278 CLASS ASCOMTCETEAE 



conidiophores. In Graphium similar conidia are produced but the conidio- 

 phores are united together in a tall dark-colored stalk (technically a 

 synnema). In most cases the conidia are embedded in slime as are the 

 ascospores and are distributed mainly by insects, which bore in the wood 

 or bark, to whose bodies the spores adhere. The dreaded "Dutch Elm 

 Disease" has for its perfect stage 0. ulmi (Buis.) Nannf., Graphium ulmi 

 Buis. being the conidial stage. This as well as several other species has 

 two sexual strains which must be brought into contact before perithecia 

 will appear. Dade (1928) found that this was also true of 0. paradoxum 

 (Dade) Nannf. This has for its conidial stage Thielaviopsis. (Fig. 90 G.) 



Richard and Olga Falck (1947) create another "class" of the "Asco- 

 mycetales," which they call "Class Haerangiomycetes." In this class they 

 place those species of Melanospora and Ceratostomeila (Ophiostoma) in 

 which the ascus does not possess a definite cell wall but merely a plasma 

 membrane or where the ascus wall is almost immediately dissolved after 

 its formation. In these fungi, therefore, the ascus does not exercise its 

 normal function of ascospore dispersion but these spores are carried out 

 through the ostiole in a mass of "mucus" and rest in a drop in the funnel- 

 like "haerangium" formed by filaments diverging from the edge of the 

 ostiole. In the ascus the spores are formed, eight in number, shaped like 

 the segments of an orange and arranged in a similar manner. This struc- 

 ture the authors call an "octophore." This "class" is considered to be an 

 evolutionary development from Sphaeriales in which definite, functional 

 asci occur. 



Family Cucurbit ariaceae. This family formerly included in this 

 order undoubtedly belongs in the Order Pseudosphaeriales under which 

 it is discussed. 



Family Lophiostomataceae. Except for the base which is partly 

 sunk in the substratum and the laterally compressed ostiolar papilla 

 this family differs very little from the Sphaeriaceae. The ostiole com- 

 pressed into a slit resembles somewhat that of the Hysteriales. This 

 resemblance is only superficial for the lateral compression is confined 

 mainly to the ostiole and ostiolar papilla in this family while in the Hys- 

 teriales the whole'spore fruit is laterally compressed. Lophiostoma is the 

 largest genus of the family. The fungi of this family are mostly saprophy- 

 tic on bark, wood, or dead herbaceous stems while only a few species 

 are possibly parasitic. Conidial stages are known for only a few forms. 

 (Fig. 91 A.") 



Family Amphisphaeriaoeae. In general appearance except for its 

 circular ostiole this resembles the preceding family, but the study of the 

 development and the inner structure of the perithecia indicate that it 

 probably may belong to the order Pseudosphaeriales. 



Usually placed next are the families with perithecia entirely sunken in 



