SPHAERIALES 267 



imperfect form, there occur erect, single, generally branched conidio- 

 phores which cut off ovoid conidia at their ends (Fig. 177, 6). They may 

 come together into columnar coremia, whereby they are oriented with 

 bilateral symmetry and abjoint conidia only on the inner side (Fig. 177, 

 7). With sufficient nourishment, these coremia differentiate to pycnia 

 in which the formation from individual hyphae is still more marked (Fig. 

 177, 8) and hence have been called hyphal pycnia; besides the tissue, 

 pycnia are formed (Fig. 177, 1 to 5) with true paraplectenchymatic walls 

 (Zopf, 1878). The perithecia, like the stipitate pycnia (Fig. 177, 8), arise 

 on a black, occasionally branched columnar foot, and show a structure 

 similar to that given in Fig. 176, 1 and 2 for Limacinia spongiosa and 

 Teichospora meridionalis. 



In spite of their frequency, all these epiphytic Amphisphaeriaceae 

 are known neither culturally nor phylogenetically. It is only certain 

 that in a species of Teichospora and one of Teichosporella, and in Pleo- 

 sphaeria Citri, the perithecia arise, as in Sporormia intermedia, by the 

 division of a single hypha in three planes (Nichols, 1896; Arnaud, 1910). 



The completely submersed Sphaeriales include most of the group 

 and occur in thousands of tiny, generally very monotonous species on 

 leaves, roots, etc. There are two families without stromata, the Myco- 

 sphaerellaceae (with asci not thickened at the tip) and the Gnomoniaceae 

 (with asci thickened at the tip and opening by a pore). 



Mycosphaerellaceae. — Among this family are also reckoned the earlier 

 " Pleosporaceae" except those belonging to the Pseudosphaeriaceae, as 

 Pleospora itself; this union of the Pleosporaceae and Mycosphaerellaceae 

 seems justified since the presence or absence of paraphyses is hardly 

 sufficient to separate families. 



This family has a special significance in its relationship to the Myri- 

 angiales; thus they have (in the old concept including the Pleosporaceae) 

 supplied the main group of the Pseudosphaeriaceae; similarly Didymella 

 and Leptosphaeria, which were discussed at the close of the Myriangiales, 

 earlier belonged to the Mycosphaerellaceae. The continuity of the 

 Pseudosphaeriaceae and Mycosphaerellaceae is secured through Myco- 

 sphaerella of the Mycosphaerellaceae which, through various transitional 

 forms, are continuous with Leptosphaeria and Didymella; thus in some 

 species of Mycosphaerella we find a scant, hyaline, insignificant peri- 

 thecial stroma, while other species possess true perithecia of the 

 Sphaeriales. 



Mycosphaerella, with over 1,000 species parasitic on all sorts of plant 

 substrates, generally forms its fructifications after wintering over under 

 the epidermis of dead and rotting tissue. According to the type of its 

 imperfect forms, it may be divided into several sections: Septorisphaerella 

 with Septoria, or Phleospora as imperfect forms, Ramularisphaerella with 

 Ramularia conidia and Cercosphaerella with Cercospora (Klebahn, 1918). 



