Plant Diversity: How Plants Colonized Land

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Plant DiversityHow Plants Colonized Land

• The Origins of Plants
• Bryophytes
• The Origin of Vascular Plants
• Seedless Vascular Plants

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Overview

• Common characteristics chloroplasts with
  pigments cell walls of cellulose plastids
• Development of embryophytes
• Alternation of generations
• Nonvascular and vascular forms

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Alternation of Generations
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The Origin of Plants

• Common ancestor with green algae based on
  similarities of cell walls and chloroplasts
• Alternation of generations may have evolved from
  a delayed meiosis
• Shallow water existence preadapted plants for a
  terrestrial lifestyle (waxy cuticle, protected
  gametes, protected embryo)

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Plant Phylogeny
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Bryophytes

• Mosses, liverworts, and hornworts
• Key evolutionary development protected gametes
• Dominant gametophyte
• Sporophyte dependent
• amphibians of the plant kingdom?
• Spores are dispersal mechanisms

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The Origin of Vascular Plants

• Dominant sporophyte
• Regional specialization of the plant body (roots,
  leaves, etc.)
• Structural support
• Vascular system (xylem and phloem)
• Seeds (in some)
• Pollen (in some)
• Two major lines seeds and seedless

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Seedless Vascular Plants

• Ferns, horsetails, and lycophytes
• Still require water for fertilization
• Dominant sporophyte
• Independent, but reduced gametophyte
• Spores are dispersal mechanisms
• Formed coal forests during Carboniferous period

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Life Cycle of a Fern