PINE TREES OF ROCKY MOUNTAIN REGION. 23 



than in the case of other conifers in its general range. Single-leaf 

 pine occurs commonly in coarse, gravelly soils, shallow deposits over- 

 lying granite, limestone, or shale and often in the crevices of rocks. 

 It frequently forms pure, open stands over large areas, but usually 

 it is associated with other trees, such as mountain mahogany, Utah 

 juniper, mountain red cedar, oaks, tree yuccas, and occasionally with 

 pinon. The largest trees and the pure stands occur mainly at the 

 lower and middle levels of the tree's vertical range. 



Pinus monophylla is very intolerant of shade throughout life. 

 Seedlings grow faster, however, for several years under partial or 

 light shade and also when protected from hot winds. 



This species bears some seed nearly every year and abundantly at 

 intervals of two or three years. As in the case of other nut pines, the 

 wingless seeds fall near the tree, whence they are sometimes dissemi- 

 nated by flood waters. Birds and squirrels eat large quantities of 

 them and Indians and whites collect them extensively for food. 

 Exposed loose soil is the best seed bed, though even here germination 

 occurs sparingly, so that reproduction is very scattered. 



LONGEVITY. 



Pinus monophylla is an exceedingly slow growing tree, reaching 

 an age of from 100 to 225 years. Trees in thin, dry soil are espe- 

 cially slow in their growth, specimens from 4 to 6 inches in diameter 

 being from 80 to 100 years old. Trees occurring in deeper soils grow 

 more rapidly, those from 10 to 12 inches in diameter being from 150 

 to 160 years old. Further records are required to establish its extreme 

 age limit. 



BRISTLE-CONE PINE. 



Pinus arisiata Engelmann. . 



COMMON NAME AND EAKLY HISTORY. 



Bristle-cone pine is known to people in and near its high mountain 

 habitat chiefly as " fox-tail pine," because of the close resemblance of 

 its foliage to that of the true fox-tail pine (Pinus balfouriana) , a 

 California species. It is sometimes known also as "hickory pine." 

 An appropriate and distinctive name is bristle-cone pine, which is 

 derived from the tree's specific name, aristata (bearded) , referring to 

 the bristlelike prickles of the cone scales. 



It is probable that the earliest discovery of this pine was made 

 in 1853 by Capt. J. W. Gunnison, of the U. S. Army, who collected 

 a coneless branch in Cochetopa Pass (nearly southwest of Pikes 

 Peak), Colorado, which Dr. Engelmann 1 believed to be of this 



1 Trans. St. Louis Acad. Sci., II, 205. 1863. 



