Which type of chlorophyll is most abundant in plants?

Chlorophyll a is the most abundant type of chlorophyll in plants. It is the primary photosynthetic pigment in oxygen-producing photosynthesis, absorbing light energy that ultimately drives the formation of ATP and NADPH.

Chlorophyll a absorbs light most strongly in parts of the blue-violet and red regions of the visible spectrum. It reflects more green light than it absorbs, which helps give many leaves their characteristic green appearance. Inside chloroplasts, chlorophyll a is embedded in protein-pigment complexes within the thylakoid membranes.

Chlorophyll b is also important in plants, but it is considered an accessory pigment. It absorbs somewhat different wavelengths and transfers the captured energy to chlorophyll a, broadening the range of light that a leaf can use. This partnership improves light harvesting, especially when available light is limited.

The letter distinction does not mean chlorophyll a is found only in plants. It occurs broadly among oxygenic photosynthetic organisms, including green algae and cyanobacteria. Chlorophyll c and chlorophyll d are associated mainly with particular algal or bacterial groups, while chlorophyll e is much rarer. The pigments should also not be confused with carotenoids, which assist with light harvesting and protect photosynthetic machinery from excess light.