The carples of a flower may be separate or fused into a single structure. The female part of the flower is also referred to as a pistil. A pistil may consist of a single carpel or a group of fused carpels. The egg and polar nuclei participate directly in fertilization, and, following fertilization, the ovule develops into a seed and the ovary into a fruit. Flowering plants have an alternation of generations in which the sporophyte generation is larger and nutritionally independent and the gametophyte generation is microscopic in size and nutritionally dependent on the sporophyte.
Sexual reproduction occurs in the flower.
Each young ovule within an ovary contains a megasporocyte that undergoes meiosis to produce four haploid megaspores. Three of these usually disintegrate, and one divides mitotically and develops into a female gametophyte, also called and embryo sac. The embryo sac contains seven cells with eight haploid nuclei. Six of these cells including the egg cell, contain a single nucleus each , and a central cell has two nuclei, called polar nuclei. Each pollen sac, or microsporangium, of the anther contains numberous microsporocytes, each of which undergoes meiosis to form four haploid microspores.