It does great at being a reference book. Beautiful pictures and creative bouquets at the end. Some historical context to the flower's meaning and place in history without getting bogged down in too many details (ie no growing guides or anything like that). 

It feels weird to give it 5 stars when it's usually what I'd rate a novel that was a page turner, but I really can't think of how to improve it short of adding more flowers to it. The index by meaning in particular is a highlight!