Dandelions are thought to have evolved about 30 million years ago in Eurasia. Fossil seeds of Taraxacum tanaiticum have been recorded from the Pliocene of southern Russia. Dandelions have been used by humans for food and as an herb for much of recorded history. They were well known to ancient Egyptians, Greeks and Romans, and have been used in Chinese traditional medicine for over a thousand years. Dandelions probably arrived in North America on the Mayflower–not as stowaways, but brought on purpose for their medicinal benefits.

Taraxacum (/təˈræksəkʊm/) is a large genus of flowering plants in the family Asteraceae which consists of species commonly known as dandelion. They are native to Eurasia and North America, but the two commonplace species worldwide, T. officinale and T. erythrospermum, were introduced from Europe and now propagate as wildflowers. Both species are edible in their entirety. The common name dandelion (/ˈdændɪlaɪ.ən/ DAN-di-ly-ən, from French dent-de-lion, meaning “lion’s tooth”) is given to members of the genus. 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.

Dandelions are found on all continents and have been gathered for food since prehistory, but the varieties cultivated for consumption are mainly native to Eurasia. A perennial plant, its leaves will grow back if the taproot is left intact. To make leaves more palatable, they are often blanched to remove bitterness, or sautéed in the same way as spinach. Dandelion leaves and buds have been a part of traditional Kashmiri, Slovenian, Sephardic, Chinese, and Korean cuisines. In Crete, the leaves of a variety called ‘Mari’ (Μαρί), ‘Mariaki’ (Μαριάκι), or ‘Koproradiko’ (Κοπροράδικο) are eaten by locals, either raw or boiled, in salads. T. megalorhizon, a species endemic to Crete, is eaten in the same way; it is found only at high altitudes (1000 to 1600 m) and in fallow sites, and is called pentaramia (πενταράμια) or agrioradiko (αγριοράδικο).

The flower petals, along with other ingredients, usually including citrus, are used to make dandelion wine. The ground, roasted roots can be used as a caffeine-free dandelion coffee. Dandelion was also traditionally used to make the traditional British soft drink dandelion and burdock, and is one of the ingredients of root beer. Also, dandelions were once delicacies eaten by the Victorian gentry, mostly in salads and sandwiches.

Dandelion leaves contain abundant vitamins and minerals, especially vitamins A, C, and K, and are good sources of calcium, potassium, iron, and manganese.

Historically, dandelion was prized for a variety of medicinal properties, and it contains a number of pharmacologically active compounds. Dandelion is used as a herbal remedy in Europe, North America, and China. It has been used in herbal medicine to treat infections, bile and liver problems, and as a diuretic.