carotenoid

Any of a group of yellow, orange, red, or brown pigments found in many living organisms, particularly in the chloroplasts of plants. There are two main types, the carotenes and the xanthophylls. Both types are long-chain lipids (fats).

Some carotenoids act as accessory pigments in photosynthesis, and in certain algae they are the principal light-absorbing pigments functioning more efficiently than chlorophyll in low-intensity light. Carotenoids can also occur in organs such as petals, roots, and fruits, giving them their characteristic colour, as in the yellow and orange petals of wallflowers Cheiranthus. They are also responsible for the autumn colours of leaves, persisting longer than the green chlorophyll, which masks them during the summer.