What are the Trasmigration of Plants from Water on to land ?

Answer Posted / guest

Land plants are evolved from the aquatic ancestors. Aquatic
plant have few problems to solve to adopt life on land.

1. Absorption of water.

2. Retention of water.

3. Absorption of CO2 for photosynthesis. We have two
distinct groups of land plants.

(a) Mossess and liverworts i.e. non-vascular plants.

(b) Vascular plants.

Green algae show some of the characters which have also
exhibited by mosses and liverworts.

Mossess and Liverworts possess these characters.

1. A compact multicellular body and ability to conserve.

2.Modification of photosynthetic tissue for absorption of CO2

3. Special structure for absorption H2O.

4. Hetrogomy.

5.Preotection of Generalion.

6. Alternation of Generalion.

7.Formation of Embroys.

Green algae show multicellular body, hetrogamy, protection
of Repd. Cells and alternation of Generalion.

In unicellular chalamydomnas we see palmella stage which
resembles the multicellular volvox colony.

In Ulthorix oedogonium etc. lowermost cell of filament
becomes the holdfast which attaches the plant to substratum,
is also an important evolutionary step in migration of
plants from H2O to land. It is of great advantage for and
plants to have multicellular body exposed to aquatic
environment, thus whole cell surface of chalmydomnas absurd
H2O carbonates etc. If this unicellular plant lives drying
vegetative cell would soon die.

If these singly called plants cannot live on land, then it
is difficult for multucelluar bodies to live on land but
this does not happen so. In multicellular bodies only a
small percentage have surfaces directly expose to air but in
unicellular chalydomnas whole cell surface of plant is
exposed to air and thus relative amount of cell surface that
expose to air from which evaporation occurs in multicellular
organism is less than that of unicellular one. Rete of
evaporation is also reduced by present of catin in the
mosses and liverworts.

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