roll between the fingers, its young bark, smooth and with resin blis- 

 ters, the shape of the tree, and its wood structure. 



It resembles hemlocks in having flat, petioled leaves, but differs 

 from them in the larger size of its cones and in their protruding 

 bracts. The wood often has a slight resemblance to that of hemlock 

 in its grain, but it is highly resinous, while hemlock wood is without 

 resin. 



Douglas fir can be distinguished with certainty from all other 

 conifers except its close relative, bigcone spruce, by its sharp-pointed, 

 conical buds, which are a bright red-brown when mature. It also 

 differs in the form of its upper crown from most other conifers with 

 which it is associated. Its relatively long top branches are inclined 

 upward, and form an ovate, obtusely pointed crown, very different 

 from the narrow, spire-shaped tops of balsam and spruce, and the 

 open crowns of the pines. The foliage, which is retained on the 

 branches for a distance of from 8 to 11 years' growth from the tip, 

 is somewhat lighter and less compact than that of balsam or spruce. 



The bark varies greatly with age. In youth it is smooth and 

 white, with numerous resin blisters. With advancing age it becomes 

 scaly at first and then gradually breaks up into ridges, separated by 

 deep furrows. At the same time it deepens in color, from light gray 

 to a very dark gray-brown. In cross-section it is composed of a 

 cinnamon-brown body, broken up into scales by intersecting narrow 

 streaks of a lighter brown. The bark of mature trees shows regional 

 variations in character, and in some localities, notably the Uinta 

 National Forest, remains scaly for a much longer time than in others, 

 and never becomes so deeply ridged as usual. 



The root system of Douglas fir accommodates itself readily to local 

 soil conditions. On deep, sandy loams it develops a central di^dsion 

 of two or three strong roots which penetrate deeply into the earth, 

 and at the same time sends out numerous relatively shallow lateral 

 roots. On shallow soils it develops a flat, spreading root system, 

 but penetrates into rock crevices and loose soils with a strong tap- 

 root. In dense stands the root system is shallower and smaller com- 

 pared with the height of the tree than in the open, so that the danger 

 from windfall is great after heavy thinnings. 



The only species for which Douglas fir lumber is apt to be mis- 

 taken are the hard pines and larch. Like these, it produces a strong, 

 hard, pitchy wood, especially characterized by broad bands of dark- 

 colored summer wood in the annual rings: but it. is more variable in 

 its diameter growth than these species, and the yearly rings may be 

 narrow, with very little of the brown summer wood, or broad, with 

 nearly as much summer wood as spring wood. It also differs from 



[Cir. 150] 



