1 86 



PLANT DISEASES 



it also occurs on the elm (Ulmus campestris\ and on various 

 fruit trees, etc. The sporophore resembles a horse's hoof 

 or an inverted bracket, and varies from three to seven 

 inches across, or sometimes even more. The upper, convex, 



/itt*i& r r, i 



- . ii 



Fig. 42. Fomes fowentarius. Entire fungus with a 

 portion cut out to show the stratified pores, about one- 

 quarter nat. size. 



sterile surface is dingy brown, and marked with concentric 

 ridges ; when in full vigour the entire upper surface is 

 covered with a brown powder resembling snuff, a character 

 by which this fungus can be distinguished from allied 

 species. The edge is white at first, but finally becomes 

 dark-coloured like the rest. The hymenium, situated on 



