THUJA. 235 



THUIA.* 



Linnaeus, Sp. Plant. II. 1002 (1753, Thuja). Eudlicher, Synops. Conif. 50 (1847). 

 Parlatore, D. C. Prodr. XVI. 456 (1868, Thuya). R. Brown of Campster in Trans. Bot. 

 Soc. Edinb. IX. 358 (1871). Bentham and Hooker, Gen. Plant. III. 426 (1881, Thuya in 

 part). Masters in Journ. Linn. Soc. XXX. 19 (1893). Eichler in Engler and Prantl, Nat. 

 Pfl. Fain. 97 (1887, Thuja). Including Biota, Endlicher, Synops. Conif. 46; and Thujopsis, 

 Siebold and Zuccarini, Fl. Jap. II. 32. 



The Thuias with one exception, T. (jiyantea, are medium-sized or low 

 evergreen trees of narrowly conical outline ; or dense globose, fastigiate 

 or dwarf shrubs that have deviated under cultivation from the ordinary 

 habit of the species. As here understood, the genus includes five 

 species inhabiting a belt in the north temperate zone extending with 

 interruptions through North America and Asia between the 30th and 

 oOth parallels of north latitude. 

 The essential characters are : 



Flowers monoecious. Staminate flowers terminal on lateral branchlets 

 of the previous year. Stamens usually six, in decussate pairs, the 

 anthers with a sub-orbicular connective bearing two four cells. 



Strobiles maturing in one season, solitary at the end of short 

 branchlets, pendulous (except in Thuia orientalis), composed of eight 

 twelve imbricated scales in decussate pairs of Avhich the one or two 

 larger pairs only are fertile, eacli bearing two five seeds at the 

 base. 



In their vegetation, the following characters are common to all the 

 Thuias : 



Branches short and much ramified; 'branchlets flattened, usually in 

 one plane ; foliage dimorphic. 



Leaves persistent ; on adult plants, adnate to or concrescent with their 

 axial growths, scale-like, ovate or obovate oblong, or some modification 

 of that form, in four ranks in decussate pairs. 



Two of the Asiatic species do not quite conform to the American 

 type, Thuia occidentalis, in the structure of their fruits and in some 

 other minor particulars, and they have, in consequence, received 

 separate generic rank under the names of Biota (Endlicher) and 

 Thujopsis (Siebold and Zuccarini). The characters relied on to separate 

 them from Thuia proper are scarcely of sufficient value to justify their 

 retention as separate genera ; their divergence from the type is, 

 however, too significant to be neglected, and the characters which were 

 used to distinguish them as genera afford data for sectional divisions ; 



* The name Thuja was adopted by Linnneus from Tournefort's Thuya which by general 

 consent is formed from Qvx or Qv'ia (Theophrastus) the name of a tree or shrub that 

 cannot be identified but is supposed to be the North African Cypress, Call-tins quadrivalvis 

 \.) = Tetraclinis articulate (Mast.). As the earliest authoritative nomenclature reconised 



in this work is the Species Plantarum of Linnaeus published in 1753, the medieval 



orthography of Tournetort, resuscitated by L. C. Richard and afterwards by Parlatore, 



and accepted by many recent authors is here inadmissible, but following Endlicher the 

 Linnwan Thuja in its classical form Thuia is adopted. 



