FUNGI 



335 



Some Parasitic Fungi. — Other fungi prefer living plants or 

 animals for their food and are therefore classed as parasites. An 

 example is the chestnut blight, which has killed chestnut trees 

 by the thousands in the eastern 

 part of the United States. It 

 produces millions of tiny spores ; 

 which, blown about by the 

 wind, light on the trees, sprout, 

 and send under the bark thread- 

 like mycelia which absorb the 

 food circulating in the living 

 cells, eventually causing the 

 death of the tree. 



Another fungus which does 

 much harm to trees is the shelf 

 or bracket fungus. The shelf - 

 like body is in reality the re- 

 productive part of the plant ; 

 in its lower surface are formed 

 millions of asexual spores, 

 which, when they fall on a dead 

 or a dying tree trunk, may start 

 a new fungus growth. The true body of the plant, a network 

 of threads, is found under the bark. Once established, it spreads 

 rapidly. There is no remedy except to kill the tree and burn it, 



United Stales Dept. of Agric. 



Tree being killed by chestnut canker. 



Shelf fungus, or bracket fungus, on a small branch. 



so as to destroy the spores. Each year many fine trees, sound 

 except for a slight bruise or other injury, are infected and even- 

 tually killed by this fungus. 



