and genera. Strict adherence to this sequence has resulted in the re- 

 taining of but one family name in some cases where several seem 

 more appropriate, and more in accordance with modern views. 



Many species described by Nuttall, Pursh, and other botanists 

 who really knew the plants they described from actual acquaintance 

 with them in the living state, have either been suppressed altogether, 

 or recorded as varieties by botanists who knew them only as herbar- 

 ium specimens. These species are constantly being reinstated by 

 field workers of to-day, and help to swell the list of names. 



There is also a growing tendency to discard the use of varietal 

 names, and to call all plants species which have characters enough to 

 justify the use of a distinctive name. Accordingly, many varieties 

 have been raised to specific rank, and may be looked for in their 

 proper place in the alphabetical arrangement of species. 



Several persons have suggested that the number given before 

 each species should not be changed, but remain the same in succes- 

 sive editions of this work, added species being indicated by a, b, etc. 

 The suggestion is a good one, but until the whole country is thor- 

 oughly worked over, and numerous genera pared down to their proper 

 limits) it does not seem possible. 



At the present rate of activity in taxonomic botany, the year 

 1905 will see 20,000 plant names to be listed, and many changes in 

 generic limits. 



It will be esteemed a favor if errors, however trivial, are reported, 

 as well as any plant names which do not appeaj in this book, and 

 which were published prior to October, 1900. It is suggested that 

 errors and omissions be noted on the printed page, or in red ink, in 

 order to easily distinguish them from the additions. 



While preparing the manuscript for this edition, it became ap- 

 parent that a number of new combinations would have to be pub- 

 lished in order to secure uniformity of treatment, some of which are 

 given below. 



Agropyroii Smitliii Palmeri (Scribn. & Smith) 



Agropyron spicatum Palmeri Scribn. & Smith, U. S. Dept. Ag. 

 Div. Agrost. Bull. 4: 33. 1897. 



Agropyron spicatiim inerine (Scribn. & Smith) 



Agropyron divergens inerme Scribn. & Smith, U. S. Dept. Ag. 

 Div. Agrost. Bull. 4:2;. 1897. 



Carex pratericola furva (Bailey) 



Carex pratensis var. furva Bailey; Macoun, Cat. Can. PI. %: 



377- l8 9- 



