Taraxacum ()
Like other members of the family Asteraceae, they have very small flowers collected together into a composite flower head. Each single flower in a head is called a floret. In part due to their abundance, along with being a generalist species, dandelions are one of the most vital early spring nectar sources for a wide host of pollinators.
Etymology
The Latin name
Taraxacum derives from the
Arabic tarakhshaqūn, meaning "bitter herb".
[Gledhill, David (2008). The Names of Plants. Cambridge University Press. (hardback), (paperback). pp 279, 371] The Arabic term is possibly of
Persian language origin.
Persian polymath Al-Razi used the word tarakhshaqūn in relation to dandelions, chicory, and endives.
Al-Razi wrote "the tarakhshaqūn is like chicory, but more efficacious"; it is unclear exactly to which plant Al-Razi referred however.
If Persian in origin, the word could have originally meant "bitter
purslane" from تلک (talk, 'bitter') and چکش (chakūk, 'purslane').
Gerard of Cremona, in translating Arabic to Latin around 1170, spelled it
tarasacon.
[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 طرشقون tarashaqun is derivable in turn from Persian تلخ چکوک talkh chakok, bitter herb ( Downloadable at Archive.org).]
The English name, dandelion, is a borrowing of the French dent de lion[S. Potter & L. Sargent (1973) Pedigree: essays on the etymology of words from nature. Collins New Naturalist series Volume 56] 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;
Description
Taraxacum species are
taproot,
perennial plant,
herbaceous plants, native to
temperate areas of the Northern Hemisphere. The genus contains many species, which usually (or in the case of
triploids, obligately) reproduce by
apomixis, resulting in many local populations and
endemism. In the
British Isles alone, 234
species complex (i.e. morphologically distinct clonal populations) are recognised in nine loosely defined sections.
A number of
Taraxacum species can act as
, pioneer species that rapidly colonise disturbed soil. The
common dandelion (
T. officinale) has been introduced over much of the temperate world, and it is especially effective at spreading along roads, cemeteries, lawns, and pastures.
A week or two after flowering, the dandelion's flower becomes a round seed head.
The
, specialized leaves around the flower, curve backwards. The parachute ball fully opens into a sphere,
and the yellow petals fall away.
When development is complete, the mature seeds are attached to white, fluffy "parachutes", which easily detach from the seed head and glide on the wind, dispersing.
In general, the leaves are long or longer, simple, lobed-to-pinnatisect, forming a basal rosette above the central taproot. The range from yellow to orange, and they are open in the daytime, but closed at night. The heads are attached to a hollow stem (scape) that is usually leafless and rises or more above the ground.
The seeds are able to cover large distances when dispersed due to the unique morphology of the pappus, which works to create a unique type of vortex ring that stays attached to the seed rather than being sent downstream.
Similar plants
Many plants in the family
Asteraceae with yellow flowers are sometimes known as
. In the case of
Hypochaeris (
Hypochaeris), both plants carry similar flowers, which form into windborne seeds. However, dandelion have unbranched, hairless and leafless, hollow stems, while cat's ear 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, whereas those of
cat's ear are hairy.
Early-flowering dandelions may be distinguished from coltsfoot (
Tussilago farfara) by their basal rosette of leaves, their lack of disc florets, and the absence of scales on the flowering stem.
Other plants with superficially similar flowers include
(
Hieracium) and
crepis (
Crepis). These are distinguished by branched stems, which are usually hairy and bear leaves.
Classification
The genus is taxonomically complex due to the presence of
apomixis; any morphologically distinct clonal population would deserve its own
microspecies. About 235
apomixis and
polyploid microspecies have been recorded in Great Britain and Ireland alone.
Phylogenetic approaches are also complicated by the accelerated mutation in apomixic lines and repeated ancient hybridisation events in the genus.
[
]
By 1970, the group was divided into about 34 macrospecies or sections, and about 2000 microspecies;
Botanists specialising in the genus Taraxacum are sometimes called taraxacologists,
Selected species
-
Taraxacum albidum, the white-flowered Japanese dandelion, a hybrid between T. coreanum and T. japonicum
-
Taraxacum algarbiense
-
Taraxacum aphrogenes, the Paphos dandelion
-
Taraxacum arcticum
-
Taraxacum balticum
-
Taraxacum brachyceras
-
Taraxacum brevicorniculatum, frequently misidentified as T. kok-saghyz and a poor rubber producer
-
Taraxacum californicum, the California dandelion, an endangered species
-
Taraxacum carneocoloratum
-
Taraxacum centrasiaticum, the Xinjiang dandelion
-
Taraxacum ceratophorum, the horned dandelion, considered by some sources to be a North American subspecies of T. officinale ( T. officinale subsp. ceratophorum)
-
Taraxacum coreanum
-
Taraxacum desertorum
-
Taraxacum erythrospermum, the red-seeded dandelion, often considered a variety of T. laevigatum (i.e., T. laevigatum var. erythrospermum)
-
Taraxacum farinosum, the Turkish dandelion
-
Taraxacum holmboei, the Troödos dandelion
-
Taraxacum hybernum
-
Taraxacum japonicum, the Japanese dandelion, no ring of smallish, downward-turned leaves under the flower head
-
Taraxacum kok-saghyz, the Kazakh dandelion, which produces rubber
-
Taraxacum laevigatum, the rock dandelion, achenes reddish brown and leaves deeply cut throughout the length, inner bracts' tips are hooded
-
Taraxacum lissocarpum
-
Taraxacum minimum
-
Taraxacum mirabile
-
Taraxacum officinale (syn. T. officinale subsp. vulgare), the common dandelion, found in many forms
-
Taraxacum pankhurstianum, the St. Kilda dandelion
-
Taraxacum platycarpum, the Korean dandelion
-
Taraxacum pseudoroseum
-
Taraxacum rubifolium
-
Taraxacum suecicum
Cultivars
-
'Amélioré à Coeur Plein' yields an abundant crop with minimal ground space because its leaves clump rather than spreading out.
-
'Broad-leaved' - The leaves are thick and tender. It grows up to 60 mm (2') wide depending on the soil.
-
'Vert de Montmagny' is a large-leaved, vigorous grower, which matures early.
History
Dandelions are thought to have evolved about 30 million years ago in Eurasia.[The Pliocene flora of Kholmech, southeastern Belarus and its correlation with other Pliocene floras of Europe by Felix Yu. VELICHKEVICH and Ewa ZASTAWNIAK - Acta Palaeobot. 43(2): 137–259, 2003] Dandelions have been used by humans for food and as a herb for much of recorded history. They were well known to ancient Egyptians, Greeks and Romans, and are recorded to have been used in traditional Chinese medicine for over a thousand years. The plant was used as food and medicine by Native Americans.
Ecology
Food for wildlife
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.
Seeds
Taraxacum seeds are an important food source for certain birds (linnets, Linaria spp.).
Nectar
Szabo studied nectar secretion in a dandelion patch over two years ( in 1981 and 1982). He measured average nectar volume at 7.4 μl/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.
Leaves
Insects eat the leaves of dandelions, especially species of Lepidoptera, which includes butterfly and . A study in Kargil, India, found that the most frequent insect visitors to dandelions were butterflies followed by species of hymenoptera and diptera.
As invasive species
Dandelions can cause significant economic damage as an invasive species and infestation of other crops worldwide;[ Non native species National Park Service] and hosts an annual "Dandelion Demolition" event where volunteers are trained to remove the plant from the park's roadsides.[Love, Colleen Coulon Denali's Dandelion Demolition returns after 2020 hiatus KTNA, June 17, 2021]
Cultivation
In food
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.
Dandelions contain bitter but water-soluble . The bitterness increases later in the season, after the flowers bloom, and as the leaves mature. To make dandelion greens more palatable, they can be blanched, picked young, served with other strong flavours, or some combination. In the Southern United States, they are traditionally served with a hot bacon dressing (similar to spinach salad).
The flower , along with other ingredients, usually including citrus, are used to make dandelion wine. Its ground, roasted roots can be used as Dandelion coffee.
Dye
The yellow flowers can be dried and ground into a yellow-pigmented powder and used as a dye.
Allergies
Dandelions may cause allergy for sensitive individuals when consumed or coming into contact with skin, but the risk is mild.
Herbalism
Dandelion has been used in traditional medicine in Europe, North America, and China.
Benefits to gardeners
With a wide range of uses, the dandelion is cultivated in small gardens to massive farms. It is kept as a companion plant; its taproot brings up nutrients for shallow-rooting plants. It is also known to attract pollinating insects and release ethylene gas, which helps fruit to ripen.
Cultural importance
It has been a Western tradition for someone to blow out a dandelion seed head and think of a wish they want to come true.
Five dandelion flowers are the emblem of White Sulphur Springs, West Virginia.
The dandelion is the official flower of the University of Rochester in New York State, and "Dandelion Yellow" is one of the school's official colours. "The Dandelion Yellow" is an official University of Rochester song.
Inspiration for engineering
Because dandelion seeds can travel great distances on the wind, they have been studied as a basis for passive flight technologies.[ In 2018, researchers discovered how dandelion seeds create a separated vortex ring, a type of airflow. The geometry of their pappus affects fluid behaviours around the seed in a way that the researchers could duplicate in microfabricated silicone discs.][ In 2022, researchers at the University 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.]
As a source of natural rubber
Dandelions secrete latex 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 optimisation techniques, scientists in the Fraunhofer 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 the natural rubber from rubber trees.
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