TROCHILA POPULORUM DESM. 



C. W. Edgerton 



In a recent article, Potebnia* has called attention to the prob- 

 able connection between Marssonia Castagnei (Desm. and Mont.) 

 Sacc, a common fungus on certain species of Populus, and the 

 discomycete, Trochila Populorum Desm. This connection had 

 previously been suggested to him by Jaap. However, Potebnia is 

 of the opinion that the discomycete is a Pseudopeziza rather than 

 a Trochila. He arrived at this latter conclusion mostly from 

 the similarity of artificial cultures obtained from Marssonia 

 Castagnei spores, to cultures obtained from Pseudopeziza Salicis, 

 the perfect stage of Gloeosporium Salicis. His material of the 

 perfect stage of the Populus fungus was too scanty to be studied. 



During the past three years, I have had this fungus under 

 observation, trying to connect the Marssonia stage with the per- 

 fect form. While the study is not complete, and the connection 

 between the Marssonia and the Trochila is not absolutely proven, 

 it is impossible to carry on the study further on account of being 

 out of the region where the fungus grows, and it is thought best to 

 publish the observations as far as made. 



The study of the poplar Marssonia was commenced in the 

 summer of 1907, at Ithaca, New York. The fungus is very com- 

 mon in that region on Populus alba, forming numerous small dead 

 spots on the leaves. The acervuli develop in abundance on the 

 upper side of the spots. Two sorts of conidia develop in the 

 spots, the large two-celled spores typical of Marssonia, and some 

 small, somewhat cylindric to ellipsoid, one-celled spores. The 

 small spores have since been found by Potebnia and are illustrated 

 in his article. 



Pure cultures were obtained from the Marssonia spores on 

 sterilized bean pods in tubes. The fungus grew slowly, forming 

 a very much localized growth, with the development after some 

 time of the typical Marssonia spores. 



* Potebnia, A. Beitrage zur Micromycetenflora Mittel-Russlands. Ann. 

 Myc. 8 : 79-81. 1910. . . 



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