Flower color in dahlia is the result of accumulation of red anthocyanins, yellow anthochlors and colorless copigments, such flavones and flavonols in various ratios.
Of the 20,000 varieties of dahlia flowers, only 10 to 20 kinds are black in color. Their scientific analysis revealed that the black color comes from extra high levels of anthocyanins. These pigments also give orange and red dahlias their colors, albeit at lower concentrations.
Single-flowered dahlias attract pollinators such as small copper butterflies, bees and bumblebees. Dahlia with double flowers such as ‘Cactus’ and ‘Pompom’ have been bred so that most, or all, of the reproductive parts of the flower have been converted into extra petals. They are of little or no use to insects.
The bloom in today’s photo is an ornamental dahlia ‘Parkfeuer’ (Dahlia hybrida).