The color of plants is perhaps the most mentioned characteristic of plant life on this planet. Although the bulk of the plant cell is colorless, the green appearance of plants exists because of a pigment found in the chloroplast.
Chloroplasts and Chlorophyll
The chloroplast, the organelle within plant cells that is responsible for much of the process of photosynthesis, contains the pigment chlorophyll. Chlorophyll is a chelate, a substance where a central metal ion (in chlorophyll, it's magnesium) is bonded to a large organic molecule. Chlorophyll's absorption spectrum shows that it strongly absorbs red and blue-violet light. Because of this, the light it reflects and transmits appears green.
Role in Photosynthesis
Chlorophyll's most important role is within the process of photosynthesis where it assists in the transfer of electrons from water to carbon dioxide.
The intense green color of chlorophyll suggests that it would be useful as a commercial pigment or dye. In fact, Natural Green 3 is a green dye made from a type of chlorophyll and is used in soaps and cosmetics.
The first half of the name is from the Greek "chloros," which means "yellowish green."