172 PLANT DISEASES 



causing rot and death of the plant affected. It also occurs 

 on Lupines and Clover. 



Hypochnus so/ani, Prill, and Del. Forming greyish-white 

 patches on the lower parts of living potato stems, but doing 

 no appreciable damage. 



Cortidum comedens, Fries. This species is stated by 

 Rostrup to be a wound-parasite on the younger branches 

 of the oak. The fungus originates below the bark, which 

 eventually becomes torn and recurved, exposing the 

 hymenium, which is at first purplish, becoming almost 

 white; slightly viscid when moist. Not uncommon as a 

 saprophyte on fallen branches, especially hazel. 



PARTRIDGE WOOD 



(Stereum frustulosum, Fries.) . 



This fungus is sometimes a saprophyte, at others a 

 parasite, attacking various forest trees, but especially oak. 

 It differs from Stereum hirsutum in having no portion free 

 from the wood on which it is growing, its entire substance 

 forming a thickish, much cracked, very hard crust, firmly 

 attached to the wood. The fungus is perennial, forming 

 a new hymenium or spore-bearing surface each year, on 

 the surface of the hymenium of the previous year. Hence 

 the fungus continues to increase in thickness, and on 

 section presents a distinctly stratified appearance, a 

 character by which it is readily distinguished from 

 various other fungi presenting a similar superficial appear- 

 ance. The surface of the fungus is cinnamon colour when 

 in active growth, becoming greyish and minutely primrose 



