130 ILLINOIS ACADEMY OF SCIENCE 



2. In both there is a well marked hydrarch succession 

 passing from the aquatics through the sedge-moor in a closely 

 comparable series of associations. 



3. Both possess a climax prairie-meadow association in 

 which herbaceous species other than grasses are fairly abun- 

 dant. 



Differences 



1. The two regions differ much, as has been shown, in 

 altitude, in temperature, in length of growing season and in 

 character of soil. 



2. The mountain region is distinguished by the greater 

 paucity of aquatic species. 



3. The mountain region exhibits a xerarch succession com- 

 parable to nothing found in Illinois. 



The writer gratefully acknowledges his indebtedness to two 

 of his students, Misses Nellie C. Henry and Minnie C. Frost, 

 for much of the data used in this paper. 



The University of Chicago. 



BIBLIOGRAPHY 



1. Ramaley, Francis. Northern Colorado Plant Communities with Special 

 Reference to Boulder Park. Univ. of Colo. Studies 7:223-236, 1910; and Grass 

 Flora of Tolland, Colorado, and Vicinity. Univ. Colo. Studies 9: 121-141. 1912. 



2. Robbins, W. W. Climatology and Vegetation in Colorado. Bot. Gaz. 49:156- 

 180, 1910. 



3. Harvey, E. M. Evaporation and Soil Moisture on the Prairies of Illinois. 

 Trans. 111. Acad. Sci. 6:92-99. 1913. 



4. Ramaley, Francis, and Mitchell, L. A. Ecological cross section of Boulder 

 Park, Colo. Univ. Colo. Studies 8:277-287, 1911. 



5. Cowles, H. C. The Physiographic Ecology of Chicago and Vicinity. Bot. 

 Gaz. 31:73-182. 1901. 



6. Ramaley, Francis. The Amount of Bare Ground in Some Mountain Grass- 

 lands. Bot. Gaz. 57:526-528. 1914. 



