Part 8
We seldom meet anything in the forest more attractive than the groups of Mountain Laurel, which often cover extensive slopes, generally appearing on the edge of a wood, and becoming more scarce as they extend into the interior or wander outwardly from the border. But if we meet with an opening in the wood where the soil is favorable,—some little sunny dell or declivity,—another still more beautiful group opens on the sight, sometimes occupying the whole space. The Mountain Laurel does not constitute the undergrowth of any family of trees, but avails itself of the protection of a wood where it can flourish without being overshadowed by it. In the groups on the outside of the wood, the flowers are usually of a fine rose-color, fading as they are more shaded, until in the deep forest we find them, and the buds likewise, of a pure white. I am not acquainted with another plant that is so sensitive to the action of light upon the color of its flowers. The buds, except in the dark shade, before they expand, are of a deeper red than the flowers, and hardly less beautiful.
The Mountain Laurel delights in wet places, in springy lands on rocky declivities where there is an accumulation of soil, and in openings surrounded by woods, where the land is not a bog, but wet enough to abound in ferns. In such places the Kalmia, with its bright evergreen leaves, forms elegant masses of shrubbery, even when it is not in flower. Indeed, its foliage is hardly less conspicuous than its flowers. I believe the Kalmias are not susceptible of modification by the arts of the florist. Nature has endowed them with a perfection that cannot be improved.
THE LOW LAUREL, OR LAMBKILL.
The low Laurel, or small Kalmia, is plainly one of nature’s favorite productions; for, the wilder and ruder the situation, the more luxuriant is this plant and the more beautiful are its flowers. These are of a deep rose-color, arranged in crowded whorls around the extremities of the branches, with the recent shoot containing a tuft of newly formed leaves surmounting each cluster of flowers. This plant, though not celebrated in horticultural literature or song, is one of the most exquisite productions of nature. Many other shrubs which are more showy are not to be compared with this in the delicate structure of its flowers and in the beauty of their arrangement and colors. Of this species the most beautiful individuals are found on the outer edge of their groups.
There has been much speculation about the supposed poisonous qualities of this plant and its allied species. Nuttall thought its flowers the source of the deleterious honey discovered in the nests of certain wild bees. There is also a general belief that its leaves are poisonous to cattle and flocks. But all positive evidence is wanting to support any of these notions. The idea associated with the name of this species is a vulgar error arising from a corruption of the generic name, from which Lambkill may be thus derived,—Kalmia, Kallamia, Killamia, Killam, Lambkill. There is no other way of explaining the origin of its common English name. I have never been able to discover an authentic account, and have never known an instance of the death of a sheep or a lamb from eating the leaves of this plant. It is an error having its origin in a false etymology; and half the notions that prevail in the world with regard to the medical virtues and other properties of plants have a similar foundation.
It is stated in an English manual of Medical Botany that the brown powder that adheres to the petioles of the different species of Kalmia, Andromeda, and Rhododendron is used by the North American Indians as snuff.
MOTIONS OF TREES.
While Nature, in the forms of trees, in the color of their foliage and the gracefulness of their spray, has displayed a great variety of outline and tinting, and provided a constant entertainment for the sight, she has increased their attractions by endowing them with a different susceptibility to motion from the action of the winds. In their motions we perceive no less variety than in their forms. The different species differ like animals; some being graceful and easy, others stiff and awkward; some calm and intrepid, others nervous and easily agitated. Perhaps with stricter analogy we might compare them to human beings; for we find trees that represent the man of quiet and dignified deportment, also the man of excited manners and rapid gesticulations. Some trees, like the fir, having stiff branches and foliage, move awkwardly backward and forward in the wind, without any separate motions of their leaves. While we admire the symmetrical and stately forms of such trees, we are reminded of men who present a noble personal appearance, accompanied with ungainly manners.
Some trees, having stiff branches with flexible leaves, do not bend to a moderate breeze, but their foliage readily yields to the motion of the wind. This habit is observed in the oak and the ash, in all trees that have a pendulous foliage and upright or horizontal branches. The poplars possess this habit in a remarkable degree, and it is proverbial in the aspen. It is also conspicuous in the common pear-tree and in the small white birch. Other trees, like the American elm, wave their branches gracefully, with but little apparent motion of their leaves. We observe the same habit in the weeping willow, and indeed in all trees with a long and flexible spray. The wind produces by its action on these a general sweeping movement without any rustle. It is easy to observe, when walking in a grove, that the only graceful motions come from trees with drooping branches, because these alone are long and slender.
The very rapid motion of the leaves of the aspen has given origin to some remarkable superstitions. The Highlanders of Scotland believe the wood of this tree to be that of which the holy cross was made, and that its leaves are consequently never allowed to rest. Impressed with the awfulness of the tragedy of the crucifixion, they are constantly indicating to the winds the terrors that agitate them. The small white birch displays considerable of the same motion of the leaves; but we take little notice of it, because they are softer and produce less of a rustling sound. The flickering lights and shadows observed when walking under these trees, on a bright noonday, have always been admired. All these habits awaken our interest in trees and other plants by assimilating them to animated things.
Much of the beauty of the silver poplar comes from its glittering lights, when it presents the green upper surface of its foliage, alternating rapidly with the white silvery surface beneath. This we may readily perceive even in cloudy weather, but in the bright sunshine the contrasts are very brilliant. In all trees, however, we observe this glittering beauty of motion in the sunshine. The under part of leaves being less glossy than the upper part, there is in the assemblage the same tremulous lustre that appears on the rippled surface of a lake by moonlight.
We observe occasionally other motions which I have not described, such as the uniform bending of the whole tree. In a strong current of wind, tall and slender trees especially attract our attention by bending over uniformly like a plume. This habit is often seen in the white birch, a tree that in its usual assemblages takes a plumelike form. When a whole grove of white birches is seen thus bending over in one direction from the action of a brisk wind, they seem like a procession of living forms. In a storm we watch with peculiar interest the bending forms of certain tall elms, such as we often see in clearings, with their heads bowed down almost to the ground by the force of the tempest. It is only the waves of the ocean and the tossing of its billows that can afford us so vivid an impression of the sublimity of a tempest as the violent swaying of a forest and the roaring of the winds among the lofty tree-tops.
The motions of an assemblage of trees cannot be observed except from a stand that permits us to look down upon the surface formed by their summits. We should then perceive that pines and firs, with all the stiffness of their branches, display a great deal of undulating motion. These undulations or wavy movements are particularly graceful in a grove of hemlocks, when they are densely assembled without being crowded. It is remarkable that one of the most graceful of trees belongs to a family which are distinguished by their stiffness and formality. The hemlock, unlike other firs and spruces, has a very flexible spray, with leaves also slightly movable, which are constantly sparkling when agitated by the wind. If we look down from an opposite point, considerably elevated, upon a grove of hemlocks when they are exposed to brisk currents of wind, they display a peculiar undulating movement of the branches and foliage, made more apparent by the glitter of their leaves.
The surface of any assemblage of trees when in motion bears a close resemblance to the waves of the sea. But hemlocks represent its undulations when greatly agitated, without any broken lines upon its surface. Other firs display in their motions harsher angles and a somewhat broken surface of the waves. We see the tops of these trees and their extreme branches awkwardly swaying backwards and forwards, and forming a surface like that of the sea when it is broken by tumultuous waves of a moderate height. The one suggests the idea of tumult and contention; the other, that of life and motion combined with serenity and peace.
THE TULIP-TREE.
The Tulip-tree is pronounced by Dr. Bigelow “one of the noblest trees, both in size and beauty, of the American forest.” It certainly displays the character of immensity,—a quality not necessarily allied with those features we most admire in landscape. It is not very unlike the Canada poplar, and is designated by the name of White Poplar in the Western States. The foliage of this tree has been greatly extolled, but it has the heaviness which is apparent in the foliage of the large-leaved poplars, without its tremulous habit. The leaves, somewhat palmate in their shape, are divided into four pointed lobes, the middle rib ending abruptly, as if the fifth lobe had been cut off. The flowers, which are beautiful, but not showy, are striped with green, yellow, and orange. They do not resemble tulips, however, so much as the flowers of the abutilon and althea.
This tree is known in New England rather as an ornamental tree than as a denizen of the forest. Its native habitats are nearly the same with those of the magnolia, belonging to an allied family. There is not much in the proportions of this tree to attract our admiration, except its size. But its leaves are glossy and of a fine dark green, its branches smooth, and its form symmetrical. It is a tree that agrees very well with dressed grounds, and its general appearance harmonizes with the insipidity of artificial landscape. It is wanting in the picturesque characters of the oak and the tupelo, and inferior in this respect to the common trees of our forest.
THE MAGNOLIA.
The Magnolia, though, excepting one species, a stranger to New England soil, demands some notice. Any one who has never seen the trees of this genus in their native soil can form no correct idea of them. I would not say, however, that they would fall short of his conceptions of their splendor. When I first beheld one of the large magnolias, though it answered to my previous ideas of its magnificence, I thought it a less beautiful tree than the Southern cypress, and less picturesque than the live-oak, the black walnut, and some other trees I saw there. The foliage of the Magnolia is very large and heavy, and so dark as to look gloomy. It is altogether too sombre a tree in the open landscape, and must add to the gloom of any wood which it occupies, without yielding to it any other striking character.
There are several species of Magnolia cultivated in pleasure-grounds, the selection being made from those bearing a profusion of flowers. The only one that grows wild in New England is of small stature, sometimes called the Beaver-tree. It inhabits a swamp near Gloucester, about twenty miles from Boston. This place is its northern boundary. The flowers are of a dull white, without any beauty, but possessed of a very agreeable fragrance, causing them to be in great demand. The Magnolia wood is annually stripped both of flowers and branches, and the trees will probably be extirpated before many years by this sort of vandalism.
THE LOCUST.
The waysides in the Middle States do not contain a more beautiful tree than the Locust, with its profusion of pinnate leaves and racemes of flowers that fill the air with the most agreeable odors. In New England the Locust is subject to the ravages of so many different insects that it is commonly stinted in its growth, its branches withered and broken, and its symmetry destroyed. But the deformities produced by the decay of some of its important limbs cannot efface the charm of its fine pensile foliage. In winter it seems devoid of all those proportions we admire in other trees. It rears its tall form, withered, shapeless, and deprived of many valuable parts, without proportional breadth, and wanting in any definite character of outline. Through all the early weeks of spring we might still suppose it would never recover its beauty. But May hangs on those withered boughs a green drapery that hides all their deformity; she infuses into their foliage a perfection of verdure that no other tree can rival, and a beauty in the forms of its leaves that renders it one of the chief ornaments of the groves and waysides. June weaves into this green leafage pendent clusters of flowers of mingled brown and white, filling the air with fragrance, and enticing the bee with odors as sweet as from groves of citron and myrtle.
The finely cut and delicate foliage of the Locust and its jewelled white flowers, hanging gracefully among its dark green leaves, yield it a peculiar style of beauty, and remind us of some of the finer vegetation of the tropics. The leaflets, varying in number from nine to twenty-five on a common stem, have a singular habit of folding over each other in wet and dull weather and in the night, thus displaying a sensitiveness that is remarkable in all the acacia family. The Locust is not highly prized by landscape gardeners, who cannot reconcile its defects to their serpentine walks and their velvety lawns. But I am not sure that the accidental deformities of the Locust may not contribute to its picturesque attractions, when, for example, from its furrowed and knotted trunk a few imperfect limbs project, and suspend over our heads a little canopy of the finest verdure.
Phillips says of the Locust, that, when planted in shrubberies, it becomes the favorite resort of the nightingale, to avail itself of the protection afforded by its thorns. There are many other small birds that seek the protection of thorny bushes for their nests. On the borders of woods, a barberry or hawthorn bush is more frequently selected by the catbird and the yellow-throat than any other shrub. I have observed that the indigo-bird shows a remarkable attachment to the Locust, attracted, perhaps, by some favorite insect that lives upon it. The only nests of this bird I have ever discovered were in the branches of the Locust. It is worthy of notice, that, notwithstanding its rapid and thrifty growth in favorable situations, this tree never occupies exclusively any large tracts of country. It is found only in small groups, scattered chiefly on the outside of woods containing different species. The foliage of the Locust, like that of other leguminous plants, is very fertilizing to the soil, causing the grassy turf that is shaded by this tree to be always green and luxuriant.
THE HONEY LOCUST.
The Honey Locust is not an uncommon tree in the enclosures of suburban dwellings, and by the waysides in many parts of the country. Some of them have attained a great height, overtopping all our shade-trees except the elm and the oak. This tree in June bears flowers without any beauty, hanging from the branches in small greenish aments. The outer bark peels from the trunk, like that of the shellbark hickory. The thorns investing the trunk as well as the boughs are very singular, consisting of one long spine with two and sometimes more shorter ones projecting out of it, like two little branches, near its base. Three is the prevailing number of these compound thorns. Hence the name of Three-Thorned Acacia applied to the Honey Locust.
This tree bears some resemblance to the common Locust; but its leaflets are smaller, and of a lighter green. It is not liable, however, to the attacks of insects, and is seen, therefore, in all its normal and beautiful proportions. It displays much of the elegance of the tropical acacias in the minute division and symmetry of its compound leaves. These are of a light and brilliant green, and lie flat upon the branches, giving them a fan-like appearance, such as we observe in the hemlock. Though its principal branches are given out at an acute angle, many of them are horizontal, extending outwards with frequent contortions. The Honey Locust derives its name from the sweetness of the pulp that envelops the seeds contained in their large flat pods. This tree is not an uncommon hedge plant in Massachusetts, but it is not found in the New England forest. Its native region is the wide valley between the Alleghanies and the Mississippi River.
RELATIONS OF TREES TO THE ATMOSPHERE.
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.
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.