The word olive derives from Latin ŏlīva 'olive fruit; olive tree',^[14] possibly through Etruscan 𐌀𐌅𐌉𐌄𐌋𐌄 (eleiva) from the archaic Proto-Greek form *ἐλαίϝα (*elaíwa) (Classic Greek ἐλαία elaía 'olive fruit; olive tree').^[15][16] The word oil originally meant 'olive oil', from ŏlĕum,^[17] ἔλαιον (élaion 'olive oil').^[18][19] The word for 'oil' in multiple other languages also ultimately derives from the name of this tree and its fruit. The oldest attested forms of the Greek words are Mycenaean 𐀁𐀨𐀷, e-ra-wa, and 𐀁𐀨𐀺, e-ra-wo or 𐀁𐁉𐀺, e-rai-wo, written in the Linear B syllabic script.^[20]

The olive tree, Olea europaea, is an evergreen tree or shrub native to Mediterranean Europe, Asia, and Africa. It is short and squat and rarely exceeds 8–15 m (25–50 ft) in height. Pisciottana—a unique variety comprising 40,000 trees found only in the area around Pisciotta in the Campania region of southern Italy—often exceeds this, with correspondingly large trunk diameters. The silvery green leaves are oblong, measuring 4–10 cm (1+1⁄2–4 in) long and 1–3 cm (3⁄8–1+3⁄16 in) wide. The trunk is typically gnarled and twisted.^[21]

Small, white flowers are borne generally on the previous year's wood, in racemes springing from leaf axils. Each flower is made of four yellowish white petals fused at the bottom joined to a base of four fused green sepals. The flower buds grow slowly from 4 to 6 weeks before they reach a length of about 2 cm and bloom, they bloom quicker between 5-6 days in hot weather and 2 weeks in colder areas. The flowers also pollinate and fertilize faster in hotter climates.^[22]

The fruit is a small drupe, 1–2.5 cm (3⁄8–1 in) long when ripe, thinner-fleshed and smaller in wild plants than in orchard cultivars. Olives are harvested in the green to purple stage.^[23] O. europaea contains a pyrena commonly referred to in American English as a "pit", and in British English as a "stone".^[24]

The six natural subspecies of Olea europaea are distributed over a wide range:^[25][26][27]

• O. e. subsp. europaea (Mediterranean Basin)

The subspecies europaea is divided into two varieties, the europaea, which was formerly named Olea sativa, with the seedlings called "olivasters", and silvestris, which corresponds to the old wildly growing Mediterranean species O. oleaster, with the seedlings called "oleasters".^[28] The sylvestris is characterized by a smaller, shrubby tree that produces smaller fruits and leaves.^[29]

• O. e. subsp. cuspidata (from South Africa throughout East Africa ,Arabia, Northwest India to Southwest China)
• O. e. subsp. cerasiformis (Madeira); also known as Olea maderensis
• O. e. subsp. guanchica (Canary Islands)
• O. e. subsp. laperrinei (Algeria, Sudan, Niger)
• O. e. subsp. maroccana (Morocco)

The subspecies O. e. cerasiformis is tetraploid, and O. e. maroccana is hexaploid.^[30] Wild-growing forms of the olive are sometimes treated as the species Olea oleaster, or "oleaster". The trees referred to as "white" and "black" olives in Southeast Asia are not actually olives but species of Canarium.^[31]

Hundreds of cultivars of the olive tree are known.^[32][33] An olive's cultivar has a significant impact on its colour, size, shape, and growth characteristics, as well as the qualities of olive oil.^[32] Olive cultivars may be used primarily for oil, eating, or both. Olives cultivated for consumption are generally referred to as "table olives".^[13]

Since many olive cultivars are self-sterile or nearly so, they are generally planted in pairs with a single primary cultivar and a secondary cultivar selected for its ability to fertilize the primary one. In recent times, efforts have been directed at producing hybrid cultivars with qualities useful to farmers, such as resistance to disease,^[34] quick growth, and larger or more consistent crops.^{[citation needed]}

As one of the oldest cultivated trees on Earth,^[35] the history of the olive is deeply intertwined with humans; its ecological success and expansion is largely the result of human activity rather than environmental conditions, with the tree's genetic and geographic trajectory directly reflecting the rise and fall of several civilizations.^[36] Owing to this deep relationship with humans, the olive has been disseminated well beyond its native range, spanning 28.6 million acres across 66 countries.^[37] There were an estimated 865 million olive trees in the world in 2005, of which the vast majority were found in Mediterranean countries; traditionally marginal areas accounted for no more than 25% of olive-planted area and 10% of oil production.^[38]

Fossil evidence indicates that the olive tree had its origins 20–40 million years ago in the Oligocene, in what now corresponds to Italy and the eastern Mediterranean Basin.^[39][40] Around 100,000 years ago, olives were used by humans in Africa, on the Atlantic coast of Morocco, for fuel and most probably for consumption.^[41] Wild olive trees, or oleasters, have been collected in the Eastern Mediterranean since approximately 19,000 BP;^[42] the genome of cultivated olives reflects their origin from oleaster populations in the region.^{[43][44][45][46][47][48]}

The olive plant was first cultivated in the Mediterranean between 8,000 and 6,000 years ago.^[3][39][49] Domestication likely began in the Levant, based on archeological findings in ancient tombs—including written tablets, olive pits, and olive wood fragments—as well as genetic analyses.^[50][51][3]

For thousands of years, olives were grown primarily for lamp oil rather than for culinary purposes,^[50] as the natural fruit has an extremely bitter taste.^[52] It is very likely that the first mechanized agricultural methods and tools were those designed to produce olive oil;^[53] the earliest olive oil production dates back some 6,500 years ago in coastal Canaan (present-day Israel).^[54] As far back as 3000 BC, olives were grown commercially in Crete and may have been the main source of wealth for the Minoan civilization.^[55]

The exact ancestry of the cultivated olive is unknown. Fossil olea pollen has been found in Macedonia and other places around the Mediterranean, indicating that this genus is an original element of the Mediterranean flora. Fossilized leaves of olea were found in the palaeosols of the volcanic Greek island of Santorini and dated to about 37,000 BP. Imprints of larvae of olive whitefly Aleurobus olivinus were found on the leaves. The same insect is commonly found today on olive leaves, showing that the plant-animal co-evolutionary relations have not changed since that time.^[56] Other leaves found on the same island date back to 60,000 BP, making them the oldest known olives from the Mediterranean.^[57]

In the 16th century BC, the Phoenicians—a seafaring people native to the Levantine heartland where olives likely were first cultivated—started disseminating the olive throughout the Mediterranean. Owing to their dominance as traders, merchants, and mariners, they succeeded in spreading the olive to the Greek isles, particularly Crete, later introducing it to the Greek mainland between the 14th and 12th centuries BC. Olive cultivation increased and gained great importance among the Greeks; Athenian statesman Solon (c. 630 – c. 560 BC) issued decrees regulating olive planting and encouraging its cultivation, particularly for export.^[58] Greek literature and mythology reflected the privileged and even sacred position of the olive, while leading thinkers and figures like Hippocrates, Homer, and Theophrastus observed its various positive properties and benefits.

The earliest evidence of the olive tree in Egypt traces back to the Eighteenth Dynasty (1570–1345 BC),^[59] during the same period the Phoenicians began distributing it across the Mediterranean. However, scenes on the walls of the tomb of King Teti (ruled c. 2345 BC to c. 2333 BC) show olive fruits and trees, though it is unclear if these represent domestic cultivation. Pharoah Ramses III (reigned 1186–1155 BC) promoted cultivating olive trees and offered the olive oil extracted from Heliopolis to the Sun God Ra; papyrus manuscripts dated to his reign (c. 1550 BC), as well as temple engravings, depict the growing of olive trees and the use of olive oil in cooking, lamps, cosmetics, medicine and embalming. Pharoah Tutankhamun, who ruled from ca. 1333 to 1323 BC, wore a garland of olive branches originated from Dakhla Oasis, 360 km to the east. Egyptian mummies dating back to the 20-25th dynasties (c. 1185 BC to c. 656 BC) have also been found wearing olive wreaths.

While there is no evidence of olive cultivation in Mesopotamia, olive wood appears as early as the mid third millennium BC; the site of Emar in present-day Syria has olive wood and olive pits dating to the Middle Bronze Age (2000–1600 BC).^[60] The Code of Hammurabi, a compilation of laws and edicts made by King Hammurabi of the Old Babylonian Empire (reigning from c. 1792 to c. 1750 BC), makes repeated references to olive oil as a key commodity.^[61] The Assyrian Empire (858–627 BC) may have expanded into the southern Levant partly to secure control over its lucrative olive oil production.^[62]

From the sixth century BC onwards, the olive continued spreading toward the central and western Mediterranean through colonization and commerce, reaching Sicily, Libya, and Tunisia. From there, it expanded into southern Italy among the various Etruscan, Sabine, and Italic peoples. The introduction of the olive tree to mainland Italy allegedly occurred during the reign of Lucius Tarquinius Priscus (616–578 BC), possibly from Tripoli (Libya) or Gabes (Tunisia). Cultivation moved as far upwards as Liguria near the border with France. When the Romans arrived in North Africa beginning in the second half of the first century BC, the native Berbers knew how to graft wild olives and had highly developed its cultivation throughout the region.

The olive's expansion and cultivation reached its greatest extent through Rome's gradual conquest and settlement across virtually the entire Mediterranean; the Romans continued propagating the olive for commercial and agricultural purposes, as well as to assimilate local populations. It was introduced in present-day Marseille around 600 BC and spread from there to the whole of Gaul (modern France). The olive tree made its appearance in Sardinia following Roman conquest in the third century BC, though it may not have reached nearby Corsica until after the fall of the western Roman Empire in the fifth century AD.

Although olive growing was introduced to Spain by the Phoenicians some time in 1050 BC, it did not reach a larger scale until the arrival of Scipio (212 BC) during the Second Punic War against Carthage. After the Third Punic War (149–146 BC), olives occupied a large stretch of the Baetica valley in southwest Spain and spread towards the central and Mediterranean coastal areas of the Iberian Peninsula, including Portugal. Through the second century AD, this region would become the largest source of olives and olive oil within the empire.^[63] Olive became a core part of the Roman diet, and by extension a major economic pillar; the cultivation, harvesting, and trade in olives and their derived goods sustained many livelihoods and regions. The emperor Hadrian (117–138 AD) passed laws prompting olive cultivation by exempting individuals who grew olive trees from rent payments on their land for ten years.^[63]

The degree to which the olive benefited from the Romans is demonstrated by the significant decline in olive planting and olive oil production that followed the collapse of the Roman Empire.^[64] Beginning in the early eighth century AD, Muslim Arabs and North Africans brought their own varieties of olives during their conquest of Iberia, reinvigorating and expanding olive growing throughout the peninsula. The spread and importance of olives during subsequent Islamic rule is reflected in the Arabic roots of the Spanish words for olive (aceituna), oil (aceite), and wild olive tree (acebuche) and the Portuguese words for olive (azeitona) and olive oil (azeite).

The olive is not native outside the Mediterranean Basin, although various wild subspecies are endemic throughout Sub-Saharan Africa, southern Arabia, and central and south Asia.^[65] Beyond its immediate native range, the cultivated olive historically spread across West Asia through southwest China, and into parts of southern Egypt, northeast Sudan, the Canary Islands, and possibly the mountains of the Sahara.^[65] Olive domestication is present on every inhabited continent due to human introduction.

Spanish colonists brought the olive to the New World in the 18th century, where its cultivation prospered in present-day Peru, Chile, Uruguay and Argentina. The first seedlings from Spain were planted in Lima by Antonio de Rivera in 1560. Olive tree cultivation quickly spread along the valleys of South America's dry Pacific coast where the climate is similar to the Mediterranean.^[66]

Spanish missionaries established the olive tree in California between 1769 and 1795 at Mission San Diego de Alcalá. Orchards were started at other missions, but by 1838, only two olive orchards were confirmed in California. Cultivation for oil gradually became a highly successful commercial venture from the 1860s onward.^[67][68]

Olive growing in the United States is primarily concentrated in warmer regions like California, Texas,^[69] New Mexico, Arizona, Georgia, and Florida. California is by far the largest olive producer in the U.S., accounting for 95 percent of domestic olives;^[70] as of 2021, there are roughly 36,000 acres under olive cultivation in the U.S.,^[70] of which about 35,000 acres are in California.^[71] However, the industry is also expanding into the southeastern U.S., with Florida and Georgia experiencing growth in olive farming.^[72][70]

Olive trees were successfully introduced in Japan in 1908 on Shodo Island; located in the Seto Inland Sea, the island has a moderate climate characterized by stable year-round temperature and relatively low rainfall. It became the cradle of olive cultivation in Japan,^[73] accounting for over 95% of the country's total production,^[74] and earning the nickname "Olive Island".^[75] Olives play a central role in the local culture and economy, with the island's mascot and tourism merchandise reflecting olive themes.^[75] Olive cultivation has spread to other regions in Japan, namely neighboring Kagawa and Okayama and nearby Kyushu.^[74] The vast majority of Japanese growers are small-scale farmers.^[74]

Since 2010,^[76] Pakistan has been pursuing large scale commercial olive production, which it identified as a strategic national priority to reduce dependence on foreign oils and expand economic opportunity.^[77] As part of the national Ten Billion Tree Tsunami Project launched in 2019, which aimed to plant 10 billion trees to mitigate climate change and environmental degradation,^[78] the Khyber Pakhtunkhwa provincial government planted thousands of olives to symbolize peace and provide commercial opportunities in the war-torn region.^[79] By 2020, with the help of experts from Spain and Italy, Pakistan imported thousands of trees and identified 10 million acres for growing olives.^[80] The following year, the federal Ministry of Climate Change launched the Olive Trees Tsunami Project to plant nearly 10 million hectares of olive trees. In 2022, Pakistan announced its intention to join the International Olive Council as part of ongoing efforts to develop its domestic olive industry.^[81] As of January 2025, the country had 5.6 million cultivated olive trees, with 500,000 to 800,000 new trees planted annually, as well as 80 million wild olive trees.^[82] Punjab province plans to plant 50 million olive trees on about 9.8 million acres by 2026.^[82]

Commercial olive oil production started in India in 2016, following the planting of olive saplings imported from Israel in Rajasthan's Thar Desert in 2008.^[83] Production was spearheaded by Rajasthan Olive Cultivation Limited, a state government-funded agency that offered subsidies and incentives for growing olives, with support from Israeli experts.^[84] Olive farms continued expanding into 2020 but saw a precipitous decline in size and production volume by 2023, due to the difficult climate and declining government interest and support.^[85]

Amid ongoing climate warming, several small-scale olive production farms have also been established at fairly high latitudes in Europe and North America since the early 21st century, including in the United Kingdom, Germany, and Canada.^{[86][87][88][89]}

Modern researchers and historians have identified the olive as one of the defining characteristics of both ancient and contemporary Mediterranean culture, geography, and cuisine.^[90][91] Georges Duhamel remarked that the "Mediterranean ends where the olive tree no longer grows".^[92]

Olives are thought to have been domesticated in the third millennium BC at the latest, at which point they, along with grain and grapes, became part of Colin Renfrew's Mediterranean triad of staple crops that fueled the emergence of more complex societies.^[8] Olives, and especially (perfumed) olive oil, became a major export product during the Minoan and Mycenaean periods. Dutch archaeologist Jorrit Kelder proposed that the Mycenaeans sent shipments of olive oil, probably alongside live olive branches, to the court of Egyptian pharaoh Akhenaten as a diplomatic gift.^[93] In Egypt, these imported olive branches may have acquired ritual meanings, as they are depicted as offerings on the wall of the Aten temple and were used in wreaths for the burial of Tutankhamun. It is likely that, as well as being used for culinary purposes, olive oil had various other purposes, including as a perfume.^[94]

The ancient Greeks smeared olive oil on their bodies and hair as a matter of grooming and good health. Olive oil was used to anoint kings and athletes in ancient Greece. It was burnt in the sacred lamps of temples and was the "eternal flame" of the original Olympic games, whose victors were crowned with its leaves. The olive appears frequently, and often prominently, in ancient Greek literature. Homer's Odyssey (c. eighth century BC), Odysseus crawls beneath two shoots of olive that grow from a single stock,^[95] and in the Iliad, (XVII.53ff) there is a metaphoric description of a lone olive tree in the mountains by a spring; the Greeks observed that the olive rarely thrives at a distance from the sea, which in Greece invariably means up mountain slopes. Greek myth attributed to the primordial culture-hero Aristaeus the understanding of olive husbandry, along with cheese-making and beekeeping.^[96] Olive was one of the woods used to fashion the most primitive Greek cult figures, called xoana, referring to their wooden material; they were reverently preserved for centuries.^[97]

In an archaic Athenian foundation myth, Athena won the patronage of Attica from Poseidon with the gift of the olive. According to the fourth-century BC father of botany, Theophrastus, olive trees ordinarily attained an age around 200 years,^[98] and he mentions that the very olive tree of Athena still grew on the Acropolis; it was still to be seen there in the second century AD,^[99] and when Pausanias was shown it c. 170 AD, he reported "Legend also says that when the Persians fired Athens the olive was burnt down, but on the very day it was burnt it grew again to the height of two cubits."^[100] Because olive suckers sprout readily from the stump, and some existing olive trees are purportedly many centuries old, it is possible that the olive tree of the Acropolis dated to the Bronze Age. The olive remained sacred to Athens and its patron deity Athena, appearing on its coinage. According to another myth, Elaea—whose name translates to "olive"—was an accomplished athlete killed by fellow athletes out of envy; owing to her impressive achievement, Athena and Gaia turn her into an olive tree as a reward.^[101]

The olive and its properties were subject to early scientific and empirical observation. Theophrastus, in On the Causes of Plants, states that the cultivated olive must be vegetatively propagated; indeed, the pits give rise to thorny, wild-type olives, spread far and wide by birds. He also reports how the bearing olive can be grafted on the wild olive, for which the Greeks had a separate name, kotinos.^[102] In his Enquiry into Plants, Theophrastus states that the olive can be propagated from a piece of the trunk, the root, a twig, or a stake.^[103] Homer described olive oil as "liquid gold", while Hippocrates (c. 460 BC – c. 375 BC), widely regarded as the father of medicine, considered it "the great healer".^[104]

Ancient Egyptians believed that Isis, the consort of Osiris and the mother of university, taught mankind to extract oil from olives; olive oil has been found among valuable treasures buried in the tombs of important prehistoric Egyptians, and was used as an offering to the gods.

Like the Greeks, the Romans held olives in high regard for various purposes, both practical and symbolic. Roman mythology held that Hercules introduced the olive tree to Italy from North Africa, while the goddess of wisdom, Minerva, taught the art of cultivation and oil extraction.^[105] Numerous archaeological finds indicate the presence of the olive tree in Lazio, the region around Rome, as early as the 7th century BC; however, rudimentary olive production has also been traced back to earlier Etruscan and Sabine settlements in the area.^[105]

The olive tree was subject to many treatises and agronomic works by the Romans. Pliny the Elder, in his first century AD encyclopedia, Naturalis Historia, describes at least 22 different varieties and qualities of olive trees, detailing their respective techniques for cultivation and production. Pliny also observes that an olive tree is one of only three plants—along with a vine and fig tree—growing in the middle of the Roman Forum, which served as the center of daily life in the city; the olive was purportedly planted to provide shade. (The garden was recreated in the 20th century).^[106]

Roman poet Horace mentions the olive in reference to his own diet, which he describes as very simple: "As for me, olives, endives, and smooth mallows provide sustenance."^[107] Roman architect and engineer Vitruvius describes of the use of charred olive wood in tying together walls and foundations in his De Architectura.^[108] Olive cultivation and production was also recognized for its commercial and economic importance; according to Cato the Younger, among the various tasks of the pater familias (the family patriarch and head of household) was that of keeping an account of the olive oil. The city of Rome designated a special area for negotiating and selling olive oil that was managed by negotiatores oleari, who were analogous to stockbrokers.^[109]

Olives were one of the main elements in ancient Israelite cuisine. Olive oil was used not only culinarily, but also for lighting, sacrificial offerings, ointment, and anointing religious and political officials.^[110] The word moshiach—Hebrew for Messiah—means "anointed one"; in Jewish eschatology, the Messiah is a future Jewish king from the Davidic line, who is expected to be anointed with holy oil partially derived from olive oil. The olive tree is one of the first plants mentioned in the Hebrew Bible, and one of the most significant; an olive branch (or leaf, depending on translation) was brought back to Noah by a dove to demonstrate that the flood was over (Genesis 8:11).^[111]

The olive's importance in Israel is expressed in the parable of Jotham in Judges 9:8–9:^[112] "One day the trees went out to anoint a king for themselves. They said to the olive tree, 'Be our king.' But the olive tree answered, 'Should I give up my oil, by which both gods and humans are honored, to hold sway over the trees?'"^[112] The olive tree is also analogized to a righteous man (Psalm 52:8; Hosea 14:6) whose "children will be like vigorous young olive trees" (Psalm 128:3).

Deuteronomy characterizes the "Promised Land" of the Hebrews as containing olive groves (6:11) and subsequently lists olives as one of the seven species that are special products of the Land of Israel (8:8).^[113][112] According to the Halakha, the Jewish law mandatory for all Jews, the olive is one of the seven species that require the recitation of me'eyn shalosh, a blessing of gratitude, after they are consumed. Olive oil is also the most recommended and best possible oil for lighting Shabbat candles.^[114]

Olive oil features prominently in the Jewish festival of Hanukkah, which commemorates the recovery of Jerusalem and subsequent rededication of the Second Temple during the Maccabean Revolt against the Seleucid Empire in the 2nd century BC. According to the Talmud, the central text of Rabbinical Judaism, after Seleucid forces had been driven from the Temple, the Maccabees discovered that almost all the ritual olive oil for the Temple menorah had been profaned. They found only single container with just enough pure oil to keep the menorah lit for a single day; however, it burned for eight days—the time needed for new oil to have been prepared—a miracle that forms a major part of Hanukkah celebrations. Subsequently, the olive tree and its oil have come to represent the strength and persistence of the Jewish people.^[115] In common with other Mediterranean cultures, the Jewish people used it for many practical and ritualistic purposes, from fuel and medicine to cosmetics and even currency; as in Greek and Roman societies, athletes were cleansed by covering their skin with oil then scraping it to remove the dirt. Jews who settled in foreign lands often became olive merchants.^[115]

Due to its importance in the Hebrew Bible, the olive has significant national meaning in modern Israeli culture. Two olive branches appear as part of Israel's emblem, which may have been inspired by the vision of biblical Hebrew prophet Zechariah, who describes seeing a menorah flanked by an olive tree on each side;^[116] the trees represent Zerubbabel and Joshua, the governor and high priest, respectively. The olive tree was declared the unofficial national tree of Israel in 2021 by a survey of Israelis;^[117] it is often planted during Tu BiShvat and its fruit is a customary part of the accompanying seder.

The olive tree, as well as its fruit and oil, play an important role in Christianity.^[118] Apart from being mentioned in the Hebrew Bible (the Christian Old Testament), they appear several times in the New Testament. The Mount of Olives east of Jerusalem figures prominently in the Bible: It is part of the route to Bethany, which is the site of several key biblical events; where Jesus stood when he wept over Jerusalem; and where he ascended to heaven (Acts 1:9–12). Jesus is said to have spent time on the mount, teaching and prophesying to his disciples (Matthew 24–25)—most notably the Olivet Discourse—and returning after each day to rest (Luke 21:37, and John 8:1).

Gethsemane, an olive garden at the foot of the Mount of Olives, whose name derives from the Hebrew word for "oil press",^[119] is where Jesus underwent his agonized prayer to God and was ultimately betrayed and arrested before his crucifixion. According to Eastern Orthodox Church tradition, it is where the Virgin Mary was buried and was assumed into heaven after her dormition on Mount Zion.^[120] Gethsemane became a focal point for Christian pilgrims during the Middle Ages and remains revered in Christianity; many of its olive trees, which are purportedly among the oldest living trees in the world,^[121] are divided among various churches.

The apostle Paul uses the olive tree as an allegory in his Epistle to the Romans, comparing Israelites to a tame olive tree and Gentiles to a wild olive branch (Romans 11:17–24).The cultivated olive tree is pruned and nurtured so as to bear fruit, whereas its barren branches are trimmed and discarded; God has preserved the holy root of Israel so that the wild branches (the Gentiles) can be grafted onto it and thus share in the blessings of the cultivated tree (Israel)

The olive tree and olive oil are mentioned seven times in the Quran;^[122] it is one of a handful of plants to appear by name, along with the fig, date palm, ginger, and grapevine. The olive is praised as a precious fruit and a gift from God (Surah Al-An'am: 99). Muhammad is reported to have said: "Take oil of olive and massage with it—it is a blessed tree" (Sunan al-Darimi, 69:103). Olives are substitutes for dates (if not available) during Ramadan fasting, and olive tree leaves are used as incense in some Muslim Mediterranean countries.^[123]

In Palestine, the olive tree carries symbolic connotations of resilience, health, ancestral ties, and community.^[124][125] Researchers have found that it represents many Palestinian cultural values such as Sutra, A'wana and Sumud.^[126][124] Olive trees are also a symbol of Palestinian identity: ^[124][126] they are viewed as the first witnesses that Palestine is the homeland of the Palestinian people, and signify the bond between Palestinians and their land.^[124] The olive tree is a means of survival and security,^[127] serving as the primary source of income for over 800,000 families and accounting for 14 percent of the Palestinian economy.^[128] Almost half the cultivated land in the West Bank is planted with about 10 million olive trees.^[129]

The harvest season is referred to as "Palestine's wedding" and is considered a national holiday when schools close for two days so that pupils and teachers can join in the harvest.^[126] This holiday allows community and family members to gather and serves as a ritual that encompasses their values surrounding family, labour, community and aid for other members of the community that do not possess land.^[126] This is practised through the tradition of leaving fruit on a tree during the harvest so that those who do not have land and are unable to take part in the harvest can still reap the benefits.^[126]

The olive tree's enduring cultural and economic significance to the Palestinians has put it at the center of the ongoing Israeli–Palestinian conflict; an estimated 800,000 olive trees have been uprooted by Israeli authorities and settlers since 1967,^[130] and groves are frequently targeted in attacks or acts of vandalism.^[131][132] These destructions are considered a way to forcibly displace Palestinians and seize their land.^[133]

During the early stage of the American Revolutionary War, the Second Continental Congress of the Thirteen American Colonies issued the "Olive Branch Petition" to Great Britain to prevent further escalation. The Great Seal of the United States, first used in 1782, depicts an eagle clutching an olive branch and arrows in its talons, indicating the power of peace and war, respectively.^[134] The eagle is portrayed as casting its gaze towards the olive branch, symbolizing the United States' preference to pursue peace before war.^[135]

Thomas Jefferson, a founding father and third president of the United States, was a great admirer of olives and olive oil, regarding the olive tree as "the richest gift of heaven", "one of the most precious productions of nature", and "the most interesting plant in existence".^[136] Jefferson's fascination stemmed from his experiences in Europe, particularly France and Italy, while serving as the U.S. Minister to France in the late 1780s. He was impressed by the olive tree's resilience and suitability for various climates, taking detailed notes of its various "virtues" and qualities; he also observed the widespread use of olive oil and encouraged its consumption for its health benefits and ability to provide "a proper and comfortable nourishment" compared to existing staples in the U.S. such as rice.^[137]

Jefferson believed the olive tree would be a valuable crop in America and could help alleviate poverty and improve the lives of enslaved people; he wrote letters to various agricultural societies urging them to consider introducing olive cultivation in the U.S., advocating for "an olive tree planted for every American slave", particularly in the American South.^[137] Jefferson experimented with growing olive trees at his home in Monticello, Virginia and attempted to establish a domestic olive oil industry,^[136] expressing bitter disappointment when this effort failed in the early 1810s.

Jefferson remained a lifelong connoisseur of olive oil, which "had joined the exclusive company of wine and books as a ... 'necessary of life'"; every year until his death, he imported four to five gallons of "virgin oil of Aix" from France, and at least one fragment of an olive oil bottle has been unearthed at Monticello.^[138]

The flag of the United Nations adopted in 1946 is a world map surrounded by two olive branches.^[139] Likewise, a similar design is adopted for the flags of many U.N. agencies and programs, including the International Atomic Energy Agency, International Labour Organization, and World Health Organization.

The olive tree, Olea europaea, has been cultivated for the olive fruit, olive oil, fine wood, olive leaf, and ornamental reasons. About 80% of all harvested olives are turned into oil, while about 20% are used as table olives.^[32] The olive is one of the "trinity" or "triad" of basic ingredients in Mediterranean cuisine, along with wheat (for bread, pasta, and couscous) and the grape (for wine).^[140][141]

Olive oil is a liquid fat obtained from olives, produced by pressing whole olives and extracting the resulting oil. It is most commonly used for culinary purposes, namely frying, marinating, or flavoring food or as a salad dressing. Olive oil is also used in cosmetics, pharmaceuticals, soaps, and as a fuel for traditional oil lamps. Olive oil serves a ritual purpose in some religions. Pursuant to historical tradition, various Christian churches use olive oil as part of consecration ceremonies, such as administering certain sacraments and ecclesiastical functions.^[142]

Spain accounts for almost half of global olive oil production; other major producers are Portugal, Italy, Tunisia, Greece and Turkey.^[143] Per capita consumption is highest in Greece, followed by Italy and Spain.^[144]

The composition of olive oil varies with the cultivar, elevation, time of harvest and extraction process. It consists mainly of oleic acid (up to 83%), with smaller amounts of other fatty acids including linoleic acid (up to 21%) and palmitic acid (up to 20%). Extra virgin olive oil (EVOO) is required to have no more than 0.8% free acidity and fruity flavor characteristics.^[145]

Table olives

Table olives are classified by the International Olive Council (IOC) into three groups according to the degree of ripeness achieved before harvesting:^[146]

1. Green olives are picked when they have obtained full size, while unripe; they are usually shades of green to yellow and contain the bitter phytochemical oleuropein.^[146]
2. Semi-ripe or turning-colour olives are picked at the beginning of the ripening cycle, when the colour has begun to change from green to multicolour shades of red to brown. Only the skin is coloured, as the flesh of the fruit lacks pigmentation at this stage, unlike that of ripe olives.
3. Black olives or ripe olives are picked at full maturity when fully ripe, displaying colours of purple, brown or black.^{[146][page needed]} To leach the oleuropein from olives, commercial producers use lye, which neutralizes the bitterness of oleuropein, producing a mild flavour and soft texture characteristic of California black olives sold in cans.^[146] Such olives are typically preserved in brine and sterilized under high heat during the canning process.^[147]

Raw or fresh olives are naturally very bitter and astringent; to make them palatable, olives must be cured and fermented, thereby removing oleuropein, a bitter phenolic compound that can reach levels of 14% of dry matter in young olives.^[148] In addition to oleuropein, other phenolic compounds render freshly picked olives unpalatable and must also be removed or lowered in quantity through curing and fermentation. Generally speaking, phenolics reach their peak in young fruit and are converted as the fruit matures.^[149] Once ripening occurs, the levels of phenolics sharply decline through their conversion to other organic products, which render some cultivars edible immediately.^[148] One example of an edible olive native to the island of Thasos is the throubes black olive, which becomes edible when allowed to ripen in the sun, shrivel, and fall from the tree.^[150][151]

The curing process may take from a few days with lye, to a few months with brine or salt packing.^[152] With the exception of California style and salt-cured olives, all methods of curing involve a major fermentation involving bacteria and yeast that is of equal importance to the final table olive product.^[153] Traditional cures, using the natural microflora on the fruit to induce fermentation, lead to two important outcomes: the leaching out and breakdown of oleuropein and other unpalatable phenolic compounds, and the generation of favourable metabolites from bacteria and yeast, such as organic acids, probiotics, glycerol, and esters, which affect the sensory properties of the final table olives.^[148] Mixed bacterial/yeast olive fermentations may have probiotic qualities.^[154][155] Lactic acid is the most important metabolite, as it lowers the pH, acting as a natural preservative against the growth of unwanted pathogenic species. The result is table olives which can be stored without refrigeration. Fermentations dominated by lactic acid bacteria are, therefore, the most suitable method of curing olives. Yeast-dominated fermentations produce a different suite of metabolites which provide poorer preservation, so they are corrected with an acid such as citric acid in the final processing stage to provide microbial stability.^[13]

The many types of preparations for table olives depend on local tastes and traditions. The most important commercial examples are listed below.

• Lebanese or Phoenician fermentation: Applied to green, semiripe, or ripe olives. Olives are soaked in salt water for 24–48 hours. Then they are slightly crushed with a rock to hasten the fermentation process. The olives are stored for a period of up to a year in a container with salt water, lemon juice, lemon peels, laurel and olive leaves, and rosemary. Some recipes may contain white vinegar or olive oil.^{[citation needed]}
• Spanish or Sevillian fermentation: Most commonly applied to green olive preparation, around 60% of all the world's table olives are produced with this method.^[156] Olives are soaked in lye (dilute NaOH, 2–4%) for 8–10 hours to hydrolyse the oleuropein. They are usually considered "treated" when the lye has penetrated two-thirds of the way into the fruit. They are then washed once or several times in water to remove the caustic solution and transferred to fermenting vessels full of brine at typical concentrations of 8–12% NaCl.^[157] The brine is changed on a regular basis to help remove the phenolic compounds. ^{[citation needed]}
• Fermentation is carried out by the natural microbiota present on the olives that survive the lye treatment process. Many organisms are involved, usually reflecting the local conditions or terroir of the olives. During a typical fermentation gram-negative enterobacteria flourish in small numbers at first but are rapidly outgrown by lactic acid bacteria species such as Leuconostoc mesenteroides, Lactobacillus plantarum, Lactobacillus brevis and Pediococcus damnosus. These bacteria produce lactic acid to help lower the pH of the brine and therefore stabilize the product against unwanted pathogenic species. A diversity of yeasts then accumulate in sufficient numbers to help complete the fermentation alongside the lactic acid bacteria. Yeasts commonly mentioned include the teleomorphs Pichia anomala, Pichia membranifaciens, Debaryomyces hansenii and Kluyveromyces marxianus.^[13]
• Once fermented, the olives are placed in fresh brine and acid corrected, to be ready for market.^{[citation needed]}
• Sicilian or Greek fermentation: Applied to green, semiripe and ripe olives, they are almost identical to the Spanish type fermentation process, but the lye treatment process is skipped and the olives are placed directly in fermentation vessels full of brine (8–12% NaCl). The brine is changed on a regular basis to help remove the phenolic compounds. As the caustic treatment is avoided, lactic acid bacteria are only present in similar numbers to yeast and appear to be outdone by the abundant yeasts found on untreated olives. As very little acid is produced by the yeast fermentation, lactic, acetic, or citric acid is often added to the fermentation stage to stabilize the process.^[153]
• Picholine or directly brined fermentation: Applied to green, semi-ripe, or ripe olives, they are soaked in lye typically for longer periods than Spanish style (e.g. 10–72 hours) until the solution has penetrated three-quarters of the way into the fruit. They are then washed and immediately brined and acid corrected with citric acid to achieve microbial stability. Fermentation still occurs carried out by acidogenic yeast and bacteria but is more subdued than other methods. The brine is changed on a regular basis to help remove the phenolic compounds, and a series of progressively stronger concentrations of salt are added until the product is fully stabilized and ready to be eaten.^[13]
• Water-cured fermentation: Applied to green, semi-ripe, or ripe olives, these are soaked in water or weak brine and this solution is changed on a daily basis for 10–14 days. The oleuropein is naturally dissolved and leached into the water and removed during a continual soak-wash cycle. Fermentation takes place during the water treatment stage and involves a mixed yeast/bacteria ecosystem. Sometimes, the olives are lightly cracked with a blunt instrument to trigger fermentation and speed up the fermentation process. Once debittered, the olives are brined to concentrations of 8–12% NaCl and acid corrected and are then ready to eat.^[153]
• Salt-cured fermentation: Applied only to ripe olives, since it is only a light fermentation. They are usually produced in Morocco, Turkey, and other eastern Mediterranean countries. Once picked, the olives are vigorously washed and packed in alternating layers with salt. The high concentration of salt draws the moisture out of olives, dehydrating and shriveling them until they look somewhat analogous to a raisin. Once packed in salt, fermentation is minimal and only initiated by the most halophilic yeast species such as Debaryomyces hansenii. Once cured, they are sold in their natural state without any additives.^[13] So-called oil-cured olives are cured in salt and then soaked in oil.^[158]
• California or artificial ripening: Applied to green and semi-ripe olives, they are placed in lye and soaked. Upon their removal, they are washed in water injected with compressed air, without fermentation. This process is repeated several times until both oxygen and lye have soaked through to the pit. The repeated, saturated exposure to air oxidises the skin and flesh of the fruit, turning it black in an artificial process that mimics natural ripening. Once fully oxidised or "blackened", they are brined and acid corrected and are then ready for eating.^[146][147]

Olive wood is very hard and tough and is prized for its durability, colour, high combustion temperature, and interesting grain patterns. Because of the commercial importance of the fruit, slow growth, and relatively small size of the tree, olive wood and its products are relatively expensive. Common uses of olive wood include kitchen utensils, carved wooden bowls, cutting boards, fine furniture, and decorative items. The yellow or light greenish-brown wood is often finely veined with a darker tint; being very hard and close-grained, it is valued by woodworkers.^[159]

In modern landscape design, olive trees are frequently used as ornamental features for their distinctively gnarled trunks and evergreen silvery-gray foliage.^[160] Smaller cultivars have become increasingly popular as indoor plants due to their resilience and aesthetic appeal.^[161]

The pressing of olives to create olive oil results in a liquid byproduct known in Latin as amurca or olive mill wastewater. Owing to its bitterness and unpleasant aroma, it was historically discarded as a waste product.^[162]

The hard, inedible core of the olive fruit, also known as the pit or kernel, has various potential applications, including for biofuel, activated carbon (used for water filtration and absorption),^[163] furfural production, filler, animal feed, or resin formation.^[164] Spain, the world's leading olive grower, produces about 400,000 tons of olive pits annually, which are mostly used as biomass for residential boilers, olive mills, and some industries.^[165]

Olive tree cultivation has been linked to promoting biodiversity, improving soil quality,^[166] and mitigating climate change through carbon sequestration.^[167][168] As long-lived perennial plants, they absorb carbon dioxide over long time frames, with groves sequestering approximately 2.2 to 4.5 metric tons of carbon dioxide (CO2) per hectare annually.^[169][170]

The earliest evidence for the domestication of olives comes from the Chalcolithic period archaeological site of Teleilat el Ghassul in modern Jordan. Farmers in ancient times believed that olive trees would not grow well if planted more than a certain distance from the sea; Theophrastus gives 300 stadia (55.6 km or 34.5 mi) as the limit. Modern experience does not always confirm this, and, though showing a preference for the coast, they have long been grown further inland in some areas with suitable climates, particularly in the southwestern Mediterranean (Iberia and northwest Africa) where winters are mild. An article on olive tree cultivation in Spain is brought down in Ibn al-'Awwam's 12th-century agricultural work, Book on Agriculture.^[172]

Olives are cultivated in many regions of the world with Mediterranean climates, such as South Africa, Chile, Peru, Pakistan, Australia, and the western United States (particularly California), as well as in areas with temperate climates such as New Zealand and the Córdoba Province, Argentina.^[173][174]

Olive trees show a marked preference for calcareous soils, flourishing best on limestone slopes and crags, and coastal climate conditions. They grow in any light soil, even on clay if well drained, but in rich soils, they are predisposed to disease and produce poor quality oil. (This was noted by Pliny the Elder.) Olives like hot weather and sunny positions without any shade, while temperatures below −10 °C (14 °F) may injure even a mature tree. They tolerate drought well because of their sturdy and extensive root systems. Olive trees can remain productive for centuries as long as they are pruned correctly and regularly.^[175]

Only a handful of olive varieties can be used to cross-pollinate. 'Pendolino' olive trees are partially self-fertile, but pollenizers are needed for a large fruit crop. Other compatible olive tree pollinators include 'Leccino' and 'Maurino'. 'Pendolino' olive trees are used extensively as pollinizers in large olive tree groves.^[176]

Olives are propagated by various methods. The preferred ways are cuttings and layers; the tree roots easily in favourable soil and throws up suckers from the stump when cut down. However, yields from trees grown from suckers or seeds are poor; they must be budded or grafted onto other specimens to do well.^[177] Branches of various thickness cut into lengths around 1 m (3+1⁄2 ft) planted deeply in manured ground soon vegetate. Shorter pieces are sometimes laid horizontally in shallow trenches and, when covered with a few centimetres of soil, rapidly throw up sucker-like shoots. In Greece, grafting the cultivated tree on the wild tree is a common practice. In Italy, embryonic buds, which form small swellings on the stems, are carefully excised and planted under the soil surface, where they soon form a vigorous shoot.^{[citation needed]}

The olive is also sometimes grown from seed. To facilitate germination, the oily pericarp is first softened by slight rotting, or soaked in hot water or in an alkaline solution.^{[citation needed]}

In situations where extreme cold has damaged or killed the olive tree, the rootstock can survive and produce new shoots which in turn become new trees. In this way, olive trees can regenerate themselves. In Tuscany in 1985, a very severe frost destroyed many productive and aged olive trees and ruined many farmers' livelihoods.^[178] However, new shoots appeared in the spring and, once the dead wood was removed, became the basis for new fruit-producing trees.^{[citation needed]}

Olives grow very slowly, and over many years, the trunk can attain a considerable diameter. A. P. de Candolle recorded one exceeding 10 m (33 ft) in girth. The trees rarely exceed 15 m (50 ft) in height and are generally confined to much more limited dimensions by frequent pruning. Olives are very hardy and are resistant to disease and fire. Its root system is robust and capable of regenerating the tree even if the above-ground structure is destroyed. ^{[citation needed]}

The crop from old trees is sometimes enormous, but they seldom bear well two years in succession, and in many cases, a large harvest occurs every sixth or seventh season. Where the olive is carefully cultivated, as in Liguria, Languedoc, and Provence, the trees are regularly pruned. The pruning preserves the flower-bearing shoots of the preceding year, while keeping the tree low enough to allow the easy gathering of the fruit.

Various pathologies can affect olives. The most serious pest is the olive fruit fly (Dacus oleae or Bactrocera oleae) which lays its eggs in the olive most commonly just before it becomes ripe in the autumn. The region surrounding the puncture rots, becomes brown, and takes a bitter taste, making the olive unfit for eating or for oil. For controlling the pest, the practice has been to spray with insecticides (organophosphates, e.g. dimethoate). Classic organic methods have been applied such as trapping, applying the bacterium Bacillus thuringiensis, and spraying with kaolin. Such methods are obligatory for organic olives.^{[citation needed]}

A fungus, Cycloconium oleaginum, can infect the trees for several successive seasons, causing great damage to plantations. A species of bacterium, Pseudomonas savastanoi pv. oleae,^[179] induces tumour growth in the shoots. Certain lepidopterous caterpillars feed on the leaves and flowers. Xylella fastidiosa bacteria, which can also infect citrus fruit and vines, has attacked olive trees in Apulia, southern Italy, causing olive quick decline syndrome (OQDS).^{[180][181][182]} The main vector is Philaenus spumarius (meadow spittlebug).^[183]

A pest that spreads through olive trees is the black scale bug, a small black scale insect that resembles a small black spot. They attach themselves firmly to olive trees and reduce the quality of the fruit; their main predators are wasps. The curculio beetle eats the edges of leaves, leaving sawtooth damage.^[184]

Rabbits eat the bark of olive trees and can do considerable damage, especially to young trees. If the bark is removed around the entire circumference of a tree, it is likely to die. Voles and mice also do damage by eating the roots. At the northern edge of their cultivation zone, for instance in northern Italy, southern France and Switzerland, olive trees suffer occasionally from frost.^[185] Gales and long-continued rains during the gathering season also cause damage. In the colder Mediterranean hinterland, olive cultivation is replaced by other fruits, typically the chestnut.^[186]

Since its first domestication, O. europaea has been spreading back to the wild from planted groves. Its original wild populations in southern Europe have been largely swamped by feral plants.^[187]

In some other parts of the world where it has been introduced, most notably South Australia, the olive has become a major weed that displaces native vegetation. In South Australia, its seeds are spread by the introduced red fox and by many bird species, including the European starling and the native emu, into woodlands, where they germinate and eventually form a dense canopy that prevents regeneration of native trees.^[188] As the climate of South Australia is very dry and bushfire prone, the oil-rich feral olive tree substantially increases the fire hazard of native sclerophyll woodlands.^[189]

Olives are harvested in the autumn and winter. More specifically in the Northern Hemisphere, green olives are picked from the end of September to about the middle of November. In the Southern Hemisphere, green olives are picked from the middle of October to the end of November, and black olives are collected worldwide from the middle of November to the end of January or early February. In southern Europe, harvesting is done for several weeks in winter, but the time varies in each country, and with the season and the cultivar.^{[citation needed]} Large olive trees produce on average about 400 pounds of olives annually.

Most olives today are harvested by shaking the boughs or the whole tree. Using olives found lying on the ground can result in poor quality oil, due to damage. Another method involves standing on a ladder and "milking" the olives into a sack tied around the harvester's waist. This method produces high quality oil.^[190] A third method uses a device called an oli-net that wraps around the tree trunk and opens to form an umbrella-like catcher from which workers collect the fruit. Another method uses an electric tool with large tongs that spin around quickly, removing fruit from the tree.

Table olive varieties are more difficult to harvest, as workers must take care not to damage the fruit; baskets that hang around the worker's neck are used. In some places in Italy, Croatia, and Greece, olives are harvested by hand because the terrain is too mountainous for machines. As a result, the fruit is not bruised, which leads to a superior finished product. The method also involves sawing off branches, which is healthy for future production.^[149]

The amount of oil contained in the fruit differs greatly by cultivar; the pericarp is usually 60–70% oil. Typical yields are 1.5–2.2 kg (3 lb 5 oz – 4 lb 14 oz) of oil per tree per year.^[191]

Olive trees have been venerated for their resilience and longevity since antiquity; several specimens are reputed to be several thousand years old. However, compared to other woody plants, the exact lifespan is difficult to determine through common methods like dendrochronology (analyzing tree rings) due to the olive tree's irregular growth patterns, which can include missing annual tree rings, hollowed-out interiors, and multiple trunks.^[192] For example, a 2013 study revealed wide disparities among different laboratories conducting tree-ring dating of the same specimens.^[193] Alternatively, although age can be inferred from a tree's diameter, this method is imperfect due to a range of other factors that affect size and length, such as soil fertility and climatic conditions.^[194] Based on a combination of tree-ring and radiocarbon dating, olive trees have maximum ages between 300 and 500 years,^[195] with some research finding that most of the oldest trees live up to 700 years.^[196]

• An olive tree in Mouriscas, Abrantes, Portugal, Oliveira do Mouchão, is one of the oldest known olive trees still alive to this day, with an estimated age of 3,350 years,^[197][198] planted approximately at the beginning of the Atlantic Bronze Age.
• An olive tree in the city of Bar in Montenegro has an estimated age of between 2,014 and 2,480 years.^[199]
• An olive tree on the island of Brijuni in Croatia has a radiocarbon dating age of about 1,600 years. It still gives fruit (about 30 kg or 66 lb per year), which is made into olive oil.^[200]
• An olive tree in west Athens, named Plato's Olive Tree, is thought to be a remnant of the grove where Plato's Academy was situated, making it an estimated 2,400 years old.^[201] The tree consisted of a cavernous trunk from which a few branches were still sprouting in 1975 when a traffic accident caused a bus to uproot it.^[201] Following that the trunk was preserved and displayed in the nearby Agricultural University of Athens.
• The age of an olive tree in Crete, the Finix Olive, is claimed to be more than 2,000 years, based on archaeological evidence around the tree.^[191]
• The olive tree of Vouves in Crete has an age estimated at between 2,000 and 4,000 years.^[202]
• An olive tree called Farga d'Arió in Ulldecona, Catalonia, Spain, has been estimated (with laser-perimetry methods) to date back to 314 AD, which would mean that it was planted when Constantine the Great was Roman emperor.^[203]
• Some Italian olive trees are believed to date back to Ancient Rome (8th century BC to 5th century AD), although identifying progenitor trees in ancient sources is difficult. There are other trees about 1,000 years old in the same garden. The 15th-century trees of Olivo della Linza, at Alliste in the Province of Lecce in Apulia on the Italian mainland, were noted by Bishop Ludovico de Pennis during his pastoral visit to the Diocese of Nardò-Gallipoli in 1452.^[204]
• The village of Bcheale, Lebanon, claims to have the oldest olive trees in the world (4000 BC for the oldest), but no scientific study conclusively supports these claims. Research published in 2024 determined that at least one tree was over 1,100 years, while most others were around 500 years old.^[205] Trees in the towns of Amioun appear to be at least 1,500 years old.^[206][207]
• Several trees in the Garden of Gethsemane (from the Hebrew words gat shemanim or olive press) in Jerusalem are claimed to date back to the time of Jesus.^[208] A study conducted by the National Research Council of Italy in 2012 used carbon dating on older parts of the trunks of three trees from Gethsemane and came up with the dates of 1092, 1166 and 1198 AD, while DNA tests show that the trees were originally planted from the same parent plant.^[209] According to molecular analysis, the tested trees showed the same allelic profile at all microsatellite loci analyzed, which furthermore may indicate attempt to keep the lineage of an older species intact.^[210] However, Bernabei writes, "All the tree trunks are hollow inside so that the central, older wood is missing... In the end, only three from a total of eight olive trees could be successfully dated. The dated ancient olive trees do not, however, allow any hypothesis to be made with regard to the age of the remaining five giant olive trees."^[211] Babcox concludes, "The roots of the eight oldest trees are possibly much older. Visiting guides to the garden often state that they are two thousand years old."^[212]
• The 2,000-year-old^[213] Bidni olive trees on Malta, which have been confirmed through carbon dating,^[214] have been protected since 1933^[215] and are listed in UNESCO's Database of National Cultural Heritage Laws.^[216] In 2011, after recognising their historical and landscape value, and in recognition of the fact that "only 20 trees remain from 40 at the beginning of the 20th century",^[217] Maltese authorities declared the ancient Bidni olive grove at Bidnija as a Tree Protected Area.^[218]

• Examples of olive trees
• 
  Kaštela, Croatia
• 
  Canneto Sabino, Italy
• 
  Karystos, Euboia, Greece
• 
  Partenit, Ukraine

Olives are one of the most extensively cultivated fruit crops in the world.^[219] As of 2024, olive groves occupied roughly 11.6 million hectares (28.6 million acres), comprising one-quarter of the world's permanent cultivated area.^[220] By comparison, in 2011, about 9.6 million hectares (24 million acres) were planted with olive trees, which was more than twice the amount of land devoted to apples, bananas, or mangoes; only coconut trees and oil palms commanded more space.^[221] Cultivation area tripled from 2.6 to 7.95 million hectares (6.4 to 19.6 million acres) between 1960 and 1998 and reached a peak of 10 million hectares (25 million acres) in 2008. Nevertheless, live production in the Mediterranean region has declined since 2019 due to climate, economic and political factors.

According to the Food and Agriculture Organization, the 10 leading producers are all in the Mediterranean region and responsible for 95% of the world's olives.^[222] Spain is the world's leading producer and concentrates the largest land area to olive cultivation, with more than 180 million trees spanning over 2,507,684 hectares, followed by Tunisia (1,746,360 ha) and Italy (1,143,363 ha).^[220] In Italy, olive tree cultivation is widespread in the south, accounting for three quarters of its production; it is less abundant in the colder north of Italy, although growth has increased, particularly in the more temperate microclimates of Liguria and the hills around Lake Garda. Approximately 170 million plants are distributed over one million farms.^[223]

In terms of olive oil output, Spain is by far the largest producer, making up 25% of the global supply, followed by Italy, Morocco, and Tunisia.^[224] The European Union is responsible for nearly 60% of the world's olive oil.^[220]

Main countries of production (as of 2016 per FAOSTAT)^[225]

Country/Region	Production (tonnes)	Cultivated area (hectares)	Yield (tonnes/ha)
World	19,267,000	10,650,000	1.8091
European Union	11,686,528	5,028,637	2.3240
Spain	6,560,000	2,573,000	2.5490
Greece	2,343,000	887,000	2.6414
Italy	2,092,000	1,165,000	1.7950
Turkey	1,730,000	846,000	2.0460
Morocco	1,416,000	1,008,000	1.4044
Syria	899,000	765,000	1.1748
Tunisia	700,000	1,646,000	0.4253
Algeria	697,000	424,000	1.6437
Egypt	694,000	67,000	6.7293
Portugal	617,000	355,000	1.7394

Olives, green

Marinated green olives
Nutritional value per 100 g (3.5 oz)
Energy	609 kJ (146 kcal)
Carbohydrates	3.84 g
Sugars	0.54 g
Dietary fiber	3.3 g
Fat	15.32 g
Saturated	2.029 g
Monounsaturated	11.314 g
Polyunsaturated	1.307 g
Protein	1.03 g
Vitamins and minerals Vitamins Quantity %DV† Vitamin A equiv. beta-Carotene lutein zeaxanthin 2% 20 μg 2% 231 μg 510 μg Thiamine (B1) 2% 0.021 mg Riboflavin (B2) 1% 0.007 mg Niacin (B3) 1% 0.237 mg Vitamin B6 2% 0.031 mg Folate (B9) 1% 3 μg Choline 3% 14.2 mg Vitamin E 25% 3.81 mg Vitamin K 1% 1.4 μg Minerals Quantity %DV† Calcium 4% 52 mg Iron 3% 0.49 mg Magnesium 3% 11 mg Phosphorus 0% 4 mg Potassium 1% 42 mg Sodium 68% 1556 mg
Other constituents	Quantity
Water	75.3 g
Full Link to USDA Database entry
†Percentages estimated using US recommendations for adults,[226] except for potassium, which is estimated based on expert recommendation from the National Academies.[227]

One hundred grams of cured green olives provide 146 calories, are a rich source of vitamin E (25% of the Daily Value, DV), and contain a large amount of sodium (104% DV); other nutrients are insignificant. Green olives are 75% water, 15% fat, 4% carbohydrates and 1% protein (table).

The polyphenol composition of olive fruits varies during fruit ripening and during processing by fermentation when olives are immersed whole in brine or crushed to produce oil.^[228] In raw fruit, total polyphenol contents, as measured by the Folin method, are 117 mg/100 g in black olives and 161 mg/100 g in green olives, compared to 55 and 21 mg/100 g for extra virgin and virgin olive oil, respectively.^[228] Olive fruit contains several types of polyphenols, mainly tyrosols, phenolic acids, flavonols and flavones, and for black olives, anthocyanins. The main bitter flavor of olives before curing results from oleuropein and its aglycone which total in content, respectively, 72 and 82 mg/100 g in black olives, and 56 and 59 mg/100 g in green olives.^[228]

During the crushing, kneading and extraction of olive fruit to obtain olive oil, oleuropein, demethyloleuropein and ligstroside are hydrolyzed by endogenous beta-glucosidases^[229] to form aldehydes, dialdehydes, and aldehydic aglycones.^[230] Polyphenol content also varies with olive cultivar and the manner of presentation, with plain olives having higher contents than those that are pitted or stuffed.^[230][231]

Olive tree pollen is extremely allergenic, with an OPALS allergy scale rating of 10 out of 10.^[232] Olea europaea is primarily wind-pollinated^[233] and its buoyant pollen is a strong trigger for asthma.^[232] One popular variety, 'Swan Hill', is widely sold as an "allergy-free" olive tree; however, this variety does bloom and produce allergenic pollen.^[232]

• List of olive cultivars
• Moria (tree)
• Olive skin