Arbor Vitæ

Arbor Vitæ (Thuja), an evergreen genus of coniferous trees and shrubs allied to the cypress. The common Arbor Vitæ (T. occidentalis) is a native of North America, especially between lat. 45° and 49°, but has long been well known in Europe. It is a tree of 20 to 50 feet high; the young leafy twigs have a balsamic smell, and both they and the wood were formerly in great repute as a medicine; the oil obtained by distillation from the twigs, which has a pungent and camphor-like taste, has been employed as a vermifuge. The wood of the stem is reddish, soft, and very light, but compact, tough, and durable, bearing exposure to the weather remarkably well. The tree is often planted in Britain as an ornamental tree, but does not attain so great a size as in its native country. It delights in cool, moist situations.—The Chinese Arbor Vitæ (T. Biota orientalis), a native of China and Japan, which is immediately distinguishable from the former species by its upright branches and larger, almost globose and rough cones, is also a common ornament of pleasure-grounds in Britain and on the Continent; but it does not grow so tall as the preceding, and is more sensible of the cold of severe winters. The balsamic smell is very agreeable. The tree yields a resin having a pleasant odour, to which high medicinal virtues were formerly ascribed; hence the remarkable name, Arbor Vitæ ('tree of life'), given to this species, and extended to the genus. In its native country, this species also attains the size of a considerable tree.—There are several other species of Thuja, some of which seem well suited to the open air in the climate of Britain, and others require the protection of greenhouses. See CONIFERÆ; ARAUCARIA, CEDAR, CYPRESS, SANDARACH.—When the human cerebellum is cut vertically, a tree-like appearance seen is called arbor vitæ.