All flowers have a meaning. In the Victorian era, people used flowers as symbols to express their feelings.
Each of the books of the Svatura Series is titled for a flower which is appropriate to that book. The meanings of each of those flowers is:
watchfulness, faithfulness, I’ll always be true
dedicated to Apollo, loveliness, sorrow
a warning, change, betrayal, passion, the heart, emotions
magnificence, love, beauty, refinement, reflection, great power and absolute authority