The two reproductive whorls of a flower are the androecium and the gynoecium. The androecium is the male reproductive whorl made up of stamens; each stamen has an anther that produces pollen grains (which contain the male gametes). The gynoecium (pistil) is the female reproductive whorl made up of one or more carpels; each carpel has an ovary containing ovules (which contain the female gamete, the egg), a style and a stigma that receives the pollen.

Microsporogenesis is the process of formation of microspores (pollen grains) from a microspore mother cell (pollen mother cell) through meiosis; each diploid mother cell gives four haploid microspores arranged in a tetrad. A mature pollen grain has a two-layered wall: an outer hard exine made of sporopollenin (very resistant) with germ pores, and an inner thin intine of cellulose and pectin. Inside, a mature pollen grain is two-celled, having a larger vegetative cell (with food and a tube nucleus) and a smaller generative cell that later forms two male gametes.

A typical mature embryo sac (female gametophyte) is 7-celled and 8-nucleate. At the micropylar end there is the egg apparatus consisting of one egg cell and two synergids (with special thickenings called filiform apparatus). At the chalazal end there are three antipodal cells. In the centre there is a large central cell containing two polar nuclei. Thus, although there are 8 nuclei, there are only 7 cells because the central cell has two nuclei.