Coreopsis flowers contain a class of pigments called anthochlors, which are not only pH sensitive, but also act as nectar guides, helping bugs like honeybees to find the nectar within the flower. This is because the pigments absorb UV light, which is invisible to us, but honeybees actually have decent UV vision! And if you’re curious about the shades of color produced, this is the result of phenol groups on the anthochlor pigment molecules being converted into phenolates, which results in a shif