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Chapter 20: Nonvascular Plants: Mosses, Liverworts, and Hornworts…

- - - - Gametophores: Leafy Stems
        
        form dense mounds
        
        Grow closely together
        
        apical meristem/prominent apical cell
        
        derivative cells subdivide: tissues
        
        Leaves
        
        Midrib & Three rows
        
        one cell thick except @ midrib
      - Not homologous with vascular plants
      - Moss Stems
        
        slender&little tissue dif
        
        surface layer not epidermis
        
        stem tissues: cortex
    - - hyroids: cells that conduct water&dissolved minerals.
      - Leptoid: cells like sieve cells
        
        elongated
        
        interconnect w/ adjacent cells
        
        Lack nuclei
    - - begins w germination
      - sends out long chlorphyllous cell
      - mitosis->protonema: network of these cells
      - cytoplasmic cells form on protonema
      - grow upright to make gametophore
    - - gametophore makes gametangia
        
        sperm produced in antheridia
        
        short stalk
        
        outermost layer of sterile cells
        
        Archegonia make eggs
        
        shaped like vase
        
        neck of vase is hollow at maturity
        
        single egg at base of neck
      - all mosses oogamous #
  - - - outer and inner layer of sterile cells
- - - - resembles moss: thin leaves&slim stems
      - two rounded lobes w/ no midrib
    - - Show less resemblance to moss
      - Flat Ribbon-like or heart shaped w/ bilateral symmetry
      - Thallus: Body
        
        no roots, stems, or leaves
        
        Stratified and tend to be thicker
        
        side by substrate bears unicellular rhizoids
- - - - alters broken down cells chemically
    - - special mucialge chamber forms
        
        cells lining chamber become antheridia
        
        chamber expands as antheridia grow
        
        as sperm mature, sterile outer cells change chloroplast to chromoplasts
    - - egg lies below short neck and neck canal
        
        surrounded by thallus cells
  - - - just above foot is a meristem that makes sporang. tissues
    - - replaced by more cells from basal meristem
      - makes sporangium long and horn-like
      - at the tip sporangium is open and mature