Accessory pigments are pigments in plant leaves other than chlorophyll a that assist in the process of photosynthesis. Accessory pigments function by extending the range of light wavelengths that a plant absorbs. Accessory pigments give plants unique colors.
Chlorophyll a is the primary light-absorbing pigment in plant leaves. It absorbs light wavelengths in the red and blue range, and reflects back green waves, which gives most leaves their distinctive green color. Different accessory pigments absorb different wavelengths of light. Carotenoids, the most common accessory pigments, absorb extra blue wavelengths. In addition to aiding in the creation of energy from photosynthesis, the carotenoids also protect chlorophyll a from damage from too much light radiation. Chlorophyll b, c and d, lycopene and phycobiliproteins are additional accessory pigments found in some plants.
Algae and cyanobacteria, a single-celled organism that lives in the water and uses photosynthesis, contain many accessory pigments to maximize energy production in their water habitats. Phycobiliproteins allow these water organisms to absorb most wavelengths of light, including much of the green range. Many species of algae and other water plants have red or yellow coloring due to their unique accessory pigments that absorb the wavelengths of light that travel best through the water. The specific accessory pigments found in a water plants help scientists determine the characteristics of the plant's natural ecosystem.