Which pigment class gives autumn leaves their yellow and orange colors?

Carotenoids are the pigment class that gives many autumn leaves their yellow and orange colors. These pigments, including yellow xanthophylls and orange beta-carotene, are often present in leaves throughout the growing season but hidden by abundant green chlorophyll.

As deciduous leaves prepare to fall, chlorophyll is broken down and its green masking effect fades. Carotenoid colors then become visible, producing the golden and orange foliage associated with species such as birch, aspen, ash, hickory, and some maples. Carotenoids also help plants absorb light and protect photosynthetic machinery from excess energy.

Anthocyanins are the common alternative people confuse with carotenoids. They are responsible for many red and purple autumn hues and are often synthesized during senescence rather than simply unmasked. Autumn color is therefore not produced by one pigment alone: yellow and orange usually reflect carotenoids, while red and purple commonly involve anthocyanins. Weather, light, temperature, and species-specific chemistry influence the final display.