plastid

General name for a cell organelle of plants that is enclosed by a double membrane and contains a series of internal membranes and vesicles. Plastids contain DNA and are produced by division of existing plastids. They can be classified into two main groups: the chromoplasts, which contain pigments such as carotenes and chlorophyll, and the leucoplasts, which are colourless; however, the distinction between the two is not always clear-cut.

Chloroplasts are the major type of chromoplast. They contain chlorophyll, are responsible for the green coloration of most plants, and perform photosynthesis. Other chromoplasts give flower petals and fruits their distinctive colour. Leucoplasts are food-storage bodies and include amyloplasts, found in the roots of many plants, which store large amounts of starch.