Taraxacum /təˈræksəkʉm/ is a large genus of flowering plants in the family Asteraceae. They are native to Eurasia and North and South America, and two species, T. officinale and T. erythrospermum, are found as weeds worldwide. Both species are edible in their entirety. The common name dandelion (/ˈdændɨlaɪ.ən/ dan-di-ly-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.
The species of Taraxacum are tap-rooted biennial or perennial herbaceous plants, native to temperate areas of the globe.
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 coloured, 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 above the leaves and exudes a milky latex when broken. A rosette may produce several flowering stems at a time. The flower heads are 2–5 cm in diameter and consist entirely of ray florets. The flower heads mature into spherical seed heads 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 hairs, which enable wind-aided dispersal over long distances.
Text courtesy Wikipedia.