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Chapter 26

Chapter 26. The Plant Kingdom: Seedless Plants. Environmental challenges of living on land required evolution of adaptations Anatomical Physiological Reproductive. Examples of adaptations Cuticle to prevent water loss Stomata for photosynthesis Alternation of generations Gametophyte

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Chapter 26

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  1. Chapter 26 The Plant Kingdom: Seedless Plants

  2. Environmental challenges of living on land required evolution of adaptations • Anatomical • Physiological • Reproductive

  3. Examples of adaptations • Cuticle to prevent water loss • Stomata for photosynthesis • Alternation of generations • Gametophyte • Sporophyte

  4. Basicplant life cycle

  5. Generalized reproductive structures of algae and plants

  6. Alternation of generations, cont. • Gametophyte produces gametes by mitosis • Gametes fuse to form zygote • Zygote develops into embryo

  7. Alternation of generations, cont. • Mature sporophyte develops from embryo, producing sporogenous cells • Sporogenous cells undergo meiosis to form spores

  8. Examples of adaptations, cont. • Gametangia protect gametes • Antheridia • Archegonia • Xylem conducts water and sugar nutrients • Phloem conducts dissolved sugar

  9. Plant gametangia

  10. Plants are probably descended from charophytes • Both have similar biochemical characteristics • Same photosynthetic pigments • Same cell wall components • Same carbohydrate storage material • Similarities in fundamental processes

  11. Plant evolution

  12. Features distinguishing bryophytes from green algae and other plants • Bryophytes have cuticle, stomata, etc. • Bryophytes are non-vascular and do not have xylem or phloem • Bryophytes have a dominant gametophyte generation

  13. The three phyla of bryophytes • Phylum Bryophyta (gametophytes grow from protonema) • Phylum Hepaticophyta (some have gametophytes that are thalli) • Phylum Anthocerotophyta (thalloid gametophytes)

  14. The life cycle of mosses • Green moss gametophyte bears archegonia and/or antheridia • During fertilization, sperm cell fuses with egg cell in archegonium • Zygote develops into embryo • Embryo develops into moss sporophyte

  15. Life cycle of mosses

  16. The life cycle of mosses, cont. • Moss sporophyte is attached to gametophyte • Meiosis occurs in capsule of sporophyte to produce spores • When spore germinates, it germinates into a protonema that forms buds

  17. Life cycle of Marchantia polymorpha

  18. Features distinguishing ferns and other seedless vascular plants from algae and bryophytes • Ferns and fern allies have adaptations including • Vascular tissues • A dominant sporophyte generation

  19. Evolution of microphylls and megaphylls

  20. The four phyla of seedless vascular plants • Phylum Polypodiophyta • Phylum Psilotophyta • Phlylum Equisetophyta • Phylum Lycophyta

  21. The life cycle of ferns • Fern sporophytes have megaphylls • Their fronds bear sporangia in clusters (sori) • Meiosis in sporangia produces haploid spores • Prothalli develop from these and bear both archegonia and antheridia

  22. Life cycle of ferns

  23. Generalized life cycles of homosporous and heterosporous plants • Homospory • Bryophytes, whisk ferns, horsetails, most club mosses, and most ferns • Spores give rise to gametophyte plants producing both egg and sperm cells

  24. Generalized life cycles of homosporous and heterosporous plants, cont. • Heterospory • Some clubmosses, some ferns, and all seed plants • Microspores give rise to male gametophytes • Megaspores give rise to female gametophytes

  25. Basic life cycle of heterosporous plants

  26. Life cycle of Selaginella

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