FUNGI. 31 



to a tree, but in consequence of the starvation of the 

 cambium there is little or no annual growth. Other 

 fungi will destroy the roots and the living bark and 

 cambium of the butt, and often the tree will die, but 

 in the case of trees with a rich flow of resin, such as 

 pines, the resin will not allow the fungus to develop in 

 the wood of the trunk, which remains sound until it is 

 attacked and destroyed by other nonparasitic fungi. 

 The timber in such trees can be saved, if disposed of in 

 time. Firs, on the other hand, are less effectively pro- 

 tected by resin, and the mycelium, entering the trunk, 

 causes decay of the dead heartwood. Twig-inhabiting 

 fungi often cause distortions. 



FUNGI WHICH ATTACK NONVITAL PARTS OF THE TREE. 



This group includes the economically very important 

 wood-destroying fungi. They can not strictly be called 

 parasites, since they live in the dead heartwood. They 

 rarely endanger the life of the tree. Completely hol- 

 low white firs and Douglas firs often appear thrifty. 

 However, these fungi often bring about indirectly the 

 death of the tree by weakening it mechanically to such 

 an extent that it is blown over or broken off in a heavy 

 storm. 



The destruction of valuable timber by these fungi 

 means very heavy financial losses, not only in mer- 

 chantable timber, but in the ensuing depreciation in 

 value of the affected species. Incense cedar, instead of 

 ranking as an " inferior " species, would be one of the 

 most valuable forest trees of the Sierra Nevada were 

 it not for the fact that often as much as 75 or even 



