To study the morphology of thallus, w.m. rhizoids and scales, v.s. thallus through gemma cup, w.m. gemmae from temporary slides, v.s. antheridiophore, archegoniophore, and sporophyte from the permanent slides of Marchantia.

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CLASSIFICATION

Division : Bryophyta
Class     : Hepaticopsida
Order     : Marchantiales
Family   : Marchantiaceae
Genus   : Marchantia


MORPHOLOGICAL FEATURES OF THE THALLUS-


1. The main plant body is gametophytic thallus. Gametophyte is small, well developed and autotrophic.

2. The plant body is dorsiventral, the dorsal surfaces is dark green having a distinct midrib and dichotomously branched.

3. The ventral or the lower surface bear numerous rhizoids and scales.

4. The rhizoids are unicellular and branched structures meant for anchorage and absorption. They may be smooth walled or tuberculated (bearing peg-like projections).

5. The scales are purplish multicellular structures which protect the thallus from the dessication by secreting the mucilage.

6. The dorsal surface also bears small gemma cups on the mid ribs. Inside the gemma cups many erect stalked gemmae are present which helps in vegetative reproduction of Marchantia.

7. Sexual reproduction is oogamous. The male reproductive structure is antheridia and the female structure is archegonia.

8. The antheridia bearing gametophore is called antheridiophore. The antheridiophore consists of a narrow stalk and disc shaped male receptacle. The receptacle consists of upper epidermis photosynthetic region and antheridial chambers bearing antheridia.

9. The archegonia bearing gametophore is called archegoniophore. It also consist of stalk and receptacle. The receptacle is eight lobed structure. It is differentiated into an upper photosynthetic and lower storage region. The archegonia occur on the ventral surface of the receptacles. All the archegonia of a lobe is covered by a membrane called perichaetium.

10. After the fertilization the zygote is formed which develops into the sporogonium. The sporogonium is differentiated into foot, seta and capsule. Foot is the basal portion of the sporogonium. It helps in absorption and fixation of the sporophyte with thallus. The seta connects the foot with the capsule.The capsule is spore bearing structure of the sporogonium which bears the haploid spore.




Viva-Voce


Q.1. What is thallus?

Ans. the plant body which is not differentiated into root, stem and leaves. 

Q.2. What type of thallus is found in Marchantia?


Ans. Gametophytic

Q.3. Gemma cups assist in?


Ans. Vegetative reproduction.


Q.4. Name the three parts of sporogonium in Marchantia?


Ans. Foot, seta and capsule.

Q.5. The female reproductive structures in Marchantia are known as?


Ans. Archegonia


Q.6. Name the fertile portion of sporogonium?

Ans. Capsule


Q.7. Name two types ofrhizoids in Marchantia?

Ans. Smooth walled and tuberculated

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