. Elementary biology; an introduction to the science of life . Fig. 153. Alternation of generations in seed-bearing plants 6';«, the male gametophyte, or pollen tube ; m, the male gamete, a nucleus at end of pollen tube ; Gf, the female gametophyte, or embryo sac ; /, the female gamete, a nucleus in the embryo sac; e, the fertilized egg, in embryo sac ; 5]^, young sporophyte, the embryo in the seed ; 6V,, the mature sporophyte, a flower-bearing plant; jj, the large spore, giving rise to the female gametophyte. or the embryo sac. So., the small spores, or pollen grains, giving rise to the male
. Elementary biology; an introduction to the science of life . Fig. 153. Alternation of generations in seed-bearing plants 6';«, the male gametophyte, or pollen tube ; m, the male gamete, a nucleus at end of pollen tube ; Gf, the female gametophyte, or embryo sac ; /, the female gamete, a nucleus in the embryo sac; e, the fertilized egg, in embryo sac ; 5]^, young sporophyte, the embryo in the seed ; 6V,, the mature sporophyte, a flower-bearing plant; jj, the large spore, giving rise to the female gametophyte. or the embryo sac. So., the small spores, or pollen grains, giving rise to the male gametophyte. The spores always give rise to gametophytes, and the gametes (producing a fertilized egg) always give rise to sporophytes. Sporophytes alternate with gametophytes, generation after generation Our common seed plants are accordingly seen to be spowphytes, or spore-bearing plants. The alternation of generations of these plants is illustrated by the diagram in Fig. 153.
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Keywords: ., bookcentury1900, bookdecade1920, bookpublishe, booksubjectbiology
