Pinus 107 a 



5. Var. arizonica, Shaw, Pines of Mexico, 24 (1909). 



/V««. «..^.«,V«, Engelmann, in Rothrock, ^./. Geol. Surveys, vi. .60 (1878); Sargent, Silva 

 N. Amer. xi. 75, t. 559 (1897), and Trees N. Amer. 14 (1905). 



A tree 80 to 100 ft. high, with black and deeply furrowed bark. Youn^ 

 branchlets glaucous. Leaves usually in fives, but occasionally also in threes 

 according to Shaw. Cones ovoid, small, 2 to 2^ in. long. 



This occurs on the sides of canons of the mountain ranges of southern Arizona at 

 6000 to 8000 ft. elevation, sometimes forming nearly pure forests. It is more 

 abundant and attains its largest size on the sierras of northern Mexico, in Sonora, 

 Chihuahua, and Nuevo Leon. 



6. Var. macrophylla, Shaw, Pines of Mexico, 24 (1909). 



Pinus macrophylla, Engelmann, in Wislizenus, Tour N. Mexico, 103 (1848), and in Trans. St 



Louis Acad. iv. 181 (1880). 

 Pinus Engelmanni, Carribre, in Rev. Hort. 227 (1854). 



A tree 70 to 80 ft. high. Leaves 12 to 16 in. long, stout, in threes, fours, and 

 fives. Cones large (according to Engelmann, 4^ in. long) ; scales with apophysis pro- 

 longed into a reflexed protuberance, armed with either a stout or slender prickle. 



Discovered by Wislizenus on the mountains of Cosiquirachi, where it is said to 

 be abundant. According to Shaw, it occurs in Sonora and Chihuahua in northern 

 Mexico. M H 'i 



Distribution and History 



This splendid tree is the most important species of pine in western North 

 America, being the most widely distributed, the largest except P. Lambertiana, and 

 the most variable. It occurs over a vast region, extending eastwards to Montana, 

 the Black Hills of Dakota, Nebraska, Colorado, and western Texas, and westwards 

 to the shores of the Pacific, attaining its most northerly limit in the dry interior of 

 British Columbia,^ in the north Thompson valley, and around Shushwap lake, in 

 lat. 51^°, descending the Eraser river to thirty miles above Yale. It reaches south- 

 wards to Lower California, Arizona, New Mexico, and northern Mexico. It is 

 essentially a tree of dry regions and sunny aspects, yet able to endure a great degree 

 of cold in winter. It is the first pine which the traveller sees on going west across 

 the prairies in western Nebraska," and forms the greater part of the forests, now 

 rapidly disappearing, which cover the Black Hills of Dakota, • where it attains a 

 maximum height of 100 ft. and a diameter of 19 in. 



In Montana it becomes a larger tree, attaining a height of 150 ft. on the dry 

 slopes of the mountains near Helena, where it ascends to 6000 ft., in company with 

 the Douglas fir and Western larch. In the Flathead valley it grows in scattered 

 groups on the margin of the prairie in the plain of Kalispell, and gradually advances 



' Macoun, Cat. Canad. Plants, i. 466. Palmer, in ^rtV. Columbia Bull. No. 21, p. 10 (1905), gives its habitat as the 

 dry plateau between the Coast and Gold Ranges, where it is largely used for lumber. The seeds were formerly eaten by the 

 natives. 



^ Bessey, in Bot. Gazette, xxii. 245 (1896), gives its distribution in Nebraska, as along the northern border in the valley 

 of the Niobrara river, in the south-western corner, along the river Platte, where I saw it in 1904, and in patches in the centre 

 of the state in canons of the Loup. 



V L 



