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Chapter 21 (Microphyll Evolution (LYCOPHYTES (genera Drepanophycus and…

- - - - advancement of true roots
        
        sporangia cluster in Strobili
        
        homosporous and heterosporous
        
        micro/megagametophytes
        
        fossils indicate convergent evoultion with seed plants
      - extinct Lepidodendron, Sigillaria, Stigmaria
        
        vascular cambium and 2ndany growth
  - - - Trimerophyton, Psilophyton, Pertica
      - distinct advancement of Rgyniophytes #
      - unequal branching, 1 stem (OVERTOPPING)
        
        Pertica displays pseudomonopodial branching
        
        1 main trunk
        
        branching became regualr/controlled
        
        Upper Devonian Period evolved into the ferns and seed plant
        
        origin of megaphylls (euphylls)
        
        3 types homoplasic leaves in plants
        
        3 more items...
- - - - in center and metaxylem
      - differentiates on outer edge of xylem mass
    - - metaxylem in center of xylem mass
      - protoxylem on edge as several groups next to phloem
    - - evolved later
      - pith os present in center,
      - stems of ferns and seed plants
  - - - opened transversely/top edge
      - xylem exarch protostele
      - sporangia were lateral not terminal
      - Zosterophyllum
        
        small bunches w/ cuticle
        
        ordinary epidermal cells
        
        stomata on upper portion/naked stem
        
        genera show morphological changes
- - - - Rhynia and Aglaophyton other types similar to to Cooksonia
        
        Horneophyton
        
        sporophytes w/ naked axes
        
        dichotomously
        
        stomata and terminal sporangia
        
        similarities between of posibilities that vascular plants came from hornwort-like ancestors # # #
- - - - jointed structure
      - whorl fused leaves at nodes
      - has pith (siphonosteles)
      - Reproductive Structures
        
        Equisetum, specialized sporangia
        
        groups of 5-10 (umbrella-shaped sporangiospore
        
        ancient clade few surviving species
- - - - node leaf trace diverges from siphonostele
        
        small vascular cylinder (parenchyma) (leaf gap)
        
        apical grows inward - young leaf (fiddlehead)
        
        underside leaf has sori
        
        2 types of sporngia
        
        leptosporangium
        
        eusporangium
        
        spore germinates- -heart shape photosynthetic gametophyte w/ rhizoids