; the fruit is an attractive scarlet "berry", consisting of a seed surrounded by a juicy, cup-shaped aril. The wood is slow-growing, strong, and fine-grained, and is used in cabinetmaking and for archery bows. The branches are often twisted or gnarled; the bark is red and scaly. Principal ornamental species include the English yew and the hardier Japanese yew, both with several horticultural varieties. The ground hemlock, a native North American yew of wooded hillsides and ravines, is a straggly shrub, rarely more than about 90 cm (36 in) tall. The Pacific, or western, yew is a tall tree found in old-growth forests from California to Alaska.

The foliage and seeds of yew contain highly poisonous alkaloids that act to stop the heart of an animal so suddenly that no symptoms are seen; the animal simply drops dead. The "berries" are attractive to children and their flesh is not distasteful. The flesh of the "berries" is harmless but the seed within is very poisonous. The drug taxol, approved in 1992 for treating ovarian and other cancers, was first extracted from the bark of the Pacific yew. Because the Pacific yew is a protected species, the drug from this source was in short supply. However, a semi-synthetic form of the drug, paclitaxel, has been made from the twigs and needles of the English yew, which is a readily available renewable resource.

Scientific classification: Yews make up the genus Taxus of the family Taxaceae. The English yew is classified as Taxus baccata, the Japanese yew as Taxus cuspidata, the ground hemlock as Taxus canadensis, and the Pacific, or western, yew as Taxus brevifolia.