THE SAC FUNGI (ASCOMYCETES) 



227 



organs of another ascomycete, Sclerotinia (Fig. 183). In case 

 of both Peziza and Sclerotinia, the cups are external indica- 

 tions of a much larger internal growth of the fungus. In 

 Sclerotinia, commonly called the brown rot of the stone fruits 

 (peach, plum, apricot, cherry), the infection of the host long 

 precedes the production of cups. Mycelial hyphse penetrate the 

 fruit or the flower and grow extensively in it, often extending 

 to the twig. After a period of such growth there appear upon 

 the surface of the fruit, which is now shriveling or decaying, 



FIG. 183. Brown rot (Sclerotinia) growing upon old plums 



At the right are some of the fruiting cups ; in the middle is a greatly magnified 



portion of the cup, showing the spore-bearing areas ; and at the left is one of the 



spore-bearing threads still more magnified. After Duggar 



many tufts of light-brown hyphse. Among these tufts are 

 conidiophores, upon which conidia are produced.. These con- 

 idia are scattered by wind, by contact with insects, etc., and, 

 alighting upon favorable growing places, produce new myce- 

 lial growths. It is thought possible that these conidial spores 

 may persist throughout the winter. Infected fruits may be- 

 come dried and shriveled, and hang upon the tree or fall to 

 the ground. When favorable growing conditions return in the 

 next season, or even in a later season, the brown cups are pro- 

 duced from the mass of mycelium in the old fruit. These cups 

 are composed of many hyphse closely pressed together. In the 

 tips of some of these hyphae in the bottom of the cups the spores 



