NORTHERN POLYPORES 53 



37. ELFVINGIA P. Karst. 



Hymenophore large, epixylous, sessile, applanate or ungulate; 

 surface sulcate, horny-encrusted; context brown, punky; tubes 

 brown, cylindric, stratose, thick-walled, mouths whitish or 

 yellowish when young; spores brown; conidia present in most 

 species on or near the surface of the pileus. 



Hymenophore annual, persisting above later growths; pileus 



reniform, margin thin; spores roughly echinulate. I. E. lobata. 



Hymenophore truly perennial; tubes stratified; spores smooth 



or nearly so. 2. E. megaloma* 



i. ELFVINGIA LOBATA (Schw.) Murrill 



Pileus applanate, reniform to dimidiate, 5-8 X 10-15 X 1-2.5 

 cm.; surface concentrically sulcate, subzonate, glabrous, fer- 

 ruginous to fulvous, becoming grayish-brown with age; margin 

 thin, rarely rounded, creamy-white, smooth, entire; context 

 punky with some horny fibers, chestnut-colored, slightly zonate, 

 5-8 mm. thick; tubes annual, 5-8 mm. long each season, avellane- 

 ous within, mouths circular, 4-5 to a mm., edges obtuse, entire, 

 cremeous to umbrinous, becoming brownish when bruised ; spores 

 ovoid, dark-brown, asperulate, 8-10 X 6-7 ju. 



Frequent from New York to Iowa and southward on certain 

 deciduous trees, especially oak, causing decay of the trunk. 

 The sporophores are peculiar in being annual. 



2. ELFVINGIA MEGALOMA (Lev.) Murrill 



Pileus hard, dimidiate, applanate, 6-15 X 8-30 X 1-4 cm.; 

 surface milk-white to gray or umbrinous, glabrous, concentrically 

 sulcate, encrusted, fasciate with obscure lines, conidia-bearing, 

 usually brownish during the growing season from the covering 

 of conidia; margin obtuse, broadly sterile, white or slightly 

 cremeous, entire to undulate; context corky, usually rather 

 hard, zonate, fulvous to bay, 5-10 mm. thick, thinner with age; 

 tubes very evenly stratified, separated by thin layers of context, 

 5-10 mm. long each season, avellaneous to umbrinous within, 

 mouths circular, 5 to a mm., whitish-stuffed when young, edges 

 obtuse, entire, white or slightly yellowish to umbrinous, quickly 

 changing color when bruised; spores ovoid, smooth or very 

 slightly roughened, pale-yellowish-brown, truncate at the base, 

 7-8 X 5-6 M. 



Extremely common throughout on dead or diseased trunks 

 of most deciduous trees, and also on conifers in certain sections, 

 causing decay of the sapwood and exposed heartwood. It is 



