POLYPORACEAE 



341 



decay of standing timber. Hydniim septentrionale induces 

 heartwood rot of maples. 



Polyporaceae 



The Polyporaceae, or pore fungi, as treated in this book, com- 

 prise about 20 genera and perhaps 2000 species. They are of 

 enormous importance as the cause of disease of standing timber 



Lamellate 



Fig. 132. Structural characters employed in identification of polypores, 

 including: A to H, types of fruiting bodies, / to M, pore surfaces, N to P, 



setae, Q, paraphyses, R, cystidium. 



and decay of logs and lumber. Many American students have 

 devoted themselves to problems of the taxonomy and classifica- 

 tion of the polypores; among them are Murrill (1907-1908, 1910), 

 Ames (1913), Overholts (1914, 1915), Burt (1917), Baxter (1927, 

 1929, 1932, 1933, 1934), Shope (1931), Humphrey and Leus 

 (1931), and Lowe (1934). Similarly many mycologists in other 



