De I. VNER VEW D Forest Trees of the Pacific Slope

FOREST TREES OF THE PACIFIC SLOPE.
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 conebearers,
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, froni
4 to 10, and flat.
Commercially the firs are of great importance. Some of them form protection
forests on steep slopes at high elevations where few other conifers can
live, while others supply excellent saw-timber of large size. They are moderately
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.
DISTINGtJISIINOG CIIARACTERISTICS.
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 60 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 11
inches thick, hard, flinty, and but little broken on fairly large trees, except occasional
shallow, narrow cracks near the base of the trunk. The unbroken smootn
parts are ashy gray-often chalky-white. Even in old trunks, alvays irregularly
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 a bark, similar in color to the hard bark. The narrow crown usually
extends to the ground, even on old trees. The dense branches, wvhich are characteristically
tough, droop at the base of the crown ; when dead. often curved
or bent down upon the trunk. Its low branches make it particularly susceptible
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 occasionally
free from branches for from 20 to 40 feet or more. The foilage is deep
Abies arizonica Merriam is founded partly on this character and partly on a form of
cone-scale which Dr. Merriam found to differ materially from that of the ordinary type of
A. lasiocarpa. The cones and foliage of the cork-barked trees can not be distinguished by
the writer from those of hard-barked trees.
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