PTERIDOPHYTES
Meaning of Pteridophytes
Pteridophyta (Gr, Pteron = feather, phyton = plant), the name was originally given to those groups
of plants which have well developed pinnate or frond like leaves eg. ferns. Pteridophytes are
cryptogams (Gr. kruptos = hidden, and Gamos = wedded) which have well developed vascular
tissue.
Therefore, these plants are also known as vascular cryptogams or snakes of plant kingdom. They
are represented by about 400 living and fossil genera and some 10,500 species. Palaeobotanical
studies reveal that these plants were dominant on the earth during the Devonian period and they
were originated about 400 million years ago in the Silurian period of the Palaeozoic era. Earliest
known Pteridophyte is Cooksonia.
Scientific Classification of Fern (Example: Nephrolepis exaltata)
Kingdom: Plantae
Phylum (Division): Pteridophyta
Class: Polypodiopsida
Order: Polypodiales
Family: Nephrolepidaceae
Genus: Nephrolepis
Species: exaltata
Scientific name: Nephrolepis exaltata
General Characteristics
(i) Majority of the living Pteridophytes are terrestrial and prefer to grow in cool, moist and shady
places e.g., ferns. Some members are aquatic (e.g., Marsilea, Azolla), xerophytic (e.g., Selaginella
rupestris, Equisetum) or epiphytic (e.g., Lycopodium squarrosum)
(ii) Majority of the Pteridophytes are herbaceous but a few are perennial and tree like (e.g.,
Angiopteris). Smallest Pteridophyte is Azolla (an aquatic fern) and largest is Cyathea (tree fern).
(iii) Plant body is sporophytic and can be differentiated into root, stem and leaves.
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, (iv) Roots are adventitious in nature with monopodial or dichotomous branching. Internally usually
they are diarch.
(v) Stem is usually branched. Branching is monopodial or dichotomous. Branches do not arise in
the axil of the leaves. In many Pteridophytes stem is represented by rhizome.
(vi) Leaves may be small, thin, scaly (microphyllous e.g., Equisetum), simple and sessile (e.g.,
Selaginella) or large and pinnately compound (megaphyllous e.g., Dryopteris, Adiantum).
(vii) Vascular tissue is present in stem and root. It consists of xylem and phloem. Xylem consists
of tracheids only and phloem has only sieve tubes.
(viii) The steel is protostele (e.g., Rhynia, Lycopodium), siphonostele (e.g., Equisetum), dictyostele
Adiantum) or polycyclic (e.g., Angiopteris).
(ix) Cambium is absent; hence, they do not show secondary growth.
Reproduction in Pteridophytes:
(i) Reproduction takes place by means of spores which are produced inside sporangia.
(ii) The development of the sporangium may be leptosporangiate (sporangium originates from a
single cell) or eusporangiate (sporangium develops from a group of cells).
(iii) Sporangia may be borne either on stem or leaves. On the stem they may be terminal (e.g.,
Rhynia) or lateral (e.g., Lycopodium). On the leaves (sporophylls) they may be ventral, marginal
(Pteris, Adiantum) or dorsal (e.g., Polypodiceae). In Equisetum the sporangia are borne on special
structures called sporangiophores which constitute a cone. In Marsilea, Azolla, Salvinia sporangia
are produced in sporocarps.
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Meaning of Pteridophytes
Pteridophyta (Gr, Pteron = feather, phyton = plant), the name was originally given to those groups
of plants which have well developed pinnate or frond like leaves eg. ferns. Pteridophytes are
cryptogams (Gr. kruptos = hidden, and Gamos = wedded) which have well developed vascular
tissue.
Therefore, these plants are also known as vascular cryptogams or snakes of plant kingdom. They
are represented by about 400 living and fossil genera and some 10,500 species. Palaeobotanical
studies reveal that these plants were dominant on the earth during the Devonian period and they
were originated about 400 million years ago in the Silurian period of the Palaeozoic era. Earliest
known Pteridophyte is Cooksonia.
Scientific Classification of Fern (Example: Nephrolepis exaltata)
Kingdom: Plantae
Phylum (Division): Pteridophyta
Class: Polypodiopsida
Order: Polypodiales
Family: Nephrolepidaceae
Genus: Nephrolepis
Species: exaltata
Scientific name: Nephrolepis exaltata
General Characteristics
(i) Majority of the living Pteridophytes are terrestrial and prefer to grow in cool, moist and shady
places e.g., ferns. Some members are aquatic (e.g., Marsilea, Azolla), xerophytic (e.g., Selaginella
rupestris, Equisetum) or epiphytic (e.g., Lycopodium squarrosum)
(ii) Majority of the Pteridophytes are herbaceous but a few are perennial and tree like (e.g.,
Angiopteris). Smallest Pteridophyte is Azolla (an aquatic fern) and largest is Cyathea (tree fern).
(iii) Plant body is sporophytic and can be differentiated into root, stem and leaves.
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, (iv) Roots are adventitious in nature with monopodial or dichotomous branching. Internally usually
they are diarch.
(v) Stem is usually branched. Branching is monopodial or dichotomous. Branches do not arise in
the axil of the leaves. In many Pteridophytes stem is represented by rhizome.
(vi) Leaves may be small, thin, scaly (microphyllous e.g., Equisetum), simple and sessile (e.g.,
Selaginella) or large and pinnately compound (megaphyllous e.g., Dryopteris, Adiantum).
(vii) Vascular tissue is present in stem and root. It consists of xylem and phloem. Xylem consists
of tracheids only and phloem has only sieve tubes.
(viii) The steel is protostele (e.g., Rhynia, Lycopodium), siphonostele (e.g., Equisetum), dictyostele
Adiantum) or polycyclic (e.g., Angiopteris).
(ix) Cambium is absent; hence, they do not show secondary growth.
Reproduction in Pteridophytes:
(i) Reproduction takes place by means of spores which are produced inside sporangia.
(ii) The development of the sporangium may be leptosporangiate (sporangium originates from a
single cell) or eusporangiate (sporangium develops from a group of cells).
(iii) Sporangia may be borne either on stem or leaves. On the stem they may be terminal (e.g.,
Rhynia) or lateral (e.g., Lycopodium). On the leaves (sporophylls) they may be ventral, marginal
(Pteris, Adiantum) or dorsal (e.g., Polypodiceae). In Equisetum the sporangia are borne on special
structures called sporangiophores which constitute a cone. In Marsilea, Azolla, Salvinia sporangia
are produced in sporocarps.
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