The arborvitae is a particular type of coniferous evergreen tree within the cypress family, classified as genus Thuja. They come in various sizes, but are generally identifiable by their soft, scale-like leaves, flattened branches and shredding bark. Arborvitae generally prefer full sun and moist soil, and tend to grow taller in the northern U.S. than in the South. They are valued as landscaping features, and are often planted close together and pruned as hedges. There are only a few distinct species of arborvitae, two of which are native to the U.S. .
American Arborvitae (Thuja occidentalis)
One of the two Arborvitae species native to the U.S., this tree can grow 40 to 60 feet tall in the wild, but typically grows smaller in landscape settings. It assumes a narrow pyramid-like shape, often forming multiple trunks. Its foliage is dark or light green, depending on the cultivar. American Arborvitae is a slow-growing, long-lived species, sometimes lasting 800 years or more. This species is also commonly called Eastern Arborvitae or Northern Whitecedar (although it is not a cedar at all).
Giant Arborvitae (Thuja plicata)
Also commonly called Western Redcedar, this is the other arborvitae species that is native to the U.S. . Occurring naturally through the Pacific Northwest states, this tree usually reaches heights of about 70 feet in landscapes, but has been known to grow to around 200 feet tall in the wild. It is a fast-growing species, usually producing a columnar or pyramidal shape, and can tolerate some shade and drought, although it prefers moist soils and is often found growing naturally along river banks. This species can live as long as 1,400 years.
Japanese Thuja (Thuja standishii)
Native to the mountains of Japan, this arborvitae typically grows in a broad pyramidal shape, reaching heights of nearly 60 feet, and produces a reddish brown bark and dark green foliage. In Japanese tradition, this species was at one time protected as one of five "sacred species." In the U.S., it is primarily used today as an ornamental tree.
Green Giant Arborvitae (Thuja standishii x plicata)
This arborvitae is a cultivated hybrid produced from a Japanese Thuja and a Western Redcedar, and is a sturdy, disease-resistant, low-maintenance tree that is favored in landscaping. It thrives in a variety of soils and climates, grows in a broad pyramidal shape, and yields an attractive, deep green foliage. Green Giant is a quick-growing tree, and like the pure Japanese Thuja, reaches about 60 feet in height when mature.