406 
Journal of Agricultural Research 
Vol. I, No. 5 
ANNUAL AND BIENNIAL SPECIES 
Hordeum jubatum L. 
Salicornia rubra A. Nels. 
Suaeda erecta (Wats.) A. Nels. 
A triplex spatiosa A. Nels. 
Cleome serrulata Pursh 
Melilotus alba Desv. 
Erythraea arizonica (Gray) Rydb. 
Orthocarpus tolmiei H. and A. 
Carduus scariosus (Nutt.) Heller 
Physical Conditions Indicated 
Reference to Tables XIV and XV shows that there is much variation in 
the moisture and salinity conditions of the grass-flat area, but, broadly 
speaking, the soils are characterized by (i) a high moisture-holding 
capacity, ascribable partly to the fine texture and partly to the large 
quantity of organic matter present, (2) the presence near the surface 
and usually throughout the summer of moisture available for growth 
(above the wilting coefficient), and (3) a salt content sufficiently high 
to be injurious to many crop plants. The soils under the salt-grass 
community (Table XV), while usually much more saline than under the 
Sporobolus-Chrysothamnus community (Table XIV), have an average 
salinity inferior to that of the salt flats (Tables XVI and XVII). 
Sporobolus-Chrysothamnus Community 
The Sporobolus-Chrysothamnus community (PI. XTVIII, fig. 3) covers 
a large part of the grass-flat area in Tooele Valley. In places one or the 
other of the dominant species occurs where the other is absent, but they 
are more often closely associated. Salt grass ( Distichlis spicata) is also 
usually more or less abundant in this community. 
Tussock grass ( Sporobolus airoides) forms coarse mats, which are as 
a rule closely grazed by animals. In late summer the feathery purple 
panicles of this grass are a characteristic feature of the vegetation of 
the grass flats in such areas as are not grazed. The rabbit brush 
(Chrysothamnus graveolens glabrata) is a much-branched shrub, from 2 
to 4 feet high, with whiplike slender branches having green bark 
and very small, narrow leaves. Its color is bright green, modified in 
late summer by the numerous small heads of yellow flowers which 
resemble those of goldenrod. The physical conditions where this com¬ 
munity occurs are indicated by the data given in Table XIV. 
