What is the difference between endosperm and perisperm?
They are both nutritive layers in a seed. Perisperm develops from the nucellus of the seed and the endosperm develops when the sperm cell fuses with two haploid polar nuclei (contained in the central cell) in the centre of the embryo sac (or ovule). The resulting cell is triploid (3n). This triploid cell divides through mitosis and forms the endosperm, a nutrient-rich tissue, inside the seed.