ORDER PEZIZALES: SUBORDER OPERCULATAE 227 



same variety and the same is true for the Kieffer pear, but these two 

 varieties are usually fertile to each other's pollen. It is perhaps more 

 comparable still to the dimorphic species of Primula studied by Darwin 

 (1889), in which the seeds of a capsule will produce about equal numbers 

 of the two types of primrose plants, those with flowers possessing a long 

 style and low-placed stamens and those whose flowers have short styles 

 and stamens high in the corolla tube. Each strain is relatively sterile with 

 pollen from plants of its own type but fertile with pollen from plants of 

 the other type. Whether the condition in Ascoholus magnificus Dodge is 

 like the foregoing, i.e., a case of self-sterility, or is true heterothallism 

 (a real difference in sex) remains to be discovered by further study. 



The " Discomycetes " were classified by the earlier investigators 

 Persoon (1801) and Fries (1822), largely on the basis of external charac- 

 ters. Later the ascus and ascospore characters were also taken into con- 

 sideration. The internal structure of the apothecium proved to be of great 

 importance. Durand (1900) used this as a basis for a tentative classifi- 

 cation. Nannfeldt (1932) has used these features in his extensive writings 

 on this group. Boudier (1907) pointed out that the mode of dehiscence of 

 the ascus, whether by a lid or by a pore, i.e., operculate or inoperculate, is 

 of great diagnostic value. Seaver (1928) in his volume on the Operculate 

 Cup-fungi recognized only two families in this suborder in place of a 

 larger number recognized by Schroeter and Lindau (1896) in Engler and 

 Prantl. 



Order Pezizales : Suborder Operculatae. Family Pezizaceae. Apo- 

 thecia flat, convex, or concave or cup-like, sessile, or short stalked, rarely 

 long stalked, and then the hymenium concave or at most flat. Apothecium 

 pseudoparenchymatous throughout, with few exceptions. Typical repre- 

 sentative genera in this family are: Ascoholus, growing on animal excre- 

 ment or on soil, with mature asci much protruding and with mature 

 spores violet in color. The apothecia vary, according to species and 

 environment, from less than 1 mm. up to nearly 3 cm. in diameter. In 

 A. immersus Fr. the ascospores may attain a size of 50 to 75 ju in length 

 by 20 to 35 /i in thickness, almost the largest ascospores known. Pyronema, 

 grows on soil, especially after a fire or after steaming. The apothecia are 

 1 to 2 mm. in diameter and the convex hymenium is practically naked 

 from the first. The ascospores are hyaline. Humarina {Humaria Sacc.) 

 is less than 1 mm. to 1 cm. in diameter, growing on the ground, forming 

 white or bright-colored, mostly disk-shaped apothecia, with hyaline 

 ascospores, differing from Ascophanus only in that the latter grows on 

 dung. Patella forms disk-shaped apothecia up to 1 cm. wide, and with 

 the outside clothed with hairs, at least at the edge. P. scutellata (L.) 

 Morgan {Lachnea scutellata (L.) Gill.) forms its brilliant red disks with 

 a fringe of dark hairs, on rotten wood and is strikingly beautiful. Plectania 



