164 



COMPARATIVE MORPHOLOGY OF FUNGI 



Because of this variation in the subordinate characters and the 

 similarity of the more important characters, the systematic classification 

 of the Taphrinales is confused. For a time, the forms with 4- or 8- 

 spored asci were placed in Exoascus, the forms in which the germination 

 of ascospores to sprout mycelium occurs in the asci in Taphrina (Sade- 

 beck, 1884). This distinction has been shown untenable however, and 

 consequently both genera must be united; for this the name Taphrina 

 possesses priority. The forms in which the asci are not catenulate and 

 intercalary, but single and terminal on branches which penetrate between 

 the epidermal cells, are occasionally placed in Magnusiella: thus the 



Fig. 102. : — Taphrina Potcntillae. 1 to 3. Development of ascus. Taphrina epiphylla. 

 4. Ascus before spore formation. Taphrina Pruni. 5 to 8. Development of ascus. 

 (1, 2, 5, 6 X 1,000; 3, 7, 8 X 1,265; 4 X 670; after Juel, 1921.) 



mycelium of T. {Magnusiella) Potentillae forms a continuous layer under 

 the epidermis; from these there rise to the surface, between the epidermal 

 cells, hyphal branches which grow toward the cuticle, each changing its 

 end to an ascus (Fig. 102, 1 to 3). True chlamydospores are not formed 

 in this case; this genus, however, is connected directly with Taphrina 

 by transitional forms. 



At present the Taphrinales include only parasitic forms which only 

 recently have been demonstrated cultivatable in artificial media (Martin 

 1925), and which mainly occur in temperate zones, rarely in the tropics. 

 They are specialized on three groups of cormophytes in three lines which 

 are more or less sharply distinguished by the form of their asci (Giesen- 



