arborvitae [Lat.,=tree of life], aromatic evergreen tree of the genus Thuja of the family Cupressaceae (cypress family), with scalelike leaves borne on flattened branchlets of a fanlike appearance and with very small cones. Some of the numerous cultivated varieties are dwarf forms. There are several species, two native to North America, the remainder native to Asia but sometimes cultivated in the United States. T. occidentalis, of E North America, called arborvitae, white cedar, or Northern white cedar, has many garden forms and is popular for hedges. The leaves were once used as a remedy for rheumatism, and their oil as a vermifuge. T. plicata of W North America, called giant arborvitae, red cedar, or Western red cedar, is much larger and considerably more important as lumber; it is primarily used for making shingles and shakes. The wood of both of these species is soft but quite resistant to decay, hence its popularity for fence posts. Arborvitaes are classified in the division Pinophyta, class Pinopsida, order Coniferales.

(Latin: “tree of life”) Any of six species (genus Thuja) of resinous, evergreen ornamental and timber conifers of the cypress family, native to North America and eastern Asia. Arborvitae trees or shrubs have thin, scaling outer bark and fibrous inner bark; horizontal or ascending branches; and flattened, spraylike branchlets with scalelike leaves. The Oriental, or Chinese, arborvitae (T. orientalis), a popular ornamental native to Asia, is a gracefully symmetrical shrub. Arborvitae wood is soft and lightweight but very durable, fragrant, and easily worked. The giant arborvitae (T. plicata) is the most important timber-producing species, but the wood of the American arborvitae (T. occidentalis) is also frequently used. False arborvitae (Thujopsis dolabrata) is closely related.

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