[From the Bulletin of the Torkey Botanical Club, 32 : 469-493. 1905,] 



The Polyporaceae of North America— XII. A synopsis of the white 

 and bright-colored pileate species 



William Alphonso Murrill 



A synopsis of species with brown context was given in article 

 XI of this series. The present paper deals with the genera and 

 the principal described species having a white or bright-colored 

 context and a distinct pileus. The species of certain genera are 

 so numerous that they must form the subject of a separate article. 



Subfamily i. POLYPOREAE 



It is not always possible to draw a distinct line of cleavage in 

 this group. Microporclhis, for example, has sessile forms which 

 are thin and multizonate ; Puualia, while usually brown, has some 

 nearly white variations, and Poly poms arcularius, Polyporus Polyp- 

 orits and Polyporus caudicinus have tubes very similar to those of 

 Hexagona. 



In distinguishing the subfamilies, also, certain species of Pomes 

 are annual at times, while normally annual plants may assume a 

 perennial appearance under favorable conditions. Poroid forms 

 of Agaricus are always liable to confuse the beginner. The classifi- 

 cation here adopted is acknowledged to be imperfect and artificial, 

 but it is hoped that it will lead to something better when our 

 knowledge of the plants treated is more complete. 



Synopsis of the Polyporeae with white context 



Hymenophore sessile. 



Tubes hexagonal, arranged in radiating rows; context thin. I. Hexagona. 

 Tubes alveolar ; context thin, dry, surface zonate. 2. Favolus. 



Tubes mostly shallow, marginal and obsolete ; hymenium hyd- 



noid or irpiciform at a very early stage. 3. Irpiciporits. 



Tubes normally poroid, sometimes irpiciform from the rupture 

 of the dissepiments at maturity. 



Hymenium at length separating smoothly from the context. 4. Piptoporus. 

 Hymenium not separating as above. 



Pileus very soft, spongy and elastic throughout. 



Hymenophore of immense size ; tubes small, 



fragile when dry. 5' Dendrophagus. 



Hymenophore small ; tubes large, not fragile. 6. Spongiporus. 



469 



