The most influential of the Valley trees is the yellow pine (Pinus ponderosa). It attains its noblest dimensions on beds of water-washed, coarsely-stratified moraine material, between the talus slopes and meadows, dry on the surface, well-watered below and where not too closely assembled in groves the branches reach nearly to the ground, forming grand spires 200 to 220 feet in height. The largest that I have measured is standing alone almost opposite the Sentinel Rock, or a little to the westward of it. It is a little over eight feet in diameter and about 220 feet high. Climbing these grand trees, especially when they are waving and singing in worship in wind-storms, is a glorious experience. Ascending from the lowest branch to the topmost is like stepping up stairs through a blaze of white light, every needle thrilling and shining as if with religious ecstasy.
Unfortunately there are but few sugar pines in the Valley, though in the Kingβs yosemite they are in glorious abundance. The incense cedar (Libocedrus decurrens) with cinnamon-colored bark and yellow-green foliage is one of the most interesting of the Yosemite trees. Some of them are 150 feet high, from six to ten feet in diameter, and they are never out of sight as you saunter among the yellow pines. Their bright brown shafts and towers of flat, frondlike branches make a striking feature of the landscapes throughout all the seasons. In midwinter, when most of the other trees are asleep, this cedar puts forth its flowers in millions,βthe pistillate pale green and inconspicuous, but the staminate bright yellow, tingeing all the branches and making the trees as they stand in the snow look like gigantic goldenrods. The branches, outspread in flat plumes and, beautifully fronded, sweep gracefully downward and outward, except those near the top, which aspire; the lowest, especially in youth and middle age, droop to the ground, overlapping one another, shedding off rain and snow like shingles, and making fine tents for birds and campers. This tree frequently lives more than a thousand years and is well worthy its place beside the great pines and the Douglas spruce.
The two largest specimens I know of the Douglas spruce, about eight feet in diameter, are growing at the foot of the Liberty Cap near the Nevada Fall, and on the terminal moraine of the small residual glacier that lingered in the shady Illilouette CaΓ±on.
After the conifers, the most important of the Yosemite trees are the oaks, two species; the California live-oak (Quercus agrifolia), with black trunks, reaching a thickness of from four to nearly seven feet, wide spreading branches and bright deeply-scalloped leaves. It occupies the greater part of the broad sandy flats of the upper end of the Valley, and is the species that yields the acorns so highly prized by the Indians and woodpeckers.
The other species is the mountain live-oak, or goldcup oak (Quercus chrysolepis), a sturdy mountaineer of a tree, growing mostly on the earthquake taluses and benches of the sunny north wall of the Valley. In tough, unwedgeable, knotty strength, it is the oak of oaks, a magnificent tree.
The largest and most picturesque specimen in the Valley is near the foot of the Tenaya Fall, a romantic spot seldom seen on account of the rough trouble of getting to it. It is planted on three huge boulders and yet manages to draw sufficient moisture and food from this craggy soil to maintain itself in good health. It is twenty feet in circumference, measured above a large branch between three and four feet in diameter that has been broken off. The main knotty trunk seems to be made up of craggy granite boulders like those on which it stands, being about the same color as the mossy, lichened boulders and about as rough. Two moss-lined caves near the ground open back into the trunk, one on the north side, the other on the west, forming picturesque, romantic seats. The largest of the main branches is eighteen feet and nine inches in circumference, and some of the long pendulous branchlets droop over the stream at the foot of the fall where it is gray with spray. The leaves are glossy yellow-green, ever in motion from the wind from the fall. It is a fine place to dream in, with falls, cascades, cool rocks lined with hypnum three inches thick; shaded with maple, dogwood, alder, willow; grand clumps of lady-ferns where no hand may touch them; light filtering through translucent leaves; oaks fifty feet high; lilies eight feet high in a filled lake basin near by, and the finest libocedrus groves and tallest ferns and goldenrods.
In the main river caΓ±on below the Vernal Fall and on the shady south side of the Valley there are a few groves of the silver fir (Abies concolor), and superb forests of the magnificent species round the rim of the Valley.
On the tops of the domes is found the sturdy, storm-enduring red cedar (Juniperus occidentalis). It never makes anything like a forest here, but stands out separate and independent in the wind, clinging by slight joints to the rock, with scarce a handful of soil in sight of it, seeming to depend chiefly on snow and air for nourishment, and yet it has maintained tough health on this diet for two thousand years or more. The largest hereabouts are from five to six feet in diameter and fifty feet in height.
The principal river-side trees are poplar, alder, willow, broad-leaved maple, and Nuttallβs flowering dogwood. The poplar (Populus trichocarpa), often called balm-of-Gilead from the gum on its buds, is a tall tree, towering above its companions and gracefully embowering the banks of the river. Its abundant foliage turns bright yellow in the fall, and the Indian-summer sunshine sifts through it in delightful tones over the slow-gliding waters when they are at their lowest ebb.
Some of the involucres of the flowering dogwood measure six to eight inches in diameter, and the whole tree when in flower looks as if covered with snow. In the spring when the streams are in flood it is the whitest of trees. In Indian summer the leaves become bright crimson, making a still grander show than the flowers.
The broad-leaved maple and mountain maple are found mostly in the cool caΓ±ons at the head of the Valley, spreading their branches in beautiful arches over the foaming streams.
Scattered here and there are a few other trees, mostly smallβthe mountain mahogany, cherry, chestnut-oak, and laurel. The California nutmeg (Torreya californica), a handsome evergreen belonging to the yew family, forms small groves near the cascades a mile or two below the foot of the Valley.
For the use of the ever-increasing number of Yosemite visitors who make extensive excursions into the mountains beyond the Valley, a sketch of the forest trees in general will probably be found useful. The different species are arranged in zones and sections, which brings the forest as a whole within the comprehension of every observer. These species are always found as controlled by the climates of different elevations, by soil and by the comparative strength of each species in taking and holding possession of the ground; and so appreciable are these relations the traveler need never be at a loss in determining within a few hundred feet his elevation above sea level by the trees alone; for, notwithstanding some of the species range upward for several thousand feet and all pass one another more or less, yet even those species possessing the greatest vertical range are available in measuring the elevation; inasmuch as they take on new forms corresponding with variations in altitude. Entering the lower fringe of the forest composed of Douglas oaks and Sabine pines, the trees grow so far apart that not one-twentieth of the surface of the ground is in shade at noon. After advancing fifteen or twenty miles towards Yosemite and making an ascent of from two to three thousand feet you reach the lower margin of the main pine belt, composed of great sugar pine, yellow pine, incense cedar and sequoia. Next you come to the magnificent silver-fir belt and lastly to the upper pine belt, which sweep up to the feet of the summit peaks in a dwarfed fringe, to a height of from ten to twelve thousand feet. That this general order of distribution depends on climate as affected by height above the sea, is seen at once, but there are other harmonies that become manifest only after observation and study. One of the most interesting of these is the arrangement of the forest in long curving bands, braided together into lace-like patterns in some places and out-spread in charming variety. The key to these striking arrangements is the system of ancient glaciers; where they flowed the trees followed, tracing their courses along the sides of caΓ±ons, over ridges, and high plateaus. The cedar of Lebanon, said Sir Joseph Hooker, occurs upon one of the moraines of an ancient glacier. All the forests of the Sierra are growing upon moraines, but moraines vanish like the glaciers that make them. Every storm that falls upon them wastes them, carrying away their decaying, disintegrating material into new formations, until they are no longer recognizable without tracing their transitional forms down the Range from those still in process of formation in some places through those that are more and more ancient and more obscured by vegetation and all kinds of post-glacial weathering. It appears, therefore, that the Sierra forests indicate the extent and positions of ancient moraines as well as they do belts of climate.
One will have no difficulty in knowing the Nut Pine (Pinus Sabiniana), for it is the first conifer met in ascending the Range from the west, springing up here and there among Douglas oaks and thickets of ceanothus and manzanita; its extreme upper limit being about 4000 feet above the sea, its lower about from 500 to 800 feet. It is remarkable for its loose, airy, wide-branching habit and thin gray foliage. Full-grown specimens are from forty to fifty feet in height and from two to three feet in diameter. The trunk usually divides into three or four main branches about fifteen or twenty feet from the ground that, after bearing away from one another, shoot straight up and form separate summits. Their slender, grayish needles are from eight to twelve inches long, and inclined to droop, contrasting with the rigid, dark-colored trunk and branches. No other tree of my acquaintance so substantial in its body has foliage so thin and pervious to the light. The cones are from five to eight inches long and about as large in thickness; rich chocolate-brown in color and protected by strong, down-curving nooks which terminate the scales. Nevertheless the little Douglas Squirrel can open them. Indians climb the trees like bears and beat off the cones or recklessly cut off the more fruitful branches with hatchets, while the squaws gather and roast them until the scales open sufficiently to allow the hard-shell seeds to be beaten out. The curious little Pinus attenuata is found at an elevation of from 1500 to 3000 feet, growing in close groves and belts. It is exceedingly slender and graceful, although trees that chance to stand alone send out very long, curved branches, making a striking contrast to the ordinary grove form. The foliage is of the same peculiar gray-green color as that of the nut pine, and is worn about as loosely, so that the body of the tree is scarcely obscured by it. At the age of seven or eight years it begins to bear cones in whorls on the main axis, and as they never fall off, the trunk is soon picturesquely dotted with them. Branches also soon become fruitful. The average size of the tree is about thirty or forty feet in height and twelve to fourteen inches in diameter. The cones are about four inches long and covered with a sort of varnish and gum, rendering them impervious to moisture.
No observer can fail to notice the admirable adaptation of this curious pine to the fire-swept regions where alone it is found. After a running fire has scorched and killed it the cones open and the ground beneath it is then sown broadcast with all the seeds ripened during its whole life. Then up spring a crowd of bright, hopeful seedlings, giving beauty for ashes in lavish abundance.