Orton,: Correlation between Puccinia and Uromyces 197 



species would seem to indicate its still close relationship to Uro- 

 myces, and that its separation from the parent form has not yet 

 proceeded sufficiently far to obliterate every trace of its former 

 connexion." 



Hariot in his " Les Uredinees "^^ says that the autonomy of 

 Uromyces is a difficult question and that if it is to be kept as a 

 distinct genus it is only in order to follow the custom and to facil- 

 itate determinations. This statement seems very much to the 

 point, but the author does, however, treat the two genera as dis- 

 tinct in this work. 



P. & H. Sydow in their monograph of Uromyces^'^ state that 

 the genus differs from Puccinia only in the number of cells in the 

 teliospore, and they cite several comparative examples of both 

 the gametophytic and sporophytic generations of the two genera 

 to show this similarity. 



It is seen, then, that the name Puccinia was first applied to a 

 Gymnosporangium by Micheli, was later applied by Persoon to 

 Phragmidium with which a few species of Puccinia were included, 

 and was in 1816 separated by Link frorri Phragmidium and made 

 a genus as we now use it. 



The species of rusts now referable to the genus Uromyces were 

 first included by Persoon and his followers under Uredo. Later 

 it was included as a sub-genus of Puccinia by DeCandolle, and 

 was finally established technically as a genus by Unger in 1833 

 and put into general use by Fries in 1846. Since Fries' work all 

 uredinologists have treated it as a distinct genus differing from 

 Puccinia especially in its teliosporic character. 



The present paper is what the writer believes to be the first 

 attempt to list the correlated species in Puccinia and Uromyces 

 and is limited to a discussion of a few of the more prominent 

 types of correlation in the long-cycle forms only. 



The writer acknowledges the generous aid and counsel of Dr. 

 J. C. Arthur, without which the work would be impossible, and 

 grateful thanks are due Dr. F. D. Kern for many helpful sug- 

 gestions. 



The first example to attract special attention was furnished by 



"Les Uredinees 20. 1908. 



" Monog. Ured. 2 : vi-xi. 1909. • 



