GRAZING RANGES IN SOUTHERN ARIZONA. dad 
necting C and I on the map (fig. 2). It was difficult to find any 
black grama in the field.t In 1914 the perennial grasses had pushed 
northwestward along the Tucson road at least 14 miles, if not 2 
miles, farther than they extended about five years before, and were 
established about 1 mile farther west along the south side of the 
field. The crowfoot grama has reached the north fence, not as a 
pure stand, but as the most important element of a well-developed 
though not yet complete grass association. In this same area the 
black grama is now abundant and spreading. Along the west fence 
is an area where the black and wire gramas are becoming abundant 
and important. In the southwest corner is an area of a section or 
more where rayless goldenrod (/socoma hartwegii) showed a scat- 
tering growth in 1903.2 This same area is now thickly covered with 
large mature plants of this species (Pl. V, figs. 1 and 2), a large 
number of which are dying, probably as the result of the encroach- 
ment of the grasses which are gradually taking possession of the 
area.2 The rayless goldenrod is of no value as a forage plant and 
it is customary to think and speak of it as a range weed and a 
nuisance. But it certainly protects the soil from erosion, retards 
run-off, and furnishes conditions favorable to the germination of 
the grass seeds. The grasses will probably eventually crowd it out. 
One of the most noticeable features of the grass-covered area of 
the reserve is the prevalence of spots a few square yards in extent 
covered by an almost pure stand of some long-lived perennial grass. 
This habit is more or less characteristic of the black grama (J/uhlen- 
bergia porter), but especially true of the wire grama (Bouteloua 
eriopoda), and of a coarse grass called Heteropogon contortus (PI. 
III, fig. 2). The two first named are valuable forage plants; the last 
is usually considered undesirable. 
Measurements show what is very plain to simple observation, that 
the Heteropogon puts a relatively large crop of feed on the ground. 
But this feed is almost valueless while green because the animals do 
not like it, and the grass is usually avoided in the hay cutting because 
of the large, sharp seeds that hurt the mouths of the animals. In 
1914 about 100 pounds of this grass was cut and cured just before it 
commenced to seed. It made a very good quality of hay, which was 
eaten by one of the work horses with relish and in preference to old 
grama hay of the previous season. It would seem that this grass 
may have a possibility as a hay crop, if cut at the proper time. It is 
a long-lived, strong-rooted perennial that spreads by rootstocks and 
grows about 2 feet high. 
1 See Bureau of Plant Industry Bulletin 177, Pl. IV, fig. 1, photographed in November, 
1902. 
2 See Bureau of Plant Industry Bulletin 177, Pl. IV, fig. 2, photographed in June, 1903. 
2The comparative data here given are supported by the testimony of Mr. W. B. 
McCleary, who has known this range for the past 15 years and who drove over a large 
part of it with the writer in September, 1914, for the purpose of making comparisons. 
28465°—Bull. 367—16——3 
