Tansy n. : Any plant of the composite genus Tanacetum. The common tansy (T. vulgare) has finely divided leaves, a strong aromatic odor, and a very bitter taste. It is used for medicinal and culinary purposes.

Tansy n. : A dish common in the seventeenth century, made of eggs, sugar, rose water, cream, and the juice of herbs, baked with butter in a shallow dish.

Example:
How long until I can let horses in field after Tansy has been removed?

Taxonomy
tansy, tansy ragwort, tansy beetle, Tanacetum vulgare, History, insect, herb, New York, plants, unranked, leaf, Flora, thujone, volatile oils, Weeds, free encyclopedia, intestinal worms, The leaves.

Defination from the web:
Tansy, Bitter Buttons, Cow Bitter, Mugwort, or Golden Buttons. ... Tansy is a flowering herbaceous plant with finely divided compound leaves and yellow, buttonlike flowers. ... Common tansy was used as a face wash and was reported to lighten and purify the skin. ...