400 
Journal of Agricultural Research 
Vol. I, No. 5 
Variations from the Typical Association 
The shadscale area in Tooele Valley comes into contact on its upper 
limit with the sagebrush and the Kochia associations and on its lower 
limit with the greasewood-shadscale association. In each case mixed 
or transitional communities result. The conditions under which shad- 
scale mingles with sagebrush and with Kochia have been discussed on 
preceding pages. The transition to the greasewood-shadscale associa¬ 
tion, which is a very gradual one, will be treated in connection with the 
latter association. 
greasewood-shadscale association 
Topographical Relations 
The area occupied by the greasewood-shadscale association forms an 
interrupted belt (see map, PI. XLII) across the valley between the areas 
occupied by the shadscale association, and by the grass flats, respectively. 
It also covers the low ridges and hummocks which alternate with the 
basinlike depressions and flats near the shore of Great Salt Lake (PI. 
XLIII, fig. i, and PI. XLVII, fig. 3). In general, it occupies all areas 
where the water table is sufficiently high to make moist soil accessible to 
the deep-rooting greasewood and where at the same time 1 or 2 feet of 
the surface soil are sufficiently dry to permit the growth of shadscales 
Where the water table is too low this association gives place to the pure 
shadscale. On the other hand, as the soil becomes wet nearer and nearer 
the surface, the shadscale gradually disappears and at the edge of the 
grass flats greasewood associates with Allenrolfea occidentalis and Suaeda 
moquinii instead of with A triplex conjertifolia. 
Botanical Composition 
This type of vegetation is dominated by two shrubby species, grease¬ 
wood (Sarcobaius vermiculatus; see fig. 10, p. 404) and shadscale (A triplex 
confertifolia; fig. 9, p. 398). In typical areas these plants intermingle in 
approximately equal numbers, but on the highest ground (PI. XLVII, 
fig. 2) shadscale is strongly predominant, while on the lowest land where 
this association occurs greasewood is the more abundant. Kochia vestita 
is abundant in much of the area occupied by this association, but the 
plants are so small in comparison with the two dominant species that 
they do not affect the general appearance of the vegetation. In spots of 
limited size greasewood and Kochia are associated, shadscale being 
absent. The soil conditions in such spots do not differ materially from 
those of the typical greasewood-shadscale association. Few other species 
are found, and of these the number of individuals is usually small. The 
following list includes all species noted as occurring in the greasewood- 
shadscale association: 
