i v INTRODUCTION 



While many lists of plants occurring in certain restricted localities 

 have been published, as far as I am aware no manual with full descrip- 

 tions and keys devoted to but one county and professing to include all 

 the species found in that county has ever been published in the United 

 States. That I have attempted here. The book is intended for the use 

 of students, and has been made as easy and as simple as possible. For 

 that reason no attempt has been made to use natural keys, for such keys 

 are always so full of exceptions as to make them worse than useless to the 

 beginner. Therefore artificial keys have been constructed and used. 

 The results obtained by the use of these keys can in each case be verified 

 by the more enlarged and technical descriptions appearing under the 

 families, genera and species respectively. 



It is hardly necessary to dwell upon the manifest advantages possessed 

 by a manual of this character for local use over those which deal with 

 areas embracing many states. Two-thirds or three-fourths of the species 

 described in such works will not be found in any given locality, and the 

 pupil cannot fail to be hindered by the necessity of studying the descrip- 

 tions of these species in order to differentiate them from those species 

 which actually occur in his vicinity. This, added to the fact that in a 

 local manual the exact locality in which any certain species can be found 

 is given, is sufficient to show the advantages of such a work. 



The descriptions here given are in most cases drawn from specimens 

 collected in this county by^myself and others. Where that has not been 

 possible specimens collected elsewhere have been resorted to, and in one 

 or two cases published descriptions have been used, specimens of these 

 species not being available. These descriptions have been further com- 

 pared with those of the standard manuals and are believed to be accurate 

 as applied to the species found here. In describing families and genera 

 the descriptions are applicable only to our own species, and exceptions 

 illustrated by foreign species have been omitted. Save that combina- 

 tions in which generic and specific name are identical are avoided, the 

 names used, with few exceptions, are those used in Britton's "Manual of 

 the Flora of the Northern States and Canada " and the sequence of families 

 and genera there adopted has been followed. This is largely true of the 

 sequence of species also. 



