Gymnospermae Coniferae Pinoideae Cupressineae. XII. 



THUYA {Thuja, incl. Biota) 5-6, trees of Cupressus-habit, with similar 

 phyllomorphs ; cones small, elongated, with scales obviously overlapping (imbricate), 

 as indicating so far an older phase of the Cupressus-type ; but with few scales and few 

 seeds per scale, and so far specialized. 



Type Thuya gigantea {= plicata) : forest-tree of Oregon and California, 200 ft., 

 to 12-15 diam. at base. Leader and laterals flexuous, the latter commonly ascending ; 

 phyllomorphs flexuous or drooping. ' White Cedar.' 



Shoot-system, phyllotaxis decussate as preceding, with D.V. specialization; 

 Laterals of 1st degree at intervals of 8-10 nodes ; of second degree at 6-4 nodes ; of 

 third degree at 4-2, and ultimate ramuli at every other node in alternate sequence. 

 Phyllomorphs of second laterals, 5 in. by %\, flexuous or horizontally displayed ; with 

 similar suppression of ramuli on lower margins and at base ; end-laterals erected : 

 leaves with narrow cyst and convex margins to flanking series. Internodal extension 

 5-8 mm. 



Staminate flowers terminate short ramuli of preceding season, towards the 

 basal region of the annual growth: small, 3 mm., of 5-6 pairs of stamens; pollen- 

 sacs 34 ; pollen, spherical, 30 ^ ; connective-flap dark-brown, conspicuous. 



Ovulate flower of 6 pairs of scales; terminals (1-2 pairs) rudimentary and 

 sterile, 3-4 pairs fertile, with 2 (3) ovules per scale : Pollination March (second week) ; 

 drop-mechanism efficient ; flowers located near tips of annual shoot system of previous 

 season, and erected. Fertile scale rapidly elongated in green cone (15 mm.); the 

 latter erected whatever the presentation of the phyllomorphs, slender, 5 mm. diam. ; 

 scales fused by interlocking papillose cells of a special crested growth of the upper 

 surface. 



Adult cone matured in same season ; scales diverge and seeds shed (Oct., Nov.), 

 gone by Dec. : seeds 4 mm., with lateral wing-extensions : cotyledons 2 ; seedling 

 with acicular juvenile leaves ; laterals assume the D.V. habit. 



T. occidentalis, Arbor Vitae, 50-60 ft., N. Amer. Eastern States (1596); of 

 similar growth: first laterals at long intervals (8 nodes); older scale-leaves with 

 prominent resin-cyst : cones of 4 fertile scales, 2 ovules per scale, -| inch long ; seeds 

 winged, 3-4 mm. 



T. orienta/is (= Biota), China, 50-60 ft. ; commonly planted as shrub in several 

 varieties ; fastigiate habit with phyllomorphs orientated in radial plane of tree ; to be 

 distinguished from fastigiate Chamaecyparis Lawsoniana ; laterals at 4-6 nodes on 

 main leaders ; phyllomorphs of short and slender (1 mm.) ramuli. Staminate flowers 

 abundant, of 3 pairs of stamens, yellow; pollen-sacs 3-5; pollen- spherical.. 30 /x,. 

 Ovulate flowers on upper margins of phyllomorphs, of 3 pairs of scales, uppermost 

 large, divergent, sterile; ovules 2-1 per scale; typically 6 in all, in characteristic 

 pattern as seen from above, varying 6 fertile scales and 10 ovules : Pollination March, 

 second week; green cone large, ovoid, 20 mm., with waxy bloom, erected; dehiscent 

 in autumn while scales are still semi-succulent, shrivelling up later ; seeds large, ovoid, 

 5-6 mm., without wing ; cone-scales with reflexed horn-like tip ; a very distinct type : 

 cf. argentea, aurea, compacta, gracilis, pendula, &c, forms. 



Note, in all phyllomorphic species Betinospora-hrms, with acicular juvenile 

 leaves retained on the frond-systems, may occur. 



Also known as ' White Cedar', an important timber-tree of California, confused 

 as Thuya gigantea (Hort.), and commonly planted, is Libocedrus decurrens, 

 a Thuya-form, 150 ft. and 7-8 diam., with broad fan-shaped phyllomorphs, 4-6 in., 

 spreading or drooping. The foliage-system is readily distinguished by the ' decur- 

 rent ' flanking scales, which run along the margins of the D.V. series throughout their 

 course. Ramification much as in preceding, and flowers very similar at ends of 

 ramuli. Staminate flowers, 6 mm. long, in great profusion (golden effect) of 6-8 pairs 

 of stamens, pollen-sacs 3-4, 1 mm., pollen 30 /x. Ovulate flower of typically 4-6 

 pairs of divergent scales, the penultimate pair alone fertile, with 2 ovules per scale ; 

 in this respect presenting the limit of symmetrical reduction of the ovulate system. 

 Cones erecting and increasing to |-i inch, of 2 main fruiting scales clapped together 

 on end-rudiments, and diverging to discharge 4 seeds, each with oblique wing- 

 extension twice as long as seed, 20 mm. over all. Cots. 2 ; seedling with acicular 

 juvenile leaves. 



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