HEMIBASIDIOMYCETES 315 



basidiomycetes) were considered to have descended from 

 the Tilletiae. 



At a later date Moller established a new Order which he 

 called Protobasidiomycetes. This Order included six 

 families, Auricularieae, Uredineae, Pilacreae, Tremelleae, 

 Sirobasidieae, and Hyalorieae. Those families having 

 transversely septate basidia were supposed to spring from 

 Ustilago, whereas those with cruciately septate basidia 

 started from Tilletia. 



Moller does not consider that the Hemibasidiomycetes 

 give origin to the Basidiomycetes proper, an opinion 

 with which I am in agreement. I have previously expressed 

 my view that the Basidiomycetes evolved from conidial 

 forms of the Ascomycetes. 



I have followed Moller's arrangement of the Hemi- 

 basidiomycetes with the exception of including Ustilagineae 

 (including Ustilago and Tilletia) in the Order, with 

 which, morphologically, it appears to me to be in closest 

 agreement. 



KEY TO THE FAMILIES 



Obligate parasites. Spores either formed from the 

 ordinary mycelium or from special branches or sporo- 

 genous hyphae, either terminal or intercalary. On 

 germination the spores (chlamydospores or teleutospores) 

 produce a short promycelium ; this is either divided trans- 

 versely by 2-4, usually 3 septae, each cell bearing several 

 secondary spores (Ustilago); or the promycelium is con- 

 tinuous (not septate), and bears a cluster of secondary 

 spores at its apex ( Tilletia). Ustilagineae. 



Gymnocarpous. Sporophore more or less gelatinous; 



