THE POLYPORACEAE OF WISCONSIN. 33 



The largest specimen measures about 2.5 cm. in diameter ; the sub- 

 stance of the pileus is scarcely 0.5 mm. thick and is translucent when 

 moist. The color is somewhat brighter than that of F. europaeus. 



The pores are deep and alveolar as those of F. europaeus but not so 

 large, a little darker in color than the pileus. The stipe is attached 

 centrally. It varies in length from 2 to 3 cm., averaging about 3 mm. 

 in diameter. It tapers upward and is covered with brownish furfur- 

 aceous scales. 



When dry the plant is hard and brittle. 



The distinguishing characteristics are the thin, circular, umbilicate 

 pileus, the favoloid pores and the slender central stem. 



From Polyporus arcularius, which it strongly resembles, it may be 

 distinguished by its lighter color and its delicacy. 



Syn. : Polyporus circular iellus Murrill, 19, 31, p. 36. 



6. DAEDALEA Persoon. 



The genus is readily recognized in most cases by its sinuous and 

 labyrinthine pores. When young the pores are firm and roundish but 

 soon break down into teeth or lamellae, usually woody and hard. 



Daedalca unicolor (Bull.) Fries. 



Pileus leathery, tough, flexible, villous-strigose, ashy zonate, the 

 zones concolorous ; pores labyrinthine, flexuous, acute, at length lacer- 

 ate, dentate; lamellae white; sometimes yellowish. 



This is the commonest representative of the genus and is found in 

 all parts of the state. The species is very variable and occurs on 

 different hosts. It is most often found on old and partly decayed logs 

 and stumps of deciduous trees, but chiefly on poplar, willow, and 

 maple. Occasionally specimens are found on living maple and wil- 

 low trees, growing out of the wounds. The wood on which the speci- 

 mens grow becomes white and brittle. But whether the trees are 

 killed by the plant I cannot state. 



The pileus is usually soft leathery, hirsute and concentrically sul- 

 cate, resembling Polystictus hirsutus when seen from above. Some- 

 times the pubescence is wanting, especially on specimens growing on 

 living maple and willow. The margin is usually rounded. The color 

 of freshly growing specimens is normally yellowish-white or aluta- 

 ceous. Specimens growing on maple trunks and willow are grayish- 

 white. Older specimens become grayish or grayish-black. Old spe- 



3 



