MYCOLOGIA 



Vol. XI September, 1919 No. 5 



SOME DESCRIBED SPECIES OF PORIA 



William A. Murrill 



The brown and black species of this group have already been 

 treated in North American Flora and one genus, Xanthoporia, 

 was recently described in Mycologia. The resupinate polypores 

 are particularly difficult for several reasons. In the first place, 

 they lack the definite shape which is often a determining char- 

 acter in the pileate forms; they are, moreover, entirely destitute 

 of a " surface," with the various important characters which it 

 usually afifords ; and they are mostly small, the characters that 

 are present being necessarily on a small scale. 



As a rule, each individual specimen has to be examined with 

 the microscope, and, even then, the well-known variability in 

 microscopic characters often leaves one in doubt, in working 

 with original specimens in foreign herbaria, it is often impossible 

 to get satisfactory results because of the character of the work 

 required and the time it consumes. Accidental resupinate forms 

 among pileate species also give considerable trouble because of 

 their close resemblance to forms uniformly resupinate, and for 

 this reason a wide and accurate knowledge of pileate forms is 

 essential. 



The white and bright-colored resupinates are more difficult 

 than the rest because there are more species with fewer charac- 

 ters, more confusion with pileate forms, and less chance of 

 obtaining spore characters. Specimens found in the herbaria 

 are almost invariably without notes, as well as without good 

 spores, so that the preparation of adequate descriptions must be 

 [Mycologia for July (11 : 163-230) was issued August 30, 19x9.] 



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