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The development of angiosperm gametophytes
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Now Pollen
Pollen grains are the immature male gametophytes
produced by flowers and trees, or more precisely, the seed plants. In seed
plants the seed and the pollen grain replaces the spores as a mode of
dispersing the offspring. All seed plants are heterosporous, meaning they have
two different types of sporangia to produce two types of spores: megasporongia
produce megaspores, which give rise to the female gametophytes, whereas the
microsporongia produce microspores, which give rise to male (sperm-containing)
gametophyte. Microspores develop into pollen grains, which in turn mature to
become the male gametophytes of seed plants.
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