240 



CLASS ASCOMYCETEAE 



Fig. 85. Hysteriales, Family Hysteriaceae. (A, B) Hysterographium minutuni 

 Lohman. (A) Apothecia and pycnidia. (B) Ascus and paraphysis. (C) Hysterium 

 insideiis Schw., asexual stage {Septonema spilomeum Berk.). (D, E) Lophium mijtil- 

 inum (Pers.) Fr. (D) Asexual stage, Papulospora mytilina (Pers.) Lohman. (E) 

 Pycnidial stage. (After Lohman: Papers Mich. Acad. Sci., 17:229-288.) 



in a few species, usually with the conidiophores included in a pycnidium 

 or somewhat similar structure. Lohman (1933) has shown that some of 

 the conidial forms usually assigned to the genus Sporodesmium, of the 

 Fungi Imperfecti, are the conidial stages of several species of Hysteriales. 

 Besides this spore form other conidial stages observed by him represent 

 the genera Papulospora and Septonema of the Moniliales and various 

 forms of the Sphaei;opsidales. The details of sexual reproduction are 

 almost unknown in this group. The relationships within the order and 

 to other orders are still more or less problematic. Usually the more than 

 400 species are distributed among several families. Of these Nannfeldt 

 (1932) removes the genera assigned to the Hypodermataceae to the 

 Phacidiaceae, where they have been placed in this work. Some of the leaf 

 inhabiting fungi formerly ascribed to this order (e.g., the genus Parmu- 

 laria) are placed by the more recent students of the group in the Pseudo- 

 sphaeriales. This leaves as the only important family the Hysteriaceae. 

 Family Hysteriaceae. Apothecia external, black and carbonaceous, 

 single or united in a stroma. Most of the species of this family are sapro- 

 phytic on bark or decorticated twigs or branches. Hysterographium 

 fraxini (Pers. ex Fr.) de Not. is common on various species of ash (Frax- 

 inus). Its ascospores are dark-colored and divided by transverse and 

 longitudinal septa. The apothecia are boat-shaped. (Fig. 85.) 



