The colour of leaves

How do leaves get their green colour?

It is all to do with the leaf structure and light. Leaves absorb sunlight and take in carbon dioxide from the atmosphere as an energy source to turn water and CO2 into glucose (sugar) to make food for the plant. Chlorophyll is the molecule/pigment which allows this process to happen as it is the absorber of the light.

It is found within the chloroplasts of the leaves and plants. Carotenoids, are also found in leaves such as lutein which is yellow in colour, each carotenoid absorbs different light and the amount of chlorophyll effect the intensity of the green colour and this is why there are varying shades of green seen in leaves.

Certain wavelengths of light within the visible light spectrum are absorbed by Chlorophyll. The pigment absorbs mostly the blue and small proportions of red light from the electromagnetic spectrum, hence its intense green colour. The video below explores this idea in more detail.

Why are evergreen leaves always green?

Deciduous trees lose their leaves each autumn and lay dormant until spring where there are longer hours of sunlight in order for them to photosynthesis.  Deciduous trees close up the little holes where the leaves attach so they don’t lose moisture or water to enable them to survive the winter. Evergreen plants and trees do not go through this major change or process but instead they keep their vibrant green leaves all year round. But why? Their leaves are more resistant to the cold and to the loss of moisture due to their waxy coating which protects them. The plant requires little amounts of sunlight because of this therefore shorter day do not affect the plant and its ability to photosynthesise.

References:

Causes of Colour. (n.d.). What is the role of chlorophyll?. [online] Available at: http://www.webexhibits.org/causesofcolor/7A.html [Accessed 23 Apr. 2017].

Pappas, S. (2010). How Do We See Color?. [online] Live Science. Available at: http://www.livescience.com/32559-why-do-we-see-in-color.html [Accessed 23 Apr. 2017].

R.A.W Arboricultural Consultancy. (2010). Why are leaves green?. [online] Available at: https://www.rawtreecare.co.uk/why-are-leaves-green/ [Accessed 23 Apr. 2017].

Rees, E. (n.d.). How do evergreen trees keep their greenness throughout the winter?. [online] How it Works Daily. Available at: https://www.howitworksdaily.com/question-of-the-day-how-do-evergreen-trees-keep-their-greenness-throughout-the-winter/ [Accessed 23 Apr. 2017].

Rosenfeld, J. (2016). Why Do Some Trees Keep Their Leaves in Winter?. [online] Mental Floss. Available at: http://mentalfloss.com/article/72975/why-do-some-trees-keep-their-leaves-winter [Accessed 23 Apr. 2017].

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