Full Idea
The trouble with 'flourishing' as a translation of 'eudaimonia' is that animals and even plants can flourish, but eudaimonia is possible only for rational beings.
Clarification
'Eudaimonia' is something like 'happiness' or 'successful living'
Gist of Idea
Animals and plants can 'flourish', but only rational beings can have eudaimonia
Source
Rosalind Hursthouse (On Virtue Ethics [1999], Intro)
Book Reference
Hursthouse,Rosalind: 'On Virtue Ethics' [OUP 2001], p.9
A Reaction
'Flourishing' still seems better than 'happy', which is centrally used now to refer to a state of mind, not a situation. 'Well being' seems good, and plants are usually permitted that.