The flavonoids are all structurally derived from the parent substance
flavone, which occurs as a white mealy farina on Primula plants, and all
share a number of properties in common. Some ten classes of flavonoid
are recognized (Table 2.7) and these different classes will be considered
in more detail in subsequent sections. In this section, general procedures
of identification are discussed and methods for distinguishing the
different classes are outlined.