38 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



There are no true perithecia, but the little clots, or openings, on the 

 spots indicate the small cavities beneath, in which the conidia are produced. 

 These cavities are surrounded by abundant dark brown hairs (60-100 

 x 8-5 /<) which are once or twice divided by transverse septa. The conidia 

 are irregularly oblong and colourless (11-28 x 5 /-), but flesh-coloured in 

 the mass. 



Spraying with diluted Bordeaux mixture at intervals, as soon as the 

 leaves appear, proved to be the best preventive. Diseased plants should 

 be destroyed. 



Sacc. Syll. x. 6848 ; Massee PI. Dis. p. 290 ; U.S. Joum. Myc. vi. 

 p. 45, plate ; U.S.A. Dept. Aijric. 1890, pi. 1. 



Hollyhock Black Moulds. 

 Cercospora (sp.). 



It is rather remarkable that no instance has been recorded of the 

 appearance of these black moulds on the foliage of Mallows or Holly- 

 hocks in this country. 



One of these [Cercospora altheina) not only has appeared in Italy, 

 but also in the United States, and another, chiefly on the stems {Cerco- 

 spora nebulosa), in Italy. A third species (Cercospora malvarum) has 

 been found on fading Mallow leaves in France. Other species affect 

 plants of Hibiscus, Sida, &c, but none of them have as yet crossed the 

 Channel. These moulds are characterised by the very long and narrow 

 conidia, which are attenuated upwards, and divided by more or less 

 numerous septa. 



Malvaceous Brands. 

 Uromijces (sp.). 



About five species of one-celled brands (Uromyces) and about as 

 many of two-celled brands (Puccinia), in addition to the Hollyhock 

 disease, attack the foliage of malvaceous plants, especially of Sida, 

 Abutilon, and Hibiscus. Of the former all of them are extra-European, 

 and nearly all of the latter, so that little danger can be feared from them 

 in our greenhouses, save by accident. 



St. John's Wokt Rust. 

 Melompsora hypericorum (DC), PI. III., fig. 44. 



This parasite makes its appearance on the underside of the leaves 

 of various species of St. John's \Yort, including those which are found in 

 gardens. 



The pustules are mostly scattered over the leaves, and are rather 

 ■miall, but conspicuous on account of their bright yellow colour. 



Tlx medospores are those which are usually seen, and are somewhat 

 globose 01 ovate, and sometimes angular, orange-yellow, and powdery, 

 with a rough surface (14 -21 x 11-17 /»). The teleutospores are wedge- 

 luijM «], brown (20 /i long). 



The area in which tins pest has been recognised includes the greater 

 part of Europe, Asiatic Siberia, and the Indian Himalayas. 



So little injury is oaused by this parasite in gardens that no experi- 



