Iris in my garden. The Iris flower earned its name from the ancient Greek Goddess Iris, a messenger to the gods who was thought to use the rainbow as a bridge between heaven and earth. By some accounts, the ancient Greeks believed the rainbow was actually the flowing, multi-coloured robes of Iris. Others believed the beautiful multi-coloured flowers were also part of her robe or the flowing veil from her dress. Thus, these flowers were named to honor the Rainbow Goddess and bring favor upon the earth.