LIFE CYCLE OF PTERIDOPHYTES
Pteridophytes are also known as Vascular amphibians/ Reptiles of the Plant Kingdom.
HABITAT:
• Limited to narrow geographical regions.
• Prefers cool, shady and damp places.
• Requires water for fertilization.
LIFE CYCLE:
Diplo-haplontic Life Cycle
BODY STRUCTURE:
SPOROPHYTE
• Main, photosynthetic, independent plant body.
• Well differentiated into true roots, stem and leaves.
• Vascular tissues i.e. Xylem and Phloem are present (First Tracheophytes)
• Stem- Modified into underground rhizomes.
• Roots- Adventitious roots arises from Rhizome.
• Leaves- Shows circinate vernation.
Small sized- Microphyllous Eg. Selaginella, Equisetum
Large sized- Macrophyllous Eg. Salvinia, Ferns
GAMETOPHYTE
• Multicellular, reduced, inconspicuous, heart shaped called Prothallus.
• Photosynthetic, thus independent plant body.
• Dorsiventrally flat.
• Homosporous species- Produce Monoecious gametophyte
• Heterosporous species- Produce Dioecious gametophyte
REPRODUCTION:
GAMETE FORMATION:
• The gametophyte bears Antheridium and Archegonium (male and female sex organs respectively) and is responsible for formation of Gametes.
• Male gametes- Antherozoids-
• • Biflagellated/ Multiflagellated
• • Spirally coiled
• Female gametes- Egg/ Oosphere- • Large, non-motile.
SPORE FORMATION:
• Leaves are modified to produce haploid spores by meiosis called Sporophylls
• Process of formation of spores- Sporogenesis
• Site of spore formation- Sporangium
• Cells responsible for spore formation- Spore Mother cells
• Mostly pteridophytes are homosporous i.e. produce only one type of spore.
• Few pteridophytes are heterosporous i.e. produce 2 different types of spores (microspore and megaspore)
Homosporous species- Pteris, Dryopteris, Lycopodium
Heterosporous species- Selaginella, Salvinia, Marselia