Development of the gametophytesHaploid microspores develop from microsporocytes in the anthers and give rise to pollen grains containing two cells: the tube cell and the generative cell. At about the time of pollination, the latter cell divides and produces two sperm. This three-celled pollen grain is the immature male gametophyte (microgametophyte). The female gametophyte, the megagametophyte, develops in the ovary at the same time the male gametophyte is developing in the anthers. While the process is exceedingly variable among taxa, about three-quarters of the flowering plants go through the following steps. One megasporocyte is contained in each of the young ovules within the ovaries in the flower buds. The ovule is attached by a stalk, the funiculus, to the placenta on the ovary wall and, at this stage,
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