190 



ASCOMYCETES. 



fertilise the trichogyne and cause it to develop as an 

 ascogonium. 



P. ochraceum (Wahlenb.) {P. fulviom D. C.) causes yellowish- 

 red spots on leaves of Prurnis Padios. 



P. obscurum Juel. produces thickened leaf-spots on Astragalus 

 alpinus and A. oroboides; on the under side these are whitish, 

 on the upper side they show the spermogonia as red points. 



The damage caused by Polystigma is easily kept in check 

 by burning infected leaves in autumn. 



Epichloe. 



The stromata form on the stems of grasses yellowish mould- 

 like coatings in which the flask-shaped perithecia are embedded. 



Fig. S3. — Epichloe ii/phina, forroing numerous white cushions, which completely 

 encircle the grass-stems, (v. Tubeuf phot.) 



The asci are cylindrical, and contain eight thread-like imicellular 



