February 28, 1907 31 
Senecio occidentalis, Festuca ovina svpina, F. Kingwt, Poa lon- 
gipedunculata, Trisetum subspicatum molle, Sitanion brevifol- 
tum, Polemonium Montrosensts, Gilia pungens, Phlox conden- 
sata, Gila montana, Pentstemon Davidsonit, Castilleja incon- 
spicua, Eriogonum rhodanthum, E. rosensis, Phlox dejecta, 
Erigeron, un. sp., Ribes Churchit, Draba Lemmoni, D. denstfolia, 
Arabs depauperata, Chrysothamnus monocephala. 
The summit of this mountain is subject to winds of great 
velocity at all seasons of the year. During snowstorms the 
- wind nearly always blows so that for a distance of about 200 
feet little or no snow is allowed to remain except in the crevices 
of the rocks. In summer these winds tend to exaggerate the 
xerophytic conditions, and the plants which survive must there- 
fore be armed with a greatly reduced leaf surface, a well devel- 
oped root system, a dense pubescence, and abundant secretions 
from the glands. As will be shown by referring back to the 
table of temperatures taken on Mount Rose, there is usually a 
great variation between night and day. ‘The writer has seen 
plants on the summit of the mountain which, when in flower, 
have been subjected to a temperature of zero, the next day lift 
up their heads and continue to bloom for several weeks. It 
seems probable then that the above mentioned characters must 
_be produced just as much against cold, as against excessive 
transpiration and heat. 
An interesting problem, not yet wholly worked out, is the 
conditions of the mountain on the south side. Approaching 
from the northeast, through the regions already referred to, and 
arriving at the summit, we look down a precipice fully exposed 
to the sun’s rays. Itextends down almost perpendicularly from 
10800 feet to the creek below, which is at 8000 feet. Clinging 
to the steep sides we find junipers within fifty feet of the sum- 
mit. The writer is inclined to believe that even at this high 
altitude it represents a small portion of the Upper Sonoran belt, 
which has become isolated. It is our intention to make a de- 
tailed study of the mountain from all sides as soon as the oppor- 
tunity presents itself. 
