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Kumquat

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Kumquat
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Sapindales
Family: Rutaceae
Genus: Citrus
Informal group: Kumquats
Kumquat
"Kumquat" in Chinese characters
Chinese name
Chinese金橘
Literal meaning"golden orange"
Vietnamese name
Vietnamesekim quất
Thai name
Thaiส้มจี๊ด
RTGSsomchíd
Korean name
Hangul금귤
Hanja金橘
Japanese name
Kanji金柑
Nepali name
Nepaliमुन्तला (muntala)

Kumquats (/ˈkʌmkwɒt/ KUM-kwot),[1] or cumquats in Australian English, are a group of small, angiosperm, fruit-bearing trees in the family Rutaceae. Their taxonomy is disputed. They were previously classified as forming the now-historical genus Fortunella or placed within Citrus, sensu lato. Different classifications have alternatively assigned them to anywhere from a single species, Citrus japonica, to numerous species representing each cultivar. Recent genomic analysis defines three pure species, Citrus hindsii, C. margarita and C. crassifolia, with C. × japonica being a hybrid of the last two.

The edible fruit closely resembles the orange (Citrus x sinensis) in color, texture, and anatomy, but is much smaller, being approximately the size of a large olive. The kumquat is a fairly cold-hardy citrus.

Etymology[edit]

The English word kumquat is a borrowing of the Cantonese gām gwāt (IPA: [kɐ́m kʷɐ́t̚]; Chinese: 金橘), from gām "golden" + gwāt "orange".[2]

Description[edit]

Kumquat plants have thornless branches and extremely glossy leaves. They bear dainty white flowers that occur in clusters or individually inside the leaf axils. The plants can reach a height from 2.5 to 4.5 metres (8 to 15 feet), with dense branches, sometimes bearing small thorns.[3] They bear yellowish-orange fruits that are oval or round in shape. The fruits can be 2.5–5 centimetres (1–2 inches) in diameter and have a sweet, pulpy skin and slightly acidic inner pulp. The fruit is often eaten whole by humans and has a taste which is sweet and somewhat sour.[4] Kumquat trees are self-pollinating.

Species[edit]

Citrus taxonomy is complicated and controversial. Different systems place various types of kumquats in different species or unite them into as few as two species. Botanically, many of the varieties of kumquats are classified as their own species, rather than a cultivar.[citation needed] Historically they were viewed as falling within the genus Citrus, but the Swingle system of citrus taxonomy elevated them to their own genus, Fortunella. Recent phylogenetic analysis suggests they do fall within Citrus. Swingle divided the kumquats into two subgenera, the Protocitrus, containing the primitive Hong Kong kumquat, and Eufortunella, comprising the round, oval kumquat, Meiwa kumquats,[5] to which Tanaka added two others, the Malayan kumquat and the Jiangsu kumquat. Chromosomal analysis suggested that Swingle's Eufortunella represent a single 'true' species, while Tanaka's additional species were revealed to be likely hybrids of Fortunella with other Citrus, so-called xCitrofortunella.[6]

One recent genomic analysis concluded there was only one true species of kumquat, but the analysis did not include the Hong Kong variety seen as a distinct species in all earlier analyses.[7] A 2020 review concluded that genomic data were insufficient to reach a definitive conclusion on which kumquat cultivars represented distinct species.[8] In 2022, a genome-level analysis of cultivated and wild varieties drew several conclusions. The authors found support for the division of kumquats into subgenera: Protocitrus, for the wild Hong Kong variety, and Eufortunella for the cultivated varieties, with a divergence predating the end of the Quaternary glaciation, perhaps between two ancestral populations isolated south and north, respectively, of the Nanling mountain range. Within the latter group, the oval, round and Meiwa kumquat each showed a level of divergence greater than between other recognized citrus species, such as between pomelo and citron, and hence each merits species-level classification. Though Swingle had speculated that the Meiwa kumquat was a hybrid of oval and round kumquats, the genomic analysis suggested instead that the round kumquat was an oval/Meiwa hybrid.[9]

Kumquat species
Image Scientific name Common name Distribution
Citrus hindsii Hong Kong kumquat China
Citrus crassifolia Meiwa kumquat China, Japan
Citrus margarita oval kumquat, Nagami kumquat Japan
Citrus japonica round kumquat, Marumi kumquat, Morgani kumquat China, Japan
Citrus obovata Jiangsu kumquat, Fukushu kumquat China, Japan
Citrus swinglei Malayan kumquat Malay Peninsula

Hybrids[edit]

Hybrid forms of the kumquat include the following:

Distribution and habitat[edit]

The kumquat plant is native to Southern China.[11][12] The historical reference to kumquats appears in literature of China from at least the 12th century.[3] They have been cultivated for centuries in other parts of East Asia, South Asia, and Southeast Asia.[4] They were introduced into Europe in 1846 by Robert Fortune, collector for the London Horticultural Society,[13] and are now found across the world.[4]

Cultivation[edit]

Illustration, Walter Hood Fitch
Illustration by Walter Hood Fitch

Kumquats are much hardier than citrus plants such as oranges. Sowing seed in the spring is most ideal because the temperature is pleasant with more chances of rain and sunshine. This also gives the tree enough time to become well established before winter. Early spring is the best time to transplant a sapling. They do best in direct sunlight (needing 6–7 hours a day) and planted directly in the ground. Kumquats do well in USDA hardy zones 9 and 10 and can survive in temperatures as low as 18 degrees F (-7 degrees C). On trees mature enough, kumquats will form in about 90 days.

In cultivation in the UK, Citrus japonica has gained the Royal Horticultural Society's Award of Garden Merit[14] (confirmed 2017).[15]

Propagation[edit]

Kumquats do not grow well from seeds and so are vegetatively propagated by using rootstock of another citrus fruit,[11] air layering, or cuttings.[11]

Varieties[edit]

The Nordmann seedless is a seedless cultivar of the Nagami kumquat (Citrus margarita). It is similar to Nagami but with a slightly different shape and lighter skin.[16]

The Centennial Variegated is another cultivar of the Nagami kumquat. It originated from the open pollination of a Nagami kumquat tree. The fruits are striped light green and yellow when underripe, and turn orange and lose their stripes when they ripen. They are oval-shaped, necked, 2.5 inches long and have a smooth rind. They mature in winter.[17] This cultivar arose spontaneously from the oval kumquat (Citrus margarita). It produces a greater proportion of fruit to peel than the oval kumquat, and the fruit are rounder and sometimes necked. Fruit are distinguishable by their variegation in color, exhibiting bright green and yellow stripes,[11] and by its lack of thorns.

The Puchimaru kumquat is a seedless or virtually seedless Japanese kumquat cultivar. It is resistant to citrus canker and citrus scab. The fruit weighs 11–20 grams and is ellipsoid in shape. It has a dark orange rind which is 4 millimeters thick. The juice content is relatively low. The oil glands are somewhat large and conspicuous. It ripens in January.[18]

Uses[edit]

Nutrition[edit]

Kumquats, raw
Fortunella spp.
Nutritional value per 100 g (3.5 oz)
Energy296 kJ (71 kcal)
15.9 g
Sugars9.36 g
Dietary fiber6.5 g
0.86 g
1.88 g
VitaminsQuantity
%DV
Vitamin A equiv.
2%
15 μg
129 μg
Thiamine (B1)
3%
0.037 mg
Riboflavin (B2)
7%
0.09 mg
Niacin (B3)
3%
0.429 mg
Pantothenic acid (B5)
4%
0.208 mg
Vitamin B6
2%
0.036 mg
Folate (B9)
4%
17 μg
Choline
2%
8.4 mg
Vitamin C
49%
43.9 mg
Vitamin E
1%
0.15 mg
MineralsQuantity
%DV
Calcium
5%
62 mg
Iron
5%
0.86 mg
Magnesium
5%
20 mg
Manganese
6%
0.135 mg
Phosphorus
2%
19 mg
Potassium
6%
186 mg
Sodium
0%
10 mg
Zinc
2%
0.17 mg
Other constituentsQuantity
Water82 g

Percentages estimated using US recommendations for adults,[19] except for potassium, which is estimated based on expert recommendation from the National Academies.[20]

A raw kumquat is 81% water, 16% carbohydrates, 2% protein, and 1% fat (table). In a reference amount of 100 grams (3.5 oz), raw kumquat supplies 71 calories and is a rich source of vitamin C (53% of the Daily Value), with no other micronutrients in significant content (table).

Essential oil[edit]

The essential oil of the kumquat peel contains much of the aroma of the fruit, and is composed principally of limonene, which makes up around 93% of the total.[21] Besides limonene and alpha-pinene (0.34%), both of which are considered monoterpenes, the oil is unusually rich (0.38% total) in sesquiterpenes such as α-bergamotene (0.021%), caryophyllene (0.18%), α-humulene (0.07%) and α-muurolene (0.06%), and these contribute to the spicy and woody flavor of the fruit. Carbonyl compounds make up much of the remainder, and these are responsible for much of the distinctive flavor. These compounds include esters such as isopropyl propanoate (1.8%) and terpinyl acetate (1.26%); ketones such as carvone (0.175%); and a range of aldehydes such as citronellal (0.6%) and 2-methylundecanal. Other oxygenated compounds include nerol (0.22%) and Trans-lialool oxide (0.15%).[21]

Gallery[edit]

See also[edit]

References[edit]

  1. ^ "Kumquat". Collins Dictionary. n.d. Retrieved 25 September 2014.
  2. ^ "Kumquat". Online Etymology Dictionary, Douglas Harper. 2020. Retrieved 20 June 2020.
  3. ^ a b "Kumquat (Citrus japonica)" (PDF). Florida Gulf Coast University. Florida. 2015.
  4. ^ a b c Experts from Dole Food Company; Experts from The Mayo Clinic; Experts from UCLA Center for H (2002). Encyclopedia of Foods: A Guide to Healthy Nutrition. Elsevier. p. 182. ISBN 9780080530871.
  5. ^ Swingle, Walter T. (1915). "A new genus, Fortunella, comprising four species of kumquat oranges". Journal of the Washington Academy of Sciences. 5 (5): 165–176. JSTOR 24520657.
  6. ^ Yasuda, Kiichi; Yahata, Masaki; Kunitake, Hisato (2015). "Phylogeny and Classification of Kumquats (Fortunella spp.) Inferred from CMA Karyotype Composition". The Horticultural Journal. 85 (2): 115–121. doi:10.2503/hortj.MI-078.
  7. ^ Wu, Guohong Albert; Terol, Javier; Ibanez, Victoria; López-García, Antonio; Pérez-Román, Estela; Borredá, Carles; Domingo, Concha; Tadeo, Francisco R; Carbonell-Caballero, Jose; Alonso, Roberto; Curk, Franck; Du, Dongliang; Ollitrault, Patrick; Roose, Mikeal L. Roose; Dopazo, Joaquin; Gmitter Jr, Frederick G.; Rokhsar, Daniel; Talon, Manuel (2018). "Genomics of the origin and evolution of Citrus". Nature. 554 (7692): 311–316. Bibcode:2018Natur.554..311W. doi:10.1038/nature25447. hdl:20.500.11939/5741. PMID 29414943.
  8. ^ Ollitrault, Patrick; Curk, Franck; Krueger, Robert (2020). "Citrus taxonomy". In Talon, Manuel; Caruso, Marco; Gmitter, Fred G Jr. (eds.). The Citrus Genus. Elsevier. pp. 57–81. doi:10.1016/B978-0-12-812163-4.00004-8. ISBN 9780128121634. S2CID 242819146.
  9. ^ Zhu, Chenqiao; et al. (2022). "New insights into the phylogeny and speciation of kumquat (Fortunella ssp.) based on chloroplast SNP, nuclear SSR and whole-genome sequencing". Frontiers of Agricultural Science and Engineering. 9 (4): 627. doi:10.15302/J-FASE-2021436. S2CID 247640336.
  10. ^ Citrofortunella microcarpa". Germplasm Resources Information Network. Agricultural Research Service, United States Department of Agriculture. Retrieved 1 June 2014.
  11. ^ a b c d Julia F Morton (1987). "Kumquat, Fortunella sp. Swingle; In: Fruits of Warm Climates, Miami, FL". NewCROP, New Crop Resource Online Program, Center for New Crops and Plant Products, Purdue University. pp. 182–185. Retrieved 3 January 2020.
  12. ^ "citrus fruit". Germplasm Resources Information Network. Agricultural Research Service, United States Department of Agriculture.
  13. ^ "Robert Fortune". The Royal Parks. 29 April 2019. Retrieved 19 May 2023.
  14. ^ "RHS Plantfinder - Citrus japonica". Retrieved 12 January 2018.
  15. ^ "AGM Plants - Ornamental" (PDF). Royal Horticultural Society. July 2017. p. 16. Retrieved 24 January 2018.
  16. ^ "Nordmann Seedless". Givaudan Citrus Variety Collection at UCR. Retrieved 9 January 2024.
  17. ^ "Kumquats / Citrus Pages". citruspages.free.fr. Retrieved 9 January 2024.
  18. ^ Yoshida, Toshio; Nesumi, H.; Yoshioka, T.; Ieki, H.; Ito, Y.; Nakano, M.; Ueno, I.; Yamada, Yoshio; Murase, S.; Takishita, F. (2003). "New kumquat cultivar 'Puchimaru'" (PDF). S2CID 140658196.
  19. ^ United States Food and Drug Administration (2024). "Daily Value on the Nutrition and Supplement Facts Labels". FDA. Archived from the original on 27 March 2024. Retrieved 28 March 2024.
  20. ^ National Academies of Sciences, Engineering, and Medicine; Health and Medicine Division; Food and Nutrition Board; Committee to Review the Dietary Reference Intakes for Sodium and Potassium (2019). Oria, Maria; Harrison, Meghan; Stallings, Virginia A. (eds.). Dietary Reference Intakes for Sodium and Potassium. The National Academies Collection: Reports funded by National Institutes of Health. Washington, DC: National Academies Press (US). ISBN 978-0-309-48834-1. PMID 30844154. Archived from the original on 9 May 2024. Retrieved 21 June 2024.
  21. ^ a b Koyasako, A.; Bernhard, R.A. (1983). "Volatile Constituents of the Essential Oil of Kumquat". Journal of Food Science. 48 (6). Wiley & Sons: 1807–1812. doi:10.1111/j.1365-2621.1983.tb05090.x.

Further reading[edit]

External links[edit]