36 University of California Publications in Zoology. [Vou-5 
latter neighborhood, on the north-facing slope down toward Bear 
valley, the chinquapin grew as low as 7000 feet altitude. (See 
pl 1/25) 
Quercus chrysolepis Liebman. 
The eolden oak was a conspicuous component of the flora of 
the upper part of the Upper Sonoran zone, and in places ex- 
tended up into the Transition mingling with the black oaks and 
conifers. Along all the cations of the Pacifie slope it was abun- 
dant, serubby in exposed places, and becoming a large tree in 
sheltered canons. It was almost as numerous, though looking 
somewhat different (smaller leaves, ete.), in the pinion belt on 
the desert side of the mountains. In shaded canons on the north 
side of Gold mountain and near Cactus Flat I saw large trees like 
those on the Pacific side of the mountains. 
Quercus dumosa Nuttall. 
The serub oak was an abundant species characterizing the 
Upper Sonoran zone, on both the Pacifie and desert slopes, 
though less conspicuous on the latter. It ran up on south-facing 
slopes north and east of Seven Oaks to at least 6500 feet altitude. 
It was seldom that I noted this species in close proximity to any 
pines excepting pinons. (Other less common forms of oaks were 
seen and may have represented distinct species. ) 
Quercus californica (Torrey) Cooper. 
The California black oak was a characteristic Transition zone 
species in the least arid parts of the region. If such a term be 
considered in a general sense I should say it thrived best at about 
middle Transition; at least it did not extend as high as the lower 
margin of the chinquapin beit. Black oaks were abundant inter- 
mingling with the pines over the gently sloping mesa bounded 
on the north by the upper Santa Ana and on the south by the 
abrupt high San Bernardino ridge. This belt extended from the 
head of Mountain Home ereek to beyond Fish creek, and from 
an altitude of as low as 5000 feet on north slopes up to 7500 feet. 
There was a similar belt alone the ridge south of Bear valley 
from the vicinity of Bluff lake to the north base of Sugarloaf. 
And I saw a few black oaks in some ravines on the north side of 
3ear lake, and on the north side of Gold mountain. 
