It's a sunny day in summer. This is the time when plants grow, the process they use is the photosynthesis so it can transform the energy of the sun to food.
The season is changing the days begin to shorten after the summer and the trees reconsider its leaves.
A corky layer of cells forms at the leaves' slender petioles, then scars over. Its start coloring for adaptation to their environment.
The leaves stop producing the pigment chlorophyll, and photosynthesis ceases. Thats why their leaves start turning their color to yellow, red and brown.
Before winter it survives by dropping its leaves, and by the end of autumn only a few fragile threads of fluid-carrying xylem hold leaves to their stems.
When the leaves finally fall they crunch and crackle underfoot, they make piles of leaves on the floor and children love playing with those, the leaves stay there until spring were you can make a rich humus.