XXXVII. VIOLET RUSTS OF NORTH AMERICA. 



J. C. ARTHUR AND E. W. D. HOLWAY. 



A rust of violets, in its three forms of aecidium, uredo and 

 teleutospore, is common throughout North America upon nearly 

 all indigenous species of the genus Viola. For the most part 

 it belongs to a single species, Puccinia Violce (ScnuM.) DC., 

 which is also the common violet rust of Europe and of some 

 other regions. This, at least, is the conclusion to which we 

 have arrived after a rather extended study of considerable ma- 

 terial. Beside the one common rust there is a peculiar sEcidium 

 throughout the eastern part of North America, and one species 

 of Puccinia in the western part, both distinctly American. 



In this connection we desire to acknowledge the kindness of 

 the New York Botanical Garden, the Botanical Department of 

 the University of Illinois, and of the Iowa State College, in 

 loaning material from their herbaria, and to extend our thanks 

 to their representatives. We wish also to thank Dr. J. J. Davis, 

 of Racine, Wis., and Mr. E. Bartholomew, of Rockport, Kans., 

 for aiding us with specimens and information. We are further- 

 more grateful to Mr. Stewardson Brown, curator of the herba- 

 rium of the Philadelphia Academy of Sciences, for the privilege 

 of examining material in the Schweinitz collection, and to the 

 custodians of the Gray Herbarium of Harvard University and 

 of the New England Botanical Club, from the examination of 

 whose phanerogamic collections of Viola, five specimens of rust 

 were obtained in the former instance and three in the latter. 



In this article for conciseness we have used in addition to 

 the usual I, II and III for designating the aecidium, uredo and 

 teleutospore stages, the sign O for the spermogonial stage. In 

 citing specimens these signs are put into large type when the 

 stage is present in abundance, and into small type when sub- 

 ordinate and in small amount. 



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