18 THE VICTORIAN NATURALIST. 



ON THE (ECIDIUM AFFECTING THE SENECIO 

 VULGARIS, OR GROUNDSEL. 



By Thomas Shearman Ralph, M.R.C.S., Eng. ; &c. 



(Read before the field Naturalists' Club of Victoria, wth 

 November 1889.,) 



I have been induced to undertake a more particular study of 

 this fungus in consequence of having learned from my friend Dr. 

 Bancroft, of Brisbane, that a fungus affecting the rough-skinned 

 lemon was to be found in the seed, besides showing itself in the 

 substance of the leaf — a fact with which I was not previously 

 acquainted. 



The CEcidiuw, or Cluster Cup fungus, affects the whole of the 

 stem and leaves of the groundsel ; but with the microscope we 

 are able to trace the fine yellow sporular matter into the covering 

 of the seed, and into the seed itself, as well as in some instances 

 into the hairs of the pappus or down which crowns the seed- 

 vessel. 



In order to trace the fungus element into the seed, it is needful 

 to decolourize its cover by applying some strong carbolic acid to 

 it when on the glass slide, and heating this over a flame till it 

 begins to boil, when it will be found to have become transparent 

 enough to show the yellow fungus material in the tissues of the 

 seed cover. The Cup fungus proper is clearly visible to the naked 

 eye, generally covering the greater part of the plant ; but the 

 mycelium, or root part of the fungus, can be traced in the cells of 

 the stem and leaves by the use of the carbolic acid as above 

 indicated. 



The plant is widely distributed, and the fungus will be found 

 upon it sooner or later, climate seemingly having no influence on 

 its development. 



The interest which attaches to this fungus is, that it is of the 

 same genus as that which attacks the barberry in the Northern 

 Hemisphere, and passing on to the cereals, affects them with 

 the rust. So well is this known that in some States in America 

 the barberry is condemned to be exterminated in cereal districts. 

 As we have no barberry plants growing in the open country here, 

 it becomes a question if the source of rust in cereals in these 

 colonies can be traced to the prevalence of this fungus in the 

 groundsel, for the hair-furnished seeds can travel far and wide 

 with every wind that blows. Of course there may be other 

 sources of infection ; but should it be ascertained that the Cup 

 fungus here plays a similar part to that which flourishes in 

 northern latitudes, it would then be desirable to ascertain the 

 source from whence the groundsel itself becomes affected, for this 

 plant is generally found to be attacked by the fungus when dis- 

 covered growing among kitchen garden plants. In the Carlton 



