When days grow short and nights grow long, trees start to grow a corky layer that cuts through every leaf-base stem. Like falling books, unloved, condemned.
No chlorophyll to ink leaf’s page, green’s superficial stories fade revealing deeper colour’s signs, like reading in-between the lines.
Xanthophylls are coded yellow. Anthocyanins, red-purple. Carotinoids have orange gowns while tannins turn their pages brown.
Here’s a lovely link showing all those leafy autumn colours: