Plastids are double membranous structures. Plastids are of three types: Chloroplast, leucoplast, chromoplast.
Chloroplasts contain its own DNA protein-synthesising machinery.
Leucoplast are of three types: amyloplast, proteinoplast and elaioplast. Amyloplasts can synthesize and store starch. Proteinoplasts store proteins but can not synthesise. Elaioplasts store lipids.
Leucoplasts are colourless plastids which generally occur near the nucleus in non-green cells and possess internal lamellae.