: The largest cell organelle in the cell is nucleus followed by plastids in the plant cells and mitochondria in animal cells. Plastids (double membraned organelle) are the characteristic of plant cells. They are of several types, such as chromoplast (coloured) i.e. chloroplast (green), phaeoplast (brown), rhodoplast (red) and leucoplast (colourless). The term plastid was given by A. W. F. Schimper.