228 



Bulletin 193. 



occurs on living or dead trees. It is a " wound " parasite, entering 

 through broken branches, through wounds caused by impact of fall- 

 ing timber, or where the cambium lias been scorched by iire. The 

 fruit bodies are entirely white. AVhen old or dry they often take 

 on a pale yellowish tinge. They are shelving, the cap attached 

 directly to the tree, broad at the free end and tapering somewhat in a 

 wedge-shaped manner toward the base. They are rarely single, and 

 sometimes scattered over the trunk. They usually occur, several 



S5BP^ 



ar 



-r 





58. — Polyporus borealis, Hymenmni witJi sinuous pores. 



close together overlapping in an imbricated fashion, and joined at 

 the base in a common trunk at the exit from the tree. 



The fruit bodies are rather soft and spongy. They last only for 

 the season. They are 10 to 20 cm. (1 to 8 inches) long by 6 to 15 

 cm. broad. They form larger masses where several are joined. The 

 upper surface is rough with coarse tufts of mycelium giving it a 

 very shagg}^ or sodden appearance. The honey-combed surface is 

 below. The hymenium consists of quite regular ^^ores with rounded 



