CHAPTER VII.

FLORA OF THE YELLOWSTONE.

The most conspicuous feature of the Park flora is the wide extent of forest growth which covers some eighty-four per cent of its area. This is the more noticeable because the surrounding country below the mountains is practically treeless. The Park forests consist almost exclusively of pine and fir. The trees are generally tall and slender and of little use for lumber. They are usually unattractive in appearance, although in some places among the mountains the spruce and fir attain a size, form and hue of foliage that are exceedingly beautiful.

Among the several species may be noted the following:

Black pine (_Pinus Murrayana_) so called from the dark hue of its foliage when seen in dense bodies.

Red fir (_Pseudotsuga Douglasii_) the largest variety in the Park, sometimes attaining a diameter of five feet.

Balsam (_Abies subalpina_). It flourishes near the snow fields and is the beauty of the forest.

Spruce (_Pinus Engelmanni_). Like the preceding it flourishes at high altitudes. It is tall and slender, and is good for lumber.

Red cedar (_Juniperus virginiana_) is found to a limited extent.

Poplar or aspen (_Populus tremuloides_) flourishes among the sheltered foot-hills.

Dwarf maple is occasionally found.

Willow thickets abound in great abundance.

Of these varieties the first is found more abundantly than all the others combined. In many places it has fallen down and strews the country to such an extent as to be absolutely impassable on horseback. There is very little timber of marketable value, and at first thought it would seem that nature has here lavished her energies in a most wasteful manner.

But the great value of these forest growths, is their agency in the conservation of a water supply for the surrounding country. A glance at the map will show that the Park is in the midst of a vast arid region extending far into the surrounding states. The reclamation of these desert wastes, and their conversion into productive lands, can be accomplished by irrigation alone, and for this purpose the abundant streams which descend from the mountains are the indispensable water supply.

From the summit of the Grand Teton, the range of vision covers probably the most remarkable group of river sources upon the earth. To the north rises the Missouri which flows three thousand miles through Montana, the Dakotas, Iowa, Nebraska, Kansas and Missouri. To the east rises the Yellowstone, which, after leaving the Park, flows four hundred miles through southern and eastern Montana until it unites with the Missouri. From the eastern foot-hills of the Absaroka and Shoshone Ranges flow the Wind and Big Horn Rivers through the extensive valleys of the same names in Wyoming and Montana. Southwardly, across the Wind River Range rises the Platte which flows eastward eight hundred miles through Wyoming and Nebraska. From the west flank of these mountains issue the tributaries of the Green River (afterward the Colorado) which flows through Wyoming, Utah and Arizona into the Gulf of California. Finally, interlaced with the sources of the Yellowstone, and the Missouri, are those of the Snake River which flows through Wyoming, Idaho and Washington into the Columbia, and thus reaches the Pacific.

Not only do these streams rise in this limited area; they derive from it most of their waters. In the arid lowlands they receive but slight accessions, and often actually shrink under evaporation. It is therefore from a relatively small tract of country that the future water supply must come for portions of ten states in the great arid belt of the west.

The conditions which nature has established around this remarkable fountain-head are admirably adapted for the creation and maintenance of an unlimited water supply. Over an area of more than 5,000 square miles there prevails an average altitude of perhaps 7,500 feet; sufficient to insure enormous annual snowfalls, but not so great as to prevent their complete melting in summer. But, that they may not melt too rapidly, the whole region is covered with a thick forest growth cutting off the intense rays of the summer sun, and covering the ground with a vegetable mold through which the surface waters filter but slowly. It is a conservative estimate, based upon observations in connection with road work in the Park, that these forests prolong the melting of the snows from four to six weeks. This condition greatly lessens the liability to sudden floods, and maintains a generous supply of water far into the summer.

It has been estimated[AW] that from the Park alone, at low water, there flows per second 4,000 cubic feet of water. If the time ever comes when this supply is so far used as to threaten exhaustion, there will be found in the basin of Yellowstone Lake the most perfect facilities in the world for the construction of an artificial reservoir of almost limitless capacity at a comparatively insignificant cost. A dam could be thrown across the gorge at the first rapids in the Yellowstone below the Lake, and without injuring the natural condition of that region, could easily be made to quadruple the present capacity of the Lake.

[AW] By Dr. William Hallock, United States Geological Survey.

The Park with its contiguous area thus presents magnificent possibilities in the development of the surrounding country--possibilities of which its founders little dreamed, but which they unconsciously foreshadowed when they declared that this region should be forever set apart for the "benefit" as well as for the "enjoyment" of the people.

Besides its wealth of trees, the Park produces other interesting flora. Interspersed among the forests and ornamenting the open glades are flowers and shrubs in endless profusion. We quote from the description of one of the early visitors:

"The choke-cherry, the goose-berry, the buffalo-berry, and black and red currants, are found along the streams and in moist places of the middle and lower altitudes. The meadows and hill-sides are spangled with bright-colored flowers, among which may be noted the bee-larkspur, the columbine, the harebell, the lupine, the evening primrose, the aster, the painted cup, the gentian, and various kinds of euphorbia. It is not uncommon to find daises, buttercups, forget-me-nots, white-ground phlox, and other field flowers flourishing in profusion near the melting snow banks during the month of August. Scarcely a night throughout the year passes without frost, even though the temperature by day is over 80 F., so that all forms of vegetation in the Park grow and bloom under somewhat unusual conditions. Indeed, when ice forms in the water-pails of camping parties during the night, as often happens, and the petals of the flowers become crisp with frost; even then the blooms are not harmed, but thaw out bright and fresh when the hot sun touches them."

The flowers form a most attractive feature of the Park, and give an interesting study of the way in which altitude and temperature affect well known varieties. It is only after a second look that one can trace in the mountain dandelion, huckleberry, and other species a resemblance to those of lower altitudes. The extreme shortness of the season causes vegetation to mature quickly, and before the flush of spring has disappeared from the leaves the palor of autumn makes its appearance.

The mountain grasses are generally abundant in the open country and even in many places among the forests. The writer just quoted says:

"The pasturage on the many open spaces is excellent, the mountain meadows being covered with a mat of nutritious grasses. The predominating variety is the bunch grass, upon which the horses of tourists generally subsist, keeping in good condition without the need of oats. Among other kinds, are the blue joint, fescue, and beard grasses, as well as Alpine timothy, all of which grow luxuriantly."

The early autumns tinge the foliage of the willow parks and other groups of shrubbery with a wealth of color not often seen elsewhere. Even the frost on the grass upon sharp mornings seems to have a peculiar beauty, and one may trace terrestrial rainbows in all the perfection of those set in the sky.