Y ddeilen hon: natur, tarddiadau a phwrpas lliwiau dail (This leaf: the nature, origins and purposes of leaf colours)

The state of the environment and the passage of time are reflected in the changing colours of the plants around us. Chlorophyll, the green pigment of leaves, captures the energy of sunlight that drives photosynthesis and powers the biosphere. The disappearance of chlorophyll from autumn leaves reveals the yellows and oranges of another family of plant pigments, the carotenoids. Carotenoids protect plants from stresses and are also responsible for the colours of many flowers and fruits. In autumn, the leaves of species such as maples make red and purple anthocyanins, which are members of a diverse family of pigments and defence chemicals. Plants use pigments to send signals to pollinators, dispersers and predators, among which are humans, who have a special physiological and psychological responsiveness to the plant chemistry that colours our world.