Why are plants green?
Plants are green because they have a substance called chlorophyll in them. Understanding why chlorophyll is green requires a little biology, chemistry and physics. If we shine white light on chlorophyll, its molecules will absorb certain colors of light. The light that isnt absorbed is reflected, which is what our eyes see. A red apple appears red because the molecule of pigment in the apples skin absorbs blue light, not red. Thus, we see red. Chlorophyll molecules absorb blue light and some red light. The other colors are reflected resulting in the green color that we associate with plants. Plants get their energy to grow through a process called photosynthesis. Large numbers of chlorophyll molecules acts as the antenna that actually harvest sunlight and start to convert it in to a useful form. Heres where the absorbent properties of the chlorophyll molecule come into play. It turns out that eons of evolutionary design have matched the absorbance of chlorophyll to the actual color of
I sang of leaves, of leaves of gold, and leaves of gold there grew; Of wind I sang, a wind there came and in the branches blew. Beyond the Sun, beyond the Moon, the foam was on the Sea And by the Strand of Ilmarin there grew a golden Tree. -the Lady Galadriel -Lord of the Rings, J. R. R. Tolkien In Lord of the Rings, Tolkien uses the imagery of colors to help paint the picture he wants us to see. The good guys wear white, the bad guys wear black. When he creates the enchanted forest, Lothlórien, he calls it the Golden Wood, and makes the leaves gold. He stirs a fair amount of magic into the forest as well, with Galadriel the wearer of one of the magic rings, but he plays on our expectations as well. The name itself-The Golden Wood-is alluring on its own. There are at least two reasons. First, there is the fascination humans have with gold. Anything golden must be special. Second, the trees are the wrong color. We are so accustomed to having plants be green that any one that differs mus
Before we get into an explanation of fall colours we need to understand why plants are green in the first place. During the growing season plant leaves appear green to us because they reflect green light. Or more correctly, the chlorophyll inside the leaves reflects green light. Most of the materials that make up a leaf are colourless or clear. Leaves and the cells they are constructed of are mostly water, just like us. Chlorophyll is that miraculous molecule that captures sunlight and allows plants to make their own food, a process called photosynthesis. The energy of sunlight is used to recombine water and carbon dioxide molecules into simple sugars and oxygen: that rather important plant waste product! Chlorophyll molecules absorb, and make use of sunlight from the red and blue ends of the spectrum. They’re not good at absorbing green, so this is transmitted or reflected, and bounces to our eyes. Plants are green because they waste green light. Actually, they waste a fair bit of the
Well you are spot on about it being chlorophyll inside the chloroplasts that gives a plant the green colour. There are other pigments in the leaves too, such as xanthophylls (yellows) and carotenoids (yellows, oranges and reds). These pigments are also used in photosynthesis but occur in lesser quantities than the green chlorophyll. The combinations of the different pigments make different shades of green. Now the reason that plants look green is that they are trying to obtain energy from the sun using a particular part of the light spectrum, mainly the red and infra red wavelengths. If you remember from your physics classes the colour you see is the colour that is reflected from the object, the other colours are absorbed. So in the case of green plants, the green wavelength is reflected and all the other colours, especially reds and blues, are absorbed to drive the energy cycle in the plants. Chlorophyll does best in the red (around 670 nm) and blue (around 500 nm) areas of the spectr
In Kiang’s case, she hopes the answer to this question may help astronomers spot life on other planets from the relative comfort of their mountaintop or orbital observatories. So, why are plants green and not blue, orange or mauve? Are all plants green? Have they always been green? Might they be different colors on different planets? Colors are energy, made manifest as light. Our perception of green foliage results from the mix of light photons that plants fail to capture with their chlorophyll pigments. Plants preferentially absorb high-energy blue photons and lower-energy, but high-volume red photons to build sugars from carbon dioxide and water during photosynthesis. Our cherished lawns and gardens reflect unabsorbed light in the green part of the spectrum back to our admiring eyes. Because the sun produces all this dazzling light energy that runs the world, Kiang and others have scrutinized her stellar attributes. How does our sun compare with other stars that might be nurturing li
