POLYPORUS 381 



pileus soft, rugged, becoming smooth, rusty, then dingy 

 brown, margin often exuding drops of water, which leave 

 depression when they dry up ; flesh rusty, fibrous, somewhat 

 zoned; tubes 1-2 in. long, thin, soft, rusty, pores small, 

 round. Spores colourless, elliptical, 5x3^. 



Often imbricated, smell somewhat acid, annual but persist- 

 ing through the winter. 



Polyporus salignus (Fries.). This species is often met with 

 on decaying willows, but its connection with the death of the 

 tree has not been determined. 



Tufted or imbricated. Pilei 2-4 in. across, rather thick, white, 

 slightly downy, grooved near the thick, more or less lobed 

 margin ; tubes elongated, pores tortuous, white. Inodorous. 



Polyporus borealis (Fries.). This fungus is rare in this 

 country, but Hartig says that it is the most frequent cause of 

 decomposition of the spruce in the Bavarian Alps and in the 

 spruce woods near Munich. Infection takes place above 

 ground. The colour of the wood is but slightly changed 

 during decomposition, it becomes brownish-yellow, and a 

 series of horizontally arranged holes, filled with white mycel- 

 ium, appear in vertical rows in the spring wood. Hartig was 

 not able to determine why these holes are only formed at 

 definite distances from each other. 



Sporophore bracket-shaped, usually imbricated, 2-3 in. 

 across, attached by a broad base, or narrowed behind into a 

 short more or less distinct stem, pileus whitish, often more or 

 less radially wrinkled, rather hairy; tubes 2-3 lines long, 

 pores unequal, wavy, dissepiments torn; spores colourless, 

 subglobose, 4 p diam. 



Inodorous when fresh, with a slight anise odour when dry. 

 Usually imbricated, the pilei growing into each other. Often 

 also met with on dead stumps of pine-trees. 



Polyporus spumeus (Fries.). On both living and dead 

 trunks of various kinds of trees. 



Whitish, 2-4 in. across, fleshy, spongy, pulvinate, gibbous, 

 rugose and hispid, margin incurved, base stem-like, flesh-zoned 

 towards the margin ; tubes short, pores minute, rounded. 



The fungus oozes out of the bark in a very soft mass, 

 which hardens in a day. 



. Polyporus destructor (Fries.). This fungus often occurs on 

 worked wood, more especially in damp places. The wood 

 is softened and destroyed in a similar manner as when 

 attacked by dry rot. 



