Haplo diplontic life cycle (is also referred as diplohaplontic, diplo biontic or dibiontic) shows multicellular diploid and haploid stages as dipicted in the following figure.
Life Cycle of a Pteridophyte The /ife cycle of a pteridophyte consists of two morphologically distinct phases
(i) The gametophytic phase
(ii) The spoiophytic phase
These two phases come one after another in the life cycle of a pteridophyte. This phenomenon is called alternation of generation. The gametophyte is haploid with single set of chromosomes. 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 antherozoids after liberation from antheridium, reaches up to the archegonium fuses with the egg and forms a diploid structure known as zygotes.
(v) The diploid zygote is the first cell of sporophytic generation. It is retained inside the archegonium and forms the embryo.
(vi) The embryo grows and develop to form sporophyte which is differentiated into roots, stem and leaves.
(vii) At maturity the plant bears sporangia, which encloses spore mother cells.
(viii) Each spore mother cell gives rise to four haploid spores which are usually arranged in tetrads.
(ix) The sporophytic generation ends with the production of spores.
(x) Each spore is the first cell of gametophytic generation. It germinates to produce gametophyte and completes its life cycle.
