13? FLOWERLESS PLANTS 



There are very large numbers of small 

 fungi, amongst which can be numbered some 

 very destructive pests. Evers'body has noticed 

 the black patches on the leaves of the syca- 

 more, which often bring about an earty falling 

 of the foliage. These are due to an Ascomycete, 

 Rhytisma acerimim. Many of these minute 

 fungi, about which the ordinary person scarcely 

 thinks, cause a huge amount of trouble to the 

 gardener and the farmer. The mildews which 

 hamper the grower of roses, the smuts and rusts 

 which wreck a crop of wheat, are all most 

 obnoxious fungus pests which the world could 

 very well do without. Unfortunately, manj' 

 of these small parasitic fungi possess most effi- 

 cient means of increase. During the summer 

 time ordinar}- spores are produced, and these 

 are readj^ for immediate germination. Thus if 

 they do not get into a suitable position almost 

 at once they \\\1\ very speedil}' perish. But 

 in view of the winter special resting spores are 

 developed ; these will not germinate until after 

 a considerable interval. The real purpose of 

 these wdnter spores is to tide the fungus over the 

 time when the host plants have no foliage or, 

 if they are annuals, are not in existence at all. 



