Achillea millefolium, commonly known as yarrow or common yarrow, is a flowering plant in the family Asteraceae. Growing to 1 metre tall, it is characterized by small whitish flowers, a tall stem of fernlike leaves, and a pungent odor.

The family Asteraceae, with the original name Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae were first described in the year 1740. The number of species in Asteraceae is rivaled only by the Orchidaceae, and which is the larger family is unclear as the quantity of extant species in each family is unknown.