SPRUCE AND BALSAM FIR TREES. 31 



trees results from the cessation of height growth in the leader and 

 an elongation of the older, shorter, upper side branches. All of 

 the branches, except the topmost, have a distinct downward and 

 upward swing. The bark, peculiarly characteristic in this species, 

 is smooth and ashy-brown, with chalky areas on young trunks and 

 regularly and shallowly furrowed on older trees, the long, flat ridges 

 still retaining splashes of gray- white. (PL XVIII.) The bark of 

 very old trees is still more deeply but narrowly furrowed, the ridges 

 being sharper and less conspicuously flecked with white and the 

 general tone pale red-brown with an ashen tinge. In texture the 

 bark is very hard, close, and horny. It is rarely over If inches thick 

 on old trunks and scarcely an inch thick on trees from 18 to 20 

 inches in diameter. 



The deep yellow-green shiny foliage of grand fir is somewhat thin 

 in appearance because of the characteristic two-ranked arrange- 

 ment of leaves on the lower branches. Leaves on these branches are 

 flat, grooved above, blunt, and nearly always distinctly notched at 

 their ends (PL XVI). They appear to grow only from two oppo- 

 site sides of the branches, but many of the leaves are brought into 

 this position by a twist at their bases. Leaves of the lower-crown 

 branches are from about one-fourth inch to 2£ inches long. Leaves of 

 the uppermost branches also are often notched; but here they are 

 usually crowded together in a more or less upright position on the 

 top sides of the sprays and are from about 1 to 1£ inches long 

 (PL XVII). The scattered leaves of the leader are sharp or keenly 

 pointed and from one-half to seven-eighths of an inch long. All 

 leaves are conspicuously white on their under surfaces. The mature 

 winter buds are covered with resin, and the twigs of the season are 

 pale russet-brown and minutely hairy. 



The cones of this fir mature in early autumn, and are very char- 

 acteristic in their clear, light yellow-green color and slender, cylin- 

 drical form (PL XVII). They are about 2£ to 4£ inches long and 

 about 1 to 1£ inches in diameter. The bracts of the cone scales are 

 relatively broad and usually squarish (truncated) at their upper 

 ends (PL XVII, a), or occasionally somewhat heart-shaped or 

 notched at the top end with a small tooth-like point extending from 

 the center. The pale yellowish-brown seeds (PL XVII, b, c) have 

 shiny, faintly yellowish wings. The seed-leaves, which are very 

 slender and pointed, are usually six in number, and about three- 

 fourths of an inch long (PL XVII, d) . 



The wood of grand fir ranks fourth in weight among Rocky 

 Mountain fir woods, a cubic foot of dry wood weighing about 22 

 pounds. It is soft, but firm enough to be useful as lumber, moder- 

 ately wide-ringed and straight-grained. In color it varies from pale 

 10529°— Bull. 327—16 3 



