Dandelion 🌻 Taraxacum
🌿 Dent-de-Lion 🌿
A dandelion flower head, often mistaken for a single flower, is actually a composite of many tiny florets (small individual flowers).
These florets are arranged in a way that creates the appearance of a single, large, yellow "petal". After the flower blooms and is pollinated, the florets develop into seeds, each attached to a fuzzy pappus that helps them disperse on the wind, forming the familiar "dandelion clock"
These florets are arranged in a way that creates the appearance of a single, large, yellow "petal". After the flower blooms and is pollinated, the florets develop into seeds, each attached to a fuzzy pappus that helps them disperse on the wind, forming the familiar "dandelion clock"
Taraxacum is a large genus of flowering plants in the family Asteraceae, which consists of species commonly known as dandelions. The scientific and hobby study of the genus is known as taraxacology. The genus is native to Eurasia and North America, but the two most commonplace species worldwide, T. officinale (the common dandelion) and T. erythrospermum (the red-seeded dandelion), were introduced from Europe into North America, where they now propagate as wildflowers. Both species are edible in their entirety. The common name dandelion from French dent-de-lion 'lion's tooth') is also given to specific members of the genus.
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. 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.
In general, the leaves are 50–250 mm (2–10 in) long or longer, simple, lobed-to-pinnatisect, and form a basal rosette above the central taproot. The flower 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 10–100 mm (3⁄8–3+7⁄8 in) or more above the leaves. Stems and leaves exude a white, milky latex when broken. A rosette may produce several flowering stems at a time. The flower heads are 20–50 mm (3⁄4–2 in) in diameter and consist entirely of ray florets. The flower heads mature into spherical seed heads sometimes called blowballs or clocks (in both British and American English) containing many single-seeded fruits called achenes. Each achene is attached to a pappus of fine hair-like material which enables 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 often
reflexed downward, but remain appressed in plants of the sections Palustria and Spectabilia.
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.Taraxacum officinale. For similar plants, see False dandelion.
Plusieurs hypothèses se proposent d'expliquer l'origine du nom scientifique de la plante. Taraxacum provient peut-être du grec ancien τάραξις / táraxis, qui désignait une inflammation de l'œil et akeomai,
« guérir », le latex du pissenlit passant en effet pour calmer les
irritations oculaires. En raison de sa consommation dans des salades,
certains auteurs considèrent que ce nom est une corruption arabe du mot
grec trogemon signifiant comestible. À moins qu'il ne provienne plus directement de l'arabe tharakhchakon, qui désignait une plante semblable au pissenlit commun. Le nom générique Taraxacum trouve en effet son origine dans les écrits médiévaux perses en pharmacie. Vers 900, le savant perse Al-Razi écrit « le tarashaquq est comme la chicorée ». Vers l’an 1000, le savant persan Avicenne écrit tout un chapitre de livre sur le Taraxacum. L'écrivain Gérard de Crémone vers 1170 fait une traduction de l'arabe au latin : le terme tarashaquq est alors orthographié en « tarasacon ».
Le genre Leontodon (du grec leontodon, en latin dens Leonis, littéralement « dent de lion », allusion aux dents aiguës de ses feuilles) tel que défini initialement par Linné comprenait le basionyme Leontodon taraxacum. Mais c'est le lectotype Taraxacum officinale (Wigg) qui a servi à désigner le genre.
A dandelion flower head composed of numerous small florets (top). The seedhead is shown below it.
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