Chestnut (nux Castanea), the common name given to two sorts of trees and their fruit, (1) the so-called “horse-chestnut,” and (2) the sweet or “Spanish” chestnut.
(1) The common horse-chestnut, Aesculus Hippocastanum (Ger. Rosskastanie; Fr. marronnier d’Inde), has been stated to be a native of Tibet, and to have been brought thence to England in 1550; it is now, however, thought to be indigenous in the mountains of northern Greece, where it occurs wild at 3000 to 4000 ft. above sea-level. Matthiolus, who attributes the origin of the name of the tree to the use of the nuts by the inhabitants of Constantinople for the relief of short-windedness and cough in horses, remarks that no ancient writer appears to have made mention of the horse-chestnut. Clusius (Rariorum plantarum hist. i. p. 8, 1601) describes it as a vegetable curiosity, of which in 1588 he had left in Vienna a living specimen, but of which he had not yet seen either the flowers or recent fruit. The dry fruit, he says, had frequently been brought from Constantinople into Europe.
The tree grows rapidly; it flourishes best in a sandy, somewhat moist loam, and attains a height of 50 to 60 or more ft., assuming a pyramidal outline. Its boughs are strong and spreading. The buds, conspicuous for their size, are protected by a coat of a glutinous substance, which is impervious to water; in spring this melts, and the bud-scales are then cast off. The leaves are composed of seven radiating leaflets (long-wedge-shaped); when young they are downy and drooping. From the early date of its leafing year by year, a horse-chestnut in the Tuileries is known as the “Marronnier du 20 mars.” The flowers of the horse-chestnut, which are white dashed with red and yellow, appear in May, and sometimes, but quite exceptionally, again in autumn; they form a handsome erect panicle, but comparatively few of them afford mature fruit. The fruit is ripe in or shortly before the first week in October, when it falls to the ground, and the three-valved thorny capsule divides, disclosing the brown and at first beautifully glossy seeds, the so-called nuts, having a resemblance to sweet chestnuts, and commonly three or else two in number. For propagation of the tree, the seeds may be sown either when fresh, or, if preserved in sand or earth, in spring. Drying by exposure to the air for a month has been found to prevent their germination. Rooks are wont to remove the nuts from the tree just before they fall, and to disperse them in various directions. The tree is rarely planted in mixed plantations where profit is an object; it interferes with its neighbours and occupies too much room. It is generally introduced near mansion-houses for ornament and shade, and the celebrated avenues at Richmond and Bushey Park in England are objects of great beauty at the time of flowering.
The bark of the horse-chestnut contains a greenish oil, resin, a yellow body, a tannin, C26H24O12, existing likewise in the seeds and various parts of the tree, and decomposable into phloroglucin and aesciglyoxalic acid, C7H5O3, also aesculetin hydrate, and the crystalline fluorescent compound aesculin, of the formula C21H24O13 (Rochleder and Schwarz), with which occurs a similar substance fraxin, the paviin of Sir G.G. Stokes (Q.J. Chem. Soc. xi. 17, 1859; xii. 126, 1860), who suggests that its presence may perhaps account for the discrepancies in the analyses of aesculin given by different authors. From the seeds have been obtained starch (about 14%), gum, mucilage, a non-drying oil, phosphoric acid, salts of calcium, saponin, by boiling which with dilute hydrochloric or sulphuric acid aesculic acid is obtained, quercitrin, present also in the fully developed leaves, aescigenin, C12H26O2, and aesculetin, C9H6O4, which is procurable also, but in small quantity only, from the bark. Friedrich Rochleder has described as constituent principles of the cotyledons aphrodaescin, C52H82O23, a bitter glucoside, argyraescin, C27H42O12, aescinic acid, C24H40O12, and queraescitrin, C41H46O25, found also in the leaves. To prepare pure starch from the seeds, Flandin (Compt. rend. xxvii. 391, 1848; xxviii. 138, 1849) recommends kneading them, when peeled and bruised, in an aqueous solution of 1/100 to 1/60 of their weight of sodium carbonate. E. Staffel (Ann. d. Chem. u. Pharm. lxxvi., 1850, p. 379) after drying found, in spring and autumn respectively, 10.9 and 3.38% of ash in the wood, 8.68 and 6.57 in the bark, and 7.68 and 7.52 in the leaves of the horse-chestnut. The ash of the unripe fruit contains 58.77, that of the ripe kernel 61.74, and that of the green shell 75.91% of potash (E. Wolff).
The wood of the horse-chestnut is soft, and serves only for the making of water-pipes, for turner’s work and common carpentry, as a source of charcoal for gunpowder, and as fuel. Newly cut it weighs 60 ℔, and dry 35 ℔ per cub. ft. approximately. The bark has been employed for dyeing yellow and for tanning, and was formerly in popular repute as a febrifuge and tonic. The powder of the dried nuts was at one time prescribed as a sternutatory (to encourage sneezing) in the Edinburgh Pharmacopoeia. It is stated to form with alum-water a size or cement highly offensive to vermin, and with two parts of wheaten flour the material for a strong bookbinder’s paste. Infusion of horse-chestnuts is found to expel worms from soil, and soon to kill them if they are left in it. The nuts furthermore have been applied to the manufacture of an oil for burning, cosmetic preparations and starch, and in Switzerland, France and Ireland, when rasped on ground, to the bleaching of flax, hemp, silk and wool. In Geneva horse-chestnuts are largely consumed by grazing stock, a single sheep receiving 2 ℔ crushed morning and evening. Given to cows in moderate quantity, they have been found to enhance both the yield and flavour of milk. Deer readily eat them, and, after a preliminary steeping in lime-water, pigs also. For poultry they should be used boiled, and mixed with other nourishment. The fallen leaves are relished by sheep and deer, and afford a good litter for flocks and herds.
One variety of the horse-chestnut has variegated leaves, and another double flowers. Darwin observed that Ae. Pavia, the red buckeye of North America, shows a special tendency, under unfavourable conditions, to be double-blossomed. The seeds of this species are used to stupefy fish. The scarlet-flowered horse-chestnut, Ae. rubicunda, is a handsome tree, less in height and having a rounder head than the common form; it is a native of North America. Another species, possessing flowers with the lower petals white with a red tinge, and the upper yellow and red with a white border, and fruit unarmed, is Ae. indica, a native of the western Himalayas. Among the North American species are the foetid or Ohio buckeye, Ae. glabra, and Ae. flava, the sweet buckeye. Ae. californica, when full-grown and in flower, is a beautiful tree, but its leaves often fall before midsummer.
(2) The Spanish or sweet chestnut, Castanea sativa (natural order, Fagaceae), is a stately and magnificent tree, native of the countries bordering on the Mediterranean, but also ripening its fruit in sheltered situations as far north as Scotland. It lives very long, and attains a large size, spreading its branches widely. It has large glossy lanceolate leaves with a toothed margin. The flowers, which appear in early summer, are in pendulous, slender yellowish catkins, which bear a number of staminate flowers with a few pistillate flowers at the base. The staminate contain 8 to 20 stamens which produce an enormous amount of dusty yellow pollen, some of which gets carried by wind to the protruding stigmas of the pistillate flowers. The latter are borne three together, invested by a cupule of four green bracts, which, as the fruit matures, grow to form the tough green prickly envelope surrounding the group of generally three nuts. The largest known chestnut tree is the famous Castagno di cento cavalli, or the chestnut of a hundred horses, on the slopes of Mount Etna, a tree which, when measured about 1780 by Count Borch, was found to have a circumference of 190 ft. The timber bears a striking resemblance to that of the oak, which has been mistaken for chestnut; but it may be distinguished by the numerous fine medullary rays. Unlike oak, the wood is more valuable while young than old. When not more than fifty years old it forms durable posts for fences and gates; but at that age it often begins to deteriorate, having ring-shakes and central hollows. In a young state, when the stems are not above 2 in. in diameter at the ground, the chestnut is found to make durable hoops for casks and props for vines; and of a larger size it makes good hop-poles.
Chestnuts (the fruit of the tree) are extensively imported into Great Britain, and are eaten roasted or boiled, and mashed or otherwise as a vegetable. In a raw state they have a sweet taste, but are difficult of digestion. The trees are very abundant in the south of Europe, and chestnuts bulk largely in the food resources of the poor in Spain, Italy, Switzerland and Germany. In Italy the kernels are ground into meal, and used for thickening soups, and even for bread-making. In North America the fruits of an allied species, C. americana, are eaten both raw and cooked.
