48 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



restoring itself and insect pests cease to menace, as they do at 

 present, the very existence of tree-life. 



The planting of the Hari-enju or False Acacia (Robinia 

 pseudacacia) and the America Yamanarashi or Lombardy Poplar 

 (Popuhis nigra, var. ita/ica), of which so much has been done, 

 is an experiment the value of which time alone can prove. To 

 this report I attach a letter from Professor Charles S. Sargent, 

 Director of the Arnold Arboretum, Harvard University, in which 

 is given the evidence for and against the False Acacia. The 

 so-called America Yamanarashi is not an American but an 

 Italian tree, which has absolutely no claims to value as a forest 

 tree. In landscape gardening it has its proper place in narrow 

 vistas and against tall buildings. Since it grows rapidly it may 

 be regarded as a cheap source of inferior fuel, but from the 

 viewpoint of permanent afforestation work this tree is without 

 value, and its wholesale and indiscriminate planting is to be 

 strongly condemned. 



The experimental planting of exotic trees is desirable and 

 much to be recommended, but it must not be forgotten that it 

 takes at least half a century before any definite opinion of their 

 value as forest trees can be formed. The tendency of certain 

 exotic trees is to grow quickly during the first few years from 

 planting, but after one or two decades the rate of growth 

 slackens and soon ceases, and the trees become prematurely 

 old, decrepit, and valueless as forest trees. In Japan, where 

 trees have been planted from time immemorial, it is the native 

 trees that have been so successfully employed. Re-afforestation 

 work, in any and every country, if it is intended to have 

 permanent value and results must be done with trees 

 indigenous to the country. Chosen is fairly rich in native 

 species yielding useful timbers, and it is these that should be 

 relied upon for the permanent re-afforesting of the country. 



Copy of Letter. 



Arnold Arboretum, Harvard University, 

 Jamaica Plain, Mass., 



1 1 tli September 1 9 1 7. , 

 Dear Mr Wilson, — I am pleased to get your letters of the 

 9th of August. 



You ask me about Robinia pseudacacia. It produces very 

 hard, strong wood which is extremely durable in contact with 



