382 



JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



Black Poplar Rust. 

 Melampsora populina (Jacq.), PI. XXI. fig. 36. 



This endophytal parasite occurs commonly on the living leaves of 

 Populus nigra, balsamifera, and italica. It has been affirmed that the 

 cluster-cups are to be found on the Clematis, but this has not been 

 confirmed by those whose unbounded faith rests upon artificial cultures. 



The pustules of the uredo are found on the under surface, are roundish, 

 and at first covered by the epidermis, brown. The uredospores are 

 elongated elliptical, or ovate, and rough (28-40x15-20 yu), of an orange- 

 yellow colour, mixed with capitate paraphyses. 



Teleutospores in flat pustules, generally crowded and often confluent, 

 forming reddish-brown and then blackened crusts. The spores are 

 cylindrical, closely packed side by side, and angular by compression, so 

 that they are polygonal in section, a little attenuated downwards (40-50 x 

 10-15 //), pale brown in colour. 



Known also in France, Belgium, Netherlands, Germany, Finland, 

 Bohemia, Austria- Hungary, Switzerland, Italy, Portugal, Asiatic Siberia, 

 and North America. 



Sacc. Syll vii. 2113 ; Plowr. Br. Ured. p. 242 ; Cooke, Hdbk. No. 

 1561 ; Cooke, M.F. 219, figs. 195, 196. 



Poplar-Leaf Blister. 

 Taphrina aurea (Fr.). PI. XXI. fig. 37. 



This blister on Poplar leaves has long been known on Populus nigra, 

 forming roundish blisters, which are convex on the upper surface and 

 concave beneath, where they acquire a golden-primrose appearance. The 

 asci are clavate, attenuated at the base, and truncate at the apex (92-100 x 

 16-25 fj). The sporidia are globose (4 \i broad). 



The same fungus, apparently, produces pocket-like growths on the 

 ovary of Populus tremula and P. alba (H. & S. fig. 74). 



Known also in France, Germany, Sweden, Finland, and Italy. 



Sacc. Syll. viii. 3325 ; Sacc. F. Ital. fig. 1281 ; Hart. & Som. Dis. 

 Trees, p. 135, figs. 73, 74 ; Mass. PI. Dis. p. 91. 



Another blister (Taphrina Joliansonii, Sad.) attacks the carpels of the 

 Aspen, causing them to swell and become of a bright golden-yellow. Not as 

 yet determined to be British, unless it proves to be the above form of 

 Taphrina aurea. 



Mass. PL Dis. p. 92. 



The Lombardy Poplar is attacked by Didymosphceria populina, which 

 produces a disease met with in many parts of France and Germany. 

 Hart. & Som. Dis. Trees, p. 104. 



Willow-Leaf Spot. 

 Septoria salicicola (Fries), PI. XXI. fig. 38. 



This spot is generally found on the leaves of Salix cinerea and S. 

 rhninalis, but it occurs also upon other species. The spots are rounded 



