PREFACE TO THE SECOND EDITION. 



The second edition of this Manual has been revised by the correc- 

 tion of the stereotyped plates, where practicable, and by the insertion 

 of descriptions of over one hundred aaditional species in the Appendix, 

 in order to attempt to present the greater part of the results reached 

 by students of our flora during the past three years. A large number 

 of synonyms have been added in the text, in order to make the book 

 more readily comparable with previously published works of a similar 

 character. To facilitate the more rapid determination of genera and 

 species, artificial keys to the families, prepared by Dr. Karl M. Wie- 

 gand of Cornell University, have been added to the preliminary matter, 

 and an artificial key to the genera of Composites, also written by him, 

 has been inserted immediately before the Appendix. 



In order to bring the species described in the Appendix into con- 

 sideration more readily, the words "See Appendix" have been added 

 after the generic name whenever a species is there described. 



N. L. B. 



New York Botanical Garden, November, 1904. 



NOTE TO THE THIRD EDITION. 



An Analytical Key to the Genera of the Grasses, prepared by Dr. 

 Karl M. Wiegand, has been added to this edition. 



N. L. B. 



February, 1907. 



