DISCOMYCETES 



241 



An older, more commonly employed system of classification 

 considers the Discomycetes to be comprised of the Pezizales, 

 Helvellales, Helotiales, and Phacidiales. The Phacidiales includes 





Fig. 98. Diagram of the development of a gymnocarpous apothecium. 

 (After Corner.) The circle indicates the position of the ascogonium 

 within the apothecial initial. A. Branched hyphae surround the ascogo- 

 nium. B. Ascogenous hyphae arise from the ascogonium and are separated 

 by sterile hyphae. C. A layer of asci (hymenial layer) forms exposed at 

 the upper surface of the young apothecium. D. A fully formed apothe- 

 cium with poorly developed rim. 



those with leathery and carbonaceous ascomata, whereas the 

 Others are fleshy. The operculate genera are included in the 

 Pezizales and the Helvellales. There are approximately 20 genera 

 and 300 species of Helvellales, and 100 genera and 3300 species 

 of Pezizales. Among the larger genera are Helotium with 280 

 species, Humaria and Dasyscypha with 220 each, Mollisia with 



