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 Africa, Asia, and Europe, and have been widely introduced elsewhere. Many Taraxacum species produce seeds asexually so that seeds can be produced without pollination that are genetically identical to the parent plant
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 is 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.