426 C. S. Sargent—The Forests of Central Nevada. 
farther south in New Mexico and Arizona. In the Rocky Mt. 
with twenty-eight species. In all the United States east of 
the Mississippi River there are but ten woody Rosaceous genera, 
all represented in our three Regions with the exception of the 
Southern Chrysobalanus and Neviusia. 
e comparison of these three Regions with reference to the 
distribution of the oaks will show how dependent these are on 
moisture. Oaks abound in both the Atlantic and Pacific for- 
ests, while in the Rocky Mt. Region there is but a single, ex- 
ceedingly polymorphous species, which does not reach the Ne- 
vada Region, where no oak is known; nor has this genus, so 
far as I know, any foot-hold on the dry eastern slope of the 
Sierra Nevada. A few insignificant species extend, however, 
along the mountains of Arizona and New Mexico, where the 
precipitation of moisture is more regularly distributed than far- 
ther north, and serve to connect the oaks of the Pacific with 
those of the Atlantic forests, 
been seen. 
Pseudotsuga Douglasii, which also abounds in the Rocky Mt. 
Region, and on the higher mountains of New Mexico and Ari- 
zona, does not enter the Nevada Region. This is less remark- 
able, perhaps, than the absence of Pinus ponderosa, as this tree 
does not appear, in any numbers at least, on the eastern were 
of the Sierras, and only reaches its noblest development in t 
humid climate of the northwest coast. 
Juniperus Virginiana, the most widely distributed of North 
American trees, ranges from the Saint Lawrence River to Flor- 
ida, and from the Atlantic to the Northern Pacific. It does not, 
& however, enter the Sierra Nevada Region, and is extremely 
ea ee ee a ee ee Ne ee a ee ee ee 
