Leucoplasts are organelles, cell structures surrounded by membranes, in plant cells that store starch, lipids or proteins, or have biosynthetic functions creating a variety of organic compounds. They are a type of plant organelle known as a plastid, a category that includes chloroplasts.
Leucoplasts used for storage fall into three categories. Leucoplasts that store starch are called amyloplasts. Leucoplasts that store lipids are called elaioplasts. Those that store proteins are called proteinoplasts. Elaioplasts and proteinoplasts are often found in seeds. However, in many plant cell types, leucoplasts are not used much for storage. In these cells, they create organic compounds rather than storing them. Some synthesize fatty acids, others amino acids and some generate more specialized compounds. Immature chloroplasts, as well as chloroplasts that have been deprived of light, do not have pigmentation and can also be considered leucoplasts. Once exposed to light, however, they produce the compounds necessary for photosynthesis and cease being leucoplasts.
Unlike other plastids, leucoplasts have no colored pigments. Leucoplasts are generally much smaller than chloroplasts and have a variable shape. In root cells and others, different leucoplasts are often connected in complex networks by structures known as stromules. Leucoplasts are often clustered around the nucleus of the cell during certain stages of development.