Thuja koraiensis
Thuja occidentalis
Thuja plicata
Thuja standishii
Thuja sutchuenensis

Thuja (pronounced Thuya) 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 also known as arborvitae (tree of life), due to the evergreen foliage and the many traditional medicinal uses made of these trees. Many people know thujas by the common, but incorrect name cedars.

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. The leaves are sometimes eaten by the larva of the Juniper Pug moth

The male cones are small and 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.

Species of Thuja

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

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.

External links

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