Jackson: New Rusts on Carduaceae 113 



light cinnamon-brown, thin, 1-1.5/x,, moderately and prominently 

 echinulate, the pores 2, opposite and equatorial. 



III. Telia amphigenous, scattered, round, small, 0.2-0.5 mm. in 

 diameter, early naked, pulvinate, becoming somewhat pulverulent, 

 blackish-brown, ruptured epidermis evident ; teliospores broadly or 

 narrowly ellipsoid, 23-26 by 27-48 ll, rounded at both ends, slightly 

 constricted at septum ; wall reddish chocolate-brown, concolorous, 

 medium-thick, 3-4 ll, slightly thicker above, 4-5 fi ; pedicel color- 

 less, about twice length of spore. 



On Carduaceae [Heliantheae] : 



Verbesina sp., Cuernavaca, Morelos, Mexico, Jan. 1908, E. 

 W. D. Holway (type). 



This species appears to differ sufficiently from other Verbesina 

 rusts to warrant specific rank. It is perhaps most closely related 

 to Puccinia abrupta Dietel and P. Verbesinae Schw. It differs 

 from the former in the less thickened apex of the teliospores and 

 in urediniospore characters. From the latter it differs in the con- 

 colorous teliospore wall and the thin-walled urediniospores. 



The Verbesina rusts have proven to be a difficult group and fur- 

 ther study based on more ample material will probably result in a 

 realignment of some of the species. The following key will serve 

 to indicate how the North American species have been separated 

 for the North American Flora: 



Telia only in the life history. P. ferox D. & H. 



Aecia or uredinia or both in life history. 



Teliospore-wall not over 7 [x thick at apex. 

 Telia early naked. 



Teliospore-wall lighter at apex, uredinial 



wall 1,5-2 p. P. Verbesinae Schw. 



Teliospore-wall concolorous, uredinial wall 



1— 1. 5 [x. P. vaga Jackson 



Telia long covered by epidermis. P. irregularis Dietel 



Teliospore-wall more than 7 fx thick above. 



Teliospores typically rounded below. P. abrupta Dietel 



Teliospores typically narrowed below. 



Teliospore-wall laminate. P. invetata Jackson 



Teliospore-wall not noticeably laminate. P. cognata Sydow 



Coleosporium Arnicale Arth. and Puccinia nuda Ellis & Ev. 



Coleosporium Arnicale Arth., described in 1907, was based on a 

 single collection made by W. N. Suksdorf in Falcon Valley, Wash- 



