Mosses (Phylum Bryophyta) Liverworts (Phylum Hepatophyta)




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Bryophytes

Chapter 16

Bryophytes

  • Mosses (Phylum Bryophyta)

  • Liverworts (Phylum Hepatophyta)

  • Hornworts (Phylum Anthocerophyta)

Bryophytes

  • Transitional between green algae and plants in their characteristics

  • Bryophytes and vascular plants have:

Thalloid

  • Hornworts and liverworts have flat and dichotomously branched gametophytes called thalli

  • Thalli are undifferentiated

  • In comparison, gametophytes of leafy bryophytes and mosses have “stems” and “leaves”

Rhizoids

  • Gametophytes are attached to surfaces by rhizoids

  • Rhizoids serve to anchor the plant in bryophytes

Reproduction

  • Asexual reproduction is achieved through formation of gemmae

Sexual reproduction

  • Male gametangia = antheridia

  • Female gametangia = archegonia

  • Bryophytes have flagellated sperm that must swim to the egg

  • Reproduction therefore requires water

Spores

Hepatophyta

  • Liverworts or hepatics

  • Some genera develop protonema, but most gametophytes develop directly from spores

  • Gametophytes continue to grow from apical meristem

Three groups of liverworts

Complex thalloid liverworts

  • Cells are differentiated

  • Marchantia is an example

Anthocerophyta

  • Small phylum of 100 species

  • Cells of most species have a single large chloroplast

  • Rosette-like gametophyte

  • Dichotomous branching is not apparent

Bryophyta

  • Three classes

  • Sphagnidae – Peat mosses

  • Andreaeidae – Granite mosses

  • Bryidae – True mosses

Sphagnidae

  • Unusual protonema

  • Acidify their environment

  • Perforated cell walls allow high waterholding capacity

Andreaeidae

Bryidae

Water conducting tissue

  • True mosses have a central strand of water conducting tissue called hadrom

  • Hydroids are water conducting cells

  • In some mosses, food conducting cells called leptoids are present (leptom)

Cushiony versus feathery



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