Editing Key lime

{{Short description|Citrus fruit and plant}}
{{Redirect|Mexican lime|the compound used to process maize|calcium hydroxide}}
{{Use British English|date=June 2020}}
{{Speciesbox
| name = Key lime
| image = Lime 01.jpg
| image_caption = 
| genus = Citrus
| species = × aurantiifolia
| authority = (Christm.) [[Walter Tennyson Swingle|Swingle]]
}}

The '''Key lime''' or '''acid lime''' ('''''Citrus'' × ''aurantiifolia''''' or '''''C. aurantifolia''''') is a [[citrus hybrid]] (''[[kaffir lime|C. hystrix]]'' × ''[[citron|C. medica]]'') native to tropical [[Southeast Asia]]. It has a spherical fruit, {{convert|2.5-5|cm||abbr=off|frac=2}} in diameter. The Key lime is usually picked while it is still green, but it becomes yellow when ripe.

The Key lime has thinner [[Peel (fruit)|rind]] and is smaller, seedier, more acidic and more aromatic than the [[Persian lime]] (''Citrus × latifolia''). It is valued for its characteristic flavor. The name comes from its association with the [[Florida Keys]], where it is best known as the [[flavoring]] ingredient in [[Key lime pie]]. The key lime is not to be confused with '''West Indian lime''', '''bartender's lime''', '''Omani lime''', or '''Mexican lime''' which are slightly different. The last is classified as a distinct [[Race (biology)|race]] with a thicker skin and darker green colour. Philippine varieties have various names, including '''''dayap''''' and '''''bilolo'''''.<ref>{{cite web|url=http://www.stuartxchange.org/Dayap.html |title=Dayap / Citrus aurantifolia / LIME: Philippine Medicinal Herbs / Philippine Alternative Medicine |publisher=Stuartxchange.org |access-date=2013-12-20}}</ref>

== Etymology ==
The English word ''lime'' was derived, via [[Spanish language|Spanish]] then [[French language|French]], from the Arabic word {{lang|ar|ليمة}} ''līma'', which is, in turn, a derivation of the [[Persian language|Persian]] word ''limu'' {{lang|fa|لیمو}}.<ref>{{Cite Merriam-Webster|Lime|access-date=2017-09-23}}</ref> ''Key'' is from [[Florida Keys]], where the fruit was naturalised. The earliest known use of the name is from 1905, where the fruit was described as "the finest on the market. It is aromatic, juicy, and highly superior to the lemon."<ref>"[http://www.oed.com/view/Entry/103132?redirectedFrom=key+lime key, n.2]". ''OED Online''. September 2013. Oxford University Press. Accessed 24 October 2013.</ref>

== Description ==
[[File:A tree full of key limes in West Bengal, India.jpg|thumb|A tree full of key limes in [[West Bengal]], India]]
''C. aurantiifolia'' is a shrubby tree, growing to {{convert|5|m|ft|abbr=off}}, with many [[Thorns, spines, and prickles|thorns]]. Dwarf [[Variety (botany)|varieties]] exist that can be grown indoors during winter months and in colder climates. Its trunk, which rarely grows straight, has many branches, and they often originate quite far down on the trunk. The [[leaves]] are ovate, {{convert|2.5-9|cm||frac=2|abbr=off}} long, resembling [[Orange (fruit)|orange]] leaves (the scientific name ''aurantiifolia'' referring to this resemblance to the leaves of ''[[Citrus aurantium]]''). The [[flower]]s are {{convert|2.5|cm|in|0|abbr=on}} 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.<ref>{{cite book|author1=P. Golob|author2=Food and Agriculture Organization of the United Nations |title=The use of spices and medicinals as bioactive protectants for grains |chapter=Alphabetical List of Plant Families with Insecticidal and Fungicidal Properties |chapter-url=https://books.google.com/books?id=99B3ktmecWAC&pg=PA13 |access-date=19 June 2011 |year=1999 |publisher=Food & Agriculture Org. |isbn=978-92-5-104294-6 |pages=13–}} [https://web.archive.org/web/20021218030752/http://www.fao.org/docrep/x2230e/x2230e12.htm Webarchive mirror]</ref><ref name="purdue1">[http://www.hort.purdue.edu/newcrop/morton/mexican_lime.html ''Citrus aurantiifolia'' Swingle]. Hort.purdue.edu. Retrieved on 2011-06-19.</ref>

Skin contact can sometimes cause [[phytophotodermatitis]],<ref name="Weber et al. 1999">{{cite journal |title=Phytophotodermatitis: The other 'lime' disease |last1=Weber |first1=Ian C |last2=Davis |first2=Charles P |last3=Greeson |first3=David M |year=1999 |journal= [[The Journal of Emergency Medicine]] |volume=17 |issue=2 |pages=235–237 |issn=0736-4679 |pmid=10195477 |doi=10.1016/s0736-4679(98)00159-0}}</ref><ref>{{cite web |url=http://www.patientcareonline.com/articles/phytophotodermatitis-fingers-young-child |title=Phytophotodermatitis on Fingers of a Young Child |date=2003-04-01 |website=Patient Care Online |language=en |access-date=2018-10-23}}</ref> which makes the skin especially sensitive to [[ultraviolet]] light.

== Taxonomy ==
{{See also|Citrus taxonomy}}
[[File:Map of inferred original wild ranges of the main Citrus cultivars, and selected relevant wild taxa (Fuller et al., 2017).png|thumb|Map of inferred original wild ranges of the main ''Citrus'' cultivars, and selected relevant wild taxa<ref name="fuller">{{cite book|first1=Dorian Q. |last1=Fuller |first2=Cristina |last2=Castillo |first3=Eleanor|last3=Kingwell-Banham|first4=Ling|last4=Qin|first5=Alison|last5=Weisskopf|editor1-first=Véronique |editor1-last=Zech-Matterne |editor2-first=Girolamo|editor2-last=Fiorentino|title =AGRUMED: Archaeology and history of citrus fruit in the Mediterranean |chapter =Charred pomelo peel, historical linguistics and other tree crops: approaches to framing the historical context of early Citrus cultivation in East, South and Southeast Asia |publisher =Publications du Centre Jean Bérard|year =2017|pages=29–48|isbn =9782918887775|doi=10.4000/books.pcjb.2107|url=https://hal.archives-ouvertes.fr/hal-03501166/file/2017-Ruas-etal-Citrus.pdf |chapter-url =https://books.openedition.org/pcjb/2173?lang=en}}</ref>]]
The Key lime cultivar is a [[citrus hybrid]], ''[[Citrus micrantha]]'' × ''[[Citron|Citrus medica]]'' (a [[Papeda (citrus)|papeda]]-[[citron]] cross).<ref>{{cite journal|title=Next generation haplotyping to decipher nuclear genomic interspecific admixture in ''Citrus'' species: analysis of chromosome 2 |journal=BMC Genetics |volume=15 |page=152 |year=2014 |last1=Curk |first1=Franck |last2=Ancillo |first2=Gema Ancillo |last3=Garcia-Lor |first3=Andres |last4=Luro |first4=François |last5=Perrier |first5=Xavier |last6=Jacquemoud-Collet |first6=Jean-Pierre |last7=Navarro |first7=Luis |last8=Ollitrault |first8=Patrick |doi=10.1186/s12863-014-0152-1 |pmid=25544367 |pmc=4302129 |doi-access=free }}</ref><ref name=GRIN>{{GRIN |''Citrus'' × ''aurantiifolia'' |10683 |access-date=11 December 2017}}</ref><ref name=Nicolosi>{{cite journal |last1=Nicolosi |first1=E. |last2=Deng |first2=Z.N. |last3=Gentile |first3=A. |last4=La Malfa |first4=S. |last5=Continella |first5=G. |last6=Tribulato |first6=E. |year=2000 |title=''Citrus'' phylogeny and genetic origin of important species as investigated by molecular markers |journal=Theoretical and Applied Genetics |volume=100 |issue=8|pages=1155–1166 |doi=10.1007/s001220051419 |s2cid=24057066}}</ref>

The Key lime has given rise to several other lime varieties.  The best known, the [[Polyploid|triploid]] progeny of a Key lime-lemon cross, is the [[Persian lime]] (''Citrus × latifolia''), the most widely produced lime, globally. Others are, like their parent, classed within ''C. aurantiifolia''. [[Backcross]]ing with [[citron]] has produced a distinct group of triploid limes that are also of commercial value to a limited degree, the seedy Tanepeo, Coppenrath, Ambilobe and Mohtasseb lime varieties as well as the Madagascar lemon. Hybridization with a [[mandarin orange|mandarin]]-[[pomelo]] cross similar to the oranges has produced the Kirk lime. The New Caledonia and Kaghzi limes appear to have resulted from an [[F1 hybrid|F2]] Key lime self-pollination, while a spontaneous genomic duplication gave us the [[Polyploid|tetraploid]] Giant Key lime.<ref name="limes and lemons">{{cite journal |title=Phylogenetic origin of limes and lemons revealed by cytoplasmic and nuclear markers |last1=Curk |first1=Franck |last2=Ollitrault |first2=Frédérique |last3=Garcia-Lor |first3= Andres |last4=Luro |first4=François |last5=Navarro |first5=Luis |last6=Ollitrault |first6=Patrick |journal=Annals of Botany |volume=11 |issue=4 |pages=565–583 |year=2016 |doi=10.1093/aob/mcw005 |pmid=26944784 |pmc=4817432}}</ref><ref>{{citation|last1=Ali |first1=Muhammad Amjad |last2=Nawaz |first2=Muhammad Azher |chapter=Advances in Lime Breeding and Genetics |title=The Lime: Botany, Production and Uses |editor-last1=Khan |editor-first1=M. Mumtaz |editor-last2=Al-Yahyai |editor-first2=Rashid |editor-last3=Al-Said |editor-first3=Fahad |year=2017 |publisher=CAB International |pages=37–53}}</ref> The potential to produce a wider variety of lime hybrids from the Key lime due to its tendency to form [[ploidy|diploid]] gametes may reduce the disease risk presented by the limited diversity of the current commercial limes.<ref>{{cite journal|last1=Rouiss |first1=H |last2=Bakry |first2=F |last3=Froelicher |first3=Y |last4=Navarro |first4=L |last5=Aleza |first5=P |last6=Ollitrault |first6=P|title=Origin of ''C. latifolia'' and ''C. aurantiifolia'' triploid limes: the preferential disomic inheritance of doubled-diploid 'Mexican' lime is consistent with an interploid hybridization hypothesis |journal=Annals of Botany |volume=121 |issue=3 |pages=571–585 |year=2018 |doi=10.1093/aob/mcx179 |pmid=29293884 |pmc=5838810}}</ref>

== Distribution and habitat ==
''C. aurantiifolia'' is native to [[Southeast Asia]]. Its apparent path of introduction was through the [[Middle East]] to [[North Africa]], then to [[Sicily]] and [[Andalucia]] and then, via Spanish explorers, to the [[West Indies]], including the [[Florida Keys]]. [[Henry Perrine]] is credited with introducing the Key lime to Florida.<ref name="tequesta">{{cite news |last=Robinson |first=T. Ralph |date=August 1942 |title=Henry Perrine: Pioneer horticulturist of Florida |volume=1 |pages=16–24 |work=Tequesta |publisher=Historical Association of Southern Florida as a Bulletin of the [[University of Miami]] |issue=2 |url=http://digitalcollections.fiu.edu/tequesta/files/1942/42_1_03.pdf |url-status=dead |access-date=28 November 2018 |archive-url=https://web.archive.org/web/20210925094544/http://digitalcollections.fiu.edu/tequesta/files/1942/42_1_03.pdf |archive-date=25 September 2021 |via=[[Florida International University]]}}</ref> From the Caribbean, lime cultivation spread to tropical and subtropical North America, including [[Mexico]], [[Florida]], and later [[California]].

== Cultivation ==
[[File:Dayap or Philippine keylime.jpg|thumb|Key lime is known as ''dayap'' in the [[Philippines]], where it is native]]
=== History ===
In California in the late 19th century, "Mexican" limes were more highly valued than lemons; however, in Florida, they were generally considered weeds. Then, in 1894–95, the [[Great Freeze]] destroyed the Florida lemon groves, and farmers replanted Mexican limes instead; they soon became known as the Florida Key Lime, a "beloved regional crop". But when the [[1926 Miami hurricane]] ripped them up, they were replanted with the hardier, thornless Persian limes.<ref name="parks">Stella Parks. ''BraveTart: Iconic American Desserts'', 2017, {{isbn|0393634272}}, p. 171-173</ref>

Since the [[North American Free Trade Agreement]] came into effect, most Key limes on the United States market have been grown in Mexico, [[Central America]] and [[South America]]. They are also grown in [[Texas]], Florida, and California.

=== Propagation ===
{{See also|Fruit tree propagation}}[[File:keylime-flower.jpg|thumb|right|Flowers of the Key lime plant]]
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. {{Citation needed|date=May 2011}} If the plants are propagated from seed, the seeds should be stored at least 5–6 months before planting.<ref name="CRC handbook">Duke J.A., duCellier J.L. (1993): ''CRC handbook of alternative cash crops'' (page 139-145)</ref> Alternatively, vegetative propagation from cuttings or by [[layering|air layering]] may permit fruit production within one year, and from genetically more predictable lines of plants. Another method, digging around a mature tree to sever roots, will encourage new sprouts that can be transplanted to another location. {{Citation needed|date=May 2011}} Clones are often bud grafted<ref>{{cite web|url=http://aggie-horticulture.tamu.edu/propagation/budding/budding.html|title=T or Shield Budding|work=tamu.edu|access-date=2010-04-12|archive-date=2010-03-05|archive-url=https://web.archive.org/web/20100305092048/http://aggie-horticulture.tamu.edu/propagation/budding/budding.html|url-status=dead}}</ref> into rough [[lemon]] or [[bitter orange]] to obtain strong root stocks.

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 [[Persian lime|tahiti limes]].<ref name="CRC handbook" /> [[Citrus macrophylla|''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,<ref>{{cite web|url=http://www.hort.purdue.edu/newcrop/morton/mexican_lime.html|title=Mexican Lime|year= 1987|pages= 168–172|work= Fruits of warm climates|first=Julia F.|last=Morton|publisher=Purdue}}</ref><ref>{{cite web|url=http://aggie-horticulture.tamu.edu/citrus/limes.htm|title=Home Fruit Production|work=tamu.edu}}</ref> 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.<ref name="CRC handbook" />

=== Harvesting ===
[[File:KeyLime 2010 07 25 0001.jpg|thumb|White Key lime flower in different stages]] <!---probably mislabelled, since real kew lime flowers are purple tinted from outside, this is probably palestinian sweet lime, or limetta, see citrus taxonomy and moroccan citron--->

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.<ref name="CRC handbook" />

=== Postharvest process ===
[[File:Starr 080610-8303 Citrus aurantiifolia.jpg|thumb|Key lime fruits with persistent [[Gynoecium#Carpels|styles]]]]

[[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 {{convert|12.5|and(-)|15.5|°C|0|abbr=on}} at a [[relative humidity]] of 75–85%. Special procedures are employed to control the shelf life; for example, applications of [[Plant hormone|growth regulators]], [[Fruit waxing|fruit wax]], [[fungicide]]s, precise cooling, calcium compounds, [[silver nitrate]], and special packing material. The preferred storage conditions are temperatures of {{convert|9|-|10|°C|abbr=on}} 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.<ref name="Bisen et al., 2012">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 and Technology (2012) 49(6).753-759. (page 139–145)</ref>

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.

=== Yield ===
The yield varies depending on the age of the trees. Five- to seven-year-old orchards may yield about 6&nbsp;t/ha (2.7 tons/acre), with harvests increasing progressively until they stabilise at about 12–18&nbsp;t/ha (5.4–8 tons/acre). Seedling trees take longer to attain their maximal harvest, but eventually out-yield grafted trees.<ref name="CRC handbook" />

==In culture==
The annual Key Lime Festival in [[Key West, Florida]], has been held every year since 2002 over the [[Independence Day (United States)|Independence Day]] weekend and is a celebration of Key limes in food, drinks, and culture, with a significant emphasis on [[Key lime pie]].<ref>{{cite web |url=http://keylimefestival.com/home.htm |title=Key Lime Festival of the Florida Keys |website=KeyLimeFestival.com }}</ref>

== References ==
{{Reflist}}

== External links ==
* {{Wikispecies-inline|Citrus aurantiifolia}}
* {{Commons category-inline|Citrus × aurantiifolia}}
* [http://citeseerx.ist.psu.edu/viewdoc/download?rep=rep1&type=pdf&doi=10.1.1.214.5466 Citrus aurantiifolia (Christm.) Swingle]  [[United States Forest Service]] description
* [http://lemoncitrustree.com/store/key-lime-tree-history Key Lime Tree History]
* [https://www.nature.com/articles/srep04853 Characterization of limes (Citrus aurantifolia) grown in Bhutan and Indonesia using high-throughput sequencing]

{{Citrus}}
{{Taxonbar|from=Q165354}}
{{Authority control}}

[[Category:Citrus]]
[[Category:Citrus hybrids]]
[[Category:Fruit trees]]
[[Category:Limes (fruit)]]