I nominate the pansy to be the emblematic flower of Christianity. It comes in all sorts of colors and varieties, representing the diversity of the Christian family.
It's not an expensive flower, representing the free gift of grace.
The word 'pansy' is frequently used as a derogatory term much like "Christian" was (and sometimes is even now).
But honestly and truly, the reason it should represent Christianity is that it does not give up. My family has not planted pansies for years yet we find them hiding throughout the flowerbeds and yard. Yes, a single pansy is easy enough to pull up and dispose of, much like the individual Christian martyr is; but, as a whole, the Christian faith and the Church will live on through oppression, violence and slander just like the pansies continue to pop up where they can find the sunlight and the nourishment . And when Christianity is at its best, it will endure all sorts of things without resorting to violence to "protect" itself, its honor, its Scripture, or its leaders.
God help us if the pansies fight back.