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

FOREST TREES OF THE PACIFIC SLOPE. 35
Never forms dense pure stands. Alost abundant in chaparral on east slopes with singleleaf
pibon, oaks, and juniper, and in thinner stands on west and south slopes in dense
chaparral. Number of trees varies per acre from 5 to about 100. In Lowver California,
in open forests, often with single-leaf piflon pine. Throughout its range, heaviest growth
is at higher altitudes than that of phisoa.
CLIMATIC CONDITIONS.-Best growth requires moister climate, without such extremes
of temperature as are endured by single-leaf pifion. Seasonal temperature of its range
between 15' and 100' F. Rainfall averages between 15 and 25 inches throughout its
distribution.
TOLERANcE.-Little known of light requirements, but its growth in dense chaparral
indicates tolerance of shade during early youth.
REPRODUCTIoN.-Moderate seeder; cones often locally produced about every year.
Wingless seeds, shed near tree, are largely eaten by birds and squirrels and gathered
by Indians for food. Exposed soil with little humus most favorable seed-bed. Germination
moderate.
Single-leaf Pine.
Pines monophylia Torrey and Fremont.
DISTINGUISHING CHARACTERISTICS.
Unique among all American species in having single leaves, as indicated by
its scientific name. Generally known as " nut" or " pi)1on " pine, but it is
highly desirable that the distinctive mark of this tree should be fixed by adopting
" single-leaf pine " its its common name. Mature trees have short trunks,
rarely straight, and wide, rather flat crowns of short, heavy, twisted, and bent
branches, which are given off near the ground and often hang low, giving the
appearance of an old apple tree. Young trees, with their low, thick trunks, surmounted
by pyramidal crowns of rather straight rising branches, have a very
different aspect. As a rule, the single-leaf pine does not exceed 25 feet in height
and from 12 to 15 inches in diameter. In protected and otherwise favorable
situations it may reach a height of from 35 to 50 feet, but it is characteristically
a low, sprawling tree. Bark of young trunks is smooth and dull gray,
while that of old trunks is roughly and irregularly furrowed, nearly an inch
thick, aid with thin, close, dark brown, sometimes reddish brown, scales. Tha
general color of the foliage is pale yellow-green with a w-hitish tinge. The
single (or very occasionally double) leaves are stiff, curved toward the branch,
prickly, and from about 1a to 24 inches long-generally about 14 inches long
(fig. 9). A season's growth of leaves remains on the tree about five years; not
rarely leaves persist ten to twelve years. A striking peculiarity of seedling
trees is that they continue to produce only primary leaves for six or seven
years, after which they put forth normal foliage. Cones (fig. 9) are matured
in August of the second season; they shed their seeds, which leave their thin,
narrow wings attached to the cone scales, within about a month afterward,
when the tips of the scales become shiny and a deep russet-brown. Most of
the empty cones fall from the trees during the winter or spring. The seeds
(fig. 9, c), are dark chocolate brown, with dull yellowish areas; extensively
gathered by Indians for food. Seed leaves, 7 to 10. Wood, yellowish brown,
very fine-grained, moderately light, and very brittle.
LONGEVITY.-An exceedingly slow-growing tree, reaching an age of from 100 to
225 years. Further records of longevity are required.
RA NG E.
Desert regions of Utah, Nevada, Arizona, southeastern California, and northern Lower
California.
CALIFORNIA.-In southern Sierras, on east slopes at about 6,000 to 8.000 feet from
Loyalton, Sierra County (extreme northern limit probably still undetermined) and
Markleeville Creek (east side of Sierras) southward to vicinity of Walker Pass, where