I have spent a good deal of time, trying to determine their age, but on account of dry not which honeycombs most of the old ones, I never got a complete count of the largest. Some are undoubtedly more than two thousand years old; for though on good moraine soil they grow about as fast as oaks, on bare pavements and smoothly glaciated overswept granite ridges in the dome region they grow extremely slowly. One on the Starr King ridge, only two feet eleven inches in diameter, was eleven hundred and forty years old. Another on the same ridge, only one foot seven and a half inches in diameter, had reached the age of eight hundred and thirty-four years. The first fifteen inches from the bark of a medium-sized tree-six feet in diameter-on the north Tenaya pavement had eight hundred and fifty-nine layers of wood, or fifty-seven to the inch. Beyond this the count was stopped by dry rot and scars of old wounds. The largest I examined was thirty-three feet in girth, or nearly ten in diameter; and though I failed to get anything like a complete count, I learned enough from this and many other specimens to convince me that most of the trees eight to ten feet thick standing on pavements are more than twenty centuries of age rather than less. Barring accidents, for all I can see, they would live forever. When killed, they waste out of existence about as slowly as granite. Even when overthrown by avalanches, after standing so long, they refuse to lie at rest, leaning stubbornly on their big elbows as if anxious to rise, and while a single root holds to the rock putting forth fresh leaves with a grim never-say-die and never-lie-down expression.
As the juniper is the most stubborn and unshakable of trees, the mountain hemlock (Tsuga Mertensiana) is the most graceful and pliant and sensitive, responding to the slightest touches of the wind. Until it reaches a height of fifty or sixty feet it is sumptuously clothed down to the ground with drooping branches, which are divided into countless delicate waving sprays, grouped and arranged in most indescribably beautiful ways, and profusely sprinkled with handsome brown cones. The flowers also are peculiarly beautiful and effective; the pistillate very dark rich purple; the estimate blue of so fine and pure a tone that the best azure of the high sky seems to be condensed in them.
Though apparently the most delicate and feminine of all the mountain trees, it grows best where the snow lies deepest, at an elevation of from nine thousand to nine thousand five hundred feet, in hollows on the northern slopes of mountains and ridges. But under all circumstances and conditions of weather and soil, sheltered from the main currents of the winds or in blank exposure to them, well fed or starved, it is always singularly graceful in habit. Even at its highest limit in the park, ten thousand five hundred feet above the sea on exposed ridgetops, where it crouches and huddles close together in low thickets like those of the dwarf pine, it still contrives to put forth its sprays and branches in forms of irrepressible beauty, while on moist well-drained moraines it displays a perfectly tropical luxuriance of foliage, flower, and fruit.
In the first winter storms the snow is oftentimes soft, and lodges in the dense leafy branches, pressing them down against the trunk, and the slender drooping axis bends lower and lower as the load increases, until the top touches the ground and an ornamental arch is made. Then, as storm succeeds storm and snow is heaped on snow, the whole tree is at last buried, not again to see the light or move leaf or limb until set free by the spring thaws in June or July. Not the young saplings only are thus carefully covered and put to sleep in the whitest of white beds for five or six months of the year, but trees thirty and forty feet high. From April to May, then the snow is compacted, you may ride over the prostrate groves without seeing a single branch or leaf of them. In the autumn they are full of merry life, when Clark crows, squirrels, and chipmunks are gathering the abundant crop of seeds while the deer rest beneath the thick concealing branches. The finest grove in the park is near Mount Conness, and the trail from the Tuolumne soda springs to the mountain runs through it. Many of the trees in this grove are three to four or five feet in diameter and about a hundred feet high.
The mountain hemlock is widely distributed from near the south extremity of the high Sierra northward along the Cascade Mountains of Oregon and Washington and the coast ranges of British Columbia to Alaska, where it was first discovered in 1827. Its northmost limit, so far as I have observed, is in the icy fiords of Prince William's Sound in latitude 61, where it forms are forests at the level of the sea, growing tall and majestic on the banks of the great glaciers, waving in accord with the mountain winds and the thunder of the falling icebergs. Here as in the Sierra it is ineffably beautiful, the very loveliest evergreen in America.
Of the round-headed dicotyledonous trees in the park the most influential are the black and goldcup oaks. They occur in some parts of the main forest belt, scattered among the big pines like a heavier chaparral, but form extensive groves and reach perfect development only in the Yosemite valleys and flats of the main cañons. The California black oak (Quercus Californica) is one of the largest and most beautiful of the Western oaks, attaining under favorable conditions a height of sixty to a hundred feet, with a trunk three to seven feet in diameter, wide-spreading picturesque branches, and smooth lively green foliage handsomely scalloped, purple in the spring, yellow and red in autumn. It grows best in sunny open groves on ground covered with ferns, chokecherry, brier rose, rubus, mints, goldenrods, etc. Few, if any, of the famous oak groves of Europe, however extensive, surpass these in the size and strength and bright, airy beauty of the trees, the color and fragrance of the vegetation beneath them, the quality of the light that fills their leafy arches, and in the grandeur of the surrounding scenery. The finest grove in the park is in one of the little Yosemite valleys of the Tuolumne Cañon, a few miles above Hetch-Hetchy.
The mountain live-oak, or goldcup oak (Quercus chrysolepis), forms extensive groves on earthquake and avalanche taluses and terraces in cañons and Yosemite valleys, from about three to five thousand feet above the sea. In tough, sturdy, unwedgeable strength this is the oak of oaks. In general appearance it resembles the great live-oak of the Southern states. It has pale gray dark, a short, uneven, heavily buttressed trunk which usually divides a few feet above the ground into strong wide-reaching limbs, forming noble arches, and ending in an intricate maze of small branches and sprays, the outer ones frequently drooping in long tresses to the ground like those of the weeping willow, covered with small simple polished leaves, making a canopy broad and bossy, on which the sunshine falls in glorious brightness. The acorn cups are shallow, thick-walled, and covered with yellow fuzzy dust. The flowers appear in May and June with a profusion of pollened tresses, followed by the bronze-colored young leaves.
No tree in the park is a better measure of altitude. In cañons, at an elevation of four thousand, feet you may easily find a tree six or eight feet in diameter; and at the head of a side cañon, three thousand feet higher, up which you can climb in less than two hours, you find the knotty giant dwarfed to a slender shrub, with leaves like those of huckleberry bushes, still bearing acorns, and seemingly contented, forming dense patches of chaparral, on the top of which you may make your bed and sleep softly like a Highlander in heather. About a thousand feet higher it is still smaller, making fringes about a foot high around boulders and along seams in pavements and the brows of cañons, giving hand-holds here and there on cliffs hard to climb. The largest I have measured were from twenty-five to twenty-seven feet in girth, fifty to sixty feet high, and the spread of the limbs was about double the height.
The principal riverside trees are poplar, alder, willow, broad-leaved maple, and Nuttall's flowering dogwood. The poplar (Populus trichocarpa), often called balm of Gilead from the gum on its buds, is a tall, stately tree, towering above its companions and gracefully embowering the banks of the main streams at an elevation of about four thousand feet. 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.
The flowering dogwood is brighter still in these brooding days, for every branch of its broad head is then a brilliant crimson flame. In the spring, when the streams are in flood, it is the whitest of trees, white as a snow bank with its magnificent flowers four to eight inches in width, making a wonderful show, and drawing swarms of moths and butterflies.
The broad-leaved maple is usually found in the coolest boulder-choked cañons, where the streams are gray and white with foam, over which it spreads its branches in beautiful arches from bank to bank, forming leafy tunnels full of soft green light and spray,—favorite homes of the water ousel. Around the glacier lakes, two or three thousand feet higher, the common aspen grows in fringing lines and groves which are brilliantly colored in autumn, reminding you of the color glory of the Eastern woods.
Scattered here and there or in groves the botanist will find a few other trees, mostly small,—the mountain mahogany, cherry, chestnut-oak, laurel, and nutmeg. The California nutmeg (Tumion Californicum) is a handsome evergreen, belonging to the yew family, with pale bark, prickly leaves, fruit like a green-gage plum, and seed like a nutmeg. One of the best groves of it in the park is at the Cascades below Yosemite.