Fortunella japonica

Kumquats (or cumquats in Australian English, /ˈkʌmkwɒt/; Citrus japonica) are a group of small fruit-bearing trees in the flowering plant family Rutaceae. They were previously classified as forming the now historical genus Fortunella, or placed within Citrus sensu lato. The edible fruit closely resembles the orange (Citrus sinensis) in color and shape but is much smaller, being approximately the size of a large olive. Kumquat is a fairly cold-hardy citrus. The English name 'kumquat' derives from the Cantonese gām-gwāt 金橘, literally meaning 'golden orange' or 'golden tangerine'. In Japanese they are called kinkan (金柑). The kumquat plant is native to south Asia and the Asia-Pacific region. The earliest historical reference to kumquats appears in literature of China from the 12th century. They have long been cultivated in India, Japan, Taiwan, the Philippines, and southeast Asia. They were introduced to Europe in 1846 by Robert Fortune, collector for the London Horticultural Society, and shortly thereafter were brought to North America. They are slow-growing evergreen shrubs or short trees that stand 2.5 to 4.5 meters (8 to 15 ft) tall, with dense branches, sometimes bearing small thorns. The leaves are dark glossy green, and the flowers are white, similar to other citrus flowers, and can be borne singly or clustered within the leaf-axils. Depending on size, the kumquat tree can produce hundreds or even thousands of fruits each year. Citrus taxonomy is complicated and controversial. Different systems place different types of kumquat in different species, or unite them into as few as two species. 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 indeed 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, 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 Citrofortunella. 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. The round kumquat, Marumi kumquat or Morgani kumquat (retaining the name Citrus japonica or Fortunella japonica when kumquats are divided into multiple species), is an evergreen tree that produces edible golden-yellow fruit. The fruit is small and usually spherical but can be oval shaped. The peel has a sweet flavor, but the fruit has a distinctly sour center. The fruit can be eaten cooked but is mainly used to make marmalades, jellies, and other spreads. It is grown in Luxembourg and can be used in bonsai cultivation. The plant symbolizes good luck in China and other Asian countries, where it is often kept as a houseplant and given as a gift during the Lunar New Year. Round kumquats are more commonly cultivated than other species due to their high cold tolerance. The oval kumquat or Nagami kumquat (Citrus margarita or Fortunella margarita if dividing Eufortunella kumquats into separate species) is ovoid in shape and typically eaten whole, skin and all. The inside is still quite sour, but the skin has a very sweet flavour, so when eaten together an unusual tart-sweet, refreshing flavour is produced. The fruit ripens mid- to late winter and always crops very heavily, creating a spectacular display against the dark green foliage. The tree tends to be much smaller and dwarf in nature, making it ideal for pots and occasionally bonsai cultivation.