52 TEE POLYPORACEAE OF WISCONSIN. 



Poria subacida Pk. (Plate IV, fig. 18.) 



Effused, separable from the matrix, tough, flexible, unequal, deter- 

 minate; margin pubescent, narrow, white; pores minute, subrotund 

 2 6 mm. long, often oblique, white, verging toward tawny, flesh be- 

 coming dirty-yellow; dissepiments thin, minutely dentate; odor 

 strongly subacid. 



This is perhaps our commonest Pona,'and is found everywhere un- 

 der decayed logs. I have specimens from Madison, Sparta, Elkhorn, 

 Horicon, Bangor, Crandon, Hazelhurst, Star Lake, Brule, Ladysmith 

 and Shanagolden, on poplar, maple, tamarack and pine logs. 



The color varies from snow white to cream, dirty-yellow and tawny. 

 It always deepens on drying. The surface is always uneven, the mar- 

 gin very narrow and irregular. One large-pored specimen has a 

 broad, soft tomentose sterile margin from which the white mycelium 

 creeps over the surface of the substratum on the leaves and grass. 



The pores cannot always be called minute they are more often me- 

 dium and sometimes quite large and irregular, varying from 0.3 to 0.9 

 mm. in diameter. The length varies from 2 to 6 mm. The dissepi- 

 ments are thin, slightly dentate but often becoming torn. The subicu- 

 lum is thin and brittle when dry. The odor is quite strong and dis- 

 agreeable when fresh but becomes less strong and sweeter on drying. 

 One specimen found under a much decayed tamarack log near Hazel- 

 hurst had a strong anise-like odor, which is quite persistent. 



Old weathered forms have been found almost entirely covered by 

 new growths. The old portions varied in color from dirty-yellow to 

 teinnamon. The tubes in these were unusually long. 



Most of my specimens were found on much decayed wood usually 

 poplar, or oak. The white felt-like mycelium was found everywhere in 

 the cavities of the wood and looks like that of Polyporus adustus, but 

 is less firm. 



Von Schrenk (Bull. 25, U. S. Dept. Agric.) gives an extended ac- 

 count of the destruction caused by this fungus. It appears that it at- 

 tacks living trees and its mycelum grows through the soil to infect the 

 roots. Von Schrenk says it is very destructive especially to dead wood. 



Poria medulla-panis (Pers.) Fries. 



Effuse, determinate, subundulate, firm, smooth, white; slightly mar- 

 gined with a sterile border almost the entire thickness of the plant 

 made up of the rather long pores which are of medium size and entire. 



