Wednesday, 26 May 2021

The root and stem have well developed vascular system

 The root and stem have well developed vascular system



Anthocerotales. According to them, both bryophytes and hypothetical aichegoniate land plants along different lines. pteridophytes have evolved from a common group of Pteridophyte Characteristic Features of Pteridophyta :

 The plant body is sporophytic, differentiated into root, stem and leaves. They range from annuals (e.g., Azolla, Salvinia) to large tree-like perennials (e.g., Angiopteris, Osmunda).

 Members (e.g., Azolla, Isoetes, Marsilea, Salvinia, Fig. IB, F) are aquatic, usually occurring in permanent ponds. Primary roots are ephemeral and are soon replaced by adventitious roots. The root has a permanent growing apex.

 Except for some woody ferns (e.g.. Angiopteris, Marattia, most pteridophytes have herbaceous stem. small and sessile (e.g. Lycopodium, Selaginella, or large, petiolate and compound (e.g. ferns). On the basis of eat structure, pteridophytes are classified into.

The root and stem have well developed vascular system, composed of xylem and phloem. But stems of few living pteridophytes (e.g., Botrychium, Isoetes) do show secondary growth regularly. Te.g., Lycopodium, Selginella), The stělě is a siphonostele (e.g., Equisetum, Ophioglossum pendulum, Botrychium).

In homosporous species, the development of gametophyte is exosporic (i.e., the gametophyte develops outside the spore wall), whereas in heterosporous species it is endosporic (i.e., the gametophyte develops within the spore wall).dictyostele (e.g., Pteris, Nephrolepis, Polystichum) or polycyclic (e.g., Angiopteris, Marattia). dictyostele (e.g., Pteris, Nephrolepis, Polystichum) or polycyclic (e.g., Angiopteris, Marattia). 

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