街路樹を見て思うこと

Other day, I went for a walk near my house.
When I went to a certain place, I stopped there and saw the trees along the street.There were some trees turned red in the autumn, and others trees stayed green.
All the same speceis.
What's the differences?
I perceived that the trees having red leaves had been received the amount of lights, on the other hand the green leaves trees had not had.
Maybe there are some relations between the autumn leaves and phototoropism...?

I went back home and searched some information or knowledge.
...not found.
No kidding.
indeed, I was not good at resarching.
But...but...
There are little information!
...Why?

I think that this is an interseting topic.
phototoropin? phytochrome? plastid?peptide hormone?...or the other reasons?
While I was imagining such things, the sun was setting...