The acorn cups of Quercus Valonia are exceptionally rich in tannin, and are sifted out from the nuts and sold under the trade name, Valonia, to the best tanneries in Europe.
Oak bark is a staple tan bark the world over. The black and chestnut oaks in this country and the English oak in Europe are richest in tannin. Spent bark from the pits holds heat. It was formerly used in private greenhouses under the soil to force exotic fruits, especially pineapples, in England. It is now spread on race tracks, roadways, paths and sidewalks.
Insect Enemies.—Numerous insects and fungi prey upon oaks. Great caterpillars of our most beautiful night-flying moths devour the young foliage. Weevils infest the acorns, gall insects distort the leaves and twigs, scale insects suck the juices from the young branches. Certain of these enemies of the oaks have been turned to good account by man. The scale, Kermes, is a soft bodied creature, diminutive in size, but infinite in numbers. Its eggs are gathered and dried, much as the cochineal insects are, and a valuable scarlet dye is made of them. This industry belongs to the countries of southern Europe and northern Africa, where the Kermes is used for dyeing leather and wool. In France cosmetics are tinted with it.
Oak apples" are abnormal growths on the leaves or twigs of oaks due to the presence of the larvx of certain insects whose eating seems to poison the tissues and distort their development. An entomologist knows by the form of the gall what insect produces it. In ancient times people knew little of their causes—the "apples of Sodom" and "Dead Sea fruit" of history, sacred and profane, were galls of oaks. The "flea seed" of California oaks contain the young of a species of the genus Cynips. A glance into almost any oak tree just as the buds are opening will show delicate, wasp-like insects resting lightly for a moment on one leaf cluster after another, depositing eggs, one in a place, within the leaf substance. The beginnings of oak apples may be found as large as peas on leaves scarcely an inch long. John Gerard, the herbalist, writing in 1597, naïvely expresses the misconceptions and superstitious beliefs of his day in England.
"The gall tree," he explains at the outset, "is a kinde of oke." Then proceeding: "The oke apples being broken in sunder about the time of their withering doe foreshew the sequell of the yeare, as the expert Kentish husbandmen have observed, by the living things found in them: as, if they finde an ant, they foretell plenty of graine to ensue; if a white worm like a gentill or then they prognosticate murren of beasts and cattell; if a spider, then (say they) we shall have a pestilence or some such like sickness to follow amongst men; these things the learned also have observed, and noted that before they have an hole through them they contain in them either a flie, a spider, or a worme; if a flie, then warre ensueth; if a creeping worme, then scarcities of victuals; if a running spider, then followeth great sicknesse or mortalitie."
Oak galls are rich in tannin, sometimes yielding as high as 77 per cent. They have always been used in various countries in tanning the finest skins, and in making inks and dyes. The Aleppo galls from northern Italy rank highest. The oldest docu ments in America show the ink still bright on the yellowing parch ment, for it was made of oak galls and is practically permanent.
Dyes are equally lasting, in distinct contrast to the cheap aniline dyes in use nowadays, and the inks that fade in a year or two. Here is something startling. A writer in England three centuries ago thus recommends these galls to horse jockeys: "A handful or two of small Oak buttons, mingled with Oats given to Horses, which are black of colour, will in a few days eating alter it to a fine Dapple grey." truffles of commerce, famous in the French cuisine and well known to the gourmands in Rome's palmiest days, are edible fungi, somewhat like puff balls in texture and mode of growth. They grow as parasites upon the roots of various trees, including the Holm oak and the English oak. Limy soil is required by these fungi. They are produced in southern England and on the Continent, reaching their highest perfection in France and Italy. "The reputation of the truffle of Perigord is as old as the world!" In an impassioned ode to this delicacy, a famous Frenchman uttered this apostrophe: "Noir diamant, perle de la Gascogne, Tous les gourmets venerent ton pays!" Truffles bring astonishing prices in the markets of Europe. This fact alone quite justifies the planting of chalky lands to oaks. Yield of truffles is expected when the trees are a dozen years old, and it continues without abatement for twenty-five years if con ditions remain favourable.