Mandarin orange

Citrus reticulata is from Latin, where reticulata means "netted".[6] The name mandarin orange is a calque of Swedish mandarin apelsin [apelsin from German Apfelsine (Apfel + Sina) meaning Chinese apple], first attested in the 18th century. The form "mandarine" derives from the French name for this fruit. The reason for the epithet "mandarin" is not clear; it may relate to the yellow colour of some robes worn by mandarin dignitaries.[7][8]

Mandarin oranges growing on a tree in Crete.

Citrus reticulata is a moderate-sized tree some 7.6 metres (25 ft) in height.[1][6] The tree trunk and major branches have thorns.[1] The leaves are shiny and green, rather small.[1] The petioles are short, almost wingless or slightly winged.[1] The flowers are borne singly or in small groups in the leaf-axils.[1] Citrus are usually self-fertile (needing only a bee to move pollen within the same flower) or parthenocarpic (not needing pollination and therefore seedless, such as the satsuma). A mature mandarin tree can yield up to 79 kilograms (175 lb) of fruit.[9]

Mandarin oranges in a mesh bag

Mandarin orange fruits are small 40–80 millimetres (1.6–3.1 in).[1] Their colour is orange, orange-yellow, or orange-red.[2] The skin is thin and peels off easily.[1] Their easiness to peel is an important advantage of mandarin oranges over other citrus fruits.[2] Just like with other citrus fruits, the endocarp (inner flesh) is separated into segments, which in their turn consist of a large number of elongated cells.[1] The fruits may be seedless or contain a small number of seeds. Mandarin orange fruits are sweet to taste, and can be eaten as whole or squeezed to make juice.[1][2]

Tangerines, mandarins, clementines, satsumas Production, 2017 (millions of tonnes)
China	18.0
Spain	2.0
Turkey	1.6
Morocco	1.3
Brazil	1.0
Egypt	1.0
World total	33.4
Source: UN Food and Agriculture Organization

In 2017, world production of mandarin oranges (combined with tangerines, clementines, and satsumas in reporting to FAOSTAT) was 33.4 million tonnes, led by China with 54% of the global total (table).[10] Producing more than one million tonnes each in 2017 were Spain, Turkey, Morocco, Brazil, and Egypt.[10]

A mandarin orange contains 85% water, 13% carbohydrates, and negligible amounts of fat and protein (table). Among micronutrients, only vitamin C is in significant content (32% of the Daily Value) in a 100-gram reference serving, with all other nutrients in low amounts.

Mandarin fruitlets

During Chinese New Year, mandarin oranges/tangerine/satsumas are considered traditional symbols of abundance and good fortune. During the two-week celebration, they are frequently displayed as decoration and presented as gifts to friends, relatives, and business associates. Mandarin oranges, particularly from Japan, are a Christmas tradition in Canada, the United States and Russia.

In Canada and the United States, they are commonly purchased in 5- or 10-pound boxes,[2] individually wrapped in soft green paper, and given in Christmas stockings. This custom goes back to the 1880s, when Japanese immigrants in the United States began receiving Japanese mandarin oranges from their families back home as gifts for the New Year. The tradition quickly spread among the non-Japanese population, and eastwards across the country: each November harvest, "The oranges were quickly unloaded and then shipped east by rail. 'Orange Trains' – trains with boxcars painted orange – alerted everyone along the way that the irresistible oranges from Japan were back again for the holidays. For many, the arrival of Japanese mandarin oranges signaled the real beginning of the holiday season."[12] This Japanese tradition merged with European traditions related to the Christmas stocking. Saint Nicholas is said to have put gold coins into the stockings of three poor girls so that they would be able to afford to get married.[13] Sometimes the story is told with gold balls instead of bags of gold, and oranges became a symbolic stand-in for these gold balls, and are put in Christmas stockings in Canada[13][14] along with chocolate coins wrapped in gold foil.

Satsumas were also grown in the United States from the early 1900s, but Japan remained a major supplier.[15] U.S. imports of these Japanese oranges was suspended due to hostilities with Japan during World War II.[12] While they were one of the first Japanese goods allowed for export after the end of the war, residual hostility led to the rebranding of these oranges as "mandarin" oranges.[12]

The delivery of the first batch of mandarin oranges from Japan in the port of Vancouver, British Columbia (Canada), is greeted with a festival that combines Santa Claus and Japanese dancers[14]—young girls dressed in traditional kimonos.[16]

Historically, the Christmas fruit sold in North America was mostly Dancys, but now it is more often a hybrid.[17]

Mandarins are one of the core ancestral citrus taxa, and are thought to have evolved in regions including South China and Japan in East Asia, and Vietnam in Southeast Asia.[18][5] Mandarins appear to have been domesticated at least twice, in the north and south Nanling Mountains. Wild mandarins are still found there, including Daoxian mandarines (sometimes given the species name Citrus daoxianensis) as well as some members of the group traditionally called 'Mangshan wild mandarins', a generic grouping for the wild mandarin-like fruit of the Mangshan area that includes both true mandarins and the genetically-distinct and only distantly-related Mangshanyegan. The wild mandarins were found to be free of the introgressed pomelo (C. maxima) DNA found in domestic mandarins but they did appear to have small amounts (~1.8%) of introgression from the ichang papeda, which grows wild in the same region.[19]

The Nanling Mountains are also home to northern and southern genetic clusters of domestic mandarins that have similar levels of sugars in the fruit compared to their wild relatives, but appreciably (in some almost 90-fold) lower levels of citric acid. The clusters display different patterns of pomelo introgression, have different deduced historical population histories, and are most closely related to distinct wild mandarins, suggesting two independent domestications in the north and south.[19] All tested domesticated cultivars were found to belong to one of these two genetic clusters, with varieties such as Nanfengmiju, Kishu and Satsuma deriving from the northern domestication event producing larger, redder fruit, while Willowleaf, Dancy, Sunki, Cleopatra, King, Ponkan, and others derived from the smaller, yellower-fruited southern cluster.[19]

The Tanaka classification system divided domestic mandarins and similar fruit into numerous species, giving distinct names to cultivars such as willowleaf mandarins (C. deliciosa), satsumas (C. unshiu), tangerines (C. tangerina). Under the Swingle system, all these are considered to be varieties of a single species, Citrus reticulata.[20] Hodgson represented them as several subgroups: common (C. reticulata), Satsuma, King (C. nobilis), Mediterranean (willowleaf), small-fruited (C. indica, C. tachibana and C. reshni), and mandarin hybrids.[21]

Genetic analysis is consistent with mandarins representing a single species, with much of the variation within mandarins being due to hybridization.[4] There are only a small number of genetically-pure cultivars, including the Tachibana orange, which Talon determined to be sufficiently divergent to be classified as a distinct subspecies,Citrus reticulata tachibana[4] and found by Wang to have branched from the wild mandarin lineage prior to the split that gave rise to the two domesticated clusters. Others, such as Sun Chu Sha mandarin[18][4] and Nanfengmiju,[22] were found to be pure in initial genomic characterization, but Wang detected in them not only an apparent Ichang papeda introgression found in all examined mandarins but also the distinct pomelo DNA of the domesticated mandarins.[19] Following initial hybridization, cultivars were produced by backcrossing the initial mandarin-pomelo hybrids to produce mandarins with limited pomelo contribution,[4] that differed between the northern and southern domesticates.[19] An 'acidic' group of cultivars including Sunki and Cleopatra mandarins that likewise previously were thought to be pure but since found to contain small regions of introgressed pomelo DNA are too sour to be edible, but are widely used as rootstock and grown for juice.[20][4] Another group of mandarins, including some tangerines, Satsuma and King mandarins, show a greater pomelo contribution and derive from the limited-pomelo hybrids being crossed again, with sweet orange or pomelo, and likewise backcrossing in some cases, producing cultivars with moderate to high levels of pomelo introgression.[4] Hybrid mandarins thus fall on a continuum of increasing pomelo contribution with clementines, sweet and sour oranges, and grapefruit.[18] Mandarins and their hybrids are sold under a variety of names. In the genomic-based species taxonomy of Ollitrault et al., only pure mandarins would fall under C. reticulata, while the pomelo admixture found in the majority would cause them to be classified as varieties of C. aurantium.[23]

• Orange (fruit)

Wikimedia Commons has media related to Citrus reticulata.

Data related to Citrus reticulata at Wikispecies