74 TREES OP NORTH AMERICA 



very durable in contact with the soil, light reddish brown, with thin nearly white sap- 

 wood; often injured by dry rot but largely used for fencing, laths and shingles, the 

 interior finish of buildings, for furniture, and in the construction of flumes. 



Distribution. Singly or in small groves from the basin of the Santiam River, Ore- 

 gon, southward along the Cascade Mountains and the western slopes of the Sierra 

 Nevada, and on the California coast ranges from Mendocino County to the mountains 

 of southern California and Lower California; most abundant and of its largest size 

 on the sierras of central California at elevations of 5000-7000 above the sea. 



Often cultivated as an ornamental tree in western and central Europe, where it 

 grows rapidly and promises to attain to a large size; hardy and occasionally planted 

 in the middle Atlantic states. 



10. THUYA, L. Arbor-vitae. 



Resinous aromatic trees, with thin scaly bark, soft durable straight-grained heart- 

 wood, thin nearly white sapwood, slender spreading or erect branches, pyramidal 

 heads, flattened lateral pendulous branchlets disposed in .one horizontal plane, form- 

 ing a flat frond-like spray and often finally deciduous, and naked buds. Leaves 

 decussate, scale-like, acute, stomatiferous on the back, on leading shoots appressed 

 or spreading, rounded or slightly keeled on the back, narrowed into long slender 

 points; on lateral branchlets much compressed in the lateral ranks, prominently 

 keeled and nearly covering those of the other ranks; on seedling plants linear- 

 lanceolate, acuminate, spreading or reflexed. Flowers minute, monoecious, from 

 buds formed the previous autumn, terminal solitary, the two sexes usually on dif- 

 ferent branchlets ; stamiuate ovoid, with 4-6 decussate filaments, enlarged into sub- 

 orbicular peltate connectives bearing on their inner face 2-4 subglobose anther-cells; 

 pistillate oblong, with 8-12 oblong acute scales opposite in pairs, the ovuliferous 

 scales at their base bearing usually 2 erect bottle-shaped ovules. Fruit an ovoid- 

 oblong erect pale cinnamon-brown cone maturing in one season, its scales thin, 

 leathery, oblong, acute, marked near the apex by the thickened free border of the 

 enlarged flower-scales, those of the 2 or 3 middle ranks largest and fertile. Seeds 

 usually 2, erect on the base of the scale, ovate, acute, compressed, light chestnut- 

 brown ; seed-coat membranaceous, usually produced into broad lateral wings distinct 

 at the apex; cotyledons 2, longer than the superior radicle. 



Thuya is confined to northeastern and northwestern America, to Japan and 

 northern China. Four species are recognized. Of the exotic species the Chinese 

 Thuya orientalis, L., with many varieties produced by cultivation, is frequently planted 

 in the United States, especially in the south, for the decoration of gardens, and is 

 distinguished from the Japanese and American species by the thick umbonate scales 

 of the cone, only the 4 lower scales being fertile, and by the thick rounded dark red- 

 purple seeds without wings. 



Thuya is the classical name of some coniferous trees. 



* 



CONSPECTUS OF THE NORTH AMERICAN SPECIES. 



Fruit with usually 4 fertile scales. 1. T. occidentalis (A). 



Fruit with usually 6 fertile scales. 2. T. plicata (B, F, G). 



1. Thuya occidentalis, L. White Cedar. Arbor-vitae. 



Leaves on leading shoots often nearly \' long, long-pointed and usually conspicu- 

 ously glandular, on lateral branchlets much flattened, rounded and apiculate at the 



