Ovule

An ovule is a structure in seed plants that contains the female gametophyte and can develop into a seed after fertilization.

Megasporangium: A plant spore-producing structure in which megaspores form. The ovule’s nucellus is a megasporangium where the megaspore develops.
Pollination: The transfer of pollen to a receptive part of a seed plant. Pollen must reach the flower’s stigma before a pollen tube can approach an ovule.
Plant breeding: The deliberate selection and crossing of plants to produce desired inherited traits. Successful crosses depend on fertilization and seed formation in ovules.
Gymnosperm: A seed plant whose ovules are not enclosed within an ovary. Its exposed ovules contrast with the ovules enclosed by flowering-plant ovaries.
Megaspore: A haploid spore that develops into the female gametophyte in seed plants. One megaspore usually survives inside the ovule and gives rise to its gametophyte.
Pollen tube: A tubular extension of a pollen grain that delivers sperm cells to the female gametophyte. It grows toward the ovule and carries sperm cells to the embryo sac.
Apomixis: Asexual seed formation that bypasses fertilization or meiosis, depending on the form. It produces seeds without the ordinary fertilization pathway inside an ovule.
Angiosperm: A flowering plant whose seeds develop from ovules enclosed in an ovary. Its enclosed ovules distinguish flowering-plant reproduction from gymnosperm reproduction.
Embryo sac: The female gametophyte of a flowering plant, typically containing an egg cell and central cell. This is the gametophyte housed within a flowering plant’s ovule.
Double fertilization: The flowering-plant process in which one sperm fertilizes the egg and another fuses with the central cell. It produces both the embryo and endosperm within the fertilized ovule.

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