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The Plant Kingdom

The Plant Kingdom. Origins 500- 475 MYA 10 Phyla 4 Basic lifecycles Green algae that evolved onto land Evolved becoming more terrestrial, independent from water Then coevolved with pollinators, dispersal. Tentative Phylogeny Fig 28.8. An overview of land plant evolution. Land plants.

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The Plant Kingdom

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  1. The Plant Kingdom • Origins 500- 475 MYA • 10 Phyla • 4 Basic lifecycles • Green algae that evolved onto land • Evolved becoming more terrestrial, independent from water • Then coevolved with pollinators, dispersal

  2. Tentative Phylogeny Fig 28.8

  3. An overview of land plant evolution Land plants Vascular plants Bryophytes (nonvascular plants) Seedless vascular plants Seed plants Mosses Hornworts Liverworts Angiosperms Gymnosperms Charophyceans Pterophyte (ferns, horsetails, whisk fern) Origin of seed plants (about 360 mya) Lycophytes (club mosses, spike mosses, quillworts) Origin of vascular plants (about 420 mya) Origin of land plants (about 475 mya) Ancestral green alga Figure 29.7

  4. Lab • Chara Lifecycle • Moss Lifecycle • Liverworts • Fern Lifecycle • Lycophytes

  5. Charophyceans- plant’s green algae ancestor Chara - 30 Coleochaete- 31 Modern examples of charophyceans

  6. Chara sp. (green algae)

  7. Chara Slide #30 Oogonia Antheridia

  8. Chara sp. Oogonia Antheridia

  9. Alternation of Generations • Separate multicellular haploid and diploid phases • (2n) Sporophyte make spores by meiosis • (n) Gametophyte makes gametes by mitosis • Sperm and egg (moss & fern) • Pollen and Ovule (gymnosperm & angiosperm) • The sporophyte and gametophyte are very different in morphology • Vascular tissues only appear in sporophyte phase • Sporophyte becomes more dominant in new plant groups • Charophyceans lack sporophyte phase

  10. Characteristics that Plants share with the green algae group Charophyceans • Autotrophic Multicellular Eukaryote • Have cell walls made of cellulose • Made by rosette cellulose-synthesizing complexes • 20-26% of wall material, closest match in algae • Chloroplast similarities • have chlorophyll a & b, use β-carotene as accessory • Thylakoids stacked in grana • Chloroplast DNA comparisons

  11. Characteristics that Plants share with the green algae group Charophyceans • Peroxisome enzymes • Cell plate formation by phragmoplast • Nuclear membrane breaks down during mitosis • Sperm ultrastructure - biflagellate • Gene sequences – rRNA, Cytoskeleton proteins

  12. Switch to sporophyte dominance

  13. What’s new in Mosses?( Derived Traits) • Spores / sporangia • Sporophyte phase • Upright growth on land • Cuticle • Multicellular gametangia

  14. The Bryophytes • Bryophytes are represented by three phyla: • Division Hepatophyta - liverworts • Division Anthocerophyta - hornworts • Division Bryophyta – mosses Liverworts and hornworts are believed to be more similar to what early plants were like.

  15. Bryophyte lifecycle: moss • Haploid dominant • No vascular tissues • Filamentous protonema stage • Swimming sperm • Disperse by spores • Dependent sporophyte • Dioecious gametophytes • No true leaves • Rhizoids, not roots

  16. Pteridophytesevolved over 400 MYA Seedless, Vascular plants (having Xylem & Phloem). Today represented by two phyla: Pterophyta: Ferns, Horsetails (Equisetum) Lycophyta: Club moss Cooksonia, an extinct plant over 400 million years old, is the earliest known vascular plant.

  17. Protonema

  18. Protonema - #32

  19. Moss Antheridia

  20. Antheridia on stalk

  21. Moss Antheridia # 33

  22. Moss Archegonia

  23. Moss Archegonia #34

  24. Moss Archegonia #34

  25. Moss Sporangia

  26. Moss Sporangia- 35

  27. Moss Sporangia- # 35

  28. An overview of land plant evolution Land plants Vascular plants Bryophytes (nonvascular plants) Seedless vascular plants Seed plants Mosses Hornworts Liverworts Angiosperms Gymnosperms Charophyceans Pterophyte (ferns, horsetails, whisk fern) Origin of seed plants (about 360 mya) Lycophytes (club mosses, spike mosses, quillworts) Origin of vascular plants (about 420 mya) Origin of land plants (about 475 mya) Ancestral green alga Figure 29.7

  29. Spores WALLED SPORES PRODUCED IN SPORANGIA Sporangium Longitudinal section of Sphagnum sporangium (LM) Sporophyte and sporangium of Sphagnum (a moss) Sporophyte Gametophyte MULTICELLULAR GAMETANGIA Female gametophyte Archegonium with egg Antheridium with sperm Archegonia and antheridia of Marchantia (a liverwort) Male gametophyte MULTICELLULAR, DEPENDENT EMBRYOS Embryo Maternal tissue 2 µm Embryo and placental transfer cell of Marchantia 10 µm Wall ingrowths Placental transfer cell

  30. Liverwort Gametophyte

  31. Female Gametophyte

  32. Liverwort Antheridia • Antheridia are on the upper surface of the “umbrellas”

  33. Liverwort Antheridia

  34. Liverwort Archegonia • Archegonia are on the undersides of the “umbrellas”

  35. Liverwort Archegonia

  36. Liverwort Archegonia - egg

  37. Liverwort Sporangia • On undersides- develop from archegonia

  38. Gemmae & cups

  39. Gemmae & cup

  40. An overview of land plant evolution Land plants Vascular plants Bryophytes (nonvascular plants) Seedless vascular plants Seed plants Mosses Hornworts Liverworts Angiosperms Gymnosperms Charophyceans Pterophyte (ferns, horsetails, whisk fern) Origin of seed plants (about 360 mya) Lycophytes (club mosses, spike mosses, quillworts) Origin of vascular plants (about 420 mya) Origin of land plants (about 475 mya) Ancestral green alga Figure 29.7

  41. Vascular tissue • Allows plants to grow taller • More support by lignified xylem tracheids • Can pull water up from soil • Can tolerate soil that is drier on the surface • Form parts of true leaves and roots. • Only found in diploid tissue • Lead to sporophyte dominance?

  42. Fern Lifecycle • Diploid dominate • Gametophyte still independent, short lived, • monoecious in fern (Pteridophyta) • dioecious in club “moss” (Lycophyta) • Spores disperse plant • Sporophyte perennial

  43. Pteridophytesevolved over 400 MYA Seedless, Vascular plants (having Xylem & Phloem). Today represented by two divisions: Pterophyta: Ferns, Horsetails (Equisetum) Lycophyta:Club moss Cooksonia, an extinct plant over 400 million years old, is the earliest known vascular plant.

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