In flowering plants, out of the two malegametes discharged in synergids, one fuseswith the egg and other fuses with thesecondary or definitive nucleus present incentral cell. Egg (n) + 1‌st male gamete (n) –––––▶ Zygote (2n)
Secondary‌nucleus
(2n)
(central‌cell‌nuclei)
+2‌nd male gamete (n) –––––▶PEN (3n)