34 TREES OF NORTH AMERICA 



coated with hoary tomentum usually persistent until after their second winter, ultimately 

 becoming nearly black, and prominent winter-buds with conspicuous long white matted 

 hairs fringing the margins of their scales and often almost entirely covering the bud. 

 Bark of young trees and of the branches thin, rather lustrous, smooth, and pale gray 

 tinged with yellow 7 , becoming loose and scaly on larger stems and on the large branches of 



old trees, and on fully grown trunks i'-f thick and slightly divided by shallow fissures into 

 irregularly shaped plates covered by thin dark-red brown loosely attached scales. Wood 

 heavy, hard, coarse-grained, light reddish brown. 



Distribution. Near the timber-line on mountain slopes at elevations of 4000-8000, 

 from southern Alberta on the eastern slope of the Rocky Mountains and from the interior 

 of southern British Columbia, southward along the eastern slopes of the Cascade Moun- 

 tains of northern Washington to Mt. Stewart at the head of the north fork of the Yakima 

 River, and along the continental divide to the middle fork of Sun River, Montana, form- 

 ing here a forest of considerable size at elevations of 7000-8000, and on the Bitter Root 

 Mountains to the headwaters of the south fork of the Clearwater River, Idaho. 



3. PICEA Dietr. Spruce. 



Pyramidal trees, with tall tapering trunks often stoutly buttressed at the base, thin 

 scaly bark, soft pale wood containing numerous resin-canals, slender whorled twice or 

 thrice ramified branches, their ultimate divisions stout, glabrous or pubescent, and leaf- 

 buds usually in 3's, the 2 lateral in the axils of upper leaves. Leaves linear, spirally dis- 

 posed, extending out from the branch on all sides or occasionally appearing 2-ranked by 

 the twisting of those on its lower side, mostly pointing to the end of the branch, entire, 

 articulate on prominent persistent rhomboid ultimately woody bases, keeled above and 

 below, 4-sided and stomatiferous on the 4 sides, or flattened and stomatiferous on the upper 

 and occasionally on the lower side, persistent from seven to ten years, deciduous in drying. 

 Flowers terminal or in the axils of upper leaves, the male usually long-stalked, composed 

 of numerous spirally arranged anthers with connectives produced into broad nearly circu- 

 lar toothed crests, the female oblong, oval or cylindric, with rounded or pointed scales, 

 each in the axis of an accrescent bract shorter than the scale at maturity. Fruit an ovoid 

 or oblong, cylindric pendant cone, crowded on the upper branches or in some species 

 scattered over the upper half of the tree. Seeds ovoid or oblong, usually acute at base, 

 much shorter than their wings; outer seed-coat crustaceous, light or dark brown, the inner 

 membranaceous, pale chestnut-brown; cotyledons 4-15. 



