The Plant Kingdom: Seed Plants

1. The Plant Kingdom:Seed Plants Chapter 28

2. Learning Objective 1 • Compare the features of gymnosperms and angiosperms

3. Two Groups of Seed Plants • Gymnosperms • seeds are totally exposed or borne on the scales of cone • ovary wall does not surround the ovules • Angiosperms • flowering plants • produce seeds within a fruit (a mature ovary)

4. Gymnosperm and Angiosperm Evolution

5. Gymnosperms Angiosperms Gnetophytes Ginkgoes Conifers Cycads Evolution of flowering plants Evolution of seeds Fig. 28-2, p. 602

6. KEY CONCEPTS • Seed plants include gymnosperms and angiosperms

7. Learning Objective 2 • Trace the steps in the life cycle of a pine • Compare its sporophyte and gametophyte generations

8. Conifers

9. Gymnosperms Angiosperms Gnetophytes Ginkgoes Conifers Cycads Fig. 28-3 (1), p. 603

10. Fig. 28-3 (a-c), p. 603

11. Pine Life Cycle 1 • Pine tree • a mature sporophyte • Pine gametophytes • extremely small • nutritionally dependent on sporophyte generation

12. Pine Life Cycle 2 • Pine is heterosporous • produces microspores and megaspores in separate cones • Male cones produce microspores that develop into pollen grains (immature male gametophytes) • carried by air currents to female cones

13. Pine Life Cycle 3 • Female cones produce megaspores • One of each four megaspores (meiosis) develops into a female gametophyte • within an ovule (megasporangium)

14. Pine Life Cycle 4 • Pollination • transfer of pollen to female cones • Pollen tube • grows through megasporangium to egg within archegonium • After fertilization • zygote develops into embryo encased inside seed adapted for wind dispersal

15. Pine Life Cycle

16. Each scale bears two microsporangia Microsporangium 2 Microspores, each of which develops into a pollen grain Scale from a male cone Pollen grains are transferred to the female cone by wind 3 3 Male cone 4 Scale from a female cone Female gametophyte Megasporangium Each scale bears two ovules (megasporangia) Megaspore Growing pollen tube Ovule HAPLOID (n) GAMETOPHYTE GENERATION Meiosis Fertilization Immature female cone DIPLOID (2n) SPOROPHYTE GENERATION Zygote 5 Second sperm nucleus Papery wings Sperm nucleus united with egg nucleus Pollen tube Seed coat Male cones (pollen cones) 1 6 Mature female cone (seed cone) Embryo Two seeds on the upper surface of the scale Female gametophyte (nutritive tissue) Newly germinated seedling Pine (mature sporophyte) Fig. 28-4, p. 604

17. Insert “Pine life cycle” pine_life_cycle.swf

18. Learning Objective 3 • What features distinguish gymnosperms from bryophytes and ferns?

19. Gymnosperms • Are vascular plants • unlike bryophytes • Produce seeds • unlike bryophytes and ferns • Produce wind-borne pollen grains • unlike ferns and other seedless vascular plants

20. KEY CONCEPTS • Gymnosperms produce exposed seeds, usually in cones borne on the sporophytes

21. Learning Objective 4 • What are the four phyla of gymnosperms?

22. Conifers(Phylum Coniferophyta) • Largest phylum of gymnosperms • Woody plants that bear needles (leaves that are usually evergreen) • produce seeds in cones • Most are monoecious • have male and female reproductive parts in separate cones on same plant

23. Male and Female Cones

24. KEY CONCEPTS • Conifers are the most diverse and numerous of the four living gymnosperm phyla

25. Cycads(Phylum Cycadophyta) • Palmlike or fernlike in appearance • Are dioecious • have male and female reproductive structures on separate plants • but reproduce with pollen and seeds in conelike structures

26. Cycads

27. Gymnosperms Angiosperms Gnetophytes Ginkgoes Conifers Cycads Fig. 28-6 (1), p. 605

28. Female strobilus (seed cone) Fig. 28-6a, p. 605

29. Fig. 28-6b, p. 605

30. Phylum Ginkgophyta • Ginkgo biloba • only surviving species in phylum • deciduous, dioecious tree • Female ginkgo produces fleshy seeds directly on branches

31. Ginkgo

32. Gymnosperms Angiosperms Gnetophytes Ginkgoes Conifers Cycads Fig. 28-7 (1), p. 606

33. Fig. 28-7a, p. 606

34. Fig. 28-7b, p. 606

35. Gnetophytes(Phylum Gnetophyta) • Share some traits with angiosperms

36. Gymnosperms Angiosperms Gnetophytes Ginkgoes Conifers Cycads Fig. 28-8 (1), p. 607

37. Gnetophytes

38. Learning Objective 5 • What features distinguish flowering plants from other plants?

39. Flowering Plants • Angiosperms (phylum Anthophyta) • Vascular plants that produce flowers and seeds enclosed within a fruit • Most diverse and successful plant group

40. Flowering Plants

41. Flowering Plants • Flower • sepals, petals, stamens,carpels • functions in sexual reproduction • Ovules enclosed within ovary • unlike gymnosperms • After fertilization • ovules become seeds • ovary develops into fruit

42. Floral Structure

43. Fig. 28-10a, p. 609

44. Female floral parts Male floral parts Pollen grain (each will produce two sperm cells) Stigma PISTIL (consisting of one or more carpels) Style Anther STAMEN Ovary Filament Ovules (each producing one egg cell) Petal Sepal Receptacle Peduncle Fig. 28-10b, p. 609

45. Parts of a Flower

46. Petals Sepals Fig. 28-11a, p. 610

47. Stamen Pistil Fig. 28-11b, p. 610

48. Simple and Compound Pistils

49. Stigma Ovules Style Ovary wall Ovary Fig. 28-12a, p. 611

50. One carpel Ovules Stigma Style Ovary wall Ovary Fig. 28-12b, p. 611