Everyone thinks they know about citrus fruits. We squeeze lemons over fish, drink orange juice at breakfast and zest limes into cocktails. But the oranges, lemons and grapefruit we know so well are relatively recent arrivals in most of the world, and most of them are hybrids with a surprisingly complicated family tree.
Where citrus comes from
A large genetic study published in the journal Nature in 2018 traced the origin of citrus to the southeastern foothills of the Himalayas, in an area that today includes parts of northeastern India, northern Myanmar and the Chinese province of Yunnan. From there, wild citrus species spread across South and East Asia, Southeast Asia and as far as Australia over millions of years.
A handful of ancestral species gave rise to almost all the citrus we eat:
- Citron (Citrus medica), a large, fragrant fruit with a thick rind and little juice.
- Pomelo (Citrus maxima), the largest citrus fruit.
- Mandarin (Citrus reticulata), small, sweet and easy to peel.
- Papedas, a group of mostly sour, often thorny wild citrus. One of them is a parent of the Key lime.
Crosses between these species, often repeated over centuries, produced the familiar fruits. The sweet orange and the sour (bitter) orange are both mandarin-pomelo hybrids. The lemon is a cross between sour orange and citron. The grapefruit is younger still: it arose in Barbados in the 18th century as a chance cross between sweet orange and pomelo.
Chinese growers were cultivating and selecting citrus very early. In 1178, Han Yanzhi wrote the Ju Lu, a monograph on the oranges of Wenzhou, describing 27 varieties of sweet, sour and mandarin oranges as well as citrons, kumquats and the trifoliate orange, along with nursery methods, grove management and diseases. It is one of the oldest known works devoted to a single fruit.
The citron reaches the Mediterranean
The citron was the first citrus fruit to reach the Mediterranean. It traveled west through Persia, and archaeologists have found citron pollen in a royal Persian-period garden near Jerusalem dating to around the 5th century BCE. Around 300 BCE, the Greek botanist Theophrastus described the "Median" or "Persian apple," a fruit that was not eaten but was prized for its fragrance and used to keep moths away from clothes.
The lemon arrived later, probably in the first centuries BCE and CE. In ancient Rome, citrons and lemons were rare luxuries. Lemons appear in wall paintings and mosaics, and remains have been found at Pompeii, but they seem to have been status symbols for wealthy households rather than everyday foods.
The etrog: the citrus of the Feast of Tabernacles
The Bible doesn't mention citrus by name, but it plays a central role in Jewish tradition. Leviticus 23:40 instructs worshippers to take "the fruit of goodly trees" (pri etz hadar), along with palm branches, myrtle and willow, during the Feast of Tabernacles (Sukkot). Jewish tradition identifies that fruit as the etrog, a variety of citron. Some historians think Jews became familiar with the citron during the Babylonian exile and the Persian period that followed.
The etrog is still one of the four species used at Sukkot today. A good etrog should be as unblemished and well formed as possible, so growers protect the fruit carefully from scratches by leaves and thorns. Etrogs are grown in Israel, Italy, Morocco and elsewhere and shipped to Jewish communities around the world.
Citrons come in many forms. Some are smooth, some ribbed and knobbly, and one variety, Buddha's hand, divides into long, finger-like segments. Their flesh is dry and sour, with little juice; the main part of the fruit is its thick white rind. Today citron is used mainly for its fragrant zest and for candied peel, a classic ingredient in Italian panettone and many fruitcakes.
Citrus in the medieval Islamic world and Europe
The great spread of citrus came with the expansion of the Islamic world from the 7th century onward. Arab traders, farmers and botanists brought the sour orange, lemon, lime and pomelo west through Persia, Iraq, Syria and Egypt, and on to North Africa, Sicily and Spain by around the 10th century. Courtyards and gardens planted with sour oranges, such as the Patio de los Naranjos of the Great Mosque of Córdoba and the gardens of Seville, are a legacy of this period.
Arab cooks valued sour flavors, using citron, sour orange and lemon juice alongside vinegar, sour pomegranate and verjuice. These tastes passed into the cooking of Christian Europe. Medieval Latin recipe collections such as the Liber de Coquina include a dish called limonia, chicken cooked with lemon juice. The Catalan Libre del Coch, printed in 1520, uses orange and lemon juice in sauces and stews, and candied lemon peel, a technique from Arab confectionery, remained popular for centuries.
When a medieval European text mentions an "orange," it almost always means the sour orange. It is too bitter to eat raw, but it was used for juice in cooking, for marmalade and candied peel, and for its fragrant blossoms and oil. The sweet orange we eat today reached Europe only in the late 15th and 16th centuries, probably brought from Asia by Portuguese and Genoese traders. In many languages it is still named after Portugal: portokali in Greek, portakal in Turkish and burtuqal in Arabic.
Fresh citrus remained expensive in northern Europe. From the 16th and 17th centuries, wealthy families built orangeries, heated glasshouses where potted orange and lemon trees could survive the winter, and the orangery at Versailles became one of the most famous. Mandarins reached Europe later still, in the 19th century.
Citrus in the Americas
Christopher Columbus carried citrus seeds to the Caribbean on his second voyage in 1493, and Spanish and Portuguese settlers planted oranges, lemons and limes throughout their American colonies. Spanish settlers grew citrus in Florida by the 16th century, and Spanish missionaries planted it in California in the 18th century. Large commercial industries developed in both states in the 19th century. The navel orange that made California famous came from a seedless variety from Bahia, Brazil; three trees were planted in Riverside in 1873, and one of them is still alive. Read more about growing your own in a citrus garden.
Citrus and scurvy
On long sea voyages, sailors who went months without fresh fruit and vegetables developed scurvy, a disease now known to be caused by a lack of vitamin C. In 1747, the Scottish naval surgeon James Lind ran one of the first controlled clinical trials, giving sailors with scurvy different treatments; those given oranges and lemons recovered fastest. The British Royal Navy began issuing lemon juice to its sailors in the 1790s, later switching to lime juice from its Caribbean colonies, which is how British sailors earned the nickname "limeys."
Citrus today
Citrus is now one of the world's most widely grown fruit crops. Brazil and the United States are major producers of orange juice, China grows more citrus overall than any other country, and Spain is one of the world's biggest exporters of fresh oranges and mandarins. Plant breeders continue to develop new varieties, from seedless mandarins to blood oranges with deeper color, and older types such as yuzu, finger limes and bergamot have found new fans among cooks and bartenders. Find out more about the many kinds of citrus fruits.
Sources
- Genomics of the origin and evolution of Citrus (Wu et al., Nature, 2018)
- The citrus route revealed: from Southeast Asia into the Mediterranean (Langgut, HortScience, 2017)
Last reviewed November 2026.
