A year among the trees

by Wilson Flagg

I have not much faith in the science of ignorant men; for the foundations of all knowledge are laid in books; and those only who have read and studied much can possess any considerable store of wisdom. But there are philosophers among laboring swains, whose quaint observations and solutions of nature’s problems are sometimes worthy of record. With these men of untutored genius I have had considerable intercourse, and hence I oftener quote them than the learned and distinguished, whom I have rarely met. The ignorant, from want of knowledge, are always theorists; but genius affords its possessor, how small soever his acquisitions, some glimpses of truth which may be entirely hidden from the mere pedant in science. My philosophic friend, a man of genius born to the plough, entertained a theory in regard to the atmosphere, which, though not strictly philosophical, is so ingenious and suggestive that I have thought an account of it a good introduction to this essay.

My friend, when explaining his views, alluded to the well-known fact that plants growing in an aquarium keep the water supplied with atmospheric air—not with simple oxygen, but with oxygen chemically combined with nitrogen—by some vital process that takes place in the leaves of plants. As the lungs of animals decompose the air which they inspire, and breathe out carbonic-acid gas, plants in their turn decompose this deleterious gas, and breathe out pure atmospheric air. His theory is that the atmosphere is entirely the product of vegetation, and that nature has no other means of composing it; that it is not simply a chemical, but a vital product; and that its production, like its preservation, depends entirely on plants, and would be impossible without their agency. But as all plants united are not equal in bulk to the trees, it may be truly averred that any series of operations or accidents that should deprive the earth entirely of its forests would leave the atmosphere without a source for its regeneration.

The use of the foliage of trees in renovating the atmosphere is not, I believe, denied by any man of science. This theory has been proved to be true by experiments in vital chemistry. The same chemical appropriation of gases and transpiration of oxygen is performed by all classes of vegetables; but any work in the economy of nature assigned to vegetation is the most effectually accomplished by trees. The property of foliage that requires carbonic-acid gas for its breathing purposes, and causes it to give out oxygen, is of vital importance; and it is hardly to be doubted that a close room well lighted by the sun would sustain its healthful atmosphere a longer time, if it were filled with plants in leaf, but not in flower, and occupied by breathing animals, than if the animals occupied it without the plants.

But there is another function performed by the foliage of trees and herbs in which no chemical process is involved,—that of exhaling moisture into the atmosphere after it has been absorbed by the roots. Hence the humidity of this element is greatly dependent on foliage. A few simple experiments will show how much more rapidly and abundantly this evaporation takes place when the soil is covered with growing plants than when the surface is bare. Take two teacups of equal size and fill them with water. Place them on a table, and insert into one of them cuttings of growing plants with their leaves, and let the other stand with water only. In a few hours the water will disappear from the cup containing the plants, while that in the other cup will not be sensibly diminished. Indeed, there is reason to believe that gallons of water might be evaporated into the air by keeping the cup containing the cuttings always full, before the single gill contained in the other cup would disappear. If a few cuttings will evaporate a half-pint of water in twelve hours, we can imagine the vast quantity constantly exhaled into the atmosphere by a single tree. The largest steam-boiler in use, kept constantly boiling, would not probably evaporate more water than one large elm in the same time.

We may judge, from our experiment with the cuttings, that a vastly greater proportion of moisture would be exhaled into the atmosphere from any given surface of ground when covered with vegetation, than from the same amount of uncovered surface, or even of standing water. Plants are indeed the most important existing agents of nature for conveying the moisture of the earth into the air. The quantity of transpiring foliage from a dense assemblage of trees must be immense. The evaporation of water from the vast ocean itself is probably small compared with that from the land which it surrounds. And there is reason to believe that the water evaporated from the ocean would not produce rain enough to sustain vegetation, if by any accident every continent and island were deprived of its trees. The whole earth would soon become a desert. I would remark, in this place, that trees are the agents by which the superfluous waters of the ocean, as they are supplied by rivers emptying into it, are restored to the atmosphere and thence again to the surface of the earth. Trees pump up from great depths the waters as they ooze into the soil from millions of subterranean ducts ramifying in all directions from the bed of the ocean.

LEAF OF HOLLY.

THE HOLLY.

As the hawthorn is consecrated to vernal festivities, the Holly is sacred to those of winter, and the yew to those attending the burial of the dead. In Europe, from the earliest ages, the Holly has been employed for the decoration of churches during Christmas. The poets have made it a symbol of forethought, because its leaves are saved from the browsing of animals by the thorns that surround them; and the berries, concealed by its prickly foliage, are preserved for the use of the winter birds. The Holly is found only in the southern parts of New England. In Connecticut it is common, and in the Middle and Southern States it is a tree of third magnitude. The leaves of the Holly are slightly sinuate or scalloped, and furnished at each point with short spines. It not only retains its foliage in the winter, but it loses none of that brilliancy of verdure that distinguishes it at other seasons.

There seems to be no very notable difference between the American and European Holly. Selby says of the latter: “The size which the Holly frequently attains in a state of nature, as well as when under cultivation, its beauty and importance in forest and woodland scenery, either as a secondary tree or merely as an underwood shrub, justify our placing it among the British forest trees of the second rank.” He adds: “As an ornamental evergreen, whether in the form of a tree or as an undergrowth, the Holly is one of the most beautiful we possess. The deep green glittering foliage contrasts admirably with the rich coral hue of its berries.”