Chapter 29 and 30 - Plant Diversity

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Chapter 29 and 30 - Plant Diversity

  1. 1. PLANT DIVERSITYChapters 29 & 30
  2. 2. Definition of Plants• Multicellular• Eukaryotic• Photosynthetic• Autotrophic• Cell walls made of cellulose• Chlorophylls a and b
  3. 3. Plant Evolution
  4. 4. 4 Main Groups of Land Plants • Bryophytes – non vascular plants • Mosses, liverworts, hornworts • Pteridophytes - seedless vascular plants • Lycophytes, ferns, horsetails, whisk ferns • Gymnosperms – naked seed plants • Ginko, cycads, gnete, conifers • Angiosperms – flowering plants
  5. 5. Land Plant Evolution• Ancestral green algae• Aquatic plants: Charophyceans• Land plants: • Development of vascular tissue • Development of seeds • Development of flowering plants
  6. 6. Charophyceans• Closest relative of land plants• Algal group• Similarities with land plants • Rosette cellulose-synthesizing complexes • Located in plasma membranes • Peroxisomes • Flagellated sperm (some land plants)
  7. 7. Evidence of common ancestor withcharophycean algae• Homologous chloroplast• Homologous cellulose walls• Homologous peroxisomes• Homologous sperm• Molecular systematics • Chloroplast DNA • Ribosomal RNA
  8. 8. Adaptations of Land Plants• Apical meristems • Roots and shoots – growth• Multicellular, dependent embryos • “embryophytes” • Transfer of nutrients from parent• Alternation of generations • Sporophyte (diploid) and gametophyte (haploid)• Gametangia – gametes are produced within multicellular organ • Female – archegonia • Male - Antheridia• Walled spores – resist drying out• Cuticle – waxy covering, water conservation• Stomata – pores, water conservation• Vascular tissue – transport water and minerals
  9. 9. Apical meristems of plant shoots and roots
  10. 10. Embryos of Land Plants
  11. 11. Alternation of generations
  12. 12. Walled Spore
  13. 13. Gametangia: Gametes produced within multicellular gametangia Archegonium - female Antheridium - male egg sperm
  14. 14. Cuticle of a stem: Prevents drying out
  15. 15. Vascular Tissue: Xylem and Phloem Xylem (water) Phloem (food)
  16. 16. Development of Alternation of Generations • Delay in meiosis until one or more mitotic divisions of the zygote occurred • Result: multicellular, diploid sporophyte • Increases number of spores produced per zygote
  17. 17. What is the Plant Kingdom?
  18. 18. Bryophytes• Three phyla • Hepatophyta: liverworts • Anthocerophyta: hornworts • Bryophyta: mosses• Non-vascular• Earliest land plants• Gametophyte (haploid) is dominant form• Anchored by rhizoids• No true roots or leaves
  19. 19. Bryophytes
  20. 20. Life cycle of a moss
  21. 21. Moss life cycle gametophyte gametangia sporophyte Protonemata sporophyte spores (pre-gametophyte)
  22. 22. Sphagnum, or peat moss gametophyte sporophyte
  23. 23. Vascular Plants• Vascular plants have • Xylem – transports water • Phloem – transports food • Dominant sporophyte generation• First vascular plants were seedless• Three Groups • Seedless plants • Gymnosperms • Angiosperms
  24. 24. Seedless Vascular Plants• Two phyla • Lycophyta – lycophytes • Pterophyta – ferns, whisk ferns, horsetails• Most have true roots and leaves• Still require water for fertilization
  25. 25. Pteridophytes Club “moss” Whisk fern Horsetail Fern
  26. 26. Hypothesis for the development of leaves• Probably evolved from a flap of stem tissue • Stem had vascular tissue • Microphylls• Macrophylls – larger leaves with branched veins
  27. 27. Ferns
  28. 28. Life cycle of a fern
  29. 29. Fern sporophyll, a leaf specialized for spore production & sori
  30. 30. Sorus (sori): Clusters of sporangia – found on underside of leaves
  31. 31. Mature fern sporangium – releasing spores
  32. 32. Fern gametophyte
  33. 33. Archegonia of fern Flagellated sperm from antheridium fertilize eggs in archegonium zygote
  34. 34. Fern sporophytes
  35. 35. Evolution of Seed Plants• Reduction of gametophyte continued• Seeds – important means of dispersal• Pollen – eliminated water requirement for fertilization • Pollination• Two clades • Gymnosperms • Angiosperms
  36. 36. Gametophyte/ Sporophyte Relationships• Seed plants: further reduced gametophyte• Female gametophyte and embryo protected by parental sporophyte
  37. 37. Seed Development• Fertilization initiates the transformation from ovule to seed • Sporophyte embryo • Food supply • Protective coat
  38. 38. Seed Dispersal• Seeds have adaptations for dispersal• Wind• Water• Animal
  39. 39. Gymnosperms• Four phyla • Ginko • Cycads • Gnetophytes • Conifers• Naked seed – no fruit (ovary)• Seeds develop on surface of sporophylls• Evolved before angiosperms
  40. 40. Phylum Coniferophyta Douglas fir Sequoia
  41. 41. Phylum Coniferophyta: Frasier Fir
  42. 42. Characteristics of Conifers• Cone: reproductive structure • Cluster of sporophylls • Female cones: produce ovules - “pine cones” • Male cones: produce pollen• Seed develops from fertilized ovule – scale of cone• Dominate in areas with short growing season • High latitude or altitude• Most are evergreens• Some have needle-shaped leaves • Adapted for dry conditions • Thick cuticle
  43. 43. Life cycle of a pine
  44. 44. Pollen cone (male) – produces pollen Pine pollen
  45. 45. Pine embryo Embryo (new sporophyte)
  46. 46. Angiosperms: Flowering Plants Major Clades:
  47. 47. Phylum Anthophyta: Angiosperms• Vascular seed plants• Reproductive structures: flowers, fruits• Most diverse group of plants today• 2 groups Monocots Dicots # Petals Multiples of 3 Multiples of 4 or 5 # Cotyledons 1 2 Vascular bundles Scattered Circle Root Fibrous Tap root
  48. 48. Xylem cells in Angiosperms• Trachids • Support • Water transport• Fiber ** • Support• Vessel element ** • More efficient** Evolutionary adaptations of angiosperms
  49. 49. Flower Structure: Reproductive Adaptation of Angiosperms
  50. 50. Life cycle of an angiosperm
  51. 51. Fruit and Seed Dispersal
  52. 52. Flower-pollinator relationships

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