February 15, 1915 137 
cent mountains, and is strewn with boulders, all affording a cer- 
tain amount of protection from the wind. Moreover, the rain- 
fall, although actually small, is greater near the mountains, and 
it is in this area that the run-off from them spreads out and 
sinks into the soil, so that moisture is available in larger amount 
and for a longer period than on the Sands. 
Beyond Palm Springs railway station the Sands stretch out 
in an apparently level expanse, over which low shrubs are re- 
motely scattered. These are almost exclusively of two species, 
Larrea tridentata and Parosela californica. Ail show the effects 
of the violent winds to which they are exposed. They are so 
bent by its force that the most of them lie declined or prostrate 
on the surface of the ground. Very commonly the roots are 
bared by the blowing away of the sand. This results in two 
ways. If there isa single taproot the shrub lies anchored, as by 
a rope, from its distal end still fixed in the sand; if the roots are 
several, it declines from the apex of a skeleton pyramid. The 
wind is too powerful to permit the formation of mounds, except 
to a very limited extent 
Larrea, when entirely prostrate, becomes closely compact 
in its manner of growth, which is normally open ard loose. A 
like compact growth is seen elsewhere in the desert in dwarfed 
but erect Larreas isolated in exposed situations. Those which 
grow from the summit of a cluster of bared roots exhibit an 
opposite effect, being less leafy than normal shrubs. ‘This is 
always the case with Parosela, which does not become abso- 
Iutely prostrate. Often from the upper surfaces of the stems of 
the shrubs the bark is cut away and the upper face of the wo d 
by the attrition of the sand blasts. 
But three perennial herbs grow here. One is Paspalum 
Urvilleanum, a coarse grass, common in drifting sands through- 
out the Californian deserts, and the only sand-binding grass they 
produce. Another is a variety of Euphorbia polycarpa, grow- 
ing in small tufts of erect stems, an inch or two long, a form 
very different from the prostrate radiate mats characteristic of 
this species and of its numerous allies which inhabit the desert. 
Both of these piants, while making their growth and accom- 
