The Collaborative International Dictionary of English v.0.48:

madagascar plum \madagascar plum\ n. (Bot.)
   A small shrubby tree (Flacourtia indica) of Madagascar
   cultivated in tropical regions as a hedge plant and for its
   deep red acid fruits resembling small plums.

   Syn: governor's plum, governor plum, Madagascar plum,
        ramontchi, batoko palm, Flacourtia indica.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Madagascar plum
    n 1: small shrubby tree of Madagascar cultivated in tropical
         regions as a hedge plant and for its deep red acid fruits
         resembling small plums [syn: governor's plum, governor
         plum, Madagascar plum, ramontchi, batoko palm,
         Flacourtia indica]