Parasitic Root Diseases of the Juncaceae. 
BY 
E. J. SCHWARTZ, M.A., B.Sc., F.L.S. 
With Plate XL. 
A T the suggestion of Professor W. B. Bottomley, to whom I am grateful 
for advice given during the progress of my work, I decided to under¬ 
take an investigation into the nature and structure of the tubercles or 
swellings which are frequently to be met with on the roots of various species 
of Juncus and Cyperus. The present communication (of which a pre¬ 
liminary notice, under the title of ‘ A new Parasitic Disease of the J uncaceae \ 
appeared in the ‘ Annals of Botany January, 1910) is the outcome ofthat 
suggestion. On looking up the literature of the subject I found that the 
structure and cause of the tubercle formations on the roots of Juncus 
bufonms were discussed by C. Weber in a paper entitled 4 Ueber den Pilz 
der Wurzelanschwellungen von Juncus bufonius\ which appeared in the 
£ Botanische Zeitung’ in the year 1884. In this paper, in which he confines 
his description and diagrams to the tubercles occurring on J. bufonius , Weber 
states that they may also be found on roots of Cyperus Jiavescens, the 
plant to which the tubercle-forming fungus owes its name. Juncus articu- 
latus [acutijlorus) is also mentioned as a host-plant by Magnus, who assigns 
the fungus causing the tubercle to the genus Schinzia. This genus in¬ 
cluded various uncertain forms, whose sole resemblance to the fungus found 
in the root-tubercles of the Juncaceae consisted in their being similarly 
connected with the formation of root-tubercles or swellings, such for instance 
as Schinzia A Ini and Schinzia Leguminosarum . Weber in his paper 
arrived at the conclusion that the parasitic fungus found in the tubercles 
was nearly allied to the Ustilagineae, and he renamed it Entorhiza Cypericola. 
With this conclusion I am entirely in agreement. 
I had proceeded but a little way with my investigation when I made 
the interesting discovery that the Juncus roots were at times infected by 
two distinct parasitic fungi, viz. the one (the Entorhiza Cypericola) causing 
the formation of the root-tubercles, and the other confined to the roots them¬ 
selves, many of the cells of which were to be seen filled with spherical balls 
of spores, bearing a striking resemblance to the sorospheres of Sorosphaera 
[Annals of Botany, Vol. XXIV. No. XCV. July, 1910.] 
