Fall is coming up soon, and it brings many exciting things like Halloween, pumpkins, and so much more! One of the most common things people think of when talking about fall is leaves and more specifically, how they change color. The big question with this beautiful tradition is “why?” The answer to this is more complicated than it might seem.
When a tree senses that days are getting shorter, and less light is getting to its leaves, it stops producing chlorophyll, which is the chemical that takes in light from the sun, and starts breaking it down. Chlorophyll is naturally green and is what gives leaves their usual color, but when it’s not there, other colors show through. Carotenoid is a pigment that is yellow or orange, which appears when there is less chlorophyll in the leaf. Anthocyanin, which is harder for a tree to produce, can also be seen in the fall as a red or purple color. Both of these pigments were always there, but now that there is no chlorophyll, they can actually be seen.
When chlorophyll breaks down, all the nutrients it collected are absorbed by the tree, leaving only these pigments. As a result, the tree essentially cuts the leaf off from the rest of the tree, leaving it barely attached. And eventually, it falls.
Now that you know the science behind this phenomenon, the next time you see a falling leaf, you can appreciate how incredible it really is.