ROOT DEVELOPMENT IN THE GRASSLAND FORMATION. 



INTRODUCTION. 



This book is intended to be a companion volume to "Ecological 

 Relations of Roots."* The latter may be considered a pioneer work 

 of rather an intensive nature, giving the results of investigations in 

 local areas in many widely separated plant communities. Since its 

 appearance investigations have been greatly extended and examina- 

 tions of the root systems of plants have been made at more than 25 

 stations in the grassland associations of Kansas, Colorado, South 

 Dakota, and Nebraska. Practically all of the grassland dominants 

 have now been studied, many of them in two or more associations and 

 under widely different conditions of environment. The descrip- 

 tions of 38 new root systems of important species of plants of prairie, 

 sandhills, and plains are included. A preliminary correlation of the 

 root development of certain crop plants, especially the cereals, with the 

 different types of the natural vegetation^ has been determined. More 

 than 80 examinations of the root systems of crop plants have been made 

 in widely varying soil types and conditions of growth. Investigations 

 were carried on at many stations in the prairie, mixed prairie, and 

 short-grass plains extending from the Missouri River to the Rocky 

 Mountains. A study was made also of the development of the root 

 systems of certain crop plants on sites at Lincoln, Nebraska, formerly 

 covered with and now adjoining typical high and low prairie. Aside 

 from a study of the root development of these crop plants in the two 

 habitats, some illuminating correlations with the root development of 

 native dominants have been found. For the proper setting of these 

 studies " Ecological Relations of Roots" forms the background. 



A knowledge of root development and distribution and of root com- 

 petition under different natural and cultural conditions is not only of 

 much practical value, but it also readily finds numerous scientific ap- 

 plications. The phenomena of plant succession, whether ecesis, com- 

 petition, or reaction, are controlled so largely by edaphic conditions 

 and particularly by water-content that they can be properly inter- 

 preted and their tiue significance understood only from a thorough 

 knowledge of root relations. It is obvious that a knowledge of root 

 habit is essential to the proper use of plants and plant communities as 

 indicators. The plant community has integrated all of the environ- 

 mental factors of its habitat ; it is the fundamental response to control- 

 ling conditions. The individual root habit and the community root 

 habit especially, together with the more familiar above-ground parts, 



*Carnegie Inst. Wash. Pub. No. 286. 



