Part 3

The Mediterranean Basin is particularly suitable for the rearing of corkwood, and although many attempts have been made to transplant the seed, the results have proven fatal.

Notable among these attempts being the American ambition to introduce the tree in the United States. Portuguese acorns were brought to Wayne County, Mississippi, and planted in 1859; the result, as far as the growth was concerned, was splendid; but after a wait of eleven years, the final crop was not a commercial success. Another attempt was made in 1872, in southern California, but with no better outcome than the first, in which some of the trees attained to a height of thirteen feet (3.965 meters) and the stem, to a diameter of eleven inches (2.794 decimeters), including the cork, which attained a thickness of one inch (2.540 centimeters). This evidently rapid growth would infer that the 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. And Consul S. C. Reat, writing from Tamsui, recently reports the efforts of the Japanese Government to plant cork trees in Formosa and the Ogasawara Isles, in the endeavor to supply small corks to the Japanese merchants, the result of which, is yet to be learned.

Chambers Journal.

THE TREE AND GROWTH

Many botanists consider the cork oak of Europe as belonging to two species, one chiefly characterized by annual fructification and the persistence of the leaves for two or three years (Quercus Suber, Linnæus); the other by biennial fructification and annual persistence of the leaves (Quercus Occidentalis, Gay).

Garden and Forest, Vol. VIII, 52.

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 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.

“In the localities to the north the cork is better than those exposed to the south. It grows and develops in ground of very little depth, and sometimes in ground, in appearance very stony. It is seldom found in calcareous soil, preferring always a soil of feldspar, and like the chestnut flourishes best in a sandy one.”

Consul Schenck’s Report.

The cork-oak attains a height of from six to eighteen meters, at times reaching fifty meters and measures as much as 1.22 meters in diameter. Its branches are covered with small evergreen leaves, which are rather spongy and velvety to the touch, have a glossy appearance and a saw-tooth edge, measuring about three to five centimeters long and one and one-half to two wide. The roots are strong and spread considerably, and frequently are to be seen on the surface of the ground. The flowers or blossoms make their appearance in May; the fruit ripens in the fall or winter, from September to January, and falling from the tree as soon as ripe. Three qualities of acorns are to be observed according to their time of ripening and are called, “brevas primerizas de San Miguel,” which ripen in September; the second or middling “Martinencas,” which ripen in October and November; and finally the “tardias Ó palo-Meras,” which ripen in December and January. These acorns form one of the forest’s chief sources of revenue, since fed to swine, they give a peculiarly piquant flavor to the meat, Spanish mountain hams being noted for their excellence.

Meter = 3.28 feet.

In a cork-wood of Montenegro (municipal district of Quart, Province of Gerona) the property of D. Romulo Bosch, and near the place called La Mina, we measured in August, 1877, a tree that was 4.95 meters in circumference, breast high, and the trunk of the tree five meters high, calculating its age between one hundred and fifty and two hundred years old. Consul Schenck’s Report, 1890.

Centimeter = .3937 inch.

Consul Schenck’s Report, 1890. Authority M. Fee.

In the following paragraphs I will quote principally from Consul Schenck’s Report, 1890, relating to the growing and procuring of the bark for shipment, with interpolated sentences and slight changes, made necessary by other data at hand. The most common practice is to cultivate this plant by sowing, which is frequently done, above all, in ground somewhat manured, making alternate furrows with vines. Up to their twentieth or twenty-fifth year the ground is cultivated as if it were a vineyard, rooting up at that age the vines on account of producing less fruit, and also on account of the cork trees being pretty well grown up and no longer requiring the shelter of the vines. At the end of even one year it is difficult to transplant the cork tree on account of the length of the roots, principally the central one, and if the trees are put out with the intention of transplanting they are generally sewn in a false ground bottom made artificially at a certain depth with layers of stones or bricks. French silviculturists recommend about 110 to 120 trees to the hectare (2.471 acres).

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. It may be convenient, if there is not sufficient foliage from the cork trees themselves, to introduce secondary species, such as the elm tree, ash and pine, known as (pi meli), these being depended upon to supply the requisite coolness and manure to the ground. 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. This is of course an agricultural problem and may differ from year to year in the necessary details.

DISEASES

The cork tree has in no wise escaped from disease and infections; on the contrary it has its full allotted share which worries the growers more than the acquiring of a perfect texture, and unless great care is taken will greatly reduce the value of a crop. The larva of the Coroebus undatus (corch) attacks the interior of the cork, penetrating frequently into the tree itself, which causes an undervaluation in the quality of the cork, and, moreover, these perforations unite so closely and in such a manner even in the trunk of the tree that in peeling off the cork, part of the skin of the trunk itself comes off, causing much damage to the tree.

The larva of the Cerambyx cerdo, as well as the ant, Formica rufa L. hormigas, destroys the fine cork with their numerous borings and galleries. Jaspered (Jasperado) is the name by which is known one of the defects of the cork which reduces it greatly in value and as far as can be learned comes from the tree itself. The porosity of cork is greatly increased by the presence of cork-meal, resulting from the disintegration of the Sclerenchyma, or stone cells, which penetrate the cork fiber and falling to a powder facilitate the entrance of infection.

Scientific American, 1906.

STRIPPING

The corkwood or cork of commerce is the external part or “periderm” of the cork-oak; and when it has attained a diameter of approximately 12.7 centimeters or the tree measures forty centimeters in circumference according to the Spanish governmental regulations, which the tree does usually by the time it is twenty years old, the bark may be removed. The stripping generally takes place during July and August, and it is a process which demands skill and care, if injury to the bark is to be avoided. In Algeria the French strippers sometimes use crescent-shaped saws, but under the usual Spanish method a hatchet, with a long handle, is the only implement employed. The bark is cut clear through, around the base of the tree, and a similar incision is made around the trunk, just below the spring of the main branches; the two incisions are then connected by one or two longitudinal cuts, following, so far as possible, the deepest of the natural cracks in the bark. Inserting the wedge-shaped handle, the tree’s covering is then pried off. The larger branches are stripped in the same manner, yielding, generally, a finer grade of cork than that of the trunk. The thickness of the bark ranges from 1.27 centimeters to 6.85 centimeters, while the yield also varies greatly from twenty to 75 kilograms per tree, depending upon its size and age. After the first stripping the tree is left in the juvenescent state to regenerate, and great care must be taken in the stripping not to injure the inner skin or epidermis at any stage of the process, for the life of the tree depends upon its proper preservation, for if injured at any point, growth there ceases and the spot remains forever afterward scarred and uncovered. It is also necessary to avoid stripping during the prevalence of a sirocco, which would dry the inner skin too rapidly and therefore exclude all further formation of cork.

Armstrong Cork Co.’s pamphlet.

Kilogram = 2.205 pounds.

The Capgrand-Mothe system, which, as known, consists of dressing the trunk with the same cork just removed, and leaving it so dressed for a couple of months, has not met with approval, as being impracticable on a large scale. After the stripping, the phellogen, the seat of the growing processes, undertakes at once the formation of a new covering of finer texture, and each year this, the real skin, with its life-giving sap, forms two layers of cells, one within, increasing the diameter of the trunk, the other without, adding thickness to the sheathing of bark. After eight or ten years this sheathing is removed, and while more valuable than the first stripping, 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 best bark, continuing productive as a rule for almost a century. The cork of the first barking is called Corcho-Bornio, Borniza or virgin, and is so coarse, rough, and dense in texture that it is of little commercial value. The second barking is called “pelas,” or secondary cork, and this and subsequent barkings constitute the cork of commerce. As the bark is removed it is gathered up in piles (rusque) and left for a few days to dry. Having been weighed, it is next carried either in wagons or on the backs of burros to the boiling station, where it is stacked and allowed to season for a few weeks. It is then ready for the boiling process. The outside of the bark in its natural state is, as may well be imagined, rough and woody, owing to exposure to the weather. After boiling this useless outer coating is readily scraped off, thereby reducing the weight of the material almost twenty per cent. The boiling process also serves to remove the tannic acid, increases the volume and elasticity of the bark, renders it soft and pliable and flattens it out for convenient packing. After being roughly sorted as to quality and thickness, the bark is then ready for its first long journey, and as the forests are generally located in hilly or even mountainous country, the faithful burro must again be called into service. Truly the Spaniards’ best friend, though the worst treated of all, these patient little animals present a most grotesque appearance when loaded from head to hind quarters with a huge mass of the light bark. Down from the hills they go in trains of thirty, forty or even a hundred, threading the rocky bridle paths in single file and wending their way through the narrow streets of quaint villages where traces of Moorish occupancy may still be seen, to the nearest railway station. The corkwood is there freighted to the various sea-port warehouses in Spain and Portugal, Seville, Spain being perhaps the largest depository and user of raw material. This historic city, situated on the banks of the Guadalquivir, presents a very animated sight in the summer months, and plays a very important part in the cork industry, for besides the numerous warehouses for storing and shipping there are factories for the manipulation of cork and its conversion into the many useful forms in which it has proven of value. Before shipping, the bales are opened, the edges of the bark trimmed and the bark then sorted into the various grades of quality and thickness again. The importance of this last mentioned operation cannot be overemphasized, as the whole problem of the successful and economical manufacture of corks center about it. After sorting it is ready to be rebaled for shipment, this generally being done by placing the large, flat pieces called planks or tables, at the bottom of the bales, and above them the small pieces which are covered in turn with larger sections; then the whole mass being subjected to pressure to render it compact, afterward being bound up securely with steel hoops or wires. Each bale carefully marked indicating the grade or quality, loaded directly into ocean-going steamers and shipped to the ports of the world.

Mr. Lamey, the author of a study upon cork in Algeria, published some interesting tables in this work regarding the annual increase and the mean thickness of cork. According to him cork-bark should not be removed before it has attained a thickness of 2.032 cm., and the formation of new cork has been well explained by Mr. Mathieu in his “Forestry Flora.”

Armstrong Cork Co.’s pamphlet.

From this meager description we at least can learn what “corkwood” is, the limited sphere of its growth, the constant care necessary to insure a successful harvest or gathering, the peculiarities of the tree, its longevity and the general mode of preparing the bark for shipment; the narration in no wise doing justice to this most interesting material, in its natural state, for its growing is a fascinating tale in itself; but for the purpose of this writing the foregoing has been deemed sufficient to convey an understanding of it.