plastide

 A formative particle of albuminous matter; a monad; a cytode. See the Note under Morphon.  Haeckel.  [1913 Webster]

 any of several types of minute granules found in the protoplasm of vegetable cells, having their own membrane, robosomes, and DNA. Among plant cells the most common are chloroplasts, which contain the chlorophyll and the photosynthetic machinery of the cell. They are divided by their colors into three classes, chloroplastids, chromoplastids, and leucoplastids.  [1913 Webster]