34 University of California Publications in Zoology. (Vou. 
Populus species (?). 
In Fish ereek cation, from 7200 to 8000 feet altitude, there 
are many cottonwoods which looked to me decidedly different 
from P. trichocarpa of lower altitudes. The leaves were very 
much larger and fewer in number, and there was a far greater 
amount of balsam in the winter buds, so that the unfolding leaves 
were extremely sticky with it. The air in the vicinity was 
strongly charged with the characteristic odor, far more so than 
with trichocarpa. The trunk was larger in proportion to the 
height of the tree, smooth barked, and mostly green. I am ad- 
vised by botanists that this is probably but a ‘‘variety’’ of tricho- 
carpa. If it were a bird or mammal we should call it a sub- 
species, due, as the characters of the cottonwood evidently show, 
to difference in temperature, rate of evaporation, ete. I saw 
similar trees at 8000 feet altitude on the upper South Fork, and 
at 7600 feet east of Bluff lake. 
Populus angustifolia James. 
Small groves of the narrow-leaved cottonwood occurred along 
the valley bottom of the upper Santa Ana, from 6100 feet (one- 
half mile or so below the mouth of the South Fork), up nearly 
to Big Meadows, 6600 feet altitude. They were mostly small- 
sized trees, the largest measured being thirty-five feet in height. 
I regret very much to say that although I tried each of the three 
summers, I failed altogether in finding any signs of fruiting. 
Populus tremuloides Michaux. 
Several groves of the slender aspens of striking appearance 
grew on the west side of the upper Fish creek canon, north of 
San Gorgonio peak, at altitudes of 7000 to 7600 feet. This was 
the only point in the whole region where I saw the species; nor 
have I ever seen aspens anywhere else in the mountains of south- 
ern California. (See pl. 13a.) 
Salix lasiolepis Bentham. 
The arroyo willow was an abundant species along all streams 
from the southern foothills to the head of the Santa Ana, 6800 
feet altitude. 
