Is it ensure, insure, or assure?
the flowering plant Myosotis palustris, 1530s, from Old French ne m'oubliez mye; in 15c. the flower was supposed to ensure that those wearing it should never be forgotten by their lovers. Similar loan-translations took the name into other languages, cf. German Vergißmeinnicht, Swedish forgätmigej, Hungarian nefelejcs, Czech nezabudka.