9io 
Journal of Agricultural Research voi. xxvti, no. 12 
Few species are found in addition to the two type species, Sarcobatus 
and Atriplex confertifolia , and the half shrubs, Atriplex nuttallii, 
Kochia vestita , Dondia torreyana and in the transition zones Allenrolfea, 
Other shrubs are extremely rare, and those included here are given 
because of the interest which attaches to determinations based on species 
which are out of their natural range. 
Herbaceous species are practically limited to annuals which complete 
their growth early in the season. 
Table IX contains the constants for the individual species of the 
greasewood-shadscale association. 
GRASS-FLAT COMMUNITIES 
The grass flats, which occupy the lowest areas of the region under con¬ 
sideration with the possible exception of the salt flats, are abundantly 
supplied with moisture. This is in part supplied by springs and seepage, 
which vary greatly in salinity. The investigations of our predecessors 
in this field indicate that “the soils are characterized by (1) a high mois¬ 
ture-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 great diversity in conditions may be illustrated by determinations 
on the spring water in two different localities. Determinations on the 
water from the springs at the northern end of the Stansbury Mountains, 
and from the drainage channels from these springs, are given below (p. 913). 
These may be compared with one sample taken from a small slough in 
the lower part of the valley between Grantsville and Garfield which gave, 
on July 27, A = o.o7, P = o.84, K = .ooi7, KA = .o25i, Cl -- 0.3. 
Kearney and his associates point out (24) that while the vegetation 
of the grass flats is for the most part distinctly halophytic, there are 
limited areas around springs where the vegetation resembles that of the 
ordinary nonsaline meadow. The vegetation shows considerable diver¬ 
sity, and several subdivisions may ultimately be recognized. A precise 
classification of the vegetation must, therefore, await further investiga¬ 
tion. The transition between the grass-flat communities and the grease¬ 
wood-shadscale association and the salt-flat communities is not sharp. 
Our series of determinations for the grass-flat species is inadequate. 
This is in part due to the fact that the grass land near Grantsville has 
been intensively grazed and mowed, and in part to the fact that it is 
extremely difficult to obtain samples of some of the grasses. The leaves 
of Distichlis spicata are often covered with salt, and to remove this with¬ 
out influencing the concentration of the leaf-tissue fluids is very difficult. 
The determinations given must, therefore, be considered as prelim¬ 
inary notes on some of the species rather than as an adequate treatment 
of the vegetation. Unless otherwise stated, the determinations are based 
on collections near the southern shores of the Great Salt Lake. 
Table X gives the constants for species other than the grasses. Be¬ 
cause of the difficulty of working with the latter, it has been necessary 
to include determinations made in places other than Tooele Valley. 
