FOREST TREES OF THE PACIFIC SLOPE. 107 



ing autumn their thin, closely-packed, overlapping scales gradually become 

 loosened from their central spike-like axis and fall away with their winged 

 seeds, two of which are borne under each scale; no fertile or perfect seeds are 

 borne under scales at the ends of the cones. The pointed woody axes of the 

 cones remain attached to their branches for several years. The breaking up of 

 mature cones on the trees is not a character of any other group of our cone- 

 bearers, the deciduous Taxodiums of south Atlantic forests excepted. Seeds of 

 firs are easily wafted by the wind several hundred feet from the parent trees, 

 but they are rarely carried more than 50 or 100 feet away. The seeds have 

 peculiar resin cells which may be seen by cutting into the seed coat. The 

 vitality of fir seeds does not endure beyond a single season, and as a rule the 

 percentage of germination is low (50 per cent or under). Seed-leaves, from 

 4 to 10, and flat. 



Commercially the firs are of great importance. Some of them form protec- 

 tion forests on steep slopes at high elevations where few other conifers can 

 live, while others supply excellent saw-timber of large size. They are moder- 

 ately long-lived, and 350 years is probably the limit of their age, but much is 

 yet to be learned concerning the longevity of our firs. 



Seven species inhabit the Pacific forests; two of them extend far northward 

 into Canada, while one of these and another species range through the Rocky 

 Mountains as well. 



Alpine Fir; Balsam Fir. 

 Abies lasiocarpa (Hook.) Nuttall. 



DISTINGUISHING CHARACTERISTICS. 



Alpine fir is one of the smallest of the Pacific firs and perhaps also one of the 

 least known there, owing to the high altitude at which it grows. Among all of 

 its associates the long, narrowly conical crown, terminating in a conspicuous 

 spire-like point, at once distinguishes this fir from all species of its kind in 

 the region. Its spear-like heads can be recognized at a long distance. Height, 

 from GO to 90 feet and diameter from 14 to 24 inches, but in exposed 

 high situations it may be under 3 or 4 feet in height, with very long lower 

 branches on the ground. Rare old trees attain heights of from 100 to 130 or, 

 very occasionally, 160 feet and a diameter of 3 to 4 feet. Larger trees are 

 reported, but they are exceedingly rare. The bark is thin, at most about 1J 

 inches thick, hard, flinty, and but little broken on fairly large trees, except occa- 

 sional shallow, narrow cracks near the base of the trunk. The unbroken smooth 

 parts are ashy gray — often chalky-white. Even in old trunks, always irregu- 

 larly and shallowly seamed, the flat ridges are whitish, but pale-brownish on the 

 broken edges and red-brown on the inside. Trees on several mountain peaks in 

 Arizona, and occasionally elsewhere in the tree's range, have peculiarly thin, 

 soft, corky <* bark, similar in color to the hard bark. The narrow crown usually 

 extends to the ground, even on old trees. The dense branches, which are char- 

 acteristically tough, droop at the base of the crown; when dead, often curved 

 or bent down upon the trunk. Its low branches make it particularly suscepti- 

 ble to crown fires, which invariably kill it in large numbers, as do severe ground 

 fires, which easily injure its thin bark. In very close stands old trees are occa- 

 sionally free from branches for from 20 to 40 feet or more. The foliage is deep 



"Abies arizonUsa Merriam is founded partly on this character and partly on a form of 

 cone-scale which I >r. Merriam found to differ materially from that of the ordinary type of 

 .1. laaiocarpa. The cones and foliage of the cork-barked trees can not be distinguished by 

 the writer from those of hard-barked trees. 



