[Henderson's] n. the reproductive structure of angiosperms (Anthophyta q.v.), being derived evolutionarily from a leafy shoot in which leaves have become modified into petals, sepals and calyx, and into the car­pels and stamens in which the gametes are formed. Although flowers can take many different forms, they can all be represented by concentric whorls of different parts inserted on a base (the receptacle). The outermost whorl of sepals (often green) forms the calyx, inside that is a whorl of often brightly coloured petals, next is a ring of stamens (the male reproductive organs), and in the centre are the carpels (the female reproductive organs). see Fig. 18.