Answer: It is called Alternation of generation.
Step-by-step explanation:
Alternation of generation or metagenesis is a type of reproductive life cycle that occur in plants and algae that have distinct haploid sexual and diploid asexual reproduction stages. The diploid sporophyte undergoes meiosis to produce haploid reproductive cells called spores.The spores then develop into haploid male and female gametes(which is the gametophyte generation) fuse together to produce diploid zygotic sporophyte. This occur in some vascular plants, fungi, and protists.