320 CLASS ASCOMYCETEAE 



laceae; and in some Hypocreales, it does not seem to him to be of sufficient 

 importance to warrant the erection of a separate family. He distributes 

 the genera examined by him among the Microthyriaceae, Polystomel- 

 laceae, Molhsiaceae, Myriangiales, etc. The presence of hyphopodia in 

 some genera would suggest relationship to Meliola or related genera. Miss 

 Doidge (1942) included the genus Englerulaster in the genus Asterina in 

 the Microthyriaceae. (Fig. 102 C.) 



Family Capnodiaceae. These are transferred by Arnaud (1925) to 

 the Sphaeriales but it seems best to follow Theissen and Sydow in retain- 

 ing them in the Erysiphales. It must be noted that the work of Miss 

 Fraser (1935) on the development of the ascocarp of Capnodium shows 

 that this starts as a stroma in which develops an archicarp with asco- 

 genous hyphae and asci. This would indicate that the relationship of this 

 genus lies with the Pseudosphaeriales. The investigations of Graff (1932) 

 on Meliola and of various authors on Erysiphaceae show that in those 

 fungi the structure is a true perithecium. Their relationship is probably 

 with the Sphaeriales. When further developmental studies are carried on 

 in other genera of the families tentatively placed in the Erysiphales a 

 better realization as to their true position may be obtained. The dark- 

 colored mycelium of the Capnodiaceae is usually superficial and in many 

 cases saprophytic on "honey dew," the sugary deposit forming on plant 

 parts from the droppings of aphids, scale insects, etc. This mycelium 

 sometimes forms a black papery layer that can be peeled off from the 

 underlying leaf. In a few genera hyphopodia are present. Miss Fraser 

 (1937) has made an extensive study of the physiology of the "sooty mold " 

 fungi, including their food requirements, and relations to temperature, 

 light, and to the presence of other fungi on the same leaf. The conidia are 

 borne in pycnidia of various shapes, sometimes elongated like a long 

 necked bottle. The external perithecial walls are formed of parallel, later- 

 ally adhering hyphae, not of polygonal cells as in the Erysiphaceae and 

 Meliolaceae. These component hyphae may be dematioid, i.e., monili- 

 form, or perisporioid, i.e., with parallel sides. In the same genus may be 

 found species with ostiolate perithecia and other species whose perithecia 

 lack ostioles. The perithecia may be sessile or more or less stalked, some- 

 times elongated like the pycnidia. The ascospores vary from colorless to 

 colored and from two- to many-celled. Theissen and Sydow recognize 25 

 or more genera and 50 or 60 species, mostly tropical or subtropical, but 

 some found in temperate regions. Capnodium salicinum Mont, occurs 

 upon willow {Salix) leaves and twigs in Europe. C. citri Berk. & Desm. 

 causes sooty mold on oranges, etc. wherever they are cultivated. A few 

 species of Limacinia occur on leaves of trees and shrubs in temperate re- 

 gions, even as far north as Germany and England. (Fig. 102 D.) 



