148 ROOT DEVELOPMENT IN THE GRASSLAND FORMATION. 



The root development of crop-plant ecads grown in plats on upland 

 and lowland areas was found to be greater on the upland in most cases 

 and uniformly so in relation to shoot development. This correlates 

 with the root development of certain native species in similar habitats. 

 The variations in plant behavior appear to be a response to differences 

 in evaporating power of the air and water-content of soil, although 

 differences in the abundance and distribution of nutrients probably 

 also play a part. 



A knowledge of the development, position, and competition of roots 

 is indispensable in explaining the phenomena of succession. Since root 

 position so clearly reflects the moisture conditions of the soil, especially 

 when interpreted in its community relations, a study of the root habits 

 of plants greatly increases our knowledge of the value of various species 

 in indicating lands of agricultural or non-agricultural value, and aids 

 us in selecting the kind of crop to be most profitably grown, as well as in 

 determining the proper methods of tillage. A study of the root de- 

 velopment of crop plants in the various plant associations renders more 

 accurate our interpretation of the indicator significance of the natural 

 vegetation. The great depth reached by crop plants under the true- 

 prairie environment indicates that they, like many native species, must 

 rely largely upon the deeper portions of their root systems for water 

 and solutes when approaching maturity, and especially during periods 

 of drought. This suggests the problem of determining the actively 

 absorbing areas of plants at various stages throughout their develop- 

 ment. The applications of such knowledge to agricultural practice 

 are patent. 



