b LEAFLETS. 



that genus. But habitally this type is wholly unconformed to 

 Dallingeria — as far from it as it is from typical Aster itself. 

 It is even less repugnant to Sericocarpus, as Nees himself observed. 

 But that genus has densely silky-villous achenes, while those of 

 the type in question are perfectly glabrous, white and almost 

 shining as well as rather strongly quadrangular and little or 

 not at all compressed. The pappus, too, is very clear white 

 even in maturest age and after long years in the herbarium ; 

 and this is not true of any of its supposed allies. And that the 

 bristles of the pappus are visibly dilated at tip is a character 

 here for the first time noted. By these marks, and by its almost 

 filiform disk-corollas which are always white, and the thick and 

 appressed involucral bracts, it must be admitted, rationally, in 

 the rank of a genus, which I purpose calling Un amia. 



Over and above the type species, which must be called 

 U. PTARMicoiDBS, the following seem specifically distinct: 



U. FASTIGIATA. Leaves narrower than in U. ptarmicoides, 

 entire, marked with a pair of lateral veins more or less distinctly 

 anastomosing with the not very much more conspicuous midvein, 

 the surface and margins scabrous ; inflorescence strict and fas- 

 tigiate, flat-topped, the peduncles closely bracteolate, the bract- 

 lets passing gradually into those of the turbinate involucre 

 which are acute. 



Apparently local in moist sandy lands along the southern 

 shore of Lake Michigan, the best specimens by L. M. Umbach, 

 at Pine, Indiana. The rays are evidently white, otherwise I 

 should have suspected it to be the var. lutescens of the type 

 species. The long almost imbricate-bracteolate peduncles, tur- 

 binate involucres, (campanulate in U. ptarmicoides) and f astigiate 

 cyme compel the recognition of this as at least a strong sub 

 species. 



U. Gborgiaka. a. ptarmicoides, var. Georgianus, Gray. In 

 habit like the last, but less strongly fastigiate, the cyme not 

 flat-topped, the lateral peduncles quite surpassing the terminal 

 head, all the peduncles strongly bracteolate and the involucre 

 still more acutely turbinate, the bracts narrow and acute, 

 glabrous even marginally. 



