294 GENERAL MORPHOLOGY OF PLANTS 



rotten and dead wood, leaves, etc. Many of these belong to the 

 old genus Peziza. The asci are crowded over the upper surface 

 of the cup, and are surrounded below and on the sides by the 

 sterile tissue of the fruit body (or ascoma). A few are parasitic. 

 One of the most injurious (Sclerotinia fmctigena) causes the 

 common brown rot of cherries, plums, peaches, and sometimes 

 of apples also. The asexual stage (Monilia) causes the rot of 

 the fruit. The conidia are borne in long chains. The rotted 



Fig. 242. 



Monilia fructigena, showing chains of conidia, also showing how the conidia separate from 

 each other in the chains. Two conidia at the right germinating. (After Woronin.) 



peaches and plums become dried and "mummified," and many 

 hang on the trees for a large part of the winter and the following 

 summer. They fall to the ground, and after passing another 

 winter, half or completely buried in the ground, the dormant 

 mycelium in the " mummies" develops the cups, which are 

 supported on long stalks to lift them above the ground. 



444. The morels. These are large fleshy fungi with a stout 

 stalk bearing a large head which is covered with numerous 



