766 
Journal of Agricultural Research 
VoL XXVIII, No. 8 
Summary of Physical Conditions 
Pickleweed indicates land with a lighter texture than that of the desert-sage, 
with a high-water table that comes to the surface in early spring and furnishes 
an abundant siipply throughout the year, and an excessive salt content rarely 
less than 1 per cent in the first foot and averaging 13^ per cent for all 4 feet of soil. 
ADAPTATIONS TO PHYSICAL CONDITIONS 
Pickleweed is limited to soils where the water table reaches the surface of the 
soil for at least a part of the year. The soil surface is typically encrusted with salt. 
It has a relatively deep root system and is able to thrive in a water-saturated, 
strongly saline soil (PI. 10, A). It can endure-more water and more salt than 
seepweed. 
MESQUITE AND CHAMISO COMMUNITY 
TOPOGRAPHICAL RELATIONS 
This type of vegetation covers the sand hills of the region. In Coachella 
Valley (fig. 2) the greater part of this area lies in the upper part of the valley, 
below the creosote bush and breaking in on what would otherwise be occupied 
by desert-sage. At Myoma the area extends practically across the valley. 
The hills themselves vary a great deal in size and form, from the low mounds 
representing the old dunes covered with vegetation to the barest hills formed 
by the newly drifted sand. They are formed by the light soil picked up by the 
winds blowing down San Gorgonio Pass and deposited some distance farther 
down the valley. 
In the Gila Valley (fig. 3) a modification of this association is of minor im¬ 
portance. It covers low sandy knolls and ridges scattered in the valley just 
southwest of Chandler, and is in the midst of the desert-sage association. 
BOTANICAL COMPOSITION 
There are several important woody plants in this area as well as a large number 
of annuals. The chamiso ( Atriplex canescens (Pursh) Nutt.) is the most im¬ 
portant woody species in this type of vegetation where the slope is not so steep. 
The mesquite ( Prosopis glandulosa Torr.) covers the tops of the sandhills and, 
sometimes, all of the lower and older ones. On some of the oldest hills creosote 
bush is the most important shrub. Isocoma veneta acradenia (Greene) H. M. 
Hall is important in places and Parosela emoryi (A. Gray) Heller quite frequent. 
The areas of depression between the hills where silt has been washed in is occupied 
by desert-sage ( Atriplex polycarpa (Torr.) S. Wats.) 
The number of species of annuals is large, comparing favorably with the creo¬ 
sote bush land. They do not cover the ground as completely as on creosote 
bush land, but on the contrary are often widely spaced, no single species predomi¬ 
nating. The plants found in this area are given in the following list: 
PERENNIAL SPECIES OF THE MESQUITE AND CHAMISO 
Common or Frequent 
Prosopis glandulosa Torr. Psathyrotes ramosissima (Torr.) A. 
Atriplex canescens (Pursh) Nutt. Gray. 
Covillea glutinosa (Engelm.) Rydb. Atriplex polycarpa (Torr.) S. Wats. 
Isocoma veneta acradenia (Greene) H. Parosela emoryi (A. Gray) Heller. 
M. Hall. Geraea eriocephala (A. Gray) Blake. 
Abronia villosa S. Wats. 
