Apr. 12,1924 Vegetation in the Semiarid Portion of the United States 117 
KEY TO AGRICULTURAL POSSIBILITIES OF VEGETATION TYPES 
The natural vegetation as a rule does not indicate favorable or unfavorable 
topography or the tillable or untillable character of the soil. It does, however, 
serve as an index to the potential possibilities of the habitat for growing other 
plants. A few of the types described in this paper may cover a large area, 
representing a considerable range in growing conditions. Any existing difference 
will be shown, however, in the density and thrift of the stand of vegetation 
even where there are not any special plants present to indicate changes. On 
a large area of the range lands of the West, especially the unreserved public 
domain, overgrazing has changed the natural stand of vegetation to such an 
extent that the plants now growing on the land can not be used as an indicator 
of the agricultural possibilities. Overgrazed areas can be readily identified by 
the replacement of thq more tender and succulent plants by tougher and non- 
palatable species and by the roots of the vegetation being exposed by tramping. 
In the following key the types are listed roughly in order of the value of the 
3ands they occupy for the production of cultivated crops. Since some of the 
types cover a wide range of growing conditions, they may be found on locations 
better or poorer than are indicated by this key. 
The types are listed in two general classes: (1) Those indicating favorable 
possibilities for growing crops by dry farming, and (2) those indicating lands 
where cultivated crops can not be successfully produced by dry farming and 
are therefore mainly valuable for grazing. The types indicating favorable 
conditions for dry farming are also divided into two classes: (a) Those that 
indicate favorable possibilities for producing grain cereals, and (6) those indi¬ 
cating lands that are suitable for the production of forage crops. Each of these 
groups is further divided into three general classes—best, medium, and poorest 
types. 
1. Dry farm land. —Lands which under proper cultivation are capable of 
producing crops without irrigation more valuable than the natural vegetation. 
(a) Grain land .—Types indicating lands suitable for the production of small 
grains. 
Best types: 
(11) Grama grass and valley sage. 
(12) Grama grass and western needle- 
grass. 
(24) Western needlegrass. 
(5) Grama grass and mountain sage. 
% 
Medium types: 
(42) Arizona fescue. 
(39) Wheat bunchgrass. 
(17) Grama-buffalo and wild alfalfa. 
(47) Dry meadow. 
(53) Antelope-brush. 
(22) Wire needlegrass. 
(13) Grama-buffalo grass. 
(16) Grama-buffalo and wheatgrass. 
Poorest types: 
(49) Sagebrush. 
(21) Wheatgrass. 
(3) Grama grass and niggerwool. 
(7) Grama grass and sagebrush. 
(9) Grama grass and wild alfalfa. 
(91) Mountain brush land. 
(40) Curly bunchgrass. 
(4) Grama grass, niggerwool, and 
Junegrass. 
(45) Weed grass. 
(15) Grama-buffalo and wire needle¬ 
grass. 
(14) Grama-buffalo and western nee¬ 
dle-grass. 
(2) Grama grass and wheatgrass. 
(96) Oak brush. 
(56) Little rabbitbrush. 
(1) Grama grass. 
(44) Giant wild-rye. 
