114 



THE ASCOMYCETES 



point of contact of two hvphae a pair of erect branches arises. 

 Each is separated from its parent hypha by a septum. One 

 branch, the oogonium, becomes ellipsoidal; the other remains 

 cylindrical and becomes closely applied to the oogonium, and a 

 cell, the antheridium, is cut off at its apex. The walls at the 



Fig. 64. Structural features of Erysiphaceae. A. Bulbous haustorium, a 

 type common among powdery mildews, in epidermal cell. B. Digitately 

 branched haustorium of Erysiphe graminis. C and D. Conidiophore and 

 conidia, the Oidium stage of powdery mildews. E. Types of dichoto- 

 mously branched tips of appendages. F. Types of uncinate or hooked tips 

 of appendages. G. Types of asci. H. Surface view of cleistocarp wall. 

 /. Appendage with bulbous base as in Fhyllactinia corylea. ]. Flexuous 

 appendage as among species of Erysiphe. {A and B adapted from Smith.) 



