The "Peacock Begonia," Begonia pavonina, is named not for its flowers, but for its striking, iridescent blue leaves. This is one of the rare plants that displays blue structural color. There is no blue pigment in the leaf cells, but they reflect blue light, making the leaf shimmer with turquoise hues. Examples of structural color in the animal world would be the iridescent blue wings of a Morpho butterfly or the shiny green head of a mallard duck. For a nice review article on this topic, see: Glover, B. J., & Whitney, H. M. (2010). Structural colour and iridescence in plants: the poorly studied relations of pigment colour. Annals of Botany, 105(4), 505-511.
Begonia pavonina is native to Malaysia, and inhabits the densely shaded forest floor. Recent research suggests that the weird, blue leaves are an adaptation to help the plant make maximum use of what little sunlight is available to it. For a review of this type of adaptation in shade-growing plants, see: Thomas, K. R., Kolle, M., Whitney, H. M., Glover, B. J., & Steiner, U. (2010). Function of blue iridescence in tropical understorey plants. Journal of the Royal Society Interface, rsif20100201.
