Part 25

That beautiful book upon the table is bound in Russia leather. The acorn cups of a European oak were used to tan the skins that made this leather so much more beautiful than that of your shoes. Your gloves are made of kid skins tanned in Europe. For this particular work the nut-like galls that grow on certain oak trees are gathered in the woods.

Tannin is the substance in oak bark which makes it valuable in tanning leather. A high percentage of tannin is found in oak galls. For this reason they are gathered in many countries, and are among the most valuable and high-priced supplies for the establishments that tan skins for gloves. The most expensive inks and dyes, those that do not fade, but are practically permanent, are made from selected oak galls.

Oak apples are a strange fruit, found in more or less abundance on the leaves of our own oak trees in autumn. You have seen them in summer time, plump, green balls, sometimes as large as a hen’s egg, but globular, sitting upon a leaf. In autumn the balls take on the colour of the dying leaves.

The same tree may have hard little marble-like balls growing on its twigs. These are of different sizes, and it is not unusual to find a hole in the side of each.

All such outgrowths on the leaves and twigs of oaks are called galls, and they are chiefly caused by winged insects called gall-gnats. An egg is laid in early spring, in a slit pierced in the twig or leaf. As this egg hatches, the tissue about it is disturbed in its growth by the presence of this feeding grub. The soft leaf pulp, or the tender tissues of the twig that surround it, are exactly what the grub likes to eat. Food and drink are all about it, and as it feeds, it grows. The leaf swells, and so surrounds the grub with an abnormal growth. The grub still feeds, and the swelling becomes larger, until finally, when the insect ceases to eat, it is housed in the peculiar ball which we know as an oak gall. Each species of gall-maker is known by its house.

The oak apples are of several kinds. Some are empty except for a little shell in the centre, in which the fat grub sleeps. Sometimes the substance within the “apple” is corky, sometimes spongy. Bullet galls, which form on twigs like little marbles, are usually solid to the centre, where the grub lies until the time comes for it to bore its way out to the surface, and fly away, to lay eggs which will produce other galls. Usually oak galls, found in winter, contain the sleeping grub, whose transformation into a winged insect waits until the coming of spring.

The cork in your ink bottle is the bark of an oak tree. Go to Portugal or to Northern Africa, and you may see the cork harvest in progress in July or August. There is no place to go for genuine cork except to a small evergreen oak that rarely reaches a height over thirty feet. When these trees are twenty-five years old, a hard, thin layer of bark is stripped off. This is a valuable tan bark, but it is not in the least corky. The tree now produces a spongy bark entirely different from the first. It is not disturbed for eight or ten years. This is stripped off. It is the poor quality of bark which fishermen use to float their nets with.

Ten years later the bark is stripped again. It is better in quality than the first. Each ten years brings the bark stripper again to the tree. In the fiftieth year, the bark is of the finest quality, and for fifty years that follow there are five strippings of bark of the highest grade. Then the quality becomes poorer. The trees are cut down, the bark is sold to the tanners, and the wood is used for charcoal or for fuel.

It is a very particular job to get the cork off and leave the under layer uninjured. The trunk is stripped from the ground to the point where it branches, and the inner “mother bark” must not be bruised, for no more cork will grow on any bruised spot. Two circular cuts are made, one at the top, one at the bottom of the columnar trunk, then two opposite slits are made dividing the bark of the trunk into two halves. These curved plates are worked off by inserting a wedged-shaped tool between the bark and the trunk, and gradually working it further in until the whole curved plate of cork comes off. These two big sheets are steamed and flattened, then bound in bundles, and shipped to wholesale dealers in cork.

The owner of a grove of cork oaks must wait ten years between crops of the bark, but every year three crops of acorns are borne on these trees. The pigs of the owner, turned into the grove, fatten on this rich food. So the little trees are very profitable in two ways.

In the south of Europe, the handsome, evergreen holm oak grows wild; its glossy leaves and compact form remind us of our holly trees. It is one of the most valuable ornamental oaks, but as a fruit tree, it has unusual value. Its acorns are sweet and rich, and the crop is heavy. Hogs are fattened upon them. In earlier days they were used as human food, and even now gipsies gather them to eat. Its acorn cups, bark, and the galls it bears are of the very best quality. They are used in the most particular jobs of dyeing and tanning.

Under ground, the holm oak bears a strange fruit—a fungus called “truffle” develops on the roots. These truffles are somewhat like mushrooms in their growth. They are far more delicious to eat, and expensive to buy than ordinary mushrooms. The best of them are found in France, and French people are especially fond of them.

Trees that grow on chalky lands are more likely to produce truffles. At a dozen years old, they begin to yield, and truffles may be found upon their roots for about twenty-five years.

Not every holm oak has truffles on its roots. The finding of these delicacies is a very interesting and exciting game, and a great deal of a lottery. There is but one way to find them, and that is by the sense of smell. The truffle has a rich, strong odour. Dogs and pigs are the only animals that are able to find it. The truffle-hunter is usually an old woman, who goes with a trained pig or a trained dog into the oak forest. She has a basket, and a spading fork, and she keeps a close eye on her four-footed partner. If the pig, in rooting about under an oak, suddenly becomes excited, and begins to root furiously, she drives him away, and digs out the precious ball of fungus he has scented. It is irregular in form, and looks somewhat like a potato. Meanwhile the pig locates another, and is again disappointed. The truffle dog is treated in the same manner. Unless put into a pen, or chained at night, these truffle-hunters are likely to take to the woods and feast when no one is by to interfere with their pleasure.

Truffles are shipped in cans to the United States, but we have not yet discovered them growing on the roots of our oak trees. Probably we have not yet looked for them with sufficient care and patience.

APPENDIX

APPENDIX IDENTIFICATION KEYS TO TREE GROUPS AND FAMILIES

A KEY TO NEEDLE-LEAVED EVERGREENS

A. Leaves few, in sheathed bundles, set spirally on the twig. THE PINES. AA. Leaves solitary, set spirally on the twig. B. Twigs with bracket-like projections for attachment of leaves; cones hanging down. C. Leaves flat, blunt, with short stalks. The Hemlocks. CC. Leaves angled, sharp, without stalks. The Spruces. BB. Twigs smooth; cones standing erect. The Firs.

A KEY TO THE PINES

A. Sheaths of leaf-bundles soon shed; wood soft, pale. SOFT PINES. B. Needles, 5 in a bundle. C. Cones, 5 to 8 inches long; Eastern. White Pine. CC. Cones, 12 to 18 inches long; Western. Sugar Pine. BB. Needles fewer than 5 in a bundle; Western. Nut Pines. AA. Sheaths of leaf-bundles not soon shed; wood hard, heavy, dark, resinous. HARD PINES. B. Needles, 3 in a bundle. C. Length of needles, 8 to 18 inches; cones, 6 to 10 inches. Longleaf Pine. CC. Length of needles, 6 to 9 inches; cones, 3 to 5 inches. Loblolly Pine. CCC. Length of needles, 3 to 5 inches; cones, 1 to 3 inches. Pitch Pine. BB. Needles, 2 in a bundle; Northern. C. Length of needles, 4 to 6 inches; cones 2 inches. Red Pine. CC. Length of needles, 1 to 3 inches; cones, 2 to 3 inches. Jersey Pine. BBB. Needles, 2 or 3 in a bundle; Southern. C. Length of needles, 3 to 5 inches; cones, 1 to 3 inches. Shortleaf Pine. CC. Length of needles, 8 to 12 inches; cones, 3 to 6 inches. Cuban Pine.

A KEY TO THE SCALE-LEAVED EVERGREENS

A. Seeds borne in a woody cone; twigs flattened, leaves minute. Arbor Vitae. White Cedar. AA. Seeds borne in a fleshy, blue berry; leaves scale-like or spiny, or both. Juniper. Red Cedar.

A KEY TO THE NUT TREES

A. Nuts in a husk that opens when ripe. B. Husk opens in four divisions. C. Surface of husk, spiny. D. Nut three-angled, small, two in a husk. Beech. DD. Nut rounded, or flattened, 2 or 3 in a husk. Chestnut. CC. Surface of husk not spiny. Hickories. BB. Husk opens in three divisions. Horse-chestnuts and Buckeyes. BBB. Husk opens in two divisions; spiny. Chinquapin. A. Nuts in a husk that does not open when ripe. B. Shape of nut, globular; surface, smooth. Black Walnut. BB. Shape of nut, oblong; surface, clammy. Butternut.

A KEY TO THE GROUPS OF OAKS

A. Acorns, annual; bark usually pale; leaves with rounded lobes, not spiny-pointed. The White Oak Group. AA. Acorns, biennial; bark usually dark; leaves with spiny-pointed lobes. The Black Oak Group.

A KEY TO THE WHITE OAK GROUP