Creeping Buttercup - A Short Study - Part 2

Ever since watching the television programme Wild Things and hearing about the genetic mutation that occurs every seven years and results in a plant with additional petals, I've been on the look out for such a plant. Which along with research about the buttercup lights up your chin, will be discussed in part 2 of this study. Part one is available here.

Imagine my surprise when one popped up in my back garden! Normally creeping buttercup has 5 petals, but there are plants that flower with additional petals. The additional petals can also be used to date meadows in which they occur.

As creeping buttercup primarily reproduces by sending out creeping runners, a meadow of hundreds of buttercup flowers can be made or just a few plants. This means that each new plant created by this vegetative reproduction carries identical genes to the parent plant. Over time some of these genes begin to mutate (somatic mutation), resulting in flowers with an extra petal.

A 2011 study found that each plant that flowers with additional petals in a sample of 100 plants was found to equate to approximately 7 years. Therefore a meadow with a known age of around 100 years could be expected to contain about 14 flowers with these extra petals. This method works well in estimating meadows up to 200 years old.

But this isn't the end of the wonders of the buttercup, as research published in 2011 goes to show. A research team look in to the 'directional scatter' from the buttercup flower. This directional scatter is often used by children holding a buttercup under a friend's chin to see if they like butter.

Directional scatter, as displayed by my beautiful assistant.

The earliest documented research regarding this was done by Mobius in 1885, who showed that the oily appearance of the yellow flower is caused by a pigment. This current research found that the structure of the petal, particularly the epidermal layer has a large part to play. The epidermal layer is the outermost layer, and is akin to our skin. In the buttercup petal the epidermis has two extremely flat, semi-transparent surfaces that bear pigments that reflect yellow light with a high intensity. The epidermis is separated from a paper-white starch layer in the petal by a layer of air. This interplay between the layers serves to double the gloss of the petal allow for a highly directional reflection.


So the next time you're in a field playing the game to find out who likes butter, remember is has nothing to do with whether you like butter. Instead it is all to do with the biology of the buttercup and the lengths it will go to attract potential pollinators! Oh, and while you're there you may as well check for some 6 petalled buttercup flowers - perhaps they might become the new 4 leaf clover.

References
Warren J. (2009). Extra petals in the buttercup (Ranunculus repens) provide a quick method to estimate the age of meadows., Annals of botany, PMID: 19491088  
Vignolini S., Thomas M.M., Kolle M., Wenzel T., Rowland A., Rudall P.J., Baumberg J.J., Glover B.J. & Steiner U. (2011). Directional scattering from the glossy flower of Ranunculus: how the buttercup lights up your chin., Journal of the Royal Society, Interface / the Royal Society, PMID: 22171065
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