THE TREELESS MOUNTAIN TOPS

On the higher mountains of North America above the upper limit at which trees are able to grow there are picturesque regions carpeted and garlanded in late spring and summer with lovely flowers, the indescribable charms of which are only known to those who rejoice in climbing rugged peaks and in following the trails of the mountain-goat along sharp-crested ridges. The gorgeous blossoms of these roof-gardens of the world are much the same on all high mountains in temperate latitudes, but from having become first widely known to civilized man on the mountains of Switzerland, are generally termed alpine flowers. The most attractive features of an alpine flora, which springs into bloom as soon as the snow melts and forms a rapidly widening belt of colour as the margins of the snow-fields recede higher and higher, is the great profusion of brilliantly coloured blossoms. No sooner does the snow of winter melt than the moist ground becomes enamelled in brilliant colours on account of the springing up and quick blossoming of millions of hardy plants. The growing season on mountain heights is short, but the sun's energy is there more intense and the hours of light each day longer than in the valleys below, and the plants adapted to such conditions pass through their annual circle of changes from sprouting seed to mature fruit with remarkable rapidity. In many instances the mountain-climber finds beautiful lilies unfolding their sun-dyed blossoms at the bottom of well-like depressions in lingering snow-banks. The gleaming mountain-peaks when seen from afar are said to be crowned with snow, but the mountaineer rejoices in the knowledge that their cold diadems are wreathed and festooned about their lower margins with lovely blossoms. Many mountains less ambitious than their neighbours have the garlands without the crown. An alpine flora is present on the Pacific mountains from Mexico northward to Alaska. Like the "timber-line" and the "snow-line," the intermediate belt of profusely flowering herbaceous plants descends lower and lower with decrease in latitude; on the great volcanic

cones of Mexico it has an elevation of over 15,000 feet; on the Sierra Nevada the greatest wealth of flowers occurs at about 12,000 feet; on Mount Rainier widely extended gardens resplendent with rainbow tints occur at 7,000 to 8,000 feet; and about the foot-hills near Mount St. Elias, at an elevation of 2,500 feet or less above the sea, every knoll and island-like area in the vast ice-fields is so densely overgrown with brilliantly flowered plants that one has to part the rank growths with his hands and press them aside with his alpenstick in order to force a way through the fields of bloom. Admirers of nature's loveliness who have not climbed to aspiring heights will find a new and beautiful world in the public alpine garden on the summit and about the snow-fields of the higher portions of the Pacific mountains, where no sign-boards forbid entry and no fences obstruct the way. In these regions nearest the sun and stars there are few, if any, plants of utility to man, but marvellous beauty and lavish profusion fill the foreground in every view. These glorious mountain heights have their use, however, although as yet known to but few; rest and recreation amid scenes at the same time novel and most inspiring may there be found by the toilers in our crowded cities.

Among the Atlantic mountains only a few summits attain a sufficient elevation to claim a wreath of alpine flowers. Something of the nature of the gorgeous fields of bloom about the great peaks of the Pacific mountains is suggested on the treeless summits of the White Mountains, but although classed by botanists among alpine floras, the plants growing there fail to give a true idea of the display characteristic of the mountains which make a nearer approach to the lower limit of perennial snow. In the southern Appalachians the absence of a luxuriant alpine flora is perhaps more than counterbalanced by the profusion of rhododendrons, azaleas, and laurels.

One instructive lesson suggested by this hasty glance at the plant life of North America is furnished by the quick response that vegetation gives to conditions of environment.

Throughout the greater divisions of the forest, prairies, grass-covered plains and valleys, and flower-decked mountain heights there are constant variations from locality to locality in the plant life to meet seemingly obscure or but slight changes in the conditions of temperature, humidity, exposure to sunlight, soil composition, soil texture, etc.; and besides there is a never-ceasing struggle for existence among the plants themselves which leads to important modifications of a flora. These changes occur from locality to locality, frequently within a short radius, but more than this, the resultant of the various modifying conditions on which plant life depends are not constant even for a given locality. The study of extinct floras has shown that during the preceding ages in the earth's history marvellous changes in the plants of many regions, and, in fact, of the entire earth's surface, have taken place. The distinct impressions of palm-leaves, for example, are commonly found in the rocks of the Cascade Mountains, where spruces, firs, and cedars now dominate the landscape. Still more striking is the fact that even treeless Greenland and the largely ice-covered islands of the arctic archipelago were formerly clothed with forests as luxuriant and varied as those now growing in the southern Appalachian region. Although the migrations of existing forests during the few centuries of which we have historic records have been too slow to be appreciated by man, yet it is safe to conclude that changes similar to, and in fact a continuation of, those known by geologists to have taken place in the distribution of the vegetation of the continent since the Tertiary period are still in progress. With far-reaching and exceedingly slow changes in climatic conditions and in elevation above the sea due to upheaval and denudation, the plants of our forests, prairies, and mountainsides, are being moved here and there, in ever-changing combinations. Nature thus secures a rotation in the vegetation of a region, as the careful husbandman varies his crops from year to year. The suggestion in this connection furnished by geologists is that we are living in a spring-time following the great winter, known as the Glacial epoch, and that the tropical,

temperate, and subarctic forests are migrating northward in an orderly march, and each in turn ascending higher and higher on the more lofty mountains.

LITERATURE