Question

Bryophyta (mosses) - From which group did plants evolve from? - Main characteristics of Bryophytes - Which life stage is dominant: gametophyte or sporophyte?

- Groups of Bryophytes and main characteristics of each

- Relevance of Bryophytes

Answer 1

Bryophytes have evolved from green algae as they posses characters similar to them such as chlorophyll a and b.They also produce starch and there is a need of water for their reproduction.

Main Characteristics of bryophytes:

1) They are like amphibians i.e although majority of them are terrestrial,they require lots of moisture and humidity in their surrounding.

2) Plant organisation is of two types : thalloid and leafy.

3) They get their nutrients from dust, rain water and substance dissolved in water at the soil's surface.

4) The gametophytes dominate the life cycle.

5) The sporophyte is short lived,and unbranched and produces a terminal sporangium.Although photosynthetic the sporophytic is permanently attatched to and partially dependent on gametophyte.The sporophyte of bryophytes do not have a direct connection to the ground.

6) The copulatory organs are jacketed and multicellular.

7) Fertilisation take place in water.

The gametophyte is the dominant life stage.

Bryophytes are categorised into three classes :

1. Liverworts :

1) Gametophytic plant body

2) absence of pyrenoids

3) presence of many chloroplasts in photosynthetic cells.

4) May be dioecious or monoecious

5)absence of columella in capsule

6) Capsule is without stomata

2.Mosses

1) Gametophytic plant body.

2) Protenema contains gametophores

3) Leaves are above the brances

4) Mid ribs are present in leaves.

5) Sporophyte is differentiated into foot, capsule and seta.

6) Absence of elaters.

3.Horn worts:

1) Non vascular

2) Gametophytic plant body.

3) absence of air chambers.

4) Chloroplast contain pyrenoid and present in cell

5) stomata is present in epidermis

Bryophytes are important as they have high water retaining capacity and are the pioneer secies.They are the first land plants.Sphagnum helps in the formation of peat.They are used in medicines as well as used in bedings due to their high water holding capacity.