Minnesota Plant Diseases. 251 



for whole forests have been reported killed by it. It is not 

 uncommon in this state, particularly on oaks. 



Tinder-fungus rot [Ponies fomcntarius (L.) Fr.]. This fun- 

 gus is similar in its habits and characters to Fomes igniarius. 

 Like the latter it is a true pore fungus. The pores on the lower 

 surface are at first whitish, becoming grey-brown with age. 

 New layers of pores are laid on each year as can be seen by the 

 zoned character of the shelf. The upper surface of the fruiting 

 body becomes covered with a very hard coat of greyish color. 

 Internally the fruiting body consists of a felted, softer material 

 above and a tinder mass, through which the long pores, built 

 up in zones, extend to the openings on the lower surface. The 

 age of the fungus can be approximately figured from the num- 

 ber of zones in the fruiting body. It may be of considerable 

 age and of such a size as to be useful for tinder. Specimens 

 havje been observed which were almost a century old. 



The tinder fungus is, like the false tinder-fungus, a danger- 

 ous parasite and gains entrance through the stem in a similar 

 manner. The growing zone beneath the bark, chiefly upward 

 and downward from the point of entrance, is killed and the 

 wood beneath undergoes rotting. \Yood attacked by the tinder 

 fungus becomes yellowish. Radial patches of the white felted 

 mycelium may often occur in such wood. 



The fruiting bodies of the tinder fungus were formerly ex- 

 tensively used in Europe for tinder and also in the manufacture 

 of caps, gloves, etc. The tinder has also the property of 

 staunching blood-Mow from cuts and has been used for that 

 purpose. 



The flattened pore-fungus rot [I : <>mcs a^hinatus (P.} 

 ll'iiHr.]. This is a very common pore fungus on old stumps 

 and fallen logs, less commonly found growing from wounds on 

 living trees. The hard-crusted shelves vary greatly in size, 

 some of the largest attaining a width of several feet. The shelf 

 is woody and the upper surface greyish to brown. The latter 

 is often covered with a fine dust of accessory spores of a dark 

 reddish brown color. The upper surface is covered with a hard 

 crust and the interior of the shelf is of a softer fibrous texture 

 and dark brown in color. The pores are very small and cover 

 the under surface, which is pure white, when newly formed. 



