THE LONGEVITY OF TREES.
IN the vegetable world, limits of growth and life are strangely diversified. Multitudes of forms mature and perish in a few days or hours; while others, whose beginning was in a remote antiquity, have survived the habitual period of their kind, and still enjoy the luxuriance of their prime. Some species of unicellular plants are so minute that millions occur in the bulk of a cubic inch, and a flowering plant is described by Humboldt, which, when fully developed, is not more than three-tenths of an inch in height. On the other hand, we have the great Sequoia, whose mass is expressed by hundreds of tons, and specimens of the Eucalyptus, growing in the gulches of Australia, surpass in height the dome of St. Peter’s. Some of the Fungi mature between the setting and rising of the sun, while the oak at our door, which awakens the memories of our childhood, has not perceptibly changed in bulk in half a century. Trees grow more slowly as they increase in age. Nevertheless, it is certain that growth continues while they continue to live. The development of foliage implies interstitial activity and organization of new material. In its vital processes there is little expenditure of force or waste of substance. Its functions are essentially constructive, and its growth and age are apparently without limits, excepting such as arise from surrounding conditions. Thus many trees represent centuries, and have a permanence that is astonishing and sublime. Travellers stand awe-struck before the monuments which for forty centuries have kept watch by the Nile, but the oldest of these may not antedate the famous dragon-tree of Teneriffe. It is not surprising that the ancients considered trees “immortal,” or, as “old as Time.” But, if the life of the tree is continuous, its leaves—the organs of its growth—have their periods of decay, and are types of mortality. The life of man is likened to the “leaf that perishes.” In an animal, the vital processes are carried on by a single set of organs, the impairment of which limits the period of its life. With the tree, decay of the organs is followed by constant renovation, and the foliage which covers it the present summer is as new and as young as that which adorned it a hundred or a thousand years ago. . . . The great living monuments of the vegetable kingdom. Fixed to a single spot, the tree is what it is because of the forces which act upon it. It is a monument of accumulated and concentrated force. Transmuted sunlight is in all its fibres, and who shall estimate the dynamic work which has been expended in its structure? Dr. Draper observes that “the beat of a pendulum occupies a second of time; divide that period into a million of equal parts, then divide each of these brief periods into a million of other equal parts, a wave of yellow light daring one of the last small intervals has vibrated 535 times. Yet that yellow light has been the chief instrument in building the tree.” In the delicate texture of its leaves it has overcome molecular force; it has beaten asunder the elements of an invisible gas, and inaugurated a new arrangement of atoms. The old dragon-tree represents forty centuries of this dynamic work—a sublime monument reared without toil by the silent forces of Nature! In the outer air it has awakened every note of sound, from the softest monotone to the rhythmic roar of the tempest; but in its inner chambers has been a murmur and music of life in the ceaseless movement of fluids and marshalling of atoms, as one by one they take their place in the molecular dance, which eludes the dull sense of hearing, and becomes obvious only in results. The veil which hides these ultimate processes of life has not yet been lifted, and Science pauses in waiting before it, but only waits.
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“Scientists have known for decades that microphones can pick up the sounds that trees make. Now, scientists may have found the key to understanding these particular cries . . . In the lab, a team of French scientists has captured the ultrasonic noise made by bubbles forming inside water-stressed trees . . . .”
‘“Man is senescent, that is to say is programmed to die, but a plane tree is not,” says French botanist Francis Hallé. After its leaves have fallen, life begins again in the spring and the tree recovers its youthful genomes. If it is not subjected to accidents, diseases or humans, the plane tree could live for centuries . . . .’