Liverworts are usually found in moist habitats such as river banks, marshes, wet tree barks, damp soil etc.
Liverworts have a thalloid structure. The thallus is flat and dorso-ventral. The upper side consists of leaf like structures and the lower side bears numerous rhizoids.
- Takes place by fragmentation of the thallus, or by the formation of specialized structures called gemmae.
- Gemmae are asexual buds are borne on small receptacles called gemma cups found on the thalli.
- These buds detach from the parent and germinate into new individuals.
- Gametophyte is the dominant generation.
- Thallus bears male and female sex organs – antheridium and archegonium.
- It produces the gametes which fuse to form a zygote.
- Zygote develops into a sporophyte.
- Sporophyte is short lived.
- It is differentiated into a foot, setae and capsule.
- Capsule bears spores which germinate into gametophyte.
Mosses are found in wet and damp habitats. They are widely present in urban environments such as walls, driveways, and other man – made structures.
e.g.- Funaria, Polytrichum, Sphagnum.
Mosses have two phases in the life cycle. The gametophyte plant has leaf like and stem like structures. The gametophyte consists of a raised stalk called seta, which terminates in a sporangium.
Gametophyte: The gametophyte is the predominant generation. It consists of two phases – Protonema stage and the Leafy stage.
Protonema: The spore first germinates to the protonema stage. It is highly filamentous and branched. It is a green creeping form. Vegetative reproduction (by fragmentation or budding) takes place during this stage.
Leafy stage: It is the second stage. It develops from a lateral bud which arises on the protonema. The body is composed of a slender axis bearing spirally arranged leaves and numerous rhizoids. This stage bears the sex organs (antheridia and archegonia) at the apex of the leafy shoots. It produces the gametes.
Sporophyte: Gametes fuse to form the zygote which develops into a sporophyte. It is composed of a foot, setae and a capsule. The capsule contains spores, which germinates into the gametophyte.