what is the pigment in hibiscus?
Hibiscus flowers bear pigments of three types: carotenoids, anthocyanins, and flavonols. The exact pigments (all three of those types are actually sizeable families of similar chemicals) and the exact proportions depend on the color of the particular flower: there are literally several hundred species in the genus Hibiscus, and they come in all shades of red, pink, yellow, and orange. Carotenoids are oil-soluble, fairly stable pigments that come in all shades of red, orange, and yellow. Anthocyanins are water-soluble and significantly less stable: they're responsible for the blues, pinks, purples, and reds, and in high concentrations can produce colors so dark as to look black. Flavonols are the least vivid of the pigments: they produce pale pastel yellows, cream colors, and off-whites. (Plain white flowers usually have no visible pigment at all.) Flavonols actually do most of their color absorption in the UV spectrum: they're the plant equivalent of the melanin in human skin, keeping them from getting sunburnt.
