Back in the day, flowers had a certain symbolism. The forget-me-not is obviously a plea to be remembered. Roses mean love & passion, however a yellow rose can show jealousy and infidelity. Sunflowers that in nature follow the sun across the sky, mean infatuation or foolish passion. Poppies for remembrance.
The Iris however is associated with death. Iris was the Greek Goddess of the Rainbow and she used that rainbow to transport women's souls to the underworld and also to carry messages to earth from the Gods.