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Thuja
Thuja standishii foliage and cones
Scientific classification
Kingdom: Plantae Division: Pinophyta Class: Pinopsida Order: Pinales Family: Cupressaceae Genus: Thuja L.
Species
Thuja koraiensis Thuja occidentalis Thuja plicata Thuja standishii Thuja sutchuenensis

Thuja (pronounced "thoo-ya" or "thoo-ja") is a genus of coniferous trees in the Cupressaceae (cypress family). There are five species in the genus, two native to North America and three from Eastern Asia. They are commonly known as arborvitae (from Latin for tree of life), and some are colloquially known as cedars.

The thuja can grow 3-5 feet (1-1.5meters) per year and can obtain heights of nearly 50 feet (15 meters). Amongst its many uses is the ability to create a natural privacy fence in a very short time.

The leaves of Thuja are evergreen and scale-like, except young seedlings, where they are needle-like. The scales are arranged in four rows along the twigs. Thuja species are used as food plants by the larvae of some Lepidoptera species including Autumnal Moth, The Engrailed and Juniper Pug.

The male cones are small, inconspicuous, and are located at the tips of the twigs. The female cones start out similarly inconspicuous, but grow to about 1-2 cm long with 6-12 overlapping, thin, leathery scales.

The wood of thujas is light, soft and aromatic. It can be easily split and resists decay. The wood has been used for many applications from making chests that repel moths to shingles. Thuja poles are also often used to make fence posts and rails. The wood of Thuja plicata is commonly used for guitar soundboards.

The foliage of thujas is rich in Vitamin C, and was used by Native Americans and early European explorers as a cure for scurvy.

Oil of thuja is often quoted as an herbal remedy to be used topically to aid in the treatment of HPV, genital or common warts. However, clinical evidence for this action is lacking.
Thuja is a popular homeopathic remedy used to treat a variety of psychological and physiological conditions.

• Thuja koraiensis - Korean Thuja
• Thuja occidentalis - Eastern Arborvitae, Northern Whitecedar
• Thuja plicata - Western Redcedar
• Thuja standishii - Japanese Thuja
• Thuja sutchuenensis - Sichuan Thuja

A hybrid between T. standishi and T. plicata has been named as the cultivar Thuja 'Green Giant'.

Another very distinct and only distantly related species, formerly treated as Thuja orientalis, is now treated in a genus of its own, as Platycladus orientalis. The closest relatives of Thuja are Thujopsis dolabrata, distinct in its thicker foliage and stouter cones, and Tetraclinis articulata, distinct in its quadrangular foliage (not flattened) and cones with four thick, woody scales.

• Gymnosperm Database - Thuja
• Arboretum de Villardebelle - Photos of cones