Haplo diplonitc life cycle (is also referred as diplohaplontic, diplo biontic of dibiontic ) show multicellular dipoid and haploid stages as dipicted in the following figure
Life Cycle of a Pteridophyte . The life cycle of a pteridophyte consist of two morphologically distinct phases
(i) The gametophytic phase
(ii) The sporophytic pyase
These two phases come one after another in the cycle of a pteridophyte. This phenomen is called alternation of generation . The gametophyte is haploid with single set of chrompsomes. It produces male sex organs antheridia and female sex organs archegonia.
(i) The antheridia may be embedded or projecting type. Each antheridium has single layered sterile jacket enclosing a mass of androcytes.
(ii) The androcytes are flask-shaped, sessile or shortly stalked and differentiated into globular venter and tubular neck.
(iii) The archegonium contains large egg. which is non-motile
(iv) The antherozids after liberation from anteridium, reaches up to the archeggonium fuses wiht the egg and forms a diploid structure known as zygotes.
(v) The diploid zygote is the fist cell of sporophytic generation. it is retained inside the archegonium and forms the embryo.
(vi) Teh embryo grows and develop to from sporophye which is differentiated into roots stem and leaves.
(vii) At maturiy the plant bears sporangaia, which encloses spore mother cells.
(viii) Each spore mother cells gives rise to four haploid spores which are susually arranged in tetrads.
(xi) The sporophytic generation and with the production of spores.
(x) Each spore is the first cell of gametophytic generation. it geminates to produce gametophye and completes its life cycle.
