KNOXVILLE, Tenn. (WATE) — Leaves are green because of chlorophyll. This is a green pigment within the leaves that help to trap sunlight and create food for the plant during the growing season, which is spring and summer.
As the seasons move from summer to fall, the sun angel lowers and the intensity of the sunlight decreases. As this happens, cells form at the base of the leaf and stop carrying fluids through it.
When the fluids stop, the other color pigments within the leaf are produced making the leaf another color. Chlorophyll is also no longer being produced within the leaf.
The fluids stopping also mean that the leaf is no longer getting any nutrients. This is why the leaf will fall off the tree shortly after it stops being green.
