Understanding Ferns and Their Reproduction

Introduction

• Fern leaves (fronds) often have clusters on the underside resembling dirt.
• These clusters are important for fern reproduction.

Overview of Ferns

• Ferns are vascular plants:
  • Have true roots and vascular tissues.
  • Can grow tall (example: tree fern).
• Unique characteristic:
  • Do not produce flowers or seeds.

Reproductive Structures of Ferns

• Psori (plural), psoorus (singular):
  • Clusters on fern leaves help in reproduction.
  • Each psoorus contains sporangia.
  • Some ferns have inducial covering for protection.

Life Cycle of Ferns

Sporophyte Stage

• Lush green fronds represent the sporophyte stage:
  • Diploid cells with two sets of chromosomes.
  • Produce haploid spores via meiosis.
• Sporangia release spores through the process involving an annulus:
  • Water evaporation causes the annulus to cavitate, ejecting spores.

Germination and Prothallus Stage

• Spores germinate on moist surfaces and undergo mitosis:
  • Form a prothallus (haploid gametophyte).
  • Prothallus is anchored by rhizoids.
  • Often unnoticed due to small size (few millimeters).

Gametophyte Stage

• Prothallus produces both male and female gametes:
  • Enteridia (male; produces sperm) and Archegonia (female; produces eggs).
  • Strategies prevent self-fertilization (e.g., pheromones).
• Sperm movement:
  • Flagellated and dependent on water.

Fertilization and Development

• Fertilization forms a zygote, leading to the development of an embryo:
  • The embryo grows into a new sporophyte, attached to the gametophyte.
  • Gametophyte dies off after supporting the young sporophyte.

Asexual Reproduction in Ferns

• While sexual reproduction is common, ferns can reproduce asexually:
  • Bulbils in hen and chicken's fern (vegetative reproduction).
  • Rhizomes lead to cloning, creating large colonies.

Conclusion

• Ferns have unique reproductive strategies and life cycles.
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