INJURIES INDUCED BY PLANTS 171 



and in autumn. These small cushion-like bodies, which are at 

 first pale brown and later very dark brown in colour, pass the 

 winter in the tissues of the decaying leaves that are lying on the 

 ground, and produce promycelia and sporidia in spring. These 

 sporidia are carried by the wind to the leaves of the young willow- 

 shoots, and induce the disease afresh. They produce Cceoma 

 Ribesii on the leaves of Ribes alpinum, R. Grossularia, R. nibrum, 

 and R. nigrum. This aecidium form appears, however, to pos- 

 sess merely a facultative character, for we annually meet with 

 numerous instances of the disease, especially in autumn, even in 

 places where no examples of Ribes are to be met with for long 

 distances. 



Hitherto I have met with serious infestations of the fungus 

 only on Salix pruinosa (syn. caspica, acutifolid), numerous osier- 

 beds being entirely destroyed by repeated premature defoliation. 

 The best preventive measures consist in raking together and 

 burying or burning the fallen fungus- infested leaves from 

 autumn till spring, and in careful attention to the osier-beds 

 during summer. As soon as the rust appears sporadically it is 

 advisable to cut off and bury the infested shoots. In place of 

 the glabrous-leaved Salix pruinosa, which suffers most from the 

 fungus, the cultivation of the hybrid 6". pruinosa x daphnoides 

 is to be recommended, the latter being pubescent, and thus better 

 protected against infection. 



MELAMPSORA CAPREARUM 



This willow-rust is very common on Salix Caprea, S. cinerea, 

 S. aurita, S. longifolia, S. repens, and 5. reticulata. It produces 

 the aecidia of Cceoma Evonymi on Evonymus. 



Then we also meet with Melampsora epitea on S. alba, 

 S. incana, S. purpurea^ S. nigt icans, and S. retusa ; and M. 

 mixta on 6". triandra, S. hastata, and 5". silesiaca. 



M. betulina occurs on various species of Betula. 



M. Carpini Carpinus Betulus. 



M. Sorbi ., Sorbus Aucuparia and 5. torminalis. 



M. A rice ,, Sorbus Aria. 



M. Padi Prunus Padus. 



M. Vaccinii ,, Species of Vaccinium* 



* [Several of these are recorded for this country, and are much in need of 

 thorough investigation. ED.] 



