2<)2 JOHN ERNST WEAVER 



6 or 8 feet, 9 while Ten Eyck has shown that at the same station 

 Andropogon furcatus reaches depths of 4.5-6.5 feet. 10 Likewise, 

 Shantz 11 in his extensive studies on the Great Plains, has shown 

 that the Prairie grass formation (characterized by the deep- 

 rooted Andropogon scoparius, A. halli, Psoralea tenuiflora, 

 Redfieldia flexuosa and others) is limited in its western extension 

 by insufficient (deep) water supply, and is replaced by the shal- 

 low-rooted short grass formation. 



The roots studied are remarkable for their individuality. The 

 roots of each species, because of peculiarities of form, of branch- 

 ing habit, of position in the soil, of texture, color, odor or taste, 

 can easily be distinguished, and these distinguishing characters 

 have often proved useful in ecological work. 



A knowledge of the distribution and extent of root-systems 

 helps us to more coreectly interpret the present structure of 

 vegetation as well as to analyze the causes which have led up to 

 and are constantly active in modifying these conditions. 



In concluding, I wish to acknowledge my deep indebtedness 

 to my onetime student, Mr. Walter L. C. Muenscher, whose 

 keen interest in the work made him my almost constant com- 

 panion in the course of this study. 



9 Georgeson, C. C. and Payne, J. E., Bui. 75 Kans. Agric. Col., 1897. 



10 Ten Eyck, A. M., Bui. 127 Kans. Agric. Col., 1904. 



11 Shantz, H. L., Natural Vegetation as an Indicator of the Capabilities of 

 Land for Crop Production in The Great Plains Area. Bui. 201 Bureau of Plant 

 Industry, 1911. 



