TYPES OF AMERICAN GRASSES: A STUDY OF THE AMER- 

 ICAN SPECIES OF GRASSES DESCRIBED BY LINMJS, 

 GRONOYIUS, SLOANE, SWARTZ, AND MICHAUX. 



By A. S. Hitchcock. 



INTRODUCTION. 



During the spring of 1907 I had the opportunity of examining 

 many types of American species of grasses deposited in European 

 herbaria. In the present paper I have considered the species of 

 grasses described by Linngeus, Gronovius, Sloane, Swartz, and 

 Michaux, the first only so far as they are based upon American- ma- 

 terial. No attempt is made to determine the types of Old World 

 species. 



Since the older authors did not indicate their types, these must be 

 determined from the records which have been preserved. The type 

 specimen is the specimen or one of the specimens from which the 

 author drew up the description. The specimen often supplements 

 or interprets the description. If the author mentions in his original 

 description a definite specimen, if this specimen has been preserved 

 and its identity certified by the data upon the label and by the name 

 of the species added by the author, it is clear that this specimen is 

 the type. However, it often happens that the evidence is less com- 

 plete. An author may have based his description upon more than 

 one plant (Panicum pubescens Lam., see page 147) ; the supposed type 

 may not agree perfectly with the description (Andropogon ischaemum 

 L., page 126) ; the author may have written the name upon more than 

 one sheet or upon a sheet which is not mentioned in the description 

 (Panicum, latifolium L., page 118); the locality or other data on the 

 label of the type specimen may not agree with- that published 

 (Zizania jiuitans Michx., page 156) ; the type specimen may have been 

 sent to another herbarium (Panicum dichotomiflorum Michx., page 

 147) ; the type specimen may be accompanied by a specimen of a dif- 

 ferent species upon the same sheet (Panicum dichotomum L., page 1 17) ; 

 or the type specimen may bear a name on the label which is different 

 from the one published (CJiloris monostacJiya Michx., page 152); or 



113 



