GRAND RAPIDS, Mich. (WOOD) — What makes some leaves change red in the autumn while others finish a golden yellow or orange? It is all to do with the chemical composition hiding inside each leaf.
Let’s start at the beginning: Leaves are generally green due to the abundant amount of chlorophyll swimming inside each one. The green color in each leaf is so bold that it masks the other colors inside.
When our days start shrinking, the trees react to the signal of the coming winter by shutting down chlorophyll production. As the green fades, other colors start to emerge.
The chemicals xanthophyll and flavonoids are always present in yellow leaves, there is just less of them than the overpowering chlorophyll. One of the major parts of the chemical xanthophyll is what is responsible for the yellow color of egg yolks.
Carotenoids are to credit for the orange in any leaf. This is easy to remember because the word “carotenoids” looks a bit like the word “carrot” and it is actually responsible for the painting carrots orange. Carotenoids are present in most brightly colored fruits and vegetables we have.
Just like chlorophyll, carotenoids fade as fall carries on. However, it doesn’t fade as quickly. This allows the vibrant oranges to be seen before the leaves tumble to the ground.
Unlike xanthophyll, flavonoids and carotenoids, the chemical that produces a violent red isn’t always in a leaf. The production of that chemical, called anthocyanin, doesn’t begin until fall starts. The drop in daylight starts the process. Scientists still don’t even know the reason trees make this chemical. The anthocyanin mixes with carotenoids in the leaves to give it the bright red flare.
Ultimately, the fall color show is dependent on the weather. Changeable conditions make for lousy color shows. Wind storms can strip leaves early and a hard freeze will send our colors straight to brown.