436 THE FUNGI WHICH CAUSE PLANT DISEASE 



It occurs on oak and maple '° as a wound parasite, destroying 

 bark and cambium. This and related species are usually 

 saprophytic. 



F. pinicola (Fr.) Cke.«^ 



Pileus corky to woody, ungulate, 8-15 x 12-40 x 6-10 cm.; 

 surface glabrous, sulcate, reddish-b^o^vn to gray or black, often 

 resinous; margin at first acute to tumid, palUd, becoming yellowish 

 or reddish-chestnut: context woody, pallid, 0.5-1 cm. thick; tubes 

 distinctly stratified, 3-5 mm. long each season, white to isabelline, 



Fig. 310. — Fomes applanatus. After Clements. 



mouths circular, 3-5 to a mm., edges obtuse, white to cream-colored ; 

 spores ovoid, smooth, hyaline, 6 /x; hyphse 8 m; cystidia none. 



It occurs on conifers; pine, hemlock, spruce, balsam, larch, etc., 

 more rarely on beech, birch and maple, as a wound parasite of 

 the heart wood. The sporophores are often absent until after 

 death of the host. The tracheids bear many holes. The wood 

 carbonizes, the cellulose is destroyed and sheets of mycelium form, 

 particularly within the space occupied by the medullary rays and 



* 96 329 • V */ 



in tangential crevices. ' Fig. 309. 



F. applanatus (Pers.) Wallr. 



Pileus hard, woody, dimidiate, applanate, 6-15 x 8-30 x 1-4 cm. ; 

 surface milk-white to gray or umbrinous, glabrous, concentrically 

 sulcate, encrusted, fasciate with obscure lines, condia-bearing, 



