MICROTHYRIACEAE 239 



celial branch, or a nodulate cell. Her data on this point are 

 summarized in Table 2. 



TABLE 2 

 Origin of Ascocarps Among Microthyriaceae 



The cells of the fructification are dark brown, being lighter 

 at the periphery, and are laid down in rows. This radiate charac- 

 teristic persists but may not be discernible in some genera unless 

 the material is cleared by boiling in potassium hydroxide. In 

 other genera the color is so dense as to be carbonaceous, making 

 it impossible, even by use of a clearing reagent, to determine 

 the arrangement of cells. In still other genera the central cells 

 gelatinize. 



Aloreijoella qiiercina, commonly occurring in the southeastern 

 United States on the foliage of various species of red oaks and 

 black oaks, is the most thoroughly known species of Micro- 

 thyriaceae. Luttrell (1940) observed that its mycelium is en- 

 tirely superficial during the early summer and that the hyphae 

 may fragment in a toruloid manner, each element being presum- 

 ably capable of functioning as a conidium. By late summer sub- 

 cuticular hyphae are present. By the time the leaves are shed, 

 spermogonia and ascocarp initials are produced coincidentally 

 in separate structures on the same superficial mycelium. Both 

 structures are dimidiate, with a flat cushion of fertile cells formed 

 beneath the shield. The spermogonia are ostiolate and shed 

 spermatia through the pore. Whether the spermatia function is 

 not known, and ascogenous hyphae have not been observed. 

 Each ascus arises individually and creates a loculus within the 



