FUNGI 



147 



some that are important. All of them, at some period of 

 the life-history, produce spores in sacs, and the sacs are 

 usually contained in a spore- 

 fruit. The spore-fruit is of three 

 general kinds: (1) a hollow sphere, 

 completely enclosing the sacs; (2) 

 a flask-like structure with a small 

 open neck; and (3) a cup-like or 

 saucer-like structure which is 

 lined by a layer of sacs. 



The first kind of spore-fruit is 

 illustrated by the mildews just 

 described. It is of interest to 

 know that truffles are such 

 closed spore-fruits, having be- 

 come large and edible. The 

 truffle Fungi are saprophytic, 

 the mycelium being found espe- 

 cially in forests under decaying 

 leaves. The truffles of commerce 

 are obtained chiefly from France 

 and Italy. 



The sac Fungi with flask-like 

 spore-fruits are illustrated by 

 many forms growing on dead 

 wood or as parasites under the 

 bark of trees and shrubs, and 

 forming upon the surface of the 

 bark black, wart-like growths 

 that include the spore-fruits, in 

 plum- and cherry-trees produc- 

 ing the disease known as black 

 knot. An important member of 



this group is the fungus that produces the ergot of medi- 

 cine. It is parasitic upon the young heads of rye and 



FIG. 136. Head of rye attacked 

 by ergot fungus, conspicuous 

 growths replacing the grains of 

 rye. After TULASNE. 



