The Origin of Citrus – A New Theory?
It has been widely discussed, and generally accepted by those in the field of botany, horticulture, and plant pathology that Citrus originated in Southeast Asia somewhere within or between China, India, and Malaysia. However, a new theory of origin was hypothesized in 2008 by Professor Andrew (G.A.C.) Beattie, School of Science and Health at the University of Western Sydney. He and his colleagues have researched the origin of Citrus from an entirely different vantage point and perspective to propose Citrus evolved in Australasia (the area comprised of Australia, New Zealand, New Guinea, & neighboring islands in the Pacific Ocean).
Beattie points out that the basis of the conclusion that Citrus originated in Southeast Asian does not take into consideration plate tectonics-the movement of the land masses we now refer to as ‘The Continents’ of the world. In the 1960’s and 1970’s the scientific world accepted the theory of plate tectonics: simply stated, about 200 million years ago all the existing land masses were connected in a giant land mass known as Pangea. Fueled by the internal energy of the earth, this land mass slowly split and ‘drifted’ into the geographic world we know today.
Beattie argues that the biogeographic data obtained from the flora and fauna through molecular evidence contradicts that the acknowledged explanation of the movement of Citrus from Southeast Asia through Malesia (the area including the Malay Peninsula, the Philippines, Sumatra, Borneo, Java and surrounding islands) to Australasia. By examining the geographic relationship of Australia to Asia in Pangea, C. Medica, the Citron, the first described species of Citrus, may have originated in Australasia, possibly New Guinea and was dispersed westward to Southeast Asia by equatorial currents and possibly through migrations of birds and bats. “Our views”, Beattie states, are continually being revised as new information, including historical records, becomes available.”
A Citrus ‘hot-spot’
Recent work in the citrus field suggests that about 25 species of fruit should be reunified as part of the Citrus genus. Australasia is home to 13 of these species most of which are classified as a type of lime. Of particular interest are the Microcitrus group and Eremocitrus group:
Microcitrus – This group contains seven species, five native to Australia and two found in New Guinea, some of which are gaining local and international attention:
Australian finger lime (Microcitrus australasica) – Occurs as a shrub or tree in southern Queensland and Northern South Wales. The finger shaped fruit, up to 10cm long, has been recently popularized as a gourmet “bushfood”. The globular juice vesicles of this fruit has prompted the trade name and marketing as "lime caviar ". The finger lime grows wild but an increasing demand for the gourmet garnishes, marmalade, pickles and spice made from the finger lime is promulgating commercial plantings in Australia as well as California.
Australian round lime (Microcitrus australis) – The plant occurs as a shrub or tall narrow tree in the drier rainforest margins of southeast Queensland, from Brisbane northwards. Its fruit is very similar in appearance to commercial limes. Production is limited to wild harvest and small plantings but is becoming of more interest in the citrus world because its survival abilities when hybrid with the finger lime. This cross produces a variety known as the ‘Sydney hybrid’.
Sydney hybrid (Microcitrus virgate) – As described by Swingle in The Citrus Industry Vol. 1 (1967): “This remarkable hybrid was grown from seeds of the Australian round lime, Microcitrus australis, or of the finger-lime, M. australasica, sent to the U.S. Department of Agriculture's Agricultural Research Service by the late J. E. Maiden, director of the Botanical Garden at Sydney, Australia. More than 200 meters of twigs, both large and small, were borne on a single branch, 3 cm in diameter, of a Sydney hybrid growing near Riverside, California, which survived for several decades on land no longer irrigated where citrus trees made little or no growth.”
Eremocitrus – This group contains one species and is commonly known as the Australian desert lime.
Australian desert lime (Eremocitrus glauca) – As described by Swingle, “This species, called "Dooja" by the aborigines and round lime or native orange by the Australians, is native to northeastern Australia. It is readily distinguished from all the other species of Microcitrus (and from Eremocitrus as well) by its globose or slightly pear-shaped, rough-skinned fruits, 2.5 to 5 cm in diameter (about the size of a large walnut), and by its short-stalked pulp-vesicles that taper gradually into blunt tips often more or less deformed and twisted by mutual pressure. The Australian round lime... grows to be a tree 30 to 60 feet high and is the largest of any of the native citrus fruit trees. The fruit is said to be used for preserves in Queensland. This species, which has been introduced into the United States, grows well in California, where it is now fruiting. It is exceeded in vigor, however, by the Sydney hybrid, the result of a natural cross of this species with the finger-lime, Microcitrus australasica."
mouse over pictures for captions – click for expanded view
Commercial Citrus Production In Australia
Introduction of Citrus – Although Australasia may be the point of origin of Citrus, what we recognize today as oranges, were not introduced into the area until 1788. From Herbert John Webber in the History and Development of the Citrus Industry Vol 1 1967:
“The first Citrus was first planted in New South Wales by the colonists of the First Fleet under Captain Arthur Phillip, who sailed for Australia in 1787 with instructions to introduce plants and seeds at his discretion (Bowman, 1955). At Rio de Janeiro, Brazil, where the expedition stopped for one month, the colonists purchased orange, lime, and lemon trees. On arrival at Port Jackson on January 26, 1788, the first work performed was the planting of the seeds and plants obtained in the voyage from England.
Shortly after 1800, an orangery was begun at Seven Hills, which was to become the most famous grove of its day. By 1828, exports of oranges and lemons were being made from New South Wales. An 1828 catalogue of the Botanic Gardens at Sydney lists twenty-one varieties of oranges and mandarins as being grown, the mandarins indicating that trade had been established with China at an early date."
In addition to limes Australia’s diverse climate is ideal to grow a wide range of citrus:
New South Wales (NSW) is the largest citrus region overall with 3 production areas: Riverina with approximately 8,800 hectares planted 50% to Valencia oranges, 40% to Navel oranges and the balance to other varieties – East Coast NSW holds 365 hectares divided between Navels, Valencias & lemons. The Central NSW cultivates 875 hectares about half of which are ‘common orange’ varieties (Hamlin & Salustiana) and the balance divided between Navels & Valencias.
The Murray Valley (which encompasses north west Victoria and south west NSW) is the second largest growing region with approx. 6,600 hectares planted predominantly (63%) to Navels, and the balance (except for a handful of lemons & grapefruit) evenly divided between Valencias and mandarins.
South Australia is the third largest growing area. Production is the region of Riverland and includes 6,300 hectares of mainly Navels, followed by Valencia oranges, then mandarins, a few lemons, and some grapefruit and tangelos.
Queensland is the largest producer of mandarins followed by lemons and other varieties for a total of 3,590 hectares.
Western Australia has a ‘small but growing industry’ with significant new plantings in recent years. A total of 1,560 hectares are grown comprised mostly of Navels, then mandarins, followed by Valencias, grapefruit and a few lemons. Plantings are wide spread throughout the region.
The Northern Territory is the smallest growing area and has seen citrus decline and mangoes increased. A total of 135 hectares are planted mainly to lemons followed by Star Ruby grapefruit.
Current Orange Production
As per the USDA December 2013 GAIN report Australia will harvest for the 2013-14 crop year approximately 21,000 hectares (about 50,000 acres). Total oranges production will be 482,000 metric tons of which 140,000 will be exported, 223,000 consumed domestically as fresh oranges, and 119,000 processed into juice. The top 5 export markets in the 2012-13 crop year were:
1. Hong Kong
5. United States