Thuja occidentalis first described in 1753 by Carolus Linnaeus (1707–1778), is commonly known as Arborvitae, a name which is particularly used in the horticultural trade in the United States. It is Latin for “tree of life” – due to the supposed medicinal properties of the sap, bark and twigs. Despite its common names, it does not belong to the cedar genus, nor is it related to the Australian white cedar, Melia azedarach. It is an evergreen coniferous tree, in the cypress family Cupressaceae,
Description. Eastern arborvitae is an evergreen coniferous species of tree with fan-like branches and scaly leaves. Unlike the closely related species Thuja plicata, it is only a small tree, growing to a height of 33 to 66 feet (10 – 20 m) tall with a trunk up to 1.3 feet (0.4 m) in diameter at breast height, exceptionally to 100 feet (30 m) tall with a 5 foot (1.6 m) trunk diameter; the tree is often stunted or prostrate. The bark is red-brown, furrowed and peels in narrow, longitudinal strips. The foliage forms in flat sprays with scale-like leaves 0.12–0.20 inches (3 – 5 mm) long. The seed cones are slender, yellow-green ripening brown, 0.4 to 0.6 inches (10 – 15 mm) long and 0.16 to 0.20 inches (4 – 5 mm) broad, with 6 to 8 overlapping scales. The branches may take root if the tree falls.
Distribution. This species is native to Canada — Manitoba, Ontario, Québec; Prince Edward Island, New Brunswick and Nova Scotia. In the USA — Minnesota, Michigan, Wisconsin, Illinois, Indiana, Ohio, Kentucky, Tennessee, North Carolina, Virginia, West Virginia, Maryland, Pennsylvania, New York, Connecticut, Massachusetts, Vermont, New Hampshire, Maine; growing at elevations up to 2,800 feet (0 – 900 m) above sea level on mostly calcareous substrates, neutral to basic swamps, shores of lakes and rivers, uplands, cliffs, and talus.
T. occidentalis is widely used as an ornamental tree, particularly for screens and hedges, in gardens, parks and cemeteries. Over 300 cultivars exist, showing great variation in colour, shape and size, with some of the more common ones being: ‘DeGroot’s Spire‘, ‘Ellwangeriana’, ‘Hetz Wintergreen’, ‘Lutea’, ‘Rheingold’, ‘Smaragd’ (a.k.a. ‘Emerald Green’), ‘Techny’, and ‘Wareana’. It was introduced into Europe as early as 1540.Attributed from: Wikipedia