114 
Journal of Agricultural Research 
Vol. XXVIII, No. 2 
It is a gray bush ranging from 2 to 5 feet in height, found mainly in chalky soils 
that contain more or less alkali. Dominant type on the bottom lands along Gila 
River, where it is found mainly in open stands. The type characterizes the 
most productive land of this region when it is placed under irrigation. It has a 
grazing value similar to that of Atriplex lentiformis. 
(85) Yucca Desert Grass. —Areas containing a scattered growth of yucca, 
usually Yucca radiosa (Englem.) Trel, over a grass cover composed usually of tobosa 
grass, are classified in this type. Yucca may also be distributed over areas char¬ 
acterized by Bouteloua rothrockii or Bouteloua eriopoda. It is common in New 
Mexico and eastern Arizona where it grows in rather loose open soils. Very 
little value for crop production without irrigation. The grasses in this type are 
palatable to livestock and the yucca is used to some extent as an emergency 
rstock feed during droughts. The carrying capacity of this type is 15 to 25 head 
per section. 
(86) Black Brush ( Flourensia cernua DC.).—The black brush type con¬ 
tains few if any other species of vegetation. It grows in rather dense stands in 
well-drained porous soils in southern New Mexico and eastern Arizona. It has 
no value for crop production unless irrigated. It is also nonpalatable to all 
classes of livestock. 
(87) Black Brush Grass. —Plate 14, B, illustrates a typical area supporting 
this type, which is made up of a scattered stand of black brush and a little creO- 
sotebush with varying densities of grasses, consisting mainly of tobosa, black 
grama, and false needlegrass ( Scleropogon brevifolius Phil.). This type is 
common in the semidesert regions of southern New Mexico and eastern Arizona. 
It characterizes lands that have little or no value for growing crops. With the 
exception of tobosa, which is only grazed when green, the other grasses are highly 
palatable to all classes of livestock. It has a carrying capacity of 10 to 20 head of 
cattle per section. 
(88) Nolina ( Nolina microcarpa S. Wats.).—Nolina, also known as bear grass, 
produces a dense tufted bunched growth having very coarse foliage, varying in 
height from 2 to 4 feet. It is common in rather dry rocky localities in southern 
New Mexico and Arizona. It is not grazed owing to its tough character, and the 
localities where it grows are usually too rocky to have any value for producing crops. 
(89) Shinnery ( Quercus havardii Rydb.).—This type, which is illustrated by 
Plate 15, A, is very common over the sandhills of New Mexico, Texas, and 
probably in western Oklahoma. It consists largely of an even distribution of 
the low-growing shinnery, seldom exceeding 2 feet in height. It often contains 
a scattered growth of mesquite. Browsed to a limited extent by livestock. It is 
very important in years of drought when other feed is very scarce. It is re¬ 
ported to be poisonous to cattle when the leaves are budding out. Shinnery 
lands are too sandy to be used for crop production. 
(90) Willow ( Salix sp.). —This type is restricted to narrow strips along creeks 
or other wet or moist places in the mountainous regions of the West, at 
elevations where the growing season is frequently too short to mature grain 
crops. Willows are also frequently found in small patches in wet meadows. 
Unless the willows are very dense a good undergrowth of sedges, rushes, and 
grasses is produced which are very palatable to sheep and cattle and thus give 
the land a high carrying capacity. 
(91) Mountain Brush. —This type, shown by Plate 15, B, includes all brush 
land where chokecherry ( Prunus melanocarpa (A. Nels.) Rydb.), snowberry 
(Symphoricarpos sp.), shadblow(A mdanchier sp.), oak brush (Quercus utahensis 
(A. DC.) Rydb.), scrub maple ( Acer sp.), river hawthorn (Crataegus 
rivularis Nutt.), and sagebrush are the predominant shrubs, occurring either 
in equal quantities or with one predominating and with one or none of the 
