The male parts of the flower are sometimes collectively called the androecium . The innermost layer of a flower is the female portion, which consists of three parts. A pistil contains one or more carpels , which enclose one or more ovules. The enlarged ovary is at the base, which contains ovules , which eventually become mature seeds. The female parts of the flower are sometimes collectively called the gynoecium .
Female gametophytes develop in megasporangia, while male gametophytes develop in microsporangia.
These tissues are haploid. In the megasporangium, the megasporocyte divides to produce 4 haploid megaspores. Three of those break down, and the other one divides several times to produce 8 nuclei. In the microsporangium, the microsporocytes divide meiotically to produce microspores. When a pollen grain lands on the stigma, a pollen tube develops which grows downward until it reaches the ovary.