UNITED STATES DEPARTMENT OF AGRICULTURE 



m BULLETIN No. 327 mm 



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Contribution from the Forest Service 

 HENRY S. GRAVES, Forester 



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Washington, D. C. 



PROFESSIONAL PAPER 



February 19, 1916 



THE SPRUCE AND BALSAM FIR TREES OF THE 

 ROCKY MOUNTAIN REGION. 



By George B. Sud worth, Dendrologist. 



CONTENTS. 



Scope of the bulletin 1 



Generic characteristics of spruces 2 



Black spruce Picea mariana (Mill.) B., S., 



& P 3 



White spruce Picea canadensis (Mill.) B., 



S., & P 6 



Engelmann spruce Picea engelmanni Engel- 



mann 10 



Blue spruce— "Colorado blue spruce" Picea 



parryana (Andre) Gardeners' Chronicle.. 14 



Generic characteristics of balsam firs 17 



Balsam fir Abies balsamea (Linn.) Miller. . . 20 



Generic characteristics of balsam firs — 

 Continued. 



Alpine fir A bies lasiocarpa (Hook.) Nuttall. . 24 



Cork fir A bies arizonica Merriam 27 



Grand fir — "White fir" Abies grandis Lind- 



ley 29 



White fir A bies concolor ( Gord. ) Parry 33 



Shasta red fir Abies magnifica shastensis 



Lemmon 38 



Key to genera 42 



Key to Picea 42 



Key to Abies 43 



SCOPE OF THE BULLETIN. 



This bulletin deals with the distinguishing characters, geographic 

 distribution, and forest habits of all of the spruce and balsam-fir 

 trees that grow naturally within the Rocky Mountain region, which 

 roughly includes the desert and mountain territory lying between the 

 Great Plains and the eastern border of the Pacific Slope States. 

 Canadian territory lying directly north of our Rockies and Mexican 

 territory adjacent to our Southwest are included, because the ranges 

 of some of the spruces and firs extend into these regions. The method 

 of treating the subject, sources from which data on the geographic 

 range were obtained, and the origin of other information used in this 

 bulletin are fully discussed by the writer in a recently issued publica- 

 tion on the " Cypress and Juniper Trees of the Rocky Mountain Re- 

 gion." 1 Acknowledgments made there of assistance received apply 

 also in the case of the present bulletin. 



1 Bulletin No. 207, U. S. Department of Agriculture, 1915. 

 Note. — This bulletin will be of service botanically or commercially for the trees described. 

 10529°— Bull. 327—16 1 



