TAPHRINA 



143 



Exoascus alni-incanae (Kiihn) causes enlargement of the 

 scales of alder catkins. The much enlarged scales project 

 from the catkins as reddish, fleshy, irregular outgrowths, 

 which become whitish at a later stage, due to the presence of 

 numerous asci. 



Exoascus carpini (Rostr.) forms dense witches' brooms on 

 hornbeam. The branches are thickened, stunted, and much 

 branched ; leaves crowded, somewhat curled, and bear the 

 asci on their under surface. 



Exoascus Johansonii (Sadeb.) caused deformation of the 

 carpels of poplar catkins, which assume a golden yellow 

 colour. Populus tremula and other species are attacked. 



TAPHRINA (Fries.) 



Forming more or less pronounced convex blisters on living 

 leaves. Asci produced on the concave surface of the 



Fig. 36. Taphrina bullata. 1, leaf of 

 pear-tree with blisters caused by the 

 fungus, reduced ; 2, asci on epidermis 

 of a leaf, highly mag. 



blisters, which are on the under surface of the leaves. 

 Mycelium not perennial in the tissues. 



The species are not as a rule injurious to any marked 

 extent. 



