CLOVES are the unexpanded flower buds of Eugenia Caryophyllata of Caryophyllus Aromaticus, a tree belonging to the natural order Myrtacca, and are named from the French word clou, signifying nail, which it sometimes resembles.

The French word, Girofle Cloux de Girofle; German, Gewurzuelken; Persian, Meykuk; Sanskrit, Lavunga; Arabia, Kerunful; Bengalle, Lung; Malay, Chankee, Lawang; Portuguese, Cravos da India; Chinese, Thenghio; Java, Wohkayu, Lawang; Hindoo, Laung.

It is indigenous to the Molucca or, as they are frequently called, the “Spice Islands.” It was originally confined to five of these islands, viz: Tidor, Ternate, Motir, Batian, and Kian, but chiefly to the last. These constitute a string of islands westward of the large island Gilalo and, strange to say, the clove tree does not appear to do well on the large islands, such as Gilalo and Ceram and Celebes. It is probable that Booro and the Xula Isles constitute about the western limit of the successful culture of the clove. Although it is a native of small islands, it will not do well too near the sea where it receives much moisture, or at a high elevation where it is cold. Sloping loam land is best, where there is no stagnant water, 1,000 feet elevation being the limit.

The clove tree is found outside the Moluccas and Amboina, Haruka, Saparua, and Naesalaut in the following places: Guiana, Zanzibar, Pemba, Java, Sumatra, Reunion, and West Indies islands.

There are five varieties of cloves as follows:

The first three are about equally valuable as spices, the female being considered best for distillation of essential oil, while the wild clove has very little aromatic flavor and no value but for adulteration.

The royal clove is a curious monstrosity, which formerly had a great reputation as the Caryophyllum regium, by reason of its rarity, and the curious observations which are made respecting it. It is a very small clove and is distinguished by an abnormal number of sepals and by large bracts at the base of the tubes of the calyx. The corolla and internal organs are imperfectly developed. In commerce the cloves are known and named from the places of growth and are graded in value in the order named—Penang (Fig. 3), Bencoolen (Fig. 4), Amboina (Fig. 2), Zanzibar (Fig. 1). They do not exhibit any very decided structural difference, but it takes 4,500 Penang cloves to weigh one pound and 5,000 Zanzibar for same weight. There also enters into commerce as a secondary product clove stalks and mother’s cloves, the latter being the dried ripe fruit. Cloves were one of the principal Oriental spices, being the basis of a rich trade from an early part of the Christian era, and the spice was well known to the ancients and certainly formed an article of commerce, during the Middle Ages, when Alleppo was the grand mart of Eastern trade.

The Portuguese discovered cloves growing abundantly on the Molucca Islands about the year 1600 and they held possession of the principal clove trade for nearly a century. Previous to this time, cloves were brought to Europe from ports in the Mediterranean, where they had been brought by Arabians, Persians, and Egyptians.

About 1605, the Portuguese were driven from the Moluccas by the Dutch, who endeavored to control the clove trade by attempting to extirpate all the clove trees growing in their native islands, and to confine the culture of the entire production to the islands of Amboina and Ternate, paying the kings of the islands of Ternate, Tidor, and Batian a tribute to permit and assist in the extirpation of the trees.

In the years 1769 and 1771, the French, under M. Poivre, made two expeditions to the Moluccas and found the clove tree growing in some small islands which had been overlooked by the Dutch. From one of these (Guebi) they obtained plants and transplanted them to the Isle of France. In 1785, there were already between 10,000 and 11,000 clove trees growing in this island. At the end of the seventeenth century, an Arab carried the clove seed from Baurbou and planted the plantation in Zanzibar at Miltoni, on the road to Cheuni, and plants were conveyed from the Isle of France to Cayenne, Dominica, and to Mauritius. About 1770, the English put such a high duty on spices in Dominica that they ruined the trade there, and although M. Buee planted the clove tree there over 100 years ago, one tree is yet living.

Meanwhile the Dutch, who favored the one principal isle, Amboina, selecting that part of it called Leytimeer and the adjoining Uliasser Islands, divided Amboina into 4,000 allotments. Each of these divisions was expected to afford sufficient space for the growth of 125 trees, and it was ordered that this number should be cultivated.

In 1720, a law was passed rendering it compulsory on the natives to make up the full complement, and accordingly 500,000 clove trees flourished within the limit of the small island, their annual aggregate product amounting to more than 1,000,000 pounds of cloves. One can scarcely imagine the beauty of these immense groves with their pinkish-white, snowdrop blossoms, the sweet perfumes of which are carried by the gentle breezes far out to sea.

The clove tree, owing to its noble height, fine form, and luxuriant foliage, is attractive in appearance. Its bark is thin and smooth and its wood exceedingly hard, but it has a grayish color, which unfits it for cabinet work. It is an evergreen and in its natural state grows to a height of from thirty to forty feet, with a straight trunk, making it the most beautiful of all known trees. When four feet high, the tree spreads into several branches with fork stems, on which leaves grow directly opposite each other. The leaves are long, ovate and smooth, narrow and indented on the edge, pointed and of a thick consistency. The color of the upper surface inclines to red, as also does the stalk, while the under surface is green. The entire tree is strongly aromatic and the petioles of the leaves have nearly the same pungency as the calyces of the flowers.

In cultivating cloves, the mother cloves are best selected fresh, as they soon lose their vitality. The fruit seed (called by the natives paleny), which have become fertilized by remaining and ripening on the trees, are first soaked in water three days, or until they begin to germinate, and are next planted in a nursery of rich mold with bud end above ground in shaded beds, six inches apart if many plants are needed, twelve inches apart for few.

Two seeds are planted in each hill in the trenches, to provide for the failure of a part of the seed to germinate, and care must be taken not to plant the seed more than two inches below the surface. The nursery beds are made about six feet wide and of any length desired, and are shaded by a flat framework of sticks three to three and one-half feet high, over which is placed grass or cocoanut leaves. The ground is watered every morning and evening by taking water in the hand from the watering pot until the seeds have developed. When the plants appear above ground they are watered every other day, and when about six inches high every ten days.

The plants are kept in the shaded beds for nine months or one year, when they will be about one foot high. After this they are gradually left to the exposure of the sun by removing the framework for one or two months, when they are transplanted. Great care is taken in moving the plants. The transplanting takes place in the rainy season. The soil is first cut around the plant by a knife or triangular-shaped spade called “moaa,” “jembe,” or hoe, and the plant is lifted with as much soil adhering to it as possible and is placed across two banana strips of fiber, which are three to four inches wide and one to two feet long. The four ends of these strips are wrapped around the plants and firmly tied together, and in that way the plants are carried to the place for planting. Before planting, the pieces of fiber are cut beneath at each corner and the plant is placed in holes dug for them, which are about thirty feet apart; the earth is heaped around them and the balance of the fiber at the top is removed. The plant is watered every day if it is very dry weather, and at intervals for a year, or until it is about eighteen inches high.

A great many plants usually die out and continually replanting is necessary. For this reason, a nursery is kept for about five years.

After the clove garden is planted there is no need of shading, but as the trees have only a slight hold in the ground, they are easily destroyed. They should be planted in sheltered situations. For example, a hurricane which visited Zanzibar in 1872 destroyed nine-tenths of the clove groves, but the adjoining island of Pemba did not suffer nearly so much, especially on the west side of the island, which was fairly well protected. For this reason the clove trees are protected by belted double rows of casuarina and cerbera trees. Cocoanut trees are also planted at irregular places among the clove trees. The slaves, who have their own small orchards, often plant cassava, cocoanut, and mangoes with the clove not only for shelter but to secure extra crops from the other trees. In Amboina the young trees are planted in old clove orchards for shelter, and when the young trees grow up the old trees are cut down. A clayey substratum, dark yellow or volcanic earth, intermingled with gravel and dark loam, with a small amount of sand to reduce its tenacity, is the best soil. Marshy soil is fatal. Plants obtained from a garden of self-sown seeds are the best, but sometimes young branches are laid down and kept moist, when they will take root in about six months. Clove trees after being well rooted require but little care, and as the clove tree attracts much moisture, little other herbage will grow beneath it, but they must be kept well weeded or the trees will run into wild cloves. New leaves form in the wet season in May, the old leaves dropping off as new ones come, and soon after the leaves are out the germ of fruit is discovered and the tree begins to bear.

The clove tree needs no pruning with the exception of topping, and no manuring except by leaves which fall from the trees, which are very good fertilizers.

The flowers are of a delicate pink color and grow at the extremity of the branches. There are from nine to fifteen flowers in a cluster. These clusters, or branched peduncles, are arranged in tricahatomous terminal cymes, jointed to the branches. The unexpanded corolla forms a ball on the top of the bud between four of the calyces. The calyx is elongated and to it the ovary is united. It tapers downward and is the cup of the unripe fruit seed, giving the seed the resemblance of the clove (garafa, which is no doubt a corruption of the French word girofle).

As soon as the corolla begins to fade the calyx changes its color, first to yellow and green (Fig. 6), and then to red (Fig. 5), and, together with the embryo seed, which is about the size of a small pea, is at this stage of its growth the clove of commerce and is ready for harvesting. If it is allowed to remain on the tree three weeks longer it will gradually swell, forming an oblong berry containing one or two cells and as many seeds. It is then ripe, and is known as the mother clove (by the native, paleng). It has then lost the pungent property of the clove and will have entirely lost its value as a spice, and is valuable only for seed.

The clove, then, we find composed of two parts. The part we use is the flower clove. It is about six-tenths of an inch in length. It has a long cylindrical calyx, dividing above into four pointed spreading sepals, which surround four petals or leaves that are the unexpanded flowers. Thus the filaments are rolled into a globular bud or head of the clove, which is about two-tenth of an inch in diameter. The parts may be seen by soaking the clove in water, when the leaves will soften and unroll. The petals are of a light color on account of their numerous oil cells, which spring from the base of a four-sided epigynous disc with angles directed towards the lobes of the calyx. The stamens are very numerous, being inserted at the base of the petals and arched over the style, which is short and sublate and rises from depressions in the center of the disc. Immediately below it, and united with the upper portion of the calyx, is the ovary, which is two-celled and contains many ovules.

The lower end of the calyx (hypanthium) has a compressed form, is solid, but has internal tissues which are far more porous than the walls, the whole calyx being of a deep, rich brown color. It has a dull, wrinkled surface and dense, fleshy texture, and abounds in essential oil which exudes on a simple pressure of the finger nail.

The clove tree is not subject to any fungoid disease, but it suffers from a caterpillar which often strips the leaves in dry weather, but the tree will soon recover after the rain sets in. The white ant also attacks the root. No remedy is undertaken for either of these pests. A worm also insinuates itself into the wood and thousands of trees sometimes perish from its work.

Harvesting should begin as soon as the fruit is at the proper stage and should be rushed with as much haste as is possible, or much of the crop may be lost by over-ripening. As all buds do not mature at one time, it takes about three weeks to complete the harvest.

Cloths are first spread on the ground beneath the tree. The fruit must be picked mostly by hand. Although the twigs are easily broken, the harvesting is very tedious. Four-sided ladders or movable stages are used for the lower limbs and seed poles for beating the fruit from the upper branches, which cannot be reached from the ladders. The limbs of the tree are so brittle that great care must be taken not to break them, lest the crop for the next year be injured. Boys and girls from ten to fourteen years old, are the best help for gathering the fruit. The clove and clove stems are both gathered at the same time, and are dried on mats to prevent fermentation. Those which fall from the tree are dried in the sunshine. They have a shriveled appearance, dull color, little essential oil, and are of inferior value. The flowers are next dried, when they assume the brown color of the clove. The finest cloves are dark-brown with a full, perfect head free from moisture. The inferior are smaller and poorer in essential oil. The drying process is usually by simple exposure to the sun for several days on mats, but in some places the flowers are smoked on hurdles covered with matting near a slow fire. In a few cases they have been scalded in hot water before smoking. After the drying process, they are ready for packing, if they are brittle or readily break between the fingers.

Cloves are now exported in large amounts from Zanzibar and its neighboring island Pemba, twenty miles distant. They are cultivated there by all classes, from the Sultan to the humblest of his subjects. Zanzibar cloves, being very dry, do not lose much in weight by drying and may be stored for some time and will not mold, but the Pemba production arrives in a damp condition and must be sold or milled at once to save loss from shortage. The Zanzibar cloves are larger than the Pemba variety and have a reddish head by which they may be known, while the dry Pemba cloves, by reason of the greater amount of moisture they contain, have a darker color. The Zanzibar cloves, being well cultivated, are very fine, but the Pemba, having more rains, have an advantage over the Zanzibar in quantity, but they are lacking in quality. Zanzibar Island is fifty miles long by twenty miles wide, and alone produces 7,000,000 pounds of cloves annually, and Pemba a much larger quantity. Pemba is divided into two districts, Weti in the north and Chaki in the south. The two islands produce 90 per cent. of all the cloves raised in the world.

Whole cloves have a great affinity for water. Some exporters have taken advantage of the fact by attempting to place their sacks in a position aboard vessels where they may imbibe water and increase their weight, much to the detriment of the clove.

Cloves in their natural state lose from 50 to 60 per cent. in drying. One frasila of thirty-five pounds of freshly gathered cloves is equal to but half a frasila when dried. The difference in shortage between cloves at Zanzibar and on their arrival in Europe is about 8 per cent. Only about two-thirds of a clove garden is depended on for bearing, one-third being allowed for barren young trees. The tree in its native islands begins to bear when from four to five years old and is at its prime at twelve years; but in Amboina and other Molucca islands, Haruka, Saparua, and Naesalaut, it does not bear much until it is from ten to twelve years old, and it requires much more attention.

The tree yields but one crop each year, which, on an average, is about seven pounds. A good healthy orchard at maturity produces about 375 pounds to the acre, less one-third for young trees, or about 300 pounds. The yield is often fifteen to twenty pounds to a tree, and we have records of trees which bore as high as seventy-five pounds at the age of 150 years. The ordinary life of a tree is from twenty to thirty years, though it varies much in different localities. When the clove tree becomes old and worthless for bearing it will have a ragged appearance.

Cloves are shipped to native ports in hides and are sometimes exported in sacks made from split cocoanut leaves, containing 133? pounds each, called “piculs,” also in twenty-two-pound packages called “kilos.” They are more often exported in double mats in bags called “frales,” of eighty to 100 pounds (called by the natives “mankunda”). These bags are preferred to gunny sacks, though there is more shortage, a fact which is strangely marked, since the mats, though double, admit a large amount of dampness.

The average annual consumption of cloves throughout the world has been estimated at 11,000,000 pounds. No cloves were exported from Singapore in the year 1904, but the city of Penang exported in that year $7,373.91 worth, and Colombo, Ceylon, exported 115 hundred weight of cloves and mace in the same year. A transverse section of the lower part of a clove shows a dark rhomboid zone, the tissue on either side of which is of a lighter hue, which is chiefly made up of about thirty fibro-vascular bundles, another stronger bundle traversing the center of the clove. The outer layer of this, beneath the epidermis and belonging to it, we find to be a debris of no apparent structure, consisting of numerous cells and fibro-vascular bundles within their spiral vessels, with deep shreds of brown cellular matter attached. There are also tissues bordering on the oil cells. These cells are frequently as many as 300 micro-millimeters in diameter.

About 200 oil cells may be counted in one transverse section, so that the large amount of essential oil in the drug is well shown by its microscopic character. Pollen grains and sometimes whole anthers are present and concretions of oxalate of lime.

The fibro-vascular bundles, as well as the tissues bordering on the oil cells, assume a greenish-black hue on coming in contact with alcoholic perchloride of iron. Oil cells are largely distributed in the leaves and petals but no starch is found in them.

The clove is very rich in essential oil, containing a greater proportion than any other plant. The oil has a greater specific gravity than water and, therefore, sinks in it. Water extracts very little of the flavor of cloves. The oil combined with resinous matter in cloves gives them their pungency, and their aromatic property depends on the amount of oil they contain.

In studying the structure of both the whole or the powdered cloves, an examination for starch in the powder should first be made in water, as the starch granules swell by the use of the chloral-hydrate solution. This solution must be used, however, as the sections and fragments will not be transparent without it.

Cloves are ground on common burr stone, but great care must be taken in grinding since they contain so much oil. The best powdered cloves present a rich meal of reddish-brown color and are a good preventive of moths, but they deteriorate very rapidly. The natives of China and India use cloves to flavor their rice; the oil is also used for medicinal purposes. Cloves, stems, and leaves are shipped in large quantities from Zanzibar for adulterating the powdered clove and are called “vikunia”; by the native, “swahil”; French, “griffers de girofle,” “peduncles de girofle”; Italy, “fustiand bastoreni”; Latin, “stiptes caryophylli.” They form a dull, gray-colored powder and yield only 5 to 6 per cent. of volatile oil, and, of course, have only a corresponding percentage of the strength or value of the true clove (the root yields 0.04 per cent.). On account of their near appearance in color and flavor to the powdered clove, and particularly for their cheapness, they are much sought for by the miller of spices, as he can thus sell his mixture at a price much below the market value of the true powdered clove. This adulterant may be easily detected by the microscope, which will reveal their thick-walled, hard, flinty stone cells and long, yellow, fibrous tissue, as similar structures are not found in the cloves in such abundance. The fruit of the clove, if added, contains starch granules, which are not present in the meal of the leaves and stems. Often the essential oil is pressed from the whole cloves and they are then rubbed in oil between the hands and mixed with cloves which drop from the trees; both are then mixed with good cloves, and all are sold as prime stock. They are, however, easily detected by their pale color and shrunken appearance and lack of pungency. On one occasion several bags of artificial whole cloves arrived in London from Zanzibar, neatly manufactured by machinery from soft deal wood stained a dark color and soaked in a solution of essence of cloves to give them the required scent. Upon investigation it was found that this manufactured article had been imported into Zanzibar from America.

A great many flowers of plants contain the flavor or perfumes of cloves. Among these are the flowers of the lettsomia bana-nox, called by the natives of Bangal “kulmiluta.” The flowers which are produced in rainy seasons are large and pure white, expanding at sunset with a strong flavor of cloves, but they wither at sunrise. Sometimes the flower buds of Dicypellium caryophyllatum of Brazil, which has a bark called clove cassia, are used as substitute for cloves (also called Brazilian clove bark).

Cloves are largely adulterated with roasted rye and when the price of cloves is high, pimento or Jamaica pepper is often used as a mixture. This adulterant may be detected by the microscope by reason of the thick walls of the cells, which are not present in cloves, as well as by the quantity of starch granules which are not visible in the ground clove.

The essential oil of cloves is a mixture of two oils, one a hydrocarbon isomeric with oil of turpentine and the other an oxygenated oil eugenol or eugenic acid, which possesses the taste and odor of cloves, depending on the amount of eugenol it contains. This amount may be estimated by separation as follows: Shake three parts of the oil with a solution composed of one part caustic potash or soda in ten parts of water; press the crystalline paste of eugenol alkali which forms; take off the press residue with water; decompose with hydrochloric acid; wash the liberated eugenol with water, dry it with calcium chloride and then rectify.

Clove oil is often adulterated with phenol. This adulterant may be detected by shaking the oil with fifty times its volume of hot water; after cooling, it is decanted and concentrated at a gentle heat to a small bulk; then a drop of liquid ammonia and a pinch of chloride are dropped on the surface; if phenol is present the liquor will assume a green color, which changes to a blue shade, which will remain for a number of days; if not adulterated, no coloration will be produced. Clove oil is first colorless, or yellow, and darkens with age and by exposure to the air. It consists of sesquialteral and an oxygenated oil, the first passing over with vapor of water, called “light oil of cloves.”

When the crude oil is distilled with strong potash of lye, its composition is C₁₅H₂₄, specific gravity 0.190 at 15 degrees C., its boiling point 251 degrees to 254 degrees C., its optical power being very light.

The other, which is the eugenol, is the chief constituent. Its composition is C₁₀H₁₂O₂. This constituent exists to the extent of 76 to 85 per cent., while very fine may contain 90.64 per cent. in the oil of cloves, in direct proportion to the quality of the product.

Good oil of cloves should have a specific gravity of 1.067 at 15 degrees C., and should be freely soluble in alcohol at 90 per cent. An adulteration by turpentine would lower the specific gravity and diminish the solubility in alcohol. Eugenol is a strongly refractive liquid with the characteristic smell and the burning taste of cloves, and by exposure to the air it becomes brown; on fusion with caustic potash it yields protocatechuic acid convertible into vanillin by action of potassium permanganate. Eugenol is also found in pimento and in the leaves of cinnamon and of many other trees and has been artificially produced by the action of sodium amalgam on coniferyl alcohol. Pure eugenol has a specific gravity of 1.072 at 15 degrees; its boiling point is 253 degrees to 243 degrees C., and it forms a clear solution in 1 per cent. of caustic potash solution.

Clove oil has been found to contain some salicylic acid, which gives the greenish blue coloration when it is brought in contact with an alcoholic solution of perchloride of iron, and produces the intense violet color when it is agitated with metallic reduced iron. This acid may be isolated by agitating the oil with a solution of carbonate of ammonia. Caryophyllin (C₁₀H₁₈O), a neutral, tasteless, inodorous substance, isomeric with common camphor, crystallizable in prismatic needles, has also been found in cloves by extracting with ether cloves previously deprived of the greater part of their essential oil by a little alcohol.

Cloves also contain 16 per cent. of a peculiar tannic acid, 13 per cent. of gum, and about 18 per cent. of water and extractive matter.

The chemical composition of cloves differs to quite an extent in the different countries where they grow—Amboina, 19 per cent.; Zanzibar, 17.5 per cent.

Coffee oil is least volatile of any essential oil and is obtained from the flower buds and the flower stalks of cloves by aqueous distillation. This distillation is largely carried on in England, and the proportion of oil may amount to 16 or 20 per cent., but, to extract the whole, distillation must be long continued; the water being returned to the same material. The oil is a colorless or yellowish liquid like all clove oil, with a powerful odor and flavor of cloves, varying in specific gravity from 1.046 to 1.058. It combines well with grease, soap, and spirits, and is largely used in perfumery, and in Germany it is often adulterated with carbolic acid (phenol).