Dandelion
57181
225959998
2008-07-16T05:36:41Z
Hardyplants
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[[WP:UNDO|Undid]] revision 225954077 by [[Special:Contributions/24.8.142.100|24.8.142.100]] ([[User talk:24.8.142.100|talk]])
{{otheruses}}
{{Cleanup|date=July 2007}}
{{Taxobox
| name = Dandelion
| image = Macro dandelion Fcb981.JPG
| image_width = 250px
| image_caption = A flowering dandelion.
| regnum = [[Plant]]ae
| divisio = [[Flowering plant|Magnoliophyta]]
| classis = [[Dicotyledon|Magnoliopsida]]
| ordo = [[Asterales]]
| familia = [[Asteraceae]]
| tribus = [[Cichorieae]]
| genus = '''''Taraxacum'''''
| genus_authority = [[Alexandre Henri Gabriel de Cassini|Cass.]]
| subdivision_ranks = Species
| subdivision = See text
}}
The common name '''Dandelion''' is given to members of the [[genus]] '''''Taraxacum''''', a large genus of [[flowering plant]]s in the family [[Asteraceae]]. In the Asteraceae (formerly Compositae) the "flowers" are [[Morphology (biology)|morphologically]] a composite [[Head (botany)|flower head]] consisting of many tiny flowers called florets. Dandelions are native to Europe and Asia and have been widely introduced elsewhere. Many ''Taraxacum'' species produce seeds [[asexual]]ly by [[apomixis]], where the seeds are produced without [[pollination]], resulting in offspring that are genetically identical to the parent plant.<ref>[http://128.104.239.6/uw_weeds/extension/articles/dandelion.htm Dandelion - J. Doll and T. Trower<!-- Bot generated title -->]</ref>
==Description==
[[Image:Taraxacum seed 1.jpg|left|250px|thumb|A dandelion clock.]]
[[Image:HalfSeeded-Dandelion.jpg|left|250px|thumb|A half seeded dandelion clock.]]
'''Dandelions''' are [[taproot|tap-rooted]] [[Biennial plant|biennial]] or [[perennial plant|perennial]] [[herbaceous]] plants, native to [[temperate]] areas of the [[Northern Hemisphere]] of the [[Old World]]. They are commonly known as weeds or [[ruderal]]s. The genus is [[taxonomy|taxonomically]] complex, with some [[botanist]]s dividing the group into numerous macrospecies, and many more microspecies: approximately 235 [[apomixis|apomictic]] and [[polyploid]] microspecies have been recorded in [[Great Britain]] and [[Ireland]]<ref>{{cite book | title = Dandelions of Great Britain and Ireland (Handbooks for Field Identification) | id = ISBN 978-0901158253 | pages = 330 | last = Richards | first = A.J. | date=1997 | publisher = BSBI Publications}}</ref>. Some botanists take a much narrower view and only accept a total of about 60 species.<ref>http://www.jstor.org/pss/2430530</ref>
The leaves are 5–25 cm long, simple and basal, entire or lobed, forming a rosette above the central taproot. As the leaves grow outward they push down the surrounding vegetation, such as grass in a lawn, which kills those plants by cutting off their access to sunlight. A bright yellow [[inflorescence|flower head]], which is open in the daytime but closes at night, is borne singly on a hollow stem (scape) which rises 4–75 cm<ref>http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=250067706</ref> above the leaves and exudes a milky [[Sap (plant)|sap]] ([[latex]]) when broken. A rosette may produce several flowering stems at a time. The flower head is 2–5 cm in diameter and consists entirely of ray [[floret]]s.
The flower head matures into a spherical "clock" (also known as a "wishie") containing many single-seeded fruits ([[achene]]s). Each achene is attached to a [[pappus (flower structure)|pappus]] of fine hairs, which enable wind-aided dispersal over long distances.
Dandelions are used as food plants by the [[larva]]e of some species of [[Lepidoptera]] ([[butterflies]] and [[moths]]). See [[List of Lepidoptera that feed on dandelions]].
[[Image:Taraxacum.jpg|right|250px|thumb|A dandelion flower head.]]
[[Image:Top view of a dandelion.JPG|250px|thumb|right|Top view of a dandelion head.]]
Away from their native regions, dandelions have become established in the [[Americas]], [[Australia]], and [[New Zealand]], and are now common throughout all temperate regions.
==History==
{{Expand|date=May 2008}}
Dandelions evolved about thirty million years ago in Eurasia<ref>[http://gardening.wsu.edu/column/05-04-03.htm Gardening in Western Washington: Dandelions]</ref>
They have been used by humans for food and herbalism for much of recorded history.
===Origin of the name===
The English name ''dandelion'' is a corruption of the French ''dent de lion''<ref>S. Potter & L. Sargent (1973) Pedigree: essays on the etymology of words from nature. Collins New Naturalist series Volume 56</ref> meaning [[lion]]'s tooth, referring to the coarsely-toothed leaves. The names of the plant have the same meaning in several other European languages, such as [[Italian language|Italian]] ''dente di leone'', [[Spanish language|Spanish]] ''diente de león'', [[Portuguese language| Portuguese]] ''dente-de-leão'', [[Norwegian language|Norwegian]] ''Løvetann'', and [[German language|German]] ''Löwenzahn''.
<br>In modern [[French language|French]] the plant is named ''pissenlit,'' which means "urinate in bed", apparently referring to its [[diuretic]] properties. Likewise, "pissabeds" is an English folkname for this plant, ''piscialletto'' in Italian and in [[Spanish language|Spanish]] it is known as the ''meacamas''. Also, in the dialect of Veneto, Italy, it is known as ''pisacan'', which translates to "dog pisses", referring to how common they are found at the side of pavements (source: Giulia Zanetti, native of Veneto), and in the dialect of Novara, Italy, it is known as ''soffione'', which translates to "blowing", and refers to the habit of blowing the seeds from the stalk (source: Silvia Paracchini, native of Novara). Likewise, in [[Polish language|Polish]] it is called "dmuchawiec" which comes from "dmuchać", "to blow" when in its seed state. Whilst in flower form the Poles know it as "Mlecz" a word derived from milk due to its milky sap.
<br>In [[Turkish language|Turkish]] the dandelion is called ''karahindiba'' meaning "black endive".
<br>[[Hungarian language|Hungarian]] names are ''kutyatej'' ("dog milk", referring to the white sap found in the stem) and ''gyermekláncfű'' ("child's chain grass", referring to the habit of children to pick dandelions, remove the flowers, and make links out of the stems by "plugging" the narrow top end of the stem into the wider bottom end).
<br>[[Lithuanian language|Lithuanian]] name ''kiaulpienė'' can be translated as "sow ''[[Sonchus]]''" (because plant ''Sonchus'' that has white sap also in Lithuanian is ''pienė'' (from ''pienas'' "milk)) or "sow milk".
In [[Finnish language|Finnish]] it is called 'voikukka' ("butter flower") referring to its buttery colour. In [[Swedish language|Swedish]] it is called 'maskros' ("worm rose"), likely referring to its low status (being mostly considered a weed) despite a fairly pleasant appearance.<br>
In [[Dutch language|Dutch]] it is called ''paardebloem'', meaning "horse-flower".
==Seeds==
[[Image:Dandelion Microscopic 2.jpg|thumb|250px|right|A microscopic view of a [[pappus (flower structure)|pappus]] from a dandelion clock.]]
The flower head is surrounded by [[bract]]s (sometimes mistakenly called [[sepal]]s) in two series. The inner [[bract]]s are erect until the seeds mature, then flex down to allow the seeds to disperse; the outer bracts are always reflexed downward. Some species drop the "parachute" (called a ''pappus'', modified sepals) from the achenes. Between the pappus and the achene, there is a stalk called a beak, which elongates as the fruit matures. The beak breaks off from the achene quite easily.
After pollination, the dandelion flower dries out for about 1-2 days and then the seed-bearing parachutes expand and lift out of the dried flower head. The dried part of the flower drops off and the parachute ball opens into a full sphere. The parachute drops off when the seed strikes an obstacle. Often dandelions can be observed growing in a crevice near a wall, because the blowing fruits hit the wall and the feathery pappi drop off, sending the dandelion seeds to the base of the obstacle where they germinate. After the seed is released, the parachutes lose their feathered structure and take on a fuzzy, cotton-like appearance, often called "dandelion snow."
While it was probably not developed evolutionarily, Dandelions seeds are often dispersed by young children, who often blow on or kick the clock.
==Seed development and genetics==
[[Image:Dandelion Microscopic 1.jpg|thumb|250px|left|A microscopic view of a dandelion clock showing the [[pericarp]] and the [[achene]]s.]]
As previously mentioned, the taxonomical situation of the genus is quite complex, mainly because many dandelions are genetically [[polyploidy|triploid]]. An odd number of [[chromosomes]] usually is associated with [[infertility|sterility]], but dandelions with this [[karyotype]] can reproduce without [[fertilization]], by a process called [[apomixis]].<ref>http://fieldcrop.msu.edu/documents/GR03-050.pdf</ref> In these individuals [[flower]]s are inefficient [[vestigial]] structures, although they may still produce a small percentage of fertile [[pollen]], keeping some genetic contact with sexual individuals. [[Diploid#Diploid|Diploid]] dandelions develop seeds after cross-[[pollination]] and are [[outcrossing]], or self-incompatible. In most zones of southern [[Europe]] and [[Asia]], dandelion populations are sexual or mixed sexual-apomictic, while in northern countries only triploid and [[tetraploid]] apomicts are present, as is in the zones where it is not native. This seems to be linked to higher temperatures, survival of pre-glacial populations and human impact, but the subject is still being studied.
There are usually 54 to 172 seeds produced per head, but a single plant can produce more than 2000 seeds a year. It has been estimated that more than 97 000 000 seeds/[[hectare]] could be produced every year by a dense stand of dandelions.
==Uses==
[[Image:Dandelion Blackwell 0136.jpg|thumb|250px|right|The dandelion's [[taproot]], on left in this drawing, makes this plant very difficult to uproot; the top of the plant breaks away, but the root stays in the ground and can sprout again.]]
{{seealso|Medicinal properties of dandelion}}
While the dandelion is considered a [[weed]] by most gardeners and lawn owners, the plant does have several [[culinary]] uses, and the specific name ''officinalis'' refers to its value as a [[herb|medicinal herb]]. Dandelions are grown commercially on a small scale as a [[leaf vegetable]]. The leaves (called dandelion greens) can be eaten cooked or raw in various forms, such as in [[soup]] or [[salad]]. They are probably closest in character to [[Mustard plant|mustard]] greens. Usually the young leaves and unopened buds are eaten raw in salads, while older leaves are cooked. Raw leaves have a slightly bitter taste. Dandelion salad is often accompanied with hard boiled [[egg (food)|egg]]s. The leaves are high in [[vitamin A]], [[vitamin C]] and [[iron]], carrying more iron and [[calcium]] than [[spinach]].<ref>[http://www.wildmanstevebrill.com/Plants.Folder/Dandelion.html Common Dandelion]</ref>
Dandelion flowers can be used to make dandelion [[wine]], for which there are many recipes.<ref>[http://winemaking.jackkeller.net/dandelion.asp winemaking: Dandelion Wines<!-- Bot generated title -->]</ref> It has also been used in a [[saison]] [[ale]] called Pissenlit (literally "wet the bed" in French) made by [[Brasserie Fantôme]] in [[Belgium]]. Another recipe using the plant is dandelion flower jam. Ground roasted dandelion root can be used as a [[coffee]] substitute.
Dandelion root is a registered drug in [[Canada]], sold principally as a [[diuretic]]. A leaf [[decoction]] can be drunk to "purify the blood", for the treatment of anemia, jaundice, and also for nervousness. Drunk before meals, dandelion root coffee is claimed to stimulate digestive functions and function as a liver tonic. "[[Dandelion and burdock|Dandelion and Burdock]]" is a soft drink that has long been popular in the [[United Kingdom]] with authentic recipes sold by health food shops. It is unclear whether cheaper supermarket versions actually contain extracts of either plant.
The milky latex has been used as a mosquito repellent;<ref>[http://plantwatch.sunsite.ualberta.ca/plants/com_dan.php Plantwatch - Plants<!-- Bot generated title -->]</ref>the milk has also been used to treat warts, as a folk remedy.<ref name=NHM>[http://www.nhm.ac.uk/nature-online/life/plants-fungi/country-cures/exhibit_dandelion.html Dandelion - The Natural History Museum - Country Cures<!-- Bot generated title -->]</ref>
Yellow or green dye colours can be obtained from the flowers but little colour can be obtained from the roots of the plant.<ref>A. Dyer (1976) Dyes from natural sources. G. Bell & Sons Ltd., London</ref>
[[Image:P1000091.JPG|thumb|left|250px|A plate of sauteed dandelion greens, with [[Wehani rice]]]]
==Antioxidant properties==
Dandelion contains luteolin, an [[antioxidant]], and has demonstrated antioxidant properties without [[cytotoxicity]].<ref>Chun Hu and David D. Kitts. Food, Nutrition and Health, Faculty of Agricultural Sciences, University of British Columbia, Vancouver, BC, Canada. October 2004. Luteolin and luteolin-7-O-glucoside from dandelion flower suppress iNOS and COX-2 in RAW264.7 cells. Springer Netherlands. '''245''':1-2(107-113). </ref><ref>[http://www.springerlink.com/content/qg16p71737602150/ Luteolin and luteolin-7-O-glucoside from dandelion flower suppress iNOS and COX-2 in RAW264.7 cells]</ref>
==Caffeic acid and carcinogenicity==
[[Caffeic acid]] is a secondary plant metabolite produced in dandelion, [[yarrow]], [[horsetail]] and [[whitethorn]]. Despite its name, it is unrelated to [[caffeine]]. Recent studies have revealed this acid may be [[carcinogenic]]. When caffeic acid was tested for carcinogenicity by oral administration in mice, renal cell [[adenoma]]s appeared in females, and a high incidence of renal tubular cell [[hyperplasia]] occurred in animals of each sex.<ref>''Caffeic acid phenethyl ester is a potent and specific inhibitor of activation of nuclear transcription factor NF-kappa B.'', Natarajan K, Singh S, Burke TR Jr, Grunberger D, Aggarwal BB., Proc. Natl. Acad. Sci. U S A., 1996 Aug 20;93(17):9090-5.</ref> However, more recent research shows that [[bacteria]] present in the rodents' intestines may alter the formation of [[metabolite]]s of caffeic acid.<ref>[http://www.pnas.org/cgi/content/abstract/69/6/1413 Caffeic Acid Metabolism by Gnotobiotic Rats and their Intestinal Bacteria]</ref><ref>[http://jn.nutrition.org/cgi/content/full/133/6/1853 Chlorogenic Acid Bioavailability Largely Depends on Its Metabolism by the Gut Microflora in Rats]</ref> There have been no known ill effects of caffeic acid in humans.
==Bees==
Dandelions are important plants for bees. Not only is their {{phenology|flowering}} used as an indicator that the honey bee season is starting,{{Fact|date=May 2008}} but they are also an important source of nectar and pollen early in the season.{{Fact|date=April 2008}}
==False dandelions==
[[Image:Photos-photos 1088103921 Floating.jpg|thumb|250px|right|[[Macro photography|Macro]] photo of dandelion seed dispersal.]]
Dandelions are so similar to [[catsear]]s (''Hypochaeris'') that catsears are also known as "false dandelions." Both plants carry similar flowers which form into windborne seeds. However, dandelion flowers are borne singly on unbranched, hairless and leafless, hollow stems, while catsear flowering stems are branched, solid and carry bracts. Both plants have a basal rosette of leaves and a central taproot. However, the leaves of dandelions are smooth or glabrous, whereas those of catsears are coarsely hairy.
Other plants with superficially similar flowers include [[hawkweed]]s (''Hieracium'') and [[crepis|hawksbeard]]s (''Crepis''). These are both readily distinguished by their branched flowering stems which are usually hairy and bear leaves.
==Selected species==
* ''[[Taraxacum albidum]]'', a white-flowering [[Japan]]ese dandelion.
* ''[[Taraxacum californicum]]'', the endangered California dandelion
* ''[[Taraxacum officinale]]'' (syn. ''T. officinale subsp. vulgare''), Common Dandelion. Found in many forms.
* ''[[Taraxacum japonicum]]'', Japanese dandelion. No ring of smallish, downward-turned leaves under the flowerhead.
* ''[[Taraxacum laevigatum]]'' (syn. ''T. erythrospermum''), Red-seeded Dandelion; achenes reddish brown and leaves deeply cut throughout length. Inner bracts' tips are hooded.
==References==
{{reflist}}
==External links==
{{commonscat|Taraxacum}}
* {{Cite book |last=Everitt |first=J.H. |coauthors=Lonard, R.L., Little, C.R. |title=Weeds in South Texas and Northern Mexico |publisher=Texas Tech University Press |location=Lubbock |year=2007}} ISBN 0-89672-614-2
* Richards, A. J. 1972. The ''Taraxacum'' flora of the British Isles. ''Watsonia'' 9 (supplement): 1-141.
* Gail, Peter. ''The Dandelion Celebration: A Guide to Unexpected Cuisine''. Cleveland, Ohio: Goosefoot Acres Press, 1994. ISBN 1-879863-51-0.
*[http://www.backwoodshome.com/articles2/kallas82.html Making Dandelions Palatable by John Kallas of Wild Food Adventures]
*[[b:Transwiki:How to cook dandelions|How to cook dandelions]] ~ at ''Wikibooks''
*[http://fxcuisine.com/default.asp?Display=78 Dandelion Syrup - step-by-step illustrated recipe in English]
*[http://landscaping.about.com/od/weedsdiseases/a/kill_dandelions.htm How to Get Rid of Dandelions]
*[http://sankey.ws/dandelion.html How to Grow Dandelions]
*[http://www.pfaf.org/database/plants.php?Taraxacum+officinale&CAN=WIKIPEDIA Dandelion at Plants For A Future]
*[http://ipcm.wisc.edu/uw_weeds/extension/articles/dandelion.htm a university of Wisconsin article on dandelions]
*[http://www.science.tv/watch/136124592c8d4825a06f/Dandelion-(Taraxacum)-Opening-Timelapse Timelapse video of dandelions opening]
*{{cite web|title=SpringerLink|work=Chun Hu and David D. Kitts. Food, Nutrition and Health, Faculty of Agricultural Sciences, University of British Columbia, Vancouver, BC, Canada. October 2004. Luteolin and luteolin-7-O-glucoside from dandelion flower suppress iNOS and COX-2 in RAW264.7 cells. Springer Netherlands. '''245''':1-2(107-113)
|url=http://www.springerlink.com/content/qg16p71737602150/}}
==See also==
* [[List of beneficial weeds]]
* [[List of companion plants]]
[[Category:Taraxacum]]
[[Category:Herbs]]
[[Category:Invasive plant species]]
[[Category:Leaf vegetables]]
[[Category:Lawn weeds]]
[[Category:Medicinal plants]]
[[Category:Flora of Greenland]]
[[bg:Глухарче]]
[[da:Mælkebøtte]]
[[de:Löwenzahn (Taraxacum)]]
[[et:Võilill]]
[[es:Taraxacum]]
[[eo:Leontodo]]
[[fa:قاصدک]]
[[fr:Pissenlit]]
[[ko:민들레속]]
[[hsb:Mlóč (ród)]]
[[hr:Maslačak]]
[[id:Randa Tapak]]
[[os:Къаппа-къуппа]]
[[ka:ბაბუაწვერა]]
[[lt:Kiaulpienė]]
[[hu:Gyermekláncfű]]
[[ja:タンポポ]]
[[no:Løvetanner]]
[[nn:Løvetann]]
[[pl:Mniszek (roślina)]]
[[pt:Dente-de-leão]]
[[ru:Одуванчик]]
[[sco:Dentylion]]
[[simple:Dandelion]]
[[sl:Regrat]]
[[sr:Маслачак]]
[[fi:Voikukka]]
[[sv:Maskrosor]]
[[vi:Bồ công anh]]
[[tr:Taraxacum]]
[[zh:蒲公英]]