POLYPOREAE 349 



PoLYPOREAE. In PoHa are placed all fleshy, leathery, or woody 

 strictly resupinate forms having true pores. In a sense it is a 

 form genus, since normally shelving species may at times be 

 resupinate. The hymenium continues to develop centrifugally, 

 ne^^' pores being formed in the zone near the margin. Baxter 

 (1927, 1929, 1932, 1933, 1934) has devoted himself to the diffi- 

 cult problem of classification of this genus. All species may 



Fig. 133. Daedalea quercma, lower surface of fructification. 



cause decay of timber, some being especially destructive to beams, 

 floors, mine* props, and lumber piled in yards. Notable among 

 these fungi are P. vapor aria and P. incrassata [Humphrey 

 (1923)]. 



Polyporus includes a large number of species of pore fungi 

 having shelving or stalked fructifications that may be fleshy when 

 young but become hardened, leathery, or corky at maturity. The 

 pore layer is usually quite different in texture and color from 

 the remainder of the pileus. As thus delimited, Polyporus may 

 well include several generic types. 



Polyporus versicolor and P. pargamemis are perhaps the most 

 commonly encountered members of this genus. They cause de- 

 cay of many species of deciduous woody plants, just as P. abieti- 

 niis does of coniferous species. Polyporus sidphtireus, occurring 



