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Citrus ID






Swingle and Reece (1967) noted that:

"The citron was the first citrus fruit to reach the Mediterranean region. Apparently it was introduced to the eastern Mediterranean area following the invasion of Persia by Alexander the Great about 325 B.C. Theophrastus (writing about 310 B.C.) called the citron the Median or Persian apple. He said that it was inedible but very fragrant and a remedy for rheumatism and sore mouth, as well as a repellent to drive away moths. Engler stated (1931, p. 338): "Since the fruits had the same uses as the wood of the Sandarak tree, Callitris quadrivalvis, the [ancient] name of this wood 'Citrus' was transferred to the fruit as Mala citrea. " This renaming of the Median apple as the Citrus apple led to the transfer of the name "Citrus" first to the citron and later to other citrus fruits.

The native home of the citron has not been determined with certainty. The citron is commonly supposed to be indigenous to India but J. D. Hooker, who said (1875, p. 514) that he had no doubt about the citron's being truly wild when he found it growing "mainly on dry sunny slopes [in Sikkim] totally unsuited for any kind of cultivation…," later came to doubt its being indigenous. Bonavia (1888, p. 70) stated: "I am still in doubt whether it [the citron] is indigenous in India. It does not appear to have any ancient Sanskrit name and the number of varieties, if they are variations, on the western seacoast is suggestive. It is curious that they should be found in the area which came most in contact with foreigners."

The citron has been grown since ancient times in China, but Chi Han, minister of state under the Emperor Hui Ti, in a work written about 300 A.D. (Nan fang ts'ao mu chuang ) mentioned the arrival, in 284 A.D., as tribute to the Chinese Emperor, of 40 Chinese bushels of citrons from Ta-ch'in (a name usually meaning the Roman Empire). He stated: "…the Barbarians value the citron very highly. It is aromatic and its flesh is very thick and white…" This early Chinese record of the citron would indicate that it was not indigenous to China but had been introduced from the West.

The early advent of the citron in Media and Persia, and its subsequent slow penetration into India and China, could be explained easily if the citron should prove to be a native of southern Arabia. The bael fruit of India, Aegle marmelos, has no close relatives in Asia, but three closely allied genera, Aeglopsis, Afraegle, and Balsamocitrus, are found in Africa. Citropsis, an African genus of the Near-Citrus Fruit Trees closely related to the Asiatic genus Atalantia , has eleven species. It would not be surprising to find midway between India and Africa, in some mountain oasis within the tropical zone in Arabia, the citron growing in a wild state. Over a century ago Wellsted (1838, vol. 1, pp. 126-52) found gardens in the Jebel Akhbar Mountains (150 km southwest of Mascat) where grapes grew abundantly; also "pomegranates, citrons, almonds, nutmegs and walnuts with coffee bushes." Over thirty years ago Bartram Thomas (1932, map, p. 101) explored thoroughly the Qara mountain range, about 1,100 km farther to the southwest, and found it to be "an Arcadia of luxuriant forests that clothe steep mountains with perennial streams." In these mountains, situated in a summer rain belt along the coconut-fringed shores of the Arabian Sea, Thomas found giant, large-fruited wild fig trees and "wild-growing, bitter, limes" fruiting abundantly, as well as an extensive growth of frankincense trees at elevations of from 2,000 to 2,500 feet above sea level. Search should be made in this region, between eastern Hadhramaut and Oman, for the native home of the citron."

The Citrus Budwood Facility (2010) provided the following notes on the group (clone DPI-201-1): "India, grown in the Mediterranean area, earliest reference 13th century BC."



Crown compact or dense, not weeping. First-year twig surface glabrous; second- and third-year twig surface mottled or striate; thorns straight; prickles absent or not persistent. Petiole glabrous, length short; wings absent. Leaflets one, margins crenate/crenulate, bluntly toothed or serrate/serrulate, shade leaflet blades flat or weakly conduplicate, sun leaflet blades weakly or strongly conduplicate. Scent of crushed leaflets freshly lemon-like. Fruit as broad as long or longer than broad; rind green-yellow (6), yellow (7-10), yellow-orange (11), or orange (12); rind texture smooth (1-3), slightly rough (4-5), or medium rough (6-7); firmness leathery; navel absent; flesh yellow; taste sour.

Swingle and Reece (1967) provided the following additional notes on the species:

"A shrub or small tree of irregular habit of growth; twigs angled and purplish when young, soon cylindrical, glabrous, with stout, short, single spines in the axils of the leaves; leaves glabrous, elliptic-ovate or ovate-lanceolate, bluntly pointed or rounded at the tips, cuneate or rounded at the base, margins serrate; petioles short, wingless or narrowly margined, not clearly articulated with the leaf blade; inflorescences short, few-flowered racemes; flower buds large, purplish; flowers perfect or male by more or less complete abortion of the pistil; petals 5, pinkish on the outside; stamens very numerous, 30-40 or even 60 as found by Webber (1923, pp. 112-20); ovary large, bulged, cylindrical, with 10-13 locules, tapering into the thick style, which is sometimes persistent; fruit large, oblong or oval, surface smooth or more often rough and bumpy, fragrant, yellow when ripe, rind very thick, segments small, filled with pale greenish pulp-vesicles with acid or sweetish pulp; seeds numerous, small, 9-10 X 4-5 X 3-4 mm, pointed at the base, smooth; embryo white."

The Citrus Budwood Facility (2010) provided the following additional notes on the group (clone DPI-201-1): "Description: Everflowering, everbearing, cold sensitive, monoembryonic, inedible, fragrant, candied peel."



Swingle and Reece (1967) additionally noted that:

"The gradual increase in use of the citron can be traced in early literature. Theophrastus, writing at Babylon about 310 B.C., said the citron "was not eaten." Plutarch, writing between 81 A.D. and 96 A.D., stated that "many substances which in the past people would neither taste nor eat, are considered today as very agreeable.…Shall we mention the cucumber, the melon, the Median apple, and pepper?" (Tolkowsky, 1938, p. 91). By the second century the epicurean Apicius Caelius could recommend the following dishes as being exceptionally delicate: (1) the white inner part of the peel of citron made up into a salad, and (2) small pieces of citron peel served with fish mixed with herbs, vinegar, oil, and spices (Tolkowsky, 1938, p. 59). Before long citrons had become a prized article of food in Rome, and in 301 A.D. the records show that their sales prices were officially fixed by Diocletian at values ranging from twelve to sixteen times the price of melons.

A method of candying citron peel was finally discovered in the Mediterranean region. This involved the softening and clearing of the peel, before in[sic] was candied, by fermentation in sea water through the addition of a mixed culture of a yeast and a bacillus. Candied citron peel ultimately supplanted almost completely the use of fresh peel. However, as the fresh citron peel, like that of lemon and orange, contains hesperidin (Penzig, 1887, p. 286), it is probable that it will prove to be a good source of vitamin P because of its thick mesocarp, in which the hesperidin is found. The peel should be tested for the making of "citrin")."



Bayer, R.J., D.J. Mabberley, C. Morton, C.H. Miller, I.K. Sharma, B.E. Pfeil, S. Rich, R. Hitchcock, and S. Sykes. 2009. A molecular phylogeny of the orange subfamily (Rutaceae: Aurantioideae) using nine cpDNA sequences. American Journal of Botany 96: 668–685.

Bonavia, E. 1886. On the probable wild source of the whole group of cultivated true limes (Citrus acida Roxb., C. medica var. acida of Brandis, Hooker and A. de Candolle). Linnean Society Journal of Botany 22: 213–218.

Chiefland Budwood Facility. 2010. 2010 Annual report July 1, 2009 - June 30, 2010. Bureau of Citrus Budwood Registration, Florida Department of Agriculture & Consumer Services, Winter Haven.

Cottin, R. 2002. Citrus of the World: A citrus directory. Version 2.0. France: SRA INRA-CIRAD.

Engler, A. 1931. Rutaceae. In: Engler, A., and K. Prantl. Die natürlichen Pflanzenfamilien. 19a: 187–359. Engelmann, Leipzig.

Hooker, J.D. 1875–97. The flora of British India. Reeve & Co., London. 7 vol. (Rutaceae, 1: 484–517).

Mabberley, D.J. 1997. A classification for edible Citrus (Rutaceae). Telopea 7: 167–172.

Penzig, O. 1887. Studi botanici sugli agrumi e sulle piante affini. Tip. Eredi Botta, Rome. Ministero di Agricoltura, Industria e Comercio. Annali di Agricoltura, No. 116. 596 pp. and atlas of 58 pls.

Swingle, W.T. and P.C. Reece. 1967. The botany of Citrus and its wild relatives. In: Reuther, W., H.J. Webber, and L.D. Batchelor (eds.). The Citrus industry. Ed. 2. Vol. I. University of California, Riverside.

Thomas, B. 1932. Arabia Felix; across the empty quarter of Arabia. Scribner's, New York. 316 pp.

Tolkowsky, S. 1938. Hesperides: a history of the culture and use of citrus fruits. John Bale Sons & Curnow, London. 371 pp.

Webber, H.J. 1923. Citrus-Arten. In: Früwirth, C. Handbuch der landwirtschaftliche Pflanzenzüchtung. 5: 112–120. Paul Parey, Berlin.

Wellsted, J.R. 1838. Travels in Arabia. John Murray, London. 2 vol.



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Citrus ID Edition 2
October, 2011