>While some botanists like to limit the term "plastid" to only refer to
>chloroplasts and similar plastids, in general the term means any
>organelle with a chromosome that presumably is derived from an
>endosymbiotic event, and this definition would include mitochondria
>and similar organelles as well.
I am not a botanist and I have never heard the term plastid used in
reference to mitochondria. The definition of plastid I know is:
A member of a family of organelles unique to plants having their own
small genome and enclosed by a double membrane (chloroplasts, chromoplasts,
leucoplasts, tonoplasts, etc.)
Taken from Alberts et al Mol Biol of the Cell
Graham