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

FOREST TREES OF THE PACIFIC SLOPE. 77
mouth; Kantishna River, one patch between head and Toklat River; Tolovana River, two
patches onl north tributaries ; Baker Creek, one patch on head tributary ; Kuskokwim
River, noted on its tributary Tonzona River. Also reported from upper Copper River.
The detailed range of tamarack east of the Pacific region will be dealt with
in a future bulletin.
OCCURRENCE.
Most abundant in sphagnum swamps and muskegs, but of largest size on better drained
margins of swamps and lakes, moist, porous benches, and bottomlands; thrives also on
well-drained hillsides. In parts of British Columbia, characteristic of damp, cool, north
slopes. Grows on shallow, moist soils of nearly every consistency, from stiff clay to
coarse sand. Thrives on moderately retentive loams, especially those with rich leaf
mold. Occurrence in saturated soil seems to indicate not a special requirement,
hbt ability to exist where other species more tolerant of shade can not grow. It does
not do well where its roots are constantly submerged. Near confluence of Tanana and
Yukon rivers in Alaska it occurs in open scattering stands, while in its eastern range it
forms rather dense, pure growths. At best, the crown cover is never very dense. Commonly
associated in mixed stands with black spruce, black cottonwood, alder, and willows.
Other far northwestern associates have not been determined.
CLIMATIC CONDITIONS.-With the widest range of all American conifers, it experiences
great diversity of climate. In the Atlantic region, it grows in a humid climate with
frequent fogs and an annual precipitation of from 30 to 50 inches; and seasonal temperature
is moderate-30' or over 100° F. being rare. But in north British Columbia and
Alaska it is subjected to great seasonal ranges of temperature and to pronounced atmospheric
dryness; temperature falls to -60' or -80' F. during winter and often goes
above 100° F. In summer. The precipitation may be as low as 12 inches, and the growing
season for tender vegetables may not exceed three weeks.
TOLERANcE.-Requires a great deal of light throughout life, and at no time endures
heavy shade.
REPRoDtJcTIoN.-Frequent and abundant seeder. Some seed is borne annually, but
especially abundant production occurs about every 2 to 4 years. Seed have only moderate
rate of germination and moderately persistent vitality. Young trees often produce
cones when from 10 to 20 years old. Conditions favorable to germination and growth
are fresh organic or mineral soil, with a protecting cover of spare grass or herbs.
Seedlings require this slight protection at first, and then grow fairly rapidly in height,
so that they persist in mixture with more tolerant but slower growing species of the
same age.
PICEA. SPRUCES.
The spruces are evergreen trees with sharp-pointed, pyramidal crowns and
conspicullosly straight, tapering trunks. The branches grow in regularly distant
circles. Their stiff, often very keenly pointed, single leaves have a characteristic
spiral arrangement on the branches, to which those of each season's
growth adhere for from about seven to ten years. All but two of the North
American species have more or less distinctly 4-angled leaves. Of the exceptions,
one species has flat and only indistinctly 4-angled leaves, while the other
species Ias flat-triangular leaves. MSale and female flowers are borne on tie same
tree and on twigs of the previous year's growth. Mlale flowers, pollen-bearing
only, are drooping, yellow, bright purple, or rose-red, long or short cylindrical
bodies (about three-fourths inch to 1 inch by one-fourth to one-half inch),
while the female flowers, which produce cones and seed, are erect, yellowishgreen
or bright red bodies of similar form, from three-fourths inch to about
1f inches in length by one-fourth to nearly three-fourths inch in diameter.
The cones, which are matured in one season, are cylindrical or egg-shaped,
always drooping or bent downward (figs. 29-33). Most spruces bear their cones
at the extreme top of the crown, while some bear cones only on branches of
the upper half of the crown. After shedding their seed, in early or late fall,
the cones either drop from the trees by spring or remain on the branches for
a number of years. The scales of spruce cones are thin and without prickles,
in contrast to the thick, strong cone scales of pines, which often have sharp,
strong prickles. The scales are firmly attached, as in the pines, to a woody
151 S8-08 6