Why does a plant use several pigments instead of one or two?Why are plant leaves green?

Question

Why does a plant use several pigments instead of one or two?Why are plant leaves green?

Answer 1

Pigments are a way for a plant to absorb the sun's energy in the form of light (photosynthesis). The different colored pigments absorb different wavelengths of light and pass it on directly to the plant to make energy, except for one class called the carotenoids, which much pass it on the the chlorophyll before anything happens

The plants leaves are green because they absorb all the other wavelengthss (red, blue, oragne etc) except the green one, and the reflection of the green is what our eyes see.

Answer 2

The several other pigments that are found with chlorophyll a multi-task. They work with chlorophyll a to provide energy by absorbing light from the sun and other jobs as well. Some accessory pigments help protect the plant while collecting energy, others help regulate the photosynthetic process.

Chlorophyll a is limited in its range of light capture so it pairs up with pigments that capture light in the wavelengths it misses especially the blue spectra next to the UV. So one additional job for these accessory pigments is to protect the plant from UV damage. Plants sunburn, too.   Xanthophylls are a common type of carotenoid that protecs by absorbing excess light energy and dissipating it in the Xanthophyll Cycle.

A third type of job is regulation. Chlorophyll b's main function is to collect energy but a secondary function is to regulate the light harvesting antenna size.

http://www.lowtem.hokudai.ac.jp/plantada...

The third photosynthetic pigment class, Phycobilins only photosynthesize in Cyanobacteria (bluegreen algae) and Rhodophyta's (red algae) but always as a partner to chlorophyll a. These work under water where light penetrates less.

Last, there are hundreds of pigments in plants doing jobs that are not photosynthetic. Recent literature reports some 550 anthocyanins.  Some are known to provide red, purple or magenta colors to flowers, leaves and fruit. Plus there are over 600 known carotenoids providing yellow, orange or red colorations.  Some breakdown products of carotenoids are fragrant, making the main scent in some roses, black tea, tobacco, grapes and many fruits. Both of these groups of pigments provide regulation, protection from free radicals and UV, as well as color and fragrance to the many parts of plants.

http://www.chm.bris.ac.uk/motm/carotenoi...