Everything about Dandelion totally explained
The common name
Dandelion is given to members of the
genus Taraxacum, a large genus of
flowering plants in the family
Asteraceae. In the Asteraceae (formerly Compositae) the "flowers" are
morphologically a composite
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
asexually by
apomixis, where the seeds are produced without
pollination, resulting in offspring that are genetically identical to the parent plant.
Description
Dandelions are
tap-rooted biennial or
perennial herbaceous plants, native to
temperate areas of the
Northern Hemisphere of the
Old World. They are commonly known as weeds or
ruderals. The genus is
taxonomically very complex, with numerous macrospecies, and
polyploidy is also common; over 250
apomictic microspecies have been recorded in the
British Isles alone (Richards 1972). Some botanists take a much narrower view and only accept a total of about 60 species.
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
flower head, which is open in the daytime but closes at night, is borne singly on a hollow stem (scape) which rises 4–30 cm above the leaves and exudes a milky
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
florets.
The flower head matures into a spherical "clock" (also known as a "wishie") containing many single-seeded fruits (
achenes). Each achene is attached to a
pappus of fine hairs, which enable wind-aided dispersal over long distances.
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.
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
Dandelions evolved about thirty million years ago in Eurasia
(External Link
).
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 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 dente di leone,
Spanish diente de león,
Portuguese dente-de-leão,
Norwegian Løvetann, and
German Löwenzahn.
In modern
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 it's known as the
meacamas. Also, in the dialect of Veneto, Italy, it's known as
pisacan, which translates to "dog pisses", referring to how common they're found at the side of pavements (source: Giulia Zanetti, native of Veneto), and in the dialect of Novara, Italy, it's 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 it's called "dmuchawiec" which comes from "dmuchać", "to blow".
In
Turkish the dandelion is called
karahindiba meaning "black endive".
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).
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 it's called 'voikukka' ("butter flower") referring to its buttery colour. In
Swedish it's called 'maskros' ("worm rose"), likely referring to its low status (being mostly considered a weed) despite a fairly pleasant appearance.
Seeds
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 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's 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
As previously mentioned, the taxonomical situation of the genus is quite complex, mainly because many dandelions are genetically
triploid. An odd number of
chromosomes usually is associated with
sterility, but dandelions with this
karyotype can reproduce without
fertilization, by a process called
apomixis. In these individuals
flowers are inefficient
vestigial structures, although they may still produce a small percentage of fertile
pollen, keeping some genetic contact with sexual individuals.
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 isn't 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
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
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 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
eggs. The leaves are high in
vitamin A,
vitamin C and
iron, carrying more iron and
calcium than
spinach.
Dandelion flowers can be used to make dandelion
wine, for which there are many recipes. 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" 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; the milk is also applied to warts, helping get rid of them without damaging the surrounding skin.
Yellow or green dye colours can be obtained from the flowers but little colour can be obtained from the roots of the plant.
Antioxidant properties
Dandelion contains luteolin, an
antioxidant, and has demonstrated antioxidant properties without
cytotoxicity.
Caffeic acid and carcinogenicity
Caffeic acid is a secondary plant metabolite produced in dandelion,
yarrow,
horsetail and
whitethorn. Despite its name, it's unrelated to
caffeine. Recent studies have revealed this acid may be
carcinogenic. Caffeic acid was tested for carcinogenicity by oral administration in mice, it produced renal cell
adenomas in females, and a high incidence of renal tubular cell
hyperplasia in animals of each sex. However, more recent research shows that
bacteria present in the rodents' intestines may alter the formation of
metabolites of caffeic acid. There have been no known ill-effects of caffeic acid in humans.
Bees
Dandelions are important plants for bees. Not only is their used as an indicator that the honey bee season is starting, but they're also an important source of nectar and pollen early in the season.
False 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 both readily distinguished by their branched flowering stems which are usually hairy and bear leaves.
Selected species
References and external links
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.
Making Dandelions Palatable by John Kallas of Wild Food Adventures
~ at Wikibooks
Dandelion Syrup - step-by-step illustrated recipe in English
How to Get Rid of Dandelions
How to Grow Dandelions
Dandelion Poetry, Folklore, Literature, and Pictures
Dandelion at Plants For A Future
a university of Wisconsin article on dandelions
Further Information
Get more info on 'Dandelion'.
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