An ornamental evergreen, the yew is a very slow-growing and long-lived tree. The trunks of some English specimens are more than 10 feet (3 meters) in diameter and are estimated to be over 1,200 years old. The wood of the yew is highly valued for cabinetmaking because of its hardness and close grain.
Yews belong to the genus Taxus of the yew family (Taxaceae). The genus consists of about eight species of small trees or shrubs found throughout the Northern Hemisphere. The English yew (T. baccata) is cultivated in North America as far north as New York. The trunk is short and thick, with bark that has deep fissures when the tree becomes old. It may reach 60 feet (18 meters) in height. The Pacific, or western, yew (T. brevifolia) grows from 15 to 45 feet (about 4.5 to 14 meters) high. It is found throughout much of the United States from sea level to 8,000 feet (2,400 meters); at the timberline it is a dwarf shrub.
Chinese and Japanese yews grow to 50 feet (15 meters), but in North America they are commonly cultivated as small, ornamental trees. The ground hemlock (T. canadensis) is a low, straggling shrub found in the United States and Canada.
All yews have a naked seed surrounded by a fleshy scarlet cup which looks like an open berry. Small, solitary flowers appear in the spring. The leaves are flat, 1/2 to 1 3/4 inches (1.3 to 4 centimeters) long, and pale on the underside. Narrow and sharply pointed, they are arranged spirally around the twig.
The foliage and seeds of the yew are highly poisonous. Yew poisoning results in gastroenteritis and heart and respiratory failure and can be fatal to both humans and animals. In many temperate countries veterinary surgeons consider yews to be the most dangerous of all native trees. However, the bark of the Pacific yew and some other species contains the alkaloid taxol, which has proved effective in the treatment of some types of cancer.