Maryland Tree Expert Practice Test

Fall leaf color comes from pigments that become visible when chlorophyll breaks down with shorter days. Carotenoids are the pigments that give yellow and orange hues; they’re present in the leaf but masked by green chlorophyll most of the time. As chlorophyll fades, carotenoids stand out and produce those yellow-to-orange tones. Reds in fall come from a different pigment class, anthocyanins, which some leaves make in response to sugars and light—but not every tree forms red pigments. Lignin isn’t a pigment that produces bright fall colors; it contributes to browning as tissues degrade. So the color most directly responsible for the yellows and oranges seen in fall is carotenoids, with red tones arising from anthocyanins in some species.