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

- - - - have neither
        
        vascular tissue
        
        seeds
    - - have vascular tissue
        
        but not seeds
    - - have both
        
        vascular tissue
        
        seeds
  - - - low surface-to-volume ratio
      - better at retaining water
    - - coordinate gamete reproduction
        
        with periods of moisture
        
        sperms need to swim
    - - nonvascular plants
        
        use turgid parenchyma cells
        
        cannot grow very tall
      - vascular plants
        
        xylem evolved
        
        good at conducting water
        
        Phloem then evolved
        
        shaded basal part
        
        could be nourished
        
        allowed plants to grow taller
        
        made evolution feasible for
        
        roots
        
        meristems
        
        organ primordia
        
        allows for mobilization of
        
        sugars
        
        minerals
        
        hormones
- - - - have vascular tissue
    - - reproductive cells are always surrounded
        
        by one or several
        
        layers of sterile cells
    - - filaments but rather
        
        true parenchyma derived by
        
        three-dimensional growth
        
        usually from apical meristems
    - - have leafy stems
    - - have cuticle over
        
        much of their bodies
  - - - alternation of heteromorphic generations
        
        sporophyte and gametophyte
        
        differ from each other structurally
        
        gametophyte
        
        larger, more prominent generation
        
        collects minerals
        
        can spread rapidly
        
        via asexual reproduction
        
        sporophyte
        
        much smaller
        
        more temporary
        
        often very inconspicuous
        
        never independent of gametophyte
        
        stay attached
        
        absorb minerals from them
        
        never branch
        
        never have leaves
- - - - derivative cells subdivide
        
        producing tissues of
        
        stems
        
        stem tissues
        
        all called cortex
        
        outer cells may be
        
        1 more item...
        
        OR
        
        2 more items...
        
        may be uniform in
        
        1 more item...
        
        little tissue differentiation
        
        always slender
        
        leaves
        
        no stoma occurs
        
        would be useless
        
        because leaves are unistratose
        
        underside
        
        little protection against
        
        desiccation
        
        capable of absorbing water
        
        directly from
        
        3 more items...
        
        uncutinized
        
        cuticle occurs only
        
        on upper surface
        
        of most moss leaves
        
        thickness
        
        most are one cell thick
        
        except at
        
        2 more items...
        
        most have midrib (costa)
        
        aligned in three rows
        
        at least as young
      - gametophores grow from
        
        an apical meristem
        
        contains a prominent apical cell
      - have leaves but
        
        not homologous to
        
        vascular plants
      - gametophores
        
        some plants
        
        grow loose and open
        
        particularly in cool wet areas
        
        leafy stems
        
        many grow close together
        
        form dense mounds
        
        tightly appressed
    - - some mosses
        
        primarily the family Polytrichaceae
        
        innermost cortex composed of cells
        
        called hydroids
        
        conduct
        
        water
        
        dissolved minerals
        
        elongated cells that
        
        lose cytoplasm when mature
        
        species with hydroids
        
        typically have leptoids
        
        4 more items...
      - majority of mosses
        
        lack hydroids and leptoids
        
        water is conducted along
        
        exterior of their stems
        
        by capillary action
        
        leaves and stems
        
        are so small they
        
        form spaces narrow enough to
        
        act as capillary channels
        
        and transport water
    - - growth of the gametophore
        
        begins when a spore germinates
        
        sends out long, slender
        
        chlorophyllous cell
        
        undergoes mitosis
        
        produces a branched system
        
        1 more item...
    - - gametophore produce
        
        gametangia
      - all mosses are
        
        oogamous
        
        every species has
        
        small biflagellate sperm cells
        
        large non motile egg cells
      - sperms produce in microgametangia
        
        called antheridia
        
        consist of
        
        short stalk
        
        outermost layer of sterile cells
        
        inner mass of cells that
        
        differentiate into sperm cells
      - eggs occur in megagametangia
        
        called archegonia
        
        shaped like
        
        vase with long neck
        
        neck is hollow at maturity
        
        single egg located at base
  - - - transverse division
        
        and basal cell
        
        develops into
        
        small, bulbous tissue
        
        called foot
        
        interface with the gametophore
        
        1 more item...
        
        cells are
        
        1 more item...
        
        upper cells grow
        
        1 more item...
    - - but relatively complex structurally
        
        has a
        
        true epidermis
        
        with a stomata
        
        at least on base
        
        of sporangium
        
        1 more item...
- - - - two groups
        
        leafy liverworts
        
        gametophyte greatly resembles
        
        that of moss
        
        thin leaves on
        
        a slender stem
        
        however
        
        they typically have
        
        1 more item...
        
        leaves arranged in
        
        three clearly defined rows
        
        two rows bigger
        
        with one small
        
        gametophore stem
        
        grows by apical cell
        
        with
        
        3,4,or 5 sides
        
        2 more items...
        
        tissue is simple parenchyma
        
        no thickened walls
        
        no conducting cells
        
        thallose liverworts
        
        gametophyte phase initiated by
        
        spores geminate and
        
        establish small, temporary protonematal phase
        
        never as extensive
        
        1 more item...
        
        only a few cells
        
        1 more item...
        
        show less resemblance to mosses
        
        not leafy at all but
        
        flat and
        
        ribbon like or
        
        heart shaped and
        
        1 more item...
        
        body
        
        referred to as a thallus
        
        a body without
        
        roots
        
        stems
        
        leaves
        
        stratified
        
        tend to be thicker
        
        than those of
        
        leafy liverworts
        
        mosses
        
        side next to substrate
        
        bears unicellular rhizoids
        
        many cells contain large oil drops
        
        SIde away from substrate
        
        cells
        
        have no oil but
        
        rich in chlorophyll
        
        sexuality
        
        bisexual
        
        producing
        
        antheridia and archegonia
        
        unisexual
        
        male gametophytes
        
        produce antheridiophore
        
        umbrella-shaped outgrowth
  - - - foot
      - seta
        
        extremely delicate
        
        composed of
        
        clear, thin-walled cells
        
        collapse quickly
      - calyptra-covered
    - - is globulose
      - while young
        
        is bright green
        
        is chlorophyllous
      - lacks a columella
        
        the central mass of sterile cells
- - - - three or four
        
        protonema cells are produced
        
        before the gametophore phase
        
        is established in most species
    - - always thin
        
        at least along edges
      - shaped like ribbon
        
        or a heart
        
        or may grow outward irregularly
      - typically live less than a year
        
        in temperate climates
      - act as winter annuals
        
        appear in
        
        cool, moist autumns
      - internally
        
        have numerous chambers
        
        young plants
        
        have mucilage chambers
        
        formed by
        
        as cells break down
        
        altered chemically
    - - parenchymatous
      - succulent but brittle
      - does not tolerate drying
  - - - hard to find
    - - gametophore tissue
        
        but no seta
        
        or discrete sporangium
      - just above foot
        
        is a meristem
        
        that continously
        
        produces new sporangium tissue
    - - long, horn-like cylinder
      - at tip
        
        is mature and open
        
        as result of
        
        dehiscence along two linear apertures
      - outer layer of sterile cells
        
        is thick and chlorophyllous
    - - have a columella