Note on Marchantia

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Marchantia

Marchantia

source:commons.wikimedia.org

fig: Marchantia

Classification

Kingdom: Plantae

Division: Bryophyta

Class: Hepaticae

Order: Marchantiales

Family: Marchantiaceae

Genus: Marchantia

Common name: Liverwort

Identifying character

  • It is kept in kingdom Plantae because it has the autotrophic mode of nutrition and cellulosic cell wall.
  • It is kept in division bryophyte because it is the amphibian plant which needs water for fertilization.
  • Genus name is Marchantia because gametophytic thallus is prostrate, dorsoventrally flattened and dichotomously branched.

Gametophyte: External morphology

Genus Marchantia represents about 65 species. It is commonly grown in moist, shady, damp and cool places. Gametophytic plant body of Marchantia is leafy, green and thallus. Type of thallus is prostrate, dorsoventrally flattened and dichotomously branched. Dorsal surface of the thallus is dark green in color. Each lobe of the thallus contains distinct midrib. Along the midrib, a small cup-like structure is present, called gemma cup which helps in vegetative reproduction. Apical part of the thallus contains small groove called apical notch which helps in further growth and development of thallus.

Ventral surface of the thallus is light green in color. It bears rhizoids and scales. Rhizoids are unicellular, unbranched and colorless. It helps in fixation and absorption of water and minerals. Rhizoids are two types i.e. smooth and tuberculate. In smooth rhizoids, the inner membrane is plane while tuberculate rhizoids are modified to form a tube-like structure. The scale is multicellular and violet in color due to the presence of anthocyanin pigment in their cytoplasm. It helps in protection and to keep the plant body moist. Scales are of two types: ligulate and appendiculate. A smaller undifferentiated scale called ligulate and larger differentiated scale called appendiculate.

Reproduction in Marchantia

In Marchantia, reproduction takes place by two methods. They are:

  • Vegetative reproduction
  • Sexual reproduction
Vegetative reproduction in Marchantia

Fragmentation

In this case, there is progressive death and decay of older parts of the thallus. As the death and decay reach the dichotomy, the two branches separate and each branch can develop into a new thallus.

Adventitious branch

Adventitious branch develops from the ventral surface of thallus or Arche gonophore. Adventitious branch can develop into a new thallus.

Gemma

Gemma is a special vegetative, multicellular, discoid structure found inside gemma cup. Gemma cup is cup-shaped structure found on the dorsal surface of thallus along the midrib. Gemma contains the multicellular discoid body and unicellular stalk. The body cell of gemma contains chloroplast and some of the cell also contain oil. There is also the presence of rhizoidal which can develop into rhizoids. The body of gemma is several layer thick at the margin. After maturity, gemmae come out from the gemma cup. When gemma reaches the suitable substratum, new thallus can be developed from the each lateral notch. So, two thalli can be developed from single gemmae.

  • It is kept in kingdom Plantae because it has the autotrophic mode of nutrition and cellulosic cell wall.
  • Gametophytic plant body of Marchantia is leafy, green and thallus. Type of thallus is prostrate, dorsoventrally flattened and dichotomously branched.
  • Apical part of the thallus contains small groove called apical notch which helps in further growth and development of thallus.
  • Ventral surface of the thallus is light green in color. It bears rhizoids and scales. Rhizoids are unicellular, unbranched and colorless.
  • Adventitious branch develops from the ventral surface of thallus or archegoniophore. Adventitious branch can develop into a new thallus.
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