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Ch. 29 Plant Diversity I: The Colonization of Land

Ch. 29 Plant Diversity I: The Colonization of Land. Plant evolution A. Four main groups of extant plants:. bryophytes (mosses) -Mosses -Liverworts -Hornworts . 2. pteridophytes (ferns) -Lycophytes -Ferns -Horsetail. 3. gymnosperms (pines and conifers).

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Ch. 29 Plant Diversity I: The Colonization of Land

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  1. Ch. 29 Plant Diversity I: The Colonization of Land

  2. Plant evolution • A. Four main groups of extant plants: • bryophytes (mosses) • -Mosses • -Liverworts • -Hornworts

  3. 2. pteridophytes (ferns) -Lycophytes -Ferns -Horsetail

  4. 3. gymnosperms (pines and conifers) 4. angiosperms (flowering plants) Dicots Monocots

  5. Plants are • 1. multicellular • 2. eukaryotic • 3. photosynthetic • 4. autotrophs • How did they colonize the land? • Vascular tissue: tubes that transport • water and food. • a. However, most bryophytes do not have • vascular tissue. • (What makes • them adapted • to land is their • reproductive • adaptations.)

  6. The Seed (360 MYA): • Plant embryo packaged along with food • supply and a protective coat.

  7. The Flower: (130 MYA) • a complex reproductive structure that holds • both male and female parts. The flower • holds the seeds in the ovaries.

  8. Colonization on land overview: • Algae  Bryophytes  Vascular Plants •  Seed  Flowers • Charophyceans: Green • algae (closest plant • ancestor) • Similarities between • charophyceans and • land plants: • a. Produce cellulose • in a similar way • b. Peroxisomes • c. Flagellated sperm

  9. Characteristics that separated land plants from • charophycean algae: • Apical meristem: region of cell division • at the tips of roots and shoots.

  10. Multicelluar, Dependent Embryos • (Embryophytes): Parental tissue provides • developing embryo with nutrients Embryos

  11. Alternation of Generations: • two multicellular body forms alternate, • each form producing the other. Sporophyte: diploid multicellular organism Gametophyte: haploid multicellular organism

  12. Antheridium: male Archegonium: female

  13. Life Cycle of Fern:

  14. Walled Spores produced in Sporangia: • Spores: haploid cells that grow into • multicellular gametophyte by mitosis. • -made from sporopollenin • -made in the sporangia (singular = • sporangium) • -made from the “spore mother cells” • Multicellular Gametangia: gametophyte • a. produce the haploid gametes • b. Female: archegonia - egg • c. Male: antheridia – sperm with flagella

  15. Other adaptations to land: • Water conservation: • Cuticle: waxy polymer protects the • plant from microbial attack and acts as • waterproofing, preventing excess water • losss. • Stomata: Open for exchange of CO2 • and oxygen; close to minimize water • loss in hot, dry weather.

  16. Water transport: • Roots, stems, and leaves have vascular • tissues (tube system). -Xylem: tubes that carry water and minerals up from the roots. -Phloem: tubes that distribute sugars, amino acids, and other organic molecules throughout the plant.

  17. Secondary Compounds: alkaloids, • terpenes, tannins, flavonoids. • -toxic to defend against hervibores • -flavonoids absorb UV radiation • -human use: alkaloid quinine is used to • help prevent malaria

  18. II. The Origin of Land Plants • Land plants evolved from green algae • (probably charophycean) over 500 MYA. • Evidence: • Homologous chloroplast (DNA analysis) • Homologous cellulose walls (cellulose- • manufacturing rosettes) • Homologous peroxisomes (anti-photo- • respiration enzymes in peroxisomes) • Phragmoplasts (cell wall forms only • during cell division in charophyceans • and land plants) • Homologous sperm • Molecular systematics (rRNA, and • protein analysis)

  19. Three versions of the plant kingdom: • 1. Kingdom Plantae • 2. Kingdom Streptophyta • 3. Kingdom Viridiplantae

  20. III. Bryophytes: • Phylums: Mosses, Liverworts, and • Hornworts • Gametophyte is the dominant generation • Flagellated sperm • Most have no vascular tissue • Short stature (no lignin)

  21. The Origin of Vascular Plants: Origin of • the pteridophytes, gymnosperms, and • angiosperms • Vascular plants differ from bryophytes: • 1. Vascular tissue • 2. Dominant sporophyte generation • 3. Independent sporophytes

  22. Pteridophytes: Seedless vascular plants • Lycophyta: “club moss” (not a moss) • Ferns B.Pteridophytes provide clues to the evolution of roots and leaves • Lycophyta have small leaves with only • one unbranched vein.

  23. Lycophyta: club “moss” have small leaves known as “microphylls.”

  24. Ferns have megaphylls which are larger leaves, made possible because of the higher branched vascular system.  Greater photosynthetic productivity

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