NORTHERN POLYPORES 47 



8. FOMES FRAXINOPHILUS (Peck) SacC. 



Pileus woody, subtriangular, compressed-ungulate, usually 

 decurrent, 5-10 X 6-12 X 2-4 cm.; surface white, pulverulent 

 or finely tomentose, concentrically sulcate, becoming gray or 

 black and rimose with age; margin tumid, white or yellowish, 

 velvety to the touch ; context corky to woody, zonate, isabelline, 

 0.5-1 cm. thick; tubes evenly but indistinctly stratified, 2-4 mm. 

 long each season, white when young, concolorous with the 

 context in the older layers, mouths white, subcircular, 2 to a 

 mm., edges obtuse; spores broadly ellipsoid, smooth, thin-walled, 

 7-8 X 6-7 n. 



Common throughout on living trunks of ash, rarely on other 

 deciduous trees, causing a serious disease. 



9. FOMES LARICIS (Jacq.) Murrill 



Pileus firm, at length fragile, ungulate to cylindric, 3-8 X 5-10 

 X 4-20 cm.; surface anoderm, powdery, white or slightly yellow- 

 ish, concentrically sulcate, becoming slightly encrusted, tubercu- 

 lose and rimose; margin obtuse, concolorous; context soft, tough, 

 at length friable, chalk- white or slightly yellowish, very bitter, 

 with the odor of fresh meal, 1-3 cm. thick; tubes evenly stratified, 

 concolorous, 5-10 mm. long each season, mouths circular to 

 angular, 3-4 to a mm., edges thin, fragile, white, becoming dis- 

 colored and lacerate, wearing away with age; spores ovoid, 

 4 X 5/z. 



Occasional on larch, pine, and spruce trunks in Michigan and 

 westward. Long used in medicine in Europe, where it is much 

 more common. 



10. FOMES POPULINUS (Schum.) Cooke 



Pileus corky to woody, effused-reflexed, rarely applanate, 

 2-4 X 5-10 X 1-3 cm.; surface anoderm, velvety, white or 

 yellowish, usually overgrown with moss or otherwise disfigured 

 with age; margin acute, slightly deflexed, concolorous, blackish 

 where bruised, becoming thicker with age; context punky to 

 corky, white to ochroleucous, 3-8 mm. thick; tubes very dis- 

 tinctly stratified, 1-2 mm. long each season, concolorous, with a 

 resinous luster, mouths subcircular to angular, minute, 5-6 to a 

 mm., edges thin, uneven, white to cremeous, glistening; spores 

 globose, thin-walled, smooth, 3-4 p.. 



Rather common throughout on living trunks of maple and 

 certain other deciduous trees, causing decay. 



