THE GRAMA GRASSES: 

 BOUTELOUA AND RELATED GENERA. 



By David Griffiths. 



INTRODUCTION. 

 BASIS AND METHODS OF THE WORK. 



It was during the writer's connection with the University of Arizona 

 in 1900 that work was begun on this group of plants. Preparations 

 were then made to grow the plants under cultivation at the University 

 in a region where the species predominate in the grass flora and form 

 the main feed upon public and private stock ranges. A change of 

 location caused a change of the plan of work. Since 1901 the writer's 

 studies in the field have been carried on during extensive travel 

 on behalf of the Department of Agriculture for the study of the public 

 stock ranges and other purposes. In addition, travel has been per- 

 formed extensively in Mexico under conditions which have allowed 

 good opportunity for study. 



The material in the following herbaria has been examined : United 

 States National Herbarium, Gray Herbarium, herbarium of the Mis- 

 souri Botanical Garden, herbarium of the Field Museum of Natural 

 History, herbarium of the California Academy of Sciences (before 

 the fire), and the private herbaria of Brandegee and Tracy. But 

 while the collections in these herbaria were studied, the work is based 

 mainly upon the material in the United States National Herbarium, 

 and the specimens fisted are almost entirely from that repository. 



During his visit to Europe in 1907, Prof. A. S. Hitchcock secured, 

 through the kindness of the directors of the herbaria there, fragments 

 of several typical or authentic specimens for deposit in the National 

 Herbarium. In other cases he procured photographs of type speci- 

 mens and made notes and drawings that have greatly aided in the 

 interpretation of the older names of the species. Further information 

 has been obtained through correspondence with the directors of the 

 botanical gardens at Kew and Berlin, to whom acknowledgments 

 are due for their courtesy. 



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