Pteriduphytes 2

pteridophytes

1. COMPARATIVE MORPHOLOGY,STRUCTURE,ECOLOGY AND PHYLOGENY OF THE GROUPS “ SPHENOPSIDA,PTEROPSIDA” PRESENTED BY… ATHIRA.S

2. PTERIDOPHYTES Vascular cryptogames The name 1 st introduced by Haeckel(1866) Occupy a position in between bryophyts an gymnosperms Plant body is sporophytic Terrestrial,aquatic an few are xerophytic

3. PTERIDOPHYTES ARE CLASSIFYED INTO 4 GROUPS Psilopsida Lycopsida Sphenopsida Pteropsia

4. SPHENOPSIDA Attained their maximum development in carboniferous flora Only single genus equisetum is living In carboniferons period grew to 25m Spenopsida vegetation of the carboniferons period almost extinct(expect equisetum)during unfavorable climate of the Permian period Equisetum is one of the oldest living genus of vascular plant in the world today

5. features Equisetum only living and 16 fossils Sporophyte:root,stem&leaves Stem:- articulated,branched,nodes&inter nodes,in some extinct forms secondary thickening were observed Leaves:-small scally arranged in nodes in whorls Sporangia:-sporangia develops on sporangiophores & form strobilus Spore:-members are homospores,extinct forms are heterospores Antherozoids are multiflagellate Embryo lacks suspensor

6. REPRODUCTION Spores develop within sporangia and it borne on sporangiophore Mature sporangia are sac-like attached to pellate disc of sporangiophore Mature sporangia has 2 layered wall Sporangium matures,the axes elongates,sporangiophores separate Sporangium dries,shrink & sporangium reptures & spores releases Spore germinates to a prothallus Antheridia and archegonia are present Protogynous Archegonia has small neck and swellan base Antherozoides are formed inside the antheridia At maturity, neck canal cells &venter cells of archegonia desentegrates Desentegrate mass attract antherozoides towards the neck Only one antherozoid fuses with egg to form a diploid zygote

7. Sphenopsida is divided into 5 orders Calamitales Sphenophyllales Equisetales Hyeniales pseudoborniales

8. SPHENOPHYLLALES Fossil order of sphenopsida Members appeared 1 st in upper Devonian The plant body is sporophytic Stem divisible into nodes and inter nodes Leaves simple wedge shaped and divided dichotomously into small lobes Plant has well organized strobilus Sphenophyllales are divided into2 families,sphenophyllaceae,cheirostrobaceae

9. SPHENOPHYLLUM Fossil genus Appeared in upper Devonian&extinct in Triassic period Stem were delicate and deviseble into nodes and inter nodes Leaves whorle arrangement 6-18 leaves present in each nodes Heterophyllous nature

10. PTEROPSIDA Commonly known as ferns Fossil plants Sporophyte differentiated into root,stem&leaves Leaves are large( megaphylls )compound stem is protostelic,siphonostelic or dictyostelic Limited secondary growth Sporangia are thick or thin walled Homosporous or hetrosporous,borne in unmodified foliage or specialized fertile leaves They are either terminal in leaf segment Specialized structure sporocarp Sporangia either are single or form sori or fues to form synangia Antherozoids are multiflagllate

11. PETROPSIDA IS DEVIDED INTO 6 ORERS Cladoxylales Coenopteridales Protopteridales Marattiales Ophiglossales filicales

12. OPHIOGLOSSALES Include 3 genera:- ophioglossum,botrychium and helminthostachys Sporophytic plant body is herbaceons and rhizome,is short and flesh Thick fleshy roots Sporangia develop in the fertile axis The sporangia are large and marginaly placed Surronded by many-celled thick sporangial wall A spore develops into subterranean mycorrhizic and tuberous prothallus Prothalli bear the sex organ

13. OPHIOGLOSSUM Class : pteropsia Subclass: eusporangiatae Order : ophioglossales Family : ophioglossaceae Genus : ophioglossum World wide distribution Epiphytes,saprophyte,aquatic Sporophytic plant body-short and errect rhizome

14. Roots :- many thick adventitions roots on the rizhome Roots hairs absent Mycorrhizal in nature Leaves:-borne in an irregular spiral on stem Most species produce only one leaf in on growing season but in some species 4-5 leaf are produce reticulate venation and stipule present

15. REPROUCTION Spore bearing organs:-sporangia borne on a fertile spike Spike has sterile stalk Sporangia are embedded in either side of spike Mature sporangium large fused with leaf Spore mother cells functional and develop into spore tetrad Sporangial development is eusporngiate Sporogenous cells function as for mother cells Devide meiotically to form haploid spores Dehiscence of sporangium through transverse cleft in each sporangium Spore germinate to prothali

16. Prothali has antheridia and archegonia Antheridium development start from single superficial cell of the gametophyte 1 st periclinal division form outer jacket and inner androgonial cells androgonial cells develops to androcyte mother cells& into antherozoids Archegonium development start from single superficial archegonial initial of the gametophyte After further division archegonial develop Developed archegonium has 4 celled neck,venter canal cell and egg At the maturity,primary canal and venter canal cells disintegrate The neck open the archegonium get ready for fertilization

17. Systematic position of ophiglossum Lack any fossil record , this order is grouped with ferns Special type of plant body bearing single leaf of sterile & fertile segments Vessels are present Mycorrhizic roots Root hairs absent

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