PRIMULA CONFERENCE. 



267 



Amongst diseases of Primulas, the one caused' by the attack 

 of the fungus named Urocystis Primulicola, Magnus, on Primula 

 farinosa, is a notable one. It was illustrated and described (for 

 the first time as British) in the Gardeners' Chronicle for August 

 80th, 1884, pp. 268, 269. Phyllosticta primulacola grows on 

 fading leaves of the common Primrose. 



The Primulaceae have their fair share of species of iEcidium 

 and Puccinia, two sets of fungi which are believed by many 

 botanists to be genetically connected. It happens that the 

 species belonging to the Primulaceas have been called 

 Eu-pucciniae, which means that all the spore forms — Uredo, 

 Puccinia, and iEcidium — are supposed to grow on the same host 

 plant. Beginning with Soldanella, we have Meidium soldandLe, 

 a fungus which was published by Mr. Berkeley in the English 

 Flora, fifty years ago. As far as I know, the Puccinia, which 

 should accompany it on the same host plant, has kept in the 

 background, for it has not yet been seen in Britain. 



Puccinia primula, Greville, grows on Primrose leaves from 

 June to September ; Meidium primula, its supposed second, 

 grows on Primrose leaves in May. The Puccinia is sometimes 

 called Uromyces, at other times, Trichobasis ; the last name has 

 recently been most approved. 



We now come to the two species of Peronospora ; these 

 parasites cause great destruction. The larger in size of the two is 

 P. Candida, Fiickel (fig. 28) ; it forms dense white effused patches on 

 the underside of Primrose leaves in summer and autumn. It is an 

 ally of the Clover Peronospora, and belongs to the group EfTusa?. 

 The second species is P. inter stitialis (fig. 27), a very much smaller 

 plant ; this grows on the underside of Primrose leaves in the sum- 

 mer, and is generally confined to the interstices of the veins ; the 

 conidia are often terminal, i.e. one conidium or spore to a fungus 

 stem. In this simple state it resembles Ovularia. Both fungi 

 produce resting-spores. I am not acquainted with any illus- 

 trations of these fungi other than the two herewith appended, 

 which have been engraved from Nature to the same scale, viz., 

 enlarged 400 diameters. The larger (fig. 28) is P. Candida, Fkl., 

 a very handsome, much-branched fungus ; the smaller, P. inter - 

 stitialis, B. and Br. (fig. 27). Leaves affected with either fungus 

 should be gathered and shown "the primrose way to the everlast- 

 ing bonfire," as the "Porter" says in Macbeth. The abundant 



