Abstract
Almost flower colors of wild and cultivated plants are due to anthocyanins and/or carotenoids. On the other hand, several flower colors are expressed by other pigments. For example, the flower colors of nine family species, such as Portulaca, cactus, cockscomb and Mesembryanthemum belonging to the order Caryophyllales except for the family Caryophyllaceae and Molluginaceae, are due to betalain pigments. Thus, their red purple and yellow flower colors are expressed by betacyanins and betaxanthins, respectively. Anthochlors, chalcones and aurones, contribute to the yellow colors of carnation, Cosmos, Corylopsis, snapdragon and so on. Flavonols substituted 6- or 8-position by hydroxyl group such as gossypetin are named as yellow flavonols and express the yellow colors of some Centaurea and Hibiscus species. When much amount of common flavonol, quercetin, is present in the flowers, e.g. Clematis, it acts as yellow pigment. More recently, it was reported that the deep yellow flower colors of Camellia chrysantha are expressed by common quercetin glycosides together with aluminum ions.
