Plant pigments are essential for photosynthesis, a process that supports all plant and animal life. They also play a key role in sensing light to regulate plant development and in establishing the communication between plants and the animals around them. Further, some plant pigments are the source of nutritional compounds required for or useful to the diets of humans and other animals.

The major classes of visible plant pigments are chlorophylls, carotenoids, flavonoids (including anthocyanins), and betalains. Each of these classes of pigments is composed of several individual compounds. For example, there are two major chlorophylls in higher plants, while there are hundreds of carotenoids and flavonoids that occur in nature. Phytochrome is a blue-green plant pigment that is not plentiful enough to be visible but serves as an important sensor of light, which stimulates plant growth and development.

Pigment Occurrence and Function

All plants contain chlorophylls and...