Pteridophyta – Definition, Characteristics, Classification, Uses

Each organism in this world, whether it is a plant, an animal, or a microorganism(viruses, bacteria, unicellular eukaryotes), is unique in itself. This uniqueness of individuals forms the basis of the diversity among living organisms.

The term ” biodiversity ” is a combined form of “biological Diversity”. It is coined by Walter G.Rosen in 1986. A large variety of organisms or Terms used to refer to the number of varieties of plants and animals on earth is termed biodiversity. There are three types of biodiversity: genetic, species, and ecological diversity. Diversity extends to habitat,habits,nutrition,forms,etc.,of different organisms. Different varieties of flora and fauna are present all over the world. Living organisms have been classified variously according to different criteria, however, the two systems are most in use: 1. Two-kingdom system of classification 2.Five-kingdom system of classification. The kingdom Plantae is classified into divisions Algae, Bryophyta, Pteridophyta, Gymnospermae, and Angiospermae.

Pteridophyta

pteridophytes(Gr. pteron=feather,phyton=plant) constitute the most primitive seedless vascular plants that reproduce by means of spores and have neither fruits nor seeds. Hackel called these groups of plants pteridophytes because of their pinnate or feather-like fronds. It is also known as the “Botanical Snakes” or “Snakes of the plant kingdom”. sometimes they are also known as “amphibians of the plant kingdom” because they depend on water for fertilization just like bryophytes.

General Characters of Pteridophyta

1. They are found mainly in shady or damp places.
2. The plant body is made up of roots, stems, and leaves.
3. They have well developed vascular system(xylem and phloem) for the conduction of water and other substances, from one part of the plant body to another.
4. These plants have no flowers and do not produce seeds.
5. Multicellular sex organs are present.
6. A fertilized egg develops into an embryo.
7. water is essential for fertilization.
8. pteridophytes show a typical heteromorphic alternation of generations.
9. They show much variation in their form, size, and habit.
10. They range from small annuals to large tree-like perennials.

Affinities of Pteridophytes

Pteridophytes occupy an intermediate position between bryophytes and higher vascular plants(gymnosperms and angiosperms).

Resemblances of Ptreridophytes with Bryophytes

1. Both show heteromorphic alternation of generation.
2. The sexual reproduction in both groups is oogamous; the male and female reproductive structures are known as antheridia and archegonia.
3. water is essential for the opening of mature sex organs and fertilization in both groups.
4. certain pteridophytes are homosporous like bryophytes.

Differences between Bryophytes and Pteridophytes

1. The plant body of pteridophytes is differentiated into root, stem, and leaves, whereas in bryophytes it is thalloid or foliose.
2. Vegetative reproduction is more common in bryophytes than in pteridophytes.
3. Bryophytes are always homosporous, whereas many pteridophytes show heterospory.

Resemblances of Pteridophytes with Gymnosperms

1. The plant body in both groups is sporophytic, differentiated into root, stem, and leaves.
2. The vascular system is well developed in both groups, made up of xylem and phloem.
3. Like gymnosperms, many pteridophytes show heterosporous conditions.
4. Antherozoids of some gymnosperms are ciliated like those of pteridophytes.

Differences between Pteridophytes and Gymnosperms

1. pteridophytes usually occur in moist and shaded places, whereas gymnosperms grow in xerophytic habitats.
2. Gymnosperms have tap roots but in pteridophytes, the tap root is ephemeral and is soon replaced by adventitious roots.
3. The archegonium in pteridophytes has neck canal cells but they are absent in gymnosperms.

Uses of Pteridophytes

• Pteridophytes are economically very important as dry fronds of many ferns are used as cattle feed.
• Pteridophytes are also used in medicine.
• Pteridium aquilinum is the most widely used pteridophyte as a source of human food.

Conceptual Questions

Question 1: Write one important character of pteridophytes not found in gymnosperms.

Answer:

The presence of neck canal cells in archegonium in pteridophytes is an important characteristic of pteridophytes not found in gymnosperms.

Question 2: Name an aquatic fern.

Answer:

Salvinia , Marsilea are an aquatic fern.

Question 3: Which type of alternation of generation is seen in pteridophytes?

Answer:

Heteromorphic type alternation of generation is seen in pteridophytes.

Question 4: Give examples of pteridophytes.

Answer:

Azolla, Marsilea, Selaginella, Equisetum, etc are some of the examples of pteridophytes.

Question 5: Why pteridophytes are known as the “amphibians of the plant kingdom”?

Answer:

Because they depend on an external sources of water for fertilization just like bryophytes.

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