236 ANATOMY OF THE GYMNOSPERMS 



7. C. arizonica, Greene 

 Cypress 



Transverse. Growth rings medium, rather uniform. Summer wood very 

 thin, upwards of 6 tracheids, and passing very gradually into the 

 spring wood. The very broad spring wood somewhat open, the very 

 variable tracheids chiefly squarish-hexagonal, the walls not thin. 

 Resin cells numerous and prominent, narrowly zonate in both the 

 spring and summer woods, sometimes in groups of larger and thicker- 

 walled cells, showing a tendency to the formation of resin canals. 

 Medullary rays rather prominent, somewhat resinous, rather numerous 

 and broad, i cell wide, distant 2-10 tracheids. 



Radial. Rays devoid of tracheids and sparingly resinous, the cells con- 

 spicuously contracted at the ends, equal to about 6-9 spring tracheids ; 

 the terminal walls chiefly straight, sparingly and locally thickened ; the 

 upper and lower walls medium to thick, not obviously pitted ; the lat- 

 eral walls with round or oval pits 1-2, or in the marginal cells 4, per 

 tracheid. Bordered pits round or elliptical, rather numerous, in i row. 

 Pits on the tangential walls of the summer tracheids rather numer- 

 ous and large, open. Resin cells not numerous, 15-20 yu, wide, 120- 

 250 /along, chiefly about 200 p.; sometimes in multiple series of much 

 broader, very variable, often isodiametric and thick-walled cells, show- 

 ing a strong tendency to the formation of resin canals. 



Tangential. Rays medium, the cells broad, more or less resinous, trans- 

 'versely oval, or in the low rays vertically oval. 



Wood soft, light, and coarse grained. 



Relative specific gravity 0.4843 



(Sargent) 



San Francisco Mountains of New Mexico and Arizona, where the tree 

 forms extensive forests on the northern slopes of the mountains at eleva- 

 tions of 5000-8000 feet ; Santa Catalina and Santa Rita mountains of 

 Arizona ; on the Sierra Madre and Guadeloupe Island, Mexico (Sargent). 



8. C. Macnabiana, A. Murr. 

 Cypress 



Transverse. Growth rings medium, uniform. Summer wood very thin, of 

 about 3-5 tracheids, open, the transition to the spring wood gradual. 

 The broad spring wood rather open, the tracheids conspicuously hex- 

 agonal, rather uniform, the walls medium. Resin cells prominent, not 

 numerous, widely scattering throughout the growth ring. Medullary 

 rays prominent, somewhat resinous, i cell wide, distant i-io, rarely 

 14, tracheids. 



Radial. Rays wholly devoid of tracheids, more or less resinous throughout, 

 individual cells often strongly so. The cells somewhat contracted at 

 the ends, equal to 4-5 spring tracheids ; the upper and lower walls 

 medium, unequal, entire, or sparingly pitted ; the terminal walls thin and 



