1888. | BOTANICAL GAZETTE. 261 
Purshia tridentata. ‘‘ The mountains are, in a large meas- 
ure, as destitute of trees as the valleys, or even more naked, 
from the dwarfed character of the shrubs upon the exposed 
ridges and summits.” 
n the higher ranges a sparse supply of Pinus mono- 
phylla, the nut pine, with two or three species of Juniperus, 
or red cedars, is to be found. The mountain mahogany, 
Cercocarpus ledifolis, is of frequent occurrence on high ranges 
at an altitude of 6,000 or 8,oca0 feet. 
Mr. Watson gives a list of the peculiarly desert species of 
the northern portion of the basin, amounting to 305, of which 
about one-third are strictly confined to the basin, quite a 
large number of which are southern and have extended up 
from the desert portions of Arizona and southeastern Cali- 
fornia. Going southward, the desert district by the trend of 
the Sierras is deflected eastward, and in the southern part or 
Nevada the Rio Virgin and its branches are reached, where 
the drainage of the country is to the Colorado River. A little 
further south, the Mohave River, coming in from the west, 
ents in various mountain ranges, some of which ne? 
10,000 to 11,5co feet altitude, furnishing above 6,000 feet 
Into extensive plateaus. Over a large portion of the state 
Yam He says: ‘* Crossing a series 0 
€vation of 6,000 to 7,000 feet, we begin t 
parched, SLR valley of the Gila River. A complete 
wee co : 
vitality were the expression of the plant li 
Mogollon mesa, in ihe valley of the Gila, hardness of texture 
