Apr. 12,1924 Vegetation in the Semiarid Portion of the United States 113 
The former grows to a height of from 20 to 30 feet and is characterized by white 
straight spines. The type occurs in the desert regions of Arizona and California, 
where it is most frequently found on rocky ridges and foothills. It is of little or 
no grazing value and nonagricultural. 
(78) Mesquite. —Areas supporting little or no vegetative growth other than 
mesquite are classified in this type. This shrub, illustrated by Plate 13, B, varies 
in size from only a few feet to trees 30 feet high. It occupies a large acreage in 
southern New Mexico and Arizona and has considerable economic value for the 
stock feed supplied from the leaves and beans. The roots and the thicker stems 
also supply considerable fuel. Very common in deep fertile soil along drainage 
channels where subirrigation is usually received. The better types of this land 
are capable of producing forage crops such as sorghums, corn, and millet, during 
very favorable years. It has a carrying capacity of 5 to 15 head of cattle per 
section. 
(79) Mesquite and Chamiso {Atriplex canescens (Pursh) Nutt.).—All lands 
supporting a scattered growth of mesquite and chamiso, a shrub varying in 
height from 2 to 4 feet, are listed under this type. It is a very common type in 
southern New Mexico and Arizona, where it grows in clay loam soils. The 
mesquite trees are probably supported to a large extent by subsoil moisture. 
The agricultural possibilities of lands supporting this type are similar to those 
producing the preceding type. Chamiso is browsed extensively by cattle and 
sheep, making the type rather valuable for grazing. It has a carrying capacity 
of 20 to 30 head of cattle per section. 
(80) Mesquite and Mesquite Grass. —The vegetation in this type consists 
of a scattered growth of mesquite over grassland which is usually composed of 
crowfoot grama, black grama, or grama-buffalo grass in the transition zone to 
this type, and in Texas buffalo curly mesquite ( Hilaria cenchroides H. B. K.)„ 
It is usually characteristic of deep fertile loam soils. It is valuable grazing land, 
and where the grasses are mostly buffalo and curly mesquite, crops of cotton 
can be produced during the most favorable years. It has a carrying capacity 
of 20 to 30 head of cattle per section. 
* (81) Parosela arborescens (Torr.) Heller, and Lepidospartum squamatum A. 
Gray.—Parosela is a shrub from 3 to 6 feet high, with finely divided long leaves, 
the whole shrub presenting a misty or gray appearance and having deep indigo 
flowers. Lepidospartum squamatum is a rather low-growing shrub, harsh to the 
touch. This type is limited to the dry washes in southern Nevada and south¬ 
eastern California and adjacent regions. Both species are worthless for grazing, 
and owing to the aridity of the region where they grow, crops can not be raised 
without irrigation. 
(82) Pluchea ( Pluchea sericea (Nutt.) Coville).—Pluchea is a tall straight¬ 
stemmed shrub, that seldom branches and grows in rather dense thickets. It 
was used to a considerable extent by the Indians to make arrows. This species 
occurs on strongly alkaline soil in limited quantities in western Arizona and 
southeastern California. It characterizes lands worthless for crop production 
and grazing. 
(83) Atriplex lentiformis (Torr.) S. Wats.— Atriplex lentiformis is restricted 
to the low wet alkali lands of southeastern California, bordering salt lakes, par¬ 
ticularly Salton Sink. It grows in large hummocklike clumps 6 to 15 feet across. 
There is usually little growth between these plants, which are widely spaced. 
Lands producing this type are incapable of crop production without leaching 
out the excess amount of alkali. It is grazed by stock mainly during periods 
of drought when little forage is available. 
(84) Desert Sage ( Atriplex polycarpa S. Wats.).—Desert sage, which is also 
known as saltbush and desert saltbush, illustrated by Plate 14, A, is limited 
largely to southeastern California, western Arizona, and southern Nevada. 
