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Seeds

Seeds. What terrestrial adaptations led to the success of seed plants? Gametophyte generation is even more reduced!. First seed plants. Gymnosperm: conifers vascular heterospory male vs. female gametophytes seeds naked seeds (no fruit) pollen contain male gametophyte

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Seeds

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  1. Seeds • What terrestrial adaptations led to the success of seed plants? • Gametophyte generation is even more reduced!

  2. First seed plants • Gymnosperm: conifers • vascular • heterospory • male vs. female gametophytes • seeds • naked seeds (no fruit) • pollen • contain male gametophyte • life cycle dominated by sporophyte stage • coniferous trees you are familiar with are diploid • reduced (microscopic) gametophyte • reduction of gametophyte protects delicate egg & embryo in protective sporophyte • protected from drought & UV radiation

  3. Spores in brypohytes and mosses resist environmental changes • Seeds replace spore’s role of dispersing the species. • Spores are retained within the sporangia • Pollen frees sperm from water

  4. Gymnosperms • What does gymnospem mean? • Naked seeds • How are the needle shaped leaves of Coniferophyta adapted to dry conditions? • Thicker cuticle, stomata in pits

  5. Coniferophyta Examples…

  6. Gymnosperm: conifers

  7. Cones & naked seeds

  8. sporangium & pollen male male (pollen) cones female female cones pine embryo

  9. Pollen • Pollen eliminated the requirement for water for fertilization • spread through wind & animal

  10. Pine ovulate cone ovules

  11. Ovule from ovulate cone

  12. Mature Ovule Just Before Fertilization

  13. Fertilization

  14. Fertilization

  15. Pine staminate cone Pollen Pollen sac

  16. Germinating pollen grains Pollen grains

  17. Seed Dispersal in Coniferophyta

  18. Hypothetical phylogeny of Seed Plants

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