212 



THE FUNGI WHICH CAUSE PLANT DISEASE 



usually knot-like head; perithecia closely scattered, sunken in 

 the stroma with only the ostiole protruding, flask-shaped, the 

 walls scarcely distinguishable from the stroma; asci cylindric, 



il^2«* e 



Fig. 152. — C. purpurea. D, Sphacelia stage; E, germinated sclerotia; G, sec- 

 tion of stroma; H, section of a perithecium; J, ascus with spores. After 

 Tulasne. 



8-spored; spores hyaline, continuous. Some twelve or fifteen 

 species are recorded all affecting the ovaries of the Gramineae. 



C. purpurea (Fr.) Tul."^ 



Sclerotium elongate, more or less curved, and resembling a much 

 enlarged grain, after a period of rest producing few or many, 

 clustered or scattered stromata which are 0.5-1.5 cm. high; spore 



