Dandelion is a herbacious perennial native to Europe and Asia and naturalized throughout the temperate regions of the world. The plant has a long taproot, which is dark brown on the outside and white on the inside, and dark-green, jagged-edged leaves (the source of the plant's name, derived from the French dent de lion, or lion's tooth), 5 to 30 centimeters in length. Dandelion has a bright yellow flower, roughly 3 to 5 centimeters in diameter, which opens during the day and closes in the evening. The flower sits atop a smooth, hollow stem which protrudes from the center of the leaves. Eventually, the flower gives way to form a fluffy, round seed head containing as many as 200 wispy seeds, which are spread by wind.
Dandelion root contains bitter principles known as sesquiterpene lactones, along with triterpenes, phytosterols, and flavonoids. The leaves are rich in beta-catotene and also contain moderate amounts of vitamin C, iron, magnesium, and zinc.
Dosage recommendations for dandelion vary widely. A common recommendation is 1 tablespoon of dried whole herb with 1 cup of water (as an infusion). Dandelion leaves and flowers are commonly consumed as food and are not associated with any toxicity. Large doses of dandelion root may cause stomach upset in some cases. Dandelion has been known to cause allergic skin reactions in some individuals.