I've recently read the following text on a Brazilian physics magazine:
In fall, tree leaves change color from green to yellow, orange and red. Green color comes from chlorophyll. In older leaves, chlorophyll production reduces and green tone goes away, allowing this way that other pigments such as carotene, of yellow-orange color, and anthocyanin, of red color, dominate leaves' colors. Such observed colors come in function of sun radiation's interaction.
As we can see in picture below, chlorophyll absorb solar radiation on blue and red regions; this way, light reflected by the leaves are missing those two tones and we can see them green. Anthocyanin, though, absorb light from blue to green. In this case, light reflected by leaves with anthocyanin show up with complementary colors, i.e., red-orange.
For instance, caroten absorb most of blue-violet spectre.
After this excerpt, the text says that it's easy to check the blue-violet spectre absorption regarding carotene.
It says that since we see caroten as yellow-orange color, we only have to look at the complementary colors of yellow and orange, which are the opposite colors looking at the diagram:
Since the opposite colors for yellow and orange are violet and blue, that's the top absorption: blue-violet spectrum.
My doubt is if that's a valid method indeed. That's because if I use this same method for chlorophylle, it doesn't work quite right, I think. The text says that chlorophylle absorbs solar radiation on blue and red regions. Then, from that perspective and using the method the question's taught us, the complementary colors would be orange and green, and so we would see colors orange-green.
Shouldn't that orange tone be away for a green leaf? Or is that method wrong? For the method, I mean, saying that top absorption colors are complementary for the top reflected color, and they're opposite on that complementary colors diagram.