THUYA 221 



1. T. gigantea, Nutt. 

 Red Cedar. Canoe Cedar. Western White Cedar 



Transverse. Growth rings usually broad. Summer wood prominent and 

 upwards of 14 tracheids thick, the transition to the spring wood 

 gradual. Spring wood open, the thin-walled tracheids squarish- 

 hexagonal, rather uniform, in regular rows. Resin cells usually in a 

 single narrow band in the summer wood of distant growth rings, thus 

 often apparently wanting. Medullary rays somewhat resinous, i cell 

 wide, distant 2-20 tracheids. 



Radial. Rays devoid of tracheids, somewhat resinous. Ray cells con- 

 spicuously contracted at the ends ; the upper and lower walls thick- 

 ish and entire or remotely pitted ; the terminal walls thin, generally 

 curved, not pitted or locally thickened ; the lateral walls with small, 

 oval pits with a lenticular or oval orifice, 1-4, or in the marginal 

 cells and low rays 6 per tracheid. Bordered pits round, in one row, 

 sometimes in pairs. Pits on the tangential walls of the summer wood 

 small, conspicuous, often remote, not confined to the outermost wall. 

 Resin cells about 15 /j. wide, 60-255 /x long, very variable, thin-walled. 



Tangential. Rays medium, narrow, the cells oblong. 



A light, soft, and rather brittle wood which is very durable in the soil. 



Relative specific gravity 0.3796 



Approximate relative fuel value 37-9 



Coefficient of elasticity in kilograms on millimeters . . 1034. 



Ultimate transverse strength in kilograms 319. 



Ultimate resistance to longitudinal crushing in kilograms 7197. 



Resistance to indentation to 1.27 mm. in kilograms . . 1114. 

 (Sargent) 



Alaska, southward through the coast ranges of British Columbia, where 

 it attains to an altitude upwards of 6000 feet, often attaining a height 

 of 150 feet and a diameter of more than 10 feet (Macoun); thence 

 through Washington, Oregon, and California, as far as Mendocino 

 County, and eastward through Washington and Idaho to northern 

 Montana (Sargent). 



2. * T. occidentalis, Linn. 

 White Cedar. Arbor Vita 



Transverse. Growth rings chiefly broad but variable. Summer wood very 

 thin, of 2-6 or upwards of 14 tracheids, the structure very open, the 

 tracheids large and squarish-hexagonal, in regular rows, rather uni- 

 form, thin-walled. Resin cells few and widely scattering, often appar- 

 ently wanting, or sometimes distantly zonate in the spring wood. 

 Medullary rays not prominent, i cell wide, distant 2-15 tracheids. 



Radial. Rays devoid of tracheids, sparingly, if at all, resinous. Ray cells 

 more or less contracted at the ends; the upper and lower walls 

 medium, with conspicuous though often distant pits ; the terminal 

 walls thin, often strongly curved, not pitted or locally thickened; 



