178 



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. 







UlU^ \ 



( 



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7 



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lai^ 



Fig. 39. — Hydnum schiederinayeri. 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 



