i'm not sure about this... however, according to one website: http://www.differencebetween.info/difference-between-tree-and-plant
"Trees differ from other plants in the Kingdom because of their trunk, which earns them the name of a perennial plant. From the thick stem, more stems rise on which there are leaves. ... In short, trees and plants have a lot more in common than difference."
Wanting to enter this challenge as well, I did a check and flora simply means any plant life in a particular region. :-) So a lovely entry for the challenge.
This is lovely. Really nice job with the lighting here.