Most plants have two-stage sexual reproduction {generation alternation} {alternation of generations}|. First is gametophyte stage and then sporophyte stage. Bacteria and blue-green algae do not have generation alternation.
In first stage {gametophyte stage}|, male sex organ makes haploid sperm, and female sex organ makes haploid eggs. Eggs and sperms unite to make zygotes. Zygotes divide to form diploid cells.
In second stage {sporophyte stage}|, plant cells make sporangia, which produce haploid spores by meiosis. Haploid spores undergo mitosis to make haploid sperm and eggs for gametophyte stage.
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Date Modified: 2022.0225