114 THE AZALEAS OF NOKTH AMERICA 



The present study of American Azaleas is based chiefly on the 

 collections of the Arnold Arboretum. For many years Professor 

 Sargent has taken special interest in Azaleas and has succeeded 

 in assembling a large amount of material, particularly from the 

 southern states usually poorly represented in most herbaria. 

 Besides having this material at my disposal, I have consulted 

 the collections of the Gray Herbarium at Cambridge and of the 

 National Herbarium at Washington and the herbaria of the 

 New York Botanic Garden, the Academy of Natural Sciences of 

 Philadelphia, and of the New England Botanical Club; specimens 

 for further study were kindly loaned to me from most of these 

 institutions and from the herbaria of the State University of 

 Ohio, of the Missouri Botanical Garden and of the Academy of 

 Sciences at Rochester. I also am under obligation for specimens 

 to Professor W. C. Coker of the University of North Carolina, to 

 Dr. K. M. Wiegand of Cornell, Mr. W. W. Ashe of Washington 

 and Mr. John Dunbar of Rochester. I have further had the op- 

 portunity to see most of the species in their native habitats dur- 

 ing various journeys, and the living collections of Azaleas of this 

 Arboretum supplied me with material to study many of the 

 species and a large number of garden forms and hybrids in the 

 living state. The great variability of most species together with 

 the absence of strong morphological characters within this group 

 makes it difficult to assemble the numerous forms into well 

 defined species and varieties. The difficulty is considerably in- 

 creased if one tries to elucidate the innumerable garden forms 

 and hybrids, as few of these forms are adequately described 

 or figured and herbarium or living material of only a small per- 

 centage of them is available. 



The Azaleas form a distinct subgenus of the Rhododendron 

 for which we propose to use Endlicher's subgeneric name Anthc- 

 dendron, as we do not believe that the name Azalea used for it 

 by most authors can be correctly applied to this subgenus, as 

 will be seen from the following enumeration of synonyms and 

 the appended remarks. 



