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Evolution of the Seed Plant

Evolution of the Seed Plant. 3 Important Adaptations. Reduction of gametophyte Advent of the seed Evolution of pollen. In seed plants, the miniature female gametophytes develop from spores that are retained with the sporangia of the parental sporophyte.

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Evolution of the Seed Plant

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  1. Evolution of the Seed Plant

  2. 3 Important Adaptations • Reduction of gametophyte • Advent of the seed • Evolution of pollen

  3. In seed plants, the miniature female gametophytes develop from spores that are retained with the sporangia of the parental sporophyte

  4. Advantage- female gametophytes do not have to cope with many environmental stresses. These as well as the young embryos are sheltered from drought and harmful UV radiation by being enclosed in moist reproductive tissues of the parental sporophyte generation.

  5. Seeds become an important means of dispersing offspring

  6. A seed is complex multicellular reproductive structure (spore-a single cell)

  7. A seed: • Sporophyte embryo • Food supply • Protective coat

  8. All seeds plants are heterosporous FEMALE MALE

  9. In seed plants layers of sporophyte tissues called INTEGUMENTS envelop the mega sporangium. The whole structure, integument, is called an ovule.

  10. A female gametophyte develops within a megaspore and produces one or more eggs. If an egg cell is fertilized by a sperm, the zygote develops into a sporophyte embryo. The entire ovule develops into a seed.

  11. Seeds may remain dormant for years.

  12. Pollen eliminates the need for water in fertilization

  13. Microspores develop into pollen grains-which mature to male gametophytes of seed plants. Pollen is protected by sporopollen. Pollen Cone

  14. Pollination is the transfer of pollen to ovules

  15. When pollen lands in the vicinity of an ovule, it will elongate a tube that discharges on or more sperm into the female gametophyte.

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