NORTHERN POLYPORES n 



Tubes much smaller, usually regular and entire. 

 Surface zonate. 



Pileus 1-3 mm. thick, not effused. 7. T. balsameus. 



Pileus 5 mm. or more thick, effused-reflexed. 8. T. Ellisianus. 

 Surface azonate. 



Surface conspicuously villose or tomentose. 



Pileus more or less bluish, not effused. 9. T. caesius. 



Pileus not bluish, effused-reflexed. 10. T. semipileatus. 



Surface glabrous or nearly so. 



Surface pelliculose, more or less tinged 



with gray. n. T. chioneus. 



Surface white, without a pellicle. 



Pileus about 2 mm. thick. 12. T. Bartholomaei. 



Pileus much thicker. 



Edges of tubes obtuse, entire. 13. T. anceps. 



Edges of tubes very thin, lacerate. 14. T. lacteus. 



i. TYROMYCES GUTTULATUS (Peck) Murrill 



Pileus cespitose or gregarious, broad, applanate, sessile or 

 attached by an attenuate base, cheesy-soft when fresh, rigid and 

 fragile when dry, 5-7 X 10-15 X 0.5-1.5 cm.; surface white or 

 yellowish-white, becoming sordid with age, especially at the 

 margin, glabrous, somewhat uneven, slightly zonate at times, 

 marked with numerous rounded, depressed, watery spots, either 

 scattered promiscuously or arranged in zones; margin thin, white 

 to discolored, undulate or lobed; context white, cheesy to fragile, 

 3-8 mm. thick; tubes white, 3-6 mm. long, mouths small, 

 angular, glistening, 4-5 to a mm., white to avellaneous or um- 

 brinous, often sordid-spotted in dried specimens, edges thin, 

 fragile, lacerate; spores globose, 5 /*. 



Frequent on dead coniferous stumps and trunks from eastern 

 Canada to Michigan and Ohio. Compare P. alutaceus Fries. 



2. TYROMYCES OBDUCTUS (Berk.) Murrill 



Pileus thin, fleshy, very fragile when dry, expanding from a 

 wedge-shaped base, 6 X 12 X 0.3 cm.; surface very smooth, 

 yellowish-brown, glabrous, with a gelatinous-horny pellicle, 

 having the appearance of parchment; margin thin, concolorous, 

 reniform-lobed ; context very thin, white, fleshy-tough, becoming 

 fragile and very hard when dry, I mm. or less thick; tubes 

 slender, 1.5-2.5 mm. long, white to yellowish within, collapsing, 

 mouths angular, white to yellowish, minute, 6 to a mm., edges 

 very thin, flaccid, lacerate. 



Collected once on dead trunks in boreal North America 

 below latitude 54. 



