Shine on... secret of buttercups revealed
IT HAS taken them a century to shed any light on it… but scientists have finally discovered why a buttercup flower shines so brightly.
For decades children in meadows have been playing a game of placing the flower under their chins.
If their neck lights up yellow, conclusive proof they like butter.
Now researchers know why the petals give off such a radiant glow.
They found that buttercup’s outer layer, or epidermis, contains a yellow pigment but is just one cell thick.
Dr Casper van der Kooi , of Lausanne University, in Switzerland, said: “Below is an air chamber, meaning light is reflected on both sides of the epidermis where the cells and air meet.
“The colour generating mechanism is similar to oil on water or a soap bubble.
“As the cell layer is very smooth and thin, optical interference occurs and the reflected colours merge, which makes the petals seem glossy.”
The buttercup’s thin pigmented film is unique in the plant world. But Dr van der Kooi said it’s butterflies use similar structures to produce colour – as do some birds. The findings of his team are published in the Journal of the Royal Society Interface and include speculation about the reason for the buttercup’s brightness. He said: “Under the right conditions, the gloss reflecting from the epidermis can produce a bright flash visible to pollinating insects from a great distance.” The buttercup is also “heliotropic”, meaning its flowers tilt to the sun – especially on cold days. The petals form a paraboloidshaped cup like a satellite dish, reflecting sunlight towards the central area of the flower, where the reproductive structures are located. Dr van der Kooi said: “We are still measuring but our hypothesis is that this light helps to increase the temperature of the reproductive organs, which enhances seed and pollen maturation.” But a word of caution: They are poisonous for humans and cattle.