Pompia (''Citrus medica tuberosa''), also called pumpia, sa pompia, spompia, and China citron, is a ''

Citrus ''Citrus'' is a genus of flowering plant, flowering trees and shrubs in the rue family, Rutaceae. Plants in the genus produce citrus fruits, including important crops such as Orange (fruit), oranges, Lemon, lemons, grapefruits, pomelos, and lim ...

hybrid Hybrid may refer to: Science * Hybrid (biology), an offspring resulting from cross-breeding ** Hybrid grape, grape varieties produced by cross-breeding two ''Vitis'' species ** Hybridity, the property of a hybrid plant which is a union of two dif ...

cultivated for its edible

fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...

Distribution

Pompia originated and is found only in

Sardinia Sardinia ( ; it, Sardegna, label=Italian, Corsican and Tabarchino ; sc, Sardigna , sdc, Sardhigna; french: Sardaigne; sdn, Saldigna; ca, Sardenya, label=Algherese and Catalan) is the second-largest island in the Mediterranean Sea, after ...

, especially the eastern half, where it can be found growing wild in

citrus ''Citrus'' is a genus of flowering plant, flowering trees and shrubs in the rue family, Rutaceae. Plants in the genus produce citrus fruits, including important crops such as Orange (fruit), oranges, Lemon, lemons, grapefruits, pomelos, and lim ...

groves and cultivated in backyards or orchards. The earliest descriptions of it date back to 1780 and it likely originated around 1760 in

Milis Milis, Miris or Milis in sardinian language, is a '' comune'' (municipality) in the Province of Oristano in the Italian region Sardinia, located about northwest of Cagliari and about north of Oristano. As of 31 December 2004, it had a populati ...

Description

The

is moderately large (at least as large as a

grapefruit The grapefruit (''Citrus'' × ''paradisi'') is a subtropical citrus tree known for its relatively large, sour to semi-sweet, somewhat bitter fruit. The interior flesh is segmented and varies in color from pale yellow to dark pink. Grapefruit is ...

), round and sometimes oblate or square in shape, and has a rough, warty, yellow (green when unripe), thick, and sometimes ribbed rind. It sometimes has a circular depression in the top or bottom. The inner pulp is acidic, yellow, and mostly dry and is generally considered inedible; it has been described as bitter and chewy. It has a subtle fragrance and contains 13-14 wedges with large vesicles. It is usually seedless but may contain 1-3

polyembryonic Polyembryony is the phenomenon of two or more embryos developing from a single fertilized egg. Due to the embryos resulting from the same egg, the embryos are identical to one another, but are genetically diverse from the parents. The genetic differ ...

seeds which measure 8-12 millimeters in length and are roughly triangular in shape. It weighs up to 1.5 pounds (0.7 kilograms). The tree is densely branched and grows 2–3 meters in height and has an expanded and erect posture. The petiole is unwinged and measures 6-10 millimeters in length. The leaves are elliptical in shape and are dark green in color; they are leathery and the apex is rounded in an ovate to lanceolate shape. The margin is entire and the midrib is very defined. The flowers are white in color and are either solitary or in clusters of 2-8; they usually have five petals. They have numerous stamens and dorsifixed anthers, and the stigma is round and green in color and irregularly lobed. The tree fruits from October to February–March.

Uses

The fruit has been grown and cultivated for at least two centuries in

; however, it did not gain international popularity until the 1990s, when a large orchard of pompia trees were planted as part of a social farming project. Since then, it has become a preside of

Slow Food Slow Food is an organization that promotes local food and traditional cooking. It was founded by Carlo Petrini in Italy in 1986 and has since spread worldwide. Promoted as an alternative to fast food, it strives to preserve traditional and regi ...

. It is most notably used in ''Sa pompia Intrea'', a traditional dessert of

Siniscola Siniscola (; sc, Thiniscòle ) is a ''comune'' (municipality) in the province of Nuoro in the Italian region Sardinia, located about northeast of Cagliari and about northeast of Nuoro. Siniscola borders the following municipalities: Irgoli, L ...

in which the rind of the fruit is candied and then covered with honey and served on an orange leaf. It is also used in various

liquors Liquor (or a spirit) is an alcoholic drink produced by distillation of grains, fruits, vegetables, or sugar, that have already gone through alcoholic fermentation. Other terms for liquor include: spirit drink, distilled beverage or hard ...

and is sometimes grafted onto

sour orange Bitter orange, Seville orange, bigarade orange, or marmalade orange is the citrus tree ''Citrus'' × ''aurantium'' and its fruit. It is native to Southeast Asia and has been spread by humans to many parts of the world. It is probably a cross bet ...

Genetics

Before the parentage was confirmed, the pompia was thought to be a hybrid of a

citron The citron (''Citrus medica''), historically cedrate, is a large fragrant citrus fruit with a thick rind. It is said to resemble a 'huge, rough lemon'. It is one of the original citrus fruits from which all other citrus types developed throu ...

and

lemon The lemon (''Citrus limon'') is a species of small evergreen trees in the flowering plant family Rutaceae, native to Asia, primarily Northeast India (Assam), Northern Myanmar or China. The tree's ellipsoidal yellow fruit is used for culin ...

; however, recent studies have proven the pompia to be a hybrid of the

(''C. medica'') and the

(''C. aurantium''), with the

being the pollen parent and the

being the seed parent. The variety of the

parent has not been confirmed, but it is likely a

Diamante citron The Diamante citron (''Citrus medica'' var. ''vulgaris'' or cv. ''diamante'' − it, cedro di diamante, he, אתרוג קלבריה or גינובה) is a variety of citron named after the town of Diamante, located in the province of Cosenza, Cal ...

or a common poncire. The pompia is genetically synonymous with the

Rhobs el Arsa Rhobs al-Arsa (''Citrus limon'' (L.) Burm. f.) is a very popular citrus fruit in Morocco. Names Rhobs al-Arsa is Arabic for bread of the garden, or ''"Garden Loaf"''. This citrus hybrid has many other names, such as Al-zanbu, Khoubs al-Arsa, Ko ...

and Poncire de Collioure citrons. The

essential oil An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the o ...

composition in the leaf is closer to that of a

, while the EO composition in the zest is closer to that of a

. The major compound in the fruit is

limonene Limonene is a colorless liquid aliphatic hydrocarbon classified as a cyclic monoterpene, and is the major component in the oil of citrus fruit peels. The -isomer, occurring more commonly in nature as the fragrance of oranges, is a flavoring ag ...

at 94%, and it contains smaller amounts of

sesquiterpenes Sesquiterpenes are a class of terpenes that consist of three isoprene units and often have the molecular formula C15H24. Like monoterpenes, sesquiterpenes may be cyclic or contain rings, including many unique combinations. Biochemical modificatio ...

and its derivatives. The rind of the fruit contains

antioxidant Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. This can lead to polymerization and other chain reactions. They are frequently added to industrial products, such as fuels and lubricant ...

substances and the leaves contain

antimicrobial An antimicrobial is an agent that kills microorganisms or stops their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria, and antifungals ar ...

substances that kill ''

Listeria ''Listeria'' is a genus of bacteria that acts as an intracellular parasite in mammals. Until 1992, 17 species were known, each containing two subspecies. By 2020, 21 species had been identified. The genus is named in honour of the British pi ...

'' bacteria on foods.

Taxonomy

''Citrus limon'' var. ''pompia'' is treated as a synonym of ''

Citrus limon The lemon (''Citrus limon'') is a species of small evergreen trees in the flowering plant family Rutaceae, native to Asia, primarily Northeast India (Assam), Northern Myanmar or China. The tree's ellipsoidal yellow fruit is used for culin ...

'' in taxonomy.

References