I noticed some blue roses today.  These are very unusual as there have been no naturally blue roses apart from white roses which have been dyed.
For years breeders have crossed different colours of roses in an effort to create a blue rose. But rose petals lack the enzyme needed to create a blue pigment and the breeders were unsuccessful until they took the delphinidin gene which creates the blue colour from a petunia. They then inserted it into a mauve rose called the Cardinal de Richelieu and eventually got a blue rose.  Even so there are no true blue roses as they all appear to have a mauve tinge and the buds of these roses are pink.