WHITE MILDEWS OR BLIGHTS. 167 



torted ; their petioles and the peduncles and calyces 

 of the flowers swollen^ distorted^ and grey with 

 mould ; and the whole plant looking so diseased 

 and leprous that it needs no mycologist to tell that 

 the rose is mildewed. The conceptacle in this spe- 

 cies is minute^ and contains but one sporangium^ 

 which is one of the characters of the genus in which 

 it is now included^ and a more justifiable distinction 

 than the ramifications of the appendages. The my- 

 celium is rather profuse_, and the threads or appen- 

 dages which spring from the conceptacle are simple 

 and floccose (fig. 216). The sporangium contains 

 eight ovate spores. This species {SjJicerotheca 

 pannosa, Lev.)^ in its oidioid or conidiiferous form^ 

 was for some time known under the name of Oidium 

 leucoconium . 



An allied species constitutes the hop-mildew^ a 

 visitation with which some of our Kentish friends 

 are too familiar. This is not a prejudiced species 

 in the choice of its habitation^, since it is found on 

 many other plants^ where it flourishes with equal 

 vigour. The meadow-sweety burnet^ scabious^ 

 teasle^ dandelion^ and other composite plants^ plan- 

 tain^ and plants of the cucumber family^ all suffer 

 more or less from its roving disposition. The my- 

 celium of whitish threads is even more conspicuous 

 than in the last species^ but the conceptacle s are 

 often not to be found at all. These are also very 

 minute and most common on the under surface of 

 the leaves. The appendages^ or fulcra^ are simple^ 



