THE COMPARATIVE MORPHOLOGY, TAXONOMY AND 



DISTRIBUTION OF THE MYRICACEAE OF 



THE EASTERN UNITED STATES 



BY 



Heber Wilkinson Younglcen, A.M., M.S., Ph.D. 



With Plates LXXXI-XC 



(Thesis presented to the Faculty of the Graduate School 

 of the University of Pennsylvania, May 8, 1915, 

 in partial fulfilment of the requirements 

 for the degree of Doctor of Philosophy). 



I. Introduction 



The writer, during the past years of his activities as a botanical 

 teacher, examined minutely numerous drug plants along lines already 

 mapped out by Tschirch, Oesterle and other leading pharmacognosists. 

 In continuation of these studies and upon the kind suggestion of Professor 

 John M. Macfarlane, of the University of Pennsylvania, he undertook 

 the investigation of those species of the Myricaceae or Bayberry Family 

 that are indigenous to the eastern United States. 



This work was started during the winter of 1912 and has been carried 

 on continuously up to the present date. During this period extensive 

 studies have been made by the writer in the field, in the laboratory 

 and in the herbarium of the University of Pennsylvania, also in the 

 Academy of Natural Sciences of Philadelphia. The results already 

 secured are such that the writer trusts to gradually undertake a mono- 

 graphic account of the family, which presents many features of great 

 botanical interest. 



The writer desires to express his grateful appreciation to Professor 

 Macfarlane for his many valuable suggestions and untiring aid in the 

 direction and completion of the work. He would also thank his former 

 teacher and present esteemed colleague. Professor George H. Meeker, of 

 the Medico-Chirurgical College, for the opportunities which led to its 

 undertaking. 



