POLVPORUS. 



445 



surface, and a smooth yellowish hymenial surface. They are 

 large and flat, the thickest part being at their insertion 

 (Fig. 277). Several frequently occur on the same stem, especially 

 if wounds or frost injuries are present. The spores are brown 

 and roundish. Conidia are said, by Schroeter, to be formed on 

 the upper surface of the sporophores. 



This species is a deadly enemy of fruit-trees, especially 

 apple. In the vicinity of Munich the sporophores are common 

 on ash. Schroeter gives elm and plane as hosts, and Prillieux 



Fig. 277. — Polyporus hispidTiS, Longitudinal section through a living stem of 

 Ash, and a sporophore of F. hispidus. The stem shows symptoms of wood- 

 destruction, in that it becomes brown and has short white longitudinal and 

 radial stripes, (v. Tubeuf phot.) 



and Delacroix state the fungus' to be very dangerous to the 

 mulberry in France. 



It causes^ brown discoloration of the wood accompanied by 

 characteristic short white lines in both radial and vertical 

 directions, so that the wood becomes marked out in squares. 



Polyporus (Poria) laevigatus Fr.^ Sporophores dark-brown 



1 Prillieux (Bnllet. de la Soc. mycolog. de France, ix., 1893), gives details of 

 the destruction of the wood. 

 ^Mayr, Botan. Oentralblatt, xix., 1884. 



