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Bryophytes: Mosses and Liverworts

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Usually live in moist, cool environments ... Grow in dense carpets or tufts. See page 595 for examples of mosses. Liverworts. Small ... – PowerPoint PPT presentation

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Title: Bryophytes: Mosses and Liverworts


1
BryophytesMosses and Liverworts
2
General Characteristics
  • Spore- producing plants that have no vascular
    tissue
  • Usually live in moist, cool environments
  • Must carry on all life functions where there is
    steady supply of moisture
  • Cant compete with neighboring vascular plants

3
Mosses
  • Small
  • Leafy stems
  • Grow in dense carpets or tufts
  • See page 595 for examples of mosses

4
Liverworts
  • Small
  • Grow in clumps
  • Occur in many environments, from water to desert
  • Have oily or shiny surface
  • Two groups
  • Thallose thallus broad ribbonlike body, looks
    like lobed leaf
  • Leafy creeping, 3 rows of flat, thin leaves
    attached to stem

5
Reproduction
  • Alternation of generations between diploid
    sporophyte and haploid gametophyte (like all
    plants)
  • Only plant division where gametophyte generation
    is dominant

6
Structure of Mosses
  • Protonema small, green filament of cells that
    develops into either male or female gametophyte
  • Antheridium reproductive structure in which
    sperm are produced
  • Archegonium reproductive structure in which eggs
    are produced

7
Life Cycle of a Moss(Diagram on p. 597)
  • 1. Sporophyte generation develops from
    gametophyte
  • 2. Spores are produced by meiosis in capsule of
    sporophyte
  • 3. Spore capsule ripens, bursts, releases
    spores. Spore germinates to form a protonema
  • 4. Atheridium develops on male gametophyte
  • 5. Archegonium develops on female gametophyte
  • 6. Sperm are released and swim to archegonium
  • 7. Fertilization takes place inside archegonium
  • 8. Zygote divides by mitosis to form new
    sporophyte

8
Asexual Reproduction in Bryophytes
  • Vegetative reproduction plant gives rise to new
    individuals without going through the alternation
    of generations
  • Mosses can break into pieces when it is dry and
    brittle
  • With the arrival of wetter conditions, each piece
    then becomes a whole plant
  • Gemmae tiny, haploid boides that grow in cups on
    surface of gametophyte
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