I notice that certain (wild) flowers have the same colour, although they are not closely related. For example, the yellows of the dandelion (Taraxacum) and the buttercup (Ranunculus) are, at least to my eyes, identical (my observations are in the Netherlands).
I know that the colour is intended to attract insects; is this parallel evolution or are there certain biochemicals which provide colour and are easy for the plant to synthesize? Or something else?
Edit: I used the buttercup and dandelion because that was the first pair I found physically close enough for a photo; the cowslip, celandine and charlock mustard are all (to my eyes) the same yellow. I have also seen similar blues, reds and violets, and shall try to collect examples next time I go cycling on the dyke.
When I look at colour tables like https://en.wikipedia.org/wiki/Web_colors#Extended_colors I see numerous colours which I do not recall ever seeing in wild flowers.
Comments seem to suggest a biochemical cause; can anyone confirm (or disprove) it?