The dandelion (Taraxacum officinale) has been used in herbalism since ancient times. The highest concentration of the plant's active ingredients can be found in its roots.
Some of the most important active ingredients found in the dandelion are the bitter sesquiterpene lactones. Sesquiterpene lactones, sometimes acting as plant hormones, are used by the dandelion to defend itself against predators and are highly bioactive.