Tansy (Tanacetum vulgare) is a perennial, herbaceous flowering plant of the aster family, native to temperate Europe and Asia. It has been introduced to other parts of the world, including North America, and in some areas has become invasive. It is also known as common tansy, bitter buttons, cow bitter, or golden buttons.

The scent is similar to that of camphor with hints of rosemary. The leaves and flowers are toxic if consumed in large quantities.

This hardy, sun-loving plant is resistant to cold and frost and commonly grows in open areas close to water, such as roadsides and ditches.