28 GENUS PINUS 



in an acute margin, and terminated by a salient, often acute umbo; seed wingless, the testa bare of 

 spermoderm. 



This species ranges from British Columbia through Washington and Oregon, over the mountains 

 of northern California and the Sierras as far south as Mt. Whitney, and, on the Rocky Mountains, 

 through Idaho and Montana to northern Wyoming. It is found at the timber-line of many stations 

 and forms, in exposed situations, flat table-like masses close to the ground. It is a species of no eco- 

 nomical importance and is too inaccessible for the profitable gathering of its large nuts, which are 

 devoured in quantity by squirrels and by Clark's crow, a bird of the same genus with the pinivorous 

 Nutcracker of Europe. 



P. albicaulis is distinguished from its allies by its entire leaves with both dorsal and ventral stomata, 

 from P. flexilis by its indehiscent cone, and from all of these species by its seed without membranous 

 cover or rudimentary wing. It was united with P. flexilis by Parlatore and Gordon, and, later, was re- 

 ferred to that species as a varietal form by Engelmann (in Brewer & Watson, Bot. Calif, ii. 124). 

 Parrish's P. albicaulis (in Zoe, iv. 350), extending its range to the mountains of southern California, 

 proves to be P. flexilis (Jepson, Silva Calif. 74). 

 Plate VIII. 



Fig. 90, Two cones and seed. Fig. 91, Leaf -fascicle. Fig. 92, Magnified leaf -section. 



n. FLEXILES 



Seeds wingless, the spermoderm forming a narrow border with a rudimentary prolongation. Cones 

 dehiscent at maturity. 



The dehiscent cone distinguishes this group from the Cembrae. Therefore confusion of P. koraiensis 

 with P. Armandi, or P. albicaulis with P. flexilis should be impossible. The peculiar seed is found 

 again only in the northern variety of P. ayacahuite. 



Leaves usually entire, the stomata dorsal and ventral 4. flexilis. 



Leaves serrulate, the stomata ventral only 5. Armandi. 



4. PINUS FLEXILIS 



1823 P. FLEXILIS James in Long's Exped. ii. 34. 



1882 P. REFLEXA Engelmann in Bot. Gaz. vii. 4. 



1897 P. STROBiFORMis Sargent, Silva N. Am, xi. 33, tt. 544, 545 (not Engelmann). 



Spring-shoots pubescent; branchlets very tough and pliant. Leaves from 3 to 9 cm. long, entire, 

 or serrulate in the southern variety, persistent for five or six years; stomata dorsal and ventral or, in 

 the south, sometimes ventral only; resin-ducts external. Cones from 6 to 25 cm. long, ovate or 

 subcylindrical, short-pedunculate; apophyses pale tawny yellow, or yellow ochre, lustrous, often 

 prolonged and more or less reflexed, thick, the margin together with the umbo raised above the 

 surface of the cone. 



This species grows on the Rocky Mountains from Alberta in the Dominion of Canada to Chihua- 

 hua in northern Mexico and ranges westward to the eastern slope of the Sierras and to the southern 

 mountains of California. The wood, where accessible, is manufactured into lumber. It may be seen 

 in the Arnold Arboretum and in the Royal Gardens at Kew. 



P. flexilis is recognized by its lustrous yellow cones. This and the constantly external ducts of its 

 usually entire leaves distinguish it from P. Armandi. From P. albicaulis, with similar leaves, it differs 

 by its dehiscent cone. At one extreme the cone of P. flexilis is not unlike that of P. albicaulis, at the 

 other extreme it approaches the characteristic cone of P. ayacahuite, with prolonged reflexed scales. 

 Hence the confusion of P. albicaulis with P. flexilis (Murray, Parlatore and others) and of P. flexilis 

 with Engelmann's P. strobiformis. Sargent's P. strobiformis, illustrated in the Silva of North Amer- 

 ica, is the form of this species known as var. reflexa of Engelmann. 

 Plate IX. 



Fig. 93, Two cones and seed. Fig. 94, Leaf-fascicle. Fig. 95, Magnified leaf-section. 



