The two major classes of photosynthetic pigment in plants and algae are carotenoids and:

1. Different kinds of pigments exist, and each absorbs only certain wavelengths of visible light. 2. Plants and algae rely mainly on two families of them. 3. Chlorophylls and carotenoids are the two major classes of photosynthetic pigments found in plants and algae. 4. Each class has multiple types of pigment molecules. _Source: OpenStax Biology for AP(R) Courses (CC BY 4.0), Ch 8 'Photosynthesis', sections 8.1-8.3_