White flower colour is related to the absence or reduction of the anthocyanidin content. Unlike other colors, white colour is not induced by pigments. Several white plant tissues are principally equipped with the complete machinery for anthocyanin biosynthesis including the expression of regulatory genes. Nevertheless, they are unable to accumulate red or blue pigments, for example Dahlia ´Seattle´ petals showing a white tip. Several studies have revealed a further reduction of the anthocyanidin to colorless epicatechin by the enzyme anthocyanidin reductase (ANR).