CHAPTER 29 PLANT DIVERSITY I

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CHAPTER 29PLANT DIVERSITY I

• I. General Characteristics - multicellular
  eukaryotes that are photosynthetic cell walls of
  cellulose store excess carbohydrate as starch
  nearly all terrestrial all exhibit alternation
  of generations with a trend of increasing
  dominance of the sporophyte (as opposed to the
  gametophyte)

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II. Colonizing Land

• A. plants with complex bodies comprised of
  subterranean organs (to access water
  minerals) and aerial organs (to access light
  CO2)
• B. must prevent water loss (especially in
  embryo) developed a cuticle stomata in the
  leaf surface allow gas exchange gametes
  embryo protected by gametangia ( later seeds
  fruits)

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Colonizing Land (cont.)

• C. rigidity - provided by substance such as
  lignin which hardens cell wall of woody tissue
• D. protection from harsh environments -
  provided by sporopollenin in walls of spores
  pollen grain coats

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Colonizing Land (cont.)

• E. gametes must be dispersed in non- aquatic
  medium (led to development of pollen, and later
  flowers) (probably played a role in development
  of alternation of generations)
• F. water and minerals must be transported
  throughout the body of the plant (led to
  development of vascular tissue)

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III. Classification - 11 div.

• A. Division Bryophyta (mosses) - first to
  develop gametangia (antheridium archegonium)
  flagellated sperm no vascular tissue lack
  lignin fortified tissue gametophyte is
  dominant no true roots, stems, or leaves
• B. Division Hepatophyta (liverworts)
• C. Division Anthocerophyta (hornworts)
• most closely related to vascular plants

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11 divisions (cont.) seedless vascular plants

• D. Division Pterophyta (ferns) - true roots,
  stems, leaves vascular tissue (xylem
  phloem) lignified support tissue sporophyte is
  dominant no seeds flagellated sperm
• E. Division Lycophyta (club mosses ground
  pines)
• F. Division Sphenophyta (horsetails)