PREFACE 



This paper, by Dr. Lyman B. Smith, associate curator of the De- 

 partment of Botany, U. S. National Museum, is based on 25 years of 

 study in the United States, Europe, and Brazil. Much of the paper 

 has been derived from an unpublished manuscript prepared for the 

 "Flora Brasilica" of the Instituto de Botanica of Sao Paulo. How- 

 ever, in order to make a more compact work appropriate for the field 

 as well as the herbarium, bibliography has been limited to that strictly 

 essential in Brazil and descriptions have been eliminated in favor of 

 ampler keys. 



Illustrations are provided in a proportion slightly better than one 

 to every five species but are irregularly apportioned in order to sup- 

 port the key to the best effect and to cover all the 39 new species 

 proposed. 



Jason R. Swallen 



Head Curator, Department of Botany 



U. S. National Museum 



