Citrus aurantiifolia, key lime (also known as Mexican or West Indian lime), is a thorny shrub or small tree in the Rutaceae (citrus family) that originated in southeast Asia, likely Indonesia and Malaysia, and is cultivated in tropical areas from the West Indies and Central and South America to India, China, and parts of Africa for its flavorful fruit. It is one of several species of Citrus referred to as limes; others include C. hystrix (makrut lime or papeda), C. australasica and C. australis (finger lime and Australian round lime, respectively, both of which are sometimes classified in Microcitrus), and C. glauca (desert lime, sometimes classified in Eremocitrus). C. latifolia, the Persian or Tahitian lime, which is the most widely grown commercial species, can be distinguished from C. aurantiifolia by its larger size, absence of seeds, hardiness, absence of thorns, and longer fruit shelf life.
The most frost-intolerant of the citrus fruits, C. aurantiifolia is a vigorous and drought-resistant shrub or many-branched small tree with numerous sharp spines, 1 cm long (3/8 inch). The leathery, evergreen leaves are alternate, elliptic to oblong, 5 to 7.5 cm (2 to 3 in) long, with narrowly winged stems. The white flowers are solitary or clustered in racemes of 2 to 7; individual flowers are up to 5 cm (2 in) across, with 4 to 6 petals and 20-25 stamens. The small greenish fruits, which ripen to yellow, are generally round to oval or elliptical, around 5 cm (2 in) in diameter, with greenish-yellow, juicy pulp divided into 6 to 15 segments containing few to many small seeds.
C. aurantiifolia was brought to Mediterranean Europe during the Crusades, and then to the Caribbean (likely by the Spaniards) by 1520, where it became locally naturalized throughout the West Indies. It was cultivated in southern Florida and the Florida Keys by the mid-19th century, and became a common “dooryard” fruit, with commercial production in local areas from the 1880s until 1926, when a hurricane destroyed most of the orchards. A public relations campaign to restore the industry, in the 1950s, may have allowed “key lime” to prevail as the common name. This lime is still grown to a limited extent in Florida, but is part of a thriving industry in Dominica, where it is exported to England to be bottled as “Rose’s Lime Juice.”
Key lime, which has a sour, acidic flavor, is sometimes sold as a fresh fruit, but is also widely used for the juice, peels, and the oil obtained from them. Limes are used in sherbet or sorbet, marmalades, jams, and chutneys, and in “Key Lime pie,” although the pie is often made from Persian lime instead. Lime juice is important in sauces and in juice and cocktail beverages, including popular summertime drinks such as daiquiris, mojitos, and Brazilian caiparinhas. Lime juice is low in calories but high in vitamin C. The aromatic leaves are used as a seasoning in Asian cooking. Lime juice is used as a natural remedy to relieve the itch of mosquito bites. In Malaysia and India, the juice is used in traditional medicine to relieve stomach ailments and as an antiseptic, among many other applications.
(Bailey et al. 1976, Morton 1987, van Wyk 2005, Wikipedia 2012.)
Reasons: Widely culitvated and naturalized in tropical and subtropical regions, including southern Florida and Florida Keys, West Indies, and from Mexico to South America. In Puerto Rico, cultivated and escaping or naturalized, chiefly at low elevation.
Root: Decoction for an anthelmintic, contraceptive and for treating venereal disease. Roots are boiled, the water mixed with alcohol, and drunk to abort a fetus up to six weeks old, by the Guyana Patamona. Used for treatment of hemorrhage and for venereal disease in NW Guyana. Leaf: Used three ways in French Guiana: crushed in a maceration for headache; mixed with leaves of Begonia glabra and Ocimum campechianum to bathe very hot feet; mixed with Renealmia guianensis leaves and drunk by the French Guiana Wayapi to induce an abortion. Leaves are boiled and the water used as a medication for colds, by the Guyana Patamona. Fruit: In Guyana, the juice is taken with salt to treat diarrhea. In Guyana, juice is used to treat "viccis", a fever that leads to a desire to sleep and uncontrollably relaxed digestive muscles. Lime juice is drunk to prevent dysentery, and used for cleansing wounds. In Surinam, juice is mixed with oil and rubbed on the stomach to relieve sagging muscles of the sexual organs. Juice from the fruit is mixed with a pinch of salt and drunk for chest colds and fever, by the Guyana Patamona. Juice from the fruit is mixed with grated garlic and some water and drunk for snakebite, by the Guyana Patamona. Juice from the fruit is used for making a tonic, by the Guyana Patamona. Used for treatment of ground itch and for dandruff in NW Guyana.
The Key lime (Citrus aurantiifolia) is a citrusspecies with a globose fruit, 2.5–5 cm in diameter (1–2 in), that is yellow when ripe but usually picked green commercially. It is smaller and seedier, with a higher acidity, a stronger aroma, and a thinner rind, than that of the Persian lime (Citrus × latifolia). It is valued for its unique flavor compared to other limes, with the Key lime usually having a more tart and bitter flavor. The name comes from its association with the Florida Keys, where it is best known as the flavoring ingredient in Key lime pie. It is also known as West Indian lime, bartender’s lime, Omani lime, or Mexican lime, the last classified as a distinct race with a thicker skin and darker green color. Philippine varieties have various names, including dayap and bilolo.
The English word "lime" was derived, via Spanish then French, from the Arabic word ليمة līma (Persian: لیمو limu). "Key" is from Florida Keys, where the fruit is naturalized. The Oxford English Dictionary dates the first use of "key lime" to 1905, in an issue of Country Gentleman, which described the fruit as "the finest on the market. It is aromatic, juicy, and highly superior to the lemon."
C. aurantiifolia is a shrubby tree, to 5 m (16 ft), with many thorns. Dwarf varieties exist which can be grown indoors during winter months and in colder climates. Its trunk rarely grows straight, with many branches, often originating quite far down on the trunk. The leaves are ovate, 2.5–9 cm (1–3.5 in) long, resembling orange leaves (the scientific name aurantiifolia refers to this resemblance to the leaves of the orange, C. aurantium). The flowers are 2.5 cm (1 in) in diameter, are yellowish white with a light purple tinge on the margins. Flowers and fruit appear throughout the year, but are most abundant from May to September in the Northern Hemisphere.
There are various approaches to the cultivation of Key limes. This variety of citrus can be propagated from seed and will grow true to the parent. The seeds must be kept moist until they can be planted, as they will not germinate if allowed to dry out. If the plants are propagated from seed, the seeds should be stored at least 5–6 months before planting. Alternatively, vegetative propagation from cuttings or by air layering may permit fruit production within one year, and from genetically more predictable lines of plants. Or digging around a mature tree to sever roots will encourage new sprouts that can be transplanted to another location. Clones are often bud grafted into rough lemon or sour orange to obtain strong root stocks (see also fruit tree propagation).
It is often advisable to graft the plants onto rootstocks with low susceptibility to gummosis, because seedlings generally are highly vulnerable to the disease. Useful rootstocks include wild grapefruit, cleopatra mandarin and tahiti limes.C. macrophylla is also sometimes used as a rootstock in Florida to add vigor.
Climatic conditions and fruit maturation are crucial in cultivation of the lime tree. Under consistently warm conditions potted trees can be planted at any season, whereas in cooler temperate regions it is best to wait for the late winter or early spring. The Key lime tree does best in sunny sites, well-drained soils, good air circulation, and protection from cold wind. Because its root system is shallow, the Key lime is planted in trenches or into prepared and broken rocky soil to give the roots a better anchorage and improve the trees' wind resistance. Pruning and topping should be planned to maximise the circulation of air and provide plenty of sunlight. This keeps the crown healthily dry, improves accessibility for harvesting, and discourages the organisms that cause gummosis.
The method of cultivation greatly affects the size and quality of the harvest. Trees cultivated from seedlings take 4–8 years before producing a harvest. They attain their maximal yield at about 10 years of age. Trees produced from cuttings and air layering bear fruit much sooner, sometimes producing fruit (though not a serious harvest) a year after planting. It takes approximately 9 months from the blossom to the fruit. When the fruit have grown to harvesting size and begin to turn yellow they are picked and not clipped. To achieve produce of the highest market value, it is important not to pick the fruit too early in the morning; the turgor is high then, and handling turgid fruit releases the peel oils and may cause spoilage.
Shelf life of Key limes is an important consideration in marketing. The lime still ripens for a considerable time after harvesting, and it is usually stored between 12.5 °C to 15.5 °C at a relative humidity of 75–85%. Special procedures are employed to control the shelf life – for example, applications of growth regulators, fruit wax, fungicides, precise cooling, calcium compounds, silver nitrate, and special packing material. The preferred storage conditions are temperatures of 9–10 °C and a humidity over 85%, but even in ideal conditions post-harvesting losses are high.
In India most Key lime producers are small scale farmers without access to such post-harvesting facilities, but makeshift expedients can be of value. One successful procedure is a coating of coconut oil that improves shelf life, thereby achieving a constant market supply of Key limes.
Key limes are made into black lime by boiling them in brine and drying them. Black lime is a condiment commonly used in the Middle East.
The yield varies depending on the age of the trees. Five- to seven-year-old orchards may yield about 6 t/ha (2.7 tons/acre), with harvests increasing progressively until they stabilise at about 12–18 t/ha (5.4–8 tons/acre). Seedling trees take longer to attain their maximal harvest, but eventually out-yield grafted trees.
^Nicolosi, E.; Deng, Z.N.; Gentile, A.; La Malfa, S.; Continella, G. & Tribulato, E., 2000, Citrus phylogeny and genetic origin of important species as investigated by molecular markers. Theoretical and Applied Genetics 100(8): 1155-1166. doi:10.1007/s001220051419 (abstract in HTML).
^ abcdeDuke J.A., duCellier J.L. (1993): CRC handbook of alternative cash crops (page 139-145)
^Bisen A., Pandey S.K., Patel N.: Effect of skin coatings on prolonging shelf life of kagzi lime fruits (Citrus aurantiifolia Swingle). Journal of Food Science Technology (2012) 49(6).753-759. (page 139–145)