Gentisin, found in yellow gentian (Gentiana lutea),
As a rule, the most brilliant of these yellow pigments are found in the largest quantities in the bark and wood of various species of tropical plants; although they are also present, in smaller amounts, in the blossoms of species growing in temperate zones.
The anthoxanthins are easily converted into anthocyanins, and vice versa, by the action of oxidizing and reducing enzymes which are commonly present in the tissues of the plants which develop the pigments.
THE PRODUCTION OF ORNAMENTAL PIGMENTS IN FLOWERS, ETC.
The breeding of flowering plants having blossoms of almost any desired color has become a commercial enterprise of large importance. The results which have been obtained, in many cases, have been made the object of scientific study of the genetics of color inheritance. These studies have developed certain interesting facts with reference to the chemistry of the development of these ornamental pigments, which may be briefly mentioned here.
In many of the plants which have been studied, the color of the flowers depends upon several different factors, as follows:
C, a chromogen (or color-producing substance) which is generally a flavone or xanthone glucoside, and which may be either yellow or colorless.
E, an enzyme which acts upon C, to produce a red pigment.