The Collaborative International Dictionary of English v.0.48:

Melastoma \Me*las"to*ma\, n. [NL., fr. Gr. me`las black + sto`ma
   mouth.] (Bot.)
   A genus of evergreen tropical shrubs; -- so called from the
   black berries of some species, which stain the mouth.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Melastoma
    n 1: type genus of Melastomataceae; Asiatic shrubs with leathery
         leaves and large purple flowers followed by edible fleshy
         black berries [syn: Melastoma, genus Melastoma]