DISEASES OF BOOTS, ETC. 45 



white like chalk. The pores on the underside may wear 

 off with age. The fruiting bodies often grow on large 

 open wounds, forming large irregular, perpendicular 

 rows. Two or more fruiting bodies may appear on the 

 same tree at different heights. Altogether the fruiting 

 bodies are not common. 



SULPHUR FUNGUS. 



The sulphur fungus (Polyporus sulphureus, PI. IX) 

 often attacks living and dead mature and overmature 

 oaks, chinquapin, and red fir, but is found also on 

 Douglas and white fir, and yellow and Jeffrey pine. It 

 is very common and exceedingly destructive. The an- 

 nual fruiting bodies appear in clusters of large, rather 

 flat, yellow shelves. The upper side of the fruiting 

 body is smooth and bright yellow, sometimes light brick 

 color. The smooth underside is brilliant sulphur yel- 

 low, with small pores. The cheesy, juicy interior is yel- 

 low. During summer and fall the fruiting bodies dry 

 up, and turn either a dirty yellow, or more often a 

 chalky white, and become at the same time brittle. 

 They can easily be distinguished from those of Fomes 

 laricis, however, by their flat-shaped growth in clusters, 

 and absence of bitter taste. The fungus causes a red 

 heartrot, with very broad and thick white felts of 

 mycelium (PI. X), often forming a white star on a 

 cross section in the center of limbs and younger trees. 

 The sulphur fungus is the most destructive enemy of 

 red fir. 



