to epidermal cell walls or within elongated chloroplasts, but it canalso be the result of a helical arrangement of cellulose fibrils (Fig. 5b).Iridescence in leaves is thought to produce particular intensity ratiosof incident radiation bands that can penetrate to phytochrome centres and thus affect the development of the plant, although the photonic effect may have other functions. Structural colour in fruit skinreduces post-maturation discolouration and ultimately improvesdispersal20. Interestingly too, convexly curved epidermal cells on thesurface of several particular species of plant appear to act asmicrolenses21, resulting in increased photosynthetic flux density onspecially oriented chloroplasts at specific depths within the plants’leaves.