Pteridophyta: Did you ever think, what we initially see when we go to a forest full of trees? The first thing that catches our eyes is the green ferns which are in ample. These ferns are examples of Pteridophytes. Pteridophyta is also called vascular cryptogams, and they have more than \(12000\) species on this earth. Pteridophytes are the only non-flowering seedless plants having vascular tissues. Pteridophyta is classified into four main classes namely, Psilophyta, Lycophyta, Arthrophyta, Filicophyta. In this article, we will provide detailed information about Pteridophyta. Scroll down to read more!

Study About Class Pteropsida Fern Here

Define Pteridophyta

“Pteridophytes are seedless, vascular cryptogams. They reproduce by means of spores and can reach to the tree-like heights (\(30-40\) feets)” (Source: Arihant Biology Handbook)
The term “Pteridophyta” was given by Ernst Haeckel in the year \(1866\). Pteridophytes are considered as the first land plants with a well-developed vascular system. The Greek word “Pteron” means feather and “Phyton” means plants.

What are the Characteristics of Pteridophyta?

The Pteridophyta shows the following characteristics:

1. Habitat: They are terrestrial, grow well in moist and shady places. Some grow well in open, dry areas like Selaginella lepidophylla (resurrection plant) grow well in xerophytic conditions. Marsilea, Azolla are an example of aquatic pteridophytes. Some are epiphytes like Ophioglossum pendulum. Lygodium is a climbing fern.

2. Plant Body: The main plant body is sporophyte and differentiated into true roots, stem, and leaves.

3. Stem: In most cases, the branches are herbaceous, and some are woody. Some forms have dichotomously branched stem, while some forms have a monopodial stem.

4. Root: Roots are simple and arise adventitiously along the rhizomes near the base of the stems.

5. Leaves: They show three types of leaves like scale, small sessile and large petiolate compound. The Ferns leaves show circinate vernation (the young leaves are coiled inward).

6. Vascular Tissues: The vascular tissues are well developed. The xylem is mainly composed of tracheids, and xylem vessels are absent. The phloem is consisting of sieve cells, phloem parenchyma, and companion cells are not present.

7. Reproduction

a. Reproduction involves both vegetative and sexual types.
b. They mainly reproduce by spores as they are flowerless and seedless.
c. The spores are produced inside unique structures called sporangia.
d. Sporophylls are the specialized leaves that contain sporangia.
e. In most cases, the sporophyll may be aggregated to form a compact structure called strobili or cones (Selaginella, Lycopodium and Equisetum).
f. The development of sporangia may be eusporangiate or leptosporangiate.
g. The sporophyte plant may be Homosporous (producing only one type of spore) or Heterosporous (having two different kinds of spores, i.e., microspores and megaspores).
i). Selaginella, Azolla, Marsilea are heterosporous ferns.
h. A spore after germination develops into a small gametophyte called prothallus.
i. The prothallus bears sex organ, namely antheridia (male sex organ) and archegonia (female sex organ), producing male and female gametes, respectively.
j. Water is needed for the fertilization process.
k.The diploid zygote develops into an embryo, which slowly differentiates into a sporophyte \((2n)\).
l. Here, the embryo develops inside the female gametophyte plant, as the seeds develop in Phanerogams, which is considered an essential step in evolution.

Pteridophyta Classification

The four classes of Pteridophyta are as follows:
1. Psilophyta
2. Lycophyta
3. Arthrophyta
4. Filicophyta

Flow chart of Pteridophyta:

1. Psilophyta (Psilopsida)

a. These are the most primitive pteridophytes.
b. They have no roots.
c. Rhizoids are present instead of roots.
d. They have lateral appendages like scales or leaves, which are spirally arranged.
e. They are homosporous.
f. They have multiflagellate antherozoids.
g. Examples: Psilotum

2. Lycophyta (Lycopsida)

a. The plant body has roots, stems, and leaves.
b. They have microphyllous leaves.
c. They are homosporous as in Lycopodium or heterosporous in Selaginella.
d. These are also known as club mosses.
e. Examples: Lycopodium, Selaginella

3. Arthrophyta (Sphenopsida)

a. The plant body has roots, stems, and leaves.
b. They have joined nodes and internodes in the stem.
c. They contain small, scaly leaves, which are arranged at nodes in whorls.
d. They are also known as horsetails.
e. Equisetum is the only living genus of this class.
f. They are homosporous.
g. Examples: Equisetum

4. Filicophyta (Pteropsida)

a. The plant body has roots, stems, and leaves.
b. They have pinnately compound and circinate leaves.
c. These are present in all kinds of habitats.
d. They are both homosporous and heterosporous.
e. They are also known as ferns.
f. These are highly evolved and the largest group of pteridophytes.
g. Examples: Pteris, Dryopteris

Pteridophyta Life Cycle

1. Pteridophytes exhibit alternation of generation. The life cycle of Pteridophyte includes an alternation of diploid sporophytic generation with a haploid gametophytic generation. 
2. The sporophytic generation is the dominant phase in the life cycle of Pteridophyta. 
3. The sporophytic generation is diploid, photosynthetic and is independent of the gametophyte.
4. The sporophyte forms spores inside the sporangia after meiosis.
5. The spores germinate to give rise to the gametophyte called Prothallus. The prothallus is of two types monoecious and dioecious.
6. The gametophyte bears the male sex organs antheridia and female sex organs archegonia.
7. The antheridium produces many ciliated antherozoids.
8. In the process of fertilization, water is required as the antherozoids travel to the archegonia.
9. The zygote is formed by fertilization between the male and female gametes.
10. The zygote gives rise to the sporophyte.
11. The sporophyte and gametophyte both are morphologically distinct, independent, and living.
12. The life cycle pattern followed by Pteridophyta is called Diplo-haplontic.

Fig: Life Cycle of Pteridophyta

Pteridophyta Examples

A few important examples of Pteridophyta are:
1. Selaginella
2. Lycopodium
3. Equisetum
4. Pteris
5. Marsilea
6. Silver fern
7. Dryopteris
8. Whisk fern
9. Azolla
10. Ophioglossum
11. Dicksonia
12. Adiantum
13. Salvinia

Fig: Psilotum

Fig: Lycopodium

Fig: Equisetum

Fig: Fern

Importance of Pteridophyta

The importance of Pteridophyta are given below:
1. It is a source of food for animals.
2. Ferns protect soil from erosion.
3. Azolla is used as a biofertilizer.
4. They have medical value.
5. Club mosses are used to make industrial chemicals.
6. Ferns are used in decorations.
7. Pteridium leaves are used to make green dyes.

Pteridophyta – Affinities

Pteridophyta show affinities with Bryophyta:
1. Both show terrestrial habits.
2. Sporic reproduction is found in both groups.
3. Male and female reproductive organs, antheridia and archegonia, are similar in shape.
4. Antherozoids or sperms are flagellated.
5. Both require water for fertilization.
6. They show alternation of generations in their life cycle.
7. Both show sporic meiosis.

Difference Between Pteridophyta and Bryophyta

These are the following differences between Pteridophyte and Bryophyta:

Bryophyta	Pteridophyta
The plant body is haploid and gametophytic.	The plant body is diploid and sporophytic.
The sporophytic generation is completely or partially parasitic on the gametophyte.	Both sporophytes and gametophytes have an independent existence.
The Plant body may be thalloid (like liverworts) or with leafy appendages (in mosses).	The plant body is differentiated into roots, stems and leaves.
Vascular tissue is absent.	Vascular tissue is present. Vessels are not present in the xylem.
Only one type of spores are formed (all are homosporous).	Some genera evolved the formation of two types of spores, i.e., heterospory.

Did you Know?

1. Ferns evolved on earth for \(360\) million years.
2. Smallest fern on earth is Azolla caroliniana (Size \(0.5 – 1.5\,{\text{cm}}\)). It is an aquatic fern.
3. Tallest fern is Cyathea Australis (Size \(20\,{\text{mts}}\)).
4. Ophioglossum reticulatum contains the highest chromosome number (\(1440\) or \(720\) pairs).
5. Many dinosaurs ate ferns as their food.

Summary

Thus, in nutshell, we can say that Pteridophyta is one of the oldest groups of plants present on this earth. They grow in terrestrial habitats. They are also called one of the first “true” plants to adapt to life on land. Moreover, they are the first land plants with a well-developed vascular system. Ferns, which are one of the examples of pteridophytes, are abundantly available around us. The characteristics of Pteridophyta are habitat, plant body, stem, roots, leaves, vascular tissues, and reproduction.

FAQs on Pteridophyta

Q.1. What are the characteristics of pteridophyte?
Ans: The characteristics of pteridophyte are plant body, stem, roots, leaves, and vascular tissues.

Q.2. What is division Pteridophyta?
Ans: The division Pteridophyta is a heterogeneous group of plants that encompasses ferns and horsetails.

Q.3. What are the four classes of Pteridophyte?
Ans: The four classes of pteridophytes are Psilopsida, Lycopsida, Sphenopsida, and Pteropsida.

Q.4. What is the difference between bryophytes and pteridophytes?
Ans: The Bryophytes have leaf-like appendages, whereas, the pteridophytes have roots, stems and leaves. The sporophyte in Pteridophytes are autotrophic and are completely independent of the gametophyte. The gametophyte in the Bryophytes are dominant and sporophytes depends on the gametophyte.

Q.5. What is the life cycle of pteridophytes?
Ans: The life cycle of pteridophytes shows an alternation of diploid saprophytic generation with haploid gametophytic generation. The sporophytic generation is dominant in the life cycle. The sporophyte and gametophyte both are morphologically distinct, independent, and living. Thus, they show diplo-haplontic life cycle.

Q.6. Why are pteridophytes called ‘snakes of plant kingdom’?
Ans: The pteridophytes are called ‘snakes of plant kingdom’ because they evolved after Bryophyta, which are called the amphibians of the plant kingdom.

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