14 Our Field and Forest Trees 



instead of being hard and firm, is found to be a 

 mere mass of powder, or a great bundle of very- 

 short, woody threads. Such spoiled timber is 

 called punk. This destruction has been done by 

 plants growing and feeding in the wood. 



Botanists know a score of plants which destroy 

 timber as it stands in the forest, and another score 

 which destroy logs and woodwork. These mis- 

 chief-makers scarcely look like plants. When we 

 think of a plant, our minds picture root, stem, 

 leaves, flower, and seed. But the devourers of 

 the trees have none of these. They are what 

 botanists call fungi. 



A tree fungus starting in life is just a tangle of 

 threads, scarcely thicker than cobwebs. These 

 threads, branching and branching again, go 

 through the wood until it is all interlaced with a 

 flimsy network of them. And wherever the threads 

 penetrate, the wood is destroyed. 



After many cubic feet of valuable timber has 

 been turned to worthless punk, the destroying 

 fungus prepares to sow itself. From some crack 

 in the bark there is thrust forth a hump or knob, 

 and after a while this develops into a woody shelf 

 or bracket (Fig. 7). This is often mistaken for 

 the whole plant. Really, it is merely the fruit- 

 bearing portion; it corresponds to the pods of the 

 pea vine or the berries on a raspberry bush. The 

 main body of the fungus is inside the tree. Lum- 

 bermen call these outgrowths " conches." Many 



