390 
Journal of Agricultural Research 
Vol. I, No. s 
and islands occupied by this plant are easily distinguishable from sur¬ 
rounding areas of sagebrush vegetation (PI. XLIII, fig. 2). The contrast 
is especially striking in spring and early summer when the sagebrush has 
a silvery green color, which is quite distinct from the dull gray of the 
Kochia. 
When viewed closely (PI. XLVI), the plants are found to be sep¬ 
arated by patches of bare ground which vary in size as the physical 
conditions are more or less favorable. In a more distant view the light 
ashy color of the soil occupied by this association blends with the color 
of the plants themselves, and this tends to create the impression 
that the plant cover¬ 
ing is dense. In 
fenced areas occupied 
by this association the 
color is modified to a 
yellowish or brownish 
gray during a few 
weeks in the early 
part of the summer, 
owing to the abun¬ 
dant fruiting heads of 
a small grass, Poa 
sandbergii (PI. XLVI, 
fig. 3). But most of 
this land is grazed by 
sheep, which soon ex¬ 
tirpate the grass or at 
least prevent its flow- 
Fig. 6 .—A representative io-meter quadrat of the Kochia association, erfilg, while leaving 
showing the location of each tuft of Kochia ( K ) and of each matlike Kochia practicallv 
colony of Poa sandbergii ( P ). * * 
undisturbed. The 
distribution of the plants of Kochia and of Poa in a typical, unmodified 
quadrat of this association is shown in figure 6. 
Physical Conditions Indicated 
The type of land occupied by the Kochia association in its typical form 
is uniform and well defined. The soil is remarkably homogeneous to a 
depth of several feet, fine in texture, and close in structure. Unlike sage¬ 
brush and shadscale lands, there is usually little gravel present. The 
smooth, polished condition of the surface after it has been wet indicates 
that this soil puddles readily. The conditions for the penetration of 
water are, therefore, unfavorable, and the run-off is doubtless high. 
