6o 



A TEXT-BOOK OF BOTANY. 



FIG. 35. A decaying tree trunk showing the cause of the death of the tree by 

 the appearance of the several fungi (probably Lepiota Americana). It is not unusual 

 to find trees showing signs of disease and, finally, even -dying, and it is not until 

 the death of the tree that the mature fungus makes its appearance. For some years 

 the mycelium of the fungus has been working its way into the tissues not only of 

 the bark but of the wood, sapping it of its vitality. The fungus finally produces its 

 fruit with spores, the latter being scattered by either the wind or through the 

 agency of birds, are carried to other trees and find entrance into wounds, where 

 they germinate and repeat their destruction. From a photograph by Troth. 



