iv PREFACE. 



The work is illustrated throughout, and the student is advised 

 to consult the illustrations freely, not only on account of their 

 value in elucidating the descriptions, but also because the legends 

 contain information which in some instances supplements that 

 given in the text. 



It should be stated that a large proportion of the illustrations 

 are reproductions af photographs and drawings made by the 

 author, and that in all cases where illustrations are borrowed, 

 credit is given each author in connection with the reproduction. 



One of the most difficult questions which arises in writing 

 a work of this kind is that relating to nomenclature. Owing to 

 the desirability of maintaining a stable nomenclature, particularly 

 for medicinal plants, the author has adopted a rather conservative 

 course and has been largely guided by Engler & Prantl and Index 

 Kewensis, or, in the case of plants growing in the United States, 

 the names gi^'en in Britton's Flora may have been employed. 



Among the works consulted by the author, and of which special 

 mention should be made, are the following: Organography of 

 Plants by K. Goebel (English translation by Isaac Bayley Bal- 

 four) ; The Physiology of Plants by W. Pfeffer (second revised 

 English edition by Alfred J. Ewart) ; Die Heilpflanzen by Georg 

 Dragendorfif ; The Volatile Oils by Gildemeister & Hoffmann 

 (English translation by Edwafd Kremers) ; Die Pflanzen- 

 Alkaloide by Jul. Wilh. Bruhl, E. Hjelt and O. Aschan. 



Grateful acknowledgment is also made to the following pub- 

 lishers for permission to reproduce illustrations from the works 

 mentioned. Wilhelm Engelmann, of Leipzig: Die naturlichen 

 Pflanzen-familien by Engler & Prantl. Gebruder Borntraeger, 

 of Berlin : Handbuch der systematische Botanik by E. Warming. 

 Weidmannsche Buchhandlung, of Berlin : Wissenschaftliche 

 Drogenkunde by Arthur Meyer. Gustav Fischer, of Jena : Lehr- 

 buch der Botanik by Strasburger, Noll, Schenck and Schimper. 



The author desires fully to acknowledge the services of Miss 

 Florence Yaple, vvithout whose painstaking and constant assist- 

 ance during the course of revision, this book could not have 

 appeared in its present enlarged form. 



H. K. 

 April, 1907. 



