62 



GENUS PINUS 



XI. AUSTRALES 



Pits of the ray-cells small. Leaf-hypoderm biform or variable. Spring-shoots uninodal in some, 

 multinodal in other species. Cones dehiscent at maturity. 



This group combines the dehiscent cone of the Lariciones with the wood-anatomy of the seroti- 

 nous Pines. Also the multinodal spring-shoot first appears here and is gradually developed among 

 the species, absent in Nos. 37-39, sometimes present in Nos. 40-43, and prevalent in Nos. 44-47. 



All the species are of the Western Hemisphere, and among them may be found the biform hypo- 

 derm of the leaf, the internal resin-duct, and the total absence of external resin-ducts, characters 

 common in American Hard Pines. The eastern species are quite constant in their characters and 

 present no varietal forms ; the western species, on the other hand, are very variable. This difference 

 may be due to the even level and slight climatic differences of the Atlantic states and to the remark- 

 able diversity of altitude and climate of the western states and Mexico. 



Outer walls of the leaf-endoderm thick. 



Cones large, attaining 12 cm. or more in length. 

 Prickles of the cone inconspicuous. 



Bark-formation late 37. 



Bark-formation early 38. 



Prickle of the cone conspicuous 39. 



Cones small, 7 cm. or less in length 40. 



Outer walls of the leaf-endoderm thin. 

 Spring-shoots mostly uninodal. 



Prickle of the cone slender, sometimes deciduous. 



Cones mostly oblique 41. 



Cones symmetrical 42. 



Prickles of the cone stout and persistent 43. 



Spring-shoots multinodal. 



Resin-ducts internal 44. 



Resin-ducts mostly medial. 



Prickle of the cone stout 45. 



Prickle of the cone slender. 



Bark-formation late 46. 



Bark-formation early. . 47. 



pseudostrobus 

 Montezumae 

 ponderosa 

 teocote 



Lawsonii 



occidentalis 



palustris 



caribaea 



taeda 



glabra 

 echinata 



37. PINUS PSEUDOSTROBUS 



1839 P. PSEUDOSTROBUS Liudlcy in Bot. Reg. xxv. Misc. 63. 



1839 P. APULCENSis Lindley in Bot. Reg. xxv. Misc. 63. 



1842 P. TENUiFOLiA Bentham, PI. Hartw. 92. 



1846 P. ORiZABAE Gordon in Jour. Hort. Soc. Lond. i. 237, f . 



Spring-shoots uninodal, conspicuously pruinose. Bark-formation late, the cortex of young trees 

 smooth. Leaves in fascicles of 5, sometimes of 6, from 15 to 30 cm. long, drooping; resin-ducts 

 medial, hypoderm variable in amount, often in very large masses, the outer walls of the endoderm 

 thick. Conelets mucronate. Cones from 7 to 14 cm. long, ovate or ovate-conic, symmetrical or 

 oblique, deciduous and often leaving a few basal scales on the trees; apophyses rufous or fulvous 

 brown, flat, elevated or, in one variety, prolonged in various degrees, the prolongations nearly uni- 

 form or much more prominent on the posterior face of the cone, the mucro usually deciduous. 



A species of the subtropical and warm-temperate altitudes of Mexico and Central America. Its 

 range includes both eastern and western slopes of the northern plateau. Its northern limit is in 

 Nuevo Leon, and it probably reaches in Nicaragua the southern limit of pines in the Western 

 Hemisphere. It is distinguished from all its associates by the smooth gray trunk of the young trees, 

 by their long internodes, and by their drooping gray-green foliage. 



