I love the story about the colour blue in nature. I’ve gone on about how there is no known vertebrate with an actual blue pigment; the rest of the colour blue we see is actually structural pigmentation. On the recent field course I taught in Kenya, I had the following conversation with a student.
Me: You know, there is no animal with a blue pigment.
Me: So how come some animals look blue?
Student: SOIMF** YOU’RE BLOWING MY MIND***
Here’s a great video on it:
NB: The video mentions a butterfly with an actual blue pigment! Cool!
A recent blog post on Jeff Ollerton’s Biodiversity Blog got me thinking about the colour blue again. His post was on blue flowers and I thought, wait, I know animals don’t have blue pigments, but do plants? The answer was yes!
Plants DO have a blue pigment…actually, they have water soluble flavonoid pigments that range from red to blue based on the pH****. (How cool is that?!) Gardeners will recognize this phenomenon in Hydrangeas, which will be blue in acid soils and pink or red in basic soil.
As mentioned in Jeff’s blog, however, what we would consider “true blue” (as opposed to shades of purple) is still relatively rare in flowers. A few examples off the top of my head are Meconopsis (blue poppies, Papaveraceae), Myosotis (forget-me-nots, Boraginaceae), Borago (Borage, Boraginaceae), and Nigella (love-in-the-mist, Ranunculaceae), Centaurea (cornflowers, Asteraceae), and Sisyrinchium (blue-eyed-grass, Iridaceae).
But I’m definitely not the first person to think about blue flowers. Plants are bred and genetically modified to produce blue pigments (even dyed in grocery stores), and now they have created a chrysanthemum that expresses a blue pigment (from Delphinium, I think). There’s a real market for true blue! There’s even a RadioLab episode on it (and you know I love RadioLab). Listen here (it’s awesome): http://www.radiolab.org/story/211213-sky-isnt-blue/
Do you have a favourite blue flower? Or do you think some of the ones I picked are not “true blue”? Argue below…
***It’s fun to do this to students.
****Some people argue that these anthocyanins are not actually blue pigments either! As far as I understand it, their argument is that the chemical modification of pigments in order to make them blue means the pigments are not truly blue. You can read David Lee’s excellent book “Nature’s Palette” (for free!) here: http://priede.bf.lu.lv/grozs/AuguFiziologijas/Augu_resursu_biologija/gramatas/Plant%20Color.pdf
“The problem of blue flowers” starts on page 180 if you want to skip straight to that.