Shade Tree and Timber Destroying Fungi. 



241 



first be provided. Tliese infection areas are provided in a variety of 

 ways, in general tlieir origin being tlie same as for otber timber 

 destroying fungi wliicli enter throngli wounds. 



The conditions prevailing in a large portion of the mixed forests 

 of the Adirondack i-egion are such that a very common point for 

 entrance is pi'ovided by the falling of the lower limbs. In the 

 mixed forests the sprnces and pines tower so far al>ove the hard- 

 wood as to cnt otf mncli of the liijht. The hardwoods are thus 

 SO shaded that the area of foliage is considerably lessened, manv 

 of the trees having: few limbs, and then bearino- few leaves com- 

 pared with trees in the open, or even in a hardwood forest where 

 all the trees have an equal chance for light. 



A maple tree about 20 cm. (eight inches) in diameter in the 

 mixed forest at Clearwater had been- affected by the Polyponix 

 igniariiis for a number of years. The fruit body was several years 

 old, of a t r i a n g u 1 a r 

 shelvino' form, and IT) 

 cm. broad. Several 

 entire sections of the 

 truid\, one of them bear- 

 ino" the fruit bodv of 

 the fungus, were col- 

 lected and shipped to 

 Ithaca. 



Cross sections of the 

 tree present a very 

 characteristic and often 

 Ijeautiful marking of the 

 w^ood due to the differ- 

 ent stages of decay and 

 the coloration of the 

 w o o d. The more 

 advanced stages of de- 

 cay lie at the centi-e, 

 the less advanced ones 

 toward the periphery. 

 The sound wood at the periphery is limited from the decayed area 

 .16 



75. — Section of maple tree sfiowing effect of myce- 

 lium of Polyporus igniariiis. 



