Taraxacum

"Dandelion" redirects here. It often refers specifically to Taraxacum officinale. For other uses, see Dandelion (disambiguation).
Dandelion
A dandelion flower head composed of hundreds of smaller florets (top) and seed head (bottom)
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Asterids
Order: Asterales
Family: Asteraceae
Tribe: Cichorieae
Genus: Taraxacum
Cass.
Species

See text

Taraxacum is a large genus of flowering plants in the family Asteraceae. They are native to Eurasia and North America, and two species, T. officinale and T. erythrospermum, are found as weeds worldwide.[1] Both species are edible in their entirety.[2] The common name dandelion (pronounced /ˈdændɨlaɪ.ən/, DAN-dih-lye-ən, from French dent-de-lion, meaning lion's tooth) is given to members of the genus, and like other members of the Asteraceae family, they have very small flowers collected together into a composite flower head. Each single flower in a head is called a floret. Many Taraxacum species produce seeds asexually by apomixis, where the seeds are produced without pollination, resulting in offspring that are genetically identical to the parent plant.[3]

Contents

Description

The species of Taraxacum are tap-rooted biennial or perennial herbaceous plants, native to temperate areas of the Old World.

The leaves are 5–25 cm long or longer, simple and basal, entire or lobed, forming a rosette above the central taproot. The flower heads are yellow to orange colored, and are open in the daytime but closed at night. The heads are borne singly on a hollow stem (scape) that rises 1–10 cm or more[4] above the leaves and exudes a milky sap (latex) when broken. A rosette may produce several flowering stems at a time. The flower heads are 2–5 cm in diameter and consists entirely of ray florets. The flower heads mature into a spherical "clocks"[5] containing many single-seeded fruits called achenes. Each achene is attached to a pappus of fine hairs, which enable wind-aided dispersal over long distances.

The flower head is surrounded by bracts (sometimes mistakenly called sepals) 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 always reflexed downward. Some species drop the "parachute" from the achenes; the hair-like parachutes are called pappus, and they are modified sepals. 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, separating the seed from the parachute.

Seed dispersal

A number of species of Taraxacum are seed dispersed ruderals 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. Finally, the seed-bearing parachutes expand and lift out of it. The parachute drops off the achene when it strikes an obstacle. After the seed is released, the parachutes lose their feathered structure and take on a fuzzy, cotton-like appearance, often called "dandelion snow".

False dandelions

Hawksbeard flower heads and ripe seeds are sometimes confused with Dandelions.

Dandelions are so similar to catsears (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 hawkweeds (Hieracium) and hawksbeards (Crepis). These are readily distinguished by branched flowering stems, which are usually hairy and bear leaves.

Classification

The genus is taxonomically complex, with some botanists dividing the group into about 34 macrospecies, and about 2000 microspecies;[6] approximately 235 apomictic and polyploid microspecies have been recorded in Great Britain and Ireland.[7] Some botanists take a much narrower view and only accept a total of about 60 species.[6]

Selected species

Cultivars

History

Dandelions are thought to have evolved about thirty million years ago in Eurasia;[11] they have been used by humans for food and as a herb for much of recorded history. They were introduced to North America by early European immigrants.

Origin of the names

The Latin name taraxacum has its origin in medieval Arabic writings on pharamacy. Al-Razi around 900 (A.D.) wrote "the tarashaquq is like chicory". Ibn Sīnā around 1000 (A.D.) wrote a book chapter on taraxacum. Gerard of Cremona, in translating Arabic to Latin around 1170, spelled it tarasacon.[12]

The English name dandelion is a corruption of the French dent de lion[13] 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 the Welsh dant y llew, Italian dente di leone, Catalan dent de lleó, Spanish diente de león, Portuguese dente-de-leão,Norwegian Løvetann, Danish Løvetand and German Löwenzahn.

In modern French the plant is named pissenlit, (or pisse au lit Fr vernacular).[14] Likewise, "piss-a-bed" is an English folk-name for this plant,[15] as is piscialletto in Italian and the Spanish meacamas. These names refer to the strong diuretic effect of the roots of the herb,[15] roasted or raw/fresh. In various north-eastern Italian dialects the plant is known as pisacan ("dog pisses"), referring to how common they are found at the side of pavements.[16]

In France it is also known as Laitue de Chien (Dog's lettuce); Salade de Taupe (Mole's salad or Brown salad), Florin d'Or (Golden florin); Cochet (Cockerel); Fausse Chicorée (False Chicory); Couronne de moine (Monk's crown); Baraban.[14]

In several European languages the plant, or at least its parachute ball stage, is named after the popular children's pastime of blowing the parachutes off the stalk: Pusteblume German for "blowing flower"), soffione (Italian for "blowing"; in some northern Italian dialects),[16] dmuchawiec (Polish, derived from the verb "blow"), одуванчик (Russian, derived from the verb "blow").

In other languages the plant is named after the white sap found in its stem, e.g. Mlecz (derived from the Polish word for "milk"), mælkebøtte (Danish for "milk pot") kutyatej (Hungarian for "dog milk"), маслачак (derived from the Serbian word маслац, meaning "butter"). Also the Lithuanian name kiaulpienė can be translated as "sow milk", and similarly, in Latvian it is called 'pienene, the word being derived from piens - milk .

The alternative Hungarian name gyermekláncfű ("child's chain grass"), refers 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. In Macedonian, it's called глуварче, stemming from the word глув, which means deaf, because of a traditional belief that says that if a dandelion parachute gets in your ear, you might become deaf. In Turkish the dandelion is called karahindiba meaning "black endive". While the root flesh is white colored, the outer skin of the root is dark brown or black. In Swedish, it is called maskros ("worm rose", named after the small insects (thrips) usually present in the flowers).[17] In Finnish and Estonian, it is called voikukka and võilill, respectively, meaning "butter flower", referring to its buttery colour. In Dutch it is called paardenbloem, meaning "horse-flower". In Chinese it is called pú gōng yīng (蒲公英), meaning flower that grows in public spaces by the riverside. In Japanese, it is tanpopo (タンポポ?).

Properties and Uses

Beneficial but often unappreciated weed

The dandelion plant is a beneficial weed, with a wide range of uses, and is even a good companion plant for gardening, but is often thought of solely as "bad". It has been described as "a plant for which we once knew the use but we've forgotten it".[18] Homeowners or hired lawn-keepers often control dandelions with herbicides, and counter-efforts against herbicide use can create social friction in residential neighborhoods.[19]

In fact, the plant is good protection for grasses and grains in areas prone to armyworms, and its ability to break up hard earth with its deep tap root, bringing up nutrients from below the reach of other plants, makes it a good companion for weaker or shallower-rooted crops, including tomato plants.

Culinary use

Dandelion leaves contain abundant amounts of vitamins and minerals, especially Vitamins A, C and K, and are good sources of calcium (0.19% net weight), potassium (0.4% net weight) and fair amounts of iron and manganese,[20] higher than similar leafy greens such as spinach. They contain 15% protein and 73% carbohydrates, 37% of which is fiber (27% of the leaves are fiber).[21] The leaves also contain smaller amounts of over two dozen other nutrients, and are a significant source of beta carotene (0.03% net weight), lutein and zeaxanthin (combined 0.066% net weight).[22] A cup of dandelion leaves contains 112% daily recommendation of vitamin A, 32% of vitamin C, and 535% of vitamin K and 218 mg potassium, 103 mg calcium, and 1.7 mg of iron. Dandelions are also an excellent source of vitamin H, which aids weight loss when ingested.

Dandelion flowers contain luteolin, an antioxidant, and have demonstrated antioxidant properties without cytotoxicity.[23][24]

Dandelion contains Caffeic acid, as a secondary plant metabolite, which some studies show to exhibit anticarcinogenic properties[25][26] at low doses but carcinogenic properties at high doses.[27] There have been no known ill effects of caffeic acid in humans.[28][29]

Dandelion leaves and buds have been a part of traditional Mediterranean (especially Sephardic [30][31][32]) and Asian, most notably Chinese and Korean cuisine.[33][34] In Crete, Greece, a variety called Mari (Μαρί), Mariaki (Μαριάκι) or Koproradiko (Κοπροράδικο), has its leaves eaten raw or boiled in salads by the locals. Another endemic species of Crete, which is found only at high altitudes (1000 to 1600 m.) and in fallow sites, called pentaramia (πενταράμια) or agrioradiko (αγριοράδικο) and which has been named Taraxacum megalorhizon by Prof. Michalis Damanakis of the Botanics Department of the University of Crete, has its leaves eaten raw or boiled in salads by the locals[35].

The flower petals, along with other ingredients, are used to make dandelion wine. The roasted, ground roots can be used as a caffeine-free dandelion coffee.

Medicinal uses

Dandelions, flowers, roots and leaves, have been used for centuries in traditional medicine & medicinal teas, most notably for liver detoxification, as a natural diuretic and for inflammation reduction. Unlike other diuretics, dandelion leaves contain potassium, a mineral that is often lost during increased urination. There is also evidence that this property of dandelion leaves may normalize blood sugar.[36]

Dandelion leaves are believed to have a diuretic effect as they increase salt and water excretion from the kidneys.[37]

Bees

Dandelions are important plants for northern hemisphere bees. Not only is their flowering used as an indicator that the honey bee season is starting, but they are also an important source of nectar and pollen early in the season.[38] Dandelion pollen is a common allergen and a common component in bee pollen.[39] This allergen may be commonly responsible for asthma, allergic rhinitis, allergic conjunctivitis and contact dermatitis in sensitive individuals.

Butterflies

Dandelions are used as food plants by the larvae of some species of Lepidoptera (butterflies and moths). See List of Lepidoptera that feed on dandelions. They are also used as a source of nectar by the Pearl-bordered Fritillary (Boloria euphrosyne), one of the earliest emerging butterflies in the spring.

Culture

Four dandelion flowers are the emblem of White Sulphur Springs, West Virginia.[40] The citizens celebrate spring with an annual Dandelion Festival.

The dandelion is the official flower of the University of Rochester and "Dandelion Yellow" is one of the school's official colors. The Dandelion Yellow is an official University of Rochester song.[41]

At the time of blooming, crowns are made from dandelions by some children and adults.[42]

See also

References

  1. ↑ "Taraxacum". Flora of North America. http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=132314. 
  2. ↑ "Wild About Dandelions". Mother Earth News. http://www.motherearthnews.com/Real-Food/2008-04-01/Dandelion-Recipes.aspx?page=2. 
  3. ↑ Dandelion - J. Doll and T. Trower
  4. ↑ Taraxacum in Flora of North America @ efloras.org
  5. ↑ "Dandelion Clock - Definition from Longman English Dictionary Online". Ldoceonline.com. http://www.ldoceonline.com/dictionary/dandelion-clock. Retrieved 2010-07-03. 
  6. ↑ 6.0 6.1 Richards, A.J. (1970). Eutriploid facultative agamospermy in Taraxacum. New Phytologist. 69(3): 761–774 plate.
  7. ↑ Richards, A.J. (1997). Dandelions of Great Britain and Ireland (Handbooks for Field Identification). BSBI Publications. p. 330. ISBN 978-0901158253. 
  8. ↑ "Plants for a future: Taraxacum kok-saghiz". http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Taraxacum+kok-saghyz. 
  9. ↑ Flora of North America
  10. ↑ Edible Plants
  11. ↑ Gardening in Western Washington: Dandelions
  12. ↑ Reported in An Etymological Dictionary of the English Language, by Walter W. Skeat (1888) (Downloadable at Archive.org). In An Etymology Dictionary of Modern English by Ernest Weekley (1921) it is reported that Arabic tarashaqun is derivable in turn from Persian talkh chakok, bitter herb (Downloadable at Archive.org).
  13. ↑ S. Potter & L. Sargent (1973) Pedigree: essays on the etymology of words from nature. Collins New Naturalist series Volume 56
  14. ↑ 14.0 14.1 French Wiki - Taraxacum
  15. ↑ 15.0 15.1 Taylor, Joseph (1819). Antiquitates curiosae: the etymology of many remarkable old sayings, proverbs and singular customs explained by Joseph Taylor (2nd ed.). T&J Allman. p. 97. http://books.google.com/?id=OveC_aPCuXcC&pg=PA100&dq=whitsun&cd=163#v=onepage&q=whitsun. Retrieved 25 May 2010. 
  16. ↑ 16.0 16.1 Anon. "Dandelion - far more than a weed". Frapez.com. Frapez soothie spa. http://www.frapez.com/content/brochures/Dandelion_brochure.pdf. Retrieved 30 May 2010. 
  17. ↑ "Den virtuella floran: Taraxacum F. H. Wigg. - Maskrosor" (in Swedish). Linnaeus.nrm.se. http://linnaeus.nrm.se/flora/di/astera/tarax/welcome.html. Retrieved 2010-07-03. 
  18. ↑ NJ.com
  19. ↑ "The Dandelion King" by Robert Wright, Opinionator blog, The New York Times, April 20, 2010, 8:39 pm. With 477 reader comments, and links to two organizations: "SafeLawns.org, run by Paul Tukey, who has been described as 'the godfather of organic lawn care'; and the National Coalition for Pesticide-Free Lawns (where 'pesticides' include both herbicides and insecticides)." Retrieved 2010-05-17.
  20. ↑ NutritionData.com
  21. ↑ Calorie count at About.com
  22. ↑ Healthyrecipes.com
  23. ↑ 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).
  24. ↑ Luteolin and luteolin-7-O-glucoside from dandelion flower suppress iNOS and COX-2 in RAW264.7 cells
  25. ↑ Huang MT, et al. Inhibitory effect of curcumin, chlorogenic acid, caffeic acid and ferulic acid on tumor promotion in mouse skin by 12-0-tetradecanoylphorbol-13-acetate. Cancer Research 1988; 48(21):5941-5946
  26. ↑ Lee WJ, Zhu BT Inhibition of DNA methylation by caffeic acid and chlorogenic acid, two common catechol-containing coffee polyphenols. Carcinogenesis 2006; 27(2):269-277.
  27. ↑ Eisenbrand, Gerhard (2000). Carcinogenic and anticarcinogenic factors in food: symposium. Weinheim: Wiley-VCH. p. 105. ISBN 978-3-527-27144-3. 
  28. ↑ Caffeic Acid Metabolism by Gnotobiotic Rats and their Intestinal Bacteria
  29. ↑ Chlorogenic Acid Bioavailability Largely Depends on Its Metabolism by the Gut Microflora in Rats
  30. ↑ In Mamas Kitchen
  31. ↑ Cookbooks - Ecookbooks.com
  32. ↑ Barnes & Noble
  33. ↑ Food in Korea
  34. ↑ Institut de l’Information Scientifique et Technique
  35. ↑ Kleonikos G. Stavridakis , Κλεόνικος Γ. Σταυριδάκης (2006). Wild edible plants of Crete - Η Άγρια βρώσιμη χλωρίδα της Κρήτης. Rethymnon Crete. ISBN 960-631-179-1. 
  36. ↑ The University of New Mexico
  37. ↑ University of Maryland, complimentary medicine
  38. ↑ Pellett, Frank Chapman (1920). American Honey Plants; Together With Those Which Are of Special Value to the Beekeeper as Sources of Pollen. American Bee Journal Publication. ISBN 1152862715. http://books.google.com/books?id=JpllAAAAMAAJ&q=dandelion+pollen+beekeeping&dq=dandelion+pollen+beekeeping&source=bl&ots=t4v9eoNX7L&sig=L8Rjq5BBGckAjq6-ev1qTW-Hvgo&hl=fr&ei=WOezS8jJDYH-8AbW6rX6AQ&sa=X&oi=book_result&ct=result&resnum=5&ved=0CB0Q6AEwBDgK#v=snippet&q=dandelion%20pollen%20beekeeping&f=false. Retrieved 2010-07-03. 
  39. ↑ Immunocapinvitrosight.com
  40. ↑ "Welcome to Main Street White Sulphur Springs...Make it home". Wssmainstreet.org. http://www.wssmainstreet.org/. Retrieved 2010-07-03. 
  41. ↑ "Songs of the University of Rochester". Lib.rochester.edu. 2010-01-14. http://www.lib.rochester.edu/index.cfm?PAGE=1816#dand. Retrieved 2010-07-03. 
  42. ↑ Making a dandelion crown with photos

External links