THE NORTH AMERICAN SPECIES OF PANICUM. 



By A. S. Hitchcock and Agnes Chase. 



INTRODUCTION. 



BASIS AND METHODS OF THE WORK. 



The present paper discusses the species of Panicum known to occur 

 in North America north of Panama, including the West Indies. The 

 results presented are based primarily upon the collections in the 

 United States National Herbarium. The collections of Panicum in 

 all the large herbaria in this country and in Europe have also been 

 examined. In addition to the work done on this large amount of 

 herbarium material both authors have carried on for several years 

 extensive field studies in all parts of the United States, as is indicated 

 by the specimens cited under "Distribution." A number of species 

 of the section Dichanthelium have been grown for several seasons 

 in the greenhouse in order to determine the relation between the 

 vernal and autumnal forms. 



AMERICAN HERBARIA EXAMINED. 



Biltmore, North Carolina. The Biltmore Herbarium, contain- 

 ing the types of most of the grasses published by Chapman in his 

 Flora of the Southern States. 



Cambridge. The Gray Herbarium of Harvard University. 



Chicago. The herbarium of the Field Museum of Natural History. 



New York City. The herbarium of the New York Botanical 

 Garden, at Bronx Park. The herbarium of Columbia University, 

 which is kept apart from the general herbarium of the Botanical 

 Garden, contains the Torrey Herbarium, each sheet of which is appro- 

 priately stamped. The private herbarium of Mr. George V. Nash is 

 also located at the Botanical Garden. 



Philadelphia. The herbarium of the Academy of Natural 

 Sciences of Philadelphia, containing the plants of Nuttall and Buckley 



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