288 BOTANICAL GAZETTE [OCTOBER 
invariable bunch habit far the more conspicuous. 4. scoparius 
(fig. 4) seems to form a very loose sod between the bunches of the 
former and extends lower down upon the slope, where in places it 
yields to the Boutelouas or rarely to Poa. In succession these forms 
seem to precede the Boutelouas. With a reduction of drainage 
and introduction of these sod-formers, the bunch-grasses yield, and 
in those portions of the prairie where succession has progressed most 
rven- 
__ Fic. 3.—Autumnal aspect: the bunch-grass, Andropogon jurcatus, with inte 
ng Spaces occupied by Bouteloua sod near crest of prairie knoll. 
rapidly, for example the northwestern exposure, the Andropogon 
and the “bunch-habit” are conditions of the past. With Agropyro” 
occidentale, the Andropogons and Sporobolus must be ranked as the 
pioneer grasses of the prairie, and as such hold a most important 
ecological relation in the structure and development of the formation. 
A. furcatus yields first, giving way to A. scoparius, which in pes 
assumes facial abundance and frequently persists in a somewhat 
anomalous way in the more mesophytic associations. These gr 
