252 



[Vol. 9 



ANNALS OF THE MISSOURI BOTANICAL GARDEN 



is to follow phylogenetic lines. The question of the generic dis- 

 position of the various species is, of course, a question of phytog- 

 eny. 



^fiod-, jrecjucntlij rcfUxceU 



ficrennidta-- 



C -Cras&icdulis 



\ 



\ 



\ 

 I 



/ 



/ 



V 



\ 



\ 





C.sulfur eus - 



/ 







-—I 



caves «*-mip\e%icaul-- 



Fi^. 2. Phylogenetic chart of the species of Cauhinthus. 



Guillenia. — Most interesting, in the light of the present generic 

 limits of Caulanthus, is a consideration of those species desig- 

 nated by Dr. Greene as constituting a new genus — Guillenia. 

 Caulanthus lasiophyllus was designated as the type of that genus, 

 and with it and two of its varieties were associate* i C. flavescens, 

 C. Cooperi, and Strepta?ithella longirostris. As will be seen by 

 an examination of the phylogenetic chart of Caulanthus that 

 accompanies this paper, Guillenia is a monophyletic group. Dr. 

 Greene here united a group of closely related forms as a unit dis- 

 tinct from Thely podium. Guillenia cannot be maintained under 

 a broader generic concept and so becomes a part of the larger 



