| Leaves of plants like cabbage are purple in color, then how are they able to carry out photosynthesis? |
| Question Date: 2015-04-14 |
| Answer 1: Yes, we usually think of plants being green. Itsounds like you know that the green pigmentchlorophyll is important in photosynthesis. Whatmight be news is that there are actually manypigments that can trap light forphotosynthesis. If you live in a place where leaves change colorin the fall, you have seen some of the colors ofother pigments. Those leaves were green before.Then the tree stopped putting chlorophyll into theleaves, and the sunlight broke down thechlorophyll that was there. The other pigmentswere left behind. They were there all along, youjust couldn’t see them. The different pigments use different colors oflight. You know the colors of the spectrum if youhave ever seen a rainbow. We can tell which colorsa plant is NOT using because those are the colorsbeing reflected to our eyes. They are absorbingand using the other colors. So your averageplant, like corn, is reflecting the green lightand using the other colors. The purple cabbage isusing the green and other colors, and reflectingthe purple. Light at the purple end of the spectrum has moreenergy than light at the red end. Why do youthink purple is not a very common plant color?You might be interested in studying plant ecologyor plant physiology. Thanks for asking, |
| Answer 2: The leaves of purple plants still have chlorophyllwhich looks green to us. So since they havechlorophyll, they can carry out photosynthesis.However, some plants have a lot of compoundscalled anthrocyanins which can be red or purple incolor. If a plant has enough anthrocyanins,the purple will block out the green color eventhough the chlorophyll is still there. In fact,some apples are red on the side that gets sun andgreen on the side that’s in the shade. This isbecause in the shade they need to up their amountof chlorophyll to get enough sugar fromphotosynthesis so they appear greener. The reasonthat some plants are purple is that the colorattracts bugs and animals that can help dispersethe seeds of the plant. The purple color canalso act as a “sunscreen” so that leaves don’tget to much sun. |
| Answer 3: Cabbage leaves are part of the flower, not thephotosynthesizing part of the plant. Also, justbecause they have anthocyanin pigments that makethem purple, they still also have chloroplastswith chlorophyll as well, just less of it. It'snot the green color that allows plants tophotosynthesize; it's the presence ofchlorophyll, which just happens to be green,which is why most plants are green without anyother pigments. Click Here to return to the search form. |
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