The diploid multicellular stage of a plant or alga's life cycle is known as a sporophyte.
Each sporophyte cell contains a double pair of chromosomes, one set from each parent, as it develops from the zygote created when a haploid egg cell is fertilized by a haploid sperm.
A multicellular diploid sporophyte phase and a multicellular haploid gametophyte phase alternate in all terrestrial plants and the majority of multicellular algae's life cycles.
Gametophyte, gamete and spore are alwayshaploid(n) and only contain one set of chromosome from either of the parent.
