202 BOTANICAL GAZETTE [SEPTEMBER 
In some of the draws the preponderance of Muhlenbergia gracil- 
lima is even more marked. Near the above quadrat, in a portion 
protected from grazing, a quadrat would show: 
Bouteloua oligostachya : 18 % Artemisia frigida . . 
Muhlenbergia gracillima. 2.5 Artemisia gnaphalodes 
Aristida longiseta. . . 4.5 Gutierrezia Sarothrae 
Chrysopsis villosa . 
Thelesperma gracile . 
Echinocereus viridiflorus. 
Opuntia polyacantha . 
Euphorbia robusta 
Sitanion elymoides 
Eriogonum alatum 
Pentstemon angustifolius . 
Carex pennsylvanica . 
rw PO CO 
mre NF ND OH eS 
Total surface covered, 27%. 
In a portion of the mesa which has been grazed, but not to such 
an extent as the first quadrat given, is found: 
Bouteloua oligostachya. . . 22% Artemisiafrigida . . - - - 570° 
uhlenbergia gracillima z 
It cannot be stated positively that this condition is entirely due 
to grazing. It seems likely, however, that grazing would favor the 
development of grasses and tend to destroy the other plants, partic: 
ularly the dicotyledons. There is a very noticeable difference > 
adjacent areas when one is protected from grazing. The prepot 
derance of Bouteloua oligostachya and Muhlenbergia gracillima, and 
the paucity of higher spermatophytes in the grazed area is the chie 
difference. This seems to be the exact condition which would come 
about by natural succession and the grazing in this case hastens this 
succession. The more primitive parts of the formation and those 
which have not been grazed are much alike. Grazing, when es 
too severe, favors the development of the facies of the formator: 
Still another condition due to grazing should be considered. 
Near Colorado City, and particularly in the region lying ba 
Colorado City and Colorado Springs, the grazing has been very 
severe. The result here has been first to drive out most plants pei 
than the grasses, and ultimately even to destroy Bouleloua oliga- 
stachya and Muhlenbergia gracillima to a great extent. A few seh 
such as Astragalus bisulcatus, Chrysothamnus graveolens, se" 
squarrosa, and others which are not touched by grazing an? 
still survive; but the character, aside from a few of these asoneagt 
now almost entirely marked by annuals. The successioP 
