108 



Mycologia 



Poronidulus conchifer (Schw.) Murrill 

 Polystictus conchifer (Schw.) Sacc. 

 Shell-bearing Poronidulus 



Plate 6. Figure 2. X 1 



Pileus thin, coriaceous, dimidiate to flabelliform, usually nar- 

 rowly attached, conchate, springing from a sterile, cup-like struc- 

 ture, which usually appears on the mature sporophore near the 

 base, 1.5-2 X 2-4 X 0.1-0.2 cm. ; surface white to isabelline, with 

 pale-latericeous zones, finely tomentose to glabrous, the sterile 

 portion avellaneous, with narrow, black, concentric lines ; margin 

 thin, concolorous, undulate ; context very thin, membranous, white, 

 less than 1 mm. in thickness ; tubes short, about 1 mm. long, thin- 

 walled, white, mouths angular, irregular, 3 to a mm., edges thin, 

 uneven, dentate; spores ellipsoid, smooth, hyaline. 



Very common on dead elm branches in the eastern United 

 States and Canada. It occurs rarely on a few other deciduous 

 trees. None of our other polypores produce the peculiar sterile 

 cups, which appear on the fertile hymenophores as " shells." 



Polyporus Polyporus (Retz.) Murrill 

 Polyporus brumalis (Pers.) Fries 

 Winter Polyporus 



Plate 6. Figure 3. X 1 



Pileus circular, convex to plane, slightly umbilicate at times, 

 2-8 X 0.2-0.4 cm. ; surface fuliginous, more rarely yellowish- 

 brown, hispid-squamulose to minutely hispid ; margin at first in- 

 flexed, thin, fimbriate, often becoming wavy or lobed' context 

 milk-white, membranous, 1-3 mm. thick ; tubes adnate, white to 

 pallid, 1-2 mm. long, cylindric, mouths circular, regular, 2-3 to 

 a mm., edges at first thick, becoming thin and often dentate with 

 age ; spores cylindric, subcurved, hyaline, 7-8 X 2^3 ^ ; stipe 

 central, solid, woody, equal, squamulose, avellaneous, not black at 

 the base, 2-3 cm. long, 3-7 mm. thick. 



Common in North America and Europe, especially northward, 

 on decayed fallen branches, stumps, and roots of various deciduous 

 trees. It may be found at almost any time during the winter 

 months, as well as in autumn. Species of this form, with central 

 stipe, constitute the genus Polyporus as at present limited, which 

 includes nearly forty North American species. 



