There is quite a bit of confusion about how a “red” maple tree can end up with yellow foliage. The leaves contain chlorophyll, which is green during the spring and summer. Even though the green chlorophyll is dominant, there are separate red cells present that are not yet visible. As the tree goes dormant in fall, the green chlorophyll slowly fades while the red cells begin to dominate. There is just enough green left that combines with the red resulting in yellow or orange foliage.