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Chapter 22: Seed Plants I: Seed Plants Without Flowers ("…

- - - - heterosporous
  - - - Chauleria
      - from Middle Devonian Period
    - - hole in integument
      - permitted sperm cells to swim to the egg
      - similar to angiosperm ovules
      - some fossils help us understand the early stages
    - - holding area for microspores
        
        evolved into pollen grains
    - - evolved into ovules with integuments
- - - - monopodial trees
        
        one main trunk
        
        many branches
  - - - simple
    - - compound
- - - - looks much like a large dicot tree
      - wood like conifers
        
        lacks vessels and axial parenchyma
      - reproduction is dioecious
        
        cones are not produced
      - ovules
        
        occur in pairs
        
        at ends of short stalk
        
        completely unprotected at maturity
      - popular ornamental
- - - - about 40 species
      - touch shrubs and brushes
    - - only species in the genus
      - exists only in deserts of South Africa or in cultivation
      - short, wide stem
      - only two leaves
    - - 30 species
      - mostly vines or small shrubs
      - leaves similar to those of dicots
- - - - foliage leaves bore seeds
- - - - was cup shaped
      - contained numerous sporangia