Plants are green due to the presence of which pigment?

A pigment is a substance that absorbs certain wavelengths of visible light and reflects the rest; the wavelength(s) reflected back to the eye determine the colour the pigment appears. Plant tissues contain several distinct pigment classes, each associated with a different part of the visible spectrum.

Chlorophyll is the primary pigment inside plant chloroplasts responsible for capturing light energy for photosynthesis. It strongly absorbs light in the red and blue-violet regions of the spectrum while reflecting green light. Because chlorophyll is the most abundant pigment in healthy leaves and stems, the green light it reflects dominates what the eye perceives, which is why plants look green.

The other pigments found in plants are real, but each reflects a different part of the spectrum, not green:

• Carotenoids absorb blue-violet light and reflect yellow-orange wavelengths — the pigment behind the colour of carrots and of autumn leaves once chlorophyll has broken down.

• Lycopene reflects red wavelengths — it gives ripe tomatoes and watermelon their red colour.

• Anthocyanins reflect red, purple or blue wavelengths depending on cell pH — seen in berries, red cabbage, and some autumn foliage.

Since only chlorophyll's reflected wavelength corresponds to green, chlorophyll is the pigment responsible for the green colour of plants.