24 BULLETIN 460, U. S. DEPARTMENT OF AGRICULTURE. , 



species. So keen an observer as Dr. Engelmann could hardly have 

 mistaken the foliage of any other Rocky Mountain pine for that of 

 Pinus aristata. The first authentic specimens of the tree were, how- 

 ever, collected by Dr. C. C. Parry on Pikes Peak, Colorado, in 1861 . 

 Bristle-cone pine received its present technical name, Pinus aristata, 

 in 1862, since which date the history of the tree has been practically 

 free from confusion. In 1878 it was designated as P. halfouriana 

 var. aristata Engelm., but this suggested relationship to the Califor- 

 nia species is not generally accepted. 2 



DISTINGUISHING CHARACTERISTICS. 



Bristle-cone pine varies in height and form from a half -prostrate 

 twisted shrub, at very high elevations, to a bushy-crowned tree from 

 35 to 40 feet, in the situations more favorable for growth. Ordinarily 

 it is from 15 to 30 feet high and from 12 to 18 inches in diameter, 

 the tallest trees being from 20 to 30 inches or more in diameter. The 

 trunk is clear of branches for about 6 or 8 feet. The rather wide 

 bushy crown of long, drooping lower branches and of irregularly long 

 upright top limbs is characteristic of single trees or those in open 

 stands on wind-swept slopes. In denser stands, in less exposed situa- 

 tions, the crown form is narrower. Young trees have a distinctly 

 pyramidal crown with short rather thick branches which stand out 

 from the stem at right angles. The bark of old trunks is a dull red- 

 dish brown and rather shallowly furrowed, the main flat ridges being 

 irregularly connected by narrower diagonal ones. Bark on the trunks 

 of small trees and of the large limbs of old trees is smooth and chalky 

 white. 



The deep green foliage is densely clustered at the ends of the 

 branches, the needles being closely pressed down (PL XV), in this 

 respect closely resembling the true fox-tail pine (Pinus balfourwna): 

 As a rule, the leaves are borne in clusters of 5, occasionally of 4, 

 and are about 1| to 1^ inches long (PL XV, c). The leaves of each 

 season's growth persist for approximately 12 or 14 years. 



1 Pinus aristata was first introduced into cultivation at the Harvard Botanic Garden, 

 by Dr. Asa Gray, to whom Dr. Parry sent seeds from Colorado in 1S62. Dr. Gray raised 

 a number of seedlings from this seed, and Prof. C. S. Sargent (Gard. and Forest, X, 470, 

 1897) states that some of these plants still growing in the vicinity of Boston had in 35 

 years attained heights only of from 12 to 18 inches, from which it would seem that the 

 species is not adapted to that part of our Atlantic region, and certainly not to regions 

 farther south. A trial of this pine near Portland, Me., shows decidedly better results. 

 Mr. H. A. Jackson writes that trees he raised from seed planted in 1908 are now (1917) 

 21 feet high and growing thriftily. Accounts differ as to when this pine was first intro- 

 duced into England, the date given in one instance (Gard. Chron. IV, 549, 1875) being 

 1863, and in another (Gordon, Pinetum, ed. 2, 292, 1875), 1S70. It appears to be better 

 adapted to the climate of England, where, according to Elwes and Henry (The Trees of 

 Great Britain and Ireland, V, 1055, 1910) trees have attained heights ranging from 15 

 to 25 feet during a period, probably, of 35 to 40 years. 



