THE SECTION MICROPORUS OF POLYSTICTUS. 



The subject of the Polyporoids is so extensive, there being about 

 two thousand alleged species, that one can not hope to do much with 

 it as a whole without first breaking it up into sections and studying 

 them one at a time. 



The section Microporus is a very natural section, although it runs 

 through thicker forms into Polyporus. The characters of the section 

 are the thin, rigid pileus, the minute pores in a very thin layer, and 

 the color. It is usually stipitate, but the stipe varies much in length and 

 insertion. In some specimens it is mesopodal, and sometimes in others 

 of the same collection it is pleuropodal or lateral. In some specimens 

 it is black, and in others yellow. The color of the pores is usually 

 white when fresh, though sometimes, I think, yellowish, and in the 

 herbarium specimens they usually change to isabelline or wood color. 

 The surface is either smooth, minutely velvety, or zoned with pubescent 

 zones. The color of the pileus is reddish brown, bay, or sienna brown. 

 It varies in degree to almost black in depth, but the "ground color'' 

 is always the same. 



The "species" are extremely variable and run into each other in a most 

 puzzling manner. They could he called one species, which would be the easiest 

 way to dispose of the matter. The objection to this would be that the extreme 

 forms vary so much that it does not seem possible to include all in one species. 

 And these different forms do have a value, for in the same collection the 

 specimens are usually much alike and there is undoubtedly a geographical sig- 

 nificance in these forms. 



The species are distributed in Saccardo through two sections, "Sacri," a 

 mesopodal section, and "Discipedes," a lateral stemmed section. This arrange- 

 ment is quite embarrassing from the fact that in the same collection are speci- 

 mens that belong to both sections. At the same time the insertion of the stem 

 is the best leading character to divide the species. Most collections and un- 

 doubtedly most localities show a decided preponderance of specimens in favor 

 of one or the other series. 



We believe that a few definite ideas should be associated with each "species, ' 

 and may be expressed in a very few words. Under this plan most of the 

 specimens will readily fall into some "species" though no plan can be devised 

 that will cover every case. Even in the same collection individual specimens 

 may deviate. However, collections should be classed by their prevalent char- 

 acters and not from any one specimen. There are two extreme forms: Poly- 

 stictus xanthopus with a central yellow stem and glabrous pileus, and Poly- 

 stictus flabelliformis with a lateral, black stem and pubescent, zoned pileus. 

 All the species can be arranged between these two extremes. 



Key to the species. 

 Stipe mesopodal 



Stipe smooth, yellowish. Pileus glabrous xanthopus 



Stipe black. Pileus, soft -velvety concmnus 



Stipe black. Pileus with pubescent zones Holsti 



Stipe black. Pileus densely pubescent pseudo-pere 



Stipe lateral 



Stipe concolorous or black. Pileus glabrous ami 



Same character but a thicker, more robust plant 



American form (probably the same) porphyntis 



Stipe black. Pileus dark, almost black; smooth. Pores 



F dark carneo-mger 



Stipe black. Pileus with pubescent zones . . 

 49 



