238 



CLASS ASCOMYCETEAE 



Fig. 84. Tuberales, Family Tuberaceae. (A) Tuber uestivum Vitt., external \dew. 

 (B) Tuber rufum Pico, section through ascocarp. (C) Enlarged view of a portion of 

 the ascocarp, the ascospores with spiny surface. (D) T. ynagnatum Pico, ascus showing 

 ascospores with alveolate marking. (E) Genea hispidula Berk, vertical section through 

 ascocarp, showing the single cavity and opening. (After Tulasne, in Engler and 

 Prantl: Die Natlirlichen Pflanzenfamilien , Leipzig, W. Engelmann.) 



Perhaps the simplest structure in the order, according to Miss Gilkey 

 (1939), is that exhibited by some species of Hydnocystis. The hypogeous 

 spore fruit is subspherical, with an opening which is usually partly blocked 

 by hairs. The single large cavity is lined by an even hymenium made up 

 of cylindrical, 8-spored asci. The paraphyses are of about the same length 

 as these and do not form an cpithecium above them. Except for its per- 

 manently hypogeous habit this might well be placed in the Pezizales, a 

 position, in fact, to which Fischer (1938) assigned it. In Genea the main 

 cavity may have even walls or may be thrown into folds which much 

 increase the hymenial surface. The paraphyses grow out beyond the asci 



