NORTH AMKRK'AN I'A R ASITIC KXOASCK.K. lo^ 



Init the size and shajx- of the stalk-cells would alone warrant 

 •separation from the other Exoasci affecting' fruits, each of 

 wdiich also has stalk-cells and develops an hymenium only in 

 the Horal parts. The asci are cylindrical in shape, with 

 rounded or truncated apices: the stalk-cells are sometimes a 

 little pointed, and may extend sliohtly between the epidermal 

 cells, though thev generally have the effect of forming a 

 continuous kuer abo\e them. The spores are almost spher- 

 ical, 3-4.5// in diametei". Conidial formations sometimes occur 

 in the asci. 



ExoAscus CERAsi ( Fiickcl ] Sddcbccl'. Plate I. Fig. 4. 



Bibl. and Syn. : 

 /ixoasciis zjicsiicn' Aiic t. ifVmer. 



ML'chan "S^). Ellis A; Eveihart '89. 



Farlow '86. 



T(ip//r/iui dcfoninnis Auct. Amer. pp. 



Robinson "iSj. 



Jixoasciis dcfoniHDis. Auct. Amer. pp. 



Saccardo '89. 

 Briosi e Casara "(;i 



Exoa>cits rcrasi | Fuckel ) Sadebeck '93. 



For a part of the determination of this species I am indebted 

 to the kindness of Prof. Sadebeck. who examined diseased 

 leaves of Primus scroh'ini and decided that they were infected 

 by Jixoasciis ccrasi. lie had previously considered it solely 

 European. There is a deformation of the leaves and branches, 

 the latter becoming thickened and forming '• witches" brooms'' 

 ( Hexenbesen). The perennial m\celium at the beginning of 

 spring penetrates into the inner cells of the leaves and de- 

 velops, generally upon their under side, a sub-cuticular hyme- 

 nium, which produces the asci. The leaves become curled or 

 twisted and wrinkled and somewhat dark, but not cartilagi- 

 nous like leaves affected b}- Exoasnis deformans. The asci 

 are normally club-shaped, rounded at the top and rather 

 slender, in size 7 10x30 50,", but their variabilit}' is de- 



