What is Marchantia?
Gametophyte
- It is terrestrial and grows in damp shady 1. I and moist places.
- The plant body is green, prostrate, dichoto mously branched thallus.
- Thallus lobes bear distinct midrib, which 3. T ends in a terminal notch.
- Upper surface of thallus is marked by 4. U rhomboidal areas (areoles), each with a rh distinct central pore.
- No algae are present in the thallus.
- Presence of gemma cups is another distin 6. N guishing features.
- Both rhizoids and scales arise from the ventral surface of thallus, along the midrib region.
- Rhizoids are unicellular, aseptate and 8. R unbranched. These are of two types: smooth walled and tuberculated.
Anatomy
- Internally the thallus is several layers thick.
10. Cells are differentiated and arranged in two distinct regions, the upper green photosynthetic regions and lower storage parenchym region.
11, Growth takes place by means of a group of 11. Growth ta apical initials, lying deeply in the notches of each lobe.
Sex Organs
- All species are dioecious strictly,
- Sex organs are borne on special upright 13. Sex organ terminal branches of thallus called gametophores.
- Sex organs are developed in a line back from the apex in acropetal order.
- Sex organs are exogenous in origin.
- Antheridium is an ovoid body supported on a multicellular and short stalk.
- Archegonia are flask shaped possessing?
(1) A short but distinct stalk.
(ii) Long neck with greater number of neck camal cell.
(iii) Hang downward from the under surface of receptacle.
Sporophyte:
1. Capsule is not much elaborated.
- It is differentiated into a foot short seta and capsule.
3. The short seta elongates rapidly but slightly just to push the capsule beyond adds the protective sheaths.
5.Capsule wall is?
(1) Single layered in thickness and at maturity develop ring like thickenings. No photosynthetic tissue or air space is present.
(ii) Capsule wall is derived from the entire amphithecium.
7. Archespor endothecium.
- Sporogenous tissue fills the entire space 8. Sporogeno within the capsule wall.
- Major portion of sporogenous tissue is 9. Sporogen differentiated into the spore mother cells mother ce only a few remain sterile and function as cells. Lac nurse cells or elastors.
- The columella is absent.
- Dehiscence: Capsule wall splits open into 4-6 irregular structures from apex to the middle, exposing a mass of spores and elaters.
- Elaters bear spiral thickening and are 12. Pseudoel hygroscopic in nature and hence help in spore dispersal.
- The sporophyte is totally parasitic for its 13. Sporoph nutrition on the parent gametophyte gametop plant.
- Sporophyte is a short lived structure. The 14. Sporoph whole sporophyte tissue perishes by the structure time the spores reach maturity.