Bryophytes are amphibians of the plant kingdom. They occur in damp, shady places.
- Have a haplodiplontic life cycle.
- Plant body is the gametophyte.
- Sporophyte is parasitic on the gametophyte.
- Plant body is a thallus i.e., not differentiated into root, stem & leaf.
- Vegetative reproduction is by fragmentation, gemmae & tubers.
- Highly specialized oogamous, sexual reproduction.
- Male sex organ is antheridium which produces biflagellate antherozoids.
- Archegonium (flask-shaped) is the female sex organ, which produces an egg.
- Fertilization occurs with the help of water and movement of antherozoids towards the archegonia is chemotactic.
- The zygote divides immediately to form the sporophyte that grows on the gametophyte.
- Sporophyte is differentiated into foot, seta & capsule.
- Capsule produces haploid spores.
- Spores on dispersal germinate to form the new gametophytic plant.
Divided into 3 classes:
- Hepaticopsida (liverworts): e.g., Riccia, Marchantia, Porella.
- Anthoceropsida: e.g., Anthoceros.
- Bryopsida (mosses): e.g., Funaria, Sphagnum, Polytrichum.
- Dorsoventrally flattened thallus.
- Unicellular rhizoids & multicellular scales present.
- They are dioecious.
- Sex organs develop in groups on long stalks i.e., antheridiophore & archegoniophore.
- Haploid spores & diploid elaters are produced in the capsule.
- Elaters are hygroscopic & help in dispersal of spores.
- They have a protonema stage and an erect stage.
- Spores germinate to produce filamentous, branched protonema, that produces buds.
- Buds form the erect stage.
- The erect stage has a stem like axis, leaf-like phylloid & multicellular rhizoids.
- They are monoecious & autoecious.
- Antheridia & archegonia develop in groups along with paraphyses on the upper part of the stem, surrounded by leaves.
- Sporophyte is semi-parasitic on gametophyte.
- Capsule is an elaborate structure divided into lower apophysis, middle theca & upper operculum.
- Apophysis is photosynthetic.
- Spore sac present in theca, produces haploid spores.
- Covering spore sac is the operculum & peristome teeth.
- Peristome teeth are hygroscopic, present in 2 rows of 16 each. They help in dispersal of spores.
- Help in soil formation & prevent soil erosion.
- Used as fodder for cattle.
- Peat used as fuel is obtained from Sphagnum.
- Due to their water retaining capacity, Sphagnum is used in preserving & transporting living materials
Read also Alternation of Generations