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Seed-bearing Plants

0. Seed-bearing Plants. 0. 0. Land Plants fall into two major groups. Non vascular Vascular. 0. Vascular Plants. Some are seedless Others produce seed. 0. Seed-bearing Vascular Plants fall into two major categories. Angiosperms. Gymnosperms. 0.

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Seed-bearing Plants

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  1. 0 Seed-bearingPlants

  2. 0

  3. 0 Land Plants fall into two major groups • Non vascular • Vascular

  4. 0 Vascular Plants • Some are seedless • Others produce seed

  5. 0 Seed-bearing Vascular Plants fall into two major categories Angiosperms Gymnosperms

  6. 0 Seed-bearing Vascular Plants fall into two major categories • Gymnosperm – seeds naked on surface of sporophyll • Angiosperm – seeds enclosed in a ripened ovary

  7. 0 Seed-bearing plants also produce pollen

  8. 0 Living Gymnosperms Cycads Conifers Ginkgoes Gnetophytes

  9. 0 Cycads Appeared on Earth 250 MYA • Reached their greatest abundance and diversity during the Jurassic • Declined sharply during the Cretaceous radiation of the angiosperms.

  10. Global Distribution of Cycads is Tropical

  11. 0 Mexican Cycads Dioon Ceratozamia

  12. 0 Australian Cycads Macrozamia Macrozamia

  13. 0 African Cycads Encephalartos Stangeria

  14. 0 Only Cycad Native to the US Zamia pumila

  15. 0 Cycads – Vegetative Characteristics Encephalartos in Africa

  16. 0 Cycad Stems • Columnar • Little branching • Not very woody

  17. Produced in crowns at tip of stem Pinnately compound 0 Cycad Leaves

  18. 0 Certain roots in Cycads grow toward the soil surface Corraloid Roots

  19. 0 A Closer Look at Coralloid Roots • Grow upward near soil surface • Branch to form masses • Root cortex inhabited by Cyanobacteria(carry out nitrogen fixation)

  20. 0 Cycads – Reproductive Structures

  21. Cycads produce pollen and seeds in cones • Cones develop at apex of stem

  22. 0 All Cycads are Dioecious • Individual plants produce either pollen cones or seed cones Pollen Cone Seed Cone Cycas revoluta

  23. 0 Many Cycads are Pollinated by Insects • Only a few cycad species studied • Weevils and oldest known bee genus (Trigona) • Usually pollinators mate and lay eggs within female cone • All cones except Stangeria produce heat. Thought to volatilize pollinator attractants • Hence insect pollination may predate flowering plants Trigona weevils

  24. The Gnetophytes Ephedra Gnetum Welwitschia

  25. 0 Ephedra is a desert shrub

  26. Ephedra is distributed in arid regions of the world 50 species 39 species monotypic

  27. Ephedra contains Ephedrine http://www.anephedraattorneyforyou.com/

  28. Pseudoephedrine is a Synthetic Version of Ephedrine

  29. Gnetum is a tropical vine or small tree

  30. Gnetum occurs in the tropics 50 species 39 species monotypic

  31. Welwitschia is a bizarre plant of an extremely arid environment

  32. Welwitschia occurs only in the Namib Desert in South-West Africa 50 species 39 species monotypic

  33. Welwitschia forms a short stem and deep tap root

  34. Welwitschia produces only two adult leaves

  35. Welwitschia leaves grow from the base – leaves fray as they grow

  36. Ginkgo – The Maiden Hair Tree

  37. Today represented by a single species Once occurred in North American Forests Presently occurs naturally only in China 0 Ginkgo was a common forest tree in the geological past

  38. “Natural” trees may actually be plants cultivated at ancient Monasteries 0 Present Distribution of Ginkgo biloba

  39. Ginkgo is also widely cultivated

  40. 0 Ginkgo – Vegetative Characteristics

  41. Ginkgo is Deciduous

  42. Ginkgo is Deciduous

  43. Extensive branching Very woody 0 Ginkgo Stems

  44. 0 Ginkgo Stems long shoot spur shoot

  45. 0 Ginkgo Stems spur shoot long shoot

  46. Fan shaped Dichotomous branching veins 0 Ginkgo Leaves

  47. Leaf shape ranges from entire to bilobed

  48. Individual plants produce either pollen “cones” or seed “cones” Produced on spur shoots 0 All Ginkgo trees are Dioecious C Pollen “Cone” Seed “Cone”

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