Hedgcock, Hunt, Hahn: Coleosporium 189 



them, Elephantopus only. During the same period, 23 sets of 

 inoculations have been made from aecial material adjudged to be 

 the aecia of Coleosporium elephant opodis ; of these, 17 infected 

 only plants of species of Elephantopus, 6 infected plants of 

 species of both Elephantopus and Vernonia, while in no case were 

 those of Vernonia alone infected. 



From 1916 to 1919, 10 sets of inoculations were made with 

 aecial material grown in the greenhouse at Washington, D. C, by 

 inoculating pines in incubation chambers with sporidia from the 

 fresh telia of Coleosporium elephant opodis. In all of these 

 sets, plants of species of Elephantopus were infected, those of 

 Vernonia in each set remaining free from infection. During the 

 same period, aecial material of Coleosporium carneum grown in 

 the same manner was used in 4 sets of experiments with the 

 result that only plants of species of Vernonia were infected, those 

 of Elephantopus in each set remaining free from infection. 



From 1914 to 1919, 7 sets of inoculations were made with 

 the urediniospores of Coleosporium elephantopodis resulting in 

 the infection only of plants of species of Elephantopus, those of 

 Vernonia in each set remaining free from infection. During the 

 same period 8 sets of inoculations were made with the uredinio- 

 spores of Coleosporium carneum-, resulting in the infection only 

 of plants of species of Vernonia, those of Elephantopus in each 

 set remaining free from infection. From the foregoing results 

 we conclude that these two Coleosporiums are distinct species 

 physiologically. 



The Peridermium which infects plants of species of Elephan- 

 topus is very much less common than the one infecting plants of 

 species of Vernonia. The former fungus has fewer, smaller, 

 and lighter colored pycnia, which are ordinarily in shorter rows 

 than those of the latter. The aecia of the former are more com- 

 monly somewhat triangular in side view, and usually slightly 

 smaller. The peridial cells of the former usually do not overlap, 

 while those of the latter are commonly overlapping. The aecio- 

 spores and urediniospores of the former are slightly smaller 

 and more commonly globose and their cell walls are usually 

 nearly uniform in thickness, while those of the latter are fre- 

 quently distinctly thickened at the apex. 



