From the experts:
Tansy is a flower name rarer than Rose, livelier than Lily and a lot less teasable than Pansy.
Tansy is a perennial herbaceous plant of the aster family that has clusters of small bright yellow blossoms. It was cultivated by the ancients for medicinal purposes, and has found a variety of other uses over the ages, associated with health and immortality.
There have been a couple of eponymous novels titled Tansy, and it was the name of a character on Hart of Dixie,