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 colored, 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 sap (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 "clocks" containing many single-seeded fruits called achenes. Each achene is attached to apappus of fine hairs, which enable wind-aided dispersal over long distances.

Dandelion is a winter perennial. The dandelion has thick fleshy tap root which often branches. New plants come from the root and root segments. Leaves form in a rosette, are deeply lobed, with the lobes pointing toward the base. Both the leaves and flower stems contain a white milky fluid.