512 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



mycologists as a distinct species, P. chrysanthemi Roze, probably restricted 

 to the Chrysanthemum. 



Recently, however, we have received from different localities specimens 

 of Cineraria leaves attacked by one of the rust fungi, for which growers 

 would do well to be on the watch, particularly as the fungus in question 

 is one that is extremely common on one of our most abundant weeds, 

 the groundsel (Senecio vulgaris), and is distributed in all the districts of 

 our island and the continent of Europe, wherever both the groundsel 

 and the Scots pine are found. The fungus is known as Coleosporium 

 senecionis, and in addition to the groundsel other species of Senecio 

 (S. Jacobaea, S. viscosus, S. sylvaticus, S.jxdustris, S. vemalis, S.pulchrum, 

 and perhaps S. doronicum) are subject to its attacks. It is not, therefore, 

 surprising that a plant so nearly related to these Senecios as Cineraria 

 should at last fall a victim. 



Fig. 92. 



a, Cineraria with fungus {Coleosporium senecionis) ; b, uredospores ; c, teleutospores. 

 (b and c much magnified.) 



The attack is characterized in all cases by the appearance on the 

 under surface of the leaves of orange-yellow, waxy-looking patches 

 (fig. 92, a) covering areas varying from about \ inch in diameter to almost 

 the whole of the lower surface of the leaf. The leaf, when the attack is 

 a slight one, shows scarcely any injury on the upper surface ; but as the 

 disease spreads it may become blackish in colour. The yellow patches 

 appear in September, and consist of masses of one-celled yellow spores 

 (fig. 92, b), known as uredospores, capable of immediate germination and 

 of infecting fresh leaves of the Cineraria and of the species of Senecio 

 mentioned above. Later the patches become red, and then consist of 

 large numbers of the winter form of spore, the three- or four-celled 

 teleutospores (fig. 92, c). On the germination of the teleutospore in the 

 spring another form of spore is produced at the end of the short hyphae 

 which proceed from the teleutospore cells. This third form of spore is 

 called a sporidium, and is incapable of reproducing the disease upon the 



