Chemical Tests; flame test, positive and negative ions test Edexcel Internati...
Pteridohyte 1
1. WELCOME TO THE WORLD OF PTERIDOPHYTE
N.SANNIGRAHI, ASSOCIATE PROFESSOR,
NISTARINI COLLEGE, PURULIA (W.B) 723101, INDIA
2. PTERIDOPHYTES----------?????
• A group of vascular cryptogams, non-flowering ,
dispersed spores experienced alternation of
generation having dominant saprophytic phase and
rudimentary gametophyte phase, mostly distributed in
the marshy areas, appeared in the time of the Silurian
period & diversified in the lower Devonian period of
geological era after the colonization of the land of
gametophyte directly from algae or from bryophytes
as per another school of thought, more than 13000
species across the globe of which a major shares
extinct in nature during the passage of evolution.
3. CHARACTERS OF PTERIDOPHYTES
• Primitive land vascular plants both living( Lycopodium,
Selaginella, Equisetum etc.) and fossils( Rhynia,
Asteroxylon, Zosterophyllum etc.)
• Grow in cool and shady habitat though few are xerophytic
( S.rupestris) & many are aquatic( Azolla, Salvinia,
Marsilea)
• Adult plant body is sporophyte differentiated into roots,
leaves & stem. Rhizoids( Psilotum) & rhizophores(
Selaginella) are also reported
• Mature sporophyte are independent, though at the early
stage of development partially of completely dependent o
gametophytes
• Vascular systems with xylem & phloem, stele may be
protostele( Ectophloic, endophloc & amphiphloic) or
Siphonostele( Solenostele & Dictyostele) present.
4. Characters----
• Leaves may be simple, minute and sessile(
Lycopodium) or petiolate and megaphilous as in the
members of Filicinae.
• Reproduction through spores borne in sporangia
develop either in the ventral surface or in axil leaves(
sporophylls) either eusporangiate(group of superficial
cells, Selaginella) or leptosporangiate manner(intial
single cell, Marsilea)
• Plants may be homosporous or
heterosporous(Microspores & Megaspores)
• Gametophyte body is prothallus developed from
haploid(n) spores
5. Characters-----------
• Prothallus is multicellular, independent autotrophic
bear both sex organs-antheridia & archegonia
• Water needed in fertilization to form 2n zygote
• Zygote gives the saprophytic plant body
• Alternation of generation is the essential part of life
cycle. Most of the part of the life cycle is diploid as
the saprophytic part is predominant but the
gametophyte part represented by the prothallus is an
important part represented by haploid state .
7. CLASSIFICATION
• On the basis of presence or absence of seeds,
taxonomists placed the vascular plants –Pteridophyta
& spermatophyta.According to traditional system of
classification, the pteridophytes are divided into the
following classes followed by lower hierarchical taxa
like orders, families , genus, species etc.
• Division Pteridophyta
• i. Class- Psilophytineae
• Order- Psilotales,e.g Psilotum
• Order- Psilophytales e.g Rhynia
• 2.Class-Lycopodineae
8. Classification
• Order- Lycopodiales eg Lycopodium
• Order- Isoetales e.g Isoetes
• Order- Lepidodendrales e.g Lepidodendron
• 3.class Equisetineae
• Order- Equisetales represented by Equisetum
• Order- Sphenophyllales represented by
Sphenopmyllum
• 4.Class – Fillicineae
• Order- Filicales e.g Dryopteris
• Order Marattiales represented by Marattia
• Order Ophioglossales represented by Ophioglossum
& Botrychium
9. Classification
• Order- Osmundales represented by Osmunda
• Order-Fossil orders
This is the traditional system of classification which is being
generally introduced for the easy identification of the
pteriophytes. Besides, there are number of systems that
have been proposed from time to time in this regard as far
as the classification is concerned. The most popular
systems in this regard are ICBN Recommendations where
the name of the division end with suffix phyta,
subdivision by phytina, class by opsida. Smith (1955)
divided Pteridophyta under 4 divisions- Psilophyta,
Lepidophyta, Calamophyta & pterophyta. The wide
accepted system of classification is as follows.
