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Kumquat

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Kumquats are a group of small, fruit-bearing trees belonging to the Rutaceae family.

Citrus japonica
Citrus japonica

These angiosperm trees produce edible fruits that closely resemble oranges in color, texture, and anatomy. However, kumquats are significantly smaller, typically measuring about the size of a large olive. The name "kumquat" is a borrowing from Cantonese, combining words that mean "golden orange." They are valued globally for their unique flavor and their ability to grow in various climates. Because they are more cold-hardy than many other citrus plants, they are popular in many regions.

The growth and reproduction of a kumquat tree follow a specific biological process. The plants feature thornless branches and extremely glossy leaves. They produce dainty white flowers that appear either individually or in clusters within the leaf axils.

Fortpolyandra
Fortpolyandra

Because kumquat trees are self-pollinating, they can produce fruit without needing pollen from a different tree. Once a tree reaches maturity, the fruit typically forms in about 90 days. For optimal growth, these trees require direct sunlight for six to seven hours every day. They thrive best when planted in the ground in USDA hardy zones 9 and 10.

Taxonomy, the science of classifying living things, is quite complicated regarding kumquats. Historically, scientists debated whether they belonged in the genus Citrus or a separate genus called Fortunella.

Fortunella
Fortunella

The Swingle system once elevated them to the genus Fortunella and divided them into two subgenera: Protocitrus and Eufortunella. Protocitrus contains the primitive Hong Kong kumquat, while Eufortunella includes the round and oval varieties. Recent phylogenetic analysis, which studies evolutionary relationships, suggests that kumquats do actually fall within the Citrus genus. Modern genomic analysis has further clarified these relationships by looking at the plants' DNA.

Recent genomic studies have identified three pure species of kumquat. These are Citrus hindsii, Citrus margarita, and Citrus crassifolia.

Fort-hindsii
Fort-hindsii

The common Citrus × japonica is actually a hybrid resulting from the cross of C. margarita and C. crassifolia. Scientists have also identified specific cultivars, which are varieties produced through cultivation. For example, the Nordmann is a seedless cultivar of the Nagami kumquat, or Citrus margarita. Another variety, the Centennial Variegated, produces fruit with striped green and yellow skin that turns orange as it ripens. The Puchimaru is a Japanese cultivar that is virtually seedless and resistant to citrus canker.

Kumquats have a long history of cultivation and global movement. They are native to southern China, where they have been documented in literature since at least the 12th century. For hundreds of years, they were cultivated throughout Japan and Southeast Asia.

Fortunella obovata Fukushu 0zz
Fortunella obovata Fukushu 0zz

In 1846, the plant was introduced to Europe by Robert Fortune. Fortune was a collector working for the London Horticultural Society. Since his introduction of the plant, kumquats have spread across the entire world. Today, some varieties, like Citrus japonica, have even earned the Royal Horticultural Society's Award of Garden Merit.

The nutritional and chemical makeup of the fruit is quite distinct. A raw kumquat is composed of 81% water, 16% carbohydrates, 2% protein, and 1% fat. It is a rich source of vitamin C, providing about 49% of the Daily Value in a reference amount.

Starr-121108-0788-Fortunella x crassifolia-fruit-Pali o Waipio-Maui (25103025561)
Starr-121108-0788-Fortunella x crassifolia-fruit-Pali o Waipio-Maui (25103025561)

Unlike most citrus, the skin of the kumquat is sweet and pulpy, while the inner pulp is slightly acidic. This allows humans to eat the entire fruit at once. The essential oil in the peel is also notable. It is composed of approximately 93% limonene, which provides much of the fruit's aroma.

Beyond their own species, kumquats are frequently used to create interesting citrus hybrids. By crossing kumquats with other fruits, humans have developed varieties like the calamansi, which is a cross between a mandarin orange and a kumquat. Other hybrids include the limequat, a cross with key lime, and the orangequat, which comes from a Satsuma mandarin.

There are even specialized crosses like the citrangequat and the yuzuquat. These connections show how the kumquat serves as a vital building block in the wider world of citrus horticulture and flavor science.

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🖼️ Images & Media (7)
File:Fort-hindsii.jpg
Fort-hindsii.jpg
File:Starr-121108-0788-Fortunella_x_crassifolia-fruit-Pali_o_Waipio-Maui_(25103025561).jpg
Starr-121108-0788-Fortunella_x_crassifolia...
File:Fortunella.jpg
Fortunella.jpg
File:Citrus_japonica.jpg
Citrus_japonica.jpg
File:Fortunella_obovata_Fukushu_0zz.jpg
Fortunella_obovata_Fukushu_0zz.jpg
File:Fortpolyandra.jpg
Fortpolyandra.jpg
File:A lemon plant (Citrus japonica); flowering and fruiting stem Wellcome V0044760.jpg
A lemon plant (Citrus japonica);...
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