100 THE POLYPORACEAE OF WISCONSIN. 



tuse, sometimes acute. The surface may be either smooth, even, or un- 

 even and rough. The base is often decurrent. Resupinate and re- 

 flexed forms are also found. The thicker forms are distinguished with 

 difficulty from young Forties igniarius and F. rimosus. Poly poms 

 giltfm is more yellow and somewhat softer. Moreover, it is never 

 stratified. 



Some of the thick forms were submitted to Professor C. H. Peck, who 

 regarded them as well within the limits of the species. 



The species is very destructive to young oaks and hickory, attacking 

 the living trees and producing a rot in the sap-wood, immediately under 

 the bark. Infection seems to take place in wounds produced by break- 

 ing off branches or in exposed roots. The mycelium spreads upward 

 as well as downward, ultimately killing the tree. This disease needs 

 further investigation. 



Syn. : Hapalopilus gilvus (Schw.) Murr. ; 19, 31, p. 418. 



Polyporus nidulans Fries (Plate XI, fig. 34). 



Pileus fleshy, very soft, subpulvinate, villous then smooth, azonate, 

 reddish-gray, of the same color within. Pores long, medium, unequal, 

 angular, tawny-reddish. 



Common, on broken branches lying on the ground. Specimens have 

 been found at Madison, Bangor, South Milwaukee, Star Lake, Crandon 

 and Ladysmith. The largest specimen is about 12 cm. broad, 6 cm. 

 long and 2 — 3 cm. thick. The pilei are somewhat imbricated and in 

 general appearance resemble those of P. cuiicularis. The color, how- 

 ever, is rather a pale gilvous or even cinnamon, sometimes with reddish 

 tints. The surface becomes rough with age and uneven. The margin 

 is acute and slightly incurved. The substance is very soft and spongy. 

 This is especially noticeable when the pileus is soaked in water for a 

 few minutes. 



The hymenial surface is very convex ; the upper surface is usually 

 plane. The tubes are a little longer than the thickness of the flesh and 

 unequal, resembling those of a Trametes. The mouths are medium and 

 angular. The tubes are grayish brown within; the mouths are a little 

 darker than the pileus. 



This species is a little softer than P. rutilans, its nearest ally, and 

 P. gilvus, some forms of which it resembles ; besides it has larger pores 

 ihan either of these species. 



Syn.: Hapalopilus nidulans (Fr.) Karst. ; 13, 3, p. 18. 

 Hapalopilus rutilans (Pers.) Murr.; 19, 31, p. 416. 



