1006 The Trees of Great Britain and Ireland 



C. Leaf-sheaths partly deciduous, their inner part persisting as a rosette 



OF REFLEXED SCALES AROUND THE BASE OF THE LEAF-BUNDLE. LEAVES 

 ENTIRE IN MARGIN. 



* Leaves in fives. 

 4. Balfourian^e, Engelmann. Fox-tail Pines. 



Cones sub-terminal, short-stalked, ' cylindrical ; scales each with a dorsal 

 umbo, armed with a slender prickle. Seeds with long wings, easily separable. 



16. Pinus Balfouriana, Balfour. California. See p. 1054. 



Branchlets stout, pubescent. Buds ovoid, acuminate. Leaves \\ in. long, 

 without stomata on the outer surface, rigid, curved. 



17. Pinus aristata, Engelmann. Colorado, Utah, Nevada, Arizona, South- 



eastern California. See p. 1055. 

 Differs from the preceding species in the numerous resinous exudations on 

 the leaves, and in the cones and seeds. 



* * Leaves solitary or in twos, threes, or fours. 

 5. Cembroides, Engelmann. Nut Pines. 



Cones sub-terminal, sub-sessile, globose ; scales few, much thickened, 

 each with a dorsal umbo, unarmed or with a minute prickle. Seed large, 

 edible, with wing reduced to a narrow rim, remaining on the scale. 



18. Pinus monophylla, Torrey. Utah, Nevada, Arizona, California, Lower 



California. See p. 1056. 

 Leaves solitary, rigid, terete, sharp-pointed, \\ in. long, remotely placed on 

 the branchlets. 



19. Pinus edulis, Engelmann. Wyoming, Colorado, Utah, New Mexico, Texas, 



Arizona, Northern Mexico. See p. 1058. 

 Leaves in twos, rarely in threes, rigid, sharp-pointed, f to i\ in. long, 

 remotely placed on the branchlets. 



20. Pinus cembroides, Zuccarini. Arizona, Lower California, Northern Mexico. 



See p. 1059. 

 Leaves in threes, rarely in twos, softer and more slender than in the other 

 species of the section, and densely crowded on the branchlets. 



21. Pinus Parryana, Engelmann. Southern California, Lower California. See 



p. 1060. 

 Leaves in fours, rarely in fives, \\ in. long, rigid, sharp-pointed, remotely 

 placed on the branchlets. 



II. Diploxylon, Koehne, Deutsche Dendrologie, 30 (1893). Hard Pines. 



Leaves with a divided fibro-vascular bundle. Bases of the scale-leaves sub- 

 tending the leaf-clusters, decurrent on the branchlets. Cones sometimes 

 asymmetrical, and often remaining closed for several years after ripening ; scales 

 always with dorsal umbos. Seed-wing present, occasionally reduced to a narrow 

 rim ; always readily detachable from the seed. Walls of tracheids of the 

 medullary rays of the wood net- dentate. The wood is usually heavy, coarse- 



