1 78 PLANT DISEASES 



clavate on the margin, while on the under surface the 

 spines are awl-shaped, and bear the hymenium. A 

 wound-parasite on oak, beech, elm and birch. 



Fig. 39. Hydnum schiedermaycri. Entire fungus ; 

 about one-quarter nat. size. 



During decay the colour of the wood is grey, with a 

 tinge of yellow, alternating with pale brown stripes. The 

 ferment secreted by the mycelium causes the inner layers 



