Everything about Citrus totally explained
Citrus is a common term and
genus of
flowering plants in the family
Rutaceae, originating in tropical and subtropical southeast
Asia. The word
citrus is derived from the
Ancient Greek kedros or its
Latin derivate
cedrus, names applied by the ancient Greeks and Romans to several different trees with fragrant foliage or wood (compare the completely unrelated
cedars).
The
taxonomy and
systematics of the genus are complex and the precise number of natural
species is unclear, as many of the named species are
clonally-propagated
hybrids, and there's genetic evidence that even some wild, true-breeding species are of hybrid origin. Cultivated
Citrus may be derived from as few as four ancestral species. Natural and cultivated origin hybrids include commercially important
fruit such as the
oranges,
grapefruit,
lemons, some
limes, and some
tangerines.
Recent research has suggested that the closely related genus
Fortunella (kumquats), and perhaps also
Poncirus and the Australian
Microcitrus and
Eremocitrus, should be included in
Citrus. In fact, most botanists now classify
Microcitrus and
Eremocitrus as part of the genus
Citrus.
Description
These plants are large
shrubs or small
trees, reaching 5–15 m tall, with
spiny shoots and alternately arranged
evergreen leaves with an entire margin. The
flowers are solitary or in small
corymbs, each flower 2–4 cm diameter, with five (rarely four) white petals and numerous stamens; they're often very strongly scented. The
fruit is a
hesperidium, a specialised berry, globose to elongated, 4–30 cm long and 4–20 cm diameter, with a leathery rind surrounding segments or "liths" filled with pulp
vesicles. The genus is commercially important as many species are cultivated for their fruit, which is eaten fresh or pressed for
juice.
Citrus fruits are notable for their fragrance, partly due to
flavonoids and
limonoids (which in turn are
terpenes) contained in the rind, and most are juice-laden. The juice contains a high quantity of
citric acid giving them their characteristic sharp flavour. They are also good sources of
vitamin C and
flavonoids.
Cultivation
Citrus trees
hybridise very readily - depending on the
pollen source, plants grown from a
Persian Lime's seeds can produce fruit similar to grapefruit. Thus 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 (
diurnal) cool winter. In tropical regions with no winter, citrus fruits remain green until maturity, hence the tropical "green oranges". The
Persian Lime in particular is extremely sensitive to cool conditions, thus it's usually never exposed to cool enough conditions to develop a mature colour. If they're left in a cool place over winter, the fruits will actually change to a yellow colour. Many citrus fruits are picked while still green, and ripened while in transit to supermarkets.
Citrus trees are not generally frost hardy.
Mandarin Oranges (
C. reticulata) tend 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. Tangerines, tangors and
yuzu can be grown outside even in regions with more marked sub-zero degrees in winter, although this may affect fruit quality. A few hardy hybrids can withstand temperatures well below freezing, but don't produce quality fruit. Lemons can be commercially grown in cooler-summer/moderate-winter coastal Southern California, because sweetness is neither attained nor expected in retail lemon fruit. The related
Trifoliate Orange (
Poncirus trifoliata) can survive below −20 °C; its fruit are astringent and inedible unless cooked but a few better-tasting cultivars and hybrids have been developed (see
citranges).
The trees do best in a consistently sunny, humid environment with fertile soil and adequate rainfall or irrigation. Older 'abandoned'
Citrus in low valleyland may suffer, yet survive, the dry summer of Central California's
Inner Coast Ranges. At any age Citrus grows well enough with infrequent irrigation in partial/understory shade, but the fruit crop is smaller. Though broadleaved, they're evergreen and don't drop leaves except when stressed. The
stems of many varieties have large sharp
thorns. The trees flower in the spring, and fruit is set shortly afterward. Fruit begins to ripen in fall or early winter months, depending on cultivar, and develops increasing sweetness afterward. Some cultivars of tangerines ripen by winter. Some, such as the grapefruit, may take up to eighteen months to ripen.
Major commercial citrus growing areas include southern
China, the
Mediterranean Basin (including southern
Spain),
South Africa,
Australia, the southernmost
United States, and parts of
South America. In the
U.S.,
Florida,
California,
Arizona, and
Texas are major producers, while smaller plantings are present in other
Sun Belt states.
As ornamental plants
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. An
orangery was a feature of royal and aristocratic residences through the 17th and 18th centuries. The
Orangerie at the
Palace of the Louvre, 1617, inspired imitations that were not eclipsed until the development of the modern greenhouse in the 1840s. In the United States the earliest surviving orangery is at the
Tayloe House, Mount Airy, Virginia. George Washington had an orangery at
Mount Vernon.
Some modern hobbyists still grow dwarf citrus in containers or greenhouses in areas where it's too cold to grow it outdoors. Consistent climate, sufficient sunlight, and proper watering are crucial if the trees are to thrive and produce fruit. Compared to many of the usual "green shrubs", citrus trees better tolerate poor container care. For cooler winter areas,
limes and
lemons shouldn't be grown, since they're more sensitive to winter cold than other citrus fruits. Hybrids with
kumquats (×
Citrofortunella) have good cold resistance.
Pests and diseases
Citrus plants are very liable to infestation by
aphids,
whitefly and
scale insects (for example
California red scale). Also rather important are the viral infections to which some of these
ectoparasites serve as
vectors such as the aphid-transmitted
Citrus tristeza virus which when unchecked by proper methods of control is devastating to citrine plantations.
European brown snails (
Helix aspersa) can be a problem in California, though laying female
Khaki Campbell and other
Mallard-based
ducks can be used for control.
The foliage is also used as a food plant by the
larvae of
Lepidoptera (
butterfly and
moth) species such as the
Geometridae Hemithea aestivaria (
Common Emerald) and
Gymnoscelis rufifasciata (
Double-striped Pug), or the
Arctiidae Hypercompe scribonia (
Giant Leopard Moth),
H. eridanus,
H. icasia and
H. indecisa.
Production
| Top Ten Citrus Producers — 2005 |
| Country |
Production (Int $1000) |
Footnote |
Production (MT) |
Footnote |
| |
1,167,400 |
C |
3,250,000 |
F |
| |
387,936 |
C |
1,135,000 |
F |
| |
75,432 |
C |
210,000 |
F |
| |
71,840 |
C |
200,000 |
F |
| |
64,656 |
C |
180,000 |
F |
| |
50,288 |
C |
140,000 |
F |
| |
46,696 |
C |
130,000 |
F |
| |
31,610 |
C |
88,000 |
F |
| |
30,532 |
C |
85,000 |
F |
| |
28,018 |
C |
78,000 |
F |
No symbol = official figure,F = FAO estimate, * = Unofficial figure, C = Calculated figure;
Production in Int $1000 have been calculated based on 1999-2001 international prices
Source: Food And Agricultural Organization of United Nations: Economic And Social Department: The Statistical Devision
|
Uses
Culinary
Many citrus fruits, such as
oranges,
tangerines,
grapefruits, and
clementines, are generally eaten fresh. They are typically peeled and can be easily split into segments. Grapefruit is more commonly halved and eaten out of the skin with a spoon. There are special spoons (
grapefruit spoons) with serrated tips designed for this purpose. Orange and grapefruit juices are also very popular
breakfast beverages. More astringent citrus, such as
lemons and
limes are generally not eaten on their own.
Meyer Lemons can be eaten 'out of hand' with the fragant skin; they're both sweet and sour.
Lemonade or
limeade are popular beverages prepared by diluting the juices of these fruits and adding sugar. Lemons and limes are also used as garnishes or in cooked dishes. Their juice is used as an ingredient in a variety of dishes; it can commonly be found in salad dressings and squeezed over cooked meat or vegetables. A variety of flavours can be derived from different parts and treatments of citrus fruits. The
rind and
oil of the fruit is generally very bitter, especially when cooked. The fruit pulp can vary from sweet and tart to extremely sour.
Marmalade, a condiment derived from cooked orange and lemon, can be especially bitter. Lemon or lime is commonly used as a
garnish for water, soft drinks, or cocktails. Citrus juices, rinds, or slices are used in a variety of mixed drinks. The colourful outer skin of some citrus fruits, known as
zest, is used as a flavouring in cooking; the white inner portion of the peel, the pith, is usually avoided due to its bitterness. The zest of a citrus fruit, typically lemon or an orange, can also be soaked in water in a
coffee filter, and drunk.
Medical
Citrus juice also has medical uses; lemon juice is used to relieve the pain of
bee stings. The orange is also used in
vitamin C pills, which prevents
scurvy. Scurvy is caused by vitamin C deficiency, and can be prevented by having 10 milligrams of vitamin C a day. An early sign of scurvy is fatigue. If ignored, later symptoms are bleeding and bruising easily. After consumption, the peel is sometimes used as a facial cleanser.
Before the development of
fermentation-based processes, lemons were the primary commercial source of
citric acid.
List of citrus fruits
The genus
Citrus has been suggested to originate in
Southeast Asia. Prior to human cultivation, it consisted of just a few species:
Papedas
Australian limes
Hybrids and cultivars
Sorted by parentage. As each is the product of (at least) two parent species, they're listed mutliple times.
Citrus maxima-based
- Amanatsu, natsumikan – Citrus × natsudaidai (C. maxima × unknown)
- Grapefruit, Citrus × paradisi (C. maxima × C. × sinensis)
- Imperial Lemon (C. × limon × C. × paradisi)
- Minneola Tangelo (C. reticulata × C. × paradisi)
- Orangelo, Chironja (C. × paradisi × C. × sinensis)
- Oroblanco, Sweetie (C. maxima × C. × paradisi)
- Sweet Orange – Citrus × sinensis (probably C. maxima × C. × reticulata)
- Tangelo – Citrus × tangelo (C. reticulata × C. maxima or C. × paradisi)
- Tangor – Citrus × nobilis (C. reticulata × C. × sinensis)
- Ugli (C. reticulata × C. maxima or C. × paradisi)
- Wilking (C. × nobilis × C. × deliciosa)
Citrus medica-based
Citrus reticulata-based
Unresolved
- Alemow, Colo – Citrus × macrophylla
- Djeruk limau – Citrus × amblycarpa
- Gajanimma, Carabao Lime – Citrus × pennivesiculata
- Ichang Lemon, Ichang papeda – Citrus × ichangensis
- Imperial Lemon (C. × limon × C. × paradisi)
- Iyokan, anadomikan
- Kabosu – Citrus × sphaerocarpa
- Kaffir Lime, makrut – Citrus × hystrix
- Khasi Papeda – Citrus × latipes
- Lemon – Citrus × limon
- Limetta, Sweet Lemon, Sweet Lime, mosambi – Citrus × limetta
- Omani Lime
- Palestine Sweet Lime – Citrus × limettioides
- Persian lime, Tahiti Lime – Citrus × latifolia
- Rough Lemon – Citrus × jambhiri
- Shekwasha, Hirami Lemon, Taiwan Tangerine – Citrus × depressa
- Sudachi – Citrus × sudachi
- Sunki, Suenkat – Citrus × sunki
- Tachibana Orange
- Volkamer Lemon – Citrus × volkameriana
For hybrids with kumquats, see × Citrofortunella. For hybrids with the Trifoliate Orange, see citrange.
See also
Japanese citrus
Footnotes
Further Information
Get more info on 'Citrus'.
|
External Link Exchanges
Do you know how hard it is to get a link from a large encyclopaedia? Well we're different and will prove it. To get a link from us just add the following HTML to your site on a relevant page:
<a href="http://citrus.totallyexplained.com">Citrus Totally Explained</a>
Then simply click through this link from your web page. Our crawlers will verify your link, extract the title of your web page and instantly add a link back to it. If you like you can remove the words Totally Explained and embed the link in article text.
As long as your link remains in place, we'll keep our link to you right here. Please play fair - our crawlers are watching. Your site must be closely related to this one's topic. Any kind of spamming, dubious practises or removing the link will result in your link from us being dropped and, potentially, your whole site being banned. |
