LIFE CYCLE OF PTERIDOPHYTES

Pteridophytes are also known as Vascular amphibians/ Reptiles of the Plant Kingdom.

• Limited to narrow geographical regions.

• Prefers cool, shady and damp places.

• Requires water for fertilization.

Diplo-haplontic Life Cycle

• 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

• Multicellular, reduced, inconspicuous, heart shaped called Prothallus.

• Photosynthetic, thus independent plant body.

• Dorsiventrally flat.

• Homosporous species- Produce Monoecious gametophyte

• Heterosporous species- Produce Dioecious gametophyte

• 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.

• 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