PREFACE 7 



1905, it was fortunately possible to reach a substantial agreement 

 on the controversial subject of nomenclature. Some mutual con- 

 cessions were necessary, but it is believed that they will be cheer- 

 fully made by those who are really seeking harmony in this matter. 

 The editors have, therefore, scrupulously endeavored to bring the 

 nomenclature of the Manual into accord with the Vienna agreement, 

 in order that American botanical nomenclature may be freed as 

 speedily as possible from peculiarity or provincialism and assume 

 the form which has received international sanction. The most im- 

 portant change in this respect which characterizes the present edition 

 in distinction from the previous editions is the adoption of the earliest 

 specific name instead of that specific name which was first combined 

 with the correct generic name. With this change it becomes more 

 important to trace the previous use of specific names under other 

 genera, and, to facilitate this, it seems wise to adopt the double 

 citation of authorities. In the capitalization of specific and varietal 

 names, it has been thought best to adopt the custom of many promi- 

 nent botanists from Linnaeus himself to the distinguished editors 

 of the Index Kewensis. The chief change in this respect from the 

 usage of previous editions consists in the decapitalization of geo- 

 graphic adjectives, such as canadensis, americana, and the like. In 

 regard to these words it should be borne in mind that they are not 

 English and therefore not subject to the rules of English grammar. 

 They are a part of an international system of Latin nomenclature, 

 which should not be modified by different nations by introducing 

 peculiarities of their several languages. Many generic and other 

 names, which were in use prior to 1753, were adopted by Linnaeus 

 and his followers. These names are indicated in the Manual by 

 brackets inclosing the name of the pre-Linnean author ; thus, Poly- 

 liodium [Tourn.] L. 



In the treatment of the ever increasing number of foreign plants 

 which have been recorded within our range, it has seemed desirable 

 to include in the Manual only those which have given some evidence 

 of self-dissemination and shown some tendency to become permanent 

 members of our flora. Waifs, ballast-weeds, and plants persisting 

 locally after cultivation have in general been omitted. 



During the last twenty years there has been an unprecedented 

 activity in the characterization of new species and varieties within 

 our range. The present editors have considerably delayed the 

 issue of this work in order to examine these new propositions 

 and give them recognition in all cases where their merit could be 



