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

88 FOREST TREES OF THE PACIFIC SLOPE.
than 1300 F., not uncommonly failing to -- 60° F. in winter and sometimes above 1000 F.
during summer. Growing season for tender vegetation is from about four months, in
western British Columbia and eastern Alaska, to three weeks on Bering Sea coast.
Owing to high latitude, sunlight is less intense during growing season, but of longer daily
duration than farther south. In winter, insolation is very weak.
TOLERANcE.-Very tolerant of shade, and recovers from suppression up to advanced age.
In dense stands it produces heavy crown cover, and frequently shades out tamarack.
Most tolerant on wet soils, which it covers with dense stands of slow-growing trees, and
least tolerant in dry, well-drained situations, where it grows in more open stands. Retains
side branches for a long time, producing clear trunks only in very dense stands.
REPRODUCTION.-Not a prolific seeder, although some seed is usually borne locally each
year; abundant seed production only at rather long, Irregular intervals. Seed of moderately
high germination and with persistent vitality. Germination best on constantly
moist mineral and humus soils; seed germinates well also in forest on decayed fallen
trees, moss, and moist decomposed spruce leaf litter. Leaf litter in broadleaf forests
not as a rule favorable to germination. Seedlings demand moderate shade for first one
or two seasons.
White Spruce.
Picea canadensis (Mill.), B., S., & P.
DISTINGUISHING CHARACTERISTICS.
White spruce is considered here because of its range in the interior (at least)
of Alaska. It is mainly a tree of the northeastern United States and of Canada,
with a very wide distribution in the latter region. In Alaska white spruce
varies, according to situation, from a stunted form from 8 to 20 feet high to a
well-grown tree from 50 to 75 feet in height and from 12 to 20 inches in diameter;
much larger trees occur on very favorable sites. Elsewhere it reaches
from 80 to 100 feet or more in height, and from 24 to 36 inches in diameter.
Trees 3 or 4 feet in diameter and over 100 feet high are rather rare. The trunk
is straight, smooth, and clear of branches for one-third to two-thirds of its
length, with a somewhat open, irregular, and widely pyramidal crown, the top
of whieh, especially in old trees, may be rounded or flattened; very often, however,
the crowns are sharply pointed. The branches are long and thick, and commonly
curve down and then upward. A striking character of branches is their
Iunuerous small, drooping side branchlets. The dense foliage is also characteristic
in its light blue-green color, which in some individuals has a distinct
whitish tinge. This character has doubtless given the tree its widely recognized
common name, " white spruce." Bark of trunks is thin (one-half inch thick)
and is early broken into small, thin, pale, ashy-brown scales; the color varies
greatly with the density of the stand. The 4-angled leaves (fig. 33) stand out
all around the twigs, except at and near their ends, where they are massed on
the upper side; those on the lower side are curved toward the upper ones.
Twigs of a season's growth are dark yellow-brown; as a rule they are smooth,
but on the far northwestern forms they are apt to be finely downy. A notable
character of the young shoots and leaves is the fetid, polecat-like odor they
emit when bruised; foliage a year old or older gives off a much less distinct
odor. This peculiarity has given the tree its name of " cat spruce." The cones
(fig. 33) ripe by the end of the summer, shed their small light clay-yellow-brown
seeds (33, a) in September. The pendulous cones are lightly attached and usually
fall during autumn or by spring. After shedding their seeds the cones are a
light clay-brown, whereas just at maturity they may be light grass-green tinged
with red or bright rose-red. They vary from about 1 to nearly 2j inches in
length, but they are usually about 11 inches long. When open and dry the conescales
are so thin and flexible that they can be squeezed together without breaking
them. Seed-leaves, about 6, very slender, and one-half to nearly threefourths
of an inch long. Wood, pale yellowish white, soft, very straight and