27Pteridophyta

📚
PTERIDOPHYTA
▢ General Characters:
❖ Position: 1st vascular land plant
❖ Main Plant Body: Diploid \((2n)\) + sporophytic
❖ Spore Condition:
  • •
    Homosporous
  • •
    Heterosporous
❖ Common Names:
  • •
    Reptiles of plant kingdom
  • •
    Botanical snakes
▢ Vascular Bundle:

Table 1: Vascular Features

Feature
Status
Note
Cambium
Absent
Secondary growth absent
Exception
Isoetes
Secondary growth present
Phloem companion cell
Absent
-
Sieve tube
Absent
-
Sieve cell
Present
-
▢ Habitat:
❖ General Habitat: Land
❖ Aquatic Exceptions:

Table 1: Aquatic Pteridophytes

Plant
Important Points
Azolla
  • •
    Smallest pteridophyte
  • •
    Leaf → biofertilizer
Marsilea
Aquatic pteridophyte
Salvinia
Rootless pteridophyte
▢ Size:
❖ General: Small herb-like plants
❖ Exceptions:

Table 1: Large Pteridophytes

Plant
Feature
Alsophila
Largest / tallest pteridophyte
Cyathea
Tree fern
▢ Plant Body Differentiation:
❖ Root:
  • •
    Generally adventitious
❖ Stem:
  • •
    Usually underground rhizome
❖ Root-like Terms:

Table 1: Rhizo- Terms

Term
Meaning
Found In
Rhizomorph
Root-like absorptive structure
Fungi
Rhizines
Root-like anchoring structure
Lichen
Rhizoid
Root-like structure
Bryophyta
Rhizophore
Axis between root and stem
Selaginella
◉ Rhizophore Note:
  • •
    Organ of sui generis
  • •
    Sui generis → unique / one of its own kind
❖ Leaf:

Table 1: Leaf Types

Leaf Type
Function
Tropophyll
Photosynthetic leaf
Sporophyll
Spore-producing leaf
◉ Sporophyll:
  • •
    Contains sporangium
❖ Sporangium Types:

Table 1: Leptosporangiate vs Eusporangiate

Feature
Leptosporangiate
Eusporangiate
Origin
Single initial cell
Group of cells
Evolution
Advanced
Primitive
Examples
  • •
    Dryopteris
  • •
    Pteris
  • •
    Azolla
  • •
    Selaginella
  • •
    Equisetum
  • •
    Marsilea
  • •
    Lycopodium
▢ Classification:

Table 1: Classes of Pteridophyta

Class
Spore Condition
Examples
Psilopsida
Homosporous
  1. Rhynia
    • •
      1st vascular plant
    • •
      fossil form only
      • Image 1
  2. Psilotum → living member
    3. Image 1
Lycopsida
Homosporous / Heterosporous
  1. Lycopodium → club moss
  2. Selaginella
    • •
      spike moss
    • •
      bird nest moss
    • •
      resurrection plant
    • •
      Sanjivani buti
      • Image 1
      Image 1
Sphenopsida
Homosporous
  1. Equisetum → horsetail
    2. Image 1
Pteriopsida / Filicopsida / Filicinae / Ferns
Homosporous / Heterosporous
  1. Dryopteris
    2. Image 1
  2. Pteris → maidenhair fern
    3. Image 1
  3. Adiantum caudatum → walking fern
    4. Image 1
    Image 1
📚
DRYOPTERIS AND PTERIS
Image 1
Image 1
Image 1
▢ Plant Body:
❖ Dominant Generation: Diploid sporophyte
❖ Habit: Fern plant with an underground rhizome, roots and large compound leaves.
▢ Leaf:
❖ Frond:
◉ Definition: The leaf is large, feather-like and pinnately compound, and is called a frond.
❖ Ramenta:
◉ Definition: Brown, hair-like or scaly structures present on the rhizome and rachis.
◉ Colour: Brown
❖ Circinate Vernation:
◉ Definition: The young leaf remains coiled or twisted during development.
◉ Synonym: Circinate ptyxis
▢ Reproduction:
❖ Vegetative Reproduction:
◉ Methods:
  • •
    Fragmentation
  • •
    Apogamy
◉ Fragmentation: Fragments of the rhizome develop into new sporophytic plants.
◉ Apogamy:
◈ Definition: Formation of a sporophyte directly from the gametophyte without fertilization.
◈ Ploidy: The apogamous sporophyte is haploid.
❖ Sexual Reproduction:
Image 1
◉ Sporophytic Phase:
◈ Plant Nature: The main fern plant is a diploid sporophyte.
◈ Sporangia: Sporangia are produced on the leaves.
◈ Sorus:
■ Definition: A group or cluster of sporangia is called a sorus.
■ Location: Usually present on the lower surface of fertile fronds.
◉ Protection of Sorus:
◈ Dryopteris:
■ Indusium: The sorus is protected by a kidney-shaped membranous outgrowth called the indusium.
◈ Pteris:
■ Coenosorus: The sporangia form a continuous linear sorus called a coenosorus.
■ False Indusium: The coenosorus is protected by the reflexed margin of the leaf, called a false indusium.
◉ Sporangium:
◈ Type: Leptosporangiate
◈ Spores:
■ Nature: Homosporous
■ Ploidy: Haploid
◈ Annulus:
■ Definition: A ring of thick-walled hygroscopic cells present in the sporangial wall.
■ Function: Helps in rupture of the sporangium and dispersal of spores.
◈ Stomium:
■ Definition: A thin-walled region of the sporangium through which dehiscence occurs.
◈ Dehiscence: Drying of the annulus creates tension, causing the sporangial wall to break at the stomium and release spores.
◉ Spore Germination:
◈ Sequence:
  1. Haploid spores are released from the sporangium.
  2. Each spore germinates under favourable conditions.
  3. A green, heart-shaped prothallus is formed.
  4. The prothallus develops male and female reproductive organs.
Image 1
◉ Prothallus:
Image 1
Image 1
◈ Definition: The prothallus is the independent haploid gametophyte of the fern.
◈ Shape: Heart-shaped
◈ Colour:
■ Prothallus: Green
■ Rhizoids: Brown
◈ Nature:
  • •
    Haploid
  • •
    Green and photosynthetic
  • •
    Heart-shaped
  • •
    Dorsiventral
  • •
    Monoecious
  • •
    Bears both antheridia and archegonia
◈ Apical Notch: A notch present at the anterior end of the prothallus.
◈ Rhizoids:
■ Location: Ventral surface
■ Colour: Brown
■ Function:
  • •
    Attachment
  • •
    Absorption of water and minerals
Image 1

Table 1: Antheridium and Archegonium of Fern

Feature
Antheridium
Archegonium
Sex organ
Male
Female
Location
Near the rhizoids on the posterior region of the prothallus
Just below the apical notch on the cushion region
Shape
Dome-shaped
Flask-shaped with a bent neck
Product or contents
◉ Male Gametes:
  • •
    Multiflagellate
  • •
    Coiled
  • •
    Motile
◉ Archegonial Contents:
  • •
    One egg cell
  • •
    One venter canal cell
  • •
    One binucleate neck canal cell
Maturity
Matures earlier
Matures later
◉ Protandry:
◈ Definition: The antheridia mature before the archegonia on the same prothallus.
◈ Significance: Promotes cross-fertilization and reduces self-fertilization.
◉ Chemotaxis:
◈ Definition: Male gametes move toward the archegonium in response to a chemical stimulus.
◈ Chemotactic Substance: Malic acid
◉ Fertilization:
◈ Type: Internal
◈ Requirement: A thin film of water is required for movement of the male gametes.
◈ Sequence:
  1. Antheridium releases multiflagellate male gametes.
  2. Male gametes swim toward the archegonium due to malic acid.
  3. One male gamete fuses with the egg inside the archegonium.
  4. A diploid zygote is formed.
◉ Embryo Formation:
◈ Zygote: The diploid zygote develops into an embryo.
◈ Embryo: The embryo differentiates into a young diploid sporophyte.
◈ Young Sporophyte: Initially dependent on the prothallus for nutrition.
◈ Adult Sporophyte: Later becomes independent and develops roots, rhizome and fronds.

Table 1: Sorus in Dryopteris and Pteris

Feature
Dryopteris
Pteris
Type of sorus
Distinct rounded sori
Continuous linear coenosorus
Position
Lower surface of the frond
Along the margins of the pinnules
Protective structure
True indusium
False indusium
Nature of protective structure
Kidney-shaped membranous outgrowth
Reflexed margin of the leaf
Image 1
▢ Life Cycle Sequence:
  1. The diploid sporophyte produces sori on fertile fronds.
  2. Each sorus contains numerous leptosporangiate sporangia.
  3. Meiosis inside the sporangia produces haploid homospores.
  4. The annulus helps the sporangium break at the stomium.
  5. Released spores germinate into green, heart-shaped prothalli.
  6. The monoecious prothallus bears antheridia and archegonia.
  7. Antheridia produce multiflagellate, coiled male gametes.
  8. Archegonia contain the egg cell.
  9. Water permits male gametes to swim toward the archegonium.
  10. Fertilization forms a diploid zygote.
  11. The zygote develops into an embryo.
  12. The embryo forms a young sporophyte.
  13. The young sporophyte becomes an independent adult fern plant.
Important Points
❖ Dominant Generation: Diploid sporophyte
❖ Gametophyte: Green, heart-shaped prothallus
❖ Spore Type: Homosporous
❖ Sporangium Type: Leptosporangiate
❖ Sexual Condition: Monoecious and protandrous
❖ Chemotactic Substance: Malic acid
❖ Male Gamete: Multiflagellate and coiled
❖ Young Leaf: Shows circinate vernation
Q1.
Multiflagellate antherozoids are characteristic of:
📅CEE MBBS 2025
Q2.
A fern prothallus is:
📅CEE MBBS 2024B
Q3.
Unlike bryophytes, pteridophytes possess:
📅CEE BDS 2024
Q4.
Pteridophytes differ from bryophytes by possessing:
📅CEE Nursing 2024
Q5.
The sexual organs of ferns are borne on the:
📅CEE Nursing 2024
Q6.
Which fern is grown as an ornamental garden plant?
📅CEE Nursing 2024
Q7.
The gametophyte of most terrestrial ferns is:
📅CEE MBBS 2022
Q8.
Pteridophytes differ from bryophytes mainly in the presence of:
📅CEE MBBS 2021
Q9.
In Pteridium, circinate vernation is found in:
📅MOE 2008
Q10.
Which structure protects a group of sporangia in a fern?
📅MOE 2063
Q11.
The gametophyte of a typical fern is:
📅MOE 2002, 2057
Q12.
The male gamete of a typical fern is:
📅MOE 2055
Q13.
The leaf of a fern is commonly called a:
📅IOM 2003
Q14.
Which group is known as vascular cryptogams?
📅IOM 2002
Q15.
In typical ferns, sporangia are borne on the:
📅IOM 2000
Q16.
A common stele type in the rhizome of many advanced ferns is:
📅IOM 1999
Q17.
A seedless plant with true vascular tissues is classified as a:
📅IOM 1999
Q18.
Alternation of generations is also termed:
📅BPKIHS 2000
Q19.
Which statement about alternation of generations is incorrect?
📅BPKIHS 2003
Q20.
A stele with a solid central vascular core and no pith is called:
📅BPKIHS 2005
Q21.
Which plant is popularly called the resurrection plant?
📅BPKIHS (year incomplete in source)
Q22.
A sporangium developing from a group of initial cells is termed:
📅BPKIHS 2005
Q23.
Ferns differ from mosses in having a:
📅IE 2001
Q24.
In Selaginella, the ligule is found:
📅BPKIHS 2014
Q25.
Pteridophytes differ from bryophytes in possessing:
📅BPKIHS 2012
Q26.
Which feature distinguishes pteridophytes from bryophytes?
📅IOM 2013
Q27.
Vascular cryptogams belong to:
📅IOM 2015
Q28.
In a typical fern archegonium, which cell is described as binucleate before separating into two neck canal cells?
📅MOE 2014
Q29.
Which group has both gametophyte and sporophyte generally capable of independent existence?
📅MOE 2013
Q30.
Which plant group is called vascular cryptogams?
📅MOE 2013
Q31.
An apogamous fern sporophyte developing directly from a normal haploid gametophyte without chromosome doubling would be:
📅MOE 2012
Q32.
In ferns, antheridia and archegonia are usually produced on the:
📅MOE 2068
Q33.
Antherozoids of Pteridium are:
📅MOE 2010