TYPES OF PTERIDOPHYTES

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TYPES OF PTERIDOPHYTES 

In previous post we discussed about PSILOPSIDA:-



LYCOPSID:-

  • Known as club mosses
  • Plant bodies is differentiated into root, stem and leaves.
  • Sporongia are formed on sporophytes.
  • This sporophyte are not scattered on stem instead they are present in group at the tip of plant.
  • The group is called strobilus or cones.
For e.x:- Lycopodium, Selaginalla.

SPHENOPSIDA:-
  • In thos case horsetailcare included.
  • The plant bodies of horsetails is differentiated into root, stem and leaves
  • Silica is present in the epidermis of stem and leaves. Due to this surface of plants become rough. If two horsetails plants collide then they are dangerous chances of fire in the forest.
  • Cones is formed at the apical part of the aerial stem. For eg:-Equisetuon


PTEROPSIDA:-
  • Largest group of pteridophyta, commonly known as ferms.
  • Ferms are megophylloud and thus leaf are known as fronds (pimately leaf).
  • Multicellular brown hair are present on young leads and the young stem of ferm which are called Ramentia.
  • They are for protection and to decrease the losses of water during transpiration.
  • Each and every leaf of ferms formed sporangia at the time of the reproduction therefore cones are not produce in fern.
E.x:-Marcillia, Dryopteris, Pteridinium, (Adiantum)-walking ferm or maiden are ferm/smallest pterdidophyta and biofertiliser.
Saluinia:-Aquatic in nature.

HETEROSPORIC IN PTERIDOPHYTA

●Occurence of two types of spores:-
1. Small (microspore)
2. Large (macrospore/megaspores)

HETEROSPORY IN PTERIDOPHYTA
  • A very few genera are heterosporous on pteridophyta E.x. selaginella, saluinia, azolla, marcillia
  • In this plants microspheres formed male gametophyte and megastores formed at female gametophyte. Male gametophyte contains male sex organ   and male gamete which comes outside the microsporangium.
  • Female gametophyte contains female sex organ which contain female gamete inside the megasporangium on the parental sporophyte which are retained in magasporangium for variable periods.
  • After fertilisation - zygote - embryo is formed. Embryo essentially outside the megasporangium. So, seeds could not be in pteridophyte but the heterospore is formed in them which is a very important stage in evolution of seed habits in higher plants.
Note:- In some pteridophyte prothallus is saprophytic.
2. In heterosporous pteridophyte like selaginella and saluinia gametophyte are not formed prothallus because it is very reduced.




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