CRYPTOMYCES 



259 



Bark fungus {Tympanis amspersa, Fries.) often occurs on 

 living bark of birch and poplar. Ascophores top-shaped, 

 20-40, springing from a stroma, closed at first, then exposing 

 the black disc, margin sprinkled with a little white meal at 

 first, wall of ascus thick, spores numerous, 1-2XC5 \i. 



Spermogonia in minute conceptacles of the stroma, usually 



Fig. 76. Tympanis conspersa. i, group 

 of fungi on wood. 2, section of same ; 



3, ascus containing numerous spores ; 



4, spores ; 5, conidia. Figs. 2-5 mag. 



mixed with the ascophores, spermatia cylindrical, 2-5 x 

 0-5-1 n. 



A variety called malt (Rehm.), having fewer ascophores, 4-10 

 in a cluster, occurs on bark of apple, hawthorn, mountain- 

 ash, and other rosaceous plants. 



CRYPTOMYCES (Grev.) 



Ascophores immersed in a white stroma covered by the 

 blackened epidermis which is firmly united to the black crust 

 of the stroma, finally opening by long cracks ; asci cylindrical, 

 8-spored ; spores continuous, hyaline, elliptical. 



Forming large black patches on branches, superficially 

 resembling Rhytisma, differing in the spores and white 

 stroma. 



