252 



Minnesota Plant Diseases. 



The fruiting body lives from year to year, adding new growths 

 of pores annually. 



The sulphur-fungus rot [Polyporus sulphureus (Bull.) Fr.]. 

 After a prolonged rainy season in spring or summer one often 



Fic. 123. — The fruiting body of the flattened pore-fungus (Fomes applanatus) ; on a 

 standing dead tree trunk. Original. 



finds, particularly on oak trees, large masses of a tough, fleshy 

 fungus, consisting of numerous shelves overlapping each other. 

 The shelves are yellow to bright red above, becoming yellowish- 

 white with age ; the lower surface of each shelf, where the pores 

 occur, is of a pure sulphur-yellow color from which the common 



