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LETTER OF TRANSMITTAL. 



U. S. Department of Agriculture, 



Division of Agrostology, 

 Washington^ D. 6*1, January 15^ 1900. 

 Sir: I have the honor to transmit herewith and recommend for pub- 

 lication as Bulletin No. 21 of this Division, and under the general title 

 of "Studies on American Grasses," a revision of the North American 

 species of Chcetochloa. 



In our manuals of the plants of the northern United States four spe- 

 cies of Chcetochloa are described, all introduced, three being common 

 weeds, the fourth an occasional escape from cultivation. In Chap- 

 man's Southern Flora two additional and presumably native species 

 are enmnerated. In the paper here presented 28 North American spe- 

 cies are described, 23 of which are natives of this continent. Six 

 of the species enumerated are published here for the first time. 



Acknowledgments are due Dr. B. L. Robinson, curator of the Gray 

 Herbarium, for the loan of specimens and assistance in looking up 

 authorities, etc., and to J. H. Burchell, of the Kew Herbarium, for 

 assistance in the determinations by making comparisons with t3'pe 

 material. 



Respectfully, F. Lamson-Sgribner, 



Agi'ostologist. 



Hon. James Wilson, » 



Secretary of Agriculture. 



