What causes some trees to have purple leaves?
One way a plant uses pigments is in chromoplasts (similar to chloroplasts, where chlorophyll is found, but not photosynthetic). Chromoplasts protect the tree from oxidation. These will be found in plants with red or copper leaf colors. A Copper Beech tree has anthocyanin, a pigment that reflects red and acts as an antioxidant. Thus the leaves of the copper beech have more red chromoplasts that overwhelms the chloroplast’s green. The leaves appear deep red in sunlight however when you look at a copper beech in the shade that copper coloration thins out, and you can see the green photosynthetic chlorophyll showing through because the tree is still actively photosynthesizing. Plants with more chromoplasts can survive habitats with marginal resources where they are better protected from both oxidative and UV stress. Chromoplast content varies naturally in plant leaves. Plants with more chromoplasts can survive regions of marginal resources where they are better protected from both oxidativ