A year among the trees

by Wilson Flagg

Trees, especially in dense assemblages, may therefore, in frequent instances, be the immediate occasion of showers, by conducting to the earth the electric fluid of the clouds, and inducing that non-electric state which precedes the discharge of rain. This seems to be effected by electric disorganization. An organized cloud is an aggregation of vaporous particles, which are suspended in the atmosphere and held in a state of union without contact. Being in a similarly electrified condition, they are kept separate by that law of electricity which causes two pith-balls, suspended by threads, when similarly electrified, to repel each other at certain distances. All those clouds that show a definite and organized arrangement, and resemble feathers or lace, are charged with electricity. As they accumulate they lose their symmetrical arrangement, but do not mix, until some object, charged with opposite electricity, comes near them and draws from the mass its electric fluid, when the vaporous particles, losing their mutual repulsion, immediately coalesce and descend in rain.

To illustrate the action of trees in producing showers, we will suppose a dense electric cloud to be passing over a dry plain containing only a few trees. Not meeting with any conducting objects of appreciable force on its journey, it remains suspended in the heavens until it reaches either a large collection of water, or encounters a forest, over which, as over a lake, there rests always, in calm weather, a stratum of invisible moisture, which is a powerful conducting agent. The trees, with their numerous vegetable points, and the vapor that overspreads them, combine their force in drawing down the electric fluid from the cloud passing over, causing the whole mass to descend in showers. The damp stratum of air which, in still weather, rests upon the surface of every large sheet of water, being a powerful conductor, serves to explain a phenomenon often observed in a dry season near the coast. A dense electric cloud is seen to pass over our heads, without shedding a drop of rain, until it reaches the ocean, when the humid air above the waves, acting as a conductor, causes the cloud to part with its electric fluid and to fall in copious showers at the same moment.

Occasionally a similar cloud, after rising in the west about thirty degrees, will be turned from its direct course, and repelled by the dry, heated atmosphere resting on the plain, and, attracted by the invisible cloud of moisture that hovers over the river valley, is seen to take the course of the river in its journey toward the sea. Hence it is notorious that in a very dry time the rivers obtain more showers than the plains, and the wooded mountainous regions more than the open and level country. And we may regard it as a happy accident in the economy of nature, that trees should be the most serviceable in nearly all other respects, hardly less than as electric agents, upon those situations which are of the least value for the purposes of agriculture. Their branches on lofty ridges and elevations, extending near the level of the lower clouds, are like so many lightning-rods on the buildings of an elevated city, and exert a powerful influence in conducting the electric fluid from an overcharged atmospheric stratum, and preventing, in some degree, those accumulations that produce thunder-storms. Nature employs this grand vegetable apparatus as one of the means of preserving that equilibrium, both of moisture and electricity, which cannot be greatly disturbed without dangerous commotions.

I have said nothing of trees as a protection from lightning; but there are many curious facts and superstitions on record in relation to this point. “When a thunder-storm threatened,” as Suetonius relates, “Tiberius never failed to wear a crown of laurel-leaves, impressed with the belief that lightning never touched the leaves of this tree.” The general opinion that certain trees are exempt from the stroke of lightning is very ancient. It probably originated in some religious ideas of their sanctity, and men in more enlightened times have endeavored to explain it by philosophy, instead of rejecting it as fable. It was affirmed by Hugh Maxwell, an American writer, that lightning often strikes the elm, the chestnut, the oak, the pine, and less frequently the ash; but it always evades the beech, the birch, and the maple. Captain Dibdin remarks, in a letter to Alexander Wilson, that in the forests of Virginia the pines, though taller than the oaks, were less frequently injured by lightning, and considers them pretty secure when growing among oaks. These accounts by different writers are too various and contradictory to be of much value in aiding us to discover the truth. It is probable that the partial exemption of certain trees from the stroke of lightning, if any such accounts be true, depends on their size and shape. A tall tree in an assemblage would be more exposed than the others. It may also be supposed that if a tree has a regular ramification, smooth and straight branches and trunk, it is better formed for a conductor, and that it would be more liable to receive a charge of the fluid. But all these opinions are probably of the same character with those respecting the antipathy of serpents for certain trees,—traditionary notions which are hardly worthy of investigation. The opinion of the ancients concerning the immunity of the laurel was probably derived from their idea of its sanctity as the tree which was dedicated to Apollo. At the present day there exists in Italy a similar notion concerning the white grapevine. Some of the peasantry of that country are accustomed to twining its branches around the head and waist as a protection from a thunder-stroke.

Trees are generally believed to protect a house adjoining them from lightning; on the contrary, it is known that men and animals seeking refuge under a tree in an open plain are in greater danger than outside of it. The lightning is therefore probably conducted by the water passing down on the surface of the branches and trunk; for if the tree itself were the conductor, the lightning would pass through the trunk into the ground, and, like a lightning-rod, act as a protection to objects near, but not in contact with it. Dr. Franklin thought the safest place a few yards distant from a tree, and a little outside of its widest spread. It is unsafe to stand under the drip of a tree, which might convey to the person an electric charge. It was the opinion of M. Arago, that trees overtopping houses at small distances cannot be regarded as affording sure protection, like a properly adjusted lightning-rod; but he admitted that when a storm passes over a forest it is decidedly enfeebled. The forest certainly diminishes the power of a thunderbolt. The security derived from trees attaches principally to large assemblages. Though a house may receive but little protection from a few tall trees standing near it, it is not to be denied that a village or hamlet is rendered more secure by adjoining woods.

THE GROUND LAUREL.

There is only one Epigea in this country,—a very fragrant and beautiful species, creeping close to the ground, and bearing dense clusters of pearly flowers, edged with crimson. The flowers are not unlike those of some of the heaths, though of larger size. It grows abundantly in many parts of New England, particularly around Plymouth, and in various localities from Canada to Georgia. It is a creeping shrub, occupying dry knolls in swampy land, and growing along on the edges of the swamp upon the upland soil. The leaves are almost round, evergreen, light-colored and slightly russet, partially overlapping the dense clusters of flowers, that possess a great deal of beauty and emit an odor like that of hyacinths.

No plant has more celebrity among our people than the Ground Laurel, the earliest of all our wild flowers. I cannot consent to apply to it the common unmeaning name of “Mayflower,” thus associating it with the fetid Mayweed, and falsifying its character by an anachronism that assigns to the month of May a flower belonging to April. The name of Mayflower, as applied to the Epigea, means nothing except what is false. Almost all our early flowers belong especially to the month of May. This is distinguished from them by appearing almost alone in April. Its popular appellation is a plain misnomer; and as an apology for it, the name is said to have been given to it by the Pilgrims, in commemoration of the ship that brought them to this country. I cannot believe the Pilgrims ever took any notice of it. Mayflower is a name that originated with some ignorant people, who could not think of any better name than the one it bears in common with fifty other species.

THE BEARBERRY.

The Bearberry is a more common plant, and more elegant in its foliage, with less conspicuous flowers, than the ground laurel. This plant covers extensive tracts on the borders of woods and partially under their protection. The foliage, resembling that of the box, has always been admired, and nothing makes a neater or more beautiful covering of the turfs which it adorns. The Bearberry is a native of both continents. It abounds in light sandy soils, forming a frequent undergrowth of a pitch-pine wood. The berries are eaten by quails and robins in winter, when they can seldom find any animal food except a few dormant insects.