Tansy, or Bitter Buttons, a perennial herb. It is native to Europe and is a common roadside weed throughout most of the United States. The plant grows to about three feet (90 cm) in height. It has fernlike leaves and tiny, yellow flowers arranged in button-shaped clusters. The tansy has a strong scent. Because the leaves contain aromatic oils, they are occasionally used to flavor such foods as puddings. Extracted tansy oil is occasionally used as a medication.
The tansy is Tanacetum vulgare of the composite family, Compositae.