Ultraviolet photo of a Ranunculus bulbosus (Bulbous buttercup) flower. In UV the flower has a much darker centre. The stamens and pistils both appear quite dark. The bases of the petals also have strong dark markings. It is thought these markings may help guide insects (which can see UV light) to where the nectar / pollen is located.
White balance and exposure adjusted in ACR to brighten background