In angiosperms, gametophytic cells fuse to form the triploid (3n) endosperm and the diploid (2n) zygote.

In gymnosperms, a diploid zygote is also formed but rather than forming a triploid endosperm, this group of plants stores food as the haploid (1n) female gametophyte.

Photo of the cross section of a seed with the endosperm and embryo identified.