PLANT DISEASES 



231 



parasites, which, safe within the tissues of their hosts, bid 

 defiance to most attempts to dislodge or kill them. All the 

 fungi spread by means of spores, minute one-celled bodies that 

 function like the seeds of flowering plants. They are often 



FIG. 168. Live oak in Audubon Park, New Orleans, covered with Spanish 



moss (Tillandsia) 

 This is often regarded as a parasite, but it is an independent plant 



given off in inconceivable numbers. The common field mush- 

 room produces two thousand million spores. Others are capa- 

 ble of shedding a million spores a minute and keeping this up 

 for several days. The largest puffballs may produce twenty 

 million million spores. The spores are extremely small and 



