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Chapter 8 Section 4

Chapter 8 Section 4

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Chapter 8 Section 4

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  1. Chapter 8 Section 4 Gymnosperms

  2. Gymnosperms • A seed plant that produces naked seeds • Not enclosed by a protective fruit • Many gymnosperms have needle-like or scale-like leaves, and deep-growing root systems • Oldest type of seed plant

  3. Cycads • Grow mainly in tropical and subtropical areas • Look like palm trees with cones • Cone can grow as large as a football

  4. Conifers • Cone-bearing • Largest and most diverse group of gymnosperms • Most keep their needles year round

  5. Ginkgoes • Only one species exists today, Ginkgo biloba • Chinese and Japanese cared for it in their gardens • Planted along city streets because they can tolerate air pollution

  6. Gnetophytes • Live in hot deserts and in tropical rain forests • Trees, shrubs, and vines

  7. Reproduction of Gymnosperms • Cones: reproductive structures in most gymnosperms • Males cones • Produce tiny grains of pollen (the male gametophyte) • Later become sperm cells • Female Cones • Ovule: female gametophyte • Contains egg cell • Develops into seed

  8. Gymnosperm Reproduction

  9. Pollination • Transfer of pollen from male reproductive structure to female reproductive structure • Wind often carries the pollen

  10. Fertilization • Once pollination occurs, the ovule closes and seals in the pollen • Sperm cell and egg cell areinside each ovule • The egg is fertilized and develops into the embryo

  11. Seed Development • Female cones remain on tree while seeds mature • Can take up to 2 years • Male cones usually fall off tree after they shed their pollen

  12. Seed Dispersal • When seeds mature, scales open • Wind shakes seed out of cone and carries them away • Only a few seeds will land in suitable place

  13. Page 275