There are small bodies in plant cells that are made of colored material. They are named plastids. The CHLOROPHYLL in plastids makes the leaves green. A carrot has orange plastids, and a beet has red ones. The plastids in a white potato have no color. The plastids help a plant to make food or to store it for use later.
Plastids are formed from the cytoplasm in the cell or from the division of other plastids. Usually plastids have a definite shape and are the center of a special chemical action. Chloroplastids (chloros—green) make carbohydrates from carbon dioxide, water, and light—the process of PHOTOSYNTHESIS.
Chlorophyll is always contained in plastids, except in blue-green algae and photosynthetic bacteria. Chromoplastids (chromos—color) may contain two chemicals—XANTHOPHYLL and carotenes—which give the yellow color to many fruits, vegetables, and autumn leaves. Leucoplastids are colorless and contain starch.
