378 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



commonly or profusely, on Oak, Elm, Birch, Willow, and other deciduous 

 trees. It is commonly preceded by honey-dew, upon which the mould 

 thrives and flourishes apace. 



The mould consists of brown creeping hypha\ which are branched or 

 fasciculate, sometimes confluent and forming cellulose ganglia, constituting 

 a thin membranaceous stratum, of a blackish colour. The fertile threads 

 are short, ascending, and branched in the upper portion. Conidia terminal, 

 forming short chains, for the most part two-celled, rarely one-celled, or 

 three-celled (from 5-15 // long), brown. 



Doubtless a state or condition of more complex fungi, such as 

 Capnodium. 



Causes injury by closing the pores or stomata of the leaves, but usually 

 so universal over all the foliage as to defy remedy. 



Sacc. Syll. iv. 2618 ; Berk. & Dcsm. Journ. Horl. Soc. iv. 251. 



Lime-Tree Leaf Spot. 

 Septoria tiUa (West.), PL XX. fig. 28. 



Perithecia on both surfaces, of the leaves, seated on tawny spots, 

 which become pallid in the centre. Sporules straight or curved, 3-4 

 septate (35-40 x2-2^ or sometimes longer). 



Known also in Belgium, Italy, and Austria. 



Sacc. Syll. iii. 2562 ; Grevillea, xiv. p. 76, No. 466. 



Alder-Leaf Spot. 

 Septoria alnicola (Cooke), PI. XX. fig. 29. 



This parasite was first found in Britain on living Alder leaves, and 

 afterwards in Italy. The spots are pallid, brown or tawny, roundish 

 (5-7 m.). The receptacles are minute, black, dot-like, scattered over the 

 spots. The sporules oblong, and straight or curved (about 20- 26 x f /<). 



Sacc. Syll. iii. 2735 ; Cooke, Hdbk. No. 1339 ; Seem. Journ. Bot. iv. 

 p. 97, f. 23 ; Grevillea, xiv. 101, No. 488. 



This is supposed to be a different species from Septoria alni and 

 Septoria aln'ujcna, both of which are found on Alder leaves in Italy, but 

 it is doubtful whether at least one of them is not the same. 



Alder-Leaf Black Mould. 

 Passalora bacill i<jcra (Fres.), PL XX. fig. 30. 



This mould occurs on living and languishing leaves of the Alder, 

 occupying the under surface, forming small olive tufts. The threads 

 simple, collected in bundles, flexuous and obtuse, olive-coloured, septate, 

 often twisted and interwoven amongst themselves. Conidia produced at 

 the tips of the threads, somewhat narrowly club-shaped, with one trans- 

 verse division near the centre (30 50 x 5-7 p). 



Known also in France, Germany, Belgium, and Italy. 



Sacc. Syll. iv. 1040; Sacc. FL Ital. t. 788 ; Cooke, Hdbk. No. 1748. 



