Pteridophyta (Pteridophytes):

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  • Fern plants are pteridophytes and are seedless vascular plants, which contain vascular tissues but do not produce seeds. They are involved in transportation of fluids and reproduction process is carried by spores.

    Image shoiwng fern plant parts.

    Image Showing Fern Plant.

    Image shoiwng fern plant parts.

  • The members of pteridophyta are generally terrestrial mesophyte (Adiantum), rarely xerophyte (Adiantum sp.), halophyte (Acrostichum), epiphyte (Selaginella, Pleopeltis), amphibians (Marsilea) or hydrophyte (Azolla, Salvinia).

  • The plants possess vasculature and hence called vascular cryptogams. The xylem usually lacks vessels and there are no companion cells in phloem. The roots are adventitious in origin and the stem may be aerial or underground. The leaves may be microphyllous or megaphyllous. They may be simple or pinnate or palmate or absent. The fern fronds may be differentiated into pinnae and pinnules.

  • Reproduction involves production of spores inside special structures called sporangia which occur on the ventral surface of fertile leaves called sporophylls. Sporangia may sometimes be found in groups called sori. The plants may be homosporous; producing only one type of spore or heterosporous; producing two different types of spores; smaller microspores and larger megaspores.

  • The spores germinate to produce a haploid gametophyte, called prothallus. The homosporous pteridophytes produce bisexual gametophytes while heterosporous pteridophytes produce unisexual gametophytes. In gametophytes, reproduction is of oogamous type. The male sex organs are called antheridia and female sex organs are called archegonia. The gametes fuse and zygote develops into a diploid sporophyte.

  • Thus the life cycle includes an alternation of diploid sporophytic generation with a haploid gametophytic generation. Sporophytic generation is dominant in the life cycle.

  • Eichler in 1883 included pteridophytes under Cryptogamia but Engler in 1909 placed it under Embryophyta Asiphonogama. According to Eames (1936), Tippo (1942), the Tracheophyta consisting of four subdivisions; Psilopsida, Lycopsida, Sphenopsida and Pteropsida.

  • The pteridophytes are of great aesthetic value (Lycopodium, Adiantum, Nephrolepis, Lastrea, Schizaea, Cyathea etc.). Some species of Selaginella are called resurrection plants. Lycopodium sp. is of medical significance.

  • The formation of sporophyte from a gametophytic cell other than the egg without fertilization is called apogamy, e.g. Selaginella, Marsilea, Lastrea etc.