NOTES ON SOME SPECIES OF 

 COLEOSPORIUM— I 



George G. Hedgcock and N. Rex Hunt 

 (With Plates 20 and 21) 



In a series of two papers it is proposed to give in brief detail 

 hitherto unpublished data including the results of many sets of 

 inoculations with the aecial, uredinial, and telial stages of a number 

 of species of Coleosporium. Many negative results are given be- 

 cause of a theory that has been advanced, at least privately by 

 some investigators, that in the eastern United States we probably 

 have only two or three species of Coleosporium. That there are 

 species of pine which act as natural bridging hosts which, if in- 

 fected by a given species of Coleosporium from a certain host 

 plant, may bear aecia whose aeciospores are capable of infecting 

 other host plants and producing a second species of Coleosporium. 

 This theory would ascribe to a species of pine the power to change 

 the nature of a rust to such an extent that it is able to infect host 

 plants which the urediniospores of the rust may not be able to 

 infect. Negative results have at least some value in proving or 

 disproving a theory, that value being determined largely by the 

 number of cases given, and the care with which the results are 

 obtained. None of the species of pine reported in this paper 

 appear to be bridging hosts, in the light of the results obtained 

 from our experiments. 



Coleosporium helianthi and Coleosporium inconspicuum 



The forms of Coleosporium occurring on species of Coreopsis, 

 Helianthus, Verbesina and Viguiera in North America were origi- 

 nally assigned by Prof. J. C. Arthur to Coleosporium helianthi 

 (Schw.) Arthur in 1907. 1 Peridermium inconspicuum Long was 

 discovered and named by Dr. W. H. Long in 1912. 2 The proof 



1 Arthur, J. C. North American Flora, Uredinales, Coleosporiaceae. 7: 

 93- 1907. 



2 Long, W. H. Two New Species of Rusts. Mycologia 4: 283, 284. 1912. 



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