20 MISC. CIRCULAR 31, U. S. DEPT. OF AGRICULTURE 
cups, and vary greatly in size. The trunk is ashen gray and is of 
the white oak type. 
The California blue oak, appropriately so called because of the 
bluish tint of its foliage, is another gray-trunked tree. It occurs 
on the interior slopes of the Coast Range and the west slopes of the 
F51131 
FIGURB 15.—Valley white oak (Quercus lobata) 
Sierra, in the same dry, sunny conditions that delight the digger 
pine. These trees once covered the foothills in open stands for many 
miles from Mendocino and the mountains south of Shasta clear to 
the Tehachapi. It is the oak that named Paso Robles and that occurs 
on the Carriso Plains. For years it furnished the firewood of Stock- 
ton, Modesto, Merced, Madera, Fresno, and Tulare, but the easily 
