BASIDIOMYCETES. 



165 



fruit-bodies, with zones of various colours on the upper side ; it is one of the 

 most frequent species on tree-stems. P. frondosus grows on soil in woods, and 

 consists of numerous aggregated fruit-bodies, which become very large and 

 fleshy. This species is edible. P. perennis also grows on the soil in woods ; 

 it is very leathery, with central stalk, and has concentric zones on the upper 

 surface of the fruit-body. P. vaporarius destroys the wood of living Pines 

 (Pinus silvestris) and 

 Firs (Picea excelsa), 

 causing it to become 

 red-brown ; in timber 

 this Fungus causes 

 "red-strip" followed 



by a "dry-rot." P. *JHn^g&%@jffi&mi6^^^& t 

 squamosus destroys 

 many Walnut - trees, 

 and is also very de- 

 structive to Limes and 

 Elms. P. fulvus causes 

 a "white -rot" in Abies 

 alba. 



Heterobasidion an- 

 nosum (Polyporus an- 

 nosus, Trametes radici- 

 perda, Fig, 169) is 

 characterized by its 

 Aspergillus-like coni- 

 diophores. It is a 

 parasite on the Pine, 

 Fir, Birch, Beech, etc., 



FIG. 168. Section of stem of a Beech attacked by P. fomen- 

 tarius : anon-attacked pares of the stem; b the furrows where 

 the mycelium has reached the bark, and where the thick 

 mycelium-strands reach the exterior ( Jth of the nat. size). 



FIG. 169. Base of a Fir-tree, with a number 

 of fruit-bodies of Heterubnsidion annosum just 

 beneath the surface of the soil, indicated by 

 the dotted line (ith nat. size). 



FIG. 170. A fully developed fruit- 

 body of Polyporus pini (Trametes 

 pini), lateral view (nat. size). 



