It is at this time that friends, relations and students turn to him, an associate professor of horticulture at Purdue University, to again explain why the leaves change color and die. There's something about the trees changing colors in the fall that just captivates people. Even my wife asks me to explain it to her every year. Chorophyll dominates during spring and summer.
Chlorophyll serves as a photoreceptor, or light receiver, for the tree.
Chlorophyll helps plants produce energy through photosynthesis, the process plants use to convert sunlight into sugars and starches. As temperatures begin to drop in the late summer, trees prepare for winter by stopping the production of chlorophyll. The chlorophyll already present in the leaves begins breaking down into simpler compounds, which are stored for the winter in the tree's twigs. The yellow-orange colors in leaves in the autumn are caused by pigments known as carotenoids, and, as their name implies, they also give the characteristic color to carrots. These also play a role in photosynthesis.