Color Change in Yellow Popular Leaf.........The first of the yellow popular leaves are beginning to color and fall. Southeastern Indiana has had a wet spring and summer. Why do specific leaves fall before others? Have read a lot about coloration of leaves, still don't fully understand. All I know, people travel many miles to watch them and it seems to make them happier. Macrograph shows the color interfaces within the leaf. Empirical observation indicates the round darker brown area may be the result of an injury. Things have no color, only reflect specific wavelengths of light, that we see as color. I love the fall.