Bryophytes: Terrestrial Plants with Simple Morphology
Bryophytes
Bryophytes are characteristic of moist terrestrial environments. Some show adaptations allowing them to occupy diverse environments, from aquatic to polar regions. They depend on water for anterozóide displacement to the egg cell. No marine representatives exist in this division.
These plants are used ornamentally, with fern roots as orchid substrate. Samambaiuçu trunks are used. Some ferns have anthelmintic properties, while certain shoots are carcinogenic.
Bryophytes
This division comprises terrestrial plants with simple morphology, known as mosses or liverworts. They are eukaryotic, multicellular organisms, with unicellular reproductive organs, classified under Plantae.
NOTE: bryon (Greek) – moss, phyton (Greek) – plant.
- They have chlorophyll a and b.
- They store starch as a polysaccharide.
- Cells have cellulose walls.
- They have a cuticle.
- Lifecycle is diplobionte heteromorphic, with a sporophyte dependent on the gametophyte.
- Organic reproduction occurs.
- The esporófito is unbranched, with a single terminal sporangium.
- Gametângio and sporangia are surrounded by sterile cells.
Bryophytes are diplobionte, showing heteromorphic alternation of generations between a branched, photosynthetic gametophyte and a dependent, unbranched sporophyte.
Spores from meiosis in the sporophyte germinate to form gametophytes. Spores can directly produce the plant or a filamentous phase (protonema) leading to the upright part.
Gametophytes have rhizoids, filídios, and caulídios. Simple forms are prostrate (stalks), while differentiated forms are erect (leafy).
Reproductive structures, archegonia (female) and anterídios (male), develop at the spore stage.
The zygote germinates on the mother plant, with the sporophyte remaining attached.
Sporophytes have a foot, seta, and capsule. The foot absorbs substances. The capsule contains spores. A calyptra may cover the capsule.
Bryophyte Reproduction
1. Gametes: Anterozóide fertilizes the egg cell in humid conditions.
2. Spore: Spores are released via peristome movements.
3. Material – 4 ways:
- Fragmentation: Development from fragments.
- Gems (runners): Specialized structures forming new individuals.
- Apomixis: Sporophyte development without meiosis.
- Apogamia: Gametophyte development without fertilization.
Historically, “muscus” included bryophytes, lichens, algae, and some invertebrates.
Dillenius (1741) first studied these organisms comprehensively. Linnaeus (1753) classified bryophytes near flowering plants.
Hedwig (1801) correctly interpreted the structures and life cycle.
Bryophytes are divided into three classes:
Hepaticae (Liverworts)
About 300 genera and 10,000 species.
Anthocerotae
About 300 genera and species.
Musci (Mosses)
About 700 genera and 14,000 species.