Volume 8 August lo, 191 2 



MUHLENBERGIA 



PINUS PONDEROSA AND PINUS JEFFREYI 

 By a. a. Heller 



About two years ago a student of the University of Nevada 

 who proposed to take up the study of forestry, came to me for 

 instruction in dendrology. Up to that time I had given no spe- 

 cial thought to our trees, but now this fascinating branch of bot- 

 any is one of my special studies, and a regular course in den- 

 drology is being given in the College of Agriculture. 



The Sierra Nevada mountains, lying some ten miles west 

 of Reno, are timbered, especially on the lower slopes, with what 

 is commonly known as western yellow pine. A few scattered 

 trees even find their way along the dry hills north of us. Dur- 

 ing the course of my work came the problem of naming this 

 pine. Sargent's Manual, Britton's North American Trees, and 

 Jepson's Silva of California credit this region with Pinus pon- 

 derosa and what they call the \ diX'xQiy Jej^reyi^ but none of these 

 works give any definite or precise information concerning the 

 distinguishing characters of the two forms. One gets a vague 

 impression 'Ci\2X Jeffrey i may be recognized by its larger cones. 

 Finally, this spring after consulting Sudworth's Forest Trees 

 of the Pacific Slope, issued by the Forest Service at Washing- 

 ton, I got some real information. Sudworth treats Jeffreyi 

 as a species and describes it intelligibly, a thing that is rarely 

 done when a varietal name is used. His book is the best thus 

 far issued, not only in point of information but of illustrations as 

 well. After studying his descriptions oi ponder osa diudi Jeffreyi 

 I was soon able to readily distinguish the two, and a little com- 

 parison showed that quite young trees are as clearly differenti- 

 ated as mature ones. The blue-green leaves and smooth grav 



