THE NATIVE VEGETATION AND CROPS OF THE 
COLORADO DELTA IN THE SALTON BASIN. 
(Supplement to Bulletin No. 140.) 
By Joseph Burtt Davy. 
The following general observations were made on a hasty trip into 
the Colorado Desert between March 25 and April 2 of this j^ear: 
The region covers such a vast area that it was impossible to do any¬ 
thing in the way of a detailed study of its vegetation in a few days, as 
almost the whole time was occupied in travelling from point to point. 
The flora is a limited one, very monotonous in character, tracts 
many miles in extent being covered by an almost uniform vegeta¬ 
tion, of but few species and varying slightly in individual composi¬ 
tion over large areas, according to the physical or chemical nature 
of the soil. On this account the native vegetation affords an excellent 
guide to the general condition of the land. 
PHYSICAL CONDITION OF THE SOIL. 
Although there is a very marked difference between the vegetation 
of the sandy mesa and old beach lands and that of the alluvial plain, 
the texture of the soil on the plain itself has practically no effect on 
the vegetation. The same plants are found alike on the heavy 
”Imperial Clay” and on the Dune Sand, as well as on all the inter¬ 
mediate soils, with but few and unimportant exceptions. This fact is, 
however, of minor practical importance in determining the nature of 
the soil, because the texture of the surface soil is so clearly evident 
from its appearance to the sight and touch. 
The relative humidity of the soil is much more clearly indicated, 
however. When the water-table is within about twenty feet of the 
surface, Arrowweed {Pinched sericea) grows luxuriantly, forming 
dense groves six to ten feet high. 
Wherever salt-springs occur, a dense growth of Salt-grass (Dis- 
tichlis spicata) is found, and it is usually accompanied by luxuriant 
growths of Mesquit {Prosopis juliflora) , Arrowweed (Plucked sericea ), 
and the Washington palm (Washingtonia filifera) , although the latter 
is found nowhere on the plain, (except under cultivation) but only 
above the old beach line. The Mesqnit is evidently dependent, in 
this region, upon the proximity of the ground-water, or upon period¬ 
ical flooding. Although it is an exceedingly hardy tree, capable of 
withstanding adverse conditions inimical to the growth of the few 
other trees found in the region, it frequently happens that on areas 
