UNITED STATES DEPARTMENT OF AGRICULTURE 



ULLETIN No. 



Contribution from the Forest Service. 

 HENRY S. GRAVES, Forester. 



jd&*^SL 



Washington, D. C. 



PROFESSIONAL PAPER 



May 26, 1917 



THE PINE TREES OF THE ROCKY MOUNTAIN 



REGION. 



CONTENTS. 



Page. 

 Scope of bulletin 1 



Generic characteristics of pines 2 



White pines 4 



Western, white pine (Pinus monticola 

 Douglas) 4 



Limber pine (Pinus flexilis James) 7 



White-bark pine (Pinus albicaulis Engel- 

 mann) 9 



Mexican white pine (Pinus strobiformis 

 Engelmann) 12 



Mexican pifion (Pinus eembroides Zucca- 

 rini) 15 



Pifion; nut pine (Pinus edulis Engel- 

 mann) '. . . 18 



Single-leaf pine (Pinus monophylla Tor- 

 rey and Fremont) 21 



Page. 

 Generic characteristics of pines — Contd. 



Bristle-cone pine (Pinus aristata Engel- 

 mann) .-. 23 



Yellow pines 26 



Arizona pine (Pinus arizonica Engel- 

 mann) 26 



Western yellow pine (Pinus ponderosa 



Lawson) 28 



Apache pine; "Arizona longleaf pine" 



(Pinus apacheca Lemmon) 33 



Chihuahua pine (Pinus chihuahuana 



Engelmann) 36 



Lodgepole pine (Pinus contorta Loudon). 38 



Jack pine (Pinus banksiana Lambert)... 42 



Key to species 46 



SCOPE OF THE BULLETIN. 



In this bulletin are described and figured the distinguishing char- 

 acteristics of all of the pine trees that inhabit the Rocky Mountain 

 region. Graphic illustrations of the range of these trees and dis- 

 cussions of their forest habits are also included. The exact limits 

 of the Rocky Mountain territory covered by this publication are 

 given in Bulletin No. 207 1 of the Forest Service, to which the 

 reader is referred. Other statements made there regarding the gen- 

 eral plan of treating the subject, sources of information, and acknowl- 

 edgments of assistance 2 received apply to the present bulletin. The 



1 " The Cypress and Juniper Trees of the Rocky Mountain Region, 1915. 

 2 Grateful acknowledgment is here made to Dr. H. N. Whitford for valuable notes on 

 the range of Pinus manticola and P. albicaulis in British Columbia. 

 61354° — Ball. 460—17 1 



