190 



ASCOMYCETES. 



fertilise the trichogyne and cause it to develop as an 



ascogonmm. 



P. ochraceum (Wahlenb.) (P. fulvum D. C.) causes yellowish- 

 red spdts on leaves of Primus Pad us. 



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

 <il[,uiu.* and A. oroboidcs; on the under side these are whitish, 

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



The damage caused by Polystiyma, 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. 



I-'n;. 83. Epiehloii typhina, forming numerous white cushions, which completely 

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



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



