I knew a kid named Tilia, after the tree; I always thought it was quite pretty.
I like a lot of the name ideas listed here - Liriope is wonderful, Lycaste, Silene, Honesty, Caspia, Begonia, Ilima, and Calliandra especially. Jarrah is really nice too, its growing on me in leaps and bounds.
I've always thought Astilbe would be a fun flower name for a person. My favourite flower, canna lily, doesn't lend itself well to being a name sadly.
To choose from your list, I might go with Begonia
Cleo. It's wacky, and the flowers are nice and lush, just my kinda thing. Begonia also works in Spain, where it is actually used somewhat frequently (as
Begoña), so that works well!