272 THE ASCOMYCETES 



Dodge, B. O., "Methods of culture and the morphology of the archicarp in 

 certain species of the Ascobolaccac," Bull. Torrey Botan. Club, 39: 

 139-197, 1912. 



DowDiNG, E. S., "The sexuality of Ascobohts stercorarhis and the trans- 

 portation of the oidia bv^ mites and flies," Ami. Botan., ^5; 621-637, 1931. 



Gwynne-Vaughan, H. C. I., and H. S. Williamson, "The cytology and 

 development of Ascobolus incigjiificus,'" A?J7i. Botmiy, 46: 65y-670, 1932. 



Harper, R. A., "Sexual reproduction in Fyroneiiia confliiens and the 

 morphology of the ascocarp," Ann. Botany, i^; 321-400, 1900. 



Schweitzer, G., "Zur Entwickelungsgeschichte von Ascobolus strobilimis, 

 n.s.," Planta, 72:588-602, 1931. ^ 



Seaver, F. J., The North Ainerican cup-fimgi (Opercidates) , Supplemented 

 ed. 377 pp. Published by the author. New York, 1942. 



Tiiberales 



The Tuberales, commonlv called truffles, are tvpicallv sub- 

 terranean, although a few species are imperfectly buried or grow 

 quite near the surface among decaying leaves. At least some of 

 them grow only in association with certain species of trees, 

 especially oaks and beeches. It was this constant association with 

 trees, in fact, which led Frank long ago to postulate that truffles 

 may establish the symbiotic relationship which he designated as 

 mycorrhizal. Evidence of this preference for particular tree 

 species is contained in the report of Parks (1920) that in Cali- 

 fornia he unearthed ascocarps of 7 genera, including 1 1 species, 

 in an area 10 ft square beneath an oak tree, Qiierciis agrifolia. 



The gross appearance of fruit bodies of truffles would lead 

 the observer to suspect them of being Gastromycetes, among 

 which they were, in fact, placed by early investigators. The 

 ascocarps are globular structures varying in size from 0.5 cm to 

 about 8 cm. They are brownish in color, and their surface may 

 be smooth or warty. The rind or peridium is a compact, resistant 

 layer composed of thick-walled tissue. The interior consists of 

 elaborate folds or chambers lined with a palisade of asci, inter- 

 spersed with loose fungus tissue. 



The Tuberales comprise a relatively small assemblage, having 

 27 genera and approximately 200 species. Four species were de- 

 scribed in Persoon's Synopsis Alethodica Fiingonnn. Thirty 

 years later, with the appearance of Vittadini's classical Mono- 

 graphia Tiiberaceannn, the known forms increased to 13 genera 

 and 73 species. Massee (1909) lists 11 genera and 32 species as 



