38 ASCOMYCETES 



in the fruit known as bladder plums, and occasionally on the young 

 branches. 



The plants of this order are characterized by the production of 

 asci separate from each other, usually standing side by side on the 

 surface of the affected leaf or other portion of the host. 



The families and genera may be distinguished by the following : 



Family i. Ascocorticiaceae. 



1. Saprophytic; asci standing close together on a basal membrane. A 



single genus and species. AscocoRTiciUM. 



Family 2. Exoascaceae. 



Parasitic ; asci free from each other, breaking out directly from the sur- 

 face of the host with no distinct membrane beneath. 2. 



2. Asci formed as swellings at the ends of mycelial threads which project 



between the cells of the host. Magnusiella. 



Asci springing from a more or less developed subcuticular mycelial 



layer. 3. 



3. Asci eight- (or sometimes four-) spored ; mycelium perennial. 



EXOASCUS 



Asci many-spored through the budding of the spores within the ascus. 



Taphria. 



Magnusiella contains two American species producing deformi- 

 ties, the one on Potciitilla Canadaisis and the other on Betula 

 populifera. Exoasctis has numerous species and includes those 

 producing deformities in drupaceous fruits. Most common are 

 E. deforina7ts causing the leaf- curl, and the various species pro- 

 ducing "bladder-plums" or "plum-pockets" from the ovaries of 

 various species of plum and cherry. Taphria^ contains several 

 species parasitic on Quercus, Populus, Rlnis copallmay etc. 



LITERATURE. 



Schroeter. Loc. cit. i 56-161. 



Saccardo. Sylloge Fungorum, 8: 811-820; 10: 6']-'ji\ 11: 



435-439- 



"^ This is the original fonn of the generic name. It was changed to 

 Taphrina because of the existence of a genus Taphria in zoology. This 

 limitation in nomenclature no longer exists, hence the return to the original 

 name. 



