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GYMNOSPERMS

GYMNOSPERMS

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GYMNOSPERMS

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  1. GYMNOSPERMS “Naked Seeds”

  2. General Characteristics • Vascular • Alternation of generations • Dominant sporophyte • Reduced, dependent gametophyte • Produce uncovered seeds

  3. 4 Phyla of Gymnosperms • Cycads • Gingko • Conifers • Gnetophytes

  4. Cycads • Most diverse during age of dinosaurs • Only 100 living species • Palmlike appearance • Pollen-bearing and seed-bearing cones on different plants Strobilus of a “female” cycad

  5. Ginkgos • Diverse during age of dinosaurs • One surviving species, Ginkgo biloba • Deciduous trees are male or female • Seeds are completely exposed

  6. Share some traits with angiosperms Xylem Cone clusters resemble flower clusters Parts of life cycle more like angiosperms Gnetophytes

  7. Conifers • Widest known, largest number of living species • Woody trees or shrubs • Most are evergreen • Bear seeds on exposed cone scales • Most produce woody cones

  8. Pine Cones • Woody scales of a “pine cone” are the parts where megaspores formed and developed into female gametophytes • Male cones, where microspores and pollen are produced, are not woody

  9. Life cycle of typical conifer

  10. Animation: Pine Life Cycle CLICKTO PLAY

  11. Conifer Distribution • Reproduce more slowly than angiosperms; at competitive disadvantage in many habitats • Still dominate in far north, at higher elevations, and in certain parts of southern hemisphere