Plants have both sporophytic and gametophytic generation which alternate with each other to complete the life cycle . Alteration with spore producing diploid sporophyte with haploid gametophyte is known as alteration of generation and it takes place in most of the plants.
HAPLONTIC LIFE CYCLE:
HAPLONTIC LIFE CYCLE: In this the main plant body is haploid gametophyte which is dominant phase in life of plant .This gametophyte produces gametes which fuse to form diploid zygote ( sporophyte) which produces spores by meiosis these haploid spore now form main plant body gametophyte. Ex. Spirogyra,Ulothrix etc.
DIPLONTIC LIFE CYCLE
Main plant body is diploid sporophyte which is long lived it produces gametes by gametogenesis these are haploid and short lived they fuse to form zygote which by division form main plant body sporophyte . Ex.Gymnosperm and Angiosperm.
DIPLOHAPLONTIC LIFE CYCLE
In this type both the gametophytic and sporophytic generations are of equal duration and both are independent structures. Gametophytic plant body is concerned with gamete formation which by syngamy produces sporophyte which produces spores to form gametophyte.such a life cycle in which there is alteration of independent two plant bodies gametophyte and sporophyte that is known as diplohaplontic life cycle. Ex. In some Bryophytes and pteridophytes.
