Vail: Studies in the Asclepiadaceae 



427 



claimed for G. Caroiincnsh and the quadrate alternate divisions 

 belonging to G. hirsntus. It seemed entirely impossible with the 

 material at hand to draw any fast or hard line between them. The 

 polh'nia that have very marked characters in the other species seem 

 to be about the same in these two species and I could not find any 

 differences between those of the flowers labeled G, hirsutus and of 



J w 



those called G. Cavolinensis, 



These two Michauxian species 



constituted the older genus 



Vincctoxiatvi of Walter which leaves the third species G, lacvis 

 as the type of the genus Gonolohus. 



The type of Gonolobus lacvis is somewhat of a curiosity. 

 There is quite a good deal of it, small pieces mostly, but all 

 of the specimens in the two collections agree and point unmis- 

 takably to the plant since called Fjislcnia albida Nutt. {^Adi- 

 pdanus albida Britt., Bull. Torr. Bot. Club, 2i: 314). In the 

 Michaux Herbarium there are on a sheet a small specimen of G. 

 subcrosusl (the name and query are in Dr. Gray's"*" handwriting), 

 one angled follicle and one raceme, noted as G. lacvis^ also by 

 Dr. Gray, and two more leaves and two follicles. The old labels 

 read ''CynancJiuin capsidis lacvis'' and ''Gonolobus lacvis^ Illinois ^ 

 In the Richard Herbarium the specimens, consisting of some 

 leaves and one angled follicle, are much worm-eaten. They are 

 all, except the fragment of G. subcrosus^ Enslcnia albida. This 

 will clear up the discrepancy of the original description of G. 

 lacvis WTth the plants that have passed as such. ^' Folds quasi 

 conoidcO'Cordatis^ scnsiniaciitis ncrvis tantuin minutissinie ptibcrulis '' 

 describes certainly the leaves of Enslcnia albida^ but scarcely ac- 

 curately those of the so-called Gonolobus lacvis. The synonymy 

 of this plant should therefore be as follows : ' 



GoNOLOBUS LAEVis Michx. Fl. Bor. Am. i: 119. 1803 



Enslcnia albida Nutt. Gen. Am. l: 164. 18 18. ! 



Anipclanns albidus Britton, Bull. Torr. Bot Club, 21: 314. 



1894. 



4 



* Gonolobus suberosus and G. viacropJiyllus are very close in general appearance, 

 though the former has commonly yellowish-green leaves, with truncate base, and the 

 latter darker green leaves that have notably large rounded basal and often overlapping 

 lobes. 



