194 STUDIES OF AMERICAN FUNGI. 



of the fungus. The fruiting surface is white, and the tubes are very 

 minute. They scarcely can be seen with the'lunaided eye. Bruises 

 of the tubes turn brown, and certain "artists" often collect these 

 plants and sketch with a pointed instrument on the tube surface. 

 For other peculiarities of this plant seepage 15. The age of the 

 plant can usually be told by counting the number of the broader 

 zones on the upper surface, or by making a section through the plant 

 and counting the number of tube strata on the lower surface of the 

 cap at its base. 



Polyporus leucophxus Mont., is said to differ from this species in 

 being more strongly zonate, and in the crust being whitish instead of 

 reddish brown. 



Polyporus fomentarius (L.) Fr. [Fonh'S fomciitariiis (L.) Fr.,] is 

 hoof-shaped, smoky in color, or gray, and of various shades of dull 

 brown. It is strongly zoned and sulcate, marking off each year's 

 growth. The margin is thick and blunt, and the tube surface con- 

 cave, the tubes having quite large mouths so that they can be readily 

 seen, the color when mature being reddish brown. Sections of the 

 plant show that the tubes are very long, the different years' growth 

 not being marked off so distinctly as in P. applanatiis and Icucophivus. 

 The plant grows on birch, beech, maple, etc. The inner portion was 

 once used as tinder. 



Polyporus pinicola (Swartz.) Fr. [Fomes piukola (Swartz.) Fr.] occurs 

 on dead pine, spruce, balsam, hemlock spruce, and other conifers. The 

 cap is about the width of the F. applanatiis, but it is stouter, and does 

 not have the same hard crust. The young growth at the margin, 

 which is very thick, is whitish yellow, while the old zones are red- 

 dish. The tubes are yellowish, and sections show that they are in 

 strata corresponding to the years' growth. Polyporus igniarius (L.) 

 Fr. \_Fomes igniarius (L.) Fr.] is a black species, more or less trian- 

 gular, or sometimes hoof-shaped. The yearly zones are smaller, 

 become much cracked, and the tubes are dark brown. One of these 

 plants which 1 found on a birch tree in the Adirondacks was over 8q 

 years old. 



