BRYOPHYTES – GENERAL CHARACTERISTICS 

Introduction

Bryophytes are non-vascular land plants, including mosses, liverworts and hornworts. They represent distinct living lineages rather than a step between algae and modern ferns. Their swimming sperm require water to reach the egg during sexual reproduction.

The study of bryophytes is called Bryology.

Bryophytes: Morphology, Reproduction and Classification | Botany Notes


1. Habitat and Distribution

  • Bryophytes are cosmopolitan, found on all continents including Antarctica
  • Mostly occur in moist, shady habitats

  • Grow on:
  • Soil (terrestrial)
  • Rocks (lithophytes)
  • Tree trunks and bark (epiphytes)
  • Walls and damp bricks
  • Some species are aquatic (e.g., Riccia fluitans)

2. Plant Body Organization

  • Plant body is thalloid or leafy
  • No true roots, stems, or leaves
  • Body differentiation:

  1. Thalloid bryophytes → liverworts (e.g., Marchantia)

  2. Leafy bryophytes → mosses (e.g., Funaria)

  • Attachment to substratum by rhizoids, not roots
Bryophytes: Morphology, Reproduction and Classification | Botany Notes


3. Vascular Tissue

  • Xylem and phloem are absent
  • Transport of water and food occurs by:

  1. Diffusion

  2. Capillary action

  • Some mosses possess primitive conducting cells:

    1. Hydroids (water conduction)

    2. Leptoids (food conduction)

    These are not true vascular tissues

4. Rhizoids

  • Rhizoids are unicellular or multicellular

  • Function:

  1. Anchorage

  2. Absorption of water and minerals

  • Lack root cap and vascular tissues
  • Liverworts → unicellular rhizoids
  • Mosses → multicellular rhizoids

5. Dominant Gametophyte Generation

  • Life cycle shows heteromorphic alternation of generations
  • Gametophyte (n) is:

  1. Green
  2. Photosynthetic
  3. Free-living
  4. Dominant phase

  • Sporophyte (2n) is:

  1. Small

  2. Attached to gametophyte
  3. Partially or fully dependent

6. Sporophyte Structure

In many mosses and liverworts, the sporophyte has:

  • Foot – absorbs nutrients from gametophyte
  • Seta – stalk that elevates capsule
  • Capsule – produces spores
  • Photosynthetic capacity varies: green moss and hornwort sporophytes can photosynthesise, while liverwort sporophytes are more strongly dependent on the gametophyte
  • No independent existence

7. Reproductive Structures

Asexual Reproduction

Occurs by:

  • Fragmentation
  • Gemmae (e.g., Marchantia)
  • Buds and tubers

Sexual Reproduction

  • Oogamous
  • Male organ → Antheridium
  • Female organ → Archegonium
  • Both are multicellular and jacketed
  • Fertilization requires free water

8. Water Dependency (Amphibian Nature)

  • Male gametes are flagellated

  • Water is essential for:

  1. Movement of sperm

  2. Fertilization

  • Hence called amphibians of plant kingdom

9. Embryo Formation

  • After fertilization:

  1. Zygote remains inside archegonium

  2. Develops into a multicellular embryo

  • Presence of embryo distinguishes bryophytes from algae
  • This feature places bryophytes in Embryophyta

10. Spore Formation

Spore mother cells undergo meiosis in the capsule, producing haploid spores. These germinate to form:

11. Cuticle and Stomata

  • Cuticle is poorly developed
  • Stomata:
  • Absent in gametophyte
  • Present on sporophyte capsule (in mosses & hornworts)
  • Indicates transition towards land adaptation

12. Lack of Secondary Growth

  • No cambium
  • No secondary thickening
  • Limited size and height

13. Economic and Ecological Importance (Brief)

  • Soil formation
  • Pioneer species on bare rocks
  • Water retention (e.g., Sphagnum)

  • Used in:

  1. Horticulture

  2. Peat formation

  3. Packing material

  4. Environmental indicators

14. Classification (Brief Overview)

The broad bryophyte group includes three lineages: liverworts (Marchantiophyta), hornworts (Anthocerotophyta) and mosses (Bryophyta). The following names are often used in traditional course classifications; their ranks and scope should be checked against the classification required by your syllabus:

  1. Hepaticopsida (Liverworts)
  2. Anthocerotopsida (Hornworts)
  3. Bryopsida (Mosses)

Frequently asked questions

Do bryophytes have true roots?

No. Rhizoids anchor the plant, while water can also be absorbed across the gametophyte surface.

Are bryophyte spores haploid or diploid?

They are haploid. Meiosis occurs in the diploid sporophyte before spores develop into gametophytes.

Which bryophyte generation has stomata?

Where present in mosses and hornworts, stomata belong to the sporophyte. Liverworts lack true stomata.

Reference: OpenStax Biology 2e: Bryophytes.