MYCOLOGIA 



Vol. Ill March, 191 1 No. 2 



STUDIES IN NORTH AMERICAN 

 HYPHOMYCETES— I 



The Genera Rhinotrichum and Olpitrichum 



David Ross Sumstine 

 (With Plates 37-39, Containing 40 Figures) 



This group of fungi is a heterogeneous mass of unrelated genera 

 and species and seems to have been rather studiously avoided by 

 American mycologists. The literature on the North American 

 species is exceedingly rare. Several genera of leaf parasites have 

 been studied but otherwise little has been done in the group. 

 Pound and Clements* have re-arranged the whole group with 

 reference to the North American species. 



Many species are known to be the conidial stages of ascomycetes 

 and should be excluded from the group. The following genera 

 contain species that have been definitely associated with other 

 fungi, Oidium, Polythrincium, Verticillium, Diplocladium, Dac- 

 tylium, Mycogone,, Acrostalagmus, Sepedonium, Isaria, Hadro- 

 trichufH, Oedocephalum. 



Some genera are autonomous but a study of their structure 

 and their fructification shows that their affinity is with other 

 groups. Among such genera are the following: Microstroma, 

 Myxotrichum, Aspergillus, Penicillium, Zygodesmus. 



With our limited knowledge of this perplexing group it is better 

 to defer the arrangement of it until a more exhaustive study of 

 the genera and species has been made. 



* Minn. Bot. Studies 9: 644-673. 1896. Ibid. 726-738. 1897. 

 [Mycologia for January, 1911 (3: 1-44), was issued January 31, 191 1] 



45 



