Olives are the fruit of the tree Olea europaea, also sometimes called oliveleaf, and mu xi lian in Chinese. Green and black olives are different stages of ripeness, though some varieties are always picked green.
There are 6 subspecies: Olea europaea subsp. cerasiformis aka O. europaea var. cerasiformis or O. europaea var. maderensis; Olea europaea subsp. cuspidata (African, brown or wild olive) aka O. africana, O. chrysophylla, O. cuspidata, O. europaea subsp. africana, O. ferruginea, O.