citrus

A member of a group of plants bearing distinctive juicy, acid-tasting fruits of great economic importance. The majority belong to the genus Citrus, but a few come from close relatives. All species are spiny evergreen shrubs or trees; ovoid, dark green, glossy leaves with an articulated joint at the junction of blade and stalk; the stalk often winged, sometimes to the extent of appearing as a second blade attached end-to-end to the first. The leaves of side shoots become modified to form spines. Flowers and fruits are borne on the tree at the same time; the fragrant flowers solitary or in small clusters in the axils of the leaves, with 45 sepals and 48 white fleshy petals. The fruit is a type of berry, in which the carpels (the familiar segments containing the seeds or pips buried in a pulpy flesh composed of specialized hair-cells) are enclosed in a thick, leathery rind. Both the foliage and rind of the fruit have numerous glands containing aromatic essential oils.

Most Citrus species are cultivated, along with numerous cultivars. They include well-known species such as orange, lemon, lime, grapefruit, as well as more local fruits, such as the shaddock. Citrus fruits originated in China and SE Asia, but have been cultivated in many areas since early times, and a number are of obscure parentage. They are now grown in the tropics and warm temperate regions throughout the world, mainly the Mediterranean, S USA, S Africa, and Australia, and have become a major export crop for several countries. Breeding experiments to produce improved varieties and new and exotic hybrids are common. Although many citrus fruits are grown for eating, either as fresh fruit or in marmalade and preserves, some (eg bergamot orange) are grown for their essential oils, important in the perfume industry. (Genus: Citrus, 12 species. Family: Rutaceae.)

iCitrus

Citrus reticulata

Scientific classification

Kingdom:	Plantae
Division:	Magnoliophyta
Class:	Magnoliopsida
Subclass:	Rosidae
Order:	Sapindales
Family:	Rutaceae
Genus:	Citrus L. major hybrids
Species Citrus aurantifolia - Key lime Citrus maxima - Pomelo Citrus medica - Citron Citrus reticulata - Mandarin & Tangerine Major hybrids Citrus ×sinensis - Sweet Orange Citrus ×aurantium - Bitter Orange Citrus ×paradisi - Grapefruit Citrus ×limon - Lemon Citrus ×latifolia - Persian lime See also main text for other hybrids

Citrus is a common term and genus of flowering plants in the family Rutaceae, originating in tropical and subtropical southeast Asia.

Citrus fruits are notable for their fragrance, partly due to terpenes contained in the rind, and most are juice-laden. Numerous natural and cultivated origin hybrids include commercially important fruit such as the orange, lemon, grapefruit, and some tangerines.

Cultivation

As citrus trees hybridise very readily (e.g., seeds grown from Persian limes can produce fruit similar to grapefruit), all commercial citrus cultivation uses trees produced by grafting the desired fruiting cultivars onto rootstocks selected for disease resistance and hardiness.

The colour of citrus fruits only develops in climates with a cool winter. In tropical regions with no winter, citrus fruits remain green until maturity, hence the tropical "green orange". Many citrus fruits are picked while still green, and ripened while in transit to supermarkets.

Citrus trees are not generally frost hardy. Citrus reticulata tends to be the hardiest of the common Citrus species and can withstand short periods down to as cold as −10 °C, but realistically temperatures not falling below −2 °C are required for successful cultivation.

Major commercial citrus growing areas include southern China, the Mediterranean region, South Africa, Australia, the southernmost United States, and parts of South America.

Citrus trees grown in tubs and wintered under cover were a feature of Renaissance gardens, once glass-making technology enabled sufficient expanses of clear glass to be produced.

Some modern hobbyists still grow dwarf citrus in containers or greenhouses in areas where it is too cold to grow it outdoors. For cooler areas, lime and lemon should not be grown, since they are more sensitive to cold than other citrus fruits. Also rather important are the viral infections to which some of these ectoparasites serve as vectors such as the aphid-transmited Citrus tristeza virus which when unchecked by proper methods of control is very devastating to citrine plantations.

Uses

Culinary

Many citrus fruits, such as oranges, tangerines, grapefruits, and clementines, are generally eaten fresh. More astringent citrus, such as lemons and limes are generally not eaten on their own. A variety of flavours can be derived from different parts and treatments of citrus fruits.

Medical

Citrus juice also has medical uses - the lemon juice is used to cure bee stings.

History

Prior to human cultivation, the genus Citrus originated in Southeast Asia and consisted of just a few species:

Citrus maxima, the pummelo, from the Malay archipelago Citrus medica, the citron, from India Citrus aurantifolia, the key lime, from India Citrus reticulata, the mandarin and similar, from China Citrus halimii, a more recent discovery, from Thailand and Malaya

List of citrus fruits

Alemow, Colo, C. medica Calamondin (Calamansi) Citron Citrus medica Clementine Daidai, Seville, Sour Orange, Citrus aurantium Dekopon- hybrid between ChungGyun mandarins and Ponkan Desert Lime, Citrus glauca (syn. ×amblycarpa, Indonesia Finger Lime, Citrus australasica, (syn. ×paradisi Ichang Lemon Citrus ×ichangensis Imperial lemon Citrus limon × Citrus ×paradisi Iyokan Kabosu Citrus sphaerocarpa Kaffir lime Citrus ×hystrix Key lime Citrus aurantifolia Kinnow Khasi pepeda, C. forms hybrids with Citrus (see Citrofortunella) Lemon Citrus ×limon Lime Citrus aurantifolia limetta, Sweet Lemon C. ×natsudaidai Orange Citrus sinensis Orangelo: Chironja Orangequat Oroblanco Persian lime, Tahiti lime Citrus ×latifolia Pomelo, Pummelo, Shaddock, Citrus grandis Ponderosa lemon Ponkan Rangpur, Lemanderin Citrus ×limonia Rough Lemon C. ×sunki Sweetie Sweet Lime, Sweet Lime, Central America, C. ×limettioides Tachibana Orange Tangelo: Minneola tangelo Ugli Tangerine Citrus reticulata Tangor C.