ACKNOWLEDGEMENTS 



In the preparation of this bulletin the authors have had the 

 kindly and valuable personal assistance of Dr. A. S. Hitchcock, Dr. 

 David Griffiths, Dr. F. V. Coville and Mrs. Agnes Chase on many 

 occasions. Dr. Hitchcock in particular placed the grass collection 

 of the National Herbarium and the library of that division at our 

 disposal and gave us freely of his advice and experience. Dr. F. 

 V. Coville kindly assisted us in the determination of the species 

 of Juncus. To say that we appreciated the services rendered by 

 these scientific workers and are grateful for their assistance ex- 

 presses but mildly the obligations under which we feel ourselves 

 placed. 



The Life Zone Map is a copy of one prepared by Mr. Vernon 

 Bailey in the Bureau of the Biological Survey, and we are permitted 

 to publisii i( luough the courtesy of Dr. H. W. Henshaw, Chief of 

 ttiat Bureau. We certainly are thankful for this privilege sine?: It 

 t'^so materially improves and crystallizes the information contained 

 in this bu'letin. 



We are also indebted to the Department of Agriculture for 

 the excellent figures with which we are able to illustrate the bulle- 

 tin. 



In the preparation of the keys, the latest manuals and other 

 publications relating to grasses have been freely used without cita- 

 /ii^on ; and we wish to give public expression here of our indebtedness 

 tvi 'Rydberg's Flora of Colorado, Coulter and Nelson's New Manual of 

 the Rocky Mountain Region. Small's Flora of the Southeastern 

 States, and the various publications of the United States Depart- 

 ment of Agriculture, especially the division of Agrostology bulletins 

 as well as the contributions from the National Herbarium, all of 

 which have been in continuous use. 



The authors are indebted to the Arizona Experiment Station 

 for the use of ten plates showing various grasses, credit being 

 given under each plate- 



