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.