If it has four leaves, it's said to be lucky (6)
I believe the answer is:
clover
(Other definitions for clover that I've seen before include "Three-leaved wild plant" , "A four-leafed one is lucky" , "Plant used as fodder (which it's good to be in)" , "in which we can live luxuriously" , "Another trefoil, sometimes with lucky four leaves" .)