204 Parasitic Moulds and Mildews. [Sess. 



E. ajugce Sacc. — On leaves of Bugle, especially in damp 

 woods and coppices. 



B. torticce, Ces. — Frequent on leaves of Nettle, forming 

 dense dirty-white clusters of conidiophores. 



The species of Dematiese, or black - moulds — the second 

 group of Hyphomycetes — are very numerous. The vast 

 majority of these fungi are saprophytic, and many species 

 occur commonly on decaying leaves, rotten herbaceous stems, 

 and other putrid vegetation. A few, however, may be noted 

 as truly parasitic on living plants. 



Fusicladium dendriticum Fckl. — Common on leaves and 

 unripe fruit of Apple, where it forms effused velvety-brown 

 patches. The conidia are fusoid-clavate, and continuous at 

 first, but finally become uniseptate. 



F. pirinum Fckl., on Pear, is by some regarded as a distinct 

 species from the preceding, from which, however, it differs in 

 only a few minor details. 



Polythrincium trifolii Kze. & Schm. — Frequent on leaves 

 of White Dutch Clover, where its threads form convex 

 cushion - like clusters of a dark olive - brown colour. The 

 conidia are obovate, and two - celled. This is often found 

 associated with Phyllachora trifolii, one of the Pyrenomycetes, 

 of which it is believed to be the conidial state. 



Cladosporittm fulvum Cooke. — This is the well - known 

 fungus of the " Tomato - mould." It was first described in 

 1883, from specimens received from South Carolina, U.S., 

 and its earliest appearance in England was in 1887. It has 

 since spread rapidly over the country, so as to become a 

 destructive pest. It attacks the leaves of growing tomato- 

 plants, forming numerous pale - brown spots which become 

 darker as the conidia are matured. 



Cercospora mercicrialis Fckl, — Common on leaves of Dog 

 Mercury, where it produces conspicuous withered spots of a 

 pale-yellow or whitish colour. The conidiophores are grouped 

 in minute blackish clusters on the pale spots, and are often 

 hardly visible without the aid of a lens. The conidia are 

 narrow, vermicular, pale brown, and divided by septa into 

 several cells. 



Fumago vagans Pers. — Frequent on leaves of various trees 

 and evergreen shrubs, where it forms irregular patches of 



