I think this is a great idea! I actually tried something like this once...only I went one step further and assigned each character a bird AND a flower. It got a little messy...but I enjoyed developing the artstyle, near the end. ^^;
One issue I ran into was in trying to use the 'Language of Flowers' for my character assignments-- I don't think there's an exhaustive/definitive list of all flower meanings, and even if there is, I don't think the website I was using met that standard. ^^; After a while I felt self-conscious about the accuracy of my characters' flowers, and re-conceptualized the story to make them less important...I could probably do better research now, but the story's so old and established, it's not really worth it. I think I'd rather just see someone else tackle the idea.