SYLVICULTURE NOTES ON POPLAR. 275 



gnats ( Cecidomyidce}. A weevil, Cryptorrhynchus lapathi, 

 destroys the bark and shoots, especially of S. viminalis. 



Of fungi, several species of Melampsora produce a rust 

 which causes the leaves to die. Polyporus sulphureus 

 produces red-rot in the wood. > 



11. POPLAR = Populus (Tournef.). 



The following three species must be mentioned : 



(a.) Aspen = Populus tremula, L. 

 (b.) White Poplar = Populus alba, L. 

 (c.) Black Poplar = Populus nigra, L. 



a. Aspen. 

 i. UTILITY. 



The Aspen yields a soft light timber, of small dura- 

 bility in the open ; average specific gravity '49 ; 

 heating power small. 



It is used sometimes under cover for buildings, for 

 packing- and cigar-cases, rough cooperage, inner work of 

 carriages, manufacture of matches, and of paper. The 

 charcoal is used in the manufacture of gunpowder. 

 The bark is used in tanning and dyeing (for the latter 

 purpose also the leaves). 



ii. DISTRIBUTION. 



Europe, North Africa, North Asia. Indigenous in 

 Great Britain and Ireland. Ascends to 1,600 feet in 

 Yorkshire ; to 4,000 feet in the Tyrol. 



T 2 



