What is a Chloroplast and what is its Function Plastids : Plastids are organelles enclosed by a double membrane found in all plants.Historical Account : E.Heckel (1865) gave the term plastid. Plastids are largest cell organelles.Ultrastructure :Plastids occur in most plant cells and are absent in animal cells. Plastids are self replicating organelles like … [Read more...] about What is a Chloroplast and what is its Function