UNITED STATES DEPARTMENT OF AGRICULTURE 
I BULLETIN No. 327 
Contribution from the Forest Service 
HENRY S. GRAVES, Forester 
Washington, D. C. 
PROFESSIONAL PAPER 
February 19, 1916 
THE SPRUCE AND BALSAM FIR TREES OF THE 
. ROCKY MOUNTAIN REGION. 
By George B. Sudworth, 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 
Page. 
Generic characteristics of balsam firs- 
Continued. 
Alpine fir Abies lasiocarpa (Hook.) NuttalL. 24 
Cork fir A bies arizonica Merriam 27 
Grand fir — "White fir" Abies grandis Lind- 
ley 29 
White &r Abies 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 
