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Citrus

Citrus

Species
Citrus maxima - Pomelo
Citrus medica - Citron
Citrus reticulata - Mandarin & Tangerine
Major hybrids
Citrus x aurantifolia - Key lime
Citrus x aurantium
Citrus x hystrix - Kaffir Lime
Citrus x ichangensis - Ichang Lemon
Citrus x limetta
Citrus x limon - Lemon
Citrus x limonia - Rangpur
Citrus x paradisi - Grapefruit
Citrus x sinensis - Sweet Orange
See also main text for other hybrids Citrus is a common term and genus of flowering plant in the family Rutaceae, originating in tropical and subtropical southeast Asia. The genus contains three species, and numerous natural and cultivated origin hybrids, including commercially important fruit such as the orange, lemon, grapefruit, lime, and tangerine. The taxonomy of the genus is complex, but recent genetic evidence (see e.g. external link cited below) supports the presence of only three species, C. maxima, C. medica and C. reticulata, with all the other taxa previously accepted as species being of hybrid origin between these three. They are large evergreen shrubs or small trees, reaching 5-15 m tall. Citrus is sometimes used as a food plant by the larvae of some Lepidoptera species including Common Emerald and Double-striped Pug.

Citrus fruits

Double-striped Pug Citrus fruits are notable for their fragrance, and most are juice-laden. They contain a high proportion of citric acid giving them their characteristic astringent odour and flavour. They are also good sources of vitamin C, and apparently flavonoids. In botanical terms, "The fruit of all Citrus trees, in which the true fruit is the peel, [is] made up of an outer layer, brightly colored and rich in glands, a spongey whitish mesocarp, and a membraneous endocarp surrounding the segments. The succulent parts we eat is only a secondary tissue developed as a filler" - Paola Lanzara and Mariella Pizzetti Simon & Schuster's Guide to Trees, pp. 44. As citrus trees hybridize very rapidly (e.g., seeds grown from 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". The lime plant in particular is extremely sensitive to cool conditions, thus it is usually never exposed to cool enough conditions to develop a colour. If they are left in a cool place over winter, the fruits will actually change to a yellow colour.

Culture

cultivar 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 [1]. A few hardy hybrids can withstand temperatures well below freezing, but do not produce quality fruit. A related plant, the Trifoliate orange (Poncirus trifoliata) can survive below −20 °C [2] but the fruits produces are extremely astringent and inedible. The trees do best in a consistently sunny, humid environment with fertile soil and adequate rainfall or irrigation. Though broadleaves, they are evergreen and do not drop leaves except when stressed. The trees flower in the spring, and fruit is set shortly afterward. Fruit begins to ripen in fall or early winter months, depending on variety, and develops increasing sweetness afterward. Some varieties of tangerines ripen by winter. Varieties such as the grapefruit may take up to eighteen months to ripen. Major commercial citrus growing areas include southern China, the Mediterranean region, South Africa, Australia, the southernmost United States, and parts of South America. In the U.S., Florida, Texas, and California are major producers, while smaller plantings are present in other Sun Belt states. 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. 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. An orangery was a feature of royal and aristocratic residences through the 17th and 18th centuries. In the United States the earliest surviving orangery is at the Tayloe House, Mount Airy, Virginia. Some modern hobbyists still grow dwarf citrus in containers or greenhouses in areas where it is too cold to grow it outdoors. Consistent climate, sufficient sunlight, and proper watering are crucial if the trees are to thrive and produce fruit. For cooler areas, lime and lemon should not be grown, since they are more sensitive to cold than other citrus fruits. Tangerines, tangors and yuzu can be grown outside even in regions with sub-zero winters, although this may affect fruit quality.

List of citrus fruits

yuzu
- Alemow, Colo, C. x macrophylla
- Amanatsu
- Bergamot orange C. x bergamia
- Bitter orange, Seville Orange
- Buddha's hand, C. medica
- Calamondin (Calamansi)
- Citron Citrus medica
- Clementine
- Golden Lime - hybrid between the genus Citrus and the genus Fortunella
- Daidai, Seville, Sour Orange, Citrus aurantium
- Djeruk limau, C. x amblycarpa, Indonesia
- Gajanimma, Carabao lime, C. x pennivesiculata
- Grapefruit, Sweetie, C. x paradisi
- Ichang Lemon Citrus ichangensis
- Iyokan
- Kabosu
- Kaffir lime Citrus hystrix
- Key lime
- Khasi pepeda, C. x latipes
- Kumquat - in the related genus Fortunella, not Citrus; forms hybrids with Citrus
- Lemon Citrus limon
- Lima, Sweet Lime, Central America, C. x limettioides
- Lime Citrus aurantifolia
- Limetta, C. x limetta
- Limequat
- Mandarin Lime C. x limonia
- Mandarin Orange, Dancy
- Meyer Lemon
- Mikan
- Natsumikan, Japan, C. x natsudaidai
- Orange Citrus sinensis
- Orangelo: Chironja
- Orangequat
- Oroblanco
- Persian lime, Tahiti lime
- Pomelo, Pummelo, Shaddock, Citrus grandis
- Ponkan
- Rangpur, Lemanderin
- Rough Lemon C. x jambhiri
- Satsuma
- Shikwasa, Taiwan tangerine, Hirami lemon, C. x depressa
- Sudachi
- Sunki, Suenkat, C. x sunki
- Tachibana Orange
- Tangelo: Minneola tangelo Ugli
- Tangerine Citrus reticulata
- Tangor C. x nobilis
- Yuzu C. x junos

References and external links

- ¹ [http://www.suite101.com/article.cfm/organic/44712 Grow Organic Citrus]
- ² [http://www.homecitrusgrowers.co.uk/poncirustrifoliata/poncirus.html Home Citrus Growers]
- [http://www.corse.inra.fr/pub95/p95sr10.htm Citrus taxonomy (abstract)]
- [http://www.hort.purdue.edu/newcrop/tropical/lecture_32/lec_32.html Citrus Fruits] from Purdue University Citrus fruits ko:귤속 ja:カンキツ

Pomelo

The pomelo (or pummelo, pommelo or shaddock), Citrus maxima (Merr., Burm. f.), also Citrus grandis (L.), is a citrus fruit, usually a pale green to yellow when ripe, larger than a grapefruit, with sweet flesh and thick spongy rind.

Cultivation and Uses

The pomelo is native to southeastern Asia and all of Malaysia and grows wild on river banks in the Fiji and Friendly Islands. It may have been introduced into China around 100 B.C. It is much cultivated in southern China (Jiangsu, Jiangxi and Fujian Provinces) and especially in southern Thailand on the banks to the Tha Chine River; also in Taiwan and southernmost Japan, southern India, Malaya, Indonesia, New Guinea and Tahiti. It is also grown commercially elsewhere, particularly California and Israel. The pomelo is also called shaddock after an English sea captain, Captain Shaddock, who introduced the seed to the West Indies in the 17th Century from the Malay Archipelago. The pulp color ranges between clear pale yellow to pink to red, and tastes like a sweet grapefruit. It is the largest citrus fruit, growing as large as 30 cm in diameter and weighing as much as 10 kg; the peel is thick, and sometimes used to make marmalade. The grapefruit is a hybrid between the pomelo and the orange. In some markets, grapefruits or pomelo/grapefruit crosses will also be sold as "pomelo" or "pummelo". It can usually be found in grocery stores in the United States from the late fall until early spring and is sometimes thought of as a Christmas fruit. The peel of the pomelo is also used in Chinese cooking or candied. In general citrus peel is often used in southern Chinese cuisine for flavouring, especially in sweet soup desert.

External links

- [http://www.newyorkmag.com/nymetro/food/inseason/10863/ Pomelo]
- [http://www.sfgate.com/cgi-bin/article.cgi?file=/c/a/2004/12/25/HOG7FAFSVC1.DTL&type=printable Pomelo] ja:ブンタン Category:Citrus Category:Southeast Asia

Citroën

Citroën is a French automobile manufacturer, started in 1919 by André Citroën, today part of PSA Peugeot Citroën. Its headquarters are located in Paris, rue Fructidor. Originally a mass-market car maker with relatively straightforward designs, Citroën shocked the world in 1934 with the innovative Traction Avant (front wheel drive) (1934-1956). Until the late 1980s the company had a reputation for approaching auto design in a unique way. Later significant models include the H Van (1947-1981, "HY"), 2CV (1948-1990, The "Ugly Duckling"), DS (1955-1975, "Goddess") and CX (1974-1989).

History

The story of Citroën begins with the founder of the company himself, André Citroën. After serving in the French army, he set up a gear-making business. In 1919, however, the business started to produce automobiles, beginning with the conventional Type A. In 1924, Citroën began a relationship with American engineer Edward Gowan Budd. From 1899, Budd had worked to develop pressed-steel bodies for railroad cars, Pullman in particular. Budd went on to manufacture steel bodies for many automakers, Dodge being his first big auto client. In 1928, Citroën introduced the first all-steel body in Europe. By 1930, Budd had created a prototype for Citroën with a unibody and front wheel drive. It was this prototype that evolved into the Onze Légère and 7 CV (5 kW) Traction Avant of 1934. These cars would set the pattern to be followed thirty years later by the Mini, Volkswagen and nearly every other manufacturer. In the beginning, the cars were successful. But soon competitors, who still used a wood structure for their bodies, introduced aerodynamic body designs on their cars. Citroën had no way to redesign the body of his cars and the cars began to be perceived as old-fashioned. The Citroëns sold in large quantities despite the stylistic drawback, but the car's low price was the main selling point and Citroën experienced heavy losses. That encouraged André Citroën to develop the Traction Avant, a car so innovative that to it the competition would have no response. Achieving quick development of the Traction Avant was, of course, expensive and contributed to the financial ruin of the company. Citroën also sponsored some expeditions in Asia (Croisière Jaune) and Africa (Croisière Noire), intended to demonstrate the potential for motor vehicles to cross inhospitable regions. The expeditions conveyed scientists and journalists and were a publicity success. In 1934, debt forced the company into foreclosure; it was then taken over by its biggest creditor, the tire company Michelin. Citroën unveiled the 2CV at the Paris Salon in 1948. This car become a bestseller and even a 4wd version with 2 engines where sold in limited numbers. 1955 saw the introduction of the DS, which was the first full usage of Citroën's now legendary hydropneumatic suspension system that was first tested on the rear suspension of the last of the Tractions. The DS featured power steering, power brakes and suspension and directional headlights. The same high-pressure system was used to activate pistons located in the gearbox cover to operate the clutch on their "Citromatic", Citroën's version of a semi-automatic transmission. This high-pressure hydraulic system would form the basis of many Citroën cars , including the SM, GS, CX, BX, XM, Xantia and C5. In 1965 Citroën took over the French carmaker Panhard in the hope of using Panhard's expertise in midsize cars to complement its own range of very small, cheap cars (e.g. 2CV/Ami) and large, expensive cars (e.g. DS/ID). In 1967 Citroën took control of Maserati, the Italian sportscar maker and launched the sportscar/Grand Tourer SM, which contained a V6 Maserati engine. This maneuver was unfortunately-timed, with the impending 1973 energy crisis soon to make GT manufacture unprofitable. Huge losses caused by failure of the Maserati tie-up coupled with crippling warranty costs by the unreliable GS and high developement cost of CX led to Peugeot taking over Citroën in 1976. The combined company was known as BX of 1982 still used the hydropneumatic suspension system, but was powered by Peugeot-derived engines. By the late 1980s, PSA used extensive platform sharing. The XM, for example, used the same engines and floorpan as the Peugeot 605, and the Xantia of 1993 was identical under the skin to the Peugeot 406. Peugeot 406 Coupe]] Citroën developed a small car for production in Romania known as the Oltcit, which it also sold as the Citroën Axel. Citroën's ambitious attitude to engineering and styling was squeezed out in favor of Peugeot conservatism. The ubiquitous 2CV was finally killed off in 1990, production having moved from France to Portugal. In spite of the problems between Peugeot and Citroën, Citroën has continued its tradition for innovation, exemplified by new vehicles such as the C2 and the Xsara Picasso. It has even expanded into new markets, for example in China where the C3 and Xsara are alongside the ZX Fukang and Elysée local models. The introduction of even newer models, such as the long-awaited XM replacement, the C6, indicates Citroën's continued commitment to innovation in the 21st century. Proof of this good health, in 2005, for the first time in its history, Citroën is planned to reach a total worldwide production of 1,000,000 cars.

Passenger cars and vans

C6
- 2CV (1948-1990)
- 8CV Rosalie (1932-1935)
- 10CV
- Acadiane (1978-1987)
- Ami 6 (1961-1971)
- Ami 8 (1969-1979)
- Ami Super (1973-1976)
- Axel (1984-1988)
- AX (1986-1998)
- Berlingo (1996- )
- BX (1982-1994)
- CX (1974-1989)
- C1 (2005- )
- C2 (2004- )
- C3 (2003- )
- C4 (2004- )
- C5 (2001- )
- C6 (2005- )
- C7 (2007- )
- C8 (2002- )
- C15 (1984- )
- C25 (1981-1993)
- C35 (1974-1992)
- Dyane (1967-1984)
- DS/ID (1955-1975)
- Elysée ZX derivative for the Chinese market
- Evasion (1994-2002)
- FAF
- GS and GSA (1970-1984)
- H Van (1947-1981)
- Jumpy (1995- )
- Jumper (1994- )
- LN (1976-1979)
- LNA (1978-1986)
- M35 (1970-1971)
- Méhari (1968-1987)
- Saxo (1995-2003 )
- SM (1970-1975)
- Traction Avant (1934-1957)
- TUB (1939-1941)
- Type A (1919-1921)
- Type B (1921-1928)
- Type C C2-C3 (1922-1926)
- Type C C4-C6 (1928-1934)
- Visa (1978-1988)
- XM (1989-2000)
- Xantia (1993-2001)
- Xsara (1997- )
- ZX (1991-1997)

Trucks

- P45 (1934-1953)
- P46
- U23
- 350 to 850 aka Belphegor

Prototypes and Concept Cars

- G Van
- Prototype C or Coccinelle
- C-60
- Project F
- Mini-Zup (1972)
- GS Camargue (1972)
- 2CV Pop (1973)
- Prototype Y
- C44 (1980)
- Karin (1980)
- Xenia (1981)
- Eco 2000 (1984)
- Eole Concept car (1986)
- Zabrus Bertone Concept car (1986)
- Activa (1988)
- Activa II (1990)
- Citella (1992)
- Xanae Concept car 1994
- Osmose Concept car
- Tulip (1995)
- C3 Lumière Concept car (1998)
- C6 Lignage Concept car (1999)
- Osée Pininfarina Concept car
- Pluriel Concept car (1999)
- C-Crosser Concept car (2001)
- C-Airdream Concept car (2002)
- C-Airlounge Concept car (2003)
- C-SportLounge Concept car (2005)
- C-Airplay Concept car (2005)

Miscellaneous

- André Citroën's originally Dutch language family name was Citroen, meaning "lemon", as one of his grandfathers was a citrus seller ("limoenman") on Amsterdam's street markets. An old-fashioned nickname for Citroën cars is Citron (lemon, in French).
- The company's famous "double chevron" logo derives from André Citroën's early business in gear-cutting the company pioneered mass production of double helically-cut gear teeth, which mesh together in a chevron.
- Citroën is a major competitor in the World Rally Championship, winning the constructor title in 2003, 2004 and 2005. In 2004 and 2005, French driver Sébastien Loeb won the Driver's Championship driving the Citroën Xsara WRC.
- Citroën also investigated in the early seventies the possibility to produce helicopters using the Wankel engines manufactured by its subsidiary Comotor. Some models, like the Citroën RE2, have been flight tested and still exist.

Citroën's winners of the European Car of the Year award

- 1971: Citroën GS
- 1975: Citroën CX
- 1990: Citroën XM

Citroen's second and third placed entrants in European Car of the Year award

- 1979: Citroën Visa
- 1988: Citroën AX
- 1994: Citroën Xantia
- 2003: Citroën C3
- 2005: Citroën C4

External links

- [http://www.citroen.com/ Citroën Web Site]
- [http://home.versatel.nl/CitroenWorld/ Citroën World: over 4000 Citroën links]
- [http://www.citroen.mb.ca/citroenet/index.html Citroënët]
- [http://home.versatel.nl/CitroenCrashTest/ Citroën Crash Test]
- [http://home.versatel.nl/CitCity/ CitCity]
- [http://www.icccr.org/ International Citroën Car Club Rallye]
- [http://www.eurovan2.com/ International Forum for C8 Drivers]
- [http://www.theembassyvfx.com/citroen.html Citroën C4 dancing robot commercial] Category:Citroën Category:Peugeot Category:French automobile manufacturers Category:Companies of France ms:Citroën ja:シトロエン

Mandarin orange

The Mandarin orange is a small citrus tree (Citrus reticulata) with fruit resembling the orange. The fruit is oblate, rather than spherical, and roughly resembles a pumpkin in shape. Mandarin oranges are usually eaten plain or in fruit salads. Varieties of mandarin orange include the tangerine, clementine, dancy, tangor, satsuma, mikan and several new varieties such as the Goldnugget recently released by the University of California, Riverside. In some varieties, notably the tangerine, the rind is loose and can easily be removed by hand. The tangor, also called a temple orange, is a cross between a mandarin and an orange. Its thin rind is also easy to peel, and its pale orange pulp is spicy, full-flavored, and tart. Most canned mandarin oranges are satsumas. Citrus fruit varieties are usually self-fertile (needing the bee only to move pollen within the same flower), or parthenocarpic, not needing pollination and therefore seedless. Tangerine blossoms are an exception. They are self sterile, therefore must have a pollenizer variety to supply pollen, and a high bee population to make a good crop. Image:Mandarin_orange_tree.jpg|Mandarin orange tree Image:Mandarin_tree_closeup.JPG|Closeup of Mandarin orange tree Image:Mandarin oranges canned.jpg|Mandarin orange segments Category:Citrus ja:マンダリンオレンジ ms:Limau mandarin

Citrus aurantifolia

The Key lime (Citrus aurantifolia), also known as a Mexican lime, West Indian lime, Bartender's lime, or common lime; has a globose fruit, 2.5-5 cm in diameter (1-2 in), that is greenish-yellow when ripe but usually picked green and valued for its sourness and flavor. The Key lime, along with the larger but less flavorful Persian lime, is one of two citrus fruits identified as sour or acid limes, and often sold generically as a "lime". C. aurantifolia is a shrubby tree, to 5 m (16 ft), with many thorns. Dwarf varieties are popular with home growers and can be grown indoors in winter in colder climates. The trunk rarely grows straight, with many branches that often originate quite far down on the trunk. The leaves are ovate 2.5–9 cm (1–3.5 in) long, resembling orange leaves (the scientific name aurantifolia refers to the leaves' resemblance). The flowers are 2.5 cm (1 in) in diameter, are yellowish white with a light purple tinge on the margins. Flowers and fruit appear throughout the year but are most abundant from May to September . C. aurantifolia is native to Southeast Asia. Its apparent path of introduction was through the Middle East to North Africa and Europe during the Crusades, via Spanish explorers to the West Indies (at some point including the Florida Keys) contemporaneously with Columbus, then tropical and sub-tropical North America including Mexico, Florida, and later California . The English name "lime" was derived from the Persian name لیمو Limu in this course. "Key" would seem to have been added some time after the Persian lime cultivar gained prominence commercially in the United States following the hurricane of 1926 that destroyed the bulk of U.S. C. aurantifolia agriculture, leaving it to grow mostly casually in the Keys . Since the North American Free Trade Agreement came into effect, many key limes are grown in Mexico and Central America. They are also grown in Texas and California. The fruit is smaller, seedier, and less hardy than that of the Persian lime, but has a stronger aroma and acidity, as well as a thinner rind. It is perhaps most distinguished as an ingredient in the eponymous Key lime pie. It is also favored in drinks such as the margarita.

Trivia

This poem is from the well-known modern poet Campbell McGrath's book entitled Florida Poems: :"The Key Lime" :Curiously yellow hand-grenade :of flavor; Molotov cocktail :for a revolution against the bland.

Footnotes

# [http://www.fao.org/docrep/x2230e/x2230e12.htm Alphabetical List of Plant Families with Insecticidal and Fungicidal Properties] # [http://www.hort.purdue.edu/newcrop/morton/mexican_lime.html Citrus aurantifolia Swingle] # [http://www.hort.purdue.edu/newcrop/morton/mexican_lime.html Citrus aurantifolia Swingle] # [http://www.foodreference.com/html/artkeylimes.html Key Limes (Citrus aurantifolia)] # [http://www.hort.purdue.edu/newcrop/morton/mexican_lime.html Citrus aurantifolia Swingle]

References

- [http://www.hort.purdue.edu/newcrop/morton/mexican_lime.html Citrus aurantifolia Swingle]
- [http://www.foodreference.com/html/artkeylimes.html Key Limes (Citrus aurantifolia)]

External links

- [http://www.tonytantillo.com/fruits/limes.html Fruits: Limes] Category:Citrus th:มะนาว

Kaffir lime

The Kaffir lime (Citrus hystrix DC., Rutaceae), also known as Kieffer lime, Makrut, or Magrood, is a Southeast Asian citrus plant with very pungent leaves. The green lime fruits are distinguished by their bumpy exterior and their small size (approx. 4 cm wide), and the hourglass-shaped leaves (actually, the leaf and the leaf-shaped stem or phyllode) are widely used in Thai cuisine and Lao cuisine. Kaffir lime leaves are also popular in the west of Cambodia, but less so in Vietnam. Malay and Indonesian (especially, Balinese; see also Indonesian bay leaf) cuisines use them sporadically with chicken and fish. The leaves can be used fresh or dried, and can be stored frozen. Although the most common product of the kaffir lime tree is its leaves (which impart a sharp lime/neroli flavour to Thai dishes such as tom yum, and to Indonesian food such as sayur assam - literally sour vegetables), the juice and rinds of the small, dark green gnarled fruit (known as jeruk obat - literally medicine citrus) are used in traditional Indonesian medicine. As for the zest, it is widely used in creole cuisine and to impart flavor to "arranged" rums in the Réunion island and Madagascar. For other types of lime, see lime (fruit). Category:Citrus Category:Herbs Category:Spices ms:Limau Purut th:มะกรูด

Citrus limetta

Citrus limetta is a species of citrus, common names for varieties of this species include sweet limetta, Mediterranean sweet lemon, sweet lemon, sweet lime and bitter orange. Category:Trees Category:Citrus Category:Fruit

Lemon

The lemon, Citrus × limon, is a citrus tree, a hybrid of cultivated origin. The fruit are cultivated primarily for their juice, though the pulp and rind (zest) are also used, primarily in cooking or mixing. Lemon juice is about 5% citric acid, which gives lemons a sour taste. This is a small tree, grows to 6 m (20 ft) but usually smaller. The branches are thorny, and form an open crown. The leaves are elliptical-acuminate. Flowers are violet and streaked in the interior and white on the outside. On a lemon tree, flowers and ripe fruits can be found at the same time. The first description of the lemon, which had been introduced from India two centuries earlier, is found in Arabic writings from the 12th century. The origin of the name lemon is through Persian (لیمو Limu), from the Sanskrit nimbuka. They were cultivated in Genoa in the mid-fifteenth century, and appeared in the Azores in 1494. More recent research has identified lemons in the ruins of Pompeii. Lemons were once used by the British Royal navy to combat scurvy, as they provided a large amount of vitamin C. The Royal Navy originally thought lemons were overripe limes which they resemble and their sailors became known as limeys, not lemonies. Both lemons and limes are regularly served as lemonade (natural lemon with water and sugar) or limeade, its equivalent, or as a garnish for drinks such as iced tea or a soft drink, with a slice either inside or on the rim of the glass. Only lemons, however, are used in the Italian liqueur Limoncello. A wedge of lemon is also often used to add flavor to water. Lemon juice is typically squeezed onto fish dishes in restaurants in the United Kingdom and other countries; the acidic juice neutralizes the taste of amines in fish. Lemon juice is also sprinkled on cut fruit, such as apples, to prevent oxidation which would otherwise rapidly darken the fruit, making it less appetizing. Some people like to eat lemons as fruit (however, water should be consumed afterwards, to wash the citric acid and sugar from the teeth, which might otherwise promote tooth decay). A common school experiment involving lemons is to attach electrodes and use them as a battery to power a light. The electricity generated may also be used to power a motor to move the lemons (on wheels) like a car or truck. These experiments also work with other fruit and with potatoes. Propagation is by grafting as the stock is vulnerable to cankers and dry rot. Lemon juice contains approximately 500 milligrams of vitamin C and 50 grams of citric acid per liter. In recent times, the Australian bush food Lemon Myrtle has become a popular alternative to lemons. The crushed and dried leaves and edible essential oils have a strong, sweet lemon taste, but contain no citric acid. Lemon Myrtle is popular in foods that curdle with lemon juice (such as cheesecakes and ice-cream).

External links

- [http://www.botany.com/citrus.html Brief sketches of the history and botany of lemons and other citrus.]
- [http://www.nutritiondata.com/foods-lemon009000000000000000000.html Complete nutritional info.]
- [http://www.rainforestremedies.com.au Rainforest Remedies], international suppliers of Lemon Myrtle.
Image:Lemon 8FruitAndFlower wb.jpg|Lemon fruit and flower Image:Lemon closeup.jpg|Lemon Closeup Image:Lemon02.jpg|Lemons Image:Pair of lemons.jpg|Pair of lemons Image:Lemon tree02.jpg|Lemon tree Image:Lemon_tree_flowers_with_ant.jpg|Lemon tree flowers Image:UnripeLemon4.jpg|unripe lemon Category:Citrus ja:レモン simple:Lemon

Grapefruit

This article is about the citrus fruit. For the Sixties pop band, see Grapefruit (band) The grapefruit is a sub-tropical citrus tree grown for its fruit, which are also known as grapefruit. The evergreen tree is usually found at around 5-6 m tall, although it can reach 13-15 m. The leaves are dark green, long (up to 15 cm) and thin. It produces 5 cm white four-petalled flowers. The fruit is yellow-skinned, largely oblate and ranges in diameter from 10-15 cm and has an acidic yellow segmented pulp. The numerous cultivars include the white grapefruit and the red, of which the 1929 US Ruby Red (of the Redblush variety) has a patent. The fruit has only become popular from the late 19th century, before that it was only grown as an ornamental plant. The US quickly became a major producer of the fruit, with orchards in Florida and Texas. In Spanish the fruit is known as toronja or pomelo. The fruit was discovered in the 1750s, probably in Barbados; currently the grapefruit is said to be one of the "Seven Wonders of Barbados" [http://www.barbados.org/grapefrt.htm]. It had developed as a hybrid of the pomelo (Citrus maxima) with the sweet orange (Citrus sinensis), though it is rather closer to the first than the second. Further crosses have produced the tangelo (1905), the minneola (1931) and the sweetie (1984). The grapefruit was known as the shaddock until the 1800s. Its current name alludes to clusters of the fruit on the tree. Botanically, it was not distinguished from the pomelo until the 1830s, when it was given the name Citrus paradisi. Its true origins were not determined until the 1950s. This led to the official name being altered to Citrus × paradisi. Grapefruit can have a number of interactions with drugs, often increasing the effective potency of compounds. Grapefruit contains naringenin and bergamottin, which inhibit the cytochrome P450 isoform CYP3A4 in the liver. It is via inhibition of this enzyme that grapefruit increases the effects of caffeine, simvastatin, terfenadine, felodipine, nifedipine, verapamil, estradiol, midazolam, tacrolimus, dextromethorphan (significant only at recreational doses), benzodiazepines and cyclosporine A. This effect was responsible for a number of deaths due to overdosing on medication, which lead to its discovery. Grapefruit seed extract is a strong antimicrobial with proven activity against bacteria and fungi. It also has antioxidant properties. Grapefruit forms a core part of the "grapefruit diet", the theory being that the fruit's low glycemic index is able to help the body's metabolism burn fat.

External links

- [http://www.hort.purdue.edu/newcrop/morton/grapefruit.html Grapefruit from "Fruits of warm climates" by Julia F. Morton]
- [http://www.saalfelds.freeserve.co.uk/chelsea.htm World's Northernmost Fruiting Grapefruit?] in the Chelsea Physic Garden, london.
- Heggers JP et al., The effectiveness of processed grapefruit-seed extract as an antibacterial agent: II. Mechanism of action and in vitro toxicity. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12165191&dopt=Abstract abstract]
- [http://www.dietsindex.com/learn/grapefruit-diet.html Grapefruit Diet]- Overview, permitted foods, diet plan, advantages and disadvantages. Category:Citrus Category:Barbados ko:그레이프프루트 ja:グレープフルーツ simple:Grapefruit

Orange (fruit)

Orange—specifically, sweet orange—refers to the citrus tree Citrus sinensis and its fruit. The orange is a hybrid of ancient cultivated origin, possibly between pomelo (Citrus maxima) and tangerine (Citrus reticulata). It is a small tree, growing to about 10 m tall, with thorny shoots and evergreen leaves 4-10 cm long. Oranges originated in southeast Asia, in either India, Vietnam or southern China. The fruit of Citrus sinensis is called sweet orange to distinguish it from Citrus aurantium, the bitter orange.

Cultivation and uses

bitter orange Orange cultivation is a major business and an important part of the economies of the US (Florida and California), most Mediterranean countries, Brazil, Mexico, India, China, Iran, Egypt, Turkey and in lesser extend Pakistan, South Africa and Greece.

World production

The world production of oranges in MT (metric tons) per country (in 2004) is assorted as follows [http://faostat.fao.org/faostat/servlet/XteServlet3?Areas=%3E862&Items=490&Elements=51&Years=2004&Format=Table&Xaxis=Years&Yaxis=Countries&Aggregate=&Calculate=&Domain=SUA&ItemTypes=Production.Crops.Primary&language=EN FAOSTAT];
- 1. Brazil 18,256,500
- 2. USA 11,729,900
- 3. Mexico 3,969,810
- 4. India 3,100,000
- 5. Spain 2,883,400
- 6. Italy 2,064,099
- 7. China 1,977,575
- 8. Iran 1,900,000
- 9. Egypt 1,750,000
- 10. Turkey 1,280,000 The total world production (in MT) was;
- 1974 31,428,199
- 1984 38,979,349
- 1994 54,733,848
- 2004 62,814,424 Between 1974 and 2004 the production increased by 99.8%.

Juice and other products

Oranges are widely grown in warm climates worldwide, and the flavors of orange vary from sweet to sour. The fruit is commonly peeled and eaten fresh, or squeezed for its juice. It has a thick bitter rind that is usually discarded, but can be processed into animal feed by removing water using pressure and heat. It is also used in certain recipes as flavoring or a garnish. The outer-most layer of the rind is grated or thinly veneered with a tool called a zester, to produce orange zest, popular in cooking because it has a flavor similar to the fleshy inner part of the orange. The white part of the rind, called the pericarp or pith, is a source of pectin. pectin Products made from oranges include:
- Orange juice, one of the commodities traded on the New York Board of Trade. Brazil is the largest producer of orange juice in the world, followed by Florida, USA.
- Sweet orange oil, a by-product of the juice industry produced by pressing the peel. It is used as a flavoring of food and drink and for its fragrance in perfume and aromatherapy. Sweet orange oil consists of about 90% d-Limonene, a solvent used in various household chemicals, such as to condition wooden furniture, and along with other citrus oils in grease removal and as a hand-cleansing agent. It is an efficient cleaning agent which is environmentally friendly, and much less toxic than petroleum distillates. It also smells much more pleasant than other cleaning agents.
- The orange blossom, which is the state flower of Florida, is traditionally associated with good fortune, and was popular in bridal bouquets and headwreaths for weddings for some time. The petals of orange blossom can also be made into a delicately citrus-scented version of rosewater.
- Orange blossom honey, or actually citrus honey, is produced by putting beehives in the citrus groves during bloom, which also pollinates seeded citrus varieties. Orange blossom honey is highly prized, and tastes much like orange.
- Fact: There is no word that rhymes with 'Orange'.

Cultivars

pollinates All citrus trees are of the single genus Citrus, and remain largely interbreedable; that is, there is only one "superspecies" which includes lemons, limes and oranges. Nevertheless, names have been given to the various members of the citrus family, oranges often being referred to as Citrus sinensis and Citrus aurantium. All members of the genus Citrus are considered berries because they have many seeds, are fleshy, soft and derive from a single ovary. The Persian orange, grown widely in southern Europe after its introduction to Italy in the 11th c., was bitter; sweet oranges were brought to Europe in the 15th c. from India by Portuguese traders, quickly displaced the bitter, and is now the most common variety of orange cultivated. The sweet orange will grow to different sizes and colors according to local conditions, most commonly with ten carpels, or sections, inside. Portuguese, Spanish, Arab, and Dutch sailors planted citrus trees along trade routes to prevent scurvy. On his second voyage in 1493, Christopher Columbus brought the seeds of oranges, lemons and citrons to Haiti and the Caribbean. They were introduced in Florida (along with lemons) in 1513 by Spanish explorer Juan Ponce de Leon, and were introduced to Hawaii in 1792. A single mutation in 1820 in an orchard of sweet oranges planted at a monastery in Brazil led to the navel orange, also known as the Washington, Riverside or Bahia navel. A single cutting of the original was then transplanted to Riverside, California in 1870, creating a new market worldwide. The mutation causes a 'twin' fruit, with a smaller orange embedded in the outer fruit opposite the stem. From the outside, the smaller, undeveloped twin leaves a formation at the top of the fruit, looking similar to the human navel. Navel oranges are almost always seedless, and tend to be larger than other sweet oranges. They are produced without pollination, through parthenocarpy. The Valencia or Murcia orange is one of the sweet oranges used for juice extraction. It is a late-season fruit, and therefore a popular variety when the navel oranges are out of season. The blood orange has streaks of red in the fruit, and the juice is often a dark burgundy color. The mandarin orange is similar, but smaller and sweeter, and the scarlet navel is a variety with the same diploid mutation as the navel orange. mandarin orange

Etymology

Orange derives from Sanskrit "orange tree", possibly derived from an earlier Dravidic term. The Sanskrit word was borrowed into European languages through Persian nārang, Arabic nāranj, Spanish naranja, Late Latin arangia, Italian arancia or arancio, and Old French orenge, in chronological order. The first appearance in English dates from the 14th century. In Old French and Old English, it used to be referred to as a naranje then an aranje(an orange). The first n was mistaken as the last n of the article. The name of the colour is derived from the fruit, first appearing in this sense in the 1542. Some languages, such as Modern Greek, distinguish the bitter (nerantzi) from the sweet (portokali, ie. "Portuguese") orange.

External links

- [http://www.nutritiondata.com/facts-001-02s01im.html Nutrition data for raw oranges], from [http://nutritiondata.com nutritiondata.com] Category:Citrus Category:Fruit ja:オレンジ simple:Orange th:ส้ม (ผลไม้)

Genus

In biology, a genus (plural genera) is a grouping in the classification of living organisms having one or more related and morphologically similar species. In the common binomial nomenclature, the name of an organism is composed of two parts: its genus (always capitalized) and a species modifier. An example is Homo sapiens, the name for the human species which belongs to the genus Homo. See scientific classification for more details of this system. The type genus of a taxon is usually the first genus to be named and described. Families, and in plants all taxa up to division, are named after the type genus. The genus and these higher taxa are typified by a specimen that shows the characteristics of the genus. The specimen used to describe this species is preserved as the holotype and designated as a generitype in a zoological museum or a herbarium to be available for further study. A generic name in one kingdom is allowed to bear the same name as a genus or other taxon name in another kingdom (though this is discouraged by the International Code of Zoological Nomenclature). For instance, Anura is a genus of plants in the family Asteraceae and the order of frogs; Aotus is the genus of golden peas and night monkeys; Oenanthe is the genus of wheatears and water dropworts, and Prunella is the genus of accentors and self-heal. It is, however, not allowed for two genera within the same kingdom to have the same name. This explains why the platypus genus is Ornithorhynchus — although the name Platypus was chosen by George Shaw in 1799, that name had already been given to the ambrosia beetle by Johann Friedrich Wilhelm Herbst in 1793. Since beetles and platypuses are both member of the kingdom Animalia, the name Platypus could not be used for both. Johann Friedrich Blumenbach published the replacement name Ornithorhynchus in 1800.

Flowering plant

Magnoliopsida - Dicots
Liliopsida - Monocots
The flowering plants (also called angiosperms) are a major group of land plants. They comprise one of the two groups in the seed plants: the flowering plants cover their seeds by including them in a true fruit. They bear the reproductive organs in a structure called a flower; the ovule is enclosed within a carpel, which will lead to a fruit. In the other major group of seed plants, called gymnosperms, the ovule is not enclosed at pollination and the seeds are not in a true fruit, although occasionally fleshy structures may cover the seed (e.g. Taxus).

History

The botanical term "Angiosperm" (Greek: αγγειον, receptacle, and σπερμα, seed) was coined in the form Angiospermae by Paul Hermann in 1690, as the name of that one of his primary divisions of the plant kingdom, which included flowering plants possessing seeds enclosed in capsules, in contradistinction to his Gymnospermae, or flowering plants with achenial or schizo-carpic fruits—the whole fruit or each of its pieces being here regarded as a seed and naked. The term and its antonym were maintained by Carolus Linnaeus with the same sense, but with restricted application, in the names of the orders of his class Didynamia. Its use with any approach to its modern scope only became possible after Robert Brown had established in 1827 the existence of truly naked ovules in the Cycadeae and Coniferae, entitling them to be correctly called Gymnosperms. From that time onwards, so long as these Gymnosperms were, as was usual, reckoned as dicotyledonous flowering plants, the term Angiosperm was used antithetically by botanical writers, but with varying limitation, as a group-name for other dicotyledonous plants. The advent in 1851 of Hofmeister's brilliant discovery of the changes proceeding in the embryo-sac of flowering plants, and his determination of the correct relationships of these with the Cryptogamia, fixed the position of Gymnosperms as a class distinct from Dicotyledons, and the term Angiosperm then gradually came to be accepted as the suitable designation for the whole of the flowering plants other than Gymnosperms, and as including therefore the classes of Dicotyledons and Monocotyledons. This is the sense in which the term is nowadays received and in which it is used here.

Origins

The trend of the evolution of the plant kingdom has been in the direction of the establishment of a vegetation of fixed habit and adapted to the vicissitudes of a life on land, and the Angiosperms are the highest expression of this evolution and constitute the dominant vegetation of the earth's surface at the present epoch. There is no land-area from the poles to the equator, where plant-life is possible, upon which Angiosperms are not found. They also occur abundantly in the shallows of rivers and fresh-water lakes, and in less number in salt lakes and in the sea; such aquatic Angiosperms are not, however, primitive forms, but are derived from immediate land-ancestors. Associated with this diversity of habitat is great variety in general form and manner of growth. The familiar duckweed which covers the surface of a pond consists of a tiny green "thalloid" shoot, one, that is, which shows no distinction of parts—stem and leaf, and a simple root growing vertically downwards into the water. The great forest-tree has a shoot, which in the course perhaps of hundreds of years, has developed a wide-spreading system of trunk and branches, bearing on the ultimate twigs or branchlets innumerable leaves, while beneath the soil a widely-branching root-system covers an area of corresponding extent. Between these two extremes is every conceivable gradation, embracing aquatic and terrestrial herbs, creeping, erect or climbing in habit, shrubs and trees, and representing a much greater variety than is to be found in the other subdivision of seed-plants, the Gymnosperms. The first evidence of angiosperms appears in the fossil record approximately 140 million years ago, during the Jurassic period (203-135 million years ago). Based on current evidence, it seems that the ancestors of the angiosperms and the Gnetophytes diverged from one another during the late Triassic (220-202 million years ago). Fossil plants with some identifiable angiosperm characteristics appear in the Jurassic and early Cretaceous (135-65 million years ago), but in relatively few and primitive forms. The great angiosperm radiation, when a great diversity of angiosperms appear in the fossil record, occurred in the mid-Cretaceous (approximately 100 million years ago). By the late Cretaceous, angiosperms appear to have become the predominant group of land plants, and many fossil plants recognizable as belonging to modern families (including beech, oak, maple, and magnolia) appeared.

Classification

The flowering plants are usually treated as a division. As this is a group above the rank of family there is a free choice of name: Art 16 of the ICBN allows either a descriptive name or a name based on a generic name. The favorite name in the latter category is Magnoliophyta (at the rank of division, based on the Magnolia. The most popular descriptive name is Angiospermae (Angiosperms), with Anthophyta ("flowering plants") a second choice. The internal classification of this group has undergone considerable revision as ideas about their relationships change. The Cronquist system, proposed by Arthur Cronquist in 1981, is still widely used but is no longer believed to reflect phylogeny. A general consensus about how the flowering plants should be arranged has only recently begun to emerge, through the work of the Angiosperm Phylogeny Group, who published an influential reclassification of the angiosperms in 1998. An update incorporating more recent research was published as APG (2003) and is available at the Wikipedia Tree of Life/Update of the Angiosperm Phylogeny Group. Traditionally, the flowering plants are divided into two groups, which in the Cronquist system are called Magnoliopsida (at the rank of class, based on Magnolia) and Liliopsida (at the rank of class, based on Lilium). Much more popular are their descriptive names (as allowed by Art 16 of the ICBN): Dicotyledones (some prefer Dicotyledoneae) and Monocotyledones (some prefer Monocotyledoneae), which have been in use for very long. In English a member of either group may be called a "dicotyledon" (plural "dicotyledons") and "monocotyledon" (plural "monocotyledons"), or more popularly "dicot" (plural "dicots") and "monocot" (plural "monocots"). These names derive from the fact that the dicots often (but not always) have two cotyledons (embryonic leaves) within each seed, while the monocots typically will have one only. From a diagnostic point of view the number of cotyledons is neither a particularly handy nor reliable character. Recent studies show that the monocots are a "good" group (a holophyletic or monophyletic group), while the dicots are not (a paraphyletic group). However, within the dicots a "good" group exists, which includes most of the dicots. This new group is semi-informally called the "eudicots" or "tricolpates". The name "tricolpates" derives from the type of pollen found throughout this group. The name eudicots is formed by preceding "dicot" by the prefix "eu-" (greek 'eu'= "true"), as the eudicots share the characters traditionally attributed to the dicots, such a four- or five-merous flowers. The uninitiate may be tempted to jump to the conclusion that "eudicot" is short for "eudicotyledon" but it is not: the name is eudicot. A formal name that is sometimes used for this group is Rosopsida (at the rank of class, based on Rosa). Separating this group of eudicots from the rest of the (former) dicots leaves a remainder, which sometimes are called informally "palaeodicots" (the prefix "palaeo-" means old, and derives from the classic greek). As this remainder group is not a "good" group this is a term of convenience only.

Families of flowering plants

The most diverse families of flowering plants, in order of number of species, are: palaeodicot flower]] # Asteraceae or Compositae (Daisy family): 26,000 species # Orchidaceae (Orchid family): 20,000 (possibly 30,000) # Fabaceae or Leguminosae (Pea family): 17,000 # Poaceae or Gramineae (Grass family): 9,000 # Rubiaceae (Madder family): 7,000 # Euphorbiaceae (Spurge family): 5,000 # Malvaceae (Mallow family): 4,300 # Cyperaceae (Sedge family): 4,000 In the list above (showing only the 8 largest families), the Orchidaceae, Poaceae, and Cyperaceae are monocot families; the others are dicot families. The total number of families in the flowering plants is over 460.

Internal structure

In internal structure the variety of tissue-formation far exceeds that found in Gymnosperms. The vascular bundles of the stem belong to the collateral type, that is to say, the elements of the wood or xylem and the bast or phloem stand side by side on the same radius. In the larger of the two great groups into which the Angiosperms are divided, the Dicotyledons, the bundles in the very young stem are arranged in an open ring, separating a central pith from an outer cortex. In each bundle, separating the xylem and phloem, is a layer of meristem or active formative tissue, known as cambium; by the formation of a layer of cambium between the bundles (interfascicular cambium) a complete ring is formed, and a regular periodical increase in thickness results from it by the development of xylem on the inside and phloem on the outside. The soft phloem soon becomes crushed, but the hard wood persists, and forms the great bulk of the stem and branches of the woody perennial. Owing to differences in the character of the elements produced at the beginning and end of the season, the wood is marked out in transverse section into concentric rings, one for each season of growth—the so-called annual rings. In the smaller group, the Monocotyledons, the bundles are more numerous in the young stem and scattered through the ground tissue. Moreover they contain no cambium and the stem once formed increases in diameter only in exceptional cases.

Vegetative organs

As in Gymnosperms, branching is monopodial; dichotomy or the forking of the growing point into two equivalent branches which replace the main stem, is absent both in the case of the stem and the root. The leaves show a remarkable variety in form, but are generally small in comparison with the size of the plant; exceptions occur in some Monocotyledons, e.g. in the Aroid family, where in some genera the plant produces one huge, much-branched leaf each season. In rare cases the main axis is unbranched and ends in a flower, as, for instance, in the tulip, where scale-leaves, forming the underground bulb, green foliage-leaves and coloured floral leaves are borne on one and the same axis. Generally, flowers are formed only on shoots of a higher order, often only on the ultimate branches of a much branched system. A potential branch or bud, either foliage or flower, is formed in the axil of each leaf; sometimes more than one bud arises, as for instance in the walnut, where two or three stand in vertical series above each leaf. Many of the buds remain dormant, or are called to development under exceptional circumstances, such as the destruction of existing branches. For instance, the clipping of a hedge or the lopping of a tree will cause to develop numerous buds which may have been dormant for years. Leaf-buds occasionally arise from the roots, when they are called adventitious; this occurs in many fruit trees, poplars, elms and others. For instance, the young shoots seen springing from the ground around an elm are not seedlings but root-shoots. Frequently, as in many Dicotyledons, the primary root, the original root of the seedling, persists throughout the life of the plant, forming, as often in biennials, a thickened tap-root, as in carrot, or in perennials, a much-branched root system. In many Dicotyledons and most Monocotyledons, the primary root soon perishes, and its place is taken by adventitious roots developed from the stem.

The flower, fruit, and seed

- See main article: Flower The characteristic feature of angiosperms is the flower, which shows remarkable variation in form and elaboration, and provides the most trustworthy external characteristics for establishing relationships among angiosperm species. The function of the flower is that of ensuring fertilization of the ovule and development of fruit containing seeds. The floral apparatus may arise terminally on a shoot or from the axil of a leaf. Occasionally, as in violet, a flower arises singly in the axil of an ordinary foliage-leaf. However, more typically, the flower-bearing portion of the plant is sharply distinguished from the foliage-bearing or vegetative portion, and forms a more or less elaborate branch-system called an inflorescence. As in gymnosperms, spores produced by flowers are of two kinds: microspores or pollen-grains, borne in the stamens (or microsporophylls) and megaspores, in which the egg-cell is developed, contained in the ovule and enclosed in the carpel (or megasporophyll). The flower may consist only of these spore-bearing parts, as in willow, where each flower comprises only a few stamens or two carpels. Usually, however, other structures are present and serve both to protect the sporophylls and to form an attractive envelope. The individual members of these surrounding structures are called sepals and petals (or tepals in a flower such as Michelia). The outer series (calyx of sepals) is usually green and leaf-like, and functions to protect the rest of the flower, especially in the bud. The inner series (corolla of petals) is generally white or brightly coloured, and more delicate in structure, and functions in attracting a particular insect or bird by agency of which pollination is effected. This attraction involves colour and scent, and frequently also nectar which is secreted in some part of the flower. These characteristics that attract pollinators account for the popularity of flowers and flowering plants among humans.

Flowering plant sexuality

- See main article: Plant sexuality Flowers are the reproductive structures of flowering plants. The "male" organ is the stamen or androecium, which produces pollen (male spores) in anthers. The "female" organ is the carpel or gynoecium, which contains the egg (female gamete) and is the site of fertilization. While the majority of flowers are perfect or hermaphrodite (having both male and female parts in the same flower structure), flowering plants have developed numerous morphological and physiological mechanisms to reduce or prevent self-fertilization. Heteromorphic flowers have short carpels and long stamens, or vice versa, so animal pollinators cannot easily transfer pollen to the pistil (receptive part of the carpel). Homomorphic flowers may employ a biochemical (physiological) mechanism called self-incompatibility to discriminate between self- and non-self pollen grains. In other species, the male and female parts are morphologically separated, developing on different flowers.

Fertilization

At the period of fertilization the embryo-sac lies in close proximity to the opening of the micropyle, into which the pollen-tube has penetrated, the separating cell-wall becomes absorbed, and the male or sperm-cells are ejected into the embryo-sac. Guided by the synergidae one male-cell passes into the oosphere with which it fuses, the two nuclei uniting, while the other fuses with the definitive nucleus, or, as it is also called, the endosperm nucleus. This remarkable double fertilization as it has been called, although only recently discovered, has been proved to take place in widely-separated families, and both in Monocotyledons and of a prothallium after a pause following the reinvigorating union of the polar nuclei. This view is still maintained by those who differentiate two acts of fertilization within the embryo-sac, and regard that of the egg by the first male-cell, as the true or generative fertilization, and that of the polar nuclei by the second male gamete as a vegetative fertilization which gives a stimulus to development in correlation with the other. If, on the other hand, the endosperm is the product of an act of fertilization as definite as that giving rise to the embryo itself, we have to recognize that twin-plants are produced within the embryo-sac—one, the embryo, which becomes the angiospermous plant, the other, the endosperm, a short-lived, undifferentiated nurse to assist in the nutrition of the former, even as the subsidiary embryos in a pluri-embryonic Gymnosperm may facilitate the nutrition of the dominant one. If this is so, and the endosperm like the embryo is normally the product of a sexual act, hybridization will give a hybrid endosperm as it does a hybrid embryo, and herein (it is suggested) we may have the explanation of the phenomenon of xenia observed in the mixed endosperms of hybrid races of maize and other plants, regarding which it has only been possible hitherto to assert that they were indications of the extension of the influence of the pollen beyond the egg and its product. This would not, however, explain the formation of fruits intermediate in size and colour between those of crossed parents. The signification of the coalescence of the polar nuclei is not explained by these new facts, but it is noteworthy that the second male-cell is said to unite sometimes with the apical polar nucleus, the sister of the egg, before the union of this with the basal polar one. The idea of the endosperm as a second subsidiary plant is no new one; it was suggested long ago in explanation of the coalescence of the polar nuclei, but it was then based on the assumption that these represented male and female cells, an assumption for which there was no evidence and which was inherently improbable. The proof of a coalescence of the second male nucleus with the definitive nucleus gives the conception a more stable basis. The antipodal cells aid more or less in the process of nutrition of the developing embryo, and may undergo multiplication, though they ultimately disintegrate, as do also the synergidae. As in Gymnosperms and other groups an interesting qualitative change is associated with the process of fertilization. The number of chromosomes (see Plant cytology) in the nucleus of the two spores, pollen-grain and embryo-sac, is only half the number found in an ordinary vegetative nucleus; and this reduced number persists in the cells derived from them. The full number is restored in the fusion of the male and female nuclei in the process of fertilization, and remains until the formation of the cells from which the spores are derived in the new generation. In several natural orders and genera departures from the course of development just described have been noted. In the natural Order Rosaceae, the Series Querciflorae, and the very anomalous Genus Casuarina and others, instead of a single macrospore a more or less extensive sporogenous tissue is formed, but only one cell proceeds to the formation of a functional female cell. In Casuarina, Juglans and the Order Corylaceae, the pollen-tube does not enter by means of the micropyle, but passing down the ovary wall and through the placenta, enters at the chalazal end of the ovule. Such a method of entrance is styled chalazogamic, in contrast to the porogamic or ordinary method of approach by means of the micropyle.

Embryology

The result of fertilization is the development of the ovule into the seed. By the segmentation of the fertilized egg, now invested by cell-membrane, the embryo-plant arises. A varying number of transverse segment-walls transform it into a pro-embryo—a cellular row of which the cell nearest the micropyle becomes attached to the apex of the embryo-sac, and thus fixes the position of the developing embryo, while the terminal cell is projected into its cavity. In Dicotyledons the shoot of the embryo is wholly derived from the terminal cell of the pro-embryo, from the next cell the root arises, and the remaining ones form the suspensor. In many Monocotyledons the terminal cell forms the cotyledonary portion alone of the shoot of the embryo, its axial part and the root being derived from the adjacent cell; the cotyledon is thus a terminal structure and the apex of the primary stem a lateral one—a condition in marked contrast with that of the Dicotyledons. In some Monocotyledons, however, the cotyledon is not really terminal. The primary root of the embryo in all Angiosperms points towards the micropyle. The developing embryo at the end of the suspensor grows out to a varying extent into the forming endosperm, from which by surface absorption it derives good material for growth; at the same time the suspensor plays a direct part as a carrier of nutrition, and may even develop, where perhaps no endosperm is formed, special absorptive "suspensor roots" which invest the developing embryo, or pass out into the body and coats of the ovule, or even into the placenta. In some cases the embryo or the embryo-sac sends out suckers into the nucellus and ovular integument. As the embryo develops it may absorb all the food material available, and store, either in its cotyledons or in its hypocotyl, what is not immediately required for growth, as reserve-food for use in germination, and by so doing it increases in size until it may fill entirely the embryo-sac; or its absorptive power at this stage may be limited to what is necessary for growth and it remains of relatively small size, occupying but a small area of the embryo-sac, which is otherwise filled with endosperm in which the reserve-food is stored. There are also intermediate states. The position of the embryo in relation to the endosperm varies, sometimes it is internal, sometimes external, but the significance of this has not yet been established. The formation of endosperm starts, as has been stated, from the endosperm nucleus. Its segmentation always begins before that of the egg, and thus there is timely preparation for the nursing of the young embryo. If in its extension to contain the new formations within it the embryo-sac remains narrow, endosperm formation proceeds upon the lines of a cell-division, but in wide embryo-sacs the endosperm is first of all formed as a layer of naked cells around the wall of the sac, and only gradually acquires a pluricellular character, forming a tissue filling the sac. The function of the endosperm is primarily that of nourishing the embryo, and its basal position in the embryo-sac places it favourably for the absorption of food material entering the ovule. Its duration varies with the precocity of the embryo. It may be wholly absorbed by the progressive growth of the embryo within the embryo-sac, or it may persist as a definite and more or less conspicuous constituent of the seed. When it persists as a massive element of the seed its nutritive function is usually apparent, for there is accumulated within its cells reserve-food, and according to the dominant substance it is starchy, oily, or rich in cellulose, mucilage or proteid. In cases where the embryo has stored reserve food within itself and thus provided for self-nutrition, such endosperm as remains in the seed may take on other functions, for instance, that of water-absorption. Some deviations from the usual course of development may be noted. Parthenogenesis, or the development of an embryo from an egg-cell without the latter having been fertilized, has been described in species of Thalictrum, Antennaria and Alchemilla. Polyembryony is generally associated with the development of cells other than the egg-cell. Thus in Erythronium and Limnocharis the fertilized egg may form a mass of tissue on which several embryos are produced. Isolated cases show that any of the cells within the embryo-sac may exceptionally form an embryo, e.g. the synergidae in species of Mimosa, Iris and Allium, and in the last-mentioned the antipodal cells also. In Coelebogyne (Euphorbiaceae) and in Funkia (Liliaceae) polyembryony results from an adventitious production of embryos from the cells of the nucellus around the top of the embryo-sac. In a species of Allium, embryos have been found developing in the same individual from the egg-cell, synergids, antipodal cells and cells of the nucellus. In two Malayan species of Balanophora, the embryo is developed from a cell of the endosperm, which is formed from the upper polar nucleus only, the egg apparatus becoming disorganized. The last-mentioned case has been regarded as representing an apogamous development of the sporophyte from the gametophyte comparable to the cases of apogamy described in Ferns. But the great diversity of these abnormal cases as shown in the examples cited above suggests the use of great caution in formulating definite morphological theories upon them.

Fruit and seed

As the development of embryo and endosperm proceeds within the embryo-sac, its wall enlarges and commonly absorbs the substance of the nucellus (which is likewise enlarging) to near its outer limit, and combines with it and the integument to form the seed-coat; or the whole nucellus and even the integument may be absorbed. In some plants the nucellus is not thus absorbed, but itself becomes a seat of deposit of reserve-food constituting the perisperm which may coexist with endosperm, as in the water-lily order, or may alone form a food-reserve for the embryo, as in Canna. Endospermic food-reserve has evident advantages over perispermic, and the latter is comparatively rarely found and only in non-progressive series. Seeds in which endosperm or perisperm or both exist are commonly called albuminous or endospermic, those in which neither is found are termed exalbuminous or exendospermic. These terms, extensively used by systematists, only refer, however, to the grosser features of the seed, and indicate the more or less evident occurrence of a food-reserve; many so-called exalbuminous seeds show to microscopic examination a distinct endosperm which may have other than a nutritive function. The presence or absence of endosperm, its relative amount when present, and the position of the embryo within it, are valuable characters for the distinction of orders and groups of orders. Meanwhile the ovary wall has developed to form the fruit or pericarp, the structure of which is closely associated with the manner of distribution of the seed. Frequently the influence of fertilization is felt beyond the ovary, and other parts of the flower take part in the formation of the fruit, as the floral receptacle in the apple, strawberry and others. The character of the seed-coat bears a definite relation to that of the fruit. Their function is the twofold one of protecting the embryo and of aiding in dissemination; they may also directly promote germination. If the fruit is a dehiscent one and the seed is therefore soon exposed, the seed-coat has to provide for the protection of the embryo and may also have to secure dissemination. On the other hand, indehiscent fruits discharge these functions for the embryo, and the seed-coat is only slightly developed.

Economic importance

Flowering plants provide a very high percentage of the base food for human use, whether directly or through livestock feed. Of all the families of flowering plants, the Poaceae, or grass family, is by far the most important, providing the bulk of all feedstocks (rice, corn (maize), wheat, barley, rye, oats, millet, sugar cane, sorghum), with the Fabaceae, or legume family, in second place. Also of high importance are the Solanaceae, or nightshade family (potatoes, tomatoes, and peppers, among others), the Cucurbitaceae, or gourd family (also including pumpkins and melons), the Brassicaceae, or mustard family (including rapeseed and cabbage), and the Apiaceae, or parsley family. Many of our fruits come from the Rutaceae, or rue family, and the Rosaceae (rose family, including apples, pears, cherries, apricots, plums, etc). In some parts of the world, certain single species assume paramount importance because of their variety of uses. An example is the coconut (Cocos nucifera) on Pacific atolls. Another example is the olive (Olea europaea) in the Mediterranean. Flowering plants also provide economic resources in the form of wood, paper, fiber (cotton, flax, and hemp, among others), medicines (digitalis, camphor), decorative and landscaping plants, and many, many other uses.

References and external links

- Angiosperm Phylogeny Group (2003). An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG II. Botanical Journal of the Linnean Society 141: 399-436. [http://www.blackwell-synergy.com/links/doi/10.1046/j.1095-8339.2003.t01-1-00158.x/full/ Available online].
- [http://tolweb.org/tree?group=Angiosperms&contgroup=Spermatopsida Angiosperms] – Tree of Life Web Project
- Cronquist, Arthur. (1981) An Integrated System of Classification of Flowering Plants. Columbia Univ. Press, New York.
- [http://www.news.harvard.edu/gazette/1999/12.16/angiosperms.html Oldest Known Flowering Plants Identified By Genes], William J. Cromie, Harvard Gazette, December 16, 1999.
- Stevens, P.F. (2001 onwards). [http://www.mobot.org/MOBOT/Research/APweb/welcome.html Angiosperm Phylogeny Website] at Missouri Botanical Garden.
- [http://delta-intkey.com/angio/ L. Watson and M.J. Dallwitz (1992 onwards). The families of flowering plants: descriptions, illustrations, identification, information retrieval.] http://delta-intkey.com Category:Magnoliophyta sort31 Angiospermae sort31 Angiospermae Category:Sexuality Category:Pollination ko:속씨식물 ms:Angiosperm ja:被子植物門 th:ไม้ดอก

Rutaceae

see text Rutaceae is a family of plants of the order Sapindales. Species of the family generally have flowers that divide into four or five parts, usually with strong scents. They range in form and size from herbs to shrubs and small trees. The most economically important genus in the family is Citrus, which includes the Orange, Lemon, Lime and Grapefruit.

Genera

There are about 160 genera, including:
- Achronychia - Lemon Aspen, et al
- Adenandra
- Agathosma
- Aegle - Bael
- Amyris - West Indian Sandalwood
- Boronia
- Bosistoa - Bonewoods
- Chloroxylon - Ceylon Satinwood
- Choisya - Mexican orange
- Citropsis - African orange cherry
- Citrus - Citrus
- Dictamnus - Burning-bush
- Flindersia - Crow Ash, Cudgerie
- Fortunella - Kumquat
- Geijera - Wilga, Axebreakers
- Melicope - Corkwood, Alani
- Murraya - Curry tree
- Phellodendron - Cork-tree
- Poncirus - Trifoliate orange
- Ptelea - Hoptree
- Ruta - Rue
- Skimmia - Skimmia
- Tetradium (Euodia) - Euodia
- Zanthoxylum - Toothache tree Category:Sapindales ko:운향과 ja:ミカン科