text: It depends on your definition of a flower - the biggest flowering structure is the Titan Arum however they are really inflorences which means that they have many flowers inside the main flower (like dasys)http://www.botanic.cam.ac.uk/titan.htm the Largest is the Gient Rafflesia - this is the biggest single flower on earth and is one of the few total parisitetic plants - it lives in vine roots http://en.wikipedia.org/wiki/Rafflesia_arnoldii