Tanacetum

thumb|right|Tanacetum corymbosum

Tanacetum is a genus of about 160 species of flowering plants in the aster family, Asteraceae, native to many regions of the Northern Hemisphere. They are known commonly as tansies. The name tansy can refer specifically to Tanacetum vulgare, which may be called the common tansy or garden tansy for clarity. The generic name Tanacetum means 'immortality' in Botanical Latin, since tansy was once placed between the burial sheets of the dead to repel vermin.