488 CLASS BASIDIOMYCETEAE 



species, is just as capable of causing rot when inoculated into wood blocks 

 as is the dicaryon mycelium. The production of oidia by the monocaryon 

 mycelia of Polyporaceae has been demonstrated by Vandendries (1936) 

 in Leptoporus adustus (Fr.) Quel. (Bjerkandera adusta (Fr.) Karst.). Such 

 oidia do not occur on the dicaryon mycelium of this species. This species 

 is quadripolar as are Leucoporus hrumalis (Fr.) Quel, and L. arcularius 

 (Batsch) Quel., neither of which produces any oidia. 



The number of species in this family is very uncertain. Several 

 thousand have been described but it is probable that very many of these 

 are synonymous. The opinions as to the validity of described species vary 

 greatly. Thus in Gaumann-Dodge, Comparative INIorphology of Fungi 

 (1928) the genus Polysticius is credited with nearly 1000 species while 

 Killermann (1928) in the second edition of Engler and Prantl, Die 

 Nattirlichen Pflanzenfamilien, admits only "some hundreds." The agree- 

 ment is still less as to generic limits. Killermann recognizes 16 genera in 

 the family limits adopted in this work, but Murrill, in North American 

 Flora (1907-1908) recognizes 78 genera for North America alone. Bon- 

 darzew and Singer (1941) have made a very complete and radical revision 

 of the genera of this family. They exclude 11 genera from the old family 

 limits but still retain 53 genera. Their basis for segregation and classifi- 

 cation of the genera is largely anatomical, so that the 11 old Friesian 

 genera are broken up into many sharply defined and not so unwieldy 

 ones. Singer (1944) adds one genus and gives further information as to 

 the systematic arrangement within the family. William Bridge Cooke 

 (1940) recognizes 46 genera from North America (most of them also 

 occurring in Europe) and 19 more from the Tropics and the Southern 

 Hemisphere. The anatomical studies by Miss Ames (1913) contributed 

 considerably to the work leading to the further subdivision of the older 

 genera. 



In the following discussion of the more important genera of the family 

 the attempt has been made to give the modern names of the genera and 

 species mentioned as well as the names that are to be found in the older 

 standard works. 



The genus Poria was in its customary limits used for the completely 

 resupinate members of this family, regardless of the color and consistency 

 of the trama, color of the spores, etc. Studies by Baxter (1929-1949) and 

 others have shown that many species closely related to other genera may 

 develop in a resupinate manner and thus be assigned to the genus Poria, 

 which as a consequence became a catchall for unrelated forms which 

 agreed only in their resupinate habits. Nevertheless, it seems that there 

 remains a body of species that are more or less closely related and which 

 properly may be given this name. Poria produces resupinate spore fruits 

 which adhere to the substratum and consist mainly of a thin layer of 



