Hello Gardeners, I’m Amanda McNulty with Clemson Extension and Making It Grow. Hickories, tulip poplars, catalpas, gingkoes and other deciduous trees owe their yellow and golden fall colors to the presence of chemical compounds called carotenoids and flavonoids that served as accessories to the life-giving cycle of photosynthesis that takes place in green leaves. Now that the shorter-lived chlorophyll molecules, responsible for the green color in leaves, are declining in concentration, these