32 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



It is supposed to reach its highest state of development in the 

 State of Oregon and Western Washington, and in the moist 

 regions around Puget Sound, where specimens of 300 feet in 

 height and 27 feet in circumference have been recorded. On 

 the eastern (or Atlantic) slope of the Rocky Mountains, where 

 the rainfall is light and the drying easterly winds especially 

 severe, the tree, naturally, does not attain to those gigantic 

 dimensions. Under the most favourable conditions in the 

 foothills and valleys, its size limit is stated at 150 feet in 

 height and 9 feet to 12 feet in girth. It reaches its greatest 

 altitude in Colorado, where it clothes the mountain sides to a 

 height of 11,000 feet, but at that extreme elevation it has 

 been dwarfed by exposure to a mere bush of 3 or 4 

 feet in height. It will therefore be seen that in its native 

 habitat the Douglas fir is subjected to extremes of heat and 

 cold, moisture and drought, elevation and scorching winds, such 

 as in Britain it would be impossible to find a parallel to ; and 

 when we further take into consideration the magnitude of the area 

 over which it is found indigenous, the comparison shows all the 

 more strongly the extraordinary accommodative nature of the 

 tree. 



The experience gained of the tree in Britain proves its 

 partiality to the hills and valleys rather than to the open plains 

 or plateaux, and no doubt when planted in the former positions 

 its tendency towards great height-growth will be most fully 

 taken advantage of. It is not too exacting as to depth or 

 quality of soil, provided the subsoil is deep and porous and 

 the drainage efficient, but an undrained soil is fatal. 



The genus, which consists of only one species, is represented 

 by several geographically well-defined forms or varieties,^ but 

 for the purposes of this paper it will be necessary to deal with 

 two of these only, the " green " or " Oregon," and the " glaucous," 

 which, by common consent, we speak of as the Colorado 

 variety. That these two varieties have not been sufficiently 

 differentiated from a commercial point of view is a fact only 

 too well known, and has been the cause of much disappoint- 

 ment. They are, however, easily distinguished, both by the 

 form of the trees and the colour of their foliage, and by the 



' In reference to this point, Prof. Balfour, Hon. Botanist, writes: "Some 

 of these are regarded by modern writers as of specific rank, Mayr, for 

 instance, recognises four species in the genus." — IIoN. Ed. 



