110 MURRILL : POLYPORACEAE OF NoRTH AMERICA 



8. Tubes long, over 0.5 cm, each season, walls thin, pores large, 3 to a mm. 9. 

 Tubes very short, 0.1-0.5 cm. long each season, walls equalling tubes in thick- 

 ness, pores small, 5 to a mm., spores globose, 4-5 Z^, cystidia none; growing 

 abundantly on Robinia. 6. P. Robiyiiae. 



9. Spores globose, 3-4// in diameter, cystidia present ; pileus blackish, very rimose, 



hymenium convex, margin truncate, at length hoary. 7. P. praerimosus. 



Spores ellipsoidal, 7 X 9i«) cystidia none ; pileus dark brown, hymenium concave, 



margin not hoary. 8. P. Underwoodii. 



10. Older pores visible in projecting annual layers, tubes 3-4 to a mm., thin-walled; 



pileus deeply furrowed, not rimose. 9. P. juniperinus. 



Older pores not externally visible, tubes 1-2 to a mm., thicker walled ; surface 



very rimose. 10. P. Earlei. 



11. Spores hyaline. 12. 

 Spores yellowish brown. 15- 



12. Cystidia abundant, pointed, dark brown; pileus thin, woody, rigid, tubes short, 



5 to a mm. II. P- conchatui. 



Cystidia none. 13- 



13. Context thick, woody, honey-yellow, surface encrusted, margin blunt. 



12. P. Haematoxyli. 

 Context thin, punky, darker brown, surface without a crust, margin sharp. I4. 



14. Pileus 10-25 c'l^- broad, covered with narrow shallow furrows, margin undulate 



or lobed, pores minute, 8-9 to a mm. 13. P. Langloisii. 



Pileus smaller, deeply sulcate, pores larger, 6 to a mm. ; growing on species of 



Ribes, very rarely on other shrubs. 14- P- Ribis. 



15. Dissepiments thick, hymenium concolorous with context. 16. 

 Dissepiments thin, hymenium darker than context. . 17. 



16. Pileus very rimose, cystidia present ; tubes fulvous, 7 to a mm., spores globose, 



3.5-5 II, cystidia 17-35/^. 15- P- Yticataneusis. 



Pileus scarcely rimose, encrusted, becoming smooth, cystidia absent ; margin 



undulate, tubes 8 to a mm., spores globose. 16. P. sefiex. 



17. Pileus hard and heavy, surface sulcate, brown, clothed with lime-white hair, 



spores 3.5//, spines 40-60 /z. 17. P. Hnteus. 



Upper layers of pileus dead, projecting 1-2 cm. beyond the lower, tube strata 



separated by thin layers of context, tubes 7 to a mm., spores 5-7 ,«, cystidia 



absent. 18. P. Jamaicensis. 



I. Pyropolyporus igniarius (L.) 



Boletus igniarius L. Sp. PI. 1176. 1753; Tourn. Inst, i: 

 562. pi. 330./. A. 1719. 



Polyporus igniarius Fries, Syst. i : 375. 1821. 



Fomes igniarius Gill. Champ. Fr. i : 687. 1878 ; //. 156. 



Phellinus iccniarius Quel. Ench. 172. 1886. 



