14 NORTHERN POLYPORES 



9. TYROMYCES CAESIUS (Schrad.) Murrill 



Pileus dimidiate, imbricate, often narrowly attached, with a 

 prominent umbo, variable in habit and size, soft, spongy when 

 fresh, fragile when dry, 1-2 X 3-6 X 0.5-1.5 cm.; surface sod- 

 den, tomentose or villose-tomentose, azonate, murinous or 

 griseous when fresh, becoming caesious or fading to nearly pure- 

 white on drying, often nearly glabrous with age; context white, 

 soft, friable, 5-8 mm. thick; tubes long and slender, 5-10 mm. 

 long, caesious within, collapsing, friable, mouths angular, 3-4 

 to a mm., edges white or bluish-gray, very thin, dentate to long 

 and sharply lacerate; spores elongate, 5-5.5 X 1.5 M- 



Common throughout on dead wood of both deciduous and 

 coniferous trees. 



10. TYROMYCES SEMIPILEATUS (Peck) Murrill 

 Pileus effused, largely resupinate, suborbicular or laterally 



elongate, very narrowly reflexed, the reflexed portion o-i X 2-5 

 X 0.3-0.5 cm.; surface white or pale-isabelline, subvillose or 

 scabrous, azonate; margin thin, undulate, sometimes inflexed; 

 context white, fleshy-tough to fragile, 2-4 mm. thick; tubes 

 short, slender, white to yellowish within, mouths minute, circular 

 to slightly angular, scarcely conspicuous, 7 to a mm., edges 

 thin, very even, entire, white to pallid, often bluish-discolored 

 in spots or blotches; spores subglobose, 6-8 p. 



Common throughout on fallen dead branches of deciduous 

 trees. 



ii. TYROMYCES CHIONEUS (Fries) P. Karst. 



Pileus imbricate, sessile, dimidiate, convex, 2-4 X 3-6 X I 

 cm.; surface sodden, grayish-cinereous or yellowish-white, 

 azonate, smooth, pubescent to glabrous, margin acute but rather 

 thick, entire, concolorous, fertile; context sodden and watery 

 when fresh, with a mild flavor and acid odor, white, homogeneous 

 and fragile when dry, cutting with a smooth surface, 7-10 mm. 

 thick; tubes shorter than the thickness of the context, 2-4 mm. 

 long, white to yellowish within, fragile, mouths even, glistening, 

 angular, sinuous at times, 4 to a mm., white to ochraceous, 

 edges thin, fimbriate-dentate ; spores cylindric, curved, 4-5 

 X 1-2 /*. 



Common throughout on dead branches and trunks of birch 

 and other deciduous trees. 



12. TYROMYCES BARTHOLOMAEI (Peck) Murrill 

 Pileus thin, rather soft, obovate, attached by a flattened, 

 stem-like base, 3 X 3-5 X 0.2 cm.; surface azonate, white, 



