Citrus japonica

kumquat in flower


Citrus japonica

Thunb. 1780

pronounced: SIT-russ jah-PON-ih-kuh

(Rutaceae — the hibiscus family)

synonym — Fortunella japonica

(Thunb.) Swingle 1915

pronounced: for-tun-ELL-uh jah-PON-ih-kuh

common names: kumquat, cumquat

Citrus is the Latin word for the citrus tree; japonica is botanical Latin for ‘from Japan”. In the synonym, Fortunella is named for Robert Fortune, 19th century Scottish horticulturist and plant collector in China for the Royal Horticultural Society of London. He introduced the kumquat into England in 1846. Originally placed in the Citrus genus, kumquats were given their own Fortunella genus in 1915, although this genus is disputed by many botanists who prefer to keep them in Citrus. The words ‘kum quat’ mean ‘gold orange’ in Chinese.

Kumquats almost certainly originated in China, appearing in literature from the 12th century. They have long been cultivated in Japan (hence the specific), and are now also grown extensively in Taiwan, south-east Asia, the Middle East, Mediterranean Europe, southern Pakistan, and the southern United States. They are much hardier than other citrus plants such as oranges. The Nagami kumquat, which was the one Fortune brought to England, requires a hot summer (25 – 38ºC), but can withstand frost down to –10ºC without injury. They originate from the tea hills of Hunan, China, where the climate is too cold for other citrus fruits. The trees also differ from other citrus in that they enter into a period of winter dormancy so profound that they will remain in it through several weeks of subsequent warm weather without putting out new shoots or blossoms. Despite their ability to survive low temperatures, kumquat trees grow better and produce sweeter fruits in warmer regions.

These are slow-growing evergreen shrubs or short trees from 2.5 – 4.5 m tall, with sparse branches that are light green and angled when young, thornless or with a few spines.

The leaves are alternate, lanceolate, 3 – 8 cm long, finely toothed from the apex to the middle, dark green, glossy above, lighter beneath.

Sweetly fragrant white flowers are borne singly or up to 4 together in the leaf axils.

The fruit is ovoid-oblong or spherical (depending on variety), up to about 4 cm in diameter; the peel is golden yellow to reddish orange, with large, conspicuous oil glands, fleshy, thick, tightly clinging, edible, the outer layer spicy, the inner layer sweet; the pulp is scant, in 3 – 6 segments, not very juicy, acid to sub-acid, and contains small pointed seeds, or sometimes none. The plants are rarely grown from seed, as they do not do well on their own roots. They are usually grafted on to some type of orange. The bush lemon, used as root-stock for so many other citrus varieties, is not very suitable for kumquats, as it tends to be too vigorous for the slow-growing kumquat. In Australia in particular, kumquats are commonly grown as a standard, and often in tubs.

To my mind, the best marmalade of all is made from kumquats. There is a distinctive ‘sweet and sour’ flavour imparted by the peel that other marmalades cannot equal. This preserve, home-made, is often found on church fund-raising stalls and the like, but it has been difficult to find it made commercially either in Australia or in the UK. There are now, however, a couple of Australian producers offering it on the internet.

In China and Taiwan they preserve or candy the fruits, and these are often served as desserts in Chinese restaurants. The fruit is also pickled whole, or used as an ingredient in mixed pickles.

Today the kumquat tree remains a sacred symbol of the Chinese lunar New Year. The fruit signifies gold and good fortune.


Photographs taken in Arcadia 2010
Page last updated 10th November 2018