The Mandarin (Citrus reticulata Blanco) is now, after genetic research and the establishment of molecular markers, considered the third of the three true species in the genus Citrus. The Mandarin with its hybrids and relatives together form the largest group in the genus Citrus. The number of commercially important mandarin varieties almost equals the number of all other horticultural Citrus types combined. Over 450 mandarin types are known today and the estimated number of commercially grown mandarin varieties in the world is more than 300.
Because of the genetic diversity and the many sub-varieties, the classification of Mandarins is more complicated than that of any other citrus types. ‘Mandarin’ is often used as a group or class name within the Mandarin genus, along with a second class name of ‘Tangerines’, and a third class name of ‘ Satsumas’. Mandarins are also the second most commercially important citrus today. In the last twenty years, consumers’ taste has developed a preference for the easily pealable, seedless, tasty, and nicely-colored qualities of many of the varieties in this group. In addition, certain varieties in this group have been marketed with very expensive, but very effective branding and advertising campaigns that appeal to a particularly important group of consumers-children.
The Origin of the Mandarin
The oldest Chinese reference to Citrus is contained in the book “Tribute of Yu”, which by reference is believed to be between 776 and 600 B.C. In this work, a list of tribute items, which included small mandarins were sent to the mythical Emperor Yu, god of irrigation. Confucius (551-479 B.C.)from his writings knew of two kinds of citrus. The first detailed description of Citrus appears in the poem cycle Chiu Chang composed about 250-300 B.C. In the eighth poem, a youth is praised through an extended comparison with a mandarin tree. In 1,179 A.D., Han Yen-Chih named and described 27 varieties of the orange-mandarin group.
The Mandarin was also cultivated in Japan
According to Chōzaburō Tanaka, (1885- 1976) a Japanese botanist who did extensive research in Citrus classification , the first reference to the orange of Wên-chou in Japanese literature “is perhaps a citation in Isei Teikin Orai, one of the oldest books of family letter writing, composed by Kokwan (1278-1346 A.D.).” This provides evidence that varieties of the mandarin orange reached Japan about the time that the orange and the lemon reached Europe. The exact routes of dispersion are not all clear but Citrus seems to have slowly but surely made its way across wide areas including Europe and Africa.
Genetic studies using morphology and molecular markers to determine the relationships between the Citrus genus now support that the ‘sweet orange’ (the most widely consumed citrus fruit today) as well as the ‘sour orange’ (used for rootstock, marmalades-Seville Orange-, and ornamentals) are derived from the genus Citrus reticulata in combination with the genus Citrus grandis, the pummelo.
THE MANDARIN ORANGES
This list of citrus that is classified under the genus of the Mandarin are far too numerous to detail in even a ‘few’ pages. Below are examples and facts of several of the most popular varieties we often just call Tangerines:
Clementines – Several sub-varieties of the Clementine have been widely grown in the Mediterranean basin including Spain, Morocco, Corsica, Spain, and Algeria and now grown in all commercially viable citrus producing areas of the world. Reportedly the Clementine originated as a chance hybrid in the Algerian Gardens of Father Clement Rodier in 1902. The Clementine was brought to the USA and the research center in Riverside in 1914 as part of a world-wide collection by plant pathologist HS Fawcett. It was written by another academia stalwart of the California citrus industry, RW Hodgson (1893-1966), “Climatically, the distinctive features of the Clementine variety are its low total heat requirements for fruit maturity and the sensitivity of the seedless fruit to infavorable conditions during the flowering and fruit-setting period. In regions of high total heat, the Clementine matures very early -- only slightly later than the satsuma mandarins. Such regions also favor production of fruit of maximum size and best eating quality...With reference to sensitivity of seedless fruits, however, the almost universal experience has been one of uncertain and irregular bearing behavior because of excessive shedding of young fruits during the fruit-setting period and a few weeks thereafter. Moreover, it has been noted that shedding is correlated with the seed content of the fruit...the bearing behavior...can be regularized by cross-pollination.” These characteristics and several marketing efforts have made the Clementine extremely popular world-wide.
Satsumas – Hodgson writes, “This mandarin is the famous and highly important Unshû mikan (Unshiu) of Japan. The name satsuma, by which it has become known in the Occident, is credited to the wife of a United States minister to Japan, General Van Valkenberg, who sent trees of it home in 1878. Satsuma is the name of a former province, now Kagoshima Prefecture, on the southern tip of Kyushu Island, where it is believed to have originated.”
It is believed the Satsuma originated about 350-400 years ago. It is a highly cold resistant tree and has survived 120 F. The UC Citrus Research Center in Riverside, CA lists 49 different sub-varieties of the Satsuma, 18 of those are varieties from China that are identified only by number. One of the most common varieties is the Owari Satsuma. The notes and observations from the UC Center read, “Because of its many fine qualities, Satsuma has been the focus of extensive efforts to extend its season of availability. Owari Satsuma trees are cold-hardy, productive, and vigorous-growing, but mature to a small size with a spreading and somewhat drooping character. The fruit varies in shape depending upon the conditions where it is grown, but it is most commonly oblate with a smooth and thin orange rind that is easily peeled. The flesh is bright orange, tender and juicy, seedless, and mild in flavor. The Owari Satsuma is considered to be a mid-season fruit, with its season of harvest being December to January in most areas of California. The fruit itself does not hold well on the tree, but it stores well after harvest.”
Dancy Mandarin – As noted in in the UC collection, the Dancy Mandarin was received as a seedling from the original Dancy tree from Chico Gardens, Chico, Ca, in 1914. The Center lists the ‘Parentage/origins’ as, “ The tree was growing in the orchard of Colonel G. L. Dancy of Orange Mills in 1867. Its parent was a mandarin tree, known as the Moragne “tangierine,” reported to have been growing in the orchard of N. H. Moragne as early as 1843. This tree is believed to have been introduced from Tangiers, Morocco by Major Atway, the previous owner of the Moragne property. Regardless of this variety’s tangled history, its reputed origin of Tangiers gave rise to the term “tangerine” which today seems to refer to any mandarin, not just Dancy.”
The description written in 1967 by Hodgson states, “Although introduced to the industry as early as 1872, its commercial propagation was begun about 1890 by the Rolleston Nursery at San Mateo. Within a few years, Dancy became the leading mandarin variety, a position it has maintained ever since.” Today, only a few ‘Dancy’ groves remain in Florida and a few ‘backyard’ trees. The ‘Dancy’ is the perfect example of the continuously changing preferences of the consumer as well as the never-ending evolution of the citrus industry.
Mandarin Mergers – Cross-breeding of different varieties of citrus was begun at the UC Research Center in 1914 by H.B. Frost to aid the growth and development of the citrus industry, worldwide. The collection is composed of 1800 trees, representing two of each of 900 different citrus varieties and relatives. Examples of the Center’s endeavors to improve the Mandarin include:
Kinnow – The Kinnow, a mandarin hybrid, was developed at the Center by H. B. Frost in 1915 and released in 1935. As described by the Center, “ Kinnow is the most widely-planted mandarin in Pakistan. The tree grows vigorously and has an upright form, with a strong tendency to alternate bearing. The fruit is oblate with a smooth orange rind that does not peel especially well for a mandarin. The flesh is orange, seedy, and has a rich distinctive flavor. Kinnow is mid-season in maturity and holds well on the tree.” The Kinnow was distributed widely and grown commercially in California and Arizona but is now mostly grown in Pakistan and exported to developing countries.
Murcott – Notes and observations (from the Center): “Murcott is the same variety marketed by Florida growers under the name Honey. It is believed to have come out of the U.S. Department of Agriculture citrus breeding program in Florida in the early 1900s.Murcott trees are moderate in size and vigor with a somewhat upright growth habit with willowy branches. The fruit tends to be borne near the outside of the tree. Alternate bearing often occurs in this variety, and if the fruit burden is excessive in the “on” year, the tree may die due to a carbohydrate depletion commonly referred to as “Murcott collapse.” The fruit is medium-sized when the tree is carrying a moderate fruit load. The orange rind is thin, smooth, and peels moderately well.”