Characteristics, importance, types (ferns)

1. Introduction

1. Pteridophytes are the first true land plants to develop vascular tissues (xylem and phloem).
2. They are often called the "Botanical Amphibians" as they require water for fertilization.
3. Commonly found in moist and shady places like forests, hillsides, and riverbanks.
4. Examples include ferns, horsetails, and club mosses.
5. The dominant phase in their life cycle is the sporophyte.

2. Characteristics of Pteridophytes

1. Possess well-developed vascular tissues (xylem and phloem).
2. Have true roots, stems, and leaves.
3. Leaves are called fronds, and young leaves show circinate vernation (coiled structure).
4. Reproduce through spores, not seeds.
5. Exhibit alternation of generations with dominant diploid sporophyte and small haploid gametophyte.
6. Require water for fertilization, as motile sperm swim to the egg.

3. Classification of Pteridophytes

1. Pteridophytes are classified into four major groups:

3.1 Psilopsida (Whisk Ferns)

1. Most primitive pteridophytes.
2. No true leaves and roots; photosynthesis occurs in the stem.
3. Example: Psilotum.

3.2 Lycopsida (Club Mosses)

1. Small plants with microphyllous leaves (small leaves).
2. Reproduce using spores in cone-like structures called strobili.
3. Examples: Lycopodium, Selaginella.

3.3 Sphenopsida (Horsetails)

1. Have jointed, hollow stems and scaly leaves.
2. Stems contain silica, making them rough.
3. Example: Equisetum.

3.4 Pteropsida (Ferns)

1. Most advanced and largest group of pteridophytes.
2. Possess large leaves called fronds.
3. Sporangia are present on the underside of fronds in clusters called sori.
4. Examples: Pteris, Dryopteris, Adiantum.

4. Life Cycle of Pteridophytes

1. Exhibit alternation of generations with dominant sporophyte stage.

4.1 Sporophyte Stage

1. Diploid and dominant stage.
2. Produces spores inside structures called sporangia.
3. Sporangia are grouped into clusters called sori, present on the underside of fronds.

4.2 Gametophyte Stage

1. Haploid and small, called a prothallus.
2. Grows in moist environments and is independent of the sporophyte.
3. Produces antheridia (male) and archegonia (female) organs.
4. Water is required for fertilization.

5. Economic and Ecological Importance of Pteridophytes

5.1 Ecological Importance

1. Help in soil conservation by preventing erosion.
2. Act as pioneer species in barren and rocky areas.
3. Some ferns are used for nitrogen fixation in symbiotic relationships.

5.2 Economic Importance

1. Ferns are used as ornamental plants for decoration.
2. Horsetails (Equisetum) are used as abrasives due to silica content.
3. Some pteridophytes have medicinal properties and are used in herbal medicine.
4. Fossilized pteridophytes contribute to the formation of coal deposits.

6. Comparison of Pteridophytes and Bryophytes

7. Conclusion

1. Pteridophytes are the first plants with vascular tissues.
2. They have a dominant sporophyte stage and reproduce via spores.
3. Important in ecology, medicine, and coal formation.