The pigments known as flavonoids can be found in a wide range of plant parts, including flowers, fruits, and seeds. Flavonoids belong to the class of phenolic compounds. Plants contain secondary metabolites that can be broken down into the following six subgroups: chalcones, flavones, flavonols, flavandiols, anthocyanins, and proanthocyanidins or condensed tannins. Flavones are the most common of these secondary metabolites. Some species also contain aurones.