20 NORTHERN POLYPORES 



separated from the context by a thin, pink layer, mouths very 

 irregular, dissepiments thicker than the pores, obtuse, entire, 

 crumbling away in age, leaving the smooth, white context; 

 spores cylindric, curved, 4-5 AI in length. 



Common on dead or diseased birch trunks from New Jersey 

 northward and westward to Wisconsin. Sections of large 

 sporophores have been used in Sweden for sharpening razors. 



10. PORODISCULUS Murrill 



Hymenophore small, annual, tough, epixylous, erumpent from 

 the lenticels of dead branches; stipe attached to the vertex of 

 the pileus, usually curved at maturity; context white, fibrous; 

 tubes cylindric, short, one-layered, mouths constricted; spores 

 globose, smooth, hyaline. 



i. PORODISCULUS PENDULUS (Schw.) Murrill 



Pileus very small, turbinate-cup-shaped, attached at the 

 vertex, soon decurved and pendant, gregarious, erumpent from 

 the lenticels of dead branches, 1-2 mm. broad, 3-5 mm. long; 

 surface anoderm, azonate, smooth, umbrinous, uniformly covered 

 with a brown powder, often ashy-white with age; margin inflexed, 

 concolorous, sterile; context white, fibrous, very thin; tubes very 

 short, annual, white within, mouths circular, constricted, white, 

 pruinose, becoming concolorous, 6-7 to a mm., edges entire; 

 spores globose, 4^1; stipe 2 mm. or less in length, vertically 

 attached, gradually expanding into the pileus, which it resembles 

 in surface and context. 



Frequent on fallen dead twigs of various deciduous trees and 

 occasionally on red cedar from Connecticut southward and 

 westward to Missouri and Iowa. Very common in some locali- 

 ties on dead chestnut branches. 



ii. HEXAGONA Pollini 



Hymenophore small, annual, epixylous, flabelliform to reni- 

 form, rarely circular, stipitate, the stipe sometimes much reduced ; 

 surface smooth or tessellate; margin thin; context thin, white, 

 fibrous, fleshy to tough, usually fragile when dry; hymenium of 

 radiating rows of large, thin-walled, hexagonal tubes, usually 

 radially elongate; spores smooth, hyaline. 



Tubes large; surface of pileus decorated with imbricate, reddish- 

 brown fibrils, which disappear with age. i. H. alveolaris. 



Tubes much smaller, the mouths rarely over i mm. long and 0.5 



mm. broad; surface of pileus glabrous. 2. H. striatula. 



