Marchantia Thalli: These have Apical Cells & Branch Dichotomously at the Apex. They are Dorsiventral in that they have distinct upper (Dorsal) and lower. Moreover, in Marchantia asexual reproduction occurs by means of fragmentation of the thallus or via gemmae produced from cells of gemma. Marchantia belongs to the complex thalloid group. The Marchantia thallus (plant body) is a flattened strap-like structure, µm thick, divided into three.
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Asexual reproduction occurs by means of gemmaediscoid clumps of cells which are genetically identical to the parent and contained in cup-like structures on marchantia thallus upper surface of the plant.
Quick Notes on Marchantia (With Diagrams) | Biology
These are dispersed marchantia thallus rain splashes into the marchantia thallus and develop into new plants. This modular construction protects the whole organism from local trauma. Each compartment has some level of autonomy.
Each compartment has one large Marchantia thallus. Section through a Marchantia Thallus: The elater mother cells elongate considerably to form long, slender diploid cells called elaters.
Elaters are pointed at both the ends and have two spiral bands or thickenings on the surface of the wall.
These are hygroscopic in nature and help in dispersal of spores Fig. The spore mother cell is diploid and divides meiotically to form four haploid spores which remain arranged tetrahedrally for quite marchantia thallus time Fig.
The spores later become free and remain enclosed by marchantia thallus capsule wall along elaters. The quadrant type of development of sporogonium is quite common in many species of Marchantia e. In it the hypo basal cell forms the foot, marchantia thallus middle seta and the epibasal cell develops into capsule.
However, it is the rare type of embryo development in M.
A mature sporogonium can be differentiated into three parts, viz. It is bulbous and multicellular.
It is composed of parenchymatous cells. Marchantia thallus acts as anchoring and absorbing organ. It absorbs the food from the adjoining gametophytic cells for the developing sporophyte.
It connects the foot and the capsule. Marchantia thallus maturity, due to many transverse divisions it elongates and pushes the capsule through three protective layers viz.
It is oval in shape and has a single layered wall which encloses spores and elaters. It has been estimated that as many as 3, 00, spores may be produced in single sporogonium and there are spores in relation to one elater.
As the sporogonium matures, seta elongates rapidly and pushes the marchantia thallus in the air through the protective layers Fig.
Marchantia - Wikipedia
The ripe capsule wall dehisces from apex to middle by four to six irregular teeth or valves. Marchantia thallus annular thickening in the cells of the capsule wall causes the valves to roll backward exposing marchantia thallus spores and elaters.
The elaters are hygroscopic in nature. In dry weather they lose water and become twisted. When the atmosphere is wet, they become untwisted and cause the jerking action.
Due to this the spore mass loosens and spores are carried out by marchantia thallus currents Fig.