Taraxacum (/təˈræksəkəm/)[3] is a largegenus offlowering plants in the familyAsteraceae, which consists of species commonly known asdandelions. The scientific and hobby study of the genus is known as taraxacology.[4] The genus is native to Eurasia but the two most commonplace species worldwide,T. officinale (the common dandelion) andT. erythrospermum (the red-seeded dandelion), were introduced from Europe into North America, where they are an invasive species.[5] Dandelions thrive in temperate regions and can be found in yards, gardens, sides of roads, among crops, and in many other habitats.[6] Both species areedible in their entirety[a] and have a long history of consumption.[7] The common namedandelion (/ˈdændəlaɪ.ən/DAN-də-ly-ən; from Frenchdent-de-lion'lion's tooth', referring to the jagged leaves) is also given to specific members of thegenus.[8]
Like other members of the family Asteraceae, they have very small flowers collected together into a compositeflower head. Each single flower in a head is called afloret. In part due to their abundance, along with being ageneralist species, dandelions are one of the most vital early springnectar sources for a wide host ofpollinators.[9] ManyTaraxacum species produce seedsasexually byapomixis, where the seeds are produced withoutpollination, resulting in offspring that are genetically identical to the parent plant.[10]
In general, the leaves are 5–25 centimetres (2.0–9.8 in) long or longer, simple, lobed-to-pinnatisect, and form a basalrosette above the central taproot. Theflower heads are yellow to orange coloured, and are open in the daytime, but closed at night. The heads are borne singly on a hollow stem (scape) that is usually leafless and rises 1–10 centimetres (0.4–3.9 in) or more[5] above the leaves. Stems and leaves exude a white, milkylatex when broken. A rosette may produce several flowering stems at a time. The flower heads are 2–5 centimetres (0.8–2.0 in) in diameter and consist entirely of rayflorets. The flower heads mature into spherical seed heads sometimes calledblowballs[11] orclocks (in both British and American English)[12][13][14][15] containing many single-seeded fruits calledcypselae, similar toachenes. Each cypsela is attached to apappus of fine hair-like material which enablesanemochorous (wind-aided) dispersal over long distances.[16]
The flower head is surrounded bybracts (sometimes mistakenly calledsepals) in two series. The inner bracts are erect until the seeds mature, then flex downward to allow the seeds to disperse. The outer bracts are often reflexed downward, but remain appressed in plants of the sectionsPalustria andSpectabilia. Between the pappus and the achene is a stalk called a beak, which elongates as the fruit matures. The beak breaks off from the achene quite easily, separating the seed from the parachute.[17]
These are individualpollen grains of the dandelion -Taraxacum officinale.Segment ofpappus fiber showing barbs
The species ofTaraxacum aretap-rooted,perennial,herbaceous plants, native totemperate areas of the Northern Hemisphere. The genus contains many species, which usually (or in the case oftriploids, obligately) reproduce byapomixis, resulting in many local populations andendemism. In the British Isles alone, 234microspecies (i.e. morphologically distinct clonal populations) are recognised in nine loosely defined sections, of which 40 are "probably endemic".[18] A number of species ofTaraxacum are seed-dispersedruderals that rapidly colonize disturbed soil, especially the common dandelion (T. officinale), which has been introduced over much of the temperate world. After flowering is finished, the dandelion flower head dries out for a day or two. The dried petals and stamens drop off, the bracts reflex (curve backwards), and the parachute ball opens into a full sphere. When development is complete, the mature seeds are attached to white, fluffy "parachutes" which easily detach from the seedhead and glide by wind, dispersing.
The seeds are able to cover large distances when dispersed due to the unique morphology of thepappus which works to create a unique type ofvortex ring[19][20] that stays attached to the seed rather than being sent downstream. In addition to the creation of this vortex ring, the pappus can adjust its morphology depending on the moisture in the air. This allows the plume of seeds to close up and reduce the chance to separate from the stem, waiting for optimal conditions that will maximize dispersal and germination.[21][22]
The pappus of a dandelion seed, which aids in wind-driven dispersalField with flowering dandelions,Tatarstan, Russia
Hawksbeard flower heads and ripe seeds are sometimes confused with dandelions.ATaraxacum officinale seedhead with only one seed still attached
Many similar plants in the familyAsteraceae with yellow flowers are sometimes known asfalse dandelions. Dandelion flowers are very similar to those of cat's ears (Hypochaeris). Both plants carry similar flowers, which form into windborne seeds. However, dandelion flowers are borne singly on unbranched, hairless and leafless, hollow stems, while cat's ear 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 cat's ears are coarsely hairy.[18]: 740
Early-flowering dandelions may be distinguished fromcoltsfoot (Tussilago farfara) by their basal rosette of leaves, their lack of disc florets, and the absence of scales on the flowering stem.[23]
Other plants with superficially similar flowers includehawkweeds (Hieracium) andhawksbeards (Crepis). These are readily distinguished by branched flowering stems, which are usually hairy and bear leaves.[18]: 740
The genus istaxonomically complex due to the presence of apomixis: any morphologically distinct clonal population would deserve its ownmicrospecies. Phylogenetic approaches are also complicated by the accelerated mutation in apomixic lines and repeated ancient hybridization events in the genus.[24]
As of 1970, the group is divided into about 34 macrospecies orsections, and about 2000microspecies;[25] some botanists take a much narrower view and only accept a total of about 60 (macro)species.[25] By 2015, the number has been revised to include 60 sections and about 2800 microspecies. 30 of these sections are known to reproduce sexually.[24]
About 235apomictic andpolyploid microspecies have been recorded in Great Britain and Ireland alone.[26]
Taraxacum ceratophorum, the horned dandelion, considered by some sources to be a North American subspecies ofT. officinale (T. officinale subsp.ceratophorum)[30]
'Amélioré à Coeur Plein' yields an abundant crop without taking up much ground, and tends toblanch itself naturally, due to its clumping growth habit.
'Broad-leaved' - The leaves are thick and tender and easily blanched. In rich soils, they can be up to 60 mm (2') wide. Plants do not go to seed as quickly as French types.
'Vert de Montmagny' is a large-leaved, vigorous grower, which matures early.[33]
Dandelions are thought to have evolved about 30 million years ago inEurasia.[34]Fossil seeds ofTaraxacum tanaiticum have been recorded from thePliocene of southernBelarus.[35] Dandelions have been used by humans for food and as anherb for much of recorded history. They were well known to ancient Egyptians, Greeks and Romans, and are recorded to have been used intraditional Chinese medicine for over a thousand years. The plant was used as food and medicine byNative Americans.[36] Dandelions were probably brought to North America on theMayflower for their supposed medicinal benefits.[37] Purposeful cultivation of dandelions seems to have begun in the United States in the early mid-19th century.[38]
Leaf resemblance to the teeth of a lion (French:dent-de-lion)
The Latin nameTaraxacum originates inmedieval Arabic writings on pharmacy. The scientistAl-Razi around 900 CE wrote "the tarashaquq is like chicory".[citation needed] The scientist and philosopherIbn Sīnā around 1000 CE wrote a book chapter onTaraxacum.[citation needed]Gerard of Cremona, in translating Arabic to Latin around 1170, spelled ittarasacon.[39]
The English name, dandelion, is a borrowing of the Frenchdent de lion[40][41] meaning "lion's tooth", referring to the coarsely toothed leaves. The plant is also known as blowball, cankerwort, doon-head-clock, witch's gowan, milk witch, lion's-tooth, yellow-gowan, Irish daisy, monks-head, priest's-crown, and puff-ball;[42] other common names includefaceclock,pee-a-bed,wet-a-bed,[43]swine's snout,[44][45] white endive, and wild endive.[46]
The English folk name "piss-a-bed" (and indeed the equivalent Frenchpissenlit) refers to the strongdiuretic effect of the plant's roots.[47] In various northeastern Italian dialects, the plant is known aspisacan ("dog pisses"), because they are found at the side of pavements.[48][unreliable source?] InSwedish, it is calledmaskros (worm rose) after the nymphs of small insects (thrips larvae) usually present in the flowers.[49]
Taraxalisin, a serineproteinase, is found in thelatex of dandelion roots.[53][54] Maximal activity of the proteinase in the roots is attained in April, at the beginning of plant development after the winter period.[54] Each dandelion seed has a mass(weight) of 500 micrograms or 0.0005g (1/125 of a grain).[citation needed]
The entire plant, including the leaves, stems, flowers, and roots, is edible and rich in nutrients such as calcium, iron, and vitamins A and K.[55] Dandelions grow wild on every continent except Antarctica. Most commercial varieties are native toEurasia. It is aperennial plant with ataproot, so the greens can be repeatedly harvested if the root remains in the ground.[56]
Dandelion greens with roasted pork and peaches
Dandelions contain bitter but water-solublesesquiterpenes. The bitterness increases later in the season, after the flowers bloom, and as the leaves mature. To make dandelion greens more palatable, they can beblanched, picked young, served with other strong flavors, or some combination. In theSouthern United States, they are traditionally served with a hot bacon dressing (similar tospinach salad).[56][57] In Italy, the leaves aresauteed, added to soups, or added raw to salads.[58] Dandelion greens have been a part of traditionalKashmiri cuisine,Lebanese cuisine,[59]Spanish cuisine,Italian cuisine,Albanian cuisine,Slovenian,Sephardic Jewish,Chinese,Greek cuisine (χόρτα) andKorean cuisines. InCrete, the leaves of a variety called 'Mari' (Μαρί), 'Mariaki' (Μαριάκι), or 'Koproradiko' (Κοπροράδικο) are eaten by locals, either raw or boiled, in salads.T. megalorhizon, a species endemic to Crete, is eaten in the same way; it is found only at high altitudes (1,000–1,600 metres (3,300–5,200 ft)) and in fallow sites, and is calledpentaramia (πενταράμια) oragrioradiko (αγριοράδικο).[60]
Dandelions do not depend on wildlife for distribution or pollination; however much of wildlife benefits from the abundance of the plant. Rabbits, wild turkeys, white-tailed deer, eastern chipmunks, bobwhite quail, and many species of bird will consume the seeds and foliage. Additionally, many insects will collect nectar from the flower, especially in early spring when there are very few other flowers in bloom.[72]
Szabo studied nectar secretion in a dandelion patch over two years (59.2 and 8.9 flowers per square metre (5.50 and 0.83/sq ft) in 1981 and 1982). He measured average nectar volume at 7.4μl/flower in 1981 and 3.7 μl/flower in 1982. The flowers tended to open in the morning and close in the afternoon with the concentrations significantly higher on the second day.[74]
Dandelions can cause significant economic damage as aninvasive species and infestation of other crops worldwide;[74] in some jurisdictions, the speciesT. officinale is listed as anoxious weed.[74][75] It can also be considered invasive in protected areas such asnational parks. For example,Denali National Park and Preserve in Alaska listsTaraxacum officinale as the most common invasive species in the park[76] and hosts an annual "Dandelion Demolition" event where volunteers are trained to remove the plant from the park's roadsides.[77]
With a wide range of uses, the dandelion is cultivated in small gardens to massive farms. It is kept as acompanion plant; itstaproot brings up nutrients for shallow-rooting plants. It is also known to attractpollinatinginsects and releaseethylene gas, which helps fruit to ripen.[78]
The dandelion is the official flower of theUniversity of Rochester inNew York State, and "Dandelion Yellow" is one of the school's official colors. "The Dandelion Yellow" is an official University of Rochester song.[82]
The ability of dandelion seeds to travel as far as a kilometer in dry, windy and warm conditions, has been an inspiration for designing light-weight passive drones.
In 2018, researchers discovered that dandelion seeds have a separated vortex ring.[19] This work provided evidence that dandelion seeds have fluid behavior around fluid-immersed bodies that may help understand locomotion, weight reduction and particle retention in biological and man-made structures.
In 2022, researchers at theUniversity of Washington demonstrated battery-free wireless sensors and computers that mimic dandelion seeds and can float in the wind and disperse across a large area.[83]
Dandelions secretelatex when the tissues are cut or broken, yet in the wild type, the latex content is low and varies greatly.Taraxacum kok-saghyz, the Russian dandelion, is a species that produced industrially useful amounts during WW2. Using modern cultivation methods and optimization techniques, scientists in theFraunhofer Institute for Molecular Biology and Applied Ecology (IME) in Germany developed a cultivar of the Russian dandelion that is suitable for current commercial production of natural rubber. The latex produced exhibits the same quality as thenatural rubber fromrubber trees.[84] In collaboration withContinental AG, IME is building a pilot facility. As of May 2014[update], the first prototype test tires made with blends from dandelion-rubber are scheduled for testing on public roads over the next few years.[85] In December 2017, Linglong Group Co. Ltd., a Chinese company, invested $450 million into making commercially viable rubber from dandelions.[86]
^Loebach CA (2015).Investigating seed dispersal distances and long distance dispersal mechanisms of the invasive plant, Alliaria Petiolata. Illinois State University.ISBN9781321782141.OCLC988948576.
^Blamey M, Fitter R, Fitter A (2003).Wild flowers of Britain and Ireland: The Complete Guide to the British and Irish Flora. London: A & C Black. p. 274.ISBN978-1408179505.
^Dudman AA, Richards AJ, Stewart O (2000).Dandelions of Great Britain and Ireland. B.S.B.I. handbook (Reprinted with minor alterations 2000 ed.). London: Botanical Society of the British Isles.ISBN978-0-901158-25-3.
^ThePliocene flora of Kholmech, southeasternBelarus and its correlation with otherPliocene floras ofEurope by Felix Yu. VELICHKEVICH and Ewa ZASTAWNIAK - Acta Palaeobot. 43(2): 137–259, 2003
^Clarke, Charlotte Bringle (1977).Edible and useful plants of California. Berkeley: University of California Press. p. 191.ISBN978-0-520-03261-3.
^"Dandelions". Maine Organic Farmers and Gardeners Association. Archived fromthe original on 20 February 2017. Retrieved17 April 2017.
^Reported inAn Etymological Dictionary of the English Language, by Walter W. Skeat (1888) (Downloadable at Archive.org). InAn Etymology Dictionary of Modern English by Ernest Weekley (1921) it is reported that Arabic طرشقونtarashaqun is derivable in turn from Persian تلخ چکوکtalkh chakok, bitter herb (Downloadable at Archive.org).
^"Carotenoids". Micronutrient Information Center, Linus Pauling Institute, Oregon State University. 1 July 2016. Retrieved27 June 2019.
^Bogacheva AM, Rudenskaya GN, Preusser A, et al. (1999). "A new subtilisin-like proteinase from roots of the dandelion Taraxacum officinale Webb S. L".Biochemistry. Biokhimiia.64 (9):1030–7.PMID10521720.
^Huber M, Triebwasser-Freese D, Reichelt M, et al. (2015). "Identification, quantification, spatiotemporal distribution and genetic variation of major latex secondary metabolites in the common dandelion (Taraxacum officinale agg.)".Phytochemistry.115:89–98.Bibcode:2015PChem.115...89H.doi:10.1016/j.phytochem.2015.01.003.PMID25682510.
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