•Pteridophytes are the largest group of living primitive vascular plants.
•These are the first land plants with vascular tissue (xylem and phloem)
CHARACTERSTICS OF PTERIDOPHYTES
•1.The main plant body of pteridophytes is diploid sporophyte which is differentiated into true root stem and leaves.
•Stem: It may be erect above ground or underground rhizome.
Leaves: Leaves may be minute called microphyllous or large called megaphyllous.
2. Vascular bundles are present in organized groups or steles.
•3.Reproduction takes place by spores produced inside sporangia. The leaves bearing sporangia are called sporophyll.
•But in some species the sporangia are born in the axile of stem and leaves as in Selaginella.
•And in some special structure as fertile spikes sporangiophore or sporocarp. Ex.Ophioglossum ,Equisetum, Marsilea.
•4.Plant may be homosporous produce single type of spores Ex Lycopodium, Pteridium
•Or heterosporous that produce two type of spores smaller microspores and large megaspores.
5.Spore germinate to form haploid gametophyte Prothallus .
Homosporous species produce monoecious prothallus ( male and female gametangia on same prothallus)& Heterosporous produces dioecious prothallus (male and female gametangia on different prothallus).
6. Sexual reproduction is oogamous type .
Antheridia and archegonia are born on prothallus. Antheridia reaches the venter are fertilize the egg where zygote form the zygote divide inside the venter to form embryo which takes its nourishment from prothallus.This embryo germinate to form sporophyte
Examples of pteridophytes
•Lycopodium is known as club moss it is used in curing rheumatism & liver kidney disorders.
•Selaginella : (spike moss) These plants are capable of flexing their branches & roll to assume the shape of balls under prolonged dry conditions but when dipped in water or moistened they resume their normal form hence called resurrection plants.
•Equisetum :(Horsetail or scouring rushes.
•Adiantum is known as walking fern because it propagate vegetatively by its leaf tips. It is also called maiden hair fern because of beautiful black petiole of leaves.
•Azolla is water fern.
•Anthelmintic drug is obtained from rhizome and petiole of Dryopteris.