Science Fair Project Encyclopedia
- For the Italian political alliance see Olive Tree, and the color, olive (color).
- For the part of the brain called the olive, see olivary body.
About 20, including:
The olives (Olea) are a genus of about 20 species of small trees in the family Oleaceae, very widely scattered across the Old World, from the basin of the Mediterranean Sea, southern Africa, southeast Asia north to southern China, New Caledonia and eastern Australia. They are evergreen, with small, entire leaves arranged oppositely. The fruit is a drupe.
By far the most widely known species is the European Olive, Olea europaea, which has been used since ancient times for the making of olive oil and for eating of the fruit itself (which, being bitter in its natural state, must be subjected to natural fermentation or "cured" with lye or brine to be made edible).
The wild olive is a small tree or bush of rather straggling growth, with thorny branches and opposite oblong pointed leaves, dark grayish-green above and, in the young state, hoary beneath with whitish scales; the small white flowers, with four-cleft calyx and corolla, two stamens and bifid stigma, are borne generally on the last year's wood, in racemes springing from the axils of the leaves; the drupe (fruit) is small in the wild plant, and the fleshy pericarp , which gives the cultivated olive its economic value, is comparatively thin. Cultivated forms have wide variations in character, but are generally more compact, thornless, and more prolific.
An undoubted native of Syria and the maritime parts of Asia Minor, its abundance in Greece and the islands of the Archipelago, and the frequent allusions to it by the earliest poets, seem to indicate that it was also indigenous there; but in localities remote from the Levant it may have escaped from cultivation, reverting more-or-less to its primitive type. It shows a marked preference for calcareous soils and a partiality for the sea breeze, flourishing with especial luxuriance on the limestone slopes and crags that often form the shores of the Greek peninsula and adjacent islands.
The varieties of olive known to the modern cultivator are extremely numerous. In Italy alone at least three hundred varieties have been enumerated, but only a few are grown to a large extent. The main Italian varieties are 'Leccino', 'Frantoio' and 'Carolea'. None of these can be safely identified with ancient descriptions, though it is not unlikely that some of the narrow-leaved sorts that are most esteemed may be descendants of the famed Licinian (see below). The broad-leaved olive trees of Portugal and Spain bear a larger fruit, but the pericarp has a more bitter flavor and the oil is of ranker quality. It is these Iberian olives that are usually cured and eaten, often after being pitted, stuffed (with pickled pimento, onion, or other garnishes) and jarred in fresh brine.
The olive tree, even when free increase is unchecked by pruning, is of very slow growth; but, where allowed to develop naturally over many years, the trunk sometimes attains a considerable diameter. De Candolle records one exceeding 10 meters (33 feet) in girth, the age being supposed to amount to seven centuries. Some old Italian olives have been credited with an antiquity reaching back to the first years of the empire, or even to the days of republican Rome; but the age of such ancient trees is always doubtful during growth, and their identity with old descriptions still more difficult to establish. The tree in cultivation rarely exceeds 15 meters (50 feet) in height, and in France and Italy is generally confined to much more limited dimensions by frequent pruning. The wood, of a yellow or light greenish-brown hue, is often finely veined with a darker tint, and, being very hard and close-grained, is valued by the cabinetmaker and ornamental turner.
The olive is propagated in various ways, but cuttings or layers are generally preferred; the tree roots in favorable soil almost as easily as the willow, and throws up suckers from the stump when cut down. Branches of various thickness are cut into lengths of several feet each, and, planted rather deeply in manured ground, soon vegetate; shorter pieces are sometimes laid horizontally in shallow trenches, when, covered with a few inches of soil, they rapidly throw up sucker-like shoots. In Greece and the islands grafting the cultivated tree on the wild form is a common practice. In Italy embryonic buds, which form small swellings on the stems, are carefully excised and planted beneath the surface, where they grow readily, their uovoli soon forming a vigorous shoot.
Occasionally the larger boughs are marched, and young trees thus soon obtained. The olive is also sometimes raised from seed, the oily pericarp being first softened by slight rotting, or soaking in hot water or in an alkaline solution, to facilitate germination.
The olives in the East often receive little attention from the husbandman, the branches being allowed to grow freely and without curtailment by the pruning-knife; water, however, must be supplied in long droughts to ensure a crop; with this neglectful culture the trees bear abundantly only at intervals of three or four years; thus, although wild growth is favorable to the picturesque aspect of the plantation, it is not to be recommended on economic grounds. Where the olive is carefully cultivated, as in Languedoc and Provence, it is planted in rows at regular intervals, the distance between the trees varying in different olivettes, according to the variety grown. Careful pruning is practiced, the object being to preserve the flower-bearing shoots of the preceding year, while keeping the head of the tree low, so as to allow the easy gathering of the fruit; a dome or rounded form is generally the aim of the pruner.
The spaces between the trees are occasionally manured with rotten dung or other nitrogenous matter; in France woolen rags are in high esteem for this purpose. Various annual crops are sometimes raised between the rows, and in Calabria wheat even is grown in this way; but the trees are better without any intermediate cropping. Latterly a dwarf variety, very prolific and with green fruit, has come into favor in certain localities, especially in America, where it is said to have produced a crop two or three seasons after planting. The ordinary kinds do not become profitable to the grower until from five to seven years after the cuttings are placed in the olive-ground. Apart from occasional damage by weather or organic foes, the olive crop is somewhat precarious even with the most careful cultivation, and the large untended trees so often seen in Spain and Italy do not yield that certain income to the peasant proprietor that some authors have attributed to them; the crop from these old trees is often enormous, but they seldom bear well two years in succession, and in many instances a luxuriant harvest can only be reckoned upon every sixth or seventh season.
The ripe fruit is, by the careful grower, picked by hand and deposited in cloths or baskets for conveyance to the mill; but in many parts of Spain and Greece, and generally in Asia, the olives are beaten down by poles or by shaking the boughs, or even allowed to drop naturally, often lying on the ground until the convenience of the owner admits of their removal; much of the inferior oil owes its bad quality to the carelessness of the proprietor of the trees. In southern Europe the olive harvest is in the winter months, continuing for several weeks; but the time varies in each country, and also with the season and the kinds cultivated.
The amount of oil contained in the fruit differs much in the various sorts; the pericarp usually yields from 60 to 70%. The ancient agriculturists believed that the olive would not succeed if planted more than a few leagues from the sea (Theophrastus gives 300 stadia as the limit), but modern experience does not confirm the idea, and, though showing a preference for the coast, it has long been grown far inland. A calcareous soil, however dry or poor, seems best adapted to its healthy development, though the tree will grow in any light soil, and even on clay if well drained; but, as remarked by Pliny, the plant is more liable to disease on rich soils, and the oil is inferior to the produce of the poorer and more rocky ground the species naturally affects.
The olive suffers greatly in some years from the attacks of various enemies. A fungoid growth has at times infested the trees for several successive seasons, to the great damage of the plantations. A species of coccus, Pseudomonas savastanoi pv. savastanoi induces tumor growth in the shoots, and certain lepidopterous caterpillars feed on the leaves and flowers, while the main damage is made by the olive-fly attacks to the fruit. In France and north-central Italy the olivettes suffer occasionally from frost; in the early part of the 18th century many trees were cut to the ground by a winter of exceptional severity. Gales and long-continued rains during the gathering season also cause mischief.
The genus Olea includes several other species of some economic importance. O. paniculala is a larger tree, attaining a height of 15 or 18 meters (50 or 60 feet) in the forests of Queensland, and yielding a hard and tough timber. The yet harder wood of O. laurifolia, an inhabitant of Natal, is the black ironwood of the South African colonist.
The olive in history
At what remote period of human progress the wild olive passed under the care of the husbandman and became the fruitful garden olive it is impossible to conjecture. The frequent reference in the Bible to the plant and its produce, its implied abundance in the land of Canaan, and the important place it has always held in the economy of the inhabitants of Syria, lead us to consider that country the birthplace of the cultivated olive. An improved variety, possessed at first by some small Semitic sect, it was probably slowly distributed to adjacent tribes; and, yielding profusely, with little labor, that oily matter so essential to healthy life in the dry hot climates of the East, the gift of the fruitful tree became in that primitive age a symbol of peace and goodwill among the warlike barbarians. At a later period, with the development of maritime enterprise, the oil was conveyed, as an article of trade, to the neighboring Pelagic and Ionian nations, and the plant, doubtless, soon followed.
In the Homeric world, as depicted in the Iliad, olive oil is known only as a luxury of the wealthy--an exotic product, prized chiefly for its value in the heroic toilet; the warriors anoint themselves with it after the bath, and the body of Patroclus is similarly sprinkled; but no mention of the culture of the plant is made, nor does it find any place on the Achillean shield, on which a vineyard is represented. But, although no reference to the cultivation of the olive occurs in the Iliad, the presence of the tree in the garden of Alcinous and other familiar allusions show it to have been known when the Odyssey was written. Whenever the introduction may have taken place, all tradition points to the limestone hills of Attica as the seat of its first cultivation on the Hellenic peninsula. When Poseidon and Athena contended for the future city, an olive sprang from the barren rock at the bidding of the goddess, the patron of those arts that were to bring undying influence to the rising state. That this myth has some relation to the first planting of the olive in Greece seems certain from the remarkable story told by Herodotus of the Epidaurians, who, on their crops failing, applied for counsel to the Delphic oracle, and were enjoined to erect statues to Damia and Auxesia (symbols of fertility) carved from the wood of the true garden olive, then possessed only by the Athenians, who granted their request for a tree on condition of their making an annual sacrifice to Athena, its patron; they thus obeyed the command of the Pythian, and their lands became again fertile. The sacred tree of the goddess long stood on the Acropolis, and, though destroyed in the Persian invasion, sprouted again from the root--some suckers of which were said to have produced those olive trees of the Academy in an after age no less revered.
By the time of Solon the olive had so spread that he found it necessary to enact laws to regulate the cultivation of the tree in Attica, from which country it was probably distributed gradually to all the Athenian allies and tributary states. To the Ionian coast, where it abounded in the time of Thales, it may have been in an earlier age brought by Phoenician vessels; some of the Sporades may have received it from the same source; the olives of Rhodes and Crete had perhaps a similar origin. Samos, if we may judge from the epithet of Aeschylus, must have had the fruitful plant long before the Persian Wars.
Yielding a grateful substitute for the butter and animal fats consumed by the races of the north, the olive, among the southern nations of antiquity, became an emblem not only of peace but of national wealth and domestic plenty; the branches borne in the Panathenaea, the wild olive spray of the Olympic victor, the olive crown of the Roman conqueror at ovation, and those of the equites at their imperial review alike typified gifts of peace that, in a barbarous age, could be secured by victory alone. Among the Greeks the oil was valued as an important article of diet, as well as for its external use. The Roman people employed it largely in food and cookery--the wealthy as an indispensable adjunct to the toilet; and in the luxurious days of the later empire it became a favorite axiom that long and pleasant life depended on two fluids, wine within and oil without. Pliny vaguely describes fifteen varieties of olive cultivated in his day, that called the Licinian being held in most esteem, and the oil obtained from it at Venafrum in Campania the finest known to Roman connoisseurs; the produce of Istria and Baetica was regarded as second only to that of the Italian peninsula.
The gourmet of the empire valued the unripe fruit, steeped in brine, as a provocative to the palate, no less than his modern representative; and pickled olives, retaining their characteristic flavor, have been found among the buried stores of Pompeii. The bitter juice or refuse deposited during expression of the oil (called amurca), and the astringent leaves of the tree have many virtues attributed to them by ancient authors. The oil of the bitter wild olive was employed by the Roman physicians in medicine, but does not appear ever to have been used as food or in the culinary art.
In modern times the olive has been spread widely over the world; and, though the Mediterranean lands that were its ancient home still yield the chief supply of the oil, the tree is now cultivated successfully in many regions unknown to its early distributors. Protected by high brick walls, a fruiting olive tree is in the Chelsea Physic Garden, London. Soon after the discovery of the Americas it was conveyed thither by the Spanish settlers. In Chile it flourishes as luxuriantly as in its native land, the trunk sometimes becoming of large girth, while oil of fair quality is yielded by the fruit. To Peru it was carried at a later date, but has not there been equally successful. Introduced into Mexico by the Jesuit missionaries of the 17th century, it was planted by similar agency in Upper California, where it stagnated under the careless management of the Anglo-Saxon conqueror. Olive cultivation has also been attempted in the south-eastern states, especially in South Carolina, Florida and Mississippi. In the eastern hemisphere the olive has been established in many inland districts which would have been anciently considered ill-adapted for its culture. To Armenia and Persia it was known at a comparatively early period of history, and many olive-yards now exist in Upper Egypt. The tree has been introduced into Chinese agriculture, and has become an important addition to the resources of the Australian planter. In Queensland the olive has found a climate specially suited to its wants; in South Australia, near Adelaide, it also grows vigorously; and there are probably few coast districts of the vast island continent where the tree would not flourish. It has likewise been successfully introduced into some parts of Cape Colony.
The olive is used in different culinary disciplines: In mixed drinks it is the famous garnish of the martini; in sausages, it may be used in mortadella and so on. It is commonly used in breads as well.
Cultivation of the olive is a key characteristic of Mediterranean mixed farming, and played a large part in the economic development of ancient Greece because of the suitability of olive oil as an export crop. For instance Attica, the region of Athens, was a grain importer and olive oil exporter from early historic times. The Athenian pottery industry was stimulated largely by the demand for containers in which to export olive oil.
Note also that the green olive and black olive are the same plant; green olives are pickled before ripened, where black olives are pickled after being ripened.
- Picholine olives
- Lucques olives
- Image of Olea europaea from 'Flora von Deutschland Österreich und der Schweiz'
- Resource portal for olive oil
- Olive at plants for a future
- "Olives 101" from Lindsay, an American distributer.
- Olive farming, olive oil and olives in Spain The history, geography and gastronomy of the olive in Spain.
- Olive farming, olive oil and olives in France The history, geography and gastronomy of the olive in France.
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