TUBERALES 



51 



LITERATURE. 



Thaxter. On some North American species of Laboulbeni- 

 aceae. Proc. Amer. Acad. Arts and Sci. 26 : 5-14. 1890. 



■ Supplementary note on North American Laboulbeni- 



aceae. Ibid. 261-270. 1891. 



Further additions to the North American species of 



Laboulbeniaceae. Ibid. 27 : 29-45. 1892. 



New species of Laboulbeniaceae from various localities. 



Ibid. 28 : 156-188. 1893 



New genera and species of Laboulbeniaceae with a 



synopsis of the known species. Ibid. 29 : 92-1 11, 1894. 



Notes on Laboulbeniaceae, with descriptions of new 



species. Ibid. 30: 467-481. 1895. 



All the above are short ])apers, simply preliminary to the next 

 elaborate monograph. 



Contribution towards a Monograph of the Laboulbeni- 

 aceae. Mem. Amer. Acad. 12 : 187-429. PI. 1-26. 1896. 



Order 10. TUBERALES. 



The members of this order are subterranean fungi resembling 

 tubers. Some of the species known as truffles are highly prized 

 for food and command high prices in European markets, two 

 average sized canned truffles often retailing for three francs. The 

 truffle varies from the size of an acorn to the size of a fist and 

 has a warty appearance on the outside. The asci are formed on 

 the interior of the fungus. Little is known of the method of 

 spore dissemination. The edible species have not yet been found 

 in America, but several smaller and unimportant forms have oc- 

 casionally been found. The truffles are not to be confounded 

 with the various forms of subterranean puff-balls which are com- 

 paratively common in the Southern States, nor with certain of 

 the subterranean Aspergillales which resemble them even more 

 closely since they produce their spores in asci. In Southern 

 Europe the true truffles are hunted either by dogs or pigs trained 

 for the purpose. 



The two families of Tuberales are distinguished as follows : 



Ascocarps formed of several labyrinthine passages opening outward at 

 maturity. Tuberaceae. 



Ascocarps with a single or several closed cavities not opening outward at 

 maturity. Balsamiaceae. 



