Taraxacum

Taraxacum Temporal range: Miocene–recent 16.2–0 Ma[1] PreꞒ Ꞓ O S D C P T J K Pg N
A dandelion flower head composed of numerous small florets (top). The seedhead is shown below it.
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Asterids
Order:	Asterales
Family:	Asteraceae
Subfamily:	Cichorioideae
Tribe:	Cichorieae
Subtribe:	Crepidinae
Genus:	Taraxacum F. H. Wigg.
Type species
Taraxacum officinale[2] F. H. Wigg.
Species
See text
Synonyms
List Caramanica Tineo Eriopus D.Don Lasiopus D.Don Neo-taraxacum Y.R.Ling & X.D.Sun Wendelboa Soest

Taraxacum (/təˈræksəkəm/)^[3] 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.^[4] The genus is native to Eurasia 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 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 are edible in their entirety^[a] and have a long history of consumption.^[7] The common name dandelion (/ˈdændəlaɪ.ən/ DAN-də-ly-ən; from French dent-de-lion 'lion's tooth', referring to the jagged leaves) is also given to specific members of the genus.^[8]

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.^[9] 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.^[10]

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^[5] 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^[11] or clocks (in both British and American English)^{[12][13][14][15]} containing many single-seeded fruits called cypselae, similar to achenes. Each cypsela is attached to a pappus of fine hair-like material which enables anemochorous (wind-aided) dispersal over long distances.^{[citation needed]}

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.^[16]

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