26o 



A TEXTBOOK OF THEORETICAL BOTANY 





Fig. 251. — Erysiphe grauiinis. Perithecia with 

 interlaced appendages. 



Perithecium 



Ascus 



X 



Fig. 252. — Erysiphe cichoracearum. Section through 

 mature perithecium showing two asci. 



Pezizales 



The Pezizales are Ascomycetes in which the fruiting bodies have an 

 outer covering which is either fleshy or leathery in texture. This definite 

 external layer, or peridium, is closed at first, but subsequently is pushed 



