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'''''Thuja''''' ({{pron-en|ˈθuːdʒə}} or {{IPA-en|ˈθjuːdʒə|}})<ref>''Sunset Western Garden Book,'' 1995:606–607<br>{{OED|Thuja}}</ref> is a genus of [[conifer]]ous [[tree]]s in the [[Cupressaceae]] (cypress family). There are five species in the genus, two native to [[North America]] and three native to eastern [[Asia]].<ref name=farjon>Farjon, A. (2005). ''Monograph of Cupressaceae and Sciadopitys''. Royal Botanic Gardens, Kew. ISBN 1-84246-068-4</ref><ref name=gd>Gymnosperm Database: [http://www.conifers.org/cu/th/index.htm ''Thuja'']</ref> The genus is [[Monophyly|monophyletic]] and sister to ''[[Thujopsis]]''. They are commonly known as '''arborvitae''' (from [[Latin]] for ''tree of life'') or '''thujas'''; several species are widely known as ''cedar'' but because they are not true [[Cedrus|cedars]] (''Cedrus'') it has been recommended to call them redcedars or whitecedars.<ref name=kelsey>Kelsey, H. P., & Dayton, W. A. (1942). ''Standardized Plant Names'', second edition. American Joint Committee on Horticultural Nomenclature. Horace McFarland Company, Harrisburg, Pa.</ref> They are [[evergreen]] [[tree]]s growing from {{convert|10|to|60|ft|m|abbr=none}} 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 [[conifer cone|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 [[seed]]s with a pair of narrow lateral wings.<ref name=farjon/> The five species in the genus ''Thuja'' are small to large evergreen trees with flattened branchlets. The leaves are arranged in flattened fan shaped groupings with resin-glands, and oppositely grouped in 4 ranks. The mature leaves are different from younger leaves, with those on larger branchlets having sharp, erect, free apices. The leaves on flattened lateral branchlets are crowded into appressed groups and scale-like and the lateral pairs are keeled. With the exception of ''T. plicata'', the lateral leaves are shorter than the facial leaves (Li ''et al'' 2005). The solitary flowers are produced terminally. Pollen cones with 2-6 pairs of 2-4 pollen sacked sporophylls. Seed cones ellipsoid, typically 9-14mm long, they mature and open the first year. The thin woody cone scales number from 4-6 pairs and are persistent and overlapping, with an oblong shape, they are also basifixed. The central 2-3 pairs of cone scales are fertile. The seed cones produce 1 to 3 seeds per scale, the seeds are lenticular in shape and equally 2 winged. Seedlings produce 2 cotyledons.<ref>Flora of North America Editorial Committee. 1993. ''Pteridophytes and gymnosperms. Flora of North America north of Mexico, v. 2''. New York: Oxford University Press. ISBN 0-19-508242-7 Page 410.</ref><ref>Henry A Gleason. ''New Britton and Brown Illustrated flora of Eastern North America and adjacent Canada Vol 1, The Pteridophya, Gymnospermae and Monocotyledoneae.'' Hafner Press, pp 58-67. </ref> A [[Hybrid (biology)|hybrid]] between ''T. standishi'' and ''T. plicata'' has been named as the [[cultivar]] ''Thuja'' 'Green Giant'. {{Inc| Thuja (Thya or Thyia, an ancient Greek name for a resinous tree or shrub). Also spelled Thuya or Thuia. Including Biota. Pinaceae. Arbor-vitae. Ornamental woody plants, grown for their handsome evergreen foliage and formal habit. Resiniferous trees with short horizontal much ramified branches; the flattened branchlets arranged frond-like: lvs. decussate, scale-like, appressed, usually glandular on the back: fls. monoecious, globose, small, terminal on short branchlets, staminate yellow and consisting of usually 6 opposite stamens each with 2-4 anther-cells; pistillate consisting of 8-12 scales in opposite pairs, of which only the middle ones, or in the section Biota the lower ones, are fertile, each scale with 2 ovules inside at the base: strobiles globose-ovate to oval-oblong, with 2 seeds under the fertile scales.— Five species occur in N. Amer., E. and Cent. Asia. The wood is light and soft, brittle and rather coarse-grained, durable in the soil; it is much used for construction, cabinet-making, and in cooperage. T. occidentalis contains a volatile oil, and thujin and is sometimes used medicinally. The thujas are trees of narrow pyramidal habit, but low and bushy in many of the numerous garden forms, with much ramified branches, the branchlets arranged frond-like, flattened and clothed with small scale-like leaves; the fruit is a small strobile or cone not exceeding 1 inch in length. The well-known T. occidentalis is hardy North; and also T. Standishii, T. plicata, and several forms of T. orientalis are hardy as far north as Massachusetts. Thujas are favorites for formal gardens. They are all of regular symmetrical habit. Their numerous garden forms vary greatly in habit and in color of foliage. For planting as single specimens in parks they are mostly too stiff and formal, but they are well suited for massing on borders of streams or lakes. The most beautiful and the most rapidly growing species is T. plicata. Thujas are well adapted for hedges and windbreaks (see Gn.M.2:15). They bear pruning well and soon form a dense hedge. They thrive best in somewhat moist, loamy soil and are easily transplanted. Propagation is by seeds sown in spring. The varieties, especially those of T. occidentalis, are usually propagated by cuttings taken late in summer and kept during the winter in a cool greenhouse or frame; also by grafting on seedling stock in summer or early in spring in the greenhouse. The varieties of T. plicata and T. orientalis are usually grafted, since they do not grow readily from cuttings, except the juvenile forms of the latter, as var. decussata and var. meldensis. Consult Retinispora. T. dolobrata, Linn.-Thujopsis dolobrata. {{SCH}} }} ==Cultivation== {{edit-cult}}<!--- Type cultivation info below this line, then delete this entire line --> ===Propagation=== {{edit-prop}}<!--- Type propagation info below this line, then delete this entire line --> ===Pests and diseases=== {{edit-pests}}<!--- Type pest/disease info below this line, then delete this entire line --> ==Species== ;5 Species{{wp}} * ''[[Thuja koraiensis]]'' - Korean Thuja * ''[[Thuja occidentalis]]'' - Eastern Arborvitae, Northern Whitecedar * ''[[Thuja plicata]]'' - Western Redcedar * ''[[Thuja standishii]]'' - Japanese Thuja * ''[[Thuja sutchuenensis]]'' - Sichuan Thuja ==Gallery== {{photo-sources}}<!-- remove this line if there are already 3 or more photos in the gallery --> <gallery> Image:Upload.png| photo 1 Image:Upload.png| photo 2 Image:Upload.png| photo 3 </gallery> ==References== *[[Standard Cyclopedia of Horticulture]], by L. H. Bailey, MacMillan Co., 1963 <!--- xxxxx *Flora: The Gardener's Bible, by Sean Hogan. Global Book Publishing, 2003. ISBN 0881925381 --> <!--- xxxxx *American Horticultural Society: A-Z Encyclopedia of Garden Plants, by Christopher Brickell, Judith D. Zuk. 1996. ISBN 0789419432 --> <!--- xxxxx *Sunset National Garden Book. Sunset Books, Inc., 1997. ISBN 0376038608 --> ==External links== *{{wplink}} {{stub}} __NOTOC__
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