376 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



Birch-Leaf Spot. 

 Phyllosticta betulina (Sacc), PL XX. fig. 25. 



Possibly this leaf-spot bears the receptacles of the earliest stage, or 

 spermogonia, of a species of leaf sphaeria (Sphcerella maculiformis) which 

 is not uncommon on the dead leaves of various kinds of forest trees. 

 There are no definite spots, but the receptacles are densely clustered 

 together in large groups, which have the appearance of spots. These are 

 globose, and immersed in the substance of the leaves, and contain minute 

 curved sporules (4-6 x 1-1^ /j), which are ejected when mature. 



Recorded also in France and Italy. 



Sacc. Syll. in. 170 ; Grevillea, xiv. 72, No. 398. 



Another leaf-spot on Birch is attributed to Asteroma betulce, which 

 occurs in Britain, but is not reputed to cause any serious injury 

 Sacc. Syll. iii. 1241 ; Grevillea, xiv. p. 75, No. 446. 



Birch-Leaf Bust. 

 Melampsora betulina (Pers.), PL XX. fig. 26. 



This rust is common on Birch leaves from May to November. Hitherto 

 all efforts to discover the cluster-cups of this species, presuming them to 

 exist, have been unavailing. 



The pustules of the uredo are small, pale orange, roundish, and rather 

 powdery. The uredospores are ovate or oblong (25-40 x 10-20 /x), finely 

 rough, and orange-yellow. 



The pustules which contain the teleutospores are at first yellow, then 

 they become brown, and ultimately black. The spores are cylindrical, 

 partaking of the typical form of the genus, closely packed side by side, 

 and slightly wedge-shaped (50 x 16 pale yellow-brown. 



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

 Lapland, Austria, Hungary, Switzerland, Italy, and Asiatic Siberia. 



Sacc. Syll. vii. 2118 ; Ploivr. Br. Ured. p. 243 ; Cooke, Hdbk. No. 1559 ; 

 Cooke, M. F. 219, figs. 189, 190 ; Hart. & Som. Dis. Trees, p. 171. 



Birch Polypore. 



Polyporus betulinus (Fr.). 



Although this polypore has long been known as a saprophyte on dead 

 Birch trees, it has only recently been demonstrated that it will attack and 

 destroy living trees, producing at first a brown discoloration and after- 

 wards causing cracks in the decaying wood, which is replete with the 

 white mycelium. 



The complete fungus, when seen attached to the trunk, is hoof-shaped, 

 with the upper surface smooth and at first soft, white, or greyish, and 

 often brownish as it advances in age, when the brown cuticle often cracks 

 and peels off. The under surface is flat, or a little concave, pierced all 

 over with minute pores ; the margin thick and curved inwards. When 

 young, the substance is soft enough to be cut like cheese, and is per- 



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