54 



BRITISH FUNGI 



Such fungi arc a source of great trouble to tlie gardener who selects 

 damp, stuffy, hacWy lighted j^laces for his seed-beds, whereas 

 when open well- ventilated localities are selected, the fungus is 

 held in check. Many kinds of fungi that attack li\-ing leaves, 

 forming coloured patches or brownish spots, and causing the pre- 

 mature fall of the leaf, are also short-lived. This, however, is not 

 always the case. The large black patches resembling blotches of 



" Smutted " oats, caused liy a fungus called Ush'ln^o a7'e>h,-. 



gas-tar, so common on the living leaves of the sycamore and the 

 maple, called Rhytisma accrinum, attacks the leaves soon after they 

 are fully grown, and causes- them to fall prematurely. During the 

 summer the fungus forms a conidial condition of fruit, and con- 

 tinues to grow on the fallen dead leaves throughout the winter, 

 producing a second and higher form of fruit the following spring, 

 just at the time when the sycamore leaves have expanded. These 

 young leaves become infected by the spores of the fungus formed 



