Why are blue flowers such a rarity in nature?
BBC says, “Blue is rare in living nature as it is a colour that is associated with organic molecules in alkaline conditions: few living systems have an alkaline chemistry. The morning glory flower, for instance, starts off the day an intense cerulean, fading to an insipid mauve at sundown as the alkalinity in the flower decreases.” Basically, the article is saying that blue is associated with basic pHs. Anthocyanins, a plant pigment, are red in acidic conditions, blue in basic ones, and purple in neutral. This is why you can have either pink or blue hydrangeas. Most organisms exist at a neutral or slightly acidic pH. JBC says, “Considering the spectral diversity of pigment-based coloration in animals one can conclude that blue pigments occur relatively rare. As a rule blue coloration results from light diffraction or scattering rather than the presence of a blue pigment. At least partially this fact is explained by an inevitably more complex structure of blue pigments compared to yello
