SUMMARY
Alternation of generations occurs in all plants. A haploid gametophyte generation produces gametes via mitosis. The union of gametes produces the diploid sporophyte generation, which in turn produces spores via meiosis. A fundamental difference that arose early in the evolution of land plants was relative dominance of the gametophyte and sporophyte. Bryophytes, the nonvascular seedless plants, have followed a path with a dominant gametophyte. All other plants, including the pterophytes, have a dominant sporophyte.

Activity
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