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Green Plants

Green Plants. Biol 366 Spring 2011. Tree of Life: The Big Picture. Bacteria. Archaea. Eukaryotes. now. membrane-bound nucleus, organelles, etc. >2 bya. >3.5 bya. ca. 4 bya. Fig. 7.1 from the text. Green plants share:. Chlorophylls a and b Starch storage

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Green Plants

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  1. Green Plants Biol 366 Spring 2011

  2. Tree of Life: The Big Picture Bacteria Archaea Eukaryotes now membrane-bound nucleus, organelles, etc. >2 bya >3.5 bya ca. 4 bya

  3. Fig. 7.1 from the text

  4. Green plants share: • Chlorophylls a and b • Starch storage • Stellate flagellar structure • Certain gene transfers from the chloroplast to the nucleus

  5. Green plant diversity: • > 300,000 species • Two major groups: 1) chlorophytes (marine and other green algae) and 2) streptophytes [freshwater green algae and embryophytes (= land plants)] • A major branch (clade) in the eukaryotic Tree of Life

  6. Fig. 7.2 from the text

  7. Chlorophytes: Fig. 7.3 from the text Basal streptophytes: Fig. 7.4 from the text

  8. Conjugation in Spirogyra Haplontic life cycle (haploid dominant or zygotic meiosis) The only diploid cell the zygote

  9. Charales Haplontic but some have multicellular gametangia (gamete-producing structures)

  10. Embryophytes (land plants) share: • Cuticle • Alternation of generations (multicellular sporophyte and multicellular gametophyte) • Multicellular gametangia (gamete-producing structures) • Multicellular sporangium (spore-producing structure) • Embryo (young sporophyte)

  11. Bryophytes • Hornworts, liverworts, mosses • Gametophyte-dominant • No vascular tissue (except conducting cells in a few mosses) • Separate male and female gametophytes • Sperm must swim to the egg, therefore need water for fertilization and therefore must remain small

  12. Fig. 7.5 from the text: liverworts, mosses and hornworts Fig. 7.6 from the text

  13. Hornwort sporophytes and gametophytes

  14. Liverwort thallus (gametophyte) showing air pores

  15. Liverwort Multicellular gametangia (male = antheridia)

  16. Liverwort Multicellular gametangia (female = archegonia) Oogamy Retention of zygote within the female gametophyte Multicellular embryo

  17. Capsule = sporangium of the sporophyte Moss male gametophyte (= antheridia)

  18. Tracheophytes (vascular plants) • Vascular tissue (tracheids) present • Include lycophytes, monilophytes (ferns, horsetails, whisk ferns), and spermatophytes (seed plants)

  19. Fig. 7.8 from the text

  20. Monilophytes and Lycophytes • Ferns, horsetails, quillworts, whisk-ferns, etc. • Independent gametophytes and sporophytes • Sperm must still swim to the egg • Most are homosporous; a few evolved heterospory • Many homosporous ferns have means of avoiding self-fertilization

  21. Lycophytes Isoetes (quillwort) Lycopodium and friends Selaginella

  22. Monilophytes (ferns, horsetails, whisk ferns) horsetails Whisk-fern (Psilotum) Ferns (Leptosporangia)

  23. Nutritionally independent sporophytes and gametophytes Sporophyte (2n) Gametophyte (1n) 1n spores

  24. Fig. 8.4 from the text Fern Life Cycle

  25. Spermatophytes(seed plants) • Secondary xylem (wood), heterospory, seeds • Includes gymnosperms and angiosperms

  26. Fig. 7.12 from the text

  27. Gymnosperms • Conifers, gingko, cycads, Gnetales • Heterosporous (male and female sporangia) • Sporophyte-dominant • Antheridia lost, replaced by pollen (= male gametophyte) • Archegonia present but reduced, embedded in nutritive tissue of the megasporangium (+ integument = ovule) • Bear seeds (= fertilized, embryo-containing, unopening ovule)

  28. Female cone with each scale bearing usually two ovules; directly exposed to pollen Male cones with each scale bearing two or more microsporangia

  29. pine pollen Section of female pine cone pine microsporangia

  30. Pine seedling—next sporophyte generation Pine seeds

  31. Angiosperms • “Dicotyledons”, monocotyledons • Heterosporous • Sporophyte-dominant • Pollen = male gametophyte • Archegonia lost; embryo sac = female gametophyte; ovules enclosed in carpels (indirect pollination) • Double fertilization produces zygote + primary endosperm nucleus

  32. Flower = a short, determinate shoot bearing highly modified leaves, some of which are fertile (i.e., bearing either microsporangia or megasporangia), with the megasporangia in carpels

  33. Fig. 4.17 from the text: Angiosperm life cycle

  34. Animal pollination syndromes

  35. Wind pollination

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