arborvitae

(botany) Any of the ornamental trees, sometimes called the tree of life, in the genus Thuja of the order Pinales.

A plant, sometimes called the tree of life, belonging to the genus Thuja of the order Pinales (Coniferales). It is characterized by flattened branchlets with two types of scalelike leaves. At the edges of the branchlets the leaves may be keeled or rounded; on the upper and lower surfaces they are flat, and often have resin glands. The cones, about 1/2 in. (1.25 cm) long, have the scales attached to a central axis. See also Pinales; Resin; Secretory structures (plant).

The tree is valued both for its wood and as an ornamental. Thuja occidentalis, of the eastern United States, is known as the northern white cedar. It occurs in moist or swampy soil from Nova Scotia to Manitoba and in adjacent areas of the United States, and extends south in the Appalachians to North Carolina and Tennessee. Other important species include the giant arborvitae (T. plicata); oriental arborvitae (T. orientalis); and Japanese arborvitae (T. standishii). Among the horticultural forms are the dwarf pendulous and juvenile varieties. See also Forest and forestry; Tree.