Murrill: Poi.vporackak of North America 31 



7. Tubes decurrent, very short, entire, pileus dark purple, ornamented here and there 



with paler radiating lines, surface finely toinentose, becoming glabrous. 



5. P. dihaphus. 



Tubes not decidedly decurrent, denticulate when mature, pileus yellowish to smoky 

 black, villose, at length glabrous, spores oblong, curved, 6X2//. 



6. P. Polyportts. 



8. Sporophore goblet-shaped, pileus less than 3 cm. broad, shallowly depressed at the 



center, stipe long, striate, expanding into the pileus. 7. P. Tuba. 



Sporophore trumpet-shaped, pileus '^-lo cm. broad, deeply infundibuliforni, stipe 



3 cm. long, pallid, pulverulent. 8. /'. cralcrellus. 



Sporophore not as above. 9. 



9. Pileus minute, 2 mm. in diameter, umbilicate, margin involute, pores alveolar. 



9. P. Aciiu/a. 



Pileus large, 10 cm. or more in diameter, umbrinous, stipe short, thick, hispid, 



pores at length sinuous, dissepiments dentate. 10. P. discoidens. 



Pileus of medium size, 2-5 cm. in diameter. 10. 



10. Context whitish or brownish in color, extremely thin. II. 

 Context golden-yellow, not extremely thin, tubes remote from the stipe. 



II. /'. phaeoxanthus. 



11. Pileus brown, polished, context light brown, tubes decurrent. 12. P. Cohwthiensis. 

 Pileus white or pallid, more or less translucent, context white, tubes adnate, ex- 

 ceedingly minute, 8 to a mm. 13. P. ohohis. 



12. Tubes alveolar. 1 3. 

 Tubes not alveolar. 1 5. 



13. Margin of pileus finely hispid, broadly sterile below, surface ochraceous, radiate- 



striate, stipe brown, pulverulent. 14. P. aemulans. 



Margin of pileus strigose, fertile below. 14. 



14. Pileus very thin, smooth, pellucid, fragile, stipe thicker below, setulose. 



15- P- arculariellus. 



Pileus not very thin, fuscous-squamulose to glabrous, stipe equal, grooved, squam- 



ulose, grayish-fuscous. 16. P. arcii/arius. 



15. Tubes fairly regular, stipe slender, not polished, plants rather delicate, cilia vari- 



able in form and persistence. 16. 



Tubes very irregular, stipe usually thick and polished, pileus tough, umbilicate, 

 yellowish-white with brown marginal band, cilia short, fugacious. 



17. P. variiporus. 



16. Pileus opacjue, not translucent, I-4 cm. in diameter, cilia long, of uncertain dura- 



tion, plants mostly cespitose. 1 8. P. Tricholoma. 



Pileus very thin, more or less translucent, 1-2 cm. in diameter, cilia short, slender 



fugacious, plants not cespitose. 19. P. Cowellii. 



17. Pileus squamose, very large, flabelliform, tubes large, alveolar. 20. P. caudicinus. 

 Pileus finely tomentose, drab- colored, with reddish-brown spots, small, circular, 



tubes rounded, minute. 21. P. maculosus. 



Pileus glabrous, uniform in color, variable in form, tubes punctiform. 18. 



