Flower Colour

Abstract

Generally, light- and dark-coloured flowers possess low- and high pigment levels, respectively (Swain, 1965; De Loose, 1970; Yasuda, 1971; Khokhar et al., 1982; Dorn and Bloom, 1984; Arisumi et al., 1985; Nieuwhof et al., 1989; Smith, 1990b). As already has been discussed, at least two different classes of pigments — namely the lipid-soluble chlorophylls and carotenoids — and the water-soluble flavonoids determine the colour of flowers. The flavonoids are the most common flower pigments. With respect to colour, anthocyanins are much more important than flavones and flavonols. When anthocyanins occur together with water-soluble yellow pigments (e.g., chalcones and aurones) their colours mix. When anthocyanins and lipid-soluble yellow pigments (e.g., carotenes and xanthophylls) co-occur, the resulting flower colour is often more brown than orange. This might be explained by compartmentation; the water-soluble yellow pigments as well as the anthocyanins are present in the cell vacuole, the carotenoids — on the other hand — are located in the plastids (Harborne, 1976). The whole range of flower colours from pink, orange and scarlet to mauve, violet and blue is realized by these two classes of pigments.