Cork oak

“ It has abundance of dark-green ovate leaves, mostly prickly at the margin; the acorns are oblong on short stalks; the stem grows to the height of 80 ft.; the wood is dark-brown and hard, weighing 70 lbs. the cubic foot, while the same of the Quercus ruber or British oak weighs only 55 lbs., and the tree attains a vast age. The cork oak, Quercus suber, grows either singly among other trees or in groups, principally in the southern parts of the island. The bark is of little commercial importance.
Agriculture.
The inhabitants do not assist nature. ”

“ The annual consumption must be enormous; it is wonderful how the supply is maintained. Having no qualities to recommend it to the landscape gardener, the cork oak is only fit for growth in this country as a curiosity, and there only in the eastern and southern English counties. In the midland and northern districts it may exist, but cannot rightly thrive. ”

“ The corky part of the bark which is outside is composed of closed cells, exclusively, so built together that no connection of a tubular nature runs up and down the tree, although horizontal passages radiating toward the woody parts of the tree are [26] numerous. In the woody part of the tree, on the contrary, and in the inner bark, vertical passages or tubes exist, while a connection is kept up with the pith of the tree by means of medullary rays. In one species of tree, known as the cork-oak, this is strongly developed. ”

“ It is used also by fishermen as floats for their nets.
These various applications were known to the Greeks and Romans, as shown by the works of Theophrastus and Pliny. The latter says of the cork-oak: “Nothing is utilized but its bark, which is very thick, and which is renewed in measure as it is removed. This bark is often used for the buoys of anchors and ships and of fishermen’s nets, for the bungs of casks, and for women’s winter foot gear. The Greeks called the cork-oak the ‘bark tree’.... Cork bark is used as a covering for roofs.” ”

“ With these exceptions, however, the major part of the yield is exported to the United States, England, France, Germany, Austria, Russia, Denmark, or Sweden, to be turned into finished form.
Weighing Bark in the Forest
The cork oak, known botanically as Quercus suber, attains a height of from twenty to sixty feet and measures sometimes as much as four feet in diameter. ”

“ The whole region of Les Maures is dominated by the chêne-liège, or the cork-oak. Usually they are great, straight-trunked trees with a heavy foliage. Some still possess their natural brown trunks, and some are a gray fawn colour, showing that they are already aged and have been many times robbed of their bark for the manufacture of floats for the fisherman’s nets and corks for bottles. The first coat which is stripped has no mercantile value, and the trunk is left to heal itself as best it may, the sap oozing out and forming another skin, which in due time forms the cork-bark of commerce. ”

“ Palm-wood is light easily worked and soft like cork-oak, but is superior to that wood, as it is tough, while the other is brittle. Wherefore men now make their images of palm-wood and have given up the wood of cork-oak. However the fibres do not run throughout the wood, nor do they run to a good length, nor are they all set symmetrically, but run in every direction. ”

“ Sometimes the corky layer grows and forms new layers, inside of the old, for years, as in the Cork-Oak, the Sweet Gum-tree, and the White and the Paper Birch. But it all dies after a while; and the continual enlargement of the wood within finally stretches it more than it can bear, and sooner or later cracks and rends it, while the weather acts powerfully upon its surface; so the older bark perishes and falls away piecemeal year by year. ”

“ It remained for the elder Pliny, however, in his wonderful work on natural history, written in the first century of the Christian era, to make the most remarkable reference to cork to be found in ancient literature: “The cork oak is but a very small tree and its acorns of the very [Pg 7] worst quality * * *; the bark is its only useful product, being remarkably thick, and if removed will grow again * * *. ”

“ Among the definitive physical factors by which the composition of a forest is determined—the rainfall, the temperature, the soil, and the altitude—probably of the first rank should be considered the rainfall and the temperature, which are affected by the altitude. In the case of the distribution of the cork oak, however, the character of the soil plays an important rôle. This species grows only on sandy soil, and where the rainfall exceeds 600 mm. ”

“ In the French departments of the Landes and Gironde the Quercus Occidentalis forms extensive woods, as also in Spain, Algeria and in some parts of Italy, while the Quercus Suber is a native of the Atlantic side of France and Portugal, where this [13] tree grows to the greatest perfection, and to which countries we are indebted for the major part of our supply. The cork tree bears a general resemblance to the broad-leaved kind of (Quercus Ilex, Holm) or evergreen oak, of which species some authors consider it only a variety; but when full grown it forms a much handsomer tree. ”

“ Again some have thin bark, such as bay and lime; others have a thick bark, such as the oak. And again some have smooth bark, as apple and fig; others rough bark, as 'wild oak' (Valonia oak) cork-oak and date-palm. ”

“ He tells us the cork-tree did not grow throughout Italy, and in no part whatever of Gaul. At the present day it is abundant in France, and Fee states that the acorns of Quercus suber are of an agreeable flavor, and the hams of Bayonne are said to owe their high reputation from the pigs having fed on the acorns of the cork-tree. Some ancient authors speak of the cork-tree as the female of the holm-oak (Quercus ilex) , and in countries where the holm does not grow, they used to substitute the wood of the cork tree. ”

“ Because of the unison of response to common environmental factors, much of the forested area, especially at the higher altitudes, is composed [19] of one species or one species largely predominates. This is true of the pine and the cedar forests to a marked degree; e.g., in the pine forests on Mount Gorno and the cedar near Batna.
Commercially speaking, the cork oak is at present the most important species in Algeria. It occupies about 600,000 acres, and the yearly yield is valued at nearly $1,000,000. It may be seen along the railroad between Tunis and Constantine and east of Algiers. ”

“ The rock elm or cork elm chooses dry, gravelly upland and low heavy clay soil, on rocky slopes and river cliffs, from Ontario and New Hampshire westward through northern New York, southern Michigan to Nebraska and Missouri. It is more abundant and of largest size in Ontario and in the southern peninsula of Michigan.
Its leaf is small, thick, and firm, dark green, and turns to brilliant yellow in the autumn. Its flowers and fruits are borne in racemes. At any season, one knows this cork elm by the shaggy bark on its stout limbs that make the tree resemble a bur oak. ”

“ After eight or ten years this is also removed, and, while more valuable than the virgin cork, it is not as fine in quality as that of the third and subsequent strippings, which follow at regular intervals of about nine years. At the age of about forty years the oak begins to yield its [Pg 14] best bark, continuing productive as a rule for almost a century, although cork trees several hundred years old are not unknown. ”

“ The trees, by a sort of instinct, shall we say, withdraw their cohorts of green-liveried workers from the front as autumn approaches and deck themselves in the more gaudy but less wholesome colors of declining life. It is after the chlorophyll is withdrawn that the layer of cork is formed. The sturdy oak usually holds his brown leaves until they are whipped off by the wind.
The plants have been using light as a motive power for ages, while man, with his much-vaunted reason, is just beginning to utilize the kindred force, electricity, in arts and sciences. ”

“ A cork is sometimes useful for forming knots on the dark part of the color, and it should be twisted with the finger and thumb to give the light and shade. The heart and sap of the wood should be taken out with a fitch, in the same way as for light oak, but there is not much of the ordinary figure in pollard oak. A flat graining brush, well filled with thin black, will produce the top grain in a curly form, and finally the work should be glazed with Vandyke brown, with a touch either of black or of burnt sienna. ”

“ The development of the layers of cork which now surround the thickening axis-cylinder go on forming year after year, as the cambium forms more xylem and phloëm and so thickens the root; were this not the case, the layer of cork would soon be ruptured as the root increases in diameter. Such rupture, in fact, does occur, but the cork-forming tissue in the pericycle goes on growing and acts as a cork-cambium, and repeatedly develops more cork to make good the layers which are being split and worn off in the soil. ”

“ The stems of the cork elm and the mossy cup oak have these peculiar corky layers, but neither of them have smooth, polished stems between the broken ridges, nor such radiant color as those of the liquidamber. When this tree [Pg 145] grows in open situations its trunk divides a short distance from the ground, and the branches form a pyramidal head. In moist Southern forests, however, where the liquidamber grows to be very tall, its trunk is straight, a uniform size in diameter, and often undivided into branches to the height of seventy or eighty feet. ”

“ There are nearly fifty species of Oaks which may be obtained in the British nurseries; the most remarkable of which are the Cork tree (Quercus Suber) , the cork being the bark; the Evergreen Oak (Q. Ilex) ; the American Oaks, particularly the scarlet Oaks (Q. coccinea and Q. rubra) , the Live Oak (Q. virens) , and the Willow Oak, with long narrow entire leaves
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(Q. Phellos) ; and the Turkey, Fulham, and Lucombe Oaks (Q. Cerris and its varieties) . All Oak trees are very liable to be attacked by a species of gnat, and which produces excrescences on the branches. ”

“ On the side of the mountains facing the north are forests of 131 chestnut trees, some very old and of most fantastic forms, while on the opposite side are forests of sombre cork oaks. Cork-cutting, wine-making, and the exportation of chestnuts form the principal industries. ”

“ The cork tree gives but little shade, which contributes greatly in causing the soil to become dry. To avoid all these inconveniences, which are highly unfavorable to the good production of cork, it is requisite that young plants grow up with sufficient foliage, so that the branches touch each other, and even overreach, till they are about twenty-five years old. ”

“ Just what the cork does for the bottle, the sheets of cork wrapping round the branches do for the plant. They prevent it from being dried up by cold winds, and they keep out the heavy rains of winter which would injure it. Roots have a cork coating also when they get old. As you may remember, it is only the tip of the root which can absorb water for the plant, so that in the young part of the root a cork layer would be very much out of place, and you will never find it there. ”

“ The inner cannot be removed without destroying the life of the tree.
Virgin cork is not of much value; it is employed only for nets, and has no elasticity.
Only after the third harvest is the cork in perfect condition. The tree is then about forty years old. It is first skinned (démasclée) when the tree is aged twenty or five-and-twenty. The second peeling takes place when it is aged thirty or five-and-thirty. The third and best is collected when the tree is between forty and forty-five years old. ”

“ The cortex or outer bark serves to protect the stem of the tree from extremes of heat and cold, from atmospheric changes, and from the browsing of animals. It is made up of a tough water-proof layer of cork which has taken the place of the tender skin or "epidermis" of the twig. Because it is water-proof the outside tissue is cut off from the water supply of the tree, and so dries up and peels off, a mass of dead matter. The cork and the dead stuff together are called the bark. ”

“ American zone was all that could be desired for the favorable rearing of cork trees; but strange to say this was not the case. Although the growth of the tree had been exceptionally strong, the quality of its salient product turned out to be of an inferior character. The cork generally improves with the age of the tree; in this instance, however, even after years of maturity the cork harvest did not improve to any great extent, and indeed is still of a second-rate quality. ”

“ As years go on, and this layer in its turn splits and peels, others are formed further inward, and if it is remembered that a layer of cork is particularly impervious to water and air, it is easy to understand that each successive sheet of cork cuts off all the tissues on its exterior from participation in the life processes of the plant: consequently we have a gradually increasing bark proper, formed of the accumulated cork layers and other dead tissues. ”

“ If the soil is poor, the cork is thin but of fine quality and very appropriate to make the best stoppers. If, on the contrary, it is rich, the cork is thick but spongy. Consequently it is requisite to treat the cork tree in such a manner that whilst the cork grows thick it will at the same time be fine in texture. ”