WHITE MILDEWS OR BLIGHTS. 1G7 



torted ; their petioles and tlie peduncles and calyces 

 of tlie flowers swollen_, distorted^ and grey with 

 mould j 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 {8plicerotheca 

 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-sweet, 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. 



