132 



PLANTS WITHOUT CHLOROPHYLL 



Another fungus which does much harm to the few trees found 

 in large towns and cities is the shelf or bracket fungus. The part 

 of the body visible on the tree looks like a shelf or bracket, hence 



the name. This bracket is in 

 reality the reproductive part of 

 the plant; on its lower surface 

 are formed millions of little 

 bodies called spores. These 

 spores are capable, under favor- 

 able conditions, of reproducing 

 new plants. The true body of 

 the plant, a network of threads, 

 is found under the bark. This 

 fungus begins its life as a spore 

 in some part of the tree which 

 has become diseased or broken. 

 Once established, it spreads 

 rapidly. There is no remedy 

 except to kill the tree and burn 

 it, so as to destroy the spores. 

 Many fine trees, sound except 

 for a slight bruise or other in- 

 jury, are annually infected and eventually killed. In cities thou- 

 sands of trees become infected through careless hitching of horses 

 so that the horse may gnaw the tree, thus exposing a fresh surface 

 on which spores may obtain lodgment and grow (see page 115). 



Suggestions for Field Work. — A field trip to a park or grove near 

 home may show the great destruction of timber by this means. Count the 

 nimiber of perfect trees in a given area. Compare it with the number of 

 trees attacked by the fungus. Does the fungus appear to be transmitted 

 from one tree to another near at hand ? In how many instances can you 

 discover the point where the fungus first attacked the tree? 



Fungi of our Homes. — But not all fungi are wild. Some have 

 become introduced into our homes and these live on food or other 

 materials. These plants are very important because of their relation 

 to life in a town or crowded city.^ 



Shelf fungi. 

 (Photographed by W. C. Barbour.) 



' Experiments on conditions favorable to growth of mold should be introduced here. 



