|Nordic Spire™ Arborvitae - Thuja 'Rebild'|
These conifer, evergreen shrubs or
small trees are popular as ornamentals
Trees or shrubs in the genus Thuja (pronounced "thoo-ya" or "thoo-ja") in the cypress family Cupressaceae are commonly known as Arborvitae, and sometimes "cedar", although they are not cedars. There are five species in the genus, two native to North America and three native to eastern Asia.
Evergreen, coniferous trees growing to 10–60 m tall, with stringy-textured reddish-brown bark. The shoots are flat, with side shoots only in a single plane. The leaves are scale-like 1–10 mm long, except young seedlings in their first year, which have needle-like leaves. The scale leaves are arranged in alternating decussate pairs in four rows along the twigs. 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 at maturity when 6–8 months old; they have 6-12 overlapping, thin, leathery scales, each scale bearing 1–2 small seeds with a pair of narrow lateral wings.
Thuja species are used as food plants by the larvae of some Lepidoptera species including Autumnal Moth, The Engrailed and Juniper Pug. The foliage is also readily eaten by deer, which where deer population density is high can adversely affect the growth of young trees.
Arborvitae wood 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.
The Genus Thuja contains five species of coniferous evergreen trees, of small to medium size, and a few shrubs, usually dense. Bark is scaly. Branches usually horizontal or also ascending, developing a conical crown. Twigs more or less flattened. Leaves opposite, scale-like, appressed, lateral leaves partly overlap facial leaves. Cones small, ovate or oblong. Native to North America or eastern Asia. Many cultivars of different size, form and color are available. The foliage of several types discolor in winter, reducing their acceptability. Some tend to thin out with age and attain an unkempt appearance. Arborvitae are especially popular in the Midwest and eastern U.S.
There is general consensus that one species, Thuja orientalis, does not belong in this genus and has been transferred to the genus Platycladus, hence Platycladus orientalis. However, most nurseries and retail outlets continue to use the older designation. (1)
1. Oregon State University Dept. of Horticulture
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Family Cupressaceae – Redwood, Cypress, Arborvitae, Juniper
There are thirty (many monotypic) genera and 142 species in the family Cupressaceae, now widely regarded as including the Taxodiaceae, previously treated as a family. The Cupressaceae are found in the fossil record as far back as the Jurassic Period, about 210 million years ago. Cupressaceae Index | Tree Encyclopedia | Trees Index