Iridescence is a form of structural colour which changes hue according to the angle from which it is viewed. Blue iridescence caused by multilayers has been described on the leaves of taxonomically diverse species such as the lycophyte Selaginella uncinata and the angiosperm Begonia pavonina. While much is known about the role of leaf pigment colour, the adaptive role of leaf iridescence is unknown. Hypotheses have been put forward including 1) iridescence acts as disruptive camouflage against herbivores 2) it enhances light sensing and capture in low light conditions 3) it is a photoprotective mechanism to protect shade-adapted plants against high light levels. These hypotheses are not mutually exclusive: each function may be of varying importance in different environments. To understand any one function, we need a interdisciplinary approach considering all three potential functions and their interactions. The objective of my research would be to test these hypotheses, using animal behavioural and plant physiological methods, to determine the functions of leaf iridescence and how the plant has adapted to the reflection of developmentally vital wavelengths. Use of molecular and bioinformatics methods will elucidate the genes that control the production of this potentially multifunctional optical phenomenon. This research will provide a pioneering study into the generation, developmental impact and adaptive significance of iridescence in leaves. It would also answer questions at the frontiers of several fields including those of plant evolution, insect vision, methods of camouflage, the generation and role of animal iridescence, and could also potentially inspire synthetic biomimetic applications.