CORRELATION BETWEEN CERTAIN 

 SPECIES OF PUCCINIA AND 

 UROMYCES' 



C. R. Orton 



(With Plates 70 and 71, Containing 12 Figures) 



There are many interesting taxonomic problems which have 

 arisen in the work of preparing the Uredinales for North Amer- 

 ican Flora. One of these problems, which has been supple- 

 mented somewhat by cultures and field observations, bears di- 

 rectly upon the relationship existing between Puccinia and Uro- 

 myces. To bring out one feature of this relationship more clearly 

 than heretofore presented the writer has prepared this paper, 

 pointing out certain species in the two genera which are conspic- 

 uous because of their apparent morphological similarity and of 

 their occurrence upon the same or closely related hosts in both 

 gametophytic and sporophytic stages. The similar geographical 

 distribution of these correlated species appears in most cases to 

 afford some additional support to this relationship. 



A brief statement of the treatment of Uromyces and Puccinia 

 by the leading workers on the rusts, from Persoon's time to the 

 present, is here included for the purpose of a better understand- 

 ing of the taxonomic development of these genera. 



Persoon in 1794^ was the first to publish any clearly defined 

 work on fungi in which the Uredinales were included. In this 

 work he brought forward the name Puccinia, a name first used by 

 Micheli, a prebinomial author, and applied it to species of Phrag- 

 midium and those of other genera including three species ' of 

 Puccinia as we now use that genus. In the same work the genus 

 Uredo w^as established which contained four species now refer- 

 able to as many genera. The second species was Uredo Fabae 

 which is undoubtedly a Uromyces. In a later work^ by the same 



^ Read before the American Phytopathological Society at the Washington 

 meeting, Dec. 28, 1911. 



^ Neues Mag. Bot. i: 93. 1794. 

 ^ Syn. Fung, i: 220-230. 1801. 



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