Conical epidermal cells cause velvety colouration and enhanced patterning in Mandevilla flowers
The majority of angiosperms have flowers with conical epidermal cells, which are assumed to have various functions, such as enhancing the visual signal to pollinators, but detailed optical studies on how conical epidermal cells determine the flower’s visual appearance are scarce. Here we report that conical epidermal cells of Mandevilla sanderi flowers effectively reduce surface gloss, create a velvety appearance and make more efficient use of floral pigments. The interior backscattering yields a cosine angular dependence of reflected light, meaning the flowers approximate near-perfect (Lambertian) diffusers. Together with the large flowers and the tilted corolla tips this generates a distinct visual pattern, which possibly enhances the visibility to pollinators.
- This article is part of the themed collection: Biological and bio-inspired optics