Thuja

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Thuja

 

(in Russian, biota), a genus of monoecious arboreous plants of the family Cupressaceae, represented by one species, Thuja orientalis (Biota orientalis).

The tree attains a height of 8–10 m, but it is more often found as a shrub. The needles on the mature branches are scale-like, in a decussate pattern. The crown is ovate and consists of many flat shoots (“scales”) situated in the vertical plane. The erect-standing cones, when immature, are blue-green, and later are dry and mostly reddish brown. The seeds mature in the second year. Thuja is native to China and Korea. In the southern regions of the USSR it is grown as a decorative plant. Thuja is drought resistant and easily pruned.

REFERENCE

Derev’ia i kustarniki SSSR, vol. 1. Moscow-Leningrad, 1949.

A. P. SHIMANIUK


Thuja

 

(arborvitae), a genus of coniferous evergreen trees or shrubs of the family Cupressaceae. The shoots are flattened, and the scalelike or, in juvenile forms, needlelike leaves are appressed to the stem. The cones are borne on the ends of the branches and consist of three or four pairs of leathery-woody scales. The upper scales are sterile. The seeds, which have two narrow wings, mature in the fall of the first year.

There are five species, distributed in North America and East Asia. The plants do not require special growing conditions; for example, they can tolerate urban industrial pollution. They are used as greenery. The American arborvitae (T. occidentalis), a low tree with a pyramidal or ovate crown, is cultivated in orchards and parks throughout Europe (weeping, dwarf, and variegated-leaf forms). In the USSR the species is grown in the steppe and forest zones as far as Archangel’sk, in Siberia, and in the Far East. Its soft, durable wood is used in its native land—eastern North America—for railroad ties, posts, furniture, and lathed items. The leaves yield an essential oil used in medicine and perfume.

The giant arborvitae (T. plicata) grows in northwestern North America. It is 45–55 m tall and has a conical crown and horizontal branches. The durable wood is highly valued for finish work, for lathe work, and for the production of fences, posts, and similar items. The giant arborvitae is cultivated as an ornamental. In the USSR it is grown in gardens and parks of the European portion, the Black Sea Shore of the Caucasus, and Middle Asia (with irrigation). Other species are less commonly cultivated.

REFERENCE

Derev’ia i kustarniki SSSR, vol. 1. Moscow-Leningrad, 1949.

V. N. GLADKOVA

thuya, western red cedar, Pacific red cedar

A soft, lightweight, straight coarse-grained wood that is relatively weak; the sap-wood is white, the heartwood is reddish; because of its durability it is widely used for shingles, tanks, and other exterior applications.