Endosperm is the nutritive tissue that surrounds the embryo. The phenotype of the endosperm depends upon the dominant allele present.
In corn, one nucleus from one male gametophyte fuses with two nuclei from the female gametophyte giving rise to a triploid cell (3n), which replicates and form the endosperm.
In the cross, f'/f'(female) x f"/f"(male)
Polar nuclei is f' and f'
Sperm is f" and f"
| Female | Male | Polar nuclei | Sperm | Endosperm (3n) |
| f'/f' | f'/f' | f' and f' | f"/f" | f'/f'/f"(floury endosperm) |
| f"/f" | f'/f' | f" and f" | f'/f" | f"/f"/f'(flinty endosperm) |
This can be explained as follows: -
Endosperm is developed by the fusion of one sperm with two polar nuclei giving rise to f'f'f" that is floury endosperm because the dominant allele is f', which is floury.
In the reciprocal cross, the female is f"/f" and the male is f'/f'.
So, the cross is between the f"/f" polar nuclei and f'/f' sperm. This results in triploid cell (f"/f"/f'), which forms flinty endosperm.