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Conifers

Conifers. BIOL 1407. Seed Plants. Vascular Tissue Produce seeds Dispersal of offspring Produce pollen Sperm transfer without water. Seed Plants. Sporophyte dominant Gametophytes Greatly reduced in size Dependent on sporophyte. Seed Plants. Heterosporous Megaspore

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Conifers

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  1. Conifers BIOL 1407

  2. Seed Plants • Vascular Tissue • Produce seeds • Dispersal of offspring • Produce pollen • Sperm transfer without water

  3. Seed Plants • Sporophyte dominant • Gametophytes • Greatly reduced in size • Dependent on sporophyte

  4. Seed Plants • Heterosporous • Megaspore • Grows into female gametophyte  eggs • Microspore • Grows into male gametophyte  sperm • Photo Credit for Ovulate Cone: Dr. Stephen Bostic, ACC • Circled area: Ovule

  5. Pollen Production • Pollen cones have microsporophylls • Each microsporophyll has microsporangia • Photo Credit for Immature Male Pine Cones: Menchi, Wikimedia Commons

  6. Pollen Production • Meiosis occurs within microsporangia  microspores • Photo Credit for Staminate Cone: Dr. Stephen Bostic, ACC • Microsporangium circled in red • Microsporophyll at tip of yellow pointer • Microspores circled in pink

  7. Pollen Production • Microspores grow into male gametophytes • Male gametophyte = pollen grain

  8. Pollination • Pollen is released • Travels from male to female • Pollination occurs when pollen grain lands on female • http://www.youtube.com/watch?v=Bwl4g48-uIE

  9. Pollen Germination • After landing  pollen coat breaks open • 1 cell produces pollen tube • Photo Credit: Dr. David Byres, Florida Community College at Jacksonville

  10. Pollen Germination • A different cell produces 2 sperm cells by mitosis • They will move down pollen tube as it grows • Photo Credit: Dr. David Byres, Florida Community College at Jacksonville

  11. Pollen Germination • Pollen tube digests its way through female tissues to reach the egg

  12. Ovules • Ovulate cones have megasporophylls • Each megasporophyll has ovules containing megasporangia • Photo Credit for Immature Female Ponderosa Pine Cones: Susan McDougall @ USDA-NRCS PLANTS Database

  13. Ovules • Meiosis occurs within megasporangium  forms 1 megaspore and 3 haploid nuclei (degenerate) • Photo Credit: Dr. Stephen Bostic, ACC • Megasporangium circled in red • Megasporophyll at tip of yellow pointer

  14. Ovules • Megaspore grows into female gametophyte • Female gametophyte makes 1-2 eggs by mitosis

  15. Ovules • Integuments surround female gametophyte • Micropyle  lets pollen reach female gametophyte

  16. Ovules  Seeds • Integuments  seed coat • Female gametophyte  food supply • Fertilized egg  embryo

  17. Seeds • Dispersed by: • Wind • Animals • Water • Mechanical • Photo Credit for Pitch Pine Seeds: Steve Hurst @ USDA-NRCS PLANTS Database

  18. Types of Seed Plants • Gymnosperms • Naked Seeds • Not enclosed in ovaries • No fruits or flowers

  19. Types of Seed Plants • Angiosperms • Flowering Plants • Seeds enclosed in ovaries • Fruits and flowers

  20. Modern Gymnosperms • Conifers • Oldest living plants • Largest living plants • Widespread • Reproductive structure: Cones

  21. Modern Gymnosperms • Cycads • Wiry leaves • “Sago palms” • Ginkgos • Deciduous trees • One species • Herbal supplement

  22. Modern Gymnosperms • Gnetophytes • Ephedra (Mormon tea) • Welwitschia

  23. The End Unless otherwise specified, all images in this presentation came from: Campbell, et al. 2008. Biology, 8th ed. Pearson Benjamin Cummings.

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