DESERT SHRUB VEGETATION. 
Figure 54.—Joshua trees and wild buckwheat. (Creosote bush.) The trees are about 25 feet high 
and present a unique appearance. The soil is loose and sandy and free from injurious amounts of alkali. 
Dry farming is seldom successful. Under irrigation the land is largely devoted to orchards. Hesperion, 
Calif. , 
Figure 55.—Giant cactus, c hoi la, visnaga,. palo verde, ocotillo, and other plants. (Creosote bush.) 
A luxuriant phase of cactus-yucca vegetation found on rough or rocky land at the upper edge of the desert 
valleys. This vegetation presents a striking appearance due to the unusual character of the dominant plants. 
The land is not usually of agricultural value, due to its rough and uneven character. Chandler, Ariz. 
Joshua tree-wild buckwheat (fig. 54).—In the Mohave 
Desert region the Joshua tree ( Glistoyucca brevifolia) 
is one of the most picturesque plants. It forms trees 
of from 15 to 30 feet in height, spaced from 15 to 100 
yards apart. Much of the ground is covered by wild 
buckwheat ( Eriogonum fasiculatum) and similar low- 
growing shrubs. Juniper often pushes down into the 
area from the forest above, and creosote bush up into 
the area from the desert below. The moisture condi¬ 
tions under this type are relatively favorable, and the 
soil is light and pervious and free from harmful 
amounts of salt. 
Gactus-palo verde (fig. 55).—The flora and appear¬ 
ance of the vegetation in central and southern Arizona 
is different from that in the Colorado and Mohave 
deserts. The vegetation in Arizona is largely palo 
verde ( Cercidium torreyanum) , cactus ( Camegiea 
gigantea , Ferocactus wislizeni , Opu/ntia fulgida , 0. 
marrdllata , O. spinosior , O. echinocarpa , and O. acan- 
thocarpa ), and ocotillo (Fouquieria splendens ), with 
the smaller and less conspicuous bur sage ( Franseria 
dumosa and F. deltoides). No portion of the 
southern desert is more varied or picturesque 
than this. The great columnar bodies of the 
giant cactus, the white, spiny, bushlike plants 
of the palo verde, the tall radiating stems of the 
ocotillo, and the annual flora following the rainy 
periods, combine to produce a vegetation of great 
variety and of unusual interest. The land is 
rough and the soil is rocky and consequently of 
little agricultural value. 
Lechuguilla-sotol (fig. 56).—In New Mexico 
and the Big Bend country of western Texas the 
yuccalike plants and scattered shrubs constitute 
the dominant vegetation. Lechuguilla (Agave 
lechuguilla) is the most characteristic plant, but 
sotol ( Dasylirion texanum) and other species 
and ocotillo {F ouquieria splendens') are also im¬ 
portant. The soil is rocky for the most part and 
of little or no agricultural yalue. The value of 
this type for grazing depends largely upon the 
various grasses from the mesquite grasslands 
which occur scattered throughout this portion of 
the desert. During periods of drought the sotol 
is chopped open and cattle subsist on the thick¬ 
ened bases of the leaves, which are relatively 
high in sugar content and are considered excep¬ 
tionally good emergency feed. 
California sagebmtsh .—This type lies below the true 
chaparral zone and is limited in distribution. It is 
found in the dry interior valleys or slopes west of the 
Coast Range of southern California and extends over 
into the desert below the chaparral on the east side of 
the range and at higher elevations across southern 
Arizona. Much of the best irrigated orchard land of 
southern California was formerly, covered with Cali¬ 
fornia sagebrush. 
California sage—encelia .—On the drier slopes west of 
the mountains in California encelia ( Encelia farinosa) 
forms dense thickets of gray broad-leaved shrubs from 
2 to 4 feet high. On the more humid slopes this plant 
is replaced by California sagebrush ( Artemisia cali- 
fci'nioa) of about the same size, but with very fine 
foliage of darker color. During the winter rainy sea¬ 
son and in early spring there are many showy flower¬ 
ing herbs. The soil is moistened during this period to 
a depth of 6 feet or more, and growth continues usually 
until about midsummer, when this stored moisture is 
exhausted. 
Wild buclcwheat. —On especially dry hills below the 
chaparral on the coast side of the mountains and above 
the creosote-bush zone on the desert side, pure stands 
of wild buckheat ( Eriogonum fasiculatum) cover large 
areas. 
Mesquite .—While mesquite is scattered throughout 
the southern desert from the Pacific coast to the Gulf 
of Mexico, it is relatively more important in the east¬ 
ern portion than in the western. In New Mexico and 
Arizona the mesquite often constitutes the principal 
type in the subirrigated valleys. In the extreme west¬ 
ern part of the Colorado Desert mesquite thickets occur 
only rarely and are relatively insignificant. 
Cat’s claw .—Extensive thickets of cat’s claw, practically im¬ 
penetrable because of the sharp, recurved spines, occur in 
Texas and portions of New Mexico. 
Mesquite-chamiso .—In southern Arizona, New Mex¬ 
ico, and California isolated sandy ridges are usually 
covered by mesquite ( Prosopis juliflora) and chamiso 
(Atriplex canescens). In the western part of the 
desert dunes are often built up around the mesquite 
trees, which become more and more submerged, only 
the tips of the branches protruding. On these new 
areas chamiso is the principal shrub. 
Mesquite-rayless goldenrod .—In portions of Arizona, New 
Mexico, and California the vegetation consists of scattered low 
shrubs of rayless goldenrod (Isocoma coronopifolia ) with small 
trees of mesquite. This type probably represents land on 
which the original shrub vegetation has been destroyed and 
replaced by rayless goldenrod. 
GREASEWOOD (SALT DESERT SHRUB). 
Within the Great Basin the drainage is often en¬ 
tirely hemmed in by mountain ranges and the salts 
leached from the soil accumulate in the lower valleys. 
This is especially true of areas which are character¬ 
ized by ground or artesian water. The water rises 
to the surface and by evaporation deposits its load of 
soluble salts to form salt flats. Even beyond the Great 
Basin region, in arid sections salt's accumulate along 
the drainage channels and in the bottom lands. Alkali 
areas are, as a rule, not very extensive, and their extent 
and distribution can only be indicated on the map. 
Almost every drainage channel in the arid portions of 
the United States is lined with a narrow strip of alkali 
vegetation, and similar vegetation is found on the small 
salt flats along the coasts. The soils occupied by this 
type of vegetation are usually moist, but excessively 
supplied with salts. These salts are usually referred 
to as alkali, of which there are two types—white 
alkali and black alkali. The principal salts of white 
alkali are common salt (sodium chloride), Glauber’s 
salt (sulphate of soda), Epsom salt's (sulphate of 
magnesium), and bittern (magnesium chloride). 
These salts crystallize on the surface to form a white 
deposit known as “white alkali.” Black alkali is com¬ 
posed of sal soda (carbonate of soda), and known as 
“ black alkali ” because of its corrosive action on or¬ 
ganic matter. Where it occurs the leachings are dark 
in color and the deposited salt contains enough organic 
matter to give it a dark color. Black alkali is 
much more harmful to vegetation than white 
alkali. 
In appearance this desert shrub varies with 
the particular type of vegetation represented 
(figs. 57 to 60). It may present the uniform 
shrublike growth of pure greasewood, deep green 
during the growing period, but gray and monoto¬ 
nous during the drought or winter rest period; 
or a barren white salt surface with only here 
and there a dark green plant of samphire or 
pickleweed; or a grass cover with scattered tall 
plants of rabbit brush ; or lawnlike areas of pure 
salt grass. 
The salt desert shrub may be reduced to three 
main associations, with each of which may be 
grouped a number of minor associations or 
associes: 
Greasewood ( Sarcobatus rermiculatus). 
Greasewood-sliadseale (Sarcobatus vermiculatus- 
Atriplex confertifolia). 
Seepweed (Dondia torreyana). 
Pickleweed ( Allenrolfea occidentalis). 
Samphire (8 alicornia utahensis, 8. rubra, 8. 
ambigua ). 
Saltgrass (Distichlis spicata ) : 
Tussock grass (Sporobolns airoides ). 
Rabbit brush (Ohrysothamnus graveolens). 
Alkali heath ( Frankenia grandiflora oampestris). 
Greasewood (fig. 57).—Greasewood plants {Sarco- 
batus vermiculatus) are evenly spaced, from 4 to 7 
feet apart, and range from 2 to 5 feet in height'. 
The plants are green in color, due to the succulent 
leaves, and when in full leaf present a relatively lux¬ 
uriant appearance, contrasting sharply with the gray of 
the shadscale or sagebrush. The soil between the plants 
is often covered with little or no perennial growth. 
Greasewood is widely distributed, ranging throughout 
the northern and much of the southern desert. The 
most extensive areas are usually only a few miles across 
and lie near the bottom of the valleys or along drainage 
channels. Land of this type contains harmful amounts 
of salt and is usually supplied with ground water dur¬ 
ing a part of the year. It has been successfully irri¬ 
gated, and much of the best agricultural land of the 
lower portions of the Great Basin previously bore this 
type of vegetation. 
Greasewoodr-shadscale. —Between the northern desert 
shrub and the salt desert shrub in the Great Basin 
Figure 56.—Lechuguilla and sotol. (Creosote bush.) Many desert, shrubs, a 
few cacti, and resurrection plants occur in this type. It is not agricultural land. San¬ 
derson, Tex. 
