General Characters of Pteridophytes PDF
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Uploaded by CommendableSard7063
Loyola College
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Summary
This document provides a general overview of the characteristics of Pteridophytes, including details on their reproduction, habitat, and life cycle. It explores the differences between homosporous and heterosporous types and the structure of sporophytes and gametophytes.
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GENERAL CHARACTERS OF PTERIDOPHYTES Primitive land vascular plants – Lycopodium, Selaginella, Equisetum and fossil vascular plants – Rhynia, Asteroxylon, Lepidodendron Club mosses, ferns and horsetails – common names Vascular cryptogams – no flowers or seeds for reproduction – ‘hidd...
GENERAL CHARACTERS OF PTERIDOPHYTES Primitive land vascular plants – Lycopodium, Selaginella, Equisetum and fossil vascular plants – Rhynia, Asteroxylon, Lepidodendron Club mosses, ferns and horsetails – common names Vascular cryptogams – no flowers or seeds for reproduction – ‘hidden’ – reproduction by spores Cool and shady habitat – few xerophytic (S. rupestris) and many aquatic (Marsilea, Salvinia, Azolla) Adult plant body is SPOROPHYTE differentiated into leaves, stem and roots – rhizoids (Psilotum) and rhizophores (Selaginella) reported Mature sporophytes INDEPENDENT – early stage of development partially or completely DEPENDENT on GAMETOPHYTE Vascular system – both xylem and phloem present – STELE either protostele (ectophloic, endophloic, amphiphloic) or siphonostele (solenostele, dictyostele) Leaves : simple, minute, sessile (Lycopodium) – microphyllous or petiolate and megaphyllous as in members of Filicinae Reproduction by SPORES formed in SPORANGIA – occur on ventral surface or axil of leaves (leaves bearing sporangia are called sporophylls) Homosporous (all spores of same size and structure) or heterosporous (microspore or megaspore) Development of sporangia: Eusporangiate type: Sporangia develop from a group of superficial cells (initials) – Eg. Selaginella Leptosporangiate type: Sporangia develop from a single cell (initial) – Eg. Marsilea Gametophyte is called PROTHALLUS – develops from HAPLOID spore Prothallus: multicellular, autotrophic (independent) structure - bearing both sex organs (antheridia and archegonia) Monoecious - male and female organs in same plant Dioecious – male and female organs in different plants WATER essential for fertilization – Formation of DIPLOID zygote Zygote gives rise to SPOROPHYTE Heterologous alternation of generations present - gametophyte is different from the sporophyte – morphologically
