Chlorophyll

Chlorophyll at various scales

Chlorophyll is responsible for the green color of many plants and algae.

A microscope image of plant cells, with chloroplasts visible as small green balls

In plant and algal cells, chlorophyll is concentrated in structures called chloroplasts, as shown in this micrograph of cells in a moss leaf.

A leaf absorbing blue and red light, but reflecting green light

Plants are perceived as green because chlorophyll absorbs mainly the blue and red wavelengths but green light, reflected by plant structures like cell walls, is less absorbed.

There are several types of chlorophyll, but all share the chlorin magnesium ligand which forms the right side of this diagram.

Chlorophyll is any of several related photochemical catalysts and green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words χλωρός (khloros, "pale green") and φύλλον (phyllon, "leaf"). Chlorophyll allows plants to absorb energy from light. Those pigments are involved in oxygenic photosynthesis, as opposed to bacteriochlorophylls, which are related molecules found only in bacteria and involved in anoxygenic photosynthesis.

Chlorophylls absorb light most strongly in the blue and red portions of the electromagnetic spectrum. Conversely, it is a poor absorber of green and near-green portions of the spectrum. Hence chlorophyll-containing tissues appear green because green light, diffusively reflected by structures like cell walls, is less absorbed. Two types of chlorophyll exist in the photosystems of green plants: chlorophyll a and b.