12 BULLETIN 460, IT. S. DEPARTMENT OF AGRICULTURE. 



In general white-bark pine is a good seeder, but seed production 

 varies greatly with the region and locality. In the North it seeds 

 only at long intervals, while in the South it bears seed frequently. 

 Reproduction is rather scanty, this doubtless being due in part to 

 the large quantities of seed eaten by birds and squirrels. Because 

 the seeds are carried to the ground in the heavy unopened cones, 

 reproduction is confined mainly to the vicinity of seed trees. Being 

 unprotected by the mother trees, seedlings that come up in exposed 

 places are often damaged by winds, which whip the stems about so 

 that they are sometimes worn in two at the collar by rubbing against 

 the rough granite soil. 



LONGEVITY. 



White-bark pine is moderately long-lived, attaining an age of 

 from 250 years (when it may be about 19 inches in diameter) to 

 325 years. Very few records of the tree's longevity are available. 



MEXICAN WHITE PINE. 



Pinus strobiformis Engelmann. 



COMMON NAME AND EARLY HISTOBY. 



This little-known species is without a distinctive common name, 

 being known only as " white pine." The name " Mexican white 

 pine " is suggested because the greater part of the tree's range is in 

 Mexico, its range in the United States being very limited (Map 

 No. 4). 



Mexican white pine was discovered in Chihuahua, Mexico, in 1846 

 by Dr. A. Wislizenus. Twenty-six years after its discovery in 

 Mexico Dr. J. T. Eothrock found it in the Santa Rita Mountains. 

 Arizona. The first description and the technical name of it were 

 published in 1848. The botanical history of Mexican white pine 

 shows that the tree was little understood until about 25 years ago. 

 In 1868 a French author referred to it as Pinus ayacahuite, which is 

 another Mexican species ; in 1878 Dr. Engelmann named a form of it 

 Pinus flexilis, y reflexa, which four years later (1882) he ranked as 

 a distinct species, Pinus reflexa. Under this name Mexican white 

 pine was chiefly known to American botanists until 1889, when Prof. 

 C. S. Sargent 1 pointed out that Engelmann's Pinus reflexa and P. 

 strobiformis refer to the same tree, the latter name being the older. 



Recently Dr. G. R. Shaw 2 reduced this species to "P. ayacahuite var. 

 brachyptera Shaw." For the present, however, the writer prefers to 



1 Gard. and For. II, 496, 1889. 2 The Pines of Mexico, PI. vl, p. 11, 1909, 



