Pinus io 47 



Leaves in fives, persistent for five or six years, densely crowded on the 

 branchlets, directed forwards, 2 to 3 in. long, stout, rigid, curved, scarcely twisted, 

 entire ' in margin, sharp-pointed, marked on the three surfaces with three or four 

 stomatic lines ; resin-canals marginal ; basal sheath \ in. long, early deciduous. 



Cones sub-terminal, erect when young, spreading in the second year, sub-sessile, 

 3 to 5, rarely 10 in. long, 2 ovoid-cylindrical; scales 3 opening and spreading hori- 

 zontally when mature, about 1 in. long and f in. wide, obovate, with the upper 

 margin reflexed ; apophysis thickened, brown, tipped with a triangular umbo. 

 Seed ovoid, compressed, 5 to ^ in. long, brownish, angled on the lateral and upper 

 margins ; wing rudimentary, about T ^ in. long, lacerated when the seed falls. 



This species is distinguished from all the cultivated five-leaved pines with a 

 completely deciduous leaf-sheath, except P. pumila, by the leaves being entire in 

 margin. The latter species, which in its continental form has also non-serrulate 

 leaves, is readily distinguishable from P. fiexilis by the shaggy reddish brown 

 tomentum on its young branchlets. 



Variety 



Shaw considers the following to be a variety of this species : 



Var. reflexa, Engelmann, in Rothrock, Rep. Geo/. Surveys, vi. 258 (1878). 



Pinus reflexa, Engelmann, in Bot. Gazette, vii. 4 (1882); Mayr, Fremdland. Wald- u. Park- 



baurne, 388 (1906). 

 Pinus strobiformis, Sudworth, U.S. Forestry Bull. No. 14, p. 17 (1897) (not Engelmann *) ; 



Sargent, Silva N. Amer. xi. 33, tt. 544, 545 (1897), and Trees N. Amer. 6 (1905). 



This differs from the type in the much reflexed, usually thin cone-scales. The 

 leaves, either entire or serrulate in margin, are with or without stomatic lines on the 

 back. It was found in northern Chihuahua in Mexico by Pringle in 1887, and seems 

 to be intermediate between P. flexilis and P. Ayacahuite, though all the cones seen 

 by Shaw resembled those of P. flexilis in size and general appearance. According 

 to Sargent, this pine attains 80 to 100 ft. in height, and is scattered singly, or in 

 small groups, on rocky ridges of the Santa Catalina, Chiracahua, and Santa Rita 

 mountains of southern Arizona, and on the Sierra Madre of Chihuahua in Mexico. 

 It has not been introduced. 



Distribution and Cultivation 



This species is widely distributed on the eastern slope of the Rocky Mountains 5 

 from Alberta to Texas, and occurs also in the mountains of northern Arizona, Utah, 



1 In rare cases the leaves are slightly serrulate, and have been distinguished as var. serrulata, Engelmann, in Rothrock, 

 Wheeler's Report, vi. 258 (1 878). 



2 Cones of abnormal length, in addition to those of the ordinary size, are produced on trees growing in the San Francisco 

 mountains of northern Arizona ; and have been distinguished as var. macrocarpa, Engelmann, in Rothrock, Wheeler's Report, vi. 

 258 (.878). 



3 Shaw, loc. cit., says : Scales straight or reflexed, and variable in thickness. 



4 P. strobiformis, Engelmann, is a variety of P. Ayacahuite. 



6 In the Rocky Mountains of Canada P. flexilis is found only on the margins of the rivers issuing from the mountains. 

 Cf. Macoun, in Trans. R. Soc. Canada, xii. 4, p. 13 (1894). 



