Bui. 1227, U. S. Dept. of Agriculture. 



Plate IV. 



Fig. I. — Under Total Protection. 



In the plot from which prairie dogs and stock were excluded tall stems and fruiting heads 

 developed. (Measurements in the background are in feet.) 



Fig. 2. — Under Grazing by Prairie Dogs. 



Grazing by prairie dogs usually reduces this grass to the form of a close-set turf, with few or no 

 tall stems and frequently no fruiting heads whatever. 



BLUE GRAMA (BOUTELOUA GRACILIS) UNDER TOTAL PRO- 

 TECTION AND UNDER GRAZING BY PRAIRIE DOGS, COCO- 

 NINO, ARIZ., OCTOBER 29. 1920. 



