Il8 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



i6. Japanese Larch {Larix leptolepis) and 

 the New Disease. 



By George Leven. 



To the casual observer the individual trees of a species, in 

 a well-grown plantation, are more or less alike, but to the 

 trained observer and the forester, it has long been a common- 

 place that no two trees are exactly the same. That this 

 condition obtains in the case of the Japanese larch, when grown 

 under silvicultural conditions, is undoubted. Observations, 

 extending over a period of ten years, have indeed led the 

 writer to the conclusion that very great dissimilarity exists in 

 this species as generally grown in this country, and that while 

 the present condition of our knowledge, as regards its variations, 

 would not justify our speaking of "varieties," it might be 

 admissible to speak of " types," not so much from a forester's 

 or timber merchant's point of view, as in regard to some 

 of their outstanding characteristics. Under present conditions 

 in this country, where our observations are more or less confined 

 to immature specimens, it would be imprudent to dogmatise, 

 but, broadly speaking, it is evident that there are at least three 

 well-defined types, which may, for simplicity of definition, 

 be termed the "fissure-barked," the "flake-barked," and the 

 " smooth-barked." It is at once evident, on examining a series 

 of trees, that this forms a very tentative classification, as 

 individual stems may be met with that would be difficult to 

 place in their right class. This may be due to various influences 

 that need not be considered here. 



In practically every area that the writer has examined the 

 fissure-barked type predominates It has a certain resemblance 

 to the typical European larch, so far as the bark is concerned, 

 with a more or less well-defined longitudinal ridge and 

 fissure alternating. The thickness of the "cork" portion of 

 the bark is naturally greater than is the case with either of 

 the other two types, and the cork is persistent, i.e. does 

 not scale off". The fissured bark is fairly evident at an early 

 age, and of course is more pronounced towards the bottom of 

 the stem and on the opener-grown specimens. This, probably, 

 is the quickest growing of the three types, but it is inclined to 

 gross branch-formation and to a rambling growth in the case 



