PREFATORY NOTE. 



Early in its administration of the National Forests the Forest 

 Service was confronted with the problem of restoring the vegetation 

 on many areas on which the natural ground cover had been com- 

 pletely or partially wiped out by destructive overgrazing before the 

 areas were included in National Forests. In order to secure the 

 fundamental information on which beneficial changes in the prac- 

 tice of grazing on such areas might be based the Forest Service 

 joined the Bureau of Plant Industry in 1907 in a cooperative project 

 of grazing investigations. Several important reports have been pub- 

 lished, embodying the results of these various field studies, and the 

 changes that have been made in the administration of grazing on 

 the National Forests in accordance with the results of the investiga- 

 tions have brought about conspicuous improvement in the ground 

 cover, great advance in the protection of watersheds, and important 

 increase in the number and quality of stock grazed. A part of the 

 original plan of investigation was to make a detailed study of the life 

 history of each important grazing plant for the special purpose of 

 determining its reproductive season, from the sending up of the flower 

 stalk to the maturing of the seed, and the period necessary to enable 

 the new seedlings to reach a size and vigor sufficient to withstand 

 moderate trampling by stock. In the course of these studies a very 

 large amount of detailed information about the important grazing 

 plants was acquired which could not be used in the more general 

 reports already published. In the paper now presented for publica- 

 tion a portion of this detailed information is given, in a form suited 

 to the needs of forest officers and of stock owners who desire to 

 familiarize themselves with the habits and requirements of the 

 plants upon which their animals subsist. Such knowledge is neces- 

 sary to the highest success in their business just as a knowledge of 

 the habits and requirements of cultivated plants is necessary to the 

 highest success in the business of the farmer. For the first time in 

 the history of grazing-plant literature the information needed to 

 accomplish this result has been acquired and presented for public uso< 



Frederick V. Coville, 

 Botanist, Bureau of Plant Industry. 



