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UNITED STATES DEPARTMENT OF AGRICULTURE 

 BULLETIN No. 680 



Contribution from the Forest Service 

 HENRY S. GRAVES, Forester 



Washington, D. C. 



PROFESSIONAL PAPER 



August 14, 1918 



MISCELLANEOUS CONIFERS OF THE 

 ROCKY MOUNTAIN REGION 



By 



GEORGE B. SUDWORTH, Dendrologist 



CONTENTS 



Page 



Scope of Bulletin 1 



Generic Characteristics of Larches 2 



Tamarack, Larix laricina (Du Roi) Koch 3 



Western Larch, Larix occidentalis Nuttall 5 



Alpine Larch, Larix lyallii Parlatore 8 



Generic Characteristics of Hemlocks 11 



Western Hemlock, Tsuga heterophylla (Raf.) Sargent 12 



Mountain Hemlock, Tsuga mertensiana (Bong. ) Sargent 16 



Generic Characteristics of False Hemlocks 19 



Douglas Fir, Pseudotsuga taxifolia (Poir. ) Britton 21 



Generic Characteristics of Incense Cedars , 27 



Incense Cedar, Libocedrus decurrens Torrey 28 



Generic Characteristics of Arborvitaes — "Cedars" 32 



Western Red Cedar, Thuja plicata D. Don 33 



Family Relationships of Yew Trees 39 



Generic Characteristics of Yew Trees 40 



Western Yew, Taxus brevifolia Nuttall 41 



Key to Genera and Species 44 



List of Publications 45 



WASHINGTON 

 GOVERNMENT PRINTING OFFICE 



1918 



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