Tansy

At a glance I assumed ‘tanacita’ meant something along the lines of “tenacity”, but looking into it, it actually stems from the Ancient Greek ‘athanasia’, meaning “immortality” or “undying”.

The name ultimately derives from the Greek "athanasia" meaning "immortality".

Tansy is a plant with many medicinal uses (a lot of which have now been discredited). It's well known for causing miscarriages in high doses, leading to its use as an abortifacient in the Middle Ages.