190 



A8C0MYCETES. 



fertilise the trichogyiie and cause it to develop as an 

 ascogoniuni. 



P. ochraceum (Wahlenb.) (P. fulinim Y). C.) causes yellowisli- 

 I'fd spots on leaves of Primus Fadus. 



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

 alpinus and A. orohoides; 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 

 liy 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. 



Fio. S3,— EjHchlod lypUna, forming numerous white cushions, wliich completely 

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



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



