Despite appearances – and often therefore assumptions – to the contrary, the intense blue-colour of the fruit of Pollia condensata is not due to pigment(s). Instead, it is another example of so-called ‘structural colour’ (a phenomenon that is much better known – if still incompletely understood – in animals than in plants), as reported by Silvia Vignolini et al. The phenomenon in Pollia fruit (apparently, known as the ‘bling berry’ in recognition of the slang term referring to flashy, ostentatious or elaborate jewellery and ornamented accessories carried or worn by certain individuals) is an ‘example of multilayer-based strong iridescent coloration’, which gives the fruit a ‘striking pixelated or pointillist appearance’. Furthermore, ‘The bright blue coloration of this fruit is more intense than that of any previously described biological material’ (!!). Although the authors mention Pointillism (a painting technique in which small, distinct dots of pure colour are applied in patterns to form an image), it sounds more like surrealism to me. Such an intense blue but which isn’t chemical must be a little bit disappointing to those Agricultural Research Service scientists who are keen to exploit plant anthocyanins – which give blue colours to many plant parts – as pesticides. Structural colour, eh? Bling it on!
About the author
Nigel is a botanist and full-time academic at Bath Spa University (Bath, near Bristol, UK). As News Editor for the Annals of Botany he contributes the monthly Plant Cuttings column to that august international botanical organ. His main goal is to inform (hopefully, in an educational, and entertaining way...) about plants and plant-people interactions.