Regularity: Regularly occurring
Solitary or in axillary fasicles; white. Flowering from March-April.
An oblong or globose berry, fleshy; seeds many. Fruiting throughout the year.
Petiole often winged. Branchlets armed with spines. Leaves gland dotted.
Habitat & Distribution
Molecular Biology and Genetics
Barcode data: Citrus medica
Statistics of barcoding coverage: Citrus medica
Public Records: 6
Specimens with Barcodes: 9
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: NNA - Not Applicable
Relevance to Humans and Ecosystems
Stem: Used in febrifuge pills in French Guiana. Fruit: Used for malaria and to treat coughs and colds in NW Guyana.
The fruits are pickled.
Leaves are externally used to relieve pain and inflamation. It is also used to treat skin disorders and itching.
The citron is a large fragrant citrus fruit with a thick rind, botanically classified as Citrus medica by both the Swingle and Tanaka botanical name systems. It is one of the four original citrus fruits (the others being pommelo, mandarine and papeda), from which most other citrus types developed through natural hybrid speciation or artificial hybridization.
The fruit's English name "citron" derives ultimately from Latin, citrus, which is also the origin of the genus name.
A source of confusion is that citron or similar words in French, Hungarian, Finnish, Latvian, the West Slavic languages, and all Germanic languages but English are false friends, as they refer to the lemon. Indeed, into the 16th century, the English name citron included the lemon and perhaps the lime as well.
In most Arabic languages it is called Turunj, or similar, but in Syria and many other Muslim countries it is called Kabbad; in Japanese it is called Bushkan (maybe referring only to the fingered varieties).
While the lemon or orange are peeled to consume their pulpy and juicy segments, the citron's pulp is dry, containing a small quantity of insipid juice, if any. The main content of a citron fruit is the thick white rind, which adheres to the segments and cannot be separated from them easily. The citron gets halved and depulped, then its rind is cooked in sugar, diced, and used as a confection.
Today the citron is used for the fragrance or zest of its flavedo, but the most important part is still the inner rind (known as pith or albedo), which is a fairly important article in international trade and is widely employed in the food industry as succade, as it is known when it is candied in sugar.
In Iran, the citron's thick white rind is used to make jam; in Pakistan the fruit is used to make jam but is also pickled; in South Indian cuisine, the citron is widely used in pickles and preserves. In Korea, citron (called yujacha) is used to make tea, which supposedly helps to suppress coughing, relieve hangovers, and is effective in curing indigestion.
From ancient through medieval times, the citron was used mainly for medical purposes: to combat seasickness, pulmonary troubles, intestinal ailments, scurvy and other disorders. The essential oil of the flavedo (the outermost, pigmented layer of rind) was also regarded as an antibiotic. Citron juice with wine was considered an effective antidote to poison, as Theophrastus reported. In the Ayurvedic system of medicine, the juice is still used for treating conditions like nausea, vomiting, and excessive thirst.
The juice of the citron has a high Vitamin C content and used medicinally as an anthelminthic, appetizer, tonic, in cough, rheumatism, vomiting, flatulence, haemorrhoids, skin diseases and weak eyesight. A recent study has shown that citron has some cardiovascular benefits.
There is an increasing market for the citron for the soluble fiber (pectin) found in its thick albedo. There are also scientific claims that modified citrus pectin can help even against cancer.
The citron is also used by Jews (the word for it in Hebrew is etrog) for a religious ritual during the Feast of Tabernacles; therefore, is considered to be a Jewish symbol which is found on various Hebrew antiques and archaeological findings. Citrons used for ritual purposes cannot be grown by grafting branches.
Description and variation
The citron fruit is usually ovate or oblong, narrowing towards the stylar end. However, the citron's fruit shape is highly variable, due to the large quantity of albedo, which forms independently according to the fruits' position on the tree, twig orientation, and many other factors. The rind is leathery, furrowed, and adherent. The inner portion is thick, white and hard; the outer is uniformly thin and very fragrant. The pulp is usually acidic, but also can be sweet, and even pulpless varieties are found.
Most citron varieties contain a large number of monoembryonic seeds. They are white, with dark innercoats and red-purplish chalazal spots for the acidic varieties, and colorless for the sweet ones. Some citron varieties are also distinct, having persistent styles, that do not fall off after fecundation. Those are usually promoted for etrog use.
Some citrons have medium-sized oil bubbles at the outer surface, medially distant to each other. Some varieties are ribbed and faintly warted on the outer surface. There is also a fingered citron variety called Buddha's hand.
The color varies from green, when unripe, to a yellow-orange when overripe. The citron does not fall off the tree and can reach 8–10 pounds (4–5 kg) if not picked before fully mature. However, they should be picked before the winter, as the branches might bend or break to the ground, and may cause numerous fungal diseases for the tree.
Citrus medica is a slow-growing shrub or small tree that reaches a height of about 8 to 15 ft (2 to 5 m). It has irregular straggling branches and stiff twigs and long spines at the leaf axils. The evergreen leaves are green and lemon-scented with slightly serrate edges, ovate-lanceolate or ovate elliptic 2.5 to 7.0 inches long. Petioles are usually wingless or with minor wings. The flowers are generally unisexual providing self-pollination, but some male individuals could be found due to pistil abortion. The clustered flowers of the acidic varieties are purplish tinted from outside, but the sweet ones are white-yellowish.
The citron tree is very vigorous with almost no dormancy, blooming several times a year, and is therefore fragile and extremely sensitive to frost.
Varieties and hybrids
The acidic varieties include the Florentine and Diamante citron from Italy, the Greek citron and the Balady citron from Israel. The sweet varieties include the Corsican and Moroccan citrons. Between the pulpless are also some fingered varieties and the Yemenite citron.
There are also a number of citron hybrids; for example, ponderosa lemon, the lumia and rhobs el Arsa are known citron hybrids, some are claiming that even the Florentine citron is not pure citron, but a citron hybrid.
Origin and distribution
Despite the variation among the cultivars, authorities agree the citron is an old and original species. There is molecular evidence that all other cultivated citrus species arose by hybridization among four ancestral types, which are the citron, pomelo, mandarin and some papedas. The citron is believed to be the purest of them all, since it is usually fertilized by self-pollination, and is therefore generally considered to be a male parent of any citrus hybrid rather than a female one.
Today, authorities agree that all citrus species are native to Southeast Asia where they are found wild and in an uncultivated form. The story of how they spread to the Mediterranean has been reported by Francesco Calabrese, Henri Chapot, Samuel Tolkowsky, Elizabetta Nicolisi, and others.
The citron could also be native to India where it borders on Burma, in valleys at the foot of the Himalayas, and in the Indian Western Ghats. It is thought that by the time of Theophrastus, the citron was mostly cultivated in the Persian Gulf on its way to the Mediterranean basin, where it was cultivated during the later centuries in different areas as described by Erich Isaac. Many mention the role of Alexander the Great and his armies as they attacked Persia and what is today Pakistan, as being responsible for the spread of the citron westward, reaching the European countries such as Macedonia and Italy.
The citron is mentioned in the Torah as being required for ritual use during the Feast of Tabernacles (Lev. 23:40). According to this tradition, the Jews brought it back to Israel from their exile in Egypt, where the Egyptologist and archaeologist Victor Loret claimed to have identified it depicted on the walls of the botanical garden at the Karnak Temple, which dates back to the time of Thutmosis III, approximately 3,000 years ago.
In the east and south there are special plants... i.e. in Media and Persia there are many types of fruit, between them there is a fruit called Median or Persian Apple. The tree has a leaf similar to and almost identical with that of the andrachn (Arbutus andrachne L.), but has thorns like those of the apios (the wild pear, Pyrus amygdaliformis Vill.) or the firethorn, Cotoneaster pyracantha Spach.), except that they are white, smooth, sharp and strong.
The fruit is not eaten, but is very fragrant, as is also the leaf of the tree; and the fruit is put among clothes, it keeps them from being moth-eaten. It is also useful when one has drunk deadly poison, for when it is administered in wine; it upsets the stomach and brings up the poison. It is also useful to improve the breath, for if one boils the inner part of the fruit in a dish or squeezes it into the mouth in some other medium, it makes the breath more pleasant.
The seed is removed from the fruit and sown in the spring in carefully tilled beds, and it is watered every fourth or fifth day. As soon the plant is strong it is transplanted, also in the spring, to a soft, well watered site, where the soil is not very fine, for it prefers such places.
And it bears its fruit at all seasons, for when some have gathered, the flower of the others is on the tree and is ripening others. Of the flowers I have said those that have a sort of distaff [meaning the pistil] projecting from the middle are fertile, while those that do not have this are sterile. It is also sown, like date palms, in pots punctured with holes.This tree, as has been remarked, grows in Media and Persia.
Pliny the Elder
There is another tree also with the same name of "citrus," and bears a fruit that is held by some persons in particular dislike for its smell and remarkable bitterness; while, on the other hand, there are some who esteem it very highly. This tree is used as an ornament to houses; it requires, however, no further description.
The citron tree, called the Assyrian, and by some the Median apple, is an antidote against poisons. The leaf is similar to that of the arbute, except that it has small prickles running across it. As to the fruit, it is never eaten, but it is remarkable for its extremely powerful smell, which is the case, also, with the leaves; indeed, the odour is so strong, that it will penetrate clothes, when they are once impregnated with it, and hence it is very useful in repelling the attacks of noxious insects.
The tree bears fruit at all seasons of the year; while some is falling off, other fruit is ripening, and other, again, just bursting into birth. Various nations have attempted to naturalize this tree among them, for the sake of its medical properties, by planting it in pots of clay, with holes drilled in them, for the purpose of introducing the air to the roots; and I would here remark, once for all, that it is as well to remember that the best plan is to pack all slips of trees that have to be carried to any distance, as close together as they can possibly be placed.
It has been found, however, that this tree will grow nowhere except in Media or Persia. It is this fruit, the pips of which, as we have already mentioned, the Parthian grandees employ in seasoning their ragouts, as being peculiarly conducive to the sweetening of the breath. We find no other tree very highly commended that is produced in Media.Citrons, either the pulp of them or the pips, are taken in wine as an antidote to poisons. A decoction of citrons, or the juice extracted from them, is used as a gargle to impart sweetness to the breath. The pips of this fruit are recommended for pregnant women to chew when affected with qualmishness. Citrons are good, also, for a weak stomach, but it is not easy to eat them except with vinegar.
- Klein, J. (2014). "Citron Cultivation, Production and Uses in the Mediterranean Region". In Z. Yaniv; N. Dudai. Medicinal and Aromatic Plants of the Middle-East 2. Springer Netherlands. pp. 199–214. doi:10.1007/978-94-017-9276-9_10.
- Citron at the Oxford English dictionary 
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- Preparation and Characterization of Pectin...
- "Researchers demonstrate how modified citrus pectin works against cancer". News-Medical.net. 4 June 2013.
- See Etrog
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- The Search for the Authentic Citron: Historic and Genetic Analysis; HortScienc 40(7):1963–1968. 2005
- Chromosome Numbers in the Subfamily Aurantioideae with Special Reference to the Genus Citrus; C. A. Krug. Botanical Gazette, Vol. 104, No. 4 (Jun., 1943), pp. 602–611
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- Calabrese, La favolosa storia degli agrumi. L'EPOS, 1998, Palerno Italy. English translation in Citrus: the genus citrus
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- "The Garden - Sir Joseph Hooker. Flora of British India, i. 514". google.com.
- COUNTRY REPORT TO THE FAO INTERNATIONAL TECHNICAL CONFERENCE ON PLANT GENETIC RESOURCES (Leipzig, 1996); Prepared by: Nepal Agricultural Research Council; Kathmandu, June 1995; CHAPTER 2.2
- Isaac, "The Citron in the Mediterranean: a study in religious influences", Economic Geography, Vol. 35 No. 1. (Jan. 1959) pp. 71–78
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- Historia plantarum 4.4.2-3 (exc. Athenaeus Deipnosophistae 3.83.d-f); cf. Vergil Georgics 2.126-135; Pliny Naturalis historia 12.15,16.
- Historia plantarum 1.13.4.
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The Bizzaria of Florence (citrus medica + citrus aurantium), which is probably the first graft chimera obtained, is a graft between the Florentine citron and sour orange. It produces branches of regular Florentine citron including such leaves, and from the other side branches of sour orange. The most interesting part of it is the middle shoot, which mixes characteristics of both. The fruit contains characteristics of both citron and orange.
This is not like a regular somatic hybrid which is due to plant sexuality; its offspring is intermediate showing influences of both parents. But the Florentine Bizzaria, named after its origin, shows an unusual fruit which has both characteristics distinctly expressed in close proximity.
The Bizzaria was discovered in 1640 by Pietro Nati at the Villa named Torre degli Agli, which belonged to the wealthy Panciatichi banking family. The Bizzaria was thought to be lost when it was rediscovered in year 1970s by Paolo Galleotti, the head gardener of the Villa di Castello and of The Boboli Gardens in Florence.
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French Guiana: citronnier. Guyana: citron.
The Buddha-hand Citron (佛手 fo shou), with separated segments ± surrounded by pericarp, is best treated as a cultivar, correctly Citrus medica ‘Fingered.’
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